基于多种调制方式的超宽带空时网格编码

Space-Time Trellis Coding for UWB Systems Based on Different Modulations

为结合多入多出系统和超宽带的优点来实现高速高效的传输，将空时编码技术应用于超宽带系统中，讨论了基于脉冲位置调制（PPM：Pulse-Position Modulation）、脉冲幅度调制（PAM：Pulse-Amplitude Modulation）以及双正交调制3种不同方式的超宽带空时网格编码方案。考虑在发送和接收端已知信道状态信息，分别建立了3种方案的发射接收模型。仿真结果表明，在高斯信道和IEEE802．15．3a信道条件下，采用PPM的超宽带空时网格编码方案的性能都远优于其他两种方案，当信噪比为8dB时，误码率降低10～100倍。进一步考虑在存在多用户干扰条件下，该系统性能随用户数的增加而下降。

To exploit the advantages of both UWB （Ultra-WideBand） and MIMO （ Multiple-Input Multiple-Out- put）, STrC （Space-Time Trellis Codes） is applied to UWB systems, and STrC-UWB systems with different modulations are discussed. Models of three schemes employing PPM （ Pulse-Position Modulation）, PAM （ Pulse- Amplitude Modulation） and biorthogonal modulation are set up separately, and it is assumed that the channel state information can be obtained at both transmitter and receiver. Simulation results show STrC-UWB with PPM can achieve much better performance than the others under both Gaussian and IEEE802. 15.3a channel. The bit error rate of STIE-UWB with PPM is 10 - 100 times lower than the other two while the signal to noise ratio is 8 dB. So the scheme employing PPM is preferred and we further find when MUI （ Multi-User Interference） is considered the performance degrades when the number of users increases.