techno-economic analysis of wireless indoor solutions
TRANSCRIPT
Techno-Economic Analysis of WirelessIndoor Solutions
ZEESHAN ZUBAIR
Master of Science ThesisStockholm, Sweden 2011TRITA-ICT-EX-2011:16
Techno-Economic Analysis of WirelessIndoor Solutions
ZEESHAN ZUBAIR
Master of Science Thesis performed at
the Radio Communication Systems Group, KTH.
January 2011
Examiner: Ben Slimane
KTH School of Information and Communications Technology (ICT)Department of Communication Systems (CoS)
TRITA-ICT-EX-2011:16
c⃝ ZEESHAN ZUBAIR, January 2011
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Abstract
Introduction of mobile broadband technology added valuable service for mobile users
to surf faster internet on mobile. This impacts the traffic demand requirements, traffic
demand increased for network to fulfill the requirements. Higher data rates depend
on strong signal from base station and capacity of the network. Mostly people are
located inside the building for surfing internet. Traditional macro base stations are not
sufficient to deal with data users for indoor users because presence of strong
attenuations inside the building resists signal from macro base stations. As a
consequence wireless indoor solutions are introduce to provides coverage and
capacity requirements inside building. Femtocell, Picocell, WLAN and Distributed
Antenna Systems (DAS) are common indoor solutions to provide coverage and
capacity requirements.
In this thesis techno-economic and analysis was carried out to explore the
performance, cost of indoor solutions. The aim is to estimate the cost economical
wireless indoor solution and to identify which indoor solution is suited in which
scenario which helps in radio indoor planning and selection of indoor solution. For the
capacity requirements four radio access technologies UMTS, HSDPA, LTE and
802.11 with different spectral efficiency levels are considered as an input for indoor
solutions. Single wireless indoor network is enough to deploy in a building to provide
coverage and capacity requirements. Users from different market actors are located
inside the building. It is not efficient way to deploy multiple indoor networks in a single
building.
Analysis revealed that the Femtocell is cost-economical and flexible solution that
capable of handle variations in traffic demand and stable system, it is proposed as a
long term wireless solutions. Moreover from analysis Femtocells cost distribution is
almost same in all radio access technologies this makes it perfect solution for all
systems. Picocell and DAS solutions are mostly affected by the traffic demands and
spectral efficiency. Increase in spectral efficiency tends to decrease the network cost
of Picocell and DAS. From analysis WLAN found stable system capable of providing
uniform cost distribution for low and high level demands scenarios and different level
of spectral efficiency.
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Acknowledgment
The completion of master thesis has been rewarding experience for me. The thesis carried out at Wireless@KTH, this department is renowned for innovative and excellent research center for Sweden. For this thesis, I would like to express my gratitude to my parents for extraordinary support and co-operation and my supervisor Jan Markendahl who helped me during entire thesis with his valuable time, motivation and knowledge, without his cooperation this thesis seems to be impossible. Furthermore, I would like to thanks to Mats Nilson for additional help on several events and Ben Slimane for examining my thesis. I cannot forget KTH and Sweden for providing a opportunity for study in highly competitive master program „Wireless Systems‟ which made strong base of research in wireless area. The journey of Sweden was so amazing and full of adventurous, several ideas and things learned during my studies especially cooking and time management. Finally, thanks for Wireless@KTH department for providing extra-ordinary facilities and ideal environment for research. The management and people of Wireless@KTH supported and helped me in every event.
Zeeshan Zubair
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Contents
List of Diagrams ....................................................................................................................... vii
List of Tables ............................................................................................................................. ix
List of Acronyms ....................................................................................................................... xi
Chapter 1 .................................................................................................................................... 1
1 Introduction ........................................................................................................................ 1
1.1 Background .................................................................................................................. 1
1.2 Problem Definition ...................................................................................................... 2
1.3 Related Work ............................................................................................................... 2
1.4 Report Outline ............................................................................................................. 3
Chapter 2 .................................................................................................................................... 5
2 Introduction of Wireless Indoor Solutions ......................................................................... 5
2.1 In-building Solutions: .................................................................................................. 5
2.2 Femtocell ..................................................................................................................... 5
2.3 Picocell ........................................................................................................................ 6
2.4 WLAN ......................................................................................................................... 7
2.5 Distributed Antenna System (DAS) ............................................................................ 8
2.5.1 Passive DAS ......................................................................................................... 9
2.5.2 Active DAS ........................................................................................................ 11
Chapter 3 .................................................................................................................................. 13
3 Wireless Data Access Standards ...................................................................................... 13
3.1 Introduction of 3G Networks ..................................................................................... 13
3.1.1 Universal Telecommunication System (UMTS) ................................................ 13
3.1.2 High-speed Downlink Packet Access (HSDPA) ................................................ 15
3.1.3 Long Term Evaluation (LTE) ............................................................................ 16
3.2 IEEE 802.11 Standards .............................................................................................. 17
Chapter 4 .................................................................................................................................. 19
4 Techno-Economics of Wireless Indoor Solutions ............................................................ 19
4.1 Techno-Economic Model .......................................................................................... 19
4.2 General Models .......................................................................................................... 20
4.2.1 Link Budget ........................................................................................................ 21
4.2.2 Propagation Models ............................................................................................ 23
4.2.3 Cell Radius Estimation ....................................................................................... 24
4.2.4 Area Coverage .................................................................................................... 25
4.2.5 Placement of base stations .................................................................................. 25
4.2.6 Capacity (Number of Base Stations) .................................................................. 26
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4.3 Network Designing .................................................................................................... 26
4.3.1 Femtocell, Picocell and WLAN Case................................................................. 27
4.3.2 Active DAS Case ............................................................................................... 28
4.4 Cost Models ............................................................................................................... 31
4.4.1 Infrastructure Cost .............................................................................................. 31
4.4.2 Femtocell, Picocell and WLAN case ................................................................. 33
4.4.3 Active DAS case ................................................................................................ 34
4.4.4 Net Present Value (NPV) ................................................................................... 35
Chapter 5 .................................................................................................................................. 37
5 Case Study Assumptions .................................................................................................. 37
5.1 Scenario ..................................................................................................................... 37
5.2 Traffic Demand .......................................................................................................... 38
5.3 Spectral Efficiency .................................................................................................... 38
5.4 DAS Type .................................................................................................................. 39
5.5 Power per Carrier (active DAS) ................................................................................ 39
Chapter 6 .................................................................................................................................. 41
6 Network Dimensioning Results ....................................................................................... 41
6.1 Coverage .................................................................................................................... 41
6.2 Capacity ..................................................................................................................... 41
6.3 Femtocell, Picocell and WLAN Network .................................................................. 42
6.4 Active DAS Network ................................................................................................. 42
Chapter 7 .................................................................................................................................. 47
7 Cost Results ...................................................................................................................... 47
Chapter 8 .................................................................................................................................. 51
8 Conclusion and Future Work ........................................................................................... 51
8.1 Conclusion ................................................................................................................. 51
8.2 Future Work ............................................................................................................... 53
Bibliography ............................................................................................................................. 55
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List of Diagrams
Diagram 2.1 Femtocell Architecture .......................................................................................... 6
Diagram 2.2 Picocell Architecture ............................................................................................. 7 Diagram 2.3 WLAN Architecture .............................................................................................. 8 Diagram 2.4 Coverage from Distributed Antenna System ........................................................ 9 Diagram 2.5 Passive Distributed Antenna System ................................................................... 10 Diagram 2.6 Active Distributed Antenna System ................................................................... 12
Diagram 3.1 UMTS uplinks and downlink frequencies band .................................................. 14 Diagram 4.1 Techno-economic Model .................................................................................... 19 Diagram 4.2 Link Budget Components .................................................................................... 21
Diagram 4.3 PLS values for different environment [20] ......................................................... 24 Diagram 4.4 Cell Radius for specific environment type .......................................................... 25 Diagram 4.5 Place of antenna with certain coverage overlap for full coverage ..................... 26 Diagram 4.6 Number of base stations for satisfying coverage and capacity requirements ..... 27
Diagram 4.7 Flow chart for calculating active DAS elements ................................................. 29 Diagram 4.8 Cost Model for Femtocell, Picocell and WLAN ................................................. 33 Diagram 4.9 Cost Model for active DAS ................................................................................. 34 Diagram 5.1 Skatteverket’s Building Architecture (Top View) .............................................. 37
Diagram 6.1 Active DAS network for low level demand ........................................................ 44 Diagram 6.2 Active DAS for high level demand ..................................................................... 45
Diagram 7.1 NPV for active DAS for low and high level demand .......................................... 48 Diagram 7.2 NPV for Picocell for low and high level demand ............................................... 49
Diagram 7.3 NPV for Femtocell for low and high level demands ........................................... 49 Diagram 7.4 NPV for WLAN for low and high level demands ............................................... 49 Diagram 7.5 NPV for DAS, Picocell and Femtocell for all low level demand........................ 50
Diagram 7.6 NPV for DAS, Picocell and Femtocell for high level demand ........................... 50
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List of Tables
Table 3.1 802.11 standards ....................................................................................................... 17
Table 4.1 Link budget for downlink ......................................................................................... 22 Table 4.2 Link budget for uplink ............................................................................................. 23 Table 5.1 Average throughput with different amount of spectrums and spectral efficiencies . 39 Table 5.2 Power per Carrier for DAS ...................................................................................... 39 Table 6.1 Number of base stations/antenna elements for different type of floors ................... 41
Table 6.2 Number of base station for different values of spectral efficiencies ........................ 42 Table 6.3 Number of base station for different values of spectral efficiencies ........................ 42 Table 6.4 Active DAS elements for low and high level demand ............................................ 43
Table 6.5 Length of cables for low and high level demand ..................................................... 43 Table 7.1 CAPEX, OPEX and NPV for Femtocell .................................................................. 47 Table 7.2 CAPEX, OPEX and NPV for Picocell ..................................................................... 47 Table 7.3 CAPEX,OPEX and NPV for Active DAS ............................................................... 48
Table 7.4 CAPEX, OPEX and NPV for WLAN ...................................................................... 48
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List of Acronyms
GSM Global System for Mobile Communication GPRS General Packet Radio Service EDGE Enhanced Data Rates for Global Evolution EV-DO Evaluation Data Optimized EV-DO Rev. A Evaluation Data Optimized Rev. A EV-DO Rev. B Evaluation Data Optimized Rev. B HS-DSCH High Speed- Downlink Shared Channel ISM Industrial, Scientific and Medical LTE Long Term Evaluation OFDM Orthogonal frequency-division Multiplexing RF Radio Frequency Trans. Transmission UMB Ultra Mobile Broadband UMTS Universal Mobile Telecommunication System E-UTRA Evolved Universal Terrestrial Radio Access UTRA Universal Terrestrial Radio Access WCDMA Wideband Code Division Multiple Access WCDMA-FDD Wideband Code Division Multiple Access-
Frequency Division Duplex WCDMA-TDD Wideband Code Division Multiple Access-Time
Division Duplex 1×RTT One Time Radio Transmission Technology 3G Third Generation 3GPP Third Generation Partnership Project 3GPP2 Third Generation Partnership Project 2
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Chapter 1
1 Introduction
1.1 Background
Introduction of mobile broadband is beneficial for subscriber through which Internet can be used in mobile every place where the services of operators are available. Mobile broadband requires more bandwidth as compare to voice services and this is problematic for operators with respect to revenue while providing flat rate subscription. Introduction of 3G services beneficial for users for providing mobile broadband services, on the other hand there are some issues with the deployment of 3G systems that cannot be omitted. The performance of 3G with respect to coverage especially inside building or indoor areas and capacity is not reliable when comparing with old 2G technology. Mobile broadband users mostly active in buildings, offices, centrums and homes because of cold weather situations and during surfing of internet on mobile they are stationary. It implies the indoor users can not be neglected and majority of mobile broadband users are indoor users.
