We propose design criteria for phase sequences in Selected Mapping (SLM): the average and variance of peak-to-average power ratio (PAPR) of the phase sequences themselves. We evaluate the effects of SLM with some phase sequences for reducing the PAPR of multicarrier code division multiple access (MC-CDMA). We show that our design criteria are effective for designing phase sequences in SLM. We also show that SLM is more effective than partial transmit sequences (PTS) for reducing the PAPR of MC-CDMA at the same amount of side information.

Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique for achieving high bit-rate transmission in radio environments. Various techniques to estimate channel attenuation have been proposed for OFDM transmission. In these techniques, the added pilot semi-blind (APSB) channel estimation has been proposed, which does not require any additional bandwidth. For an OFDM packet transmission that includes preambles, it is difficult to track the channel variation of the latter of packet due to time-varying channels in fast fading environments. We expect that the channel estimation is improved by applying the APSB channel estimation technique to the last symbols of packets without any additional bandwidth or degradation of bit rate. In this paper, we propose an OFDM packet transmission system with APSB channel estimation technique where this technique is applied to the last symbols of packets. We expect that the proposed system can track the fast time-variant channels without decrease of the data-rate, and the packet error rate (PER) is improved. We show that our proposed system is effective for improving the accuracy of the channel estimate in fast fading channels.