Fast Acquisition Algorithm for PN Sequences

在码分多址移动通信中，捕获过程是建立连接前要完成的第一个也是最基本的功能。本研究的目的是利用m序列、GMW序列等伪随机序列的内部复合结构，提出一种新的伪随机序列捕获算法，并证明该算法比传统的捕获算法具有更快、更好的捕获性能。2004财年，我们将原来假设码片同步的基本算法扩展为一种实际可行的、不需要码片同步的快速算法，并检验了它的基本性质。通过对平均捕获时间及其方差的理论分析，表明该算法与传统的捕获算法相比具有足够好的性能。在2005财年，通过计算机仿真对前一年提出的加入超时函数的快速捕获算法进行了详细的验证。我们还比较了该算法与传统算法的计算复杂度。结果表明，该快速捕获算法在计算复杂度增加不大的情况下，可以在平均捕获时间及其方差方面提供更好的性能。

In CDMA mobile communications, the acquisition procedure is the first and most fundamental function to be done before establishing connection. And the acceleration of the procedure is the one of the most important problems to reduce the communication overhead.The purpose of this research is to propose a new acquisition algorithm for PN sequences, such as m-sequence, GMW-sequence etc., by utilizing their internal composite structures of PN sequences and show that the proposed algorithm can provide faster and better acquisition performance than the conventional algorithms.In the fiscal year 2004, we extended our previous basic algorithm, which assumes chip synchronization, to a realistically feasible fast algorithm, which does not require chip synchronization, and examined its fundamental properties. Through theoretical analyses for the mean acquisition time and its variance, we could show that the proposed algorithm exhibits sufficiently good performance compared to the conventional methods.In the fiscal year 2005, the proposed fast acquisition algorithm in the previous year, after incorporating the time-over function, was examined in detail through computer simulations. We also compared the computational complexity of the proposed algorithm with those of the conventional ones. It is concluded that the proposed fast acquisition algorithm can provide much better performance in mean acquisition time and its variance with a quite small increase of computational complexity.