Dedicated in-building coverage helps offload the macro network. In-building solutions offload the macro base station by reducing average downlink power levels and indoor solutions are isolated from the macro cells as a result low interference occurs. Better capacity and coverage requirement can be fulfilled by using indoor solutions such as Distributed Antenna Systems, Femtocells, picocells and WLAN. These indoor solutions are low coverage and high data rates solutions [6]. Another impact of arrival of mobile broadband is the increasing of data traffic. The high mobile traffic requires more capacity from the network to handle the mobile broadband users. This can be achieved by using more amount of spectrum, number of base stations or access points, spectral efficiency and the type of indoor solution. The increasing in demand directly impacts the cost structure of indoor solutions. The more demand require more resources and which increases the cost for the network. Different type of indoor solution has non-similar cost distribution some have constant cost distribution and some are linearly increasing with the demand. The theme is to analyze which indoor solution is suitable and cost economical to fulfills the demand requirement so that suitable indoor solution is to be used and wasting of resources minimized. Moreover the benefit of installation of indoor solutions is that it can be share by multiple operators. It is very difficult for the operator to deploy indoor base station to each building where coverage is the problem as well as it is not efficient way that
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each operator deploy its own separate indoor system in a single building. The sharing of resources is beneficial for the operator with respect to installation of indoor system and revenue. For sharing of resources there is model required for the sharing of installation of indoor system and revenue.
1.2 Problem Definition
The importance of Indoor users can not be avoided with the introduction of mobile broadband. As a consequence which solution is suitable for providing indoor solution with respect to cost optimal and technical point of view? The aim of this thesis project is to compare both technical performance like cost and capacity of the wireless indoor access and the transmission as well as the different options for cooperation. The following questions need to be addresses:
Will Femtocell be cost economical and stable system than WLAN (no modification required every year)?
Will the cost distribution of Femtocell and WLAN be same if variation occurs in traffic demand?
Which indoor solution‟s cost distribution varies when different RATs are used?
Will increment in traffic demand affects DAS and Picocell‟s cost distribution?
1.3 Related Work
Indoor techniques Distributed Antenna System, Femtocells, Picocells and WLAN are widely discussed in past. Many business and white papers representing comparison of different RATs with respect to complete cost analysis. Femtocells are studied in [1] and [13], which provides cost analysis and several business models for market actor for sharing resources. The major emphasis of this study is on Femtocells In which the Femtocells are compared with macro cells with respect to cost, capacity and coverage in deployment scenarios cases. Secondly a two dimensioned business model in [1] is discussed between operator of the indoor network and different kind of users that can access the network. Studies [9], [14] and [15] cover WLAN cost analysis. In [9] WLAN and Picocell is compared with macro and micro base station. The 3G system Evolution-Data Optimized (EV-DO) is compared with WLAN in [14]. Femtocell and WLAN which are indoor solution providing higher data rates are discussed in [15]. Picocells are covered in [16] and [17]. Picocell compared with Macro cell in [16] and in [17] Picocell compared with Macro and Micro cell.
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After all it is concluded many studies cover some part of this thesis with respect to cost analysis. In mostly studies indoor solutions compared with Macro base station and some studies compares indoor solutions as well.
1.4 Report Outline
Chapter 2: This chapter covers the brief information about wireless indoor solutions; Femtocell, Picocell, WLAN, Distributed Antenna Systems (active and passive). The information about indoor solutions based on operation, properties, differences and architecture of network.
Chapter 3: Wireless radio access standards are described in this chapter. UMTS, HSDPA, LTE and 802.11 standards with their data rates, spectral efficiency are represented. Chapter 4: In this chapter techno-economics of Wireless indoor solutions are covered. Models and methods for estimation of coverage, capacity, network designing and cost are explained. Chapter 5: This chapter covers the case study assumptions for this thesis. In this thesis scenario, spectral efficiency and traffic demand are the main assumptions made. Chapter 6: The results for network dimension are shown in this chapter. The results are described according to coverage and capacity wise. Moreover this chapter also includes required network elements for fulfilling coverage and capacity. Chapter 7: In this chapter cost results which are estimated from cost models are represented. CAPEX, OPEX and NPV for each indoor solution with different level of demand and spectral efficiency are shown. Chapter 8: Conclusion and future work discussed in this chapter.
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Chapter 2
2 Introduction of Wireless Indoor Solutions
2.1 In-building Solutions:
Introduction of mobile broadband services provided faster internet on mobile but on the other hand it initialize the importance of in-building solutions which was not severely important for 2G systems. More than 70% mobile broadband users present in building, schools, cafes, offices etc. Higher data rates inside buildings requires strong signal strength inside building which introduces the requirements of coverage and capacity inside building and thus the importance of indoor coverage is mandatory. There are many ways to provide indoor coverage, most common way is to use traditional Macro cell concept. When deploying macro cell concept for covering buildings problems many problems may occurs. The macro base station are mounted on the roof of building, losses present in building like wall, glass and wood attenuations degrades signal from macro base station. Moreover the problem introduces for those buildings which are far from macro base station, distance between mobile and base station are high which degrades the quality of signal and services as well.
The above problems can be minimized by using dedicated in-building solutions as compare to Macro cell concept. Mostly deployed in-building solutions are Femtocell, Picocell, Distributed Antenna System (DAS) and WLAN. The detail of each in-building solution is given below.
2.2 Femtocell
Femtocells are low price in-building solutions that provide coverage in home or offices. Femtocells are smaller than picocells. Femtocells are low power output, capacity and gain. Femtocells are „self-configuring‟ i.e. they can sense environment and adjust the capabilities according to the environment. The architecture of Femtocell is shown in Diagram 2.1. For Femtocell a Gateway Controller like a Radio Network Controller (for macro base station) is installed by the operator in Mobile Core Network side. Mobile Core Network is connected to the Femtocell Gateway Controller. Femtocell is connected to Mobile core network via residential DSL or cable broadband internet through broadband router and operates in licensed band.
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Femtocells are capable of providing higher capacity equivalent to 3G network with low transmission power than improves the battery life of mobile users without requirement of additional mobile feature requirements like Wi-Fi. Femtocells uses users existing resources for backhaul problems that occurs in macro base station case. The deployment of Femtocells enables enormous opportunities for operators or market actors for sharing resources and providing in-building coverage that also beneficial for mobile users. The radio planning for femtocells is similar to Picocell, just radiating from lower power.
2.3 Picocell
Picocells are small base stations capable of providing coverage on hot-spots or in-building as compare to macro cells. Picocells are low coverage and capacity that designed for provide in-building coverage. Picocells adds capacity to network with low cell distortion and interference problems, compatible with existing system, operates in licensed frequency bands, solving handover problems and easy installation. The architecture of Picocell is shown in Diagram 2.2. The Picocell is based on three components the Picocell base station, controller and manager. Picocell base station communicates with the mobile handset with no special handset requirements like Wi-Fi. Picocell is connected to base station controller via IP network for the backhaul. Picocell base station controller connects picocells with mobile core network and routes all the IP traffic between Picocell and mobile core network. The Picocell manager also called OMC-R (Operations and Maintenance Center. Radio) which is connected to controller responsible for provides all facilities required for the operation and maintenance of the picocells and the controller.
Mobile Core
Network
Femtocell
Gateway
Controller
Internet
Broadband
Router
Femtocell
Diagram 2.1 Femtocell Architecture
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Low price Picocell base station reduces CAPEX with simple IP backhauls which reduces OPEX as well. Picocells are simple, robust and easy configurable system which provides many options for operator for sharing and business modeling. Picocell base station is capable of providing indoor coverage up to 200 m depending upon the environment and wall attenuation. Picocells are deployed using a single Ethernet connection that‟s fulfils the power, traffic and control signaling requirements. Picocell also provides Network Listen property that enables RF planning provides radio indoor planners to see into the environment and set coverage and reduces the interference.
2.4 WLAN
Wireless Local Area Networking (WLAN) are low coverage and limited capacity access points capable for providing higher data rates compare to any cellular technology. WLAN are operated in 2.5 and 5 GHz. The architecture of WLAN is shown is Diagram 2.3. WLANs are based on components which are Authentication Server, Access Controller and Access Point. Authentication Server is responsible for authentication of users and accesses the billing record of users. Access Controller which is located at end point of IP packet network allocates the IP address to users. Mobile users communicate with WLAN‟s Access Point to share information.
