高傳輸率維特比解碼器

High Throughput Viterbi Decoder

李後璋(Ho-Chang Lee)

指導教授 ： 江正雄

淡江大學/工學院/電機工程學系碩士班/碩士(2004年)

https://doi.org/10.6846/TKU.2004.00006

摘要

此篇論文主要在陳述一種新的維特比解碼器的架構，目的在提高原有IS-95, IS-2000, 8021.x 的傳輸率。因原本既有的標準，都是使用較高的輸入頻率來達成標準內的傳輸率，或者使用較低的輸入頻率，再用內部的PLL，提供出較高的觸發頻率給內部的維特比解碼器來達成。但是在新的802.11x標準內，已將輸入觸發頻率與傳輸率，幾乎相等，如802.11a/b/g或將出爐的802.11、802.16a。但這些標準都必須使用到維特比解碼器。為了這些標準，此篇論文提供一種新的架構，不需要PLL，也不需較高的觸發頻率，既可達到新標準的傳輸率。
就原IS-95標準，其輸入頻率為10MHZ，-而其傳輸率為1.22Mbps，如果使用此架構，可將其傳輸率提升至40Mbps，其改善倍率將近32倍。如果以IS-2000為比較 (3.1Mbps)，此架構的改善倍率，亦可達到12倍之多。而如果以現存的802.11 a/b/g，可將其原有的輸入觸發頻率40MHZ降至10MHZ，其輸傳輸率仍可維持在27Mbps，甚至達到40Mbps。並且在未來的802.11n標準下，其傳輸率必須達到100Mbps，如輸入頻率維持在40MHZ，此架構可提供到160Mbps傳輸率，仍然遠超過802.11n的標準。而且於生還者路徑(Trace Back Unit)的單元中，也將可大幅減少其所佔積體電路的面積。

關鍵字

維特比 ； 解碼器 ； 維特比解碼器

並列摘要

This thesis describes a new structure of the Viterbi Decoder for IS-95, IS-2000, 802.11x. Originally, higher input trigger frequency or lower input frequency for Viterbi Decoder were used to meet the transitions requirements. Nowadays, input trigger frequency almost equals to the transmitting rate in new 802.11x standard, such as 802.11a/b/g,802.11n,and 802.16a .This new VD structure does not need PLL, nor rising input trigger frequency to meet the transmission rate of the new standard.
Original IS-95 standard, its inputs trigger frequency is 10MHZ, but the general transmission rate is 1.22Mbps. If we use this structure, the transmit rate will be improved to 40Mbps, nearly 32 times faster than the original as well as IS-2000 standard (3.1Mbps), it improves nearly 12 times. Moreover, as for existing 40MHZ 802.11 a/b/g input trigger frequency, it can be done by 10MHz resulting 27Mbps transmitting rate. For future 802.11n standard, when transmitting rate must reach 100Mbps, its input trigger frequency can still be kept at 40MHZ. This input trigger frequency can even offer a transmitting rate up to 160Mbps for the 802.11n standard. As the result, the decoder has achieved a higher decoding rate without any degradation in performance. One result also shows it can reduce the area accounted for the integrated circuit by a wide margin

並列關鍵字

802.11x ； viterbi ； decoder

參考文獻

[1] IEEE Std.802.11, “Wireless LAN Medium Access Control (MAC) and Physical Layer(PHY) Specification”, June 1997.

[6] A. J. Viterbi, “Error bounds for convolution codes and an asymptotically optimum decoding algorithm,” IEEE Trans. Inform. Theory, vol. IT-13, Apr 1967, pp.260-269.

[7] G. D. Forney, “The Viterbi algorithm,” Proc. IEEE, vol. 61, Mar.1973,pp.268-278,

[8] P. H. Kelly and P. M. Chau, “A flexible constraint length, foldable Viterbi decoder,” Global Telecommunications Conference 1993, vol.1, 29 Nov-2 Dec.1993. pp.631- 635.

[9] G. Fettweis and H. Meyr, “Paralled Viterbi algorithm implementation: Breaking the ACS-bottleneck”, IEEE Trans. Commun,vol.37,Aug 1989,pp.785 – 790,