System based Code Evaluation Criteria for CDM Applications in Sensor and Data Transmission Systems

To increase the multiplexing capability of code-division m ultiplexing (CDM) applied in optical sensor networks, a system based code evaluation is required. This cont ribution analyses evaluation criteria for sequences applied in CDM systems. A comparison of an optical sensor app lication and a single user data transmission system is presented. While a detection signal-to-noise rat io and the bit error rate are used to evaluate data transmission systems, the proposed optical sensor applica tion uses a modified signal-to-multiuser-interference ratio (mSMUI). The main difference exists in the handling of interference. In contrary to data transmission, the mSMUI requires a separation of positive and negative int erferences. Both applications are simulated for different binary sequences. While the Legendre sequence wi th a length of 503 chips achieves the over all best results for the optical sensor application, the single user data transmission simulation shows no significant sequence influence.