Limited feedback unitary precoding for orthogonal space-time block codes
Limited feedback unitary precoding for orthogonal space-time block codes
复制标题
DOI：
10.1109/tsp.2004.838928
复制
发表时间：
2005-01-01
影响因子：
5.4
通讯作者：
Heath, RW
中科院分区：
文献类型：
--
作者：
Love, DJ;Heath, RW
正交空时分组码（ostbc）是一类在瑞利衰落信道中实现全分集的易译码的空时码。ostbc仅适用于特定数量的发射天线，并且不像利用发射信道信息的分集技术那样提供阵列增益。当信道状态信息在发射机可用时，可以使用空时码字预编码来支持不同数量的发射天线并提高阵列增益。不幸的是，许多无线系统中的发射机不知道当前的信道条件。这激发了有限反馈预编码方法，如信道量化或天线子集选择。本文研究了一种有限反馈方法，该方法使用发送端和接收端先验已知的预编码矩阵的码本。接收机根据当前信道条件从码本中选择一个矩阵，并通过无差错、零延迟的反馈将最优码本矩阵传递给发射机。通道。提出了在码本中选择最优预编码矩阵的准则，该准则直接关系到预编码系统中符号错误概率的最小化。基于最优码字选择准则，推导出低平均失真码本。所得到的设计与著名的应用数学问题格拉斯曼流形中的子空间填充有关。用这种方法设计的码本在瑞利衰落信道中具有完全的分集顺序。蒙特卡罗仿真表明，有限反馈预编码优于天线子集选择。
Orthogonal space-time block codes (OSTBCs) are a class of easily decoded space-time codes that achieve full diversity order in Rayleigh fading channels. OSTBCs exist only for certain numbers of transmit antennas and do not provide array gain like diversity techniques that exploit transmit channel information. When channel state information is available at the transmitter, though, precoding the space-time codeword can be used to support different numbers of transmit antennas and to improve array gain. Unfortunately, transmitters in many wireless systems have no knowledge about current channel conditions. This motivates limited feedback precoding methods such as channel quantization or antenna subset selection. This paper investigates a limited feedback approach that uses a codebook of precoding matrices known a priori to both the transmitter and receiver. The receiver chooses a matrix from the codebook based on current channel conditions and conveys the optimal codebook matrix to the transmitter over an error-free, zero-delay feedback. channel. A criterion for choosing the optimal precoding matrix in the codebook is proposed that relates directly to minimizing the probability of symbol error of the precoded system. Low average distortion codebooks are derived based on the optimal codeword selection criterion. The resulting design is found to relate to the famous applied mathematics problem of subspace packing in the Grassmann manifold. Codebooks designed by this method are proven to provide full diversity order in Rayleigh fading channels. Monte Carlo simulations show that limited feedback precoding performs better than antenna subset selection.