1. Cellular Networks: Architectural and Functional Overview, Evolving Trends, and Clean Slate Design Paradigms

2. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

3. Cells Different Frequencies or Codes
Basics: Structure
Multiple Access
Downlink
Handoff
Uplink
Mobile Station Distributed transceivers
Base Station Fixed transceiver
Cells Different Frequencies or Codes

4. Basics: Multiple Access Methods
Frequency
TDMA: Time Division Multiple Access
CMDA: Code Division Multiple Access
FDMA: Frequency Division Multiple Access
Codes
Time

5. Some More Basics Uplink & Downlink separated in
Time: Time Division Duplex (TDD), or
Frequency: Frequency Division Duplex (FDD)
Information (voice, data) is digitized and bit streams 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)

6. Cellular Technology Evolution
0G: Mobile radio telephones (PTT, MTS)
1G: Analog
2G/3G and beyond - digital:
GSM Family
cdmaOne/CDMA2000 Family
GSM
cdmaOne/IS-95
GPRS 2G
EDGE
HSCSD
WCDMA (UMTS) 3G
CDMA2000 EV-DO
HSPA

7. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

8. Global System for Mobile communications (GSM)
900/1800 MHz band (US: 850/1900 MHz)
For 900 MHz band
Uplink:
Downlink:
25 MHz bandwidth carrier frequency channels, 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.

9. Architecture

10. The Base Station Subsystem (BSS)
Base Transceiver Station BTS - transceivers serve different frequencies.
Frequency hopping by handsets and transceivers
Sectorization using directional antennas
Base Station Controller (BSC) controls several (tens to hundreds) of BTSs
allocation 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

11. Network Switching Subsystem (NSS)
GSM circuit-switched core network manages communication between mobile phones & PSTN
Mobile Switching Center (MSC) : provides circuit switched calling, mobility management, GSM services for users
Gateway MSC – interfaces with PSTN, determines which visited MSC the subscriber being called is currently located at
Visited MSC - MSC where a customer is currently located. The Visitor Location Register (VLR) associated with this MSC has subscriber's data.
Anchor MSC - MSC from which handover initiated.
Target MSC - MSC toward which a handover should take place.

12. GPRS core network
Mobility management, session management, and transport for IP services
GPRS Tunneling Protocol, GTP (over UDP) allows end users mobility with continued Internet connectivity
GPRS support nodes (GSN)
GGSN - Gateway GPRS Support Node
SGSN - Serving GPRS Support Node

13. GSM Support for Data Services: GPRS
User gets pair of uplink and downlink frequencies.
Multiple users share the same frequency channel with time domain multiplexing.
Packets have constant length corresponding to a GSM time slot.
Downlink uses FCFS packet scheduling
Uplink
Slotted ALOHA for reservation inquiries during contention phase
data transferred using dynamic TDMA with FCFS scheduling.
Upto 64 kbps (more for EDGE) downlink per user.

14. UMTS and 3G technologies (WCDMA & HSPA)
Universal Mobile Telecommunications System (UMTS) - WCDMA as the underlying interface
Supports up to 14 Mbps rates with HSDPA (typical present deployed rates per user 384kbps)
Frequency bands
Mhz (uplink), Mhz (downlink)
US: MHz and 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 ( , 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 the Internet, ISDN, GSM or UMTS.
Using PCMCIA or USB card, or cellular router customers are able to access 3G broadband services

15. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

16. In the decade beyond 2010
Next Generation Mobile Networks (NGMN) Ltd. - Consortium with partnership of major mobile operators
Recommendations without specific technology prescriptions
Target to establish performance targets, recommendations and deployment scenarios for future wide-area mobile broadband network packet switched core
The architecture intended to provide a smooth migration of existing 2G/3G networks towards an IP network that is cost competitive and has broadband performance.

17. NGMN: Beyond 3G
Video telephony and multimedia conferencing, IM, video streaming – 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 Mbps
Peak > 100Mbps downlink
Latency core < 10ms, RAN <10ms, <30ms e2e
QoS based global roaming
Broadcast, multicast, and unicast services to subscribers of all environments
Real time, conversational and streaming in PS across all required bearers
Cost per MB : as close to DSL as possible

18. NGMN Envisioned System Architecture

19. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

20. Alternative fixed wireless and MAN standards
WiMAX, the Worldwide Interoperability for Microwave Access based on IEEE standard
Last-mile broadband access, backhaul for cellular networks, interconnectivity for hotspots
OFDMA used by e. MIMO support amongst recent developments
Licensed spectrum profiles: 2.3GHz, 2.5GHz and 3.5GHz. US mostly around 2.5 GHz, assigned primarily to Sprint Nextel, Clearwire.
Claims for delivery of 70 Mbps, and over 50 kilometers, not simultaneously true.

21. 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

22. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

23. Cellular Networks and Internet
Incipient Service
Data
Voice
Circuit Switched Analog
Circuit Switched Digital
C.S. Voice + P.S. Data
Packet Switched
Technology
Evolution
Controlled
Semi-Organic
Operator initiated or partnered
Third party/ independent (largely)
New Services
Mobility Support
Good
Poor

24. Cellular Networks and Internet
QoS at edges
Good Support (voice vs. data)
Mostly absent
Data rates for supporting broadband services
Insufficient as of present
Relatively high
Cost per MB of data
Lower
Higher

25. Internet : Sample scenario – Residential Broadband access
BRAS
DSLAM
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?

26. Cellular Scenario Better QoS, scheduling
Better Mobility within the cellular network
Integrated voice/data Authentication
Downside is excessive edge network delays, costs of network deployment.

27. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

28. The Economics 3G spectrum licensing and migration cost
Telecom equipment vendors – economics of 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.

29. Agenda Basics & Technology Evolution
Architecture and Functionality (GSM, 3G and beyond)
Cellular future goals (2010 and beyond)
Emerging trends
Alternative wireless access technologies
Convergence
Comparison with Internet and sample scenario studies
Economics of operation
From a clean slate

30. From a Clean Slate
Greater intelligence at edges of networks, eventually leading to just network elements of different sizes and capabilities
Functional homogeneity in network elements in terms of storage/caching, processing, networking capability. Such network element 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.

31. Options for operators Sharing the spectrum/infrastructure costs?
New service models to forestall cost of upgrades
Good opportunity for fixed and mobile carriers to take initiative.

32. 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 (Mobicom’07, extended abstract)
Heterogeneous Network access
Optimal Control theoretic approach for rate allocation (WiOpt’07)
Convex optimization framework for media-aware rate allocation for HD video sequences (ACM Multimedia’07, best student paper award)
Markov Decision Process based flow assignment over heterogeneous networks (IEEE WoWMoM’07, 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 Multimedia’07)

33. Publications and other information: http://www.stanford.edu/~jatinder
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