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1 Xu, R., Koçak, T., Woodward, G., & Morris, KA. (2010). Throughput improvement on bidirectional Fano algorithm. In 6th International Wireless Communications and Mobile Computing Conference, Caen, France (pp ). Institute of Electrical and Electronics Engineers (IEEE). DOI: / Peer reviewed version Link to published version (if available): / Link to publication record in Explore Bristol Research PDF-document University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available:

2 Throughput Improvement on Bidirectional Fano Algorithm Ran Xu *, Taskin Kocak *, Graeme Woodward and Kevin Morris * *Centre for Communications Research, Department of Electrical and Electronic Engineering, University of Bristol, Bristol BS8 1UB, UK Telecommunications Research Laboratory, Toshiba Research Europe Ltd, 32 Queen Square, Bristol BS1 4ND, UK Centre for Communications Research

3 Outline Introduction 60 GHz radio High throughput decoding Sequential decoding algorithms Throughput Improvement on BFA Bidirectional Fano algorithm Trade-offs in the BFA Construction of the {NMS, } look-up table Simulation Results Simulation setup BER, TI and Computational complexity Conclusions

4 Introduction(1/3) 60 GHz radio 5-7 GHz unlicensed bandwidth around 60 GHz Multi-gigabit per second (1~6Gbps) data rate Uncompressed video streaming, large file transfer and etc. Fig. 1 Configuration of gigabit WPANs in a typical home environment [1] IEEE c, WiGig, WirelessHD and etc.

5 Introduction(2/3) High throughput decoding Eight parallel Viterbi decoders-high computational complexity and hardware complexity Other convolutional codes decoding algorithms-sequential decoding Fig. 2 Rx in the WirelessHD system with eight parallel convolutional decoders [2]

6 Introduction(3/3) Sequential decoding algorithms look forward to best; Stack algorithm [3] -Large memory -Sorting operations t-1 S t-1,0 t t+1 S t,0 S t+1,0 If max(mf1,mf2)>=t move forward & tighten T by ; Else look back; Fano algorithm [4] -Small memory -No sorting operations S t,1 S t+1,1 If MB>=T move backward & T=MB; look forward to next best; Else T=T- ;

7 Throughput Improvement(1/3) Bidirectional Fano algorithm FD and BD More than two times decoding throughput improvement Slightly error rate performance degradation Throughput improvement converges to 100% at high SNR Fig. 3 Illustration of bidirectional Fano algorithm decoding, where L is the information length and K is the constraint length of the convolutional code. The more rigorous merging check requires more than one merged state and the overlapped length should be not less than 1. [5]

8 Throughput Improvement(2/3) Trade-offs in the BFA Number of merged states (NMS) Table 1 BER (x10-3 ) look-up table Threshold increment value Table 2 TI look-up table Fig. 4 BER and Throughput Improvement for differnet NMS and at Eb/No=4dB

9 Throughput Improvement(3/3) Construction of the {NMS, } look-up table Step 1: Set NMS=[NMS 1,,NMS I ] and =[ 1,, J ]; Step 2: Get empirical statistics of BER IJ and TI IJ by simulations in the considered environment; Step 3: Find the indexes of the BER IJ matrix whose values are below or equal to the target BER; Table 3 Optimal pairs of NMS and in the BFA Step 4: Find the index of the TI IJ matrix whose value is the maximum; Step 5: The NMS and corresponding to the maximum TI is selected.

10 Simulation Results(1/3) Simulation setup Table 4 Simulation setup

11 Simulation Results(2/3) BER, TI and Computational complexity BER Throughput Improvement Computational complexity Fig. 5 BER comparison

12 Simulation Results(3/3) BER, TI and Computational complexity Fig. 6 TI comparison Fig. 7 Computational complexity comparison

13 Conclusions Sequential decoding in high throughput systems Trade-offs in the BFA caused by NMS and {NMS, } look-up table construction More than 100% throughput improvement at high SNR

14 References [1] H. Singh, J. Oh, C. Kweon, X. Qin, H.-R. Shao and C. Ngo. A 60 GHz wireless network for enabling uncompressed video communication. IEEE Communications Magazine, vol. 46, no. 12, pp , [2] Wireless High-Definition (WirelessHD); [3] F. Jelinek. Fast sequential decoding using a stack. IBM J. Res. Devel., vol. 13, pp , Nov [4] R. M. Fano. A heuristic discussion of probabilistic decoding. IEEE Transactions on Information Theory, vol. IT-9, no. 2, pp , Apr [5] R. Xu, T. Kocak, G. Woodward, K. Morris and C. Dolwin. Bidirectional Fano Algorithm for High Throughput Sequential Decoding. IEEE Symp. On Personal, Indoor and Mobile Radio Communications (PIMRC), Tokyo, Japan, 2009.

15 Thank you for your attention! Q&A