雙多進(jìn)制正交擴(kuò)頻系統(tǒng)的比特軟值輸出算法
Bit Soft-Output Algorithm for Dual N-ary Orthogonal Spread Spectrum System
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摘要: 該文針對雙多進(jìn)制正交擴(kuò)頻與Turbo碼的聯(lián)合系統(tǒng)，基于最大后驗(yàn)概率(MAP)準(zhǔn)則，提出了雙多進(jìn)制正交擴(kuò)頻輸出比特軟值的MAP算法，并給出了簡化MAP算法；同時(shí)，對算法的定點(diǎn)和浮點(diǎn)性能進(jìn)行了仿真，且與現(xiàn)有的軟值算法進(jìn)行了比較。結(jié)果表明，MAP算法能使整個(gè)系統(tǒng)獲得相當(dāng)?shù)脑鲆妫琇=3 的簡化MAP算法在基本不增加復(fù)雜度情況下好于現(xiàn)有的雙最大值算法約0.4dB。
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關(guān)鍵詞:
- Turbo碼;正交碼;最大后驗(yàn)概率算法
Abstract: Focusing on Turbo-coded dual N-ary orthogonal spread spectrum system, this paper proposes an algorithm for computing bit soft metric based on Maximum a Posteriori Probability (MAP) criterion, and then presents a simplified MAP algorithm. Meanwhile, the fixed-point and float-point performances are simulated and compared with several existing algorithms. It is shown that MAP algorithm greatly improves the whole system performance; the simplified MAP algorithm with L=3 outperforms the dual-maxima algorithms 0.4dB without extra cost in complexity.. -
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