基于分组格雷编码的OFDM 雷达通信一体化系统峰均功率比抑制

基于OFDM 共享信号的雷达通信一体化系统具有较高的峰均功率比，由于编码率的限制，采用格雷序列编码抑制系统峰均功率比(PAPR)的算法只适合应用于子载波数较少的场合。针对子载波数较多的系统，该文提出一种利用分组并行格雷编码结合系数加权优化的PAPR 抑制算法，通过将输入比特流分为若干组并行比特，分别进行格雷序列编码、数据符号调制以及逆傅里叶变换，将结果合并就可以得到一个OFDM 符号。在合并之前对每一组引入若干加权系数，这样就构成了多个可供选择的OFDM 符号，通过选择具有最小PAPR 值的OFDM 符号作为发射信号，实现系统PAPR 抑制。最后，仿真了3 种不同分组方案下PAPR 抑制能力、通信误码率以及雷达宽带模糊函数，仿真结果表明，该算法可有效抑制系统PAPR，降低系统误码率，其雷达宽带模糊函数仍为近似图钉型，具有良好的距离和速度分辨能力以及测距、测速精度。 

Peak-to-Average Power Ratio Reduction for Integration of Radar and Communication Systems Based on OFDM Signals with Block Golay Coding

Integration of radar and communication systems based on OFDM signals results in large Peak-to-Average Power Ratio (PAPR). Limited by the code rate, algorithm that use the Golay sequence code to restrain PAPR can only be applied under the condition of a few subcarriers. This study proposes an algorithm to restrain the PAPR of systems with a large number of subcarriers. The algorithm combines the group parallel code with the optimization of weight coefficients. First, bit streams are divided into several groups of parallel bits. Next, every group proceeds with Golay sequence coding, data symbol modulating and inverse Fourier transform. Finally, the parallel result is combined with an OFDM symbol. Before the parallel data are combined, several weight coefficients for every group are introduced; thus, the system has several candidate symbols for transmitting. Then the symbol with minimum PAPR is then selected as the transmitting signal, and the PAPR of the whole system is reduced. PAPR performance, Bit Error Radio (BER) and wideband ambiguity function of three block methods with different coding rate are also simulated. The simulations show that the PAPR of the system decreases and the BER performance improves significantly. The signal exhibits a thumbtack ambiguity function, which suggests good resolution and accuracy for distance and velocity measurements.