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8/8/2019 Clean Slate Stanford Singh

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Cellular Networks:Architectural and Functional Overview,

Evolving Trends, and Clean Slate DesignParadigms

Jatinder Pal SinghDeutsche Telekom Labs,

Stanford University,

Oct., 2007


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Agenda

Basics & Technology Evolution Architecture and Functionality (GSM, 3G and

beyond) Cellular future goals (2010 and beyond)

Emerging trendsAlternative wireless access technologiesConvergence

Comparison with Internet and sample scenario

studies Economics of operation From a clean slate


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Basics: Multiple Access Methods

Time

Frequency

Codes

TDMA: Time

Division Multiple

Access

FDMA: FrequencyDivision Multiple

Access

CMDA: Code

Division Multiple

Access


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Some More Basics

Uplink & Downlink separated in

Time: Time Division Duplex (TDD), or

Frequency: Frequency Division Duplex (FDD)

Information (voice, data) is digitized and bitstreams modulated onto carrier

Modulation, data redundancy (coding),transmission power, data retransmissions (ARQ)

adapted to varying wireless channel quality Spatial attenuation of signal

Frequency or codes can be reused (frequency reuse)


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Cellular Technology Evolution

0G: Mobile radio telephones (PTT, MTS)

1G: Analog

2G/3G and beyond - digital:

GSM Family cdmaOne/CDMA2000 Family

GSM

GPRS

EDGE

HSCSD

WCDMA (UMTS)

HSPA

cdmaOne/IS-95

CDMA2000 EV-DO

2G

3G


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Global System for Mobilecommunications (GSM)

900/1800 MHz band (US: 850/1900 MHz)

For 900 MHz band

Uplink: 890-915

Downlink: 935-960

25 MHz bandwidth - 124 carrier frequencychannels, spaced 200KHz apart

Time Division Multiplexing for 8 full rate speech

channels per frequency channel. Circuit Switched Data with data rate of 9.6 kbps

Handset transmission power limited to 2 W in

GSM850/900 and 1 W in GSM1800/1900.


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Architecture


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The Base Station Subsystem (BSS)

Base Transceiver Station BTS - transceivers servedifferent frequencies.

Frequency hopping by handsets and transceivers

Sectorization using directional antennas

Base Station Controller (BSC) controls several(tens to hundreds) ofBTSsallocation of radio channels

handovers between BTSs

concentrator of traffic

databases with information such as carrier frequencies,frequency hopping lists, power reduction levels, etc.for each cell site


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Network Switching Subsystem (NSS)

GSM circuit-switched core network managescommunication between mobile phones & PSTN

Mobile Switching Center (MSC) : provides circuitswitched calling, mobility management, GSM

services for usersGateway MSC interfaces with PSTN, determineswhich visited MSC the subscriber being called iscurrently located at

Visited MSC - MSC where a customer is currentlylocated. The Visitor Location Register (VLR) associatedwith this MSC has subscriber's data.

Anchor MSC - MSC from which handover initiated.Target MSC - MSC toward which a handover should

take place.


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GPRS core network

Mobility management, sessionmanagement, and transport for IP services

GPRS Tunneling Protocol, GTP (over UDP)

allows end users mobility with continuedInternet connectivity

GPRS support nodes (GSN)

GGSN - Gateway GPRS Support NodeSGSN - Serving GPRS Support Node


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UMTS and 3G technologies(WCDMA & HSPA)

Universal Mobile Telecommunications System (UMTS) - WCDMA asthe underlying interface

Supports up to 14 Mbps rates with HSDPA (typical present deployedrates per user 384kbps)

Frequency bands 1885-2025 Mhz (uplink), 2110-2200 Mhz (downlink)

US: 1710-1755 MHz and 2110-2155 MHz W-CDMA has 5 Mhz wide radio channels (CDMA2000 transmits on

one or several pairs of 1.25 Mhz radio channels). HSDPA allows networks based on UMTS to have higher data rates

(1.8. 3.6, 7.2, 14.4 Mbps via AMC, and HARQ, fast packet scheduling. UMTS air interface forms Generic Radio Access Network (GeRAN)

which can be connected to various backbone networks like theInternet, ISDN, GSM or UMTS. Using PCMCIA or USB card, or cellular router customers are able to

access 3G broadband services


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Agenda







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In the decade beyond 2010

Next Generation Mobile Networks (NGMN) Ltd. -Consortium with partnership of major mobileoperators

Recommendations without specific technology

prescriptions Target to establish performance targets,recommendations and deployment scenarios forfuture wide-area mobile broadband networkpacket switched core

The architecture intended to provide a smoothmigration of existing 2G/3G networks towards anIP network that is cost competitive and hasbroadband performance.


