Third Generation (3G) Mobile Services

Ref.: 1.Chap. 5: Wireless Networks By P. Nicopolitidis, M.S. Obaidat, et al, Ed.20032. Chap.4: Mobile communications, By J.Shiller, II Ed. 20033. Chap.4,6,7,8: 3G wireless networks, By C.Smith, D.Collins, II Ed. 2007

Data rate

1Gb/s

GPRS, GSMWiMAXWi-Fi

BluetoothRFID

Wireless Network Classification

Wireless Evolution 1990-2010

WWAN WLAN

WMAN

USA

Europe Japan

China

USA

*ITU redefined in Dec.,2010 that LTE, HSPA+, Mobile WiMAX referred as 4G

*4G

5G

Peak Data Rate

• Introduction• 3G• IMT-2000:* CDMA-2000• UMTS:* WCDMA* TD-CDMA* TD-SCDMA• QoS• 3.5G

Third Generation (3G) System

• Objective is to provide fairly high speed wireless communication to support data and video in addition to voice

• Person should be able to talk to any one else in the world with a PSTN quality (Global Roaming)

• Persons can download and watch a movie• Can download & listen to music, surf Internet, or

play games (Multimedia services)• Can have video-conference• Portable devices always-connected to Internet.

One need not to dial a no. to connect to the Internet

• 3G concept started in 1992 by ITU called Internet Mobile Telecommunication in a year 2000 (IMT-2000)

• IMT- 2000 named because * 3G system available in 2000, * operates at 2000MHz frequency, * with data rate of 2000kb/s

• Data rate of * 144kb/s for access in a moving car,* 384kb/s for access as the user walks (Pedestrians) * 2Mb/s for the stationary user (office or home)

• Supports both packet-switched & circuit-switched data services

• Five alternatives for smooth evaluation from 2G systems

• 1. ETSI (European Telecom Standard Institute) developed a UMTS (Universal Mobile Telecom System) includes Wideband-CDMA (W-CDMA) with 5MHz BW

• 2. Other European UMTS is known as IMT-TC or TD-CDMA. This approach is a combination of W-CDMA & TDMA technology, intend to provide upgrade path of GSM system (IMT-2000)

IMT-2000 Terrestrial Radio Interfaces

1 23 4 5

• 3. CDMA-2000 is USA origin, uses multi-carrier (MC-CDMA) with narrowband 1.25MHz BW like CDMA (IS-95)

• 4. IMT-SC single carrier designed for TDMA only network (TDD)

• 5. IMT-FT frequency time uses FDMA & TDMA. It is out growth of DECT (Digital Enhanced Cordless Telecom) standard

• 3GPP:

• 3GPP (3G Partnership project) standardized GSM based system (W-CDMA)

• 3GPP2 standardized CDMA based system (CDMA2000)

• Nokia & Ericsson backed W-CDMA • while US vendors including Qualcom & Lucent

backed CDMA-2000

• The frequency for IMT-2000 allocated were • 1885-2025MHz and • 2110-2200MHz.

• IMT-2000 was operational in 2002 at Japan, Norway, Finland, Sweden, Korea, USA

Radio Transmission Technology

16

IS-95 IS-136 & PDCGSM-

EDGE

GPRS

HSCSDIS-95B

Cdma2000-1xRTT

Cdma2000-1xEV,DV,DO

Cdma2000-3xRTT

W-CDMA

EDGE

TD-SCDMA

2G

3G

2.5G

3GPP3GPP2

• CDMA-2000

• In 2G system IS-95 known as CDMAone is based on CDMA technology. 3G CDMA base systems will require software and minor hardware changes to the existing CDMAone

• USA offers 3G services by deploying an overlay of CDMA2000 and IS-95 in the same spectrum

• CDMA2000 is a Multi carrier (MC)-CDMA in which single 5MHz band can accommodate 3 adjacent carriers (3X1.25) with guard bands both sides

CDMA2000

WCDMA

3G CDMA

• 1X uses 1.25MHz carrier while 3X will use 3.75MHz (3X 1.25MHz)

• The 6X, 9X and 12 X mode will be standardized in future

• 1X doubles the voice quality of CDMAone and provides data rate of 144kb/s by using 128 Walsh code instead of 64.

