Space-time block code (STBC) with complex orthogonal designs achieves full diversity with a simple maximum-likelihood (ML) decoding, however, do not achieve a full transmission rate for more than two antennas. To attain a higher transmission rate, STBC with quasi-orthogonal designs were proposed, whereas there are interference terms caused by relaxing the orthogonality. It has an impact on decoding complexity because a receiver needs to decode two symbols at a time. Moreover, QO-STBC does not achieve full diversity. In this paper, we propose a scheme which makes possible to decode symbols one by one, and two schemes which gain full transmission diversity by upsetting the balance of the transmit power and rotating constellation.

This paper presents a new unequal error protection (UEP) image transmission system that incorporates a Lifting Wavelet Transform (LWT) and Reed Solomon (RS) coded cooperation scheme to increase image transmission diversity, as well as save transmission bandwidth. Having a partner to assist direct communication increases the resilience of low frequency subband data against an error-prone fading channel. Low frequency subbands are partitioned into two sets of data and transmitted using the RS coded cooperation scheme. High frequency subbands data are transmitted directly to a base station. Results show that the new UEP image transmission system using LWT based RS coded cooperation scheme achieves diversity gains of around 10 dB, with channel SNR from 10 to 20 dB, compared with the image transmission system with non-cooperative system under slow Rayleigh fading channel for all levels of LWT decomposition. In addition, the new UEP image transmission system using LWT based RS coded cooperation scheme with one level of wavelet decomposition offers around 37.5% bandwidth gain (β), compared with the system without LWT, which incurs a reduction of 3 dB in reconstructed image quality.

Multi-carrier (MC) signal has a large peak to mean envelope power ratio, so that the MC signal suffers from a high level of inter-modulation distortion due to the nonlinearity of the power amplifier stage. For portable terminals, it is undesirable to use linear amplifiers because high power efficiency is needed. To solve this problem, we propose a time division duplex (TDD)-code division multiple access (CDMA) communication system which uses an asymmetric modulation scheme between the forward and reverse links. The system consists of multicarrier modulation for the forward link and single carrier modulation for the reverse link. A pre-equalization method for the forward link transmission is also presented in this paper. In frequency selective fading, the system achieves a path diversity effect without any channel estimation unit at the mobile station by using the pre-phase equalizer. From the simulation results, it it found that the proposed system achieves better BER performance than the conventional MC-CDMA system and the single carrier RAKE system equipped at the mobile unit since the proposed system has the ability to suppress other user interfering signals.

This paper presents a novel transmission diversity scheme for code division multiple access system. Conventional diversity receivers in mobile stations require space and complicated circuits, however, the proposed diversity schemes present significant diversity effect without any diversity equipment at the mobile station. It is possible to use the transmitter diversity at the base station by using the feature of time division duplex (TDD) which has strongly correlated fading patterns in both forward and reverse link. Computer simulation is performed to evaluate the performance of the proposed systems for single user environment. The performance of the system 1, which select best situated antenna, is analyzed and the BER performance for multiple access is presented.

This paper proposes linear predictive transmission diversity for TDMA/TDD personal communication systems and evaluates the effects of fading correlation and unequal average signal power Rayleigh fading on these system. The average bit error rate (BER) performance is calculated by computer simulation and the BER of zero order prediction is theoretically analyzed. The performance degradation caused by the error from prediction, fading correlation, and unequal average signal power is found to be almost independent of each other.

ISM band has been approved for spread spectrum communication in radio LAN in Japan since December 1992. This frequency band extends from 2.474 GHz to 2.5 GHz with 26 MHz bandwide. In an indoor environment, the maximum observed delay spread is 100-200 ns in a room, it is too short to generate a selective fading, thus flat fading conditions are often observed. Serve as an alleviation, we propose a new system of multi-antenna in base station (BS) and single antenna in mobile station (MS). In this system, MS should have a simple structure for its small size and energy-saving.