Mobile
Core
Network
Picocell Base
station Controller IP
Network
Picocell
Manager
Picocell
Diagram 2.2 Picocell Architecture
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WLANs are distributed capacity network that distributes the capacity in a building by the use of distributed base stations or WLAN access points. WLAN have limited frequencies and similar principle as in cellular network applies to deploy WLAN access points that fulfill the coverage and capacity requirements. WLANs are designed for Hot-spot Coverage that covers hot-spot areas in the building. It is possible to deploy three or four WLAN carriers in same area or floor in a building to maintain the minimum quality of service and maintain interference requirements. Rapidly growing WLAN penetration for covering in-building scenarios provides good business and sharing opportunities. High capacity WLANs overcomes the high demand problems which come from the arrival of mobile broadband technology. WLANs are provides long term solution for demand increasing scenarios in which the traffic demand increases every year. Terminals or mobile users communicate with WLAN Access Point with WLAN enabled adaptors.
2.5 Distributed Antenna System (DAS)
A Distributed Antenna System is another solution to provide indoor coverage. The basic principle of DAS is to divide the coverage area into smaller coverage regions and each DAS covers the smaller region. The division of coverage area into smaller regions improves the performance in terms of path loss and transmission power. The path loss decreases with the use of multiple antennas and hence less power from the base station required from the base station to cover the area as a consequence less power from the mobile needed to communicate with the DAS antenna which improves the battery life of mobile. In DAS several antenna elements are connected to base station through co-axial cable or fiber optic. The architecture of DAS is shown in Diagram 2.4. The DAS is mainly categorized into two types called passive and active DAS.
Mobile Core
Network
Authentication
Server
IP Core Access
Controller
C
WLAN
Access Point
Diagram 2.3 WLAN Architecture
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Passive DAS system requires more power from the base station that fulfils the requirement for coaxial cables and splitters present in the building. The designing of passive systems are simple but due to rigidness of co-axial cable it may take time to install. The problem occurs with the passive solutions is that they are not capable of providing uniform coverage in building due to cable losses in passive system. The cable losses producing the higher noise level which generates problem to mobile users especially in uplink. Active DAS system consists of active RF components which are interconnected with fiber optic and co-axial cables. The use of fiber optic cable minimizes the cable losses and provides uniform coverage in the building and less power required from the base station to provide coverage in area.
2.5.1 Passive DAS
In Passive DAS the antenna elements are connected to macro or micro base station with coaxial cable as shown in Diagram 2.5. Co-axial comes with different thickness according to the requirement and load. In diagram 2.5 the vertical co-axial cable that connects base station with multiple floors is thicker than the horizontal co-axial cable. The tappers on each floor tap off the power to horizontal co-axial cable to splitters and splitter fed power to several antennas which are connected to splitters. Moreover passive DAS supports multi band operations and filters are used to separate different frequency bands.
BS
B
S
DAS Antenna
Power Splitter
Base Station
Diagram 2.4 Coverage from Distributed Antenna System
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Floor 2
Floor 1
BS
A A
A A
A Antenna
Tappers
Splitter
Diagram 2.5 Passive Distributed Antenna System
2.5.1.1 Passive DAS Advantages
1) Passive DAS are simple to deploy but rigidness of co-axial cable make it time-
consuming.
2) Passive DAS is more suitable for harsh environments for this reason they are
good to deploy in industrial plants and garages etc.
3) Components from different manufacturers are easily compatible with each
other.
2.5.1.2 Passive DAS Disadvantages
1) Presence of co-axial cable produces more losses in the system.
2) At higher frequencies the co-axial cable has more attenuation which degrades
the service of the system.
3) Due to high losses from the co-axial cable more power require from the base
station for coverage.
4) Link budget for balancing all antennas and uniform coverage is difficult.
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2.5.2 Active DAS
Active DAS uses active components with fiber optic and co-axial cable that minimizes the cables losses which normally occurs in passive DAS. Active DAS consists of main unit, expansion unit and remote unit. The architecture of Active DAS is shown in Diagram 2.6.
2.5.2.1 Main Unit
The main is the central part of the network. Main unit provides connectivity between base station and expansion unit via fiber optic cable. Main unit is responsible for monitoring the performance of DAS system. Main unit generates alarming signal to the base station if some problems occurs in the systems so that root of the problem can be identified and resolved quickly. The status of the whole system is possible to see on the main unit using LEDs, an LCD display or with the help of connected PC depends on the manufacturer of the system which facilities are they providing.
2.5.2.2 Expansion Unit
Expansion unit responsible for converting optical signal arrives from the main unit to electrical signals that further use by remote unit. Maximum 4 expansion units can be connected to the main unit and typical the distance between main unit and expansion unit is 1.5 km with multi mode fiber and 6 km for single mode fiber.
2.5.2.3 Remote Unit
Remote units are connected to expansion units through thin IT cables or CAT 5, maximum 8 remote units can be connected to single expansion unit. The expansion unit delivers DC power to remote unit so there is not any external power required for remote unit. Antenna is connected to remote unit and remote unit converts the electric signal from the expansion unit to downlink radio signal for mobiles and uplink radio signal from the mobile to electric signal for expansion unit. The uplink losses are minimized by connecting antennas near the remote unit.
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2.5.2.4 Active DAS Advantages
1) The RF losses in active DAS are far lower than passive DAS due to use of active components and fiber optic cable.
2) The use of fiber optic cable in active DAS provides uniform coverage which
was not achieved by passive DAS.
3) The minimization of cable losses makes active DAS suitable for medium to large size buildings like hospitals, shopping malls, head offices etc.
4) Low power required from the base station to active DAS, hence it removes the
requirements of heavy supply, air conditioning for cooling etc.
Co-axial Cable Upto 400 m
Cat 5 Cable Optical Fiber
Up to 6 Km
Base
Station
Main
Unit
Expansion
Unit
Expansion
Unit
Remote Unit
Remote Unit
Remote Unit
Remote Unit
Remote Unit
Remote Unit
Remote Unit
Remote Unit
A
A
A
A
A
A
A
A
Diagram 2.6 Active Distributed Antenna System
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Chapter 3
3 Wireless Data Access Standards
In this chapter various standards for wireless data access are covered. The idea is to get some basic knowledge about the wireless data access standards and to identify the differences among them. The overview of 3G and 802.11standards are discussed with some important things and not covered in more detailed way.
3.1 Introduction of 3G Networks
3G networks is the third generation of mobile networking and communication. 3G networks are capable of providing voice services, text services, data services, internet, mobile TV and video streaming are emerging so faster in the market due to users friendly applications with reliable communication. Before that the mobile network provided services like voice, text and low speed data services. 3G networks provide higher data rates or spectral efficiency as compare to 2G networks in uplink and downlink. Third generation network are based on packet switching concept as compare to circuit switching which is used in second generation mobile networks. 3G network is categorized into two group families Third generation Partnership project (3GPP) and Third generation Partnership project 2 (3GPP2) according to the standards. 3GPP covers Global System for Mobile Communication (GSM) including GPRS and EDGE, UMTS and LTE (including LTE-Advanced). 3GPP2 was established to help North American and Asian operators based on CDMA2000 switching to 3G. 3GPP2 covers One Times Radio Transmission Technology, EV-DO, EV-DO Rev. A, EV-DO Rev. B and UMB. In this thesis we deal with the UMTS, HSDPA, LTE and WLAN standards which are explained below.
3.1.1 Universal Telecommunication System (UMTS)
UMTS it the evolution of GSM sometimes called 3GSM from its GSM foundation. Several good points about UMTS that‟s includes UMTS in 3G category. UMTS is very efficient in utilizing the radio resources or spectrum. UMTS capable of rejection of narrowband interference and provides strong robustness against frequency-selective fading. UMTS radio interface is totally different as compare to GSM. UMTS uses two types of WCDMA interface i.e. WCDMA-TDD and WCDMA-FDD. In WCDMA-TDD uses the same frequency for uplink and downlink transmission with different time slots. Some guard interval between transmission and reception to overcome the problem of interference. For the case of WCDMA-FDD it required separate frequencies for uplink and downlink i.e. a paired set of bands needed, one for uplink and one for downlink. WCDMA-FDD mostly used standard for UMTS that transmits and receives independently and same time.
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The frequency allocation of UMTS-FDD is shown is diagram X. Majority region around the world uses the band 1920-1980 MHz for uplink and 2110-2170 MHz for downlink in WCDMA-FDD shown in Diagram 3.1.
For RF designing of UMTS the RF designer must know two things i.e. UMTS is power-limited on the downlink and UMTS is noise-limited in the uplink. The RF designer should take care that each user getting suitable power and least noise in the uplink from other cells in the network. UMTS uses same frequency in all cells unlike GSM which uses different frequencies. Same frequency at each cell makes UMTS radio planning so different as compare to GSM and the tactics of GSM planning do not applied in case of UMTS. This is more critical especially for indoor coverage, in GSM common way to cover indoor areas by boosting up the power of base station or with the use of different carrier frequencies. For the case of UMTS this planning is not valid because all networks have two or three carriers in total as a resource for present and future. The only possible ways for UMTS indoor planning is to control transmitting power from base station and controls the noise. The UMTS RF channel is different from GSM. UMTS uses WCDMA and WCDMA is a spread spectrum signal. In WCDMA the narrow band information of the each user is spread in the whole spectrum as a consequence the data of each user converted into wider bandwidth. The data which is converted on wider bandwidth becomes less sensitive from narrow-band interference. Improved spectral efficiency in UMTS capable of providing peak downlink data rates up to 2 Mbits/s which are higher than GSM. UMTS offers compatibility with the older
2110 MHz 2170MHz
1920 MHz 190 MHz Duplex Distance 1980 MHz
Downlink Band (UMTS) 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5MHz
Uplink Band (UMTS) 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5MHz
Diagram 3.1 UMTS uplinks and downlink frequencies band
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existing GSM systems i.e. the existing sites and equipments can be used for UMTS which reduces operator CAPEX cost. In practical scenarios all users may not get peak data rate every time. This might be environmental propagation and economic of network and this is worst in congested and heavily populated environment.