• 3X uses 256 Walsh code for higher data rate

• This performance is obtained by enhancement of CDMA2000 PHY and MAC layer

• For High data rate (HDR) 16-QAM (Quadrature Amplitude Modulation) is used instead of QPSK, thus offering 621 kb/s data rate

• In case of large interferences 8-PSK or QPSK is used which is more robust than 16-QAM but reduces the data rate

• 3X also known as IS-2000-A is an enhancement of 1X and uses 3 CDMAone carriers for a total BW of 3.75MHz (3X1.25) and chip rate of 3.6864Mcps (3X1.2288).

• It can support data rates up to 2Mb/s

• CDMA2000 upgrades CDMAone by modifying BTS with ‘multimode channel elements cards’, BSC with ‘IP routing capabilities’ and introducing the Packet data server network (PDSN) Fig.

• PDSN is essential element in the treatment of packet data services

• Purpose of PDSN is to support packet data services

• PDSN performs following functions:* Establishes, maintains, and terminates Point-to-

Point protocol (PPP) sessions with the subscriber* Establishes, maintains, and terminates the logical

links to the radio network* Initiates Authentication, Authorization, and

Accounting (AAA) for the mobile client from the AAA server

* Routes packets to- and from the external packet data networks (PDN)

• The overall capacity of PDSN is determined by both throughput and no. of PPP (Point-to-Point) sessions that are being served

• AAA server provides Authentication, Authorization, and Accounting functions for the packet data network associated with CDMA 2000

• The PDSN provide several key packet-data services, including simple IP, and Mobile IP

• Simple IP is a packet-data service relative to CDMA2000 1X. Subs is assigned a Dynamic host configuration protocol (DHCP) address from the serving PDSN with its routing service provided by the local network

• The specific IP address that the subs is assigned retains with the subs as long as it is served by the same radio network that maintains connectivity with the PDSN that issued the IP address

• It is important to note that simple IP does not provide for mobile termination and hence is an origination-based service only ie a PPP service using the DHCP

• Simple IP is similar to the dial-up Internet connections used by many people over standard landline facilities

• A PPP session is established between the mobile unit (MS) and the PDSN. The PDSN routes packets to- and from the MS in order to provide end-to-end connectivity between the MS and the Internet and the PDSN. Fig. presents a diagram depicting Simple IP

• During Simple IP, MS must be connected to the same PDSN for the duration of the packet session. If the MS moves to another PDSN, the Simple IP connection is lost and needs to be reestablished. MS must negotiate for a new IP address from the new PDSN

BSC PDSN Internet ServerMS BTS

PPP

IP

Simple IP

• To explain Simple IP process, a call flow or packet-session flow chart is given in Fig.

• The VLR is normally collocated with the MSC. When a subs initiates a packet-data session, the BSC via the MSC/VLR checks the subs subscription prior to the system granting the service request to the mobile subs. This will take place prior to the PDSN being involved with the packet session

• In Mobile IP, the mobile unit (MS) is assigned a static IP address that resides with the HA. It can handoff between different radio networks that are served via different PDSNs, which resolves the roaming issues

MS BTS/BSC MSC/VLR VLR PDSN AAA

Simple IP Flow chart

Access Procedure

ValidationMS

MS Validated

Start PPP Authentication RequestAuthentication response

PPP Established

PacketSession

EndSession

End Packet Session

AAA A/C Start

AAA A/C Stop

• Mobile IP allows the mobile node to use two addresses. These IP addresses are called home address and care-of address. The home address is static and is known to everybody as the identity of the host. The care of address changes at each new point of attachment and can be thought of as mobile node’s location specific address

• The network node that is responsible for forwarding and managing this transparency is known as the home agent

• Whenever the mobile node moves, it registers its new care-of address (provided by Foreign agent) with its home agent. The home agent forwards the packet to the foreign network using the care-of address.

