Quasi-Orthogonal Chirp Signals Design for Multi-User CSS System

Reducing the multiple access interference is a challenge to Multi-user CSS (Chirp Spread Spectrum) communication system. Based on binary chirp signals in multi-user system, a better method to reduce the multi-user interference and improve the system performance is proposed. Two principles of choosing the quasi-orthogonal chirp signals were deduced, (1)Time Bandwidth Product T_mB_w >=20, their cross-correlation is less than 0.2 and it is so little that the signals can be seen as quasi-orthogonal chirp signals (2) Cross-correlation ¿<=0.4, the system Bit Error Rate changed a little. Through theory analysis and computer simulation, 4 slots multi-user chirp signals for WLAN communication systems were obtained, which have a good performance in reducing multiple access interference.