3.1.2 High-speed Downlink Packet Access (HSDPA) HSDPA stands for high speed downlink packet access that can be deployed on existing 3G networks. HSDPA can deploy on the same UMTS channel and it uses the head portion of power that is not utilized by the UMTS traffic. The new modulation scheme of HSDPA improves the downlink peak data rates and spectral efficiency. The improvement in spectral efficiency and data rates increases the system capacity. This improvement is based on adaptive modulation and coding method, fast scheduling function and fast retransmission. In HSDPA link adaption is the capability to select the modulation scheme according the radio link. The coding rate varies between ¼ and ¾ depending on the radio link condition with fixed spreading factor. Link adaption capability for HSDPA to ensure that higher data rates to be delivered to user. User which have good radio signal link typically located near to base station higher coding rate is selected which provides higher data rates and users which are far from base station near to cell edge than lower coding rate is selected. In HSDPA the scheduling of transmission of data packets is performed in the base station. The reason for fast scheduling of transmission is that it is done base station which is near to air interface and short frame length is required. Retransmission occurs due to interference from the mobile terminals. In WCDMA networks these retransmission requested are responded by RNC which take more time. For the case of HSDPA retransmission requests are responded in the base station which provides faster response. Moreover incremental redundancy is introduced which extracts the bits which are correctly transmitted from the original transmission, this decreases the retransmission requests in future. New Transport channel type is introduced in HSDPA to carry user data called high speed downlink shared channel (HS-DSCH). HS –DSCH carry user data in bursty manner that creates efficient use of radio frequency resources. HSDPA offers peak rates up to 14 Mbps in a single 5 MHz channel. Beside the peak data rate HSDPA have a capability to provide average packet data throughput capacity to more users on a single radio carrier. Moreover the downlink transmission delay is less in HSDPA which is required in many applications typically a guaranteed short delay is required for games and many more applications.
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3.1.3 Long Term Evaluation (LTE) Long Term Evaluation (LTE) is enhancement in Universal Terrestrial Radio Access (UTRA) which is capable for providing higher data rates, improved spectral efficiency and many more innovative features which overcomes the problems of increased data traffic. LTE is capable for providing throughput 100Mbps in downlink and 60 Mbps in the uplink. The spectral efficiency of LTE is improved with the use of new and enhanced air interface i.e. E-UTRA. LTE uses E-UTRA (Evolved Universal Terrestrial Radio Access) air interface which is enhanced version of UTRA. LTE uses multicarrier Orthogonal Frequency Division Multiplexing (OFDM) for downlink which is robust against while dealing with multipath interference and supports advanced techniques like frequency channel domain channel-dependent scheduling and MIMO features. Moreover the use of OFDMA providing an efficient method to overcome the problem of multipath delay spread. LTE supports data modulation schemes QPSK, QPSK, 16QAM, and 64QAM in the downlink. For the case of uplink Single Carrier-Frequency Division Multiple Access (SC-FDMA) is used for uplink to overcome the problem of very high peak to average power ratio (PAPR) which occurs in normal OFDM. For high PAPR expensive power amplifiers are require which increases the cost and less efficient. LTE uses BPSK, QPSK, 8PSK and 16QAM supported modulation schemes for uplink. Moreover E-UTRA supports variable bandwidth according to the requirements. LTE‟s UTRA channel bandwidth can be selected between 1.25 MHz and 20 MHz which provides some flexibility in selection of bandwidth and make it more efficient use of bandwidth as compare to UTRS‟s in which the fixed 5 MHz channels are used. LTE supports MIMO which capable of transmitting multiple streams simultaneously with multiple antennas are used at transmitter and receiver. The use of MIMO in LTE increases the throughput in multiplicative way. With high data rates LTE is capable of performing two-dimensional resource scheduling (between time and frequency axes) creating ability to handle multiple simultaneous users. In same slot up to 50 users can be scheduled. The increased handling of simultaneous user is providing more benefits for handling high traffic. LTE protocol architecture is simple as compare to UMTS and other systems. It is based on shared channel based and compatible with VoIP services. LTE is compatible with other system making it more flexible when communicating with other systems and roaming services. Finally it is concluded that LTE is capable of handling high data traffic demand with excellent network structure with high speed, improved spectral efficiency, simplified structure, multi users handling, MIMO services, simplified roaming services worldwide making it essential solution.
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3.2 IEEE 802.11 Standards
IEEE 802.11x standards are used for WLAN to provide wireless connectivity. 802.11 standards are capable for supporting high data traffic. Introduction of 802.11 standards switches users from cable to wireless connectivity with several good features like wireless networking (ad-hoc networks), mobility and high speed connectivity. People can use their laptops or mobile easily in schools, airports, offices and many places without having a cable. Unlike wired network which are used for permanent connections or installation, 802.11 are provides facility to temporary connections as well. This temporary connection features provides more business options for guest of visitors users. Installation of single 802.11 based networks on building supports guest users in simple way. This feature of 802.11 makes it cost efficient solutions for handling more users without installation of more devices. Moreover there is no need to alter the wiring of office and long installation is required which is normally required in wired networks. 802.11 operates in ISM (Industrial, Scientific and Medical) frequency band in which no license is required when using 802.11 standards and it is used by multiple users.802.11 standards are categorized into variety of standards which are differentiated with a letter suffix after 802.11 Commonly used standards for 802.11 are 802.11a, 802.11b, 802.11g and 802.11n. These standards are differentiated according to different features and launched in different times which are shown in Table 3.1. 802.11a 802.11b 802.11g 802.11n
Peak Data Rate
(Mbps)
54
11
54
150
Operating Frequency
(GHz)
5
2.4
2.4
2.4 or 5
Bandwidth (MHz)
20
20
20
20 or 40
Table 3.1 802.11 standards
802.11b launched in 1999 which operates in 2.4 GHz frequency spectrum. 802.11b capable of providing peak data rates of 11 Mbps and practically it provides 4-7 Mbps. 802.11b standard is famous and lease expensive standard. In 802.11b the speed of transmission easily affected by the interference from cell phones and Bluetooth operated devices. For the case of 802.11a it was introduced in 2001 to provides higher data rates. 802.11a generates peak data rates up to 54 Mbps rates and average throughput
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is14-21 Mbps. 802.11a operates in 5 GHz frequency band, more expensive than 802.11b standards and not compatible with 802.11b. 802.11g is the combination of 802.11a and 802.11b. This standard combines the features of 802.11a and 802.11b. It uses the operating frequency of 802.11b i.e. 2.4 GHz and data rate similar to 802.11a standard. In addition 802.11g, it is compatible with 802.11b standard. 802.11n as the new standard introduced with new technologies considered into account for getting higher data rates as compare to previous 802.11 standards. The data rate is improved 5 times higher than the older standards of 802.11 with enhanced coverage. This high speed standard also provides compatibility option to previous standards. The introduction of MIMO technology in 802.11n standards making it to generate more data rates as compare to previous 802.11 standards. MIMO technology is capable of handling multiple inputs and multiple outputs which increases data rates. Moreover 802.11n supports 20 or 40 MHz channel bandwidth, in 40 MHz channel bandwidth two 20 MHz channels are merged. Increasing the bandwidth of channel means more bandwidth per access point. 802.11 based networks support three types of topologies AP-based (Infrastructure Mode), peer to peer (Ad-hoc Mode) and point to multipoint. In Infrastructure Mode, access point is installed to provide a „hot spot‟ through which users access the internet. The access point supports multiple users. This access point is connected with server with cable. Each access point is the controller of cell which is responsible for transmit and receive signals from end user like laptops or mobiles. Peer to peer (Ad-hoc Mode) do not require access point for communicating among 802.11 based devices. It is simplest and quick user generated network in which user are communicating directly with each other in a cell. This is useful when creating small and quick time network like a group of networks. In point to multipoint bridge mode single unit is connected with multiple units. This mode normally used to connect multiple LAN in buildings which are located far from each other via line of sight communication. High transmitters are required for this network topology with clear line of sight conditions among buildings. 802.11 based networks are growing and replacing wired network like LAN. These networks are present in offices, schools, hospitals, airports. Moreover they are robust for handling high data traffic especially for indoor environments where many obstacles are presents. Introduction of mobile broadband technology in which data traffic demand is high, for this high demand 802.11 based networks essentials and cost economical.
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Chapter 4
4 Techno-Economics of Wireless Indoor Solutions
In this chapter techno-economic methodology and related models are discussed. Starting from the techno-economic model which covers the overall understanding of techno-economic analysis and after that each model which are involved in techno-economic analysis are explained.
4.1 Techno-Economic Model
Estimation of network cost involves several stages to which are interconnected and dependent. It is necessary to design network for estimating cost. For techno-economic analysis several simple and complex models are involved. For better understanding techno-economic model is sub-divided into general models, network designing and cost models which is shown in Diagram 4.1.
Diagram 4.1 Techno-economic Model
The techno-economic process is start from the general models. For general models it is necessary to know radio access technology, type of indoor solution, coverage area, coverage environment and traffic demands which are used to determine
20
coverage and capacity estimations of indoor solution. General models uses link budget and propagation models to estimate the cell radius of indoor solution for specific environment type. Once the cell radius is achieved the number of base stations with respect to coverage wise can be calculated. Moreover depending on the traffic demand and capacity from specific radio access technology through which number of base stations capacity wise is calculated as well. General models are more related to determining the coverage and capacity estimations for specific wireless indoor solution. After determining the specific indoor solution‟s coverage and capacity characteristics the need is to dimension and design a network that fulfils both coverage and capacity requirements. Network designing uses inputs from the general models and dimension the network so that it fulfils both coverage and capacity requirements. The network designing method estimates the quantity of base stations, network elements and amount of spectrum required for network. The elements of network depend on type of indoor network. The quantity of base stations and network elements obtained from network designing step helps to determine the cost of network. The cost of network is now calculated by cost structure assumptions and network dimensioning results. The cost model is responsible for estimating to capital expenditures (CAPEX) and operational expenditures (OPEX) for indoor solution. Net present analysis (NPV) is also calculated for comparing with different indoor solutions. The techno-economic model describes the overall method for estimating the cost of wireless indoor solutions provided by different inputs. The description for each sub-model is described below with detail.
