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Wireless Data Communication Networks Lecture 21: GSM evolution

Wireless Data Communication Networks Lecture 21: GSM evolution. Outline. Evolution of GSM into a packet data network. GSM Evolution path . GSM – migrates towards packet data networks with broadband access air interface. Driver behind the migration – change in the use model for GSM networks.

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Wireless Data Communication Networks Lecture 21: GSM evolution

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  1. Wireless Data Communication Networks Lecture 21: GSM evolution

  2. Outline • Evolution of GSM into a packet data network

  3. GSM Evolution path GSM – migrates towards packet data networks with broadband access air interface Driver behind the migration – change in the use model for GSM networks

  4. Cellular data networks – throughput comparison

  5. GPRS Network Architecture • GPRS introduces new entities to support data packet transmissions • New entities are PCU, GSN, Border Gateway, and GPRS register

  6. GSM/GPRS – put together

  7. GPRS/EDGE – MCS and throughputs • GPRS and EDGE introduce multiple Modulation and Coding Schemes (MCS) • MCS allows different data rates through the GSM time slot • Selection of MCS depends on channel condition and capability of mobile • GPRS and EDGE allow for multiple slot aggregation • Slot aggregation allows increase in data rate offered to the user • EDGE introduces new modulation scheme – 8-PSK GPRS MCS EDGE MCS Note: EDGE supports both GMSK and 8-PSK PHY throughput for different MCS

  8. UMTS architecture • W-CDMA air interface for UMTS radio Access • Air interface is based on CDMA access • Reuse of the existing GSM network architecture • Iub fully standardized • The core network allows both GSM and UMTS radio access Acronyms: Node B = Base Station SGSN = Service GPRS Node GGSN = Gateway GPRS Node MSC = Mobile Switching Center VLR = Visitor Location Registry HLR = Home Location Registry Open Interfaces: Uu – W-CDMA air interface Iub – Node B to RNC Iur – between RNC Iu – between UTRAN and CN Page 8

  9. Property Value Access scheme DS-CDMA with FDD and asynchronous operation Bandwidth 5MHz Chip rate 3.84 Mc/second Spreading Variable: UL 1-512 (power of 2), DL(1-256) Single code user rates UL (after coding) 15,30,60,120,240,480, 960 kb/sec Up to 6 code aggregation Single code user rates DL(after coding) 15,30,60,120,240,480, 960, 1920 kb/sec Up to 3 code aggregations Frame Length 10ms Power control Open loop and closed loop with 1500 commands/sec Detection Coherent on both UL and DL Diversity support DL TX Diversity, DL and UL RAKE receiver reception, UL space diversity UMTS Radio Interface • Air interface determines the performance of a cellular system • W-CDMA – revolutionary change from GSM’s TDMA scheme • Advanced radio resource management – required by diverse 3G applications • Multi-rate spreading • W-CDMA is interference limited • Provides soft capacity and • Coverage, capacity, qualitytradeoffs Summary of W-CDMA properties W-CDMA Scheme UL – Uplink, DL - Downlink Page 9

  10. Long Term Evolution (LTE) • LTE – 4 G technology • Changes in both radio access and core • Radio access is OFDM based (1.4-20MHz) • Core is packet only; Voice as VoIP • Simplified core – all IP • eNodeB responsible for RRM

  11. Review • List successor technologies to GSM • How is voice handled in GSM (as CS or as PS) • Which technology promises higher data rates: EDGE or HSPA? • What type of access scheme is used in UMTS? • What type of access scheme is used in LTE? • Does LTE core network contain switches? • How is voice handled in LTE? • Explain the concept of adaptive MCS

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