Diversity And Multiplexing Tradeoff Research Articles

System Design, DMT Analysis, and Penalty for Non-Coherent Relaying

In a two-hop system with multiple amplify-and-forward (AF) relays, the instantaneous channel state information (CSI) is usually required at the relays to achieve a coherent combining at the destination. In this paper, we investigate the design of non-coherent relaying systems, where no CSI is available at the relays. It will be shown that non-coherent relaying can achieve the optimal diversity and multiplexing tradeoff (DMT) of coherent relaying systems with no penalty in the coding length, but incurs a loss of combining gain. To illustrate the practicality of non-coherent relaying, we propose a simple spreading-based non-coherent relaying scheme which achieves the optimal diversity gain. However, the spreading scheme demonstrates a unique non-coherent penalty, namely, the inclusion of one non-coherent relay may introduce negative contribution to the receive SNR. To handle this penalty, a distributed relay selection scheme, which can achieve a better outage performance with less energy, is proposed.

On Diversity and Multiplexing Tradeoff of Two-Layer D-BLAST with Group Zero-Forcing Detection

Group zero-forcing (GZF) detection is an efficient and powerful detection tool that has flexible detection complexity and performance gain between the optimum detection and the ZF detection. In this paper, we give diversity and multiplexing tradeoff (DMT) analysis for a 2-layer D-BLAST transmission under GZF detection over Rayleigh MIMO channels. With M transmit antennas and N receive antennas, the DMT of such a system is shown as d_{out}(r)=(N-1)(M-\frac{r(M+1)}{2})^+ for \frac{2}{M+1}≤ r≤ \frac{2M}{M+1} and d_{out}(r)=(MN-M+1)-\frac{rN(M+1)}{2} for 0≤ r< \frac{2}{M+1}, where d_{out} denotes the diversity gain and r denotes the multiplexing gain.

Array Gain in the DMT Framework for MIMO Channels

Following the seminal work by Zheng and Tse on the diversity and multiplexing tradeoff (DMT) of multiple-input multiple-output (MIMO) channels, in this paper, we introduce the array gain to investigate the fundamental relation between transmission rate and reliability in MIMO systems. The array gain gives information on the power offset that results from exploiting channel state information at the transmitter or as a consequence of the channel model. Hence, the diversity, multiplexing, and array gain (DMA) analysis is able to cope with the limitations of the original DMT and provide an operational meaning in the sense that the DMA gains of a particular system can be directly translated into a parameterized characterization of its associated outage probability performance. In this paper, we derive the best DMA gains achievable by any scheme employing isotropic signaling in uncorrelated Rayleigh, semicorrelated Rayleigh, and uncorrelated Rician block-fading MIMO channels. We use these results to analyze the effect of important channel parameters on the outage performance at different points of the DMT curve.

Power Control and Channel Training for MIMO Channels: A DMT Perspective

The achievable diversity and multiplexing tradeoff (DMT) in MIMO fading channels with channel training is analyzed in this paper. We first consider a typical training scenario, where the transmitter transmits training symbols followed by data symbols, and the receiver performs channel estimation using the training symbols and then uses the imperfect channel estimates to decode the data symbols. From the DMT perspective, our results show that as long as the training power is equal to the data power, the obtained DMT result based on imperfect channel state information at receiver (CSIR) is the same as the original DMT result with perfect CSIR given in Zheng and Tse's seminal work . We extend the analysis to two-way training scenarios, with single and multiple training rounds. Our results show that two-way training together with power control can substantially improve the achievable diversity gain. Specifically, the achievable DMT with multiple training rounds can be described as a single straight line; while in the case of single training round, the achievable DMT is much lower and can be described as a single straight line or a collection of line segments, depending on the underlying training strategy and channel qualities.

Generalized Sequential Slotted Amplify and Forward Strategy in Cooperative Communications

This paper proposes a generalized sequential slotted amplify and forward (GSSAF) strategy for single-antenna wireless cooperative networks. The diversity and multiplexing tradeoff (DMT) is analyzed. Applications to cooperative multiple relay channels, cooperative broadcast channels (CBC) and cooperative multiple access channels are considered and the DMT upper bound is proven to be achievable for each case. Other than proposing the best known near-optimal strategy for CBC, another important contribution is to show that GSSAF can be used as a unified strategy to achieve DMT optimality in wireless cooperative networks with unit multiplexing gains.

Performance Analysis of Opportunistic and All-Participate Relaying with Imperfect Channel Estimation

For amplify-and-forward (AF) relaying with imperfect channel estimation, we present the average symbol error rate (SER) and the diversity and multiplexing tradeoff (DMT) analysis for both opportunistic relaying (OPR) and all-participate relaying (APR) schemes. SER comparisons show that when the channel estimation quality order is no larger than 1, OPR will perform worse than APR in high SNR region. Moreover, small channel estimation quality orders will also lead to significant DMT loss.

On the diversity gain in cooperative relaying channels with imperfect CSIT

In this paper, we investigate the impact of imperfect channel state information at the transmitters (CSIT) on the achievable diversity gain in a cooperative relaying channel with multiple destination antennas, where the CSIT comes from channel estimation at the transmitters. Both decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols are considered. We show that transmit power control based on the imperfect CSIT significantly improves the achievable diversity gain. The diversity and multiplexing tradeoff (DMT) as a function of the CSIT quality of the source-relay link, source-destination link and relay-destination link is derived for each of the considered relaying schemes. An upper bound on the DMT of the relaying channel is also provided.

Diversity-and-multiplexing tradeoff and throughput of superposition coding relaying strategy

While the Network Coding cooperative relaying (NC-relaying) has the merit of high spectral efficiency, Superposition Coding relaying (SