Introduction to Cellular Networking and Rethinking Mobile ...
Transcript of Introduction to Cellular Networking and Rethinking Mobile ...
Introduction to Cellular Networking and Rethinking
Mobile Architectures
Jatinder Pal Singh EE 392I, Lecture-3
April 13th, 2010
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
Basics: Structure
Cells Different
Frequencies or Codes
Base Station Fixed transceiver
Mobile Station Distributed transceivers
Downlink
UplinkHandoff
Multiple Access
Basics: Multiple Access Methods
Time
Frequency
Codes
TDMA: Time Division Multiple Access
FDMA: Frequency Division Multiple Access
CMDA: Code Division Multiple Access
Some More Basics Uplink & Downlink separated in
Time: Time Division Duplex (TDD), orFrequency: 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 signalFrequency or codes can be reused (frequency
reuse)
Cellular Technology Evolution
0G: Mobile radio telephones (e.g. MTS) 1G: Analog 2G/3G/4G .. - digital:
GSM/3GPP Family cdmaOne/CDMA2000 Family
GSM
GPRS
EDGE
UMTS, WCDMA
HSPA
cdmaOne/IS-95
CDMA2000 EV-DO
2G
3G
4G LTE
Agenda Basics & Technology Evolution Architecture and Functionality (GSM,
3G and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
Global System for Mobile communications (GSM)
900/1800 MHz band (US: 850/1900 MHz) For 900 MHz band
Uplink: 890-915Downlink: 935-960
25 MHz bandwidth - 124 carrier frequency channels, spaced 200KHz apart
Time Division Multiplexing for 8 full rate speech channels per frequency channel.
Handset transmission power limited to 2 W in GSM850/900 and 1 W in GSM1800/1900.
Architecture
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 channelshandovers between BTSs concentrator of traffic databases with information such as carrier
frequencies, frequency hopping lists, power reduction levels, etc. for each cell site
Network Switching Subsystem (NSS)
This GSM core network manages communication amongst mobile devices & with PSTN
Mobile Switching Center (MSC) : routing of calls and GSM services for users, mobility management, handovers, Gateway MSC – interfaces with PSTN, determines the
visited MSC at which the subscriber being called is currently located
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. Home Location Register (HLR): database with all
mobile phone subscriber details
GPRS core network Mobility management, session
management, and transport for IP services
GPRS Tunneling Protocol, GTP allows end users mobility with continued Internet connectivity by transporting user’s data between users’ current SGSN and GGSN
GPRS support nodes (GSN) GGSN - Gateway GPRS Support Node SGSN - Serving GPRS Support Node
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.
UMTS and 3G technologies (WCDMA & HSPA)
Universal Mobile Telecommunications System (UMTS) – commonly uses WCDMA as the underlying interface
Theoretically supports up to 14 Mbps rates with HSDPA
WCDMA 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 on downlink(1.8. 3.6, 7.2, 14.0 Mbps via AMC, and HARQ, fast packet scheduling.
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
Next Generation Mobile Networks
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.
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 30-50 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
NGMN Envisioned System Architecture
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
Alternative fixed wireless and MAN standards
WiMAX, the Worldwide Interoperability for Microwave Access based on IEEE 802.16 standard
Last-mile broadband access, backhaul for cellular networks, Internet Services
802.16d Fixed WiMAX, 802.16e - Mobile WiMAX.
Licensed spectrum profiles: 2.3GHz, 2.5GHz and 3.5GHz. US mostly around 2.5 GHz, assigned primarily to Sprint Nextel, Clearwire.
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 utilitiesSystem design and networking challenges
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
Cellular Networks and Internet
Cellular Networks Internet
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 Services Operator initiated or partnered
Third party/ independent (largely)
Cellular Networks and Internet
Cellular Networks Internet
Data rates for supporting broadband services
Insufficient as of present
Relatively high
Cost per MB of data
HigherLower
QoS at edges Good Support (voice vs. data)
Mostly absent
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?
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.
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
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.
Agenda Basics & Technology Evolution Architecture and Functionality (GSM, 3G
and beyond) Cellular future goals Emerging trends
Alternative wireless access technologiesConvergence
Comparison with Internet and sample scenario studies
Economics of operation From a clean slate
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.
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.