共查询到19条相似文献,搜索用时 187 毫秒
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球形译码的半径对译码的复杂度有很大的影响。文章在卡方分布特性的基础上设计了一种基于统计裁剪的改进球形译码算法,该算法通过减去估算出来的未检测层的半径的大小,达到对当前检测层的半径进行缩减的目的;同时综合考虑了信道的影响,对均方误差较大的列进行ML检测,剩余信号进行树裁剪的SD算法。仿真表明,该算法大大降低了球形译码的算法复杂度。 相似文献
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稀疏码分多址(SCMA)系统中基于球形译码算法(SD)由于具有优良的性能受到越来越多的关注,然而现有基于SD的算法只能用于某些特定星座结构的检测,导致其应用受限.该文提出一种适用于任意星座且性能达到最大似然(ML)算法性能的改进球形译码(ISD)算法.该算法将用户星座图拆分,并将用户星座图转换为多层树结构,利用对树结构的搜索完成译码操作,并且对树的搜索是从高层向低层进行的.因此,可以将SCMA检测转换成最小化树结构部分度量问题;同时,所提出的改进算法对星座图的结构无任何限制,所以该算法适用于任意类型的星座图.此外,由于SCMA的稀疏性,每一层的部分度量均与分配给每个资源元素的用户无关,从而进一步降低了计算复杂度. 相似文献
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球形译码是多输入多输出(MIMO)系统中一种高效的检测算法。但对于非确定性MIMO系统,已有球形译码算法不能同时获得最优解和最低搜索树。针对该问题,提出了一种高效球形译码检测算法,通过增加常量对最大似然代价函数进行等价转化,使得球形译码算法获得最优解的同时具有最低搜索树,大大降低了球形译码算法中的搜索复杂度。仿真结果表明,对于高阶正交幅度调制(M-QAM,M>4)方式,本文算法优于修正的CT(Modified Cui and Tellambura,MCT)算法,大大提高了球形译码中的搜索效率。此外,仿真结果给出了最小复杂度下的最优参数值。 相似文献
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球形译码算法的检测性能最接近最大似然检测算法,但其计算复杂度仍然较高。为了在计算复杂度和系统性能之间取得良好折中,在研究标准球形译码的基础上,提出一种新的球形译码改进算法。新算法由快速球形译码与基于MMSE准则的SQRD算法构成。该算法在高信噪比时采用SQRD算法,低信噪比时采用KSDA算法。仿真结果表明,该算法在降低球形译码算法复杂度的同时获得了较好的系统性能。 相似文献
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现有的空间调制系统球形译码(Sphere-Decoding,SD)检测算法虽然能够较大地降低最大似然(Maximum-Likelihood,ML)检测算法的计算复杂度,但由于其更新半径比较松散、收敛较慢,计算复杂度降低的水平仍十分有限,尤其是在高阶调制系统下.针对上述问题,采用统计分布的思想对现有算法更新半径中的冗余项进行估计,提出了两种改进的球形译码检测算法.理论分析与仿真结果表明,改进算法在达到最优检测性能的同时,极大地降低了传统球形译码的计算复杂度,具有较好的理论和实际应用意义. 相似文献
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It is well known that one of the main drawbacks of orthogonal frequency division multiplexing (OFDM) is the potentially high peak-to-average power ratio (PAPR) of the (OFDM) signal. Partial transmit sequence (PTS) is a widely accepted method in reducing PAPR of OFDM signal. As traditional optimal PTS (OPTS) technique requires an exhaustive search over all the combinations of the allowed phase factors the search complexity increases exponentially with the number of sub-blocks. In this paper, a new precalculated radius sphere decoding (PRSD) is presented. It can achieve the same PAPR performance but at lower computational complexity compared with OPTS and existing sphere decoding (SD) approach at zero decoding failure rate. 相似文献
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针对传统BP译码算法需要初始条件的缺点,本文提出了一种基于软输入软输出(SISO)的LDPC码盲译码算法,所提算法采用类似BP迭代译码算法步骤,通过对距离信息进行迭代处理,实现无需接收信号的信噪比和信道状态即可译码;同时,还将所提盲译码算法推广到多进制LDPC码的译码应用中。本文所提盲译码算法在初始状态难以确定以及接收信号信噪比难以估计的通信信道中具有重要价值。仿真结果表明,所提算法不论是在AWGN信道还是在瑞利衰落信道上都能取得优良的性能,不论是与标准BP译码算法还是与分层BP译码算法相比,在性能相近的情况下,计算复杂度都有所降低。 相似文献
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It is well known that maximum-likelihood (ML) decoding in many digital communication schemes reduces to solving an integer least-squares problem, which is NP hard in the worst-case. On the other hand, it has recently been shown that, over a wide range of dimensions N and signal-to-noise ratios (SNRs), the sphere decoding algorithm can be used to find the exact ML solution with an expected complexity that is often less than N3. However, the computational complexity of sphere decoding becomes prohibitive if the SNR is too low and/or if the dimension of the problem is too large. In this paper, we target these two regimes and attempt to find faster algorithms by pruning the search tree beyond what is done in the standard sphere decoding algorithm. The search tree is pruned by computing lower bounds on the optimal value of the objective function as the