Orthogonal codes performance in multi-code CDMA

In future wireless networks such as wireless LANs, third generation cellular mobile systems (3G), and PCS different rate and quality of service (QOS) requirements must be accommodated. A mobile terminal may set up and modify sessions for voice, data, image, as well as video through wireless connections to the base station. Multi-Code CDMA (MC-CDMA) is a technique that provides variable rate services with different quality requirements by assigning multiple codes (on demand) and thus increasing capacity to users. The system retains the CDMA advantage in combating multipath and does not require significant modifications of the radio frequency (RF) circuitry. It can evolve from commercial digital cellular systems based on IS-95. In this research, we study Multi-Code CDMA using orthogonal Gold code and Walsh code for modulation. We study the performance of the system by measuring Bit Error Rate (BER) with different channel characteristics and different number of users. The results show that the Gold code performs better in terms of low BER because of high auto-correlation and low cross-correlation of Gold code.