No abstract

No abstract

No abstract

The present paper proposes a new method for constructing polyphase asymmetric zerocorrelation zone (A-ZCZ) sequence sets using discrete Fourier transform (DFT) matrices and orthogonal codes. The proposed method can generate A-ZCZ sequence sets that cannot be obtained using known methods. The newly obtained A-ZCZ sequence sets include optimal ZCZ sequence sets. In addition, two arbitrary sequences that belong to different sequence subsets become uncorrelated sequences. The proposed method is expected to be usefu1 for reducing or avoiding inter-cell interference from adjacent cells in approximately synchronized code-division multiple-access (AS-CDMA) systems.

No abstract

No abstract

No abstract

In this paper, we propose a construction of periodic complete complementary codes composed of the expanded modulatable orthogonal sequences. Because the number of the expanded moddatable orthogonal sequences of period N 2 is infinite, the number of the periodic complete complementary codes of period N 2 is also infinite. It is already proved that the proposed sequenses are periodic complete complementary codes. In the meantime Suehiro has proposed a signal design method for approximat ery synchronized CDMA systems without co-channel interference. In this signal design method, we can assign the proposed periodic complete complementary codes as code words to each user so that the information transmission rate is increased.In this paper, we propose a general construction of periodic complete complementary codes composed of the expanded modulatable orthogonal sequences. Because the number of the expanded modulatable orhtogonal sequences of period N 2 is infinite, the number of the periodic complete complementary codes composed of the expanded modulatable orthogonal sequences of period N 2 is also infinite. It is already proved that the proposed sequenses are periodic complete complementary codes.In the meantime Suehiro[8] has proposed a signal design method for approximatery synchronized CDMA systems without co-channel interference. In this signal design method, we can assign the proposed periodic complete complementary codes as code words to each user so that the information transmission rate is increased.