Kazuo Mori

PAPR Reduction Method for OFDM Signal by Using Dummy Sub-carriers

One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) in its time domain signal. The larger PAPR signal would course the fatal degradation of bit error rate performance (BER) due to the inter-modulation noise in the non-linear channel. This paper proposes an improved DSI (Dummy Sequence Insertion) method, which can achieve the better PAPR and BER performances. The feature of proposed method is to optimize the phase of each dummy sub-carrier so as to reduce the PAPR performance by changing all predetermined phase coefficients in the time domain signal, which is calculated for data sub-carriers and dummy sub-carriers separately. To achieve the better PAPR performance, this paper also proposes to employ the time-frequency domain swapping algorithm for fine adjustment of phase coefficient of the dummy subcarriers, which can achieve the less complexity of processing and achieves the better PAPR and BER performances than those for the conventional DSI method. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional methods in the non-linear channel.

Dynamic Subband and Code Channel Assignment for Multicast Band Division MC-CDMA Systems

This paper proposes a dynamic frequency subband and code channel assignment method for multicast band division multicarrier CDMA systems. The proposed method introduces multiple channel multicast transmissions, where the multicast transmission is divided into two channels; one is for all users in the multicast group, and the other is for a part of the multicast users. The base stations individually assign the frequency subbands and code channels to these two multicast channels. The optimum and suboptimum solutions are proposed for the two-layered frequency subband and code channel assignment. The evaluation results show that the proposed method has superior throughput performance to the single channel multicast systems