algorithm proceeds to descend down the search tree. We observe a tradeoff between the computational complexity required to compute a lower bound and the size of the pruned tree: the more effort we spend in computing a tight lower bound, the more branches that can be eliminated in the tree. Using ideas from semidefinite program (SDP)-duality theory and Hinfin estimation theory, we propose general frameworks for computing lower bounds on integer least-squares problems. We propose two families of algorithms, one that is appropriate for large problem dimensions and binary modulation, and the other that is appropriate for moderate-size dimensions yet high-order constellations. We then show how in each case these bounds can be efficiently incorporated in the sphere decoding algorithm, often resulting in significant improvement of the expected complexity of solving the ML decoding problem, while maintaining the exact ML-performance. 相似文献
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In this letter, we propose an extension of the probabilistic tree pruning sphere decoding (PTP-SD) algorithm that provides further improvement of the computational complexity with minimal extra cost and negligible performance penalty. In contrast to the PTP-SD that considers the tightening of necessary conditions in the sphere search using per-layer radius adjustment, the proposed method focuses on the sphere radius control strategy when a candidate lattice point is found. For this purpose, the dynamic radius update strategy depending on the lattice point found as well as the lattice independent radius selection scheme are jointly exploited. As a result, while maintaining the effectiveness of the PTP-SD, further reduction of the computational complexity, in particular for high SNR regime, can be achieved. From simulations in multiple-input and multiple-output (MIMO) channels, it is shown that the proposed method provides a considerable improvement in complexity with near-ML performance. 相似文献
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一种低复杂度的差分酉空时调制多符号球形译码算法 总被引:1,自引:0,他引:1
该文提出了一种瑞利衰落信道下差分酉空时调制系统中多符号差分球形译码的改进算法。该算法在执行球形译码的最大似然度量搜索时,仅对具有较小最大似然度量的部分测试符号进行搜索,从而大大减少了搜索的次数,同时提出了一种逐项进行的最大似然度量计算方法,可以尽早发现超过搜索范围的测试符号并终止计算,在避免无谓的运算负担的同时得到所需的具有较小最大似然度量的部分测试符号。仿真表明,在适中的信噪比范围内,该算法在牺牲少量系统性能的基础上降低了超过50%的运算量。 相似文献
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一种新的多天线系统中的快速广义球形解码算法 总被引:1,自引:0,他引:1
该文提出了一种新的广义球形解码算法.与常规球形解码算法相比,它能够处理多输入多输出系统(MIMO)中发送天线M多于接收天线N的情形,并且其解码速度远大于已有的广义球形解码算法.其基本思想是将M维的传输信号矢量分成N-1和M-N+1维的子矢量xa和xb,通过一些简单地变换,就可以使用一个常规球形解码器来选取合适的xb,然后再利用另一个常规球形解码器来获得xa,从而得到整个传输信号矢量.仿真结果表明,这种新的快速广义球形解码算法(命名为双层球形解码算法)比现有的广义球形解码算法具有更低的复杂度. 相似文献
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In this article, a new system model for sphere decoding (SD) algorithm is introduced. For the 2 × 2 multipleinput multiple-out (MIMO) system, a simplified maximum likelihood (SML) decoding algorithm is proposed based on the new model. The SML algorithm achieves optimal maximum likelihood (ML) performance, and drastically reduces the complexity as compared to the conventional SD algorithm. The improved algorithm is presented by combining the sphere decoding algorithm based on Schnorr-Euchner strategy (SE-SD) with the SML algorithm when the number of transmit antennas exceeds 2. Compared to conventional SD, the proposed algorithm has low complexity especially at low signal to noise ratio (SNR). It is shown by simulation that the proposed algorithm has performance very close to conventional SD. 相似文献