Ho Van Khuong

Performance analysis of a decode-and-forward cooperative relaying scheme for MIMO systems

A decode-and-forward cooperative relaying scheme where an NT-antenna source is assisted by several NT-antenna relays to forward its information to a ND-antenna destination is considered. Its symbol error rate (SER) and average transmit power per transmit antenna (ATPT) are derived and validated by computer simulations. Illustrative results over different network topologies show that the considered cooperative relaying scheme offers a significant performance improvement as compared to direct transmission and cooperative relaying without direct link under the same transmission power and bandwidth efficiency.

A bandwidth-efficient cooperative relaying scheme with limited feedback information

We propose a cooperative relaying scheme using a K-antenna relay to assist information transmission of M single-antenna users to a common N-antenna destination, K, N ges M. All M users simultaneously transmit their information in one time-slot to exploit distributed MIMO multiplexing gain and hence high bandwidth efficiency. The relay will inform the detection status of M user signals received in time-slot 1 so that, in time-slot 2, the relay only re-transmits T successfully detected userspsila signals over its T randomly selected antennas (where TlesM) while the (M-T) other users will re-send their signals. Outage probability of the proposed scheme is derived. Numerical results show that the proposed scheme provides significant performance improvement.

Effect of impulsive noise on decode-and-forward cooperative relaying over fading channel

In this paper, the exact symbol error probability expression for a decode-and-forward cooperative relaying scheme using quadrature amplitude modulation (QAM) in the presence of Rayleigh fading and Bernoulli-Gaussian impulsive noise is derived. Different from [1], we only consider the practical receiver structure at the destination without requiring any knowledge of impulsive noise. Also, the source retransmission when the relay fails to detect the source signal is discussed. Analytical results show that cooperative relaying in impulsive noise environment still achieves space diversity and better performance than direct transmission under same bandwidth efficiency and power consumption for any impulse power and impulse rate. However, the source retransmission-assisted cooperative relaying brings negligible improvement.

A bandwidth-efficient cooperative relaying scheme with space-time block coding and iterative decoding

We propose a coded cooperative relaying scheme in which only newly generated parity bits of users are multiplexed, space-time block coded, and forwarded simultaneously by a multi-antenna relay to a common multi-antenna destination if the relay successfully decodes their information in order to improve bandwidth efficiency. Multiplexing introduces correlation between userspsila data, which offers effectively longer codes and facilitates high-performance iterative multi-user decoding at the destination. Additionally, space time block coding makes bit-metrics calculation simple and increases spatial diversity of the received signal. Simulation results show that the proposed scheme significantly outperforms direct transmission under the same transmit power and bandwidth efficiency.

Bandwidth-efficient cooperative MIMO relaying schemes

Coded cooperative MIMO relaying schemes in which all successfully decoded signals from multiple sources are simultaneously forwarded by a multi-antenna relay to a common multi-antenna destination to increase bandwidth efficiency are proposed in this paper. These schemes facilitate the various retransmission strategies at relay and single-user and multi-user iterative decoding techniques at destination, suitable for trade-offs between performance, latency, and complexity. When channel state information (CSI) is available, pre-coding and power allocation at the relay can be exploited to enhance the information transmission reliability over the relay-destination channel, thus improving the overall system performance. Simulation result shows their superiority to direct transmission under the same transmit power and bandwidth efficiency.

Optimal Symbol Power Distribution for Wireless Network Cocast

This paper considers optimal power distribution among transmitted symbols relayed by cooperating users in wireless network cocast (WNC) to minimize aggregate transmit power using geometric programming based only on long-term fading statistics or network topology while guaranteeing a predetermined quality of service (QoS). Results show that the proposed scheme can significantly save energy consumption.

A multi-stage multi-user decode-and-forward cooperative communications scheme using linear combination

Wireless network cocast (WNC) offers a better tradeoff in spatial diversity and transmission delay than the immediate-neighbor cooperation (INC) and the maximal cooperation (MAX) [1]. However, its transmission delay is almost double that of direct transmission (DTX), resulting in a long waiting time for the destination to detect all user signals. Furthermore, cooperation probability1 is low, eventually reducing the spatial diversity order at the destination. This paper solves the above problems by allowing users to linearly combine their own signals with successfully detected partner signals and to perform a simple multi-user detection. Closed-form error performance formulas are derived and validated by computer simulations. Results show that, for low cross-correlation among user signature waveforms, the proposed scheme offers a better performance than WNC and achieves the same transmission delay as DTX. For high cross-correlation, its performance is negligibly degraded as compared to WNC.

Outage-based Decision Strategies for Coded Cooperative Relaying Schemes

Two cooperation decision strategies based on the instantaneous signal-to-noise ratio (SNR) differences between source-destination, source-relay, and relay-destination channels are considered for coded cooperative relaying systems. Upper bounds on outage probability at the destination for the coded cooperative relaying schemes are first derived and exhaustive search is then used for SNR difference values and partitioning to minimize the outage probability for a given range of the SNR differences. Numerical results confirm the performance enhancement offered by the proposed schemes.

Adaptive coded cooperative relaying schemes

Two cooperation decision strategies based on the instantaneous signal-to-noise ratio (SNR) differences between S-D, S-R and R-D channels are considered for adaptive coded cooperative relaying systems. Upper bounds on outage probability at the destination for the coded cooperative relaying schemes are first derived and exhaustive search is then used for SNR difference values and partitioning to minimize the outage probability for a given range of the SNR differences. Numerical results confirm the performance enhancement offered by the proposed schemes.