• The home agent encapsulates the original IP datagram into a new IP datagram with care-of address in the header and retransmit the datagram. This phenomenon is called tunneling

• Let us consider an example of IP datagram being exchanged over a TCP connection between mobile node A and server X

• Server X wants to transmit an IP datagram to node A. The home address of A is advertised and is known to X. X sends packet to A with A’s home address as the destination IP address in the IP header (1)

• At the A‘s home network, the incoming IP datagram is intercepted by the home Agent. Home agent finds that A is in a foreign network

• Care-of address has been allocated to mobile node A by a foreign network and is available with the home agent. The home agent encapsulate the entire datagram with a care-of address in the IP header. The new IP datagram with the care-of address as the destination address is retransmitted by home agent (2)

• At the foreign network, the new IP datagram is intercepted by the foreign agent. The foreign agent is counterpart of the home agent in the foreign network. The foreign agent strips off the care-of address and delivers the original datagram to A(3)

• A tends to respond to this message and sends packet to X. Here X is not mobile hence has a fixed IP address. A sends IP datagram to a router on the foreign network for routing to X (4). Typically this router is the foreign agent. A uses X’s IP static address as the destination address (5)

CDMA2000 -1xRTT:

• One carrier CDMA2000 Radio Transmission Technology (RTT)

• 1x represents ‘1’ times the frequency BW • Modulation scheme uses BPSK & QPSK• The peak data rate for DL is 621kb/s and

153.6kb/s for UL• The average data rate across cell area varies from

60 to 100kb/s depending on distance of the MS from BS

CDMA2000 1xEVDO: • Single RF carrier Evolution (to 3G) to Data Only• The channel BW is 1.25MHz with chip rate

1.2288Mc/s• Improved code rates & higher order modulation

(BPSK to 16-QAM) for large packets provide high spectral efficiency (b/s/Hz)

• The DL peak data rate is 2.4Mb/s and UL peak data rate is 153.6kb/s

• MS performs channel quality measurement and reports the index out of 12 configuration which in turn transmits requested configuration

CDMA2000 1xEVDV: • Single RF carrier Evolution to Data and Voice• The BW, chip rate, modulation techniques are

same as that of 1xEVDO• EVDV integrates voice & data on the same carrier

and uses soft handoff for voice & cell selection for data

• The peak data rate in DL is 3.1Mb/s and 1.8Mb/s in UL both higher than EVDO

• Modulation & coding chosen from one of the 504 available configuration for each transmission based on the amount of data to be transmitted and channel condition

IS-95B

IS-95BUses multiple code channelsData rates up to 64kbpsMany operators gone direct to 1xRTT

CDMAIS-95AIS-95A14.4 kbpsCore network re-used inCDMA2000

1xRTTCDMA2000 1xRTT: single carrier RTTFirst phase in CDMA2000 evolutionEasy co-existence with IS-95A air interfaceRelease 0 - max 144 kbpsRelease A – max 384 kbpsSame core network as IS-95

1xEV-DO

CDMA2000 1xEV-DO: Evolved Data Optimised Third phase in CDMA2000 evolutionStandardised version of Qualcomm High Data Rate (HDR)Adds TDMA components beneath code componentsGood for highly asymmetric high speed data appsSpeeds to 2Mbps +, classed as a “3G” systemUse new or existing spectrum

1xEV-DV CDMA20003xRTT

CDMA2000 1x Evolved DVFourth phase in CDMA2000 evolutionStill under developmentSpeeds to 5Mbps+ (more than 3xRTT!)Possible end game.

CDMA2000 evolution to 3G

3.9/4G

3.5G

GSM Family

UMTS:

5G

UMTS (Universal Mobile Telecom System)• UMTS is European standard of IMT2000,

introduced WCDMA (Wideband CDMA)• WCDMA: • uses CDMA instead of TDMA in GSM• Wideband CDMA uses Direct Sequence (DS)-

CDMA and has a Wideband of 5MHz. The chip rate is 3.84Mcps

• Supports peak data rate of 2Mb/s using QPSK modulation in both DL and UL

• WCDMA require new spectrum allocation and new, or upgraded GSM mobile phones

• This wider BW has benefits such as higher data rates and improved multi-path resolution. The average data rates supported up to 2Mb/s

• UMTS is cost effective migration from GSM• Fig. Shows basic ideas of spreading and

separation of different senders in UMTS• User data is spread using orthogonal spreading

codes (user based)• After spreading all chip streams are added and

scrambled. In FDD mode, scrambling code is unique for each sender and separates all senders

