采用m-W复合序列的直扩系统规避窄带干扰的研究

Using m-Walsh composite sequences to reduce narrow-band interference in direct sequence spread spectrum systems

针对直接序列扩频系统中窄带干扰抑制的问题,提出了利用m-Walsh(m-W)复合序列规避窄带干扰的方法.该方法根据m-W复合序列的直扩-跳频(DS-FH)特性,通过改变m、Walsh序列的周期和Walsh函数序列的序数控制信号能量主瓣在频域的位置和带宽来避开已知的单频干扰和部分频带干扰,使受干扰的信号能量较少,在抑制窄带干扰的同时,使信号损失最小.仿真结果表明,在未经过频域陷波前,m-W复合序列的误比特率可比常规的m序列降低3～4个数量级;在经过频域陷波后,在相同误比特率时,信噪比可降低0.5～1dB.

Narrow-band interference suppression is a problem in direct sequence spread spectrum （DSSS） systems. The authors developed a method which uses m-Walsh composite sequences to reduce narrow-band interference. Based on the spectrum features of direct sequence-frequency hopping （DS-FH） about the m-Walsh composite se- quence, the position and bandwidth of the main lobe of signal energy in the frequency domain can be controlled by changing the sequence period of m, Walsh functions and the sequence number of the Walsh function. This method loses little energy when canceling and suppressing interference, as itavoids some measured single-frequency interference as well as some types of narrow-band interference. Simulation results showed that the bit-error rate of an m-Walsh com- posite sequence decreased 3 -4 levels than a common m-sequence before trap in the frequency domain. In addition, the anti-jamming capability after trap improved 0.5 to 1 dB compared to suppression using the transform m sequence.