18-759: Wireless Networks L ecture 17: Cellular Peter Steenkiste - PDF document

18-759: Wireless Networks L ecture 17: Cellular Peter Steenkiste Departments of Computer Science and Electrical and Computer Engineering Spring Semester 2010 http://www.cs.cmu.edu/~prs/wirelessS10/ 1 Peter A. Steenkiste, CMU Outline � Cellular landscape p � AMPS � GSM » HSCSD » GPRS » EDGE � CDMA � OFDM Some slides provided by Rui Aguiar University of Aveiro 2 Peter A. Steenkiste, CMU Page 1

The Cellular Landscape 5-10 bps/Hz 0.15bps/Hz 0.30 bps/Hz Max. rate ~ Max.rate 64Kbps Max.rate 2 Mbps 100Mbps/1Gbs p FDMA FDMA TDMA &CDMA TDMA &CDMA TDMA,CDMA and WCDMA TDMA CDMA d WCDMA WCDMA 4G 2G Smart antennas? 2.6G/3G 1G Digital Modulation MIMO? Hierarchical cell structure Analog Convolution coding Adaptive Systems Turbo-coding Power Control OFDM Modulation AMPS PDC EDGE GSM Cdma2000 TACS HSCSD WCDMA/UMTS NMT GPRS 3G 1x EV-DO C-450 IS-54/IS-136 3G 1X EV-DV IS-95/IS-95A/IS-95B PHS 3 Peter A. Steenkiste, CMU Cellular Standards � 2G systems: digital voice y g » GSM - FDMA/TDMA, most widely deployed, 200 countries, a billion people » IS-95 - first CDMA-based cellular standard, developed by Qualcomm » IDEN - TDMA, Nextel, merged with Sprint, being phased out for CDMA2000 » IS-136 - uses FDMA/TDMA, North America, Cingular and US Wireless, being phased out for GSM, CDMA2000 US Wireless, being phased out for GSM, CDMA2000 � 2.5G systems: voice and data channels » GPRS - evolved from GSM, packet-switched, 170 kbps (30-70 in practice) » CDMA2000 1xRTT - evolved from IS-95, 144 kbps 4 Peter A. Steenkiste, CMU Page 2

Cellular Standards � 2.75G - almost 3G in speed p » EDGE - another enhancement of GSM, 384 kbps, 2.75G » Thanks to new modulation scheme (8PSK) – may coexist with GMSK � 3G: voice (circuit-switched) and data (packet- switched) » UMTS - W-CDMA, successor to GSM networks, 384 kbps - 2 Mbps, European, some Japan, Cingular in U.S. » CDMA2000 1xEV - CDMA2000 with high data rates - 3.1 Mbps up, 1.8 Mbps down, U.S., Japan, Korean, Canada – Verizon, Sprint � 4G: 10 Mbps and up, seamless mobility between di fff erent cellular technologies, mesh, etc. 5 Peter A. Steenkiste, CMU GSM Evolution � Messages » SMS – Short Message Service » News » USSD – Unstructured Supplementary Service Data � Data: » HSCSD – High Speed Circuit-Switched Data » GPRS – General Packet Radio Service » Edge – Enhanced Data Rate for GSM Evolution » Edge – Enhanced Data Rate for GSM Evolution » UMTS – Universal Mobile Telecommunication System 6 Peter A. Steenkiste, CMU Page 3

HSCSD � Based on fast circuit switching, introduced in phase 2+ (1997) 2+ (1997). » Non optimum solution for packets (cost/capacity) � Same GSM layers » Same interoperation function in MSC, » same transport network � Uses multiple time slots per user (max 6) » Changes link level protocol » Bitrates: 19.2 ; 28.8 ; 28.4 ; 48 ; 56 and 64 kb/s. » Asymmetric configurations (n slots on the uplink and m slots on the downlink). » Increases blocking probability of the system 7 Peter A. Steenkiste, CMU GPRS � General Packet Radio Service � Packet-oriented transport service, for data network connections (Internet) � GPRS features: » Better transmission bit rates(max 150kbps). » Allows burst communications (“immediate”: connections in <1s) » New network applications » New billing mechanisms (user-oriented: by traffic, p.ex.) » New billing mechanisms (user-oriented: by traffic p ex ) 8 Peter A. Steenkiste, CMU Page 4

GPRS principles GPRS principles � Transmission of non-periodic and bursty data (e.g.: mails ), � F � Frequent small packets (e.g.: telematic , billing and micro-payments ), t ll k t ( t l ti billi d i t ) » Large but unfrequent packets (e.g.: ftp ). � Higher bit-rates per TCH (9.05 ; 13.4 ; 15.6 ; 21.4 kb/s), � Higher bit-rates with up to 8 time slots per user, � Channel sharing by active terminals, � Separate allocation of uplink and downlink channels, � Separate packet transmission network between the BSC and external packet transmission networks: GSS (based on SGSN and GGSN). � GSS: GPRS SubSystem 9 Peter A. Steenkiste, CMU GPRS Architecture � New entities are defined � SGSN – serving GPRS support node SGS g G S pp � GGSN – gateway GPRS support node � Interfaces between entities GPRS, GSM, core, e PSTN � Transmission plane � Data packets are transmitted by a tunnel mechanisms � Control plane � GTP: a protocol for tunnel management (create, remove, etc..) � GTP: a protocol for tunnel management (create remove etc ) � GPRS Tunnel Protocol � Radio interface � Changes the logical channels and how they are managed � Keeps the concept of “master-slave” 10 Peter A. Steenkiste, CMU Page 5