4.2 General Models Base station coverage and capacity characteristics are important for designing a network. The coverage depends on the transmission power from the base station and environment type. In dense environment the coverage of base station degrades as compare to open environment. The issue is critical especially for indoor environments where several types of obstacle are present which attenuates the signal. The coverage of base station is vary according to the environment, dense environment have small cell radius as compare to open environment. The need is to calculate the cell radius according to the environment type so that better coverage is obtained. Moreover for dealing with indoor environments an indoor propagation model is selected so that it helps to determine the cell radius. From capacity point of view base station capacity depends on the radio access technology and amount of spectrum. The capacity of base station can be increased by using efficient radio access technology or increasing the amount of spectrum. Mostly wireless indoor solutions are designed so that they can use single carrier. Both coverage and capacity characteristics need to be know so that it helps to design network. In this section models for prediction of coverage and capacity inside the building for indoor solution is covered. An indoor propagation loss model which helps to calculate
21
the theoretical cell radius of base station according to environment is discussed. Once the cell radius is determined number of base stations for covering area is estimated. The number of base stations with respect to capacity is also calculated from traffic demand and radio access technology capacity.
4.2.1 Link Budget
In order to determine the maximum allowable path loss between base station and mobile station link budget calculations are done. In link budget calculations standard values and parameter are considered to estimate the maximum allowable path loss. Link budget‟s components are shown in Diagram 4.2.
Diagram 4.2 Link Budget Components
For estimation of maximum allowable path loss in uplink and downlink detailed link budget analysis is required by setting some parameters and using standard values. Link budget calculations are done in [20] to estimate the maximum allowable path loss. Same link budget is considered in this thesis to determine the maximum allowable path loss. The link budget calculation is necessary for downlink and uplink for satisfying two way communications. The link budget for downlink is shown in table 4.1.
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Parameter Unit Symbol Comments BS Transmitter
BS Transmit Power dBm A Input parameter
Feeder Losses dB B Input parameter
BS antenna gain dBi C Input parameter
EIRP dBm D A-B+C
MS Receiver
MS antenna gain dBi E 0 dBi typical for mobile station
MS noise figure dB F value according to standard
Noise power dBm G (-174 dBm/Hz) + F+10*log(bandwidth)
Interference dBm I Use suitable value
Interference+noise dBm J 10*log(10I/10) + 10G/10
Target SNR dB K Use value according to the requirement
Mobile sensitivity dBm L J + K
Channel
Log-normal shadow Fading
dB M Use suitable value typical 10 dB
Multipath Fading Margin
dB N Use suitable value typical 6 dB
Body loss dB O Use suitable value typical 3 dB
Total Margin dB P M+N+O
Minimum receive level
dBm Q L + P
Maximum allowable path loss
dB R D-Q
Table 4.1 Link budget for downlink
For the case of uplink base station and mobile station are interchanged in position. Mobile station is transmitting signal to base station for communication. The link budget for uplink is shown in table 4.2.
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Parameter Unit Symbol Comments MS Transmitter
MS Transmit Power dBm A Input parameter
BS antenna gain dBi B Input parameter
EIRP dBm C A+B
BS Receiver
BS noise figure dBi E 0 dBi typical for mobile station
BS passive losses dB F value according to the devices
Noise power G (-174 dBm/Hz) + E+10*log(bandwidth)
Interference dBm H
Interference + Noise I 10*log(10H/10) + 10G/10
SNR Requirements dB J Use suitable value
BS antenna gain dBi K Use according to the device
Mobile sensitivity dBm L F + J +I –k
Channel
Log-normal shadow Fading
dB M Use suitable value typical 10 dB
Multipath Fading Margin
dB N Use suitable value typical 6 dB
Body loss dB O Use suitable value typical 3 dB
Total Margin dB P M+N+O
Minimum receive level
dBm Q L + P
Maximum allowable path loss
dB R C-Q
Table 4.2 Link budget for uplink
4.2.2 Propagation Models
The propagation models used to predict the path loss for indoor scenarios. Several models are present to determine the path loss for indoor and outdoor scenarios.Two models are discussed free space model and path loss slope model. Free space model is used for open area while path loss slope model is especially for indoor scenarios where lot of obstacles present. These propagation models help to determine the antenna radius.
4.2.2.1 Free Space Model
Free space model is simple model to calculate the path loss of open environment with ideal conditions. The path loss for free space is obtained using free space loss formula which is,
Free space loss (dB) = 32.44+20logF+20log D (F is frequency and D is the distance between the transmitter and receiver in Km)
24
4.2.2.2 Path Loss Slopes (PLS) Model
Path loss slopes model [20] is widely used model for indoor environments where many types of obstacles are present. This model is based on the empirical analysis of enormous number of measurements in different scenarios. The path loss slope (PLS) is derived by averaging the measurement samples taken in different environment, frequencies and scenarios. The path loss can be calculated from below equation.
Path loss (dB) = Free space loss @ 1m + PLS × log(distance) Where free space loss @ 1 m is achieved by free space model, PLS is path loss slopes coefficient. PLS value is different for each building or environment scenario. Common PLS values [20] are shown in Diagram 4.3.
Diagram 4.3 PLS values for different environment [20]
4.2.3 Cell Radius Estimation
This model calculates the cell radius of base station for specific type of environment. Cell radius depends on the environment; cell radius in dense environment is small when comparing with open area environments. The cell radius[20] for specific environment is calculated by give equation.
Cell radius (m) = 10(APL-PL1m)/PLS
Where APL is maximum allowable path loss obtained from link budget analysis, PL1m is the free space path loss at 1m calculated from free space modeling and PLS is path loss slope coefficient for specific environment type achieved from path loss slope model.
PLS constants for different environments
open environment,
few obstacles, parking, garage, convention center
Moderately open environment, low to medium number of RF
obstacles
factory, airport, ware house
Slightly dense environment, medium to large number of obstacles
shopping mall , off ice that is 80% cubicle, 20% hard wall .
Moderately dense environment, medium to large number of RF
obstacles
off ice that is 50% cubicle and 50% hard wall .
Dense environment , Large number of RF obstacles
Hospital , off ice that is 20% cubicle and 80% hard wal l .
Environment 900MHz 1800/2100MHz
33.7
35
36.1
37.6
39.4
30.1
32
33.1
34.8
38.1
Indoor radio planning, Morten Tolstrup
25
The cell radius is required to calculate for both uplink and downlink separately. After calculating the cell radius for uplink and downlink both results are compared and cell radius that‟s fulfils uplink and downlink can be calculated by taking the minimum cell radius which is further explained in diagram 4.4.
4.2.4 Area Coverage
Area coverage analysis determines that how many number of base station required that provides coverage for specific area. The number of base station varies according to area size and environment. The number of base stations for covering specific area can be obtained by dividing the total coverage area with area of the cell.
Number of Base Stations (coverage) = Total coverage area / Cell Area
4.2.5 Placement of base stations Once after calculating the number of base stations required for specific environment type the need is where to place the base stations. High attenuated environment requires more number of base stations as compare to low attenuated environments. For theoretical environment like uniform RF attenuation in all direction inside the building, inter-antenna distance must be 2×Antenna Radius for complete coverage but this is not suitable for practical scenarios. For providing coherent coverage in a building or any area the inter-antenna distance should be less than 2×Antenna Radius. Theoretical correct inter-antenna distance for omni-directional antenna is 1,41×Antenna Radius, this inter-antenna distance provides coverage overlap between the antennas that covers some practical scenarios and provides good indoor coverage.
Uplink’s Cell Radius
Downlink’s Cell
Cell Radius
=
Minimum (Uplink’s Cell Radius, Downlink
Cell Radius)
Diagram 4.4 Cell Radius for specific environment type
26
4.2.6 Capacity (Number of Base Stations)
Beside coverage requirements it is necessary to consider capacity measures as well. The network must be capable of fulfilling traffic demand requirements of mobile users as well. For this reason number of base station are required to fulfil the capacity requirements for certain area. Number of base station for satisfying the demand is calculated by dividing the demand with capacity of network.
Number of Base Stations (capacity) = Demand / Network Capacity
4.3 Network Designing
Wireless indoor network consists of multiple base stations which are dependent on coverage and user demand needs. The requirement of coverage and user demand depends on the scenarios and environments. Coverage which is initial parameter that describes the wireless network which area is required to cover. Coverage is dependent on the area to cover, environment architecture and type of materials used in buildings. Large areas required more base stations for covering area, for highly dense environment signal from base station is attenuated from the obstacles and more base stations are required to cover. Beside coverage user demand satisfactions is need to be consider for deploying wireless networks, when deploying wireless network user demand is necessary to estimate which helps to dimension a network in a efficient way. High demand scenario influences the network, more capacity need to be generated from base station that fulfills the demand requirements. For wireless networks capacity of the network can be increased by adding more number of base stations, increase spectral efficiency and use more spectrums. For highly user demand scenarios it motivates wireless network to add more base stations or use higher spectral efficiency radio access technique or use more spectrum. It is not necessary that spectrum is
Radius
Inter-Antenna Distance = Antenna Radius × 1,41
Diagram 4.5 Place of antenna with certain coverage overlap for full coverage
27
increased in each indoor solution type like Femtocell and Picocell in which single carrier is used, so only possible way for increasing capacity of these type of network to add more base stations or use high spectral efficient radio access technique. Coverage and capacity requirements for wireless networks are the mandatory points, it is necessary to be fulfilled. For coverage and capacity requirements network is designed so that it fulfills the coverage and capacity requirement. The network designing is different according to the architecture and operation of indoor solution. The network designing for Femtocell, Picocell and WLAN is almost similar; these are small base stations or access points which act as an individual cell in which only possible way to increase the network capacity by adding base stations or by using high spectral efficient radio access technology. For the case of DAS the network designing is complicated with the presence of cables and other DAS elements. Moreover the capacity of DAS network can be increased by using high spectral efficiency radio access technique and adding more spectrums. In this thesis active DAS is considered into the account. The network designing of indoor solutions are described below.
4.3.1 Femtocell, Picocell and WLAN Case
The network designing for Femtocell, Picocell and WLAN is sample as compare to DAS. Two conditions must be fulfils for a network i.e. a network capable of providing coverage and capacity requirements. It is not necessary the number of base stations with respect to coverage and capacity are always same; they are dependent on the coverage and demand requirements. For any network it is useless if it is fulfilling one condition either coverage or capacity. To achieve both conditions a strategy is required to make network capable of providing coverage and capacity. The number of base station with respect to coverage and capacity obtained from general models are needed to compare and by selecting the maximum number of base station it will make network to provide both conditions. It can be further explained in Diagram 4.6.
