The minimum mean square error-successive interference cancellation( MMSE-SIC) multiuser detection algorithm has high complexity and long processing latency. A multiuser detection algorithm is proposed for multi-beam satellite systems in order to decrease the complexity and latency. The spot beams are grouped base on the distance between them in the proposed algorithm. Some groups are detected in parallel after a crucial group-wise interference cancellation. Furthermore, the multi-stage structure is introduced to improve the performance. Simulation results show that the proposed algorithm can achieve better performance with less complexity compared with the existing group detection algorithm. Moreover,the proposed algorithm using one stage can reduce the complexity over the fast MMSE-SIC and existing group detection algorithm by 9% and20. 9%. The processing latency is reduced significantly compared with the MMSE-SIC.
针对BCH-LDPC级联编码的MIMO系统,提出一种外码译码反馈联合迭代检测译码算法。该算法在迭代检测译码结构的基础上,引入外码硬判决译码反馈。MIMO检测器利用反馈的硬判决信息,经过映射处理后用于更新检测器的检测列表,以减小迭代检测译码算法的运算量。同时,利用外码译码结果直接计算部分LDPC码译码初始信息,提高软信息的可靠性,从而提高系统性能。仿真结果表明,与迭代检测译码算法相比,所提算法能够使处理一帧数据时的平均检测次数减少57.1%,从而降低算法运算量。同时由于外码译码反馈的引入,所提算法至少能够获得0.2 d B性能增益。
Aimed at the conventional serial communication system fails when the channel was frequency-selective,long delay and multi-paths effect,resulting in inter-symbol-interference( ISI),an iterative system for underwater acoustic communication( UWAC) was proposed,which employed iterative differential detection and spread spectrum technique. The proposed scheme adopts π /4-DQPSK soft demodulation to overcome the difficulty of phase ambiguity. For suppression of ISI in UWAC,joint demodulation and decoding iteration was used. The communication scheme has the characteristic of long communication range at low SNR,and the maximum range is up to 100 km. The theoretic analysis and simulation results show that the proposed scheme outperforms traditional serial one. When SNR is- 6 dB,after four joint iterations,compared with serial scheme,BER can decrease from 10- 2to 10- 5.
针对格基约减辅助的THP(LRA-THP)算法运算复杂度高问题,在一种分组预编码算法的基础上,提出一种适用于多波束卫星系统的低复杂度分组预编码算法,该算法根据波束间的距离对用户进行分组,通过最大化SSLNR得到预处理矩阵,抑制组间干扰,各组内采用LRA-THP算法,计算预处理矩阵时充分利用多波束卫星信道的特点,降低需要求解的预处理矩阵的维度,从而减小算法的运算复杂度.理论及仿真分析结果显示,该算法的运算量远低于LRA-THP,与原分组预编码算法相比,该算法的复杂度能够降低24%,同时性能损失不超过0.1 d B.另外,该算法中引入一组参数,使其能够灵活地在复杂度与可靠性之间进行折中.
An iterative detection and decoding algorithm with outer code decision feedback is proposed for the dual polarized( DP) land mobile satellite( LMS) MIMO systems using concatenated codes. A feedback structure is added after the outer decoder in the proposed algorithm. The feedback information is exploited to control the detecting list in the MIMO detector and reduce the number of symbols which have to be processed at each iteration. As a result,the computational complexity is reduced. Meanwhile,the successfully decoded outer code words are used to calculate the more reliable initial information for the inner decoder and the system performance can be improved by this step. The simulation results show that the proposed algorithm can reduce the computational complexity compared to the traditional iterative detection and decoding algorithm and achieve better performance.
