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Simulazione di protocolli a pacchetto per reti radiomobili: GPRS ed UMTS

Simulazione di protocolli a pacchetto per reti radiomobili: GPRS ed UMTS. Alberto Bona, Maurizio Conti. Politecnico di Torino. Simulator purposes. Analyzing GPRS and UMTS performances on radio interface in presence of different traffic sources

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Simulazione di protocolli a pacchetto per reti radiomobili: GPRS ed UMTS

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  1. Simulazione di protocolli a pacchetto per reti radiomobili:GPRS ed UMTS Alberto Bona, Maurizio Conti Politecnico di Torino

  2. Simulator purposes • Analyzing GPRS and UMTS performances on radio interface in presence of different traffic sources • Implementing MAC layer source code for both GPRS and UMTS systems • Comparing simulation and theoretical model results • Creating a software instrument open to future developements and extensions 2 Alberto Bona, Maurizio Conti

  3. Simulator description • General features • Simulation environment • BTS features • GPRS simulator structure • BTS structure • MS structure • GPRS simulations • traffic sources • results 3 Alberto Bona, Maurizio Conti

  4. General features • Programming language: C++ • Simulator type: synchronous + events • Main interest for “higher” layer protocol performances • Simplified physical layer model • Closed topology • Simultaneous presence of UL and DL MS ETSI and 3GPP standards + technical papers REFERENCE DOCUMENTS 4 Alberto Bona, Maurizio Conti

  5. Simulation environment • Based on suburban model defined in UMTS 30.03: • Base station distance: 6 or 1.5 km • Cell radius: 2 km or 500 m • Simulations of other environments are not precluded: • changing base station distance and cell radius • changing propagation model • Users mobility: • Every position update, users step from current pixel to an adjacent one 5 Alberto Bona, Maurizio Conti

  6. BTS features • Each BTS can be equipped with both omnidirectional and sectorial antennas • Irradiation diagram is specified by an input file • Propagation model: 6 Alberto Bona, Maurizio Conti

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  8. GPRS-BTS structure • PRACH-controller: • responsible for MS UL access • RSC-allocator: • responsible for resource allocation • Dyn_matrix: maintains information about Dynamic and Extended dynamic allocation (USF) • Fixed_matrix: stores channel occurrences (PRACH, PAGCH) and MS fixed-allocation • PDCH status: carries information about PDCH status (GSM or GPRS) • Dyn, E-Dyn, Fixed_alloc: implement allocation algorithms 8 Alberto Bona, Maurizio Conti

  9. GPRS-BTS structure • TX-allocator: • responsible for frame scheduling • schedulation is performed at the beginning of each block • transmission is performed frame by frame • TX_matrix: stores information about the block owner, either a controller or a MS • Dyn, E-dyn, fixed_sched: perform algorithms for PDCH condivision through RSC information 9 Alberto Bona, Maurizio Conti

  10. GPRS MAC MS structure • MAC-buffer: stores MAC-blocks ready for transmission and controls access to uplink PDCH • Header: inserts header to RLC-PDU, updating fields for statistics • PRACH-controller: responsible for access procedures 10 Alberto Bona, Maurizio Conti

  11. Simulations Validation test Resource sharing between GPRS and GSM (1 carrier) GPRS traffic multiplexing on 1 PDCH GPRS traffic multiplexing on 7 PDCH COMMON FEATURES • Dynamic allocation • Round-Robin schedulation Alberto Bona, Maurizio Conti

  12. GPRS traffic sources • ON-OFF status length is negative exponentially distributed • Mean time ON/OFF: 20/40 s • Mean time between packet: 500 ms • Packet length depends on offered bit rate: • 1.9, 6.4, 11.2, 19.2, 64 kbit/s (peak) • CS3 coding scheme • Packets are segmented by RLC and passed to MAC layer Alberto Bona, Maurizio Conti

  13. Performance parameters GPRS blocking probability GSM blocking probability Access delay (UL) MAC block transfer delay Session throughput IP packet throughput Alberto Bona, Maurizio Conti

  14. Validation test Alberto Bona, Maurizio Conti

  15. Resource sharing between GSM and GPRS (1 carrier) GSM sources Mean call length 1/m. = 120 s Mean call interarrival time 1/l Offered loadl/m= M = 2, …, 8 100 users per cell GPRS sources Offered load per user: 6.4, 11.2, 19.2 kbit/s (peak) 4 users per cell Alberto Bona, Maurizio Conti

  16. Resource sharing Alberto Bona, Maurizio Conti

  17. Resource sharing Alberto Bona, Maurizio Conti

  18. Resource sharing Alberto Bona, Maurizio Conti

  19. Resource sharing Alberto Bona, Maurizio Conti

  20. Only GPRS traffic multiplexing No GSM sources Multiplexing on 1 PDCH: Offered load per user: 1.9, 6.4, 11.2, 19.2 kbit/s (peak) 1, 2, …, 10 users per cell Multiplexing on 7 PDCH: Offered load per user: 11.2, 19.2 kbit/s (peak) 1, 5, 10, …, 25 users per cell Alberto Bona, Maurizio Conti

  21. Multiplexing on 1 PDCH Alberto Bona, Maurizio Conti

  22. Multiplexing on 1 PDCH Alberto Bona, Maurizio Conti

  23. Multiplexing on 1 PDCH Alberto Bona, Maurizio Conti

  24. Multiplexing on 7 PDCH Alberto Bona, Maurizio Conti

  25. Multiplexing on 7 PDCH Alberto Bona, Maurizio Conti

  26. Multiplexing on 7 PDCH Alberto Bona, Maurizio Conti

  27. Multiplexing on 7 PDCH Alberto Bona, Maurizio Conti

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