Number of base stations
=
Maximum [Number of base
stations (coverage), number of
base stations (capacity)]
Number of base stations
(coverage)
Number of base stations
(capacity)
Diagram 4.6 Number of base stations for satisfying coverage and capacity requirements
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4.3.2 Active DAS Case
The network designing of Active DAS is different as compare to Femtocell, Picocell and WLAN. For the case of active DAS coverage is enhanced by installing more number of antenna elements and active DAS elements. In DAS there is single base station and one of the possible ways to increase the capacity is to add more carriers or amount spectrum unlike Femtocell, Picocell and WLAN in which multiple base stations or access points can be installed. The need is to calculate how much spectrum or number of carriers required with single base station that fulfils the low and high level demand.
Amount of Spectrum or number of carriers = Demand / Capacity of Network
Moreover it is necessary to calculate the elements of Active DAS, length of cables and amount of spectrum that satisfies both coverage and capacity requirements. The method for calculating Active DAS elements and length of cables required are explained below:
4.3.2.1 Elements for Active DAS Active DAS consists of Main unit, expansion unit, remote unit and antenna elements. For single active DAS system it can maximum supports or can connect elements are given below: Main Unit = 1 Expansion Unit = 4 Remote Unit = 32 Antenna Elements = 32 (without power splitter) Power splitter is connected to remote unit which splits the power into multiple antennas which improves the coverage. The method for calculating the number of antenna elements required for active DAS is shown in diagram 4.7. The elements in active DAS is dependent on the number of antenna elements required for active DAS and it is input of this algorithm. For active DAS single main unit exists with multiple expansion and remote unit. Active DAS supports maximum 32 antenna elements without any power splitter. If the number of antenna elements are less than or equal to 32 then no power splitter is required for covering the building and the other hand the number of antenna elements exceeds from 32 then power splitter is required for providing coverage in building. Power splitters come in different sizes like 1 into 2, 1 into 3, 1 into 4 etc.
29
4.3.2.2 Cable Types and length The cables used in active DAS system are fiber-optic cable, thin co-axial (0,5 inch) and coaxial cable or CAT 5 cables. The fiber-optic cable used for connecting the
Start
No. of
antenna
elements
No. of
antenna
elements ≤32
No. of expansion unit
=
(No. of Antenna
elements×4) / 32
No. of Remote units
=
No. of antenna
elements
No. of expansion unit = 4
No. of remote unit = 32
No. of power splitters
=
(No. of antenna
elements-32) /
(branches of splitter: 2
or 3 or 4)
End
Diagram 4.7 Flow chart for calculating active DAS elements
Yes No
Traffic
Demand
Amount of Spectrum
or Number of Carriers
Power Per Carrier
Link Budget
Calculations
30
main unit with expansion unit, expansion and remote unit connected via CAT 5 cable or coaxial cable and antenna are connected to remote unit with thin coaxial cable (0,5 inch). The length of fiber optic cable depends on the placement of main unit and remote units. Main unit is normally placed on ground floor in a building as well as one or two expansion units also places in that floor depending on the size of the building. The remaining expansion units can be placed in middle of the building as a consequence the length of fiber optic cable calculated by the distance between main unit and expansion unit. CAT 5 or coaxial cable length depends on the distance between the remote unit and expansion unit, the length of CAT 5 or coaxial cable is long as compare to fiber optic cable. The length of thin coaxial cable that connects remote unit with antenna elements is small as compare to other cables used in the active DAS.
4.3.2.2.1 Thin Coaxial Cable (0,5 inch) Once the active DAS network element placed the length of cable can now easily determined. Starting from the thin 0,5 inch coaxial cable that connects antenna element and remote unit, normally this cable has a length of 10m so the length of thin cable is:
Length of thin cable (0,5 inch) = 10m × number of antenna elements
4.3.2.2.2 Fiber optic Cable The length of fiber optic cable depended on the distances between the main unit and expansion unit. For active DAS maximum 4 expansion units can be connected with main unit so the total length of fiber optic cable is sum of the lengths of all fiber optic cables that connects main unit and expansion unit.
Length of fiber optic = length (fiber 1) + length (fiber 2) + length (fiber 3) + length (fiber 4)
4.3.2.2.3 Coaxial or CAT 5 cable The length of coaxial or CAT 5 cable depends on the number of antenna elements for covering the building and placement of antenna elements. The coaxial cable is used for connecting the remote and expansion unit. The total length of cable is the sum of all cables that connects remote unit and expansion unit.
Length of coaxial cable = l1+l2+l3+………………..+ln Where: l = length of coaxial cable that connects remote unit and expansion unit and n= number of cables
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4.4 Cost Models
Cost of network is important parameter that needs to be considered due to high competitions. The cost of network directly depends on coverage and capacity requirements. Large coverage area requires more base stations and network elements which influences the network cost, moreover it depends on the environment type as well, denser area requires more stations as well which increases the cost of network. The another factor for affecting the network cost is the traffic demand requirements, higher traffic demand require more capacity from network which raises the network cost as well. As a consequence network cost depends on network dimensioning results. The network cost also dependent on the type of indoor solution. The network cost is different for each indoor solution according to the network architecture properties. In this section cost structure and cost models are discussed. The cost structure represents that how cost is distributed among different indoor solutions with their assumed values and the cost models estimates deployment and operational costs for network. These models help for comparing the cost of different indoor solutions for a particular scenario. The cost models use the input from network designing method and cost structure to provide Capital Expenditures (CAPEX) and Operational Expenditures (OPEX) for indoor network. The cost model for Femtocell, Picocell and WLAN are same but for the case of Active DAS separate model is used to determine the CAPEX and OPEX. After CAPEX and OPEX estimation Net Present Value (NPV) is done which includes both CAPEX and OPEX to provide comparison among different indoor solutions.
4.4.1 Infrastructure Cost
In this section cost structure assumptions for Femtocell, Picocell, WLAN and active DAS is presented. The cost parameters assumptions are based on own assumptions and from the reports [9][1], the prices may vary in real. The capital expenditure (CAPEX) and operational expenditure (OPEX) are considered for cost analysis. The cost structure assumptions are divided into two groups : access point and distributed antenna case. The architecture for Femtocell, Picocell and WLAN is almost similar with smaller variation so for this reason they are placed in access point‟s group. The CAPEX are OPEX for Femtocell, Picocell and WLAN are shown in Table 4.5.
Capital Expenditures (k€) Operational Expenditures (k€)
BS RNC Transm. Site Trans. O & M Power
Picocell 3 3.9 2 2 2 0.9 0.1
WLAN 1 1 0 1 1 0.4 0.01
BS BSC Hardware
BSC Software
Installation Support & Maintenance / year (12% of original price)
Femtocell 0.3 0.003 0 1.2 0.1806
Table 4.5 CAPEX and OPEX assumptions for Femtocell, Picocell and WLAN
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The network architecture of active DAS is complicated as compare to Femtocell, Picocell and WLAN. For active DAS more things need to consider into account for cost analysis. The assumptions of prices for active DAS are shown in Table 4.6.
DAS’s Capital Expenditures (k€)
BS RNC Transm. MU EU RU Antenna Thin Coaxial (100m)
Coaxial -RG 6 (100m)
Fiber (100m)
Single Carrier
15 4 5 3 1 0.5 0.3 0.32 0.04 0.9
Additional Carrier
5 4
DAS’s Operational Expenditures (k€)
Transm. Site O&M Power
Single Carrier 5 3 5% of CAPEX 2
Additional Carrier
1
Table 4.6. CAPEX and OPEX assumptions for DAS
4.4.1.1 Capital Expenditure The price for Picocell, WLAN and Femtocell assumed as 3k€, 1k€ and 0.3k€ respectively. For the case of active DAS, the price for single carrier base station is considered as 15k€, additional carriers can be added to macro base station which costs 5k€ per additional carrier. Cellular base station requires a radio network controller for each wireless indoor solution. The price for network controller for macro base station is assumed 4k€ and for additional carrier is 4k€. Moreover WLAN require an access gateway and a router is required instead of radio network controller and the price per WLAN is assumed as 1k€. Leased lines or E1 lines of 2 Mbps is considered as transmission solution for macro cell and Ethernet/DSL is assumed for additional capacity. For Femtocell, Picocell and WLAN a simpler IP network (Ethernet/DSL) is considered. The cost of backhaul transmission for macro base station is assumed as 5k€ per base station, 2k€ per base station is for Picocell base station. No capital expenditures are included for Femtocell and WLAN. The cost for site installation for Picocell, WLAN and Femtocell assumed as 2k€, 1k€ and 1.2k€ respectively. Build out for active DAS is complicated as compare to Femtocell, Picocell and WLAN which requires 3 types of cables and 4 network elements.
33
4.4.1.2 Operational Expenditure In operation expenditure it is difficult to define exact O&M. In this thesis it is assumed that O&M is derived from percentage of the price of equipment. For macro base station which have higher equipment cost, O&M for macro base station is assumed to be 5% of CAPEX for base and radio network controller price. Picocell, WLAN and Femtocell the O&M are 10%, 20% and 12% respectively due to low cost of equipment cost. Electricity for DAS is assumed as 2k€ per year and for Femtocell, Picocell and WLAN electricity cost is too low as compare to macro base station in active DAS. For cost of backhaul transmission for macro base station which is used in active DAS is proportional to number of connections. For single-carrier macro base station the cost of transmission line is assumed to be 5k€ and for additional carriers DSL based solution is supposed to increase the capacity. The price of additional carrier for macro base station is supposed to be 1k€. The same DSL solution is assumed as well for Picocell, Femtocell and WLAN. Site leasing for macro base station is assumed 3k€ per year and for Femtocell, Picocell and WLAN no site leasing is considered.
4.4.2 Femtocell, Picocell and WLAN case
The cost model for Femtocell, Picocell and WLAN is simple as compare to active DAS which is shown in Diagram 4.8.
