Space-time trellis code construction for fast fading channels

Abstract—The need for bandwidth- and power-efficient wireless communication systems has raised considerable interest in space-time codes. In this work, we propose a systematic space-time code construction procedure for fast fading channels. The method can be used to design space-time codes for an arbitrary number of transmit antennas and any memoryless modulation. We introduce a new design criterion that ensures full spatial diversity and de-velop the code design method based on this criterion. The flexibil-ity of the proposed approach is demonstrated by designing space-time trellis codes for 2, 3 and 4 transmit antennas with QPSK, 8PSK and 4ASK modulations. I

Rate Efficient Wireless Image Transmission using MIMO-OFDM

In this paper, we propose a rate efficient JPEG 2000 image transmission system over hybrid wireless networks using MIMO-OFDM. The objective is to minimize the expected end-to-end distortion given the rate constraint, which is achieved by jointly adjusting source coding schemes and channel coding rates. In this system, MIMO-OFDM is used to increase the channel capacity and mitigate the inter-symbol interference, variable rate space frequency codes and Reed Solomon codes are adopted to combat the channel errors, and error resilient source coding schemes are applied to restrict the error propagation. In case network congestion may happen, packet erasure codes are used to alleviate the packet dropping. The advantages of the proposed system lie in three aspects: adaptivity, optimality, and low complexity. Based on the characteristics of the image content, the estimated channel conditions, and the distortion constraint, the proposed low-complexity joint source channel coding and rate control algorithm adjusts the coding and transmission strategies adaptively, which can approximate the optimal solution with a tight bound

Diversity analysis of space-time modulation over time-correlated Rayleigh-fading channels

Abstract—Most space–time codes in the literature were proposed based on two ideal channel conditions: either quasi-static or rapid fading. However, these codes may suffer performance degradation due to temporal correlation caused by the movement of the mobile terminal or imperfect interleaving. In this correspondence, we provide a novel analytical framework for the diversity analysis of space–time modulation in time-correlated fading environment. We show that the space–time signals of square size achieving full diversity in quasi-static fading channels also achieve full diversity in time-correlated fading channels, independently of the time correlation matrix. Consequently, various classes of space–time signals designed for quasi-static fading channels can also be used for full-diversity transmission over time-correlated fading channels. Moreover, we show that if the time correlation matrix is of full rank, the design criteria for time-correlated fading channels are the same as those for rapid fading channels. To illustrate the theoretical results, some simulations were also performed under various temporal fading conditions. Index Terms—Diversity, interleaving, multiple antennas, space–time modulation, time-correlated fading

Systematic Design of Space-Time Trellis Codes for Diversity and Coding Advantages

The emerging need for high data rate wireless services has raised considerable interest in space-time coding. In this work, we propose a systematic code construction method that jointly considers diversity advantage and coding advantage for an arbitrary number of transmit antennas and any memoryless constellation. Our approach is to directly assign channel symbols to transmit antennas at different states by exploiting the properties of the state transitions in the trellis. The code construction problem is reduced to a combinatorial optimization problem and a computationally efficient suboptimal solution is proposed. The flexibility of the method is demonstrated by designing space-time trellis codes for QPSK, 8PSK, 16PSK, asymmetric QPSK and 4ASK constellations. Space-time code construction for a large number of transmit antennas (6, 8, and 10) is also considered. The simulations show that our design procedure results in codes that outperform the ones constructed by previously existing methods. The achievable performance gain is governed by the distance structure of the chosen constellation