Space-time codes for high data rate wireless communication: performance criteria in the presence of channel estimation errors, mobility, and multiple paths
Space-time codes for high data rate wireless communication: performance criteria in the presence of channel estimation errors, mobility, and multiple paths
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DOI：
10.1109/26.752125
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发表时间：
1999-02
期刊：
影响因子：
--
通讯作者：
V. Tarokh;A. Naguib;N. Seshadri;A. Calderbank
中科院分区：
文献类型：
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作者：
V. Tarokh;A. Naguib;N. Seshadri;A. Calderbank
空时编码是一种在衰落信道上实现多发射天线优点的带宽和功率高效的通信方法。已经使用针对准静态平坦瑞利或莱斯衰落导出的设计标准来构造特定的码，其中在接收器处可以获得信道状态信息。显然，在没有理想的信道状态信息的情况下，如果所导出的设计准则仍然有效，则空时码的实用性将大大增强。更可取的是，设计标准不能对频率选择性和多普勒扩展过度敏感。本文从信道估计误差的影响入手，对这些问题进行了理论研究。这里假设信道估计器在接收端提取衰落系数，并且对于恒定能量的星座，证明了在没有理想的信道状态信息的情况下，空时码的设计准则仍然有效。分析还表明，只要发射天线的数量很少，标准的信道估计技术就可以与空时编码结合使用。我们还推导了在存在信道估计误差的情况下的最大似然检测度量。其次，研究了缓变瑞利信道下多径对空时码性能的影响。证明了多条路径的存在不会降低用于构造空时码的设计准则所保证的分集阶数。类似的结果也适用于具有或不具有多条路径的快速衰落信道。得出的结论是，在各种移动条件和环境影响下，都能达到空时编码所承诺的分集阶数。
Space-time coding is a bandwidth and power efficient method of communication over fading channels that realizes the benefits of multiple transmit antennas. Specific codes have been constructed using design criteria derived for quasi-static flat Rayleigh or Rician fading, where channel state information is available at the receiver. It is evident that the practicality of space-time codes will be greatly enhanced if the derived design criteria remain valid in the absence of perfect channel state information. It is even more desirable that the design criteria not be unduly sensitive to frequency selectivity and to the Doppler spread. This paper presents a theoretical study of these issues beginning with the effect of channel estimation error. Here it is assumed that a channel estimator extracts fade coefficients at the receiver and for constellations with constant energy, it is proved that in the absence of ideal channel state information the design criteria for space-time codes is still valid. The analysis also demonstrates that standard channel estimation techniques can be used in conjunction with space-time codes provided that the number of transmit antennas is small. We also derive the maximum-likelihood detection metric in the presence of channel estimation errors. Next, the effect of multiple paths on the performance of space-time codes is studied for a slowly changing Rayleigh channel. It is proved that the presence of multiple paths does not decrease the diversity order guaranteed by the design criteria used to construct the space-time codes. Similar results hold for rapid fading channels with or without multiple paths. The conclusion is that the diversity order promised by space-time coding is achieved under a variety of mobility conditions and environmental effects.