• For TDD the scrambling code is cell specific ie all stations in a cell use the same scrambling code and cells are separated using different unique scrambling code (cell based)

• The scrambled chips are QPSK modulated and transmitted

User 1 User 2

User Data Spreading

• In WCDMA, orthogonal spreading codes reduces interference and scrambling is used to separate the users/cells in downlink

• In uplink, low cross-correlation codes (orthogonal codes) are used to separate the mobiles

• The WCDMA code is same as IS-95 with a spread factor of 4 to 512. Higher data rates are obtained by using shorter spreading codes since 3.84Mcps chip rate is held constant.

• GSM/GPRS/EDGE network is upgraded to support WCDMA. WCDMA architecture is split into access network and core network

• WCDMA architecture consists of Radio network controller (RNC) and B nodes. RNC is analogous to the GSM base station (BSC). RNC responsible for control of the radio resources within the network. B node is similar to BTS

• The interface between RNC and the B nodes is Iub interface like the Abis in GSM. Together an RNC and the B nodes is called Radio network subsytem (RNS) like BSS in GSM

• RNC is connected with core network over interface Iu (like A interface in GSM). The interface between RNC and SGSN is through IuPS (supports packet switched circuit) like Gb in GPRS. The interface between RNC and MSC is via IuCS (circuit switched)

Circuit switched (GSM)

Packet switched

Core Network

WCDMA

Access Network

• Both domains need the databases EIR & HLR for location management

• Reusing the existing infrastructure helps to save a lot of money and may convince to use WCDMA if they are already using GSM

• Fig. Shows protocols stacks of Circuit switched domain (CSD) and Packet switched domain (PSD)

• The CSD used ATM (Asynchronous Transfer Mode) Adaptation Layer (AAL2) for voice

• Segment and Reassemble layer (SAR) used to segment data packets received from the RLC (Radio Link Control) which can be transported in ATM

Packet data coverage protocol

RNC

BSC

• ATM is chosen since it can transport and multiplex low bit rate voice data with low jitter and latency (Compared to protocols used in PSD)

• In PSD ATM with AAL5, UDP/IP is used (Data)• All packets (IP, PPP) destined for UE are

encapsulated using the GPRS tunneling protocol (GTP)

• In UMTS the RNC handles the tunneling protocol GTP, while in GSM/GPRS GTP is used between a SGSN and GGSN only

• RNC performs protocol conversion from the combination GTP/UDP/IP into the Packet data convergence protocol (PDCP)

• TD-CDMA:

• TD-CDMA differs from W-CDMA and CDMA2000. It is a Time Division Duplex (TDD) instead of FDD

• TDD does not need paired frequencies. It uses the same frequency for up- and downlink transmission

• TDD is suitable for asymmetric up- and downlink transmission rates for IP data services

• There are no. of time slots, and no. of orthogonal codes in each time slot

• There are 15 time-slots between up and downlink with a frame duration of 10ms. The chipping rate is 3.84Mcps. 12 time-slots allotted for traffic and 3 for signaling. Each time-slot uses 16 unique spreading codes, one for each user or segment of BW shown in Fig.

• The first two time slot of every frame is assigned to downlink traffic. The uplink common signaling channels are in the last slot of the frame. The remaining slots are assigned on an as- needed basis for uplink and downlink usage

• TD-CDMA can assign different modulation and coding scheme for each time-slot to maximize the throughput for each subs in the sector (Adaptive modulation & coding)

1 2 3 ----- 15 16 16 spreading code

TD-CDMA

Midample for training & channel estimation

• A time-slot can support 500kb/s in a 5MHz channel. Using 10MHz channel time-slot can support 1Mb/s

• A single TD-CDMA channel is able to support 5.5Mb/s in down link and 850kb/s in uplink. Using 2 adjacent channels (10MHz) data rate is increased to 11Mb/s in the downlink and 1Mb/s in the uplink

• The coverage radius of TD-CDMA is decided by two factors: Tx power, reception sensitivity and the length of the guard period. The maximum coverage radius is about 29kms but typically 7.5kms. When large coverage areas are needed for rural applications, capacity must be reduced to achieve greater coverage.

