宽带高速车载环境中的分布式空时频编码

摘要

利用高速车载终端与基站宽带通信时信道的多径时变特性,提出一种分布式空时频编码方法.该方法通过选择车内空闲终端构成虚拟天线阵列进行协同编码,在不降低传输速率的前提下,能够获得信道中潜在的协同分集、时间分集和频率分集增益.理论分析表明:车载速度的提高使时间分集增益得以增强,正确解码中继个数的增加使协同分集增益得以增加.仿真实验验证了理论分析的正确性,结果证实了在较高信噪比下分布式空时频编码较分布式空频编码有更好的误比特性能.最后,给出了两种编码在实际应用中的切换信噪比.%In order to exploits the characteristic of multi-path and time varying of broadband communications channel between high-speed vehicular terminal and base station, a distributed space-time-frequency code scheme is proposed. In this scheme the distributed space-time-frequency code is implemented by a visual transmitter antennas arrays constructed from several idly terminals around the source node. So the scheme can acquire full inherent diversity gains including time diversity gain, frequency diversity gain, and cooperative diversity in channel without the information transmission rate loss. Theoretical analysis shows that time diversity gain increases as vehicle speed increasing, and the cooperative diversity gain is improved as the number of decodable relay nodes increasing. The simulation experiments validate theoretical analysis and indicate that the proposed scheme has better BER performance than distributed space-frequency code at higher SNR value. The simulation experiments also give the switch SNR between the two codes scheme (DSTFC and DSFC) in practice.