Abstract
Orthogonal frequency and code division multiplexing (OFCDM) is available as orthogonal frequency and code division multiple access (OFCDMA) by allocating subcarrier to users. OFCDMA is an efficient transmission method assigning the subcarrier and the channel code according to channel state or many different environments. However, OFCDMA is hard to apply many frequency spreading codes when it is compared with OFCDM because of the restrictive subcarriers. This problem leads to decrease the frequency diversity. Therefore we propose system that combines cyclic delay diversity (CDD) with cooperative relaying system based on OFCDMA. This system complements this restrict by spatial diversity. In addition to that, the proposed system obtains diversity gain without loss of the throughput when direct-path condition is not good.