• TD-CDMA Parameters:• Carrier BW: 5MHz• Duplex Type: TDD• Multiple Access: TDMA, CDMA• Chip rate: 3.84Mc/s• Modulation: QPSK, 16-QAM• Maximum Cell Range: 29Kms (7.5Kms nominal)• Theoretical max. data rate/user: 2Mb/s• System Asymmetry (DL:UL): 1:14-14:1• Frequency reuse: 1

• Implementation:• If the TD-CDMA is new network with no legacy

issues, then configuration(1) is shown in Fig.• Deployment of TD-CDMA into existing GSM

network where voice is through GSM and new data service through TD-CDMA. Spectrum allocation for TD-CDMA and GSM(1&3) is shown in Fig.

• Overlay of TD-CDMA on to a WCDMA network (1&2) is shown in Fig. The possible spectrum allocation is also shown in Fig.

• A spectrum allocation where TD-CDMA is deployed in an existing GSM and WCDMA network (1,2&3) is shown in Fig.

BSC

RNC

Core Network

GSM

WCDMA

TD-CDMA

TD-CDMA with WCDMA and GSM

3

2

1

GSM(3) GSM(3)

GSM(3) TD- CDMA(1)

GSM(3) TD- CDMA(1)

WCDMA(2) TD- CDMA(1)

WCDMA(2) TD- CDMA(1)

Transmitter Receiver

GSM WCDMA TD-CDMA (3) (2) (1)

GSM WCDMA TD-CDMA (3) (2) (1)

15MHz 15MHz

10MHz 5MHz10MHz 5MHz

10MHz 5MHz 10MHz 5MHz

5 5 5MHz 5 5 5MHz

Spectrum Allocation:

• TD-SCDMA:

• Time Division-Synchronous CDMA is perceived as a Chinese standard

• TD-SCDMA uses TDD as the access method allowing both asynchronous and synchronous operation

• TD-SCDMA node-B employs combination of FDMA, TDMA, CDMA (Fig. Architecture)

• RAN uses asynchronous 1.6MHz of spectrum, enabling to have multiple carriers in the same BW as a WCDMA,CDMA2000 or TD-CDMA carrier

• TD-SCDMA supports circuit switched services in addition to packet (IP) services. Circuit switched rates are 12.2,64, 144, 384, and 2048kb/s. Packet data rates are 9.6, 64, 144, 384 and 2048kb/s

TD-SCDMA

• TD-SCDMA is sponsored by China, a total of 155MHz frequency BW has been allocated for TDD which indicates that 96 (1.6X96=155MHz) unique carriers are possible

• Radio resources for the uplink and downlink are allocated separately (5ms each), even though the uplink and downlink are in the same carrier

• There are total 7 time-slots for each sub-frame (Fig.)

• A total of 16 spreading codes are used with TD-SCDMA. These codes are all orthogonal to each other and like all CDMA codes are part of tree

DataField-1 1 2 ----- 16

16 spreading code

Mid-amble

DataField-2

Gp

352 144 352 16chips

864chips

TS0 TS1 ------- TS6

Uplink

5ms 5ms

Downlink

TS6 ------TS2TS0 TS1

BCHDwPTS96chips Gp

96c UpPTS160chips

TD-SCDMA Channel Allocation

• Table lists parameters for TD-SCDMA system• Fig. shows an overlay approach for a TD-SCDMA

installed in an existing GSM spectrum• It shows a spectrum allocation for TD-SCDMA

within 5MHz BW with guard bands• It also shows the spectrum allocation of GSM with

TD-SCDMA in its existing spectrum

• Comparison of TD-CDMA, WCDMA and TD-SCDMA radio access is shown in Table

• TD-SCDMA Parameters:

• Carrier BW: 1.6MHz• Duplex Type: TDD• Multiple Access: TDMA, CDMA, FDMA• Chip rate: 1.28Mc/s• Modulation: QPSK, 8-PSK• Maximum Cell Range: 40Kms• Theoretical max. data rate/user: 2Mb/s• System Asymmetry (DL:UL): 1:6-6:1• Frequency reuse: 1

