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“Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks”

“Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks”. Romano Fantacci Full Professor Francesco Chiti Ph.D. Department of Electronics and Telecommunications University of Florence Via di S. Marta, 3 I-50139 Florence, ITALY

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“Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks”

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  1. “Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks” Romano Fantacci Full Professor Francesco Chiti Ph.D. Department of Electronics and Telecommunications University of Florence Via di S. Marta, 3 I-50139 Florence, ITALY E-mail: {fantacci,chiti}@lenst.det.unifi.it Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  2. Introduction Soft combining principle Soft Input Combining Soft Output Combining Theoretical analysis AWGN Multipath fading channel Application to UMTS systems Conclusions Outline Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  3. Soft Combining techniques UMTS/HSDPA Conversational Streaming Interactive Background LLC MAC PHY Service Classes i. Introduction IPvx • Elastic • Stream DiffServ • Expedited Forward • Assured Forward • Best Effort Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  4. Soft Combining techniques Automatic Repeat reQuest (ARQ) protocols Erroneous packets detection by means of a CRC; Packet retransmission through dedicated signals (ACK/NACK) Stop and Wait (SW), Go Back N (GBN), Selective Repeat (SR). Forward Error Correction (FEC) techniques Erroneous packet correction by means of a suitable channel code (convolutional codes; turbo codes). Reliable packet communications i. Introduction Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  5. Soft Combining techniques Traditional approaches comparison i. Introduction Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  6. Soft Combining techniques Hybrid ARQ (H-ARQ) approaches Type I channel coding and retransmission mechanism are merely integrated within the same scheme Type II traditional approaches are harmonized and jointly optimized by keeping trace of transmission/reception process (e.g. Chase Combining) Type III transport formats are dynamically updated to cope with the signal quality variations (e.g. Incremental Redundancy) Soft Combining (MAC+LLC) Acknowledgement Driven (PHY+MAC+LLC) i. Introduction Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  7. Soft Combining techniques p DEMUX Decoder Receiver p Despreading BCJR BCJR Rake Buffer Demodulator LOGIC -1 Descrambling p 1. Soft combining principle Functional block diagram Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  8. Soft Combining techniques Packet replicas are combined via a soft metric, maximizing the Euclidean distance among symbols; Combination schemes follow a diversity technique: Maximum Ratio Combining (MRC); Equal Gain Combining (EGC); Weighted Gain Combining (WGC). Diversity gain is advantageously considered Soft Input Combining H-ARQ 1. Soft combining principle Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  9. Soft Combining techniques Last packet replica is combined via a soft metric to the decoding process outputs, maximizing the Euclidean distance among codewords; Suitable for SISO decoder (turbo principle) Combination schemes follow a diversity technique: Maximum Ratio Combining (MRC); Equal Gain Combining (EGC); Weighted Gain Combining (WGC). Diversity gain and decoding gain are considered 1. Soft combining principle Soft Output Combining H-ARQ Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  10. Soft Combining techniques under Gaussian output approximations (except for interdiction and saturation regions) • Coding gain: • : output combining • : input combining OUT IN 1. Soft combining principle Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  11. Soft Combining techniques ACK/NACK CRC adder CRC Pack CRC Pack Redundancy Coder Modulator 1. Soft combining principle Transmitter protocol stack Layer II - LLC Pack New Frame Previous Frame Logic Buffer Layer II - MAC Layer I -PHY Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  12. Soft Combining techniques ACK/NACK CRC Pack Previous OUTPUT ACK/NACK Logic Previous INPUT CRC check CRC Pack Redundancy Buffer Decoder Demodulator 1. Soft combining principle Receiver protocol stack Layer II - LLC Pack Layer II - MAC Layer I -PHY Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  13. Soft Combining techniques BER SOC outperforms SIC 2. Theoretical analysis AWGN channel • Soft Input Combining • Soft Output Combining Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  14. Soft Combining techniques FER frame length 2. Theoretical analysis AWGN channel • Average needed retransmissions • Throughput Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  15. Soft Combining techniques BERk • Soft Input Combining • Soft Output Combining 2. Theoretical analysis Multipath fading channel joint pdf of kL fading coefficients (1kL) Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  16. Soft Combining techniques BER 2. Theoretical analysis Multipath fading channel • FER Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  17. Soft Combining techniques Goodput multiplicative increase/multiplicative decrease SLW congestion control 2. Theoretical analysis Multipath fading channel Initial SLW size Prob that current block has been transmitted K times at time n Timeout valueis equal to K(RTT) Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  18. Soft Combining techniques UMTS uplink (3GPP complain); Bit rate: 30 kb/s – 120 kb/s; Turbo coder/decoder: (1,15/13)8 ; R=1/2; MAP-BCJR. Interleaver (3GPP complain); ETSI urban channel (6 paths). 3. Application to UMTS systems Operative assumptions Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  19. Soft Combining techniques 3. Application to UMTS systems Frame Error Rate Better FER(QoS) orreduced power wasting(lesser electromagnetic pollution) Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  20. Soft Combining techniques 3. Application to UMTS systems Throughput Better FER(QoS) orbetter throughputorreduced delay Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  21. Soft Combining techniques 3. Application to UMTS systems Cell capacity (64 nominal users) Capacity increasingup to 20 oversaturated users () Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  22. Soft Combining techniques 3. Application to UMTS systems Goodput Reduced powerorhigher effective bandwidth Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  23. QoS oriented services within wireless networks Cross-layer adaptive protocols design for reliable applications Soft Combining techniques (H-ARQ type II) Analytical performance evaluation Application to 3G public systems (UMTS) Conclusions Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  24. F. Chiti, R. Fantacci, F. Versaci: “Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks”, Annals of Telecommunications: Special Issue on Turbo Codes, January 2005. F. Chiti, R. Fantacci, F. Versaci: “An Efficient Turbo Soft Combining Hybrid ARQ Techniques for Application in Wireless Communication Systems”, IEEE Trans. on Comm., submitted for publication. F. Chiti, R. Fantacci: “A Soft Combining Hybrid ARQ Technique applied to Throughput Maximization within 3G Satellite IP Networks”, IEEE Trans. on Vehic. Tech., submitted for publication. Journal papers Publications Conference papers • F. Chiti, R. Fantacci, T. Pecorella, F. Versaci: “Soft Combining Hybrid ARQ Techniques Application to Packet Communications within 3G Wireless Networks”, in Proc. of IEEE WCNC 2003. • F. Chiti, R. Fantacci, T. Pecorella, F. Versaci: “Soft Combining Hybrid ARQ Techniques Application to 3G Wireless Networks”, in Proc. of IEEE ICC 2003. • F. Chiti, R. Fantacci, G. Mennuti, D. Tarchi: “Dynamic SIR based Admission Control Algorithm for 3G Wireless Networks”, in Proc. of IEEE ICC 2003. • F. Chiti, R. Fantacci, F. Versaci: “Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks”, in Proc. of IEEE ISTC 2003. Laboratorio di Elaborazione Numerica dei Segnali e Telematica

  25. “Turbo Soft Combining Hybrid ARQ Techniques: Theory and Application to 3G Wireless Networks” Romano Fantacci Full Professor Francesco Chiti Ph.D. Department of Electronics and Telecommunications University of Florence Via di S. Marta, 3 I-50139 Florence, ITALY E-mail: {fantacci,chiti}@lenst.det.unifi.it Laboratorio di Elaborazione Numerica dei Segnali e Telematica

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