高階QAM調(diào)制下基于對(duì)數(shù)似然比門(mén)限的自適應(yīng)解調(diào)方案

雷維嘉; 宋海娜; 謝顯中

doi:10.11999/JEIT160821

高階QAM調(diào)制下基于對(duì)數(shù)似然比門(mén)限的自適應(yīng)解調(diào)方案

doi: 10.11999/JEIT160821

基金項(xiàng)目:

國(guó)家自然科學(xué)基金(61471076)，重慶市基礎(chǔ)與前沿研究計(jì)劃(cstc2015jcyjA40047)，長(zhǎng)江學(xué)者和創(chuàng)新團(tuán)隊(duì)發(fā)展計(jì)劃(IRT1299)，重慶市科委重點(diǎn)實(shí)驗(yàn)室專項(xiàng)經(jīng)費(fèi)(CSTC)

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- 文章訪問(wèn)數(shù): 1886
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出版歷程
- 收稿日期: 2016-08-03
- 修回日期: 2017-01-09
- 刊出日期: 2017-06-19

Adaptive Demodulation Scheme of High Order QAM Based on Log-likelihood Ratio Threshold

Funds:

The National Natual Science Foundation of China (61471076), The Chongqing Research Program of Basic Research and Frontier Technology (cstc2015jcyjA40047), The Program for Changjiang Scholars and Innovative Research Team in University (IRT1299), The Special Fund of Chongqing Key Laboratory (CSTC)

摘要

摘要: 現(xiàn)有的自適應(yīng)解調(diào)方案中采用的調(diào)制星座階數(shù)最高僅限于16，且方案分析和設(shè)計(jì)中沒(méi)有考慮信道編碼的譯碼環(huán)節(jié)。該文研究適用于高階QAM調(diào)制的自適應(yīng)解調(diào)算法，并結(jié)合無(wú)率糾錯(cuò)碼提出一種收端速率自適應(yīng)方案。收端將符號(hào)中每個(gè)比特的對(duì)數(shù)似然比絕對(duì)值與設(shè)定的解調(diào)門(mén)限值比較，大于該解調(diào)門(mén)限值的比特解調(diào)，否則刪除。無(wú)率碼譯碼碼字長(zhǎng)度固定，通過(guò)調(diào)整解調(diào)門(mén)限達(dá)到誤碼性能要求。在解調(diào)比特的平均互信息分析的基礎(chǔ)上，給出不同信噪比下達(dá)到期望的譯碼誤碼性能要求的解調(diào)門(mén)限值及解調(diào)比例的計(jì)算方法。以256-QAM星座和Raptor碼為例給出方案設(shè)計(jì)實(shí)例并進(jìn)行仿真，仿真結(jié)果驗(yàn)證了理論分析的正確性和方案的有效性。
- 自適應(yīng)解調(diào) /
- 正交幅度調(diào)制 /
- 速率自適應(yīng) /
- 對(duì)數(shù)似然比 /
- 互信息 /
- 無(wú)率編碼
Abstract: The order of the modulation used in existing adaptive demodulation schemes is no higher than 16, and the decoding of channel codes is not taken into consideration in the analysis and design. In this paper, an adaptive demodulation algorithm used for higher order Quadrature Amplitude Modulation (QAM) is studied. A rate adaptive scheme at receiver is proposed which combines this algorithm and rateless error correcting codes. The bits in received symbols with absolute log-likelihood ratio value higher than demodulation threshold are demodulated, otherwise, deleted. In the scheme, the length of the codeword for the rateless codes decoding is fixed, and error performance is achieved by adjusting the demodulation threshold. Based on the analysis of the average mutual information of the demodulation bits, the calculation method is given of the log-likelihood ratio demodulation threshold and demodulation bits ratio under different signal-to-noise ratio. A sample design scheme employing 256-QAM constellations and Raptor codes is provided, and the simulation results of this sample are consistent well with those of the theoretical analysis, which confirms the effectiveness of the scheme.
- Adaptive demodulation /
- Quadrature Amplitude Modulation (QAM) /
- Rate adaptive /
- Log-likelihood ratio /
- Mutual information /
- Rateless codes

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參考文獻(xiàn)(13)

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