准规则LDPC码软扩频方法

Tamed Spread Spectrum Method Based on Quasi-regular LDPC Code

为实现低复杂度条件下的长码软扩频,提出了一种基于准规则低密度奇偶校验码(QR-LDPC)的软扩频方法.利用编码度优化的方法构造了一种QR-LDPC.提出了一种基于编码约束的同步方法,降低了长码软扩频系统的同步复杂度.仿真结果表明,基于QR-LDPC的软扩频方法是一种有效、可行的长码软扩频方法,可同时获得较大的扩频增益和编码增益;相同扩频比条件下,系统误码率性能优于传统的直接序列扩频系统.

In order to realize a low complexity tamed spread spectrum system based on long codes, a no- vel tamed spread spectrum system based on quasi-regular low density parity check （QR-LDPC） code was proposed. This system employs a new LDPC code called quasi-regular LDPC which is constructed using degree distribution optimization method. A synchronization algorithm exploits check constraint was pro- posed, and then the complexity of synchronization for long code tamed spread spectrum was reduced. Simulations show that the proposed tamed spread spectrum is an effective and feasible scheme adopt long codes, both spreading gain and coding gain could be achieved. The bit error rate performance of proposed system is also better than traditional direct sequence spread spectrum system since the spread factor is e- qual.