Design of variable–weight quadratic congruence code for optical CDMA

A variable–weight code family referred to as variable–weight quadratic congruence code (VWQCC) is constructed by algebraic transformation for incoherent synchronous optical code division multiple access (OCDMA) systems. Compared with quadratic congruence code (QCC), VWQCC doubles the code cardinality and provides the multiple code-sets with variable code–weight. Moreover, the bit-error rate (BER) performance of VWQCC is superior to those of conventional variable–weight codes by removing or padding pulses under the same chip power assumption. The experiment results show that VWQCC can be well applied to the OCDMA with quality of service (QoS) requirements.