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NGMN: Beyond 3G

Video telephony and multimedia conferencing, IM, videostreaming among high drivers for NGMN

Essential System recommendations Seamless mobility across all bearers with service continuity

through a min of 120 km/h

Peak uplink data rates 30-50 Mbps Peak > 100Mbps downlink

Latency core < 10ms, RAN


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NGMN Envisioned SystemArchitecture


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Agenda







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Alternative fixed wireless and MANstandards

WiMAX, the Worldwide Interoperability forMicrowave Access based on IEEE 802.16standard

Last-mile broadband access, backhaul for cellular

networks, interconnectivity for hotspots OFDMA used by 802.16e. MIMO support amongst

recent developments

Licensed spectrum profiles: 2.3GHz, 2.5GHz and

3.5GHz. US mostly around 2.5 GHz, assignedprimarily to Sprint Nextel, Clearwire.

Claims for delivery of 70 Mbps, and over 50kilometers, not simultaneously true.


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Convergence

Heterogeneous access technologies

Multi-mode access devices

Dual mode phones (WiFi, 2.5/3G), UMA

Heterogeneous Services Cellular Internet access and Internet based

voice/video access

Challenges

Time variant heterogeneous network characteristics

Heterogeneous applications with different utilities

System design and networking challenges


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Agenda




Comparison with Internet and sample

scenario studies

Economics of operation From a clean slate


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Cellular Networks and Internet

Cellular NetworksInternet

VoiceData

Packet

Switched

Controlled Semi-Organic

Good Poor

Incipient

Service

Technology

Evolution

Mobility

Support

Circuit Switched Analog

Circuit Switched Digital

C.S. Voice + P.S. Data

New ServicesOperator initiated

or partneredThird party/

independent (largely)


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Cellular Networks and Internet

Cellular Networks Internet

Data rates for

supporting

broadband

services

Insufficient as of

presentRelatively high

Cost per MB

of dataHigher

Lower

QoS at edges Good Support

(voice vs. data)Mostly absent


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Internet : Sample scenario Residential Broadband access

Internet

BRASDSLAM

Home WiFi Router

QoS: Wireless hop (802.11e?), PPPoE, IP QoS (Diffserv)

and translation mechanisms

Mobility Options: MIP - high-barrier, delay performance,

incremental patch rather than clean solution?


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Agenda







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The Economics

3G spectrum licensing and migration cost

Telecom equipment vendors economicsof operation, meeting bids vs. system

upgrades for technical innovation Stiff competition for fixed and mobile

segments of operators, drive towards

services. Interesting and sometimes conflicting

dynamics for both fixed and mobile

operators.


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Agenda







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From a Clean Slate

Greater intelligence at edges of networks, eventually leading to justnetwork elements of different sizes and capabilities Functional homogeneity in network elements in terms of

storage/caching, processing, networking capability. Such networkelement should likely be multi-homed connected with heterogeneous technologies (including

p2p, delay tolerant), have intelligence for resource allocation, QoS have interaction capability with other network elements (including user

devices), support mobility, handoffs have ability to recognize needs of existing and new applications (HDTV,

phone, streaming video)

be plug and play Interfacing of applications/services (QoS specs) with underlying

serving networks for fast and easy deployment. Heterogeneity in access technologies amongst user carried devices

honored and accepted by the network elements.


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Options for operators

Sharing the spectrum/infrastructure costs?

New service models to forestall cost ofupgrades

Good opportunity for fixed and mobilecarriers to take initiative.


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Deutsche Telekom Laboratories:Related Research Efforts

Broadband Access Sharing (Extended HotSpots) Commercial grade routers with virtualization, user traceability, limited

QoS support. Limited trail in Berlin; Pilot for extensive evaluation launched and

technology on company product roadmap for 2008. Distributed Authentication framework for a Global WiFi network

(Mobicom07, extended abstract)

Heterogeneous Network access Optimal Control theoretic approach for rate allocation (WiOpt07) Convex optimization framework for media-aware rate allocation for HD

video sequences (ACM Multimedia07, best student paper award) Markov Decision Process based flow assignment over heterogeneous

networks (IEEE WoWMoM07, top 15 papers)

Peer to Peer Media Streaming Large scale dynamics of a commercial P2P streaming session and real-

world testing of commercial P2P streaming solutions. Gossip based P2P streaming protocol (Journal on Advances in

Multimedia07)


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Publications and other information:

http://www.stanford.edu/~jatinder

Email:

[email protected]

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