Concatenated sequences for inter-base station synchronization in WCDMA TDD mode

In order to prevent inter-slot interference and to enhance system capacity in wideband code division multiple access (WCDMA) time division duplex (TDD) mode, synchronization between the base stations are necessary. The easiest way of achieving synchronization is using the global positioning system (GPS). However the use of the GPS would increase the costs of base-stations, as special radio receivers are required to detect the time reference signals. An alternative solution that is proposed by 3GPP is to synchronize the base stations via an air-interface using inter-cell synchronization codes since this would reduce the costs of base stations as only simple hardware is required. We summarize the proposed synchronization codes by 3GPP using concatenated extended complementary (CEC) sequences with multiple code offsets. This is followed by the presentation of a new form of concatenated sequence which has relatively better cross correlation properties than the proposed sequences. Problems and shortcomings regarding the use of this new form of sequences are also addressed.