Reduced search for optimum code sets to reduce PAPR in MC-CDMA system

In this paper, we propose a reduced search algorithm to find optimum Walsh-Hadamard (WH) code sets which can maintain almost the minimum peak to average power ratio (PAPR) in multi-carrier (MC) CDMA system. It was discovered that the PAPR of MC-CDMA system can be reduced by suitably allocating the user codes. The code allocation table must be made before the system operation, in order to dynamically allocate the optimum WH code when a user requests a connection. Searching for the optimum code set for each number of users in connection with the reasonable code set size incurs prohibitive computations even with a small alphabet sized modulation scheme such as BPSK or QPSK. The proposed search algorithm shows a tremendous reduction of computational time to search for optimum code sets.