大时延卫星通信的随机接入分段前导检测

针对卫星通信场景下具有较大用户传输时延的特点,提出了一种随机接入分段前导检测算法.不同于现有随机接入前导检测算法中仅提取前导序列区间对应接收信号的做法,该算法根据发送信号中前导序列与保护间隔对应的时间区间,分两段提取接收信号,从而分别估计传输时延的小数倍与整数倍部分.此外,设计了峰值二次有效性评估机制,有效解决了整数倍时延估计过程中小数倍时延带来的伪峰问题.最后,推导了虚警概率与相关门限关系的闭式表达式以确定最小相关门限值.仿真结果表明,所提算法能够在大时延环境下对时延进行准确估计,并且极大节省了前导根序列和时间资源开销,适用于卫星通信随机接入场景.

Segmented preamble detection of random access in satellite communication with large delay

According to the characteristics of large transmission delay in satellite communication scenarios,a random access sequence detection algorithm is proposed by segmenting the received signal.Different from the existing random access sequence detection algorithm that only extracts the received signal corresponding to the preamble sequence interval,this algorithm extracts the received signal in two segments which correspond to the preamble sequence and the guard interval of the transmitted signal,and separately estimates the fractional and integral transmission delay.In addition,a peak secondary effectiveness evaluation mechanism is designed,which effectively solves the false peak problem caused by the fractional delay in the integer multiple delay estimation process.Finally,the closed-form expression of the relationship between the false alarm probability and the correlation threshold is derived to determine the minimum correlation threshold.The simulation results show that the proposed algorithm can accurately estimate the delay in a large delay environment,and greatly save the overhead lead of root sequence and time resource.So it is suitable for random access in satellite communication scenarios.