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Transcription

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2 GSM Overview Services GSM Architecture GSM Air Interface GSM Logical Channels - 2 -

3 formerly: Groupe Spéciale Mobile (founded 1982) by CEPT (Conférence Européenne des Administrations des Postes et des Télécommunications) now: Global System for Mobile Communication (GSM) and ETSI European Telecommunications Standards Institute 1992 two physically and organisationally separated networks start in Germany D1 and D2 and in a number of further European countries seamless roaming within Europe possible today many providers all over the world use GSM (more than 200 countries in Asia, Africa, Europe, Australia, America) more than 1 billion subscribers more than 70% of all digital mobile phones use GSM over 19 billion SMS per year in Germany, > 360 billion/year worldwide

4 - 4 - Quelle: RegTP,

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7 ! Quelle: RegTP,

8 T-Mobile (GSM-900/1800) Berlin " Vodafone (GSM-900/1800) e-plus (GSM-1800) O 2 (GSM-1800) (

9 Extensions: HSCSD, GPRS, EDGE GSM900, GSM1800, GSM1900, GSM400, GSM-R GSM-R (Rail): separate frequency, voice group calls, voice broadcast services, emergency calls with acknowledgement, control functionality of signals, switches, high speed - 9 -

10 # $!"! # ")* $%&' ( implementation of UMTS in Europe from ca in Japan UMTS has been established since 2001 other techniques in the USA

11 % Data transmission standardized with only 9.6 kbit/s advanced coding allows 14,4 kbit/s not enough for Internet and multimedia applications HSCSD (High-Speed Circuit Switched Data) mainly software update bundling of several time-slots to get higher AIUR (Air Interface User Rate) (e.g., 57.6 kbit/s using 4 slots, 14.4 each) advantage: ready to use, constant quality, simple disadvantage: channels blocked for voice transmission AIUR [kbit/s] TCH/F4.8 TCH/F9.6 TCH/F

12 &' GPRS (General Packet Radio Service) packet switching using free slots only if data packets ready to send (e.g., 50 kbit/s using 4 slots temporarily) standardization 1998, introduction 2001 advantage: one step towards UMTS, more flexible disadvantage: more investment needed (new hardware) GPRS network elements GSN (GPRS Support Nodes): GGSN and SGSN GGSN (Gateway GSN) interworking unit between GPRS and PDN (Packet Data Network) SGSN (Serving GSN) supports the MS (location, billing, security) GR (GPRS Register) user addresses

13 &' () Reliability class Lost SDU probability Duplicate SDU probability Out of sequence SDU probability Corrupt SDU probability Delay SDU size 128 byte SDU size 1024 byte class mean 95 percentile mean 95 percentile 1 < 0.5 s < 1.5 s < 2 s < 7 s 2 < 5 s < 25 s < 15 s < 75 s 3 < 50 s < 250 s < 75 s < 375 s 4 unspecified

14 &' Active Slots Uplink Slots Downlink Slots Multislot Class

15 &' # ' * Coding scheme 1 slot 2 slots 3 slots 4 slots 5 slots 6 slots 7 slots 8 slots CS CS CS CS

16 &' +!, SGSN G n MS BSS SGSN GGSN PDN U m G b G n G i MSC HLR/ GR VLR EIR

17 &'! ) MS has to register with Mobility Management MS gets a Temporary Logical Link Identitiy, TLLI and a Ciphering Key Sequence Number CKSN A GPRS context is created for each MS in SGSN context comprises status (ready, idle, standby), CKSN, routing information (TLLI, Routing Area, cell ID, PDCH ID) PDTCH Packet Data TCH, one MS can use up to 8 PDTCH

18 &' & + MS U BSS m G SGSN b G GGSN n G i apps. IP/X.25 IP/X.25 SNDCP SNDCP GTP GTP LLC LLC UDP/TCP UDP/TCP RLC RLC BSSGP BSSGP IP IP MAC MAC FR FR L1/L2 L1/L2 radio radio SNDCP: Subnetwork Dependent Convergence Protocol GTP: GPRS Tunnel Protocol BSSG: BSS GPRS Protocol

19 Slides and Lectures are based on: J. Schiller, Mobilkommunikation, Pearson Studium, 2003 K. David, T. Benkner, Digitale Mobilfunksysteme, Teubner 1996 Very detailed and more info: B. H. Walke: Mobile Radio Networks, Wiley,

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