BSC

RNC

Core NetworkGSM

TD-SCDMA

1 2 31.6 1.6 1.6MHz

5MHz

GSM TD-SCDMA3.2 1.6MHz

GuardBand

TD-SCDMA

• Comparison:

TD-CDMA WCDMA TD-SCDMA• Multiple Access HCR-TDD FDD LCR-TDD• Handoff Hard Soft Hard• Modulation QPSK QPSK QPSK/8-PSK• BW 5MHz 5MHz 1.6MHz• Time slot/frame 15 7 7• Chip rate 3.84Mc/s 3.84Mc/s 1.28Mc/s• Spreading factor 1,2,4,8,16 4 to 256 1,2,4,8,16• Receiver Joint detection Rake Joint detection Rake (Mobile) Rake (Mobile)

Commonality among WCDMA, CDMA2000, TD-CDMA, TD_SCDMA:

• All of the platforms use CDMA technology and requires total of either 1.25, 1.6 or 5MHz of spectrum

• WCDMA, TD-CDMA, and TD-SCDMA use a GSM 2G network as a logical starting point as does CDMA2000 with IS-95

• GSM took 10 years to become the most successful 2G mobile communication system. A similar period of time is taken by 3G system to succeed

• Quality of Service (QoS) in 3G:• The QoS classes defined for mobile network are

very different from fixed networks due to restrictions and limitations of the air interface

• Based on delay sensitivity four QoS classes have been defined for 3G traffic: i) Conversational, ii) streaming, iii) interactive, and iv) background

• i) Conversational class is defined for the most delay-sensitive applications (voice & VoIP), and the transfer delay is strictly limited

• ii) Streaming class is defined for one-way real time video/audio (VoD).

• Both conversational and streaming classes will need better channel coding and retransmission to reduce the error rate in order to meet the required QoS

• Interactive & background classes are defined for delay-insensitive services.

• iii) interactive class is used for applications such as Telenet, interactive e-mail, and web browsing.

• iv) background class is defined for activities such as FTP or the background downloading of e-mails

• Among the traffic classes, the conversational class is most delay-sensitive, and background class is most delay-insensitive

• In addition to traffic classes several QoS parameters includes maximum, minimum, and guaranteed bit rates, delivering order, maximum packet size, reliability and so on

• A major challenge for defining QoS of 3G is compatibility with QoS of existing mobile networks (GPRS) and fixed network (Internet)

• QoS mapping for circuit switched 3G and 2G (GSM) is easy. For handoff between 3G and 2G networks, only reliability, delay, and BW are meaning full parameters

• For background download of files, the 3G QoS is mapped to GPRS reliability class 2 (NACK GTP mode) and GPRS delay class 4 (best-effort)

• For Internet applications, the 3G QoS should be mapped to Internet QoS definition, and attributes for integrated services (IntServ) and differentiated services (DiffServ). The QoS parameters of these two Internet service types are controlled by the applications (ie TE)

.

• 3G Deployment:

• In Japan mobile phone subscribers reached to 111 Million and 3G penetration exceeds 88%

• In India 400 million subscribers of 3G network will reach by 2015

• This will be 30% of total mobile phone subscribers

• WCDMA based subscribers will be around 320 million and 80 million will be CDMA2000 based

[New Wireless Intelligence study-India, 2011]

3.5G (HSDPA) (High Speed Downlink Packet Access):

• An enhanced version and the next intermediate generation of 3G UMTS.

• It comprises the technologies that improve the air Interface and increase the spectral efficiency to support data rates of the order of 14 Mbps.

• 3.5G introduces many new features that will enhance the UMTS technology in future.

• 1xEV-DV already supports most of the features that will be provided in 3.5G.