The cost model for Femtocell, Picocell and WLAN depends on the number of base stations which are obtained from the network designing of Femtocell, Picocell and WLAN. This cost model uses the inputs i.e. number of base stations required for a network and cost structure assumptions. The cost of the network is estimated by calculating the Capital Expenditures (CAPEX) and Operational Expenditures (OPEX). The cost model provides the CAPEX and OPEX cost for the Femtocell, Picocell and WLAN. The CAPEX which is the investment cost of network is calculated by taking the inputs from network designing method which determined the quantity of network elements
Cost Model
(Femtocell,
Picocell and
WLAN)
Cost Strucutre
Asumptions
Required No. of
access points for
satisfying coverage
and capacity
CAPEX of Network
OPEX of Network
Diagram 4.8 Cost Model for Femtocell, Picocell and WLAN
34
and using the cost structure assumptions. So the CAPEX is calculated by multiplying the number of base stations with the summation of cost of access point, radio network controller, access point installation and transmission cost. The equation for calculating the CAPEX cost is shown below: CCAPEX = n× (C ACCESS POINTS + CRADIIO NETWORK CONTROLLER + CACEES POINT INSTALLATION+ CTRANSMISSION)
; C = Cost and n=number of access points / base stations The OPEX cost depends on transmission, site leasing, O&M and power. The OPEX is calculated in similar way as CAPEX is calculated i.e. by multiplying the number of base station with summation of operation costs involved i.e. transmission, site leasing, O&M and power. The equation for calculating OPEX is described below:
COPEX = n× (CTRANSMISSION + CSITE LEASING + CO&M + CPOWER) ; C = Cost and n=number of access points / base stations
4.4.3 Active DAS case
The cost model for active DAS is more complex than Femtocell, Picocell and WLAN. This cost model is depends on many inputs which obtained from network designing of active DAS. The cost model for active DAS is shown in Diagram 4.9. The inputs for cost model for active DAS are number of main units (typical 1), expansion units, remote units, power splitter (if used), length of cables (0.5 inch coaxial, RG 6 coaxial cable and single mode fiber optic), base station, radio network controller, amount of spectrum or number of carriers. This Cost model uses cost structure assumptions and provides the CAPEX and OPEX for active DAS network.
The CAPEX for active DAS is complex as compare to Femtocell, Picocell and WLAN. The CAPEX for active DAS is calculated by sum of costs of single base station, radio
Cost Model
(Active DAS)
Cost Strucutre
Asumptions
* No. of antenna
elements
* No. of
Expansion Unit
*No. of Remote
Units
*Main Unit
*Length of cables
*Amount of
spectrum or
number of carriers
CAPEX of Network
OPEX of Network
Diagram 4.9 Cost Model for active DAS
35
network controller, transmission cost, length of cable lengths and number of active DAS elements obtained from network designing method which is further explained in equation below: CCAPEX = CBASE STATION + CRADIO NETWORK CONTROLLER + CTRANSMISSION + n×CMAIN UNIT + n×CEXPANSION UNIT + n×CREMOTE UNIT + n×CANTENNA ELEMENTS + L×CRG-6 COAXIAL CABLE + L×C0.5 INCH COAXIAL CABLE + L×CRG-6 COAXIAL CABLE + L×CSINGLE MODE FIBER OPTIC CABLE
; C=Cost, n= number or quantity and L=length of cable OPEX costs for active DAS is obtained by summation of transmission cost, transmission cost of additional carriers, site leasing cost, O&M(5% of CAPEX) and power cost. COPEX = CTRANSMISSION + CSITE LEASING + CO&M + CPOWER ; C = Cost
4.4.4 Net Present Value (NPV) For comparing the different deployment options the CAPEX and OPEX for each solution need to consider in the analysis. For comparing cost of different indoor solutions Net present value of CAPEX and OPEX need to calculate. The NPV is calculated by standard formula.
Where values are cash flows, n is the number of cash flows and i is the discount rate.
36
37
Chapter 5
5 Case Study Assumptions
For this thesis case study is included as a primary methodology for comparing different types of indoor solutions. For this case study some assumptions are made to investigate the technical and economical performance.
5.1 Scenario For this thesis a building is required as a scenario in which all four systems will deploy to compare the technical and economical results. ‘Mobile Indoor Components-MIC Nordic’ is a vendor for deployment indoor solutions suggested to take his building where they are working project. The building they suggested is an office building called Skatteverket‟s building located at Korta Gatan 10, Solna, Stockholm, Sweden. For this thesis the Skatterverket‟s building is considered as a scenario where all systems will deploy. In Skatteverket‟s building there are 8 floors in total with two floors in basement. In dimension wise this building has 100m length and 50m in width. The architectural structure of building is shown in Diagram 5.1. 100m
50m
Entrance In diagram 1 the shaded area represents the free area without any obstacles till the highest floor of the building. Two rectangular areas are halls, computer rooms and conferences rooms and they are also free areas and the remaining area contains offices with wood or glass portioned. The floor plan of this building is mainly categorized into 3 types which are given below:
Diagram 5.1 Skatteverket’s Building Architecture (Top View)
38
Type 1: Parking Area in the extreme basement level. This area contains 10% concrete walls and 20% of offices are present. This type is considered as moderately open environment from low to medium number of RF obstacles. Type2: An office area with 80% cubical of wood and 20% of concrete walls. Wood has smaller attenuation than concrete walls. The environment of this floor is considered as slightly dense environment having medium to large number of obstacles. Type 3: Moderately dense environment from medium to large number of RF obstacles contains 40% of concrete walls and 60% of cubicles. In Skatteverket‟s building the one floor is type 1, 3 floor plans belongs to type 2 and remaining 4 are of type 3.
5.2 Traffic Demand In Skatteverket‟s building it is assumed that 600 employees that uses smart phone and laptops. The smart phone normally used for low usage applications like messaging, reading emails etc. but laptops usage is quite high like streaming of video, downloading of software‟s etc. as compare to smart phone. Two levels of demand are assumed „Low level demand‟ and „High level demand‟ to check the flexibility of network. It is not suitable to deploy or modify network every time with the increase of demand. The network must be capable of handling current users with some variations in users as well. The data usage per user and per month in GByte for low level demand is considered as 2.2 and high level is 24.2. Both level of demand is considered for techno-economic analysis with full coverage from initial.
5.3 Spectral Efficiency In this thesis four radio access technologies UMTS, HSDPA, LTE and 802.11n are considered. Moreover all the radio access technologies are considered as single input and single output (SISO). The peak spectral efficiency of UMTS, HSDPA (SISO), LTE (SISO) and 802.11n are 0.4 bps/Hz, 2.8 bps/Hz, 5 bps/Hz and 3.75 bps/Hz respectively. Peak spectral efficiency achieved with ideal conditions. Spectral efficiency is depended on the distance between the base station and mobile station, spectral efficiency is high when mobile is near to base station and vice versa. In practical scenario it is difficult to get peak spectral efficiency all the time due to mobility of mobile. For this thesis average value of spectral efficiencies are considered. The average spectral efficiencies for UMTS, HSDPA, LTE and 802.11n are 0.3, 2, 4 and 1 respectively. In table 5.2 spectral efficiencies, bandwidth and average throughput for UMTS, HSDPA(SISO), LTE(SISO) and 802.11n are shown.
39
UMTS HSDPA(SISO) LTE(SISO) 802.11n
Bandwidth (MHz) 5
5
20
40
Spectral Efficiency (bps/Hz)
0.3 2 4 1
Average Throughput (Mbps)
= Bandwidth × Spectral Efficiency
1.5
10
80
40
Table 5.1 Average throughput with different amount of spectrums and spectral efficiencies
5.4 DAS Type DAS is mainly categorized into two types passive and active DAS. In this thesis the Distributed Antenna System used is considered as active DAS because the size of this building is medium and higher data rates are required which will difficult of passive systems due to more cable losses as compare to active DAS.
5.5 Power per Carrier (active DAS) In DAS system the power per carrier decreases with the increase of number of carriers. This will affect the coverage of DAS. The power per carrier is assumed for different numbers of carrier are given below:
Number of Carriers Power per Carrier (dBm)
1 15
2 11 3 8 4 6,5 5 5 6 4
7 or higher 3
Table 5.2 Power per Carrier for DAS
40
41
Chapter 6
6 Network Dimensioning Results
This chapter covers network dimensioning results obtained from coverage and capacity models. The aim is to identify and analyze the factors which impact the coverage and capacity results of all indoor solutions under different input parameter.
6.1 Coverage
This section represents the coverage results for Skatterverket‟s building. Skatterverket‟s building consists of three types of floor plans according to environment types i.e. open to dense environment which are Type 1, Type 2 and Type 3. One type 1, three type 2 and four type 3 floor plans present in Skatterverket‟s building. For our thesis full coverage required when deploying the network is necessary condition. The coverage results are shown in Table 6.1 with three types of floor plan that represents how many numbers of base stations are required for full coverage for each environment type and in total as well.
* Single Picocell is enough to cover an small building, for our scenarios two picocells covers the building.
Table 6.1 Number of base stations/antenna elements for different type of floors
Picocell capable of providing strong coverage when comparing with other indoor solutions so for each floor type 1 Picocell base station is enough and for our scenario 2 picocells estimated that provides coverage inside Skatterverket‟s building. In total among Femtocell, WLAN and Picocell highest number of base station required for WLAN to cover the building.
6.2 Capacity
In capacity wise analysis is done for all indoor solutions with low and high level demand with full coverage. Moreover radio access technologies UMTS, HSDPA, LTE and 802.11n are considered into account as another input parameter. Femtocell, Picocell and WLAN capacity is increase by adding more base stations but for the case of active DAS the capacity is increased by adding more number of carriers. The capacity wise results are shown in Table 6.2 with different number of spectral efficiencies and demand.
Floor Type
No. of Floors
Number of Base Stations
Femtocell WLAN Picocell
Type 1 1 2 4 1
Type 2 3 2 4 1
Type 3 4 3 5 1
Total Number of Base Stations
for Skatteverket’s building
20
36
2*
42
Table 6.2 Number of base station for different values of spectral efficiencies
6.3 Femtocell, Picocell and WLAN Network
The results for number of base stations are different with respect to coverage and capacity wise. The aim is to fulfill both conditions i.e. full coverage and capacity requirements. For Femtocell, Picocell and WLAN network number of base stations must satisfy both requirements. The results for network are obtained using network designing and the results are shown in Table 6.3.
