Fast Acquisition Algorithm for PN Sequences

在CDMA移动通信中，采集程序是在建立连接之前要完成的第一个也是最基本的功能。而过程的加速是减少通信开销的重要问题之一。本研究的目的是利用PN序列的内部复合结构，提出一种新的PN序列（如m序列、gmw序列等）的采集算法，并证明该算法能够提供比传统算法更快更好的采集性能。在2004财政年度，我们将先前假设芯片同步的基本算法扩展到实际可行的快速算法，不需要芯片同步，并检查了其基本特性。通过对平均采集时间及其方差的理论分析，我们可以证明该算法与传统方法相比具有足够好的性能。在2005财政年度，通过计算机模拟对上一年提出的快速采集算法进行了详细的检验，该算法在加入了时效函数之后。我们还比较了该算法与传统算法的计算复杂度。结果表明，所提出的快速采集算法在平均采集时间和方差方面具有较好的性能，且计算复杂度的增加很小。

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.