• New features include: * Adaptive Modulation and Coding * Fast Scheduling: Scheduling shifted from RNC to

B node * Backward compatibility with 3G * Enhanced air interface

• Adaptive Modulation and Coding:

• For the same symbol rate, the signal power, modulation technique, information rate, and channel coding rate can be adjusted in accordance to channel interferences and QoS requirements

• FEC rate ½, 2/3, ¾, 5/6 and Digital modulation QPSK, 16-QAM, 64-QAM are dynamically adapted for every single

individual user giving rise to 6-fold spectral efficiency (b/s/Hz)

• Mobile user closer to BS (64-QAM, ¾ rate Turbo code) and closer to cell boundary (QPSK, ½ rate Turbo code)

FEC 3/4FEC 1/2

Adaptive Modulation & Coding

AMC with Range

Fourth Generation (4G)

• 4G supports voice, data, and streamed video for all users, in all locations

• It is a networks of networks that integrates seamlessly and allows people to move between different types of radio technologies in seamless way

• 4G network will depend entirely on a full IP wireless infrastructure

• In 4G the trend is towards support for even advanced data services. The vision for 4G and future systems is towards unification of various mobile and wireless networks eg wireless cellular (2G, 3G) and wireless data network (WLAN, WiMAX, etc.)

• Cellular is circuit switched means a connection establishment is to be there prior to the call, while wireless data network is packet switched

• Evaluation of wireless networks towards an integrated system will produce a common packet switched (wireless Internet) platform

• 4G involves merger of cellular and wireless technologies including integration of

*Personal area network (Bluetooth, ZigBee, UWB),

* WLAN (Wi-Fi), * WMAN (WiMAX), * Wide Area Network (Cellular), *Regional/Global Area Network (RAN) (Radio

and TV broadcasting, satellite communication)

4G key technologies are related to

* Adaptive coding and modulation, * Software defined radio (SDR), * Multiple access schemes, * Smart antennas, * Security measures

• 4G system may begin in 2010-2015 time frame • 1Gb/s data rate for stationary & 100Mb/s for moving

vehicle.

4G Key Technology

(Low density packet code)

• Software Defined Radio (SDR):• Current approach of radio is to built multi-chip

modules, multi-transceivers on die• This needs more die area, more power

consumption, may require additional antenna and matching network

• SDR is flexible to support variety of signal BWs, modulation formats, signal levels

• LNA tunable over wide BW, DSP to achieve decimation, down conversion, channel selectivity, gain/phase compensation

• SDR increases flexibility, reduces cost, decreases power consumption, and increases performance

• SDR should move its operating characteristics in real time by software commands

• Can shift center frequency, modify BW, sampling rate, change the linearity and noise figure of a transceiver channel in real time

• One programmable transceiver can replace many fixed transceiver used in current cell phones or data modems

• Reduces size, power consumption of transceiver• SDR is better in performance even against single

transceiver • Received analog RF signal is processed by re-

programmable base band Digital signal processor (DSP) using multiple antennas and amplifiers and very fast high speed ADC and DSP functions

SDR Operations

Receiver Transmitter

• MIMO-OFDM System:• Multi-input multi-output (MIMO) antennas

technology has potential to significantly improve the capacity and performance of wireless systems

• Signal from different antennas will fade independently, thus increasing frequency diversity

• It is natural to combine two powerful technologies MIMO and OFDM in the PHY layer design

• Multiple antennas can be used at the transmitter and receiver

• OFDM with MIMO increases diversity gain and enhance system capability on a time varying multi-path fading

• Adaptive antenna array locates the user, minimizes the interferences, and maximizes intended signal reception

S

/

P

ENCQAM

mappingIFFT

Add Cyclic Prefix

Add

Cyclic

Prefix

ENCQAM

mappingIFFT

Add Cyclic Prefix

Add

Cyclic

Prefix

FFT

Remove

Cyclic

Prefix

FFT

Remove

Cyclic

Prefix

Time

and

freq.

sync

Detection

and

Decoding

Block

WiMAX + Cellular

WiMAX + WLAN

• Distribution layer: Supports digital video broadcasting services at moderate speeds over relatively large cells. This layer will support coverage and mobility and will cover sparsely populated rural areas

• Cellular layer: This layer comprises 2G and 3G systems. It provides high capacity in terms of users and data rates inside densely populated areas such as cities. This layer support data rates up to 2Mb/s. Cell size will be smaller than distribution layer. This layer support full coverage and mobility

• Hotspot layer: This layer supports high data rates over short ranges like offices or buildings. It comprise WLAN system IEEE802.11

• Personal network layer: This layer comprise very short range wireless connections such as Bluetooth, ZigBee. Mobility is limited due to very short range

• Fixed layer: This will comprise the fixed access system (WiMAX)