Table 6.3 Number of base station for different values of spectral efficiencies
6.4 Active DAS Network
For active DAS network more things need to be taken into account. For this network number of antenna elements, main unit, expansion units, remote units and cable lengths are required. For the case of active DAS base stations is replaced with the antenna elements for providing the coverage that connected with single base stations. In DAS the
Standard
SE
Number of Base Stations (low demand)
Number of Base Stations (High demand)
Femtocell WLAN Picocell Femtocell WLAN Picocell
UMTS
0.3
3
-
3
30
-
30
HSDPA
2
1
-
1
5
-
5
LTE
4
1
-
1
1
-
1
802.11n
1
-
1
-
-
1
-
Standard
SE
Number of Base Stations (low demand)
Number of Base Stations (High demand)
Femtocell WLAN Picocell Femtocell WLAN Picocell
UMTS
0.3
20
-
3
30
-
30
HSDPA
2
20
-
2
20
-
5
LTE
4
20
-
2
20
-
2
802.11n
1
-
36
-
-
36
-
43
transmitted power from the antenna is depended on the number of carriers used so for low level demand less carriers are required as a consequence transmitted power is high and hence less number of antenna elements required to fulfills the coverage requirement. For high level demand more carriers are used that declines the transmitted power and more antenna elements are required to cover the same building. The active DAS elements are shown in Table 6.4.
Table 6.4 Active DAS elements for low and high level demand
After determining the number of active DAS elements the need is to place the active DAS elements. For our scenario the main unit is placed on 2nd floor along with two expansion units and remaining two expansion units placed in 5th floor. It is assumed that the main unit and expansion units located in the center of floor. The numbers of antenna element calculated for each type of floor are placed in each floor. The active Das for low and high level demand is shown in diagram 6.1 and 6.2. The placement of main unit, expansion unit is same as well for high level demands but only variation in the remote units and number of antenna elements for the floor. The length of cables is now calculated after placing the elements. The length of fiber optic cable is same in high and low level demand. The cable lengths for low and high level demand are shown in table 6.5.
Table 6.5 Length of cables for low and high level demand
Floor Type
No. of Floors
Number of antenna elements
Number of Remote Units
Number of Main Units
Number of Expansion
Unit Low level Demand
High level
Demand
Low level
Demand
High level
Demand
Type 1 1 2 3 2 3 1
4 Type 2 3 2 4 2 4
Type 3 4 3 5 3 5
Total 20 35 20 35
Cable Type Low level Demand High level Demand
Fiber Optic (single mode)
140 m 140 m
Thin Coaxial (0,5 inch)
200 m 350 m
TV Coaxial (RG-6)
1120 m 1694 m
44
Diagram 6.1 Active DAS network for low level demand
45
Diagram 6.2 Active DAS for high level demand
46
47
Chapter 7
7 Cost Results
In this chapter cost results obtained from cost models are represented. This chapter covers CAPEX, OPEX and NPV results. The analysis of different indoor solutions is based on cost and performance. Better coverage and capacity is the requirements for users and with the low CAPEX and OPEX cost. In order to fully compare Femtocell, Picocell, WLAN and DAS both CAPEX and OPEX is to consider in analysis. In table 9 the resulting CAPEX, OPEX and Net Present Value (NPV) for all indoor solutions for different values of spectral efficiency with low and high level demand is shown. The NPV analysis is done for 5 years, assuming all investments are made year 1 and discount rate is considered 5%. It is assumed that the OPEX is increasing 10% each year. In this thesis the CAPEX, OPEX and NPV for Femtocell, Picocell, WLAN and active DAS are calculated for UMTS, HSDPA, LTE and 802.11n with low and high level demand. The result of each indoor solution is shown in 7.1, 7.2, 7.3 and 7.4.
Femtocell
Radio Access
Technology
SE
(bps/Hz)
Low Level Demand High Level Demand
CAPEX (k€)
OPEX (k€)
NPV (k€) CAPEX (k€)
OPEX (k€)
NPV (k€)
UMTS
0.3
30.1
3.612
47.58
45.15
5.418
71.38
HSDPA
2
30.1
3.612
47.58
30.1
3.612
47.58
LTE
4
30.1
3.612
47.58
30.1
3.612
47.58
Table 7.1 CAPEX, OPEX and NPV for Femtocell
Picocell
Radio Access
Technology
SE
(bps/Hz)
Low Level Demand High Level Demand
CAPEX (k€)
OPEX (k€)
NPV (k€) CAPEX (k€)
OPEX (k€)
NPV (k€)
UMTS
0.3
32.7
9
87.65
327
90
876.46
HSDPA
2
21.8
6
58.43
54.5
15
146.08
LTE
4
21.8
6
58.43
21.8
6
58.43
Table 7.2 CAPEX, OPEX and NPV for Picocell
48
Active DAS
Radio Access
Technology
SE
(bps/Hz)
Low Level Demand High Level Demand
CAPEX (k€)
OPEX (k€)
NPV (k€) CAPEX (k€)
OPEX (k€)
NPV (k€)
UMTS
0.3
71.35
13.2
137.09
327.1
40.2
522.07
HSDPA
2
53.348
11.2
109.47
102.06
15.2
176.81
LTE
4
53.348
11.2
109.47
66.058
11.2
120.62
Table 7.3 CAPEX,OPEX and NPV for Active DAS
WLAN
Radio Access
Technology
SE
(bps/Hz)
Low Level Demand High Level Demand
CAPEX (k€)
OPEX (k€)
NPV (k€) CAPEX (k€)
OPEX (k€)
NPV (k€)
802.11n
1
108
50.76
368.71
108
50.76
368.71
Table 7.4 CAPEX, OPEX and NPV for WLAN
For analyzing and comparison purposes NPV is taken into account which contains both CAPEX and OPEX. The NPV for all indoor solutions are shown individually and all solutions are compared together for low and high level demand shown in Figure 7.1-7.6.
Diagram 7.1 NPV for active DAS for low and high level demand
0
100
200
300
400
500
600
0,3 2 4
NP
V (
k€)
Spectral Efficiency (bps/Hz)
Active DAS
low
high
49
Diagram 7.2 NPV for Picocell for low and high level demand
Diagram 7.3 NPV for Femtocell for low and high level demands
Diagram 7.4 NPV for WLAN for low and high level demands
0
200
400
600
800
1000
0,3 2 4
NP
V (
k€)
Spectral Efficiency (bps/Hz)
Picocell
low
high
0
20
40
60
80
0,3 2 4
NP
V (
k€)
Spectral Efficieny (bps/Hz)
Femtocell
low
high
0
100
200
300
400
SE = 1
NP
V (
k€)
Spectral Efficiency (bps/Hz)
WLAN
low
high
50
Diagram 7.5 NPV for DAS, Picocell and Femtocell for all low level demand
Diagram 7.6 NPV for DAS, Picocell and Femtocell for high level demand
0
20
40
60
80
100
120
140
160
0,3 2 4
NP
V (
k€)
Spectral Efficiency (bps/Hz)
Low Level Demand
DAS
Picocell
Femtocell
0
100
200
300
400
500
600
700
800
900
1000
0,3 2 4
NP
V (
k€)
Spectral Efficiency (bps/Hz)
High Level Demand
DAS
Picocell
Femtocell
51
Chapter 8
8 Conclusion and Future Work
8.1 Conclusion
This thesis was based on techno-economic analysis for different wireless indoor solutions. The theme is to explore which indoor solution is cost optimal among all of them for certain scenario. Different types of environment in a building for coverage and levels of demands are considered to estimate the technical and economical performance of Femtocell, Picocell, WLAN and active DAS. In introduction part of this thesis research question are introduced regarding indoor solutions. This section covers the answers for research questions after estimation from results. Before answering the research questions some important findings about each indoor solution need to be look. The following points are drawn about each indoor solution after analyzing the results which are follows: DAS
- The spectral efficiency impacts the cost distribution i.e. increase in spectral efficiency tends to decrease the network cost.
- The cost distribution is different for low and high level. The network cost varies
if demand is vary. For low demand cost is less and for high demand cost goes high.
Picocell - For low demand scenarios the increase in spectral efficiency does not impact
too much, the cost distribution is almost same.
- In high demand scenarios the cost distribution gradually decreases with the increase in spectral efficiency
Femtocell
- Femtocell introduces more flexibility in the network in terms of handling traffic demand. The increase in demand does not impact the cost distribution severely. Overall the cost distribution is almost same in low and high level demands.
- The cost distribution is almost same for different levels of spectral efficiency
and the use of radio access technology.
52
WLAN - The cost distribution is same for low and high low level demands and suitable
for long term solution. All indoor solutions are needed to compare for estimating the results. Below are the answers of research questions obtained from analysis and results.
- Will Femtocell be cost economical and stable system than WLAN (no frequent modifications required)?
Yes, Femtocell is an economical solution when comparing with WLAN.
Femtocell is suitable for long term solution capable of handling variations of traffic demand. Moreover it is also concluded that NPV of Femtocell among other indoor solutions.
- Will the cost distribution of Femtocell and WLAN be same if variation occurs in
traffic demand? Yes, cost distribution of Femtocell and WLAN is almost same. For the case of WLAN cost distribution is similar for low and high demand scenario. Femtocell cost distribution is almost same but it is vary when spectral efficiency is below 1 bps/Hz.
- Which indoor solution’s cost distribution varies when different RATs are used? DAS and Picocells cost distribution impacts greatly with variations in spectral efficiency especially for high demand scenarios. DAS and Picocell are specialized for coverage prospective but for demand they are not good flexible.
- Will increment in traffic demand affects DAS and Picocell’s cost distribution? Yes, the cost distribution for DAS and Picocell affected by the traffic demand. The increase in traffic demand tends these indoor solutions to higher NPV. For demand flexibility these systems are not suitable to handle traffic variations.
Finally, the analysis of this thesis estimates behavior of each indoor solution with different inputs, building floor types (different attenuations) for coverage, radio access technologies with multiple levels of spectral efficiency. The analysis provides guidelines for selecting appropriate indoor solutions during planning process according to the required scenarios.
53
8.2 Future Work
- Practical measurements will helpful for better estimation of coverage as compare to theoretical estimations.
- The techno-economic analysis is required to done for different types and size
of buildings or scenarios; it will provide more strength to estimated results.
- Information sharing among base stations in wireless indoor network will help load balancing and will make it efficient network.
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55
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