Design of spreading sequences using a modified bridging method

The performance of a code division multiple access system depends on the correlation properties of the employed spreading code. An auto-correlation function with a distinct peak enables proper synchronization and suppresses intersymbol interference. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference. However, these requirements contradict each other and a trade-off needs to be established. In this paper, a modified bridging method is proposed to minimize cross-correlation with auto-correlation being allowed to lie within a fixed region. This approach is applied to the design of complex spreading sequences.