GPRS Architecture Other GPRS networks networks SGSN SGSN GGSN Gp BSC Gn BTS Gb Gf Gr BTS Gs Gi Gc MT GGSN PDN EIR D D HLR MSC/VLR SGSN – serving GPRS support node GGSN – gateway GPRS support node 11 Peter A. Steenkiste, CMU GPRS introduction in a GSM network IN Plate-form PSTN BTS A bis TRAU ... . A . . < ^ > .. BTS BSC HLR BTS MSC/VLR MSC/VLR PCU G r G s G b G r , G d , G f SGSN EIR SS7 Network G n G f GPRS Border Border backbone backbone S Service i WAP WAP, Gateway G c WWW, plate-form ... Router Internet GGSN LAN PDN Inter-operator GPRS backbone 12 Peter A. Steenkiste, CMU Page 6

GSM to GPRS Evolution BSS Evolution : • Replace/Upgrade existing elements: BTS, BSC, Replace/Upgrade existing elements: BTS, BSC, O&M, Network planning, Links (Abis, Ater, …). • New element: PCU ( Packet Controller Unit ). NSS Evolution • A new core network (GSS) dedicated to GPRS: IP/ATM based, network packet nodes (SGSN,GGSN), Internet equipment (DNS servers, Firewalls, …). • Evolution of the network elements: HLR, MSC/VLR, SS7. 13 Peter A. Steenkiste, CMU GGSN ( Gateway GPRS Support Node ) Functions � Gateway: » Allows the connection to other IP or GPRS networks. All th ti t th IP GPRS t k � Routing : » IP router which supports dynamic or static routing, � Mobility management: » Use of routing areas . » Handover management between the BSCs and other SGSNs. » Allows the routing of the packets towards the users SGSNs, All th ti f th k t t d th SGSN according to their mobility. � Sessions management: » At each session, the SGSN activates a PDP ( Packet Data Protocol ) context, and allocates an IP address to the MT. 14 Peter A. Steenkiste, CMU Page 7

GGSN ( Gateway GPRS Support Node ) Functions � Security: » Ciphers the communications towards or from the » Ciphers the communications towards or from the mobiles. » Includes firewalls for filtering the packets coming from external IP networks. � Authentication: » At Attach and inter-SGSN RA updates. � Billing: » Production of the CDRs according to the quantity of information and the session duration (attachment, duration of active PDP context). � SMS: » Supports the Gd interface for the communications with the SMS-GMSC and the SMS-IWMSC. 15 Peter A. Steenkiste, CMU MT Registration There is an explicit registration of the MT in the network: network: » GPRS attach » GPRS detach – can be started by the MT or by the network » Location packets are periodically sent � HLR (modified!) keeps information on the MT status, including: » GPRS state (ready, standby, idle) » GPRS state (ready, standby, idle) » QoS profile (priority 3, delay 4, reliability 5, throughput peak 9 and media 19) » Context PDP (Packet Data Protocol) – Also stored in GS and in the GGSN and SGSN 16 Peter A. Steenkiste, CMU Page 8

Connection Management After attach: receive a packet with a PDP identifier Acts as an address Acts as an address PDP identifier: per session. – static: allocated by the MT home networks – Dinamic: allocated by the GGSN PDP profile: Type PDP identifier de t e Requested QoS correspondent GGSN address 17 Peter A. Steenkiste, CMU PDP context activation MT SGSN GGSN Activate PDP Context Request PDP type,PDP Address QoS Requested ,Access Point,… Security Functions Create PDP Context Request PDP type,PDP Address QoS Negotiated,Access Point,… Q S N ti t d A P i t Create PDP Context Response Activate PDP Context Accept PDP type,QoS Negotiated,… PDP type,PDP Address QoS Negotiated ,… 18 Peter A. Steenkiste, CMU Page 9

GPRS Radio Interface Time Slot 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 0 0 1 1 2 2 3 3 4 4 F1 Uplink F2 F3 F4 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 0 0 1 1 2 2 3 3 4 4 Carrier F1 frequency frequency F2 Downlink F3 F4 User1 Voice User3 GPRS User5 GPRS User2 Voice User4 GPRS 19 Peter A. Steenkiste, CMU GPRS: logical channels Group p Channel Function Direction Packet data PDTCH Data Traffic MS BSS Traffic channel Packet broadcast PBCCH Broadcast Control MS BSS control channel PRACH Random Access MS BSS Packet common PAGCH Access Grant MS BSS Control Channel Control Channel PPCH Paging MS BSS (PCCCH) PNCH Notification MS BSS PACCH Associated Control MS BSS Packet Dedicated Control Channels PTCCH Timing Advance Control MS BSS 20 Peter A. Steenkiste, CMU Page 10