Cyclic extended spread coded multicarrier CDMA/TDD transmission scheme for wireless broadband multimedia communications

This paper proposes two multicarrier CDMA/TDD (code division multiple access/time division duplex) systems based on cyclic extension techniques of spread code and information data frame. By using cyclic extension techniques, it is very easy to find not only the code synchronization point but also the FFT start point which must be decided at the receiver of multicarrier CDMA system. In addition, we exploit modified cyclic shifted and extended codes generated from one normal PN code, e.g. M or Gold sequence. Therefore our proposed system can realize high code utilization efficiency in comparison with conventional system. In this paper, moreover, using cyclic shifted codes of M and Gold sequences and the proposed cyclic extension techniques, the bit error rate performance of the proposed system under the multipath environment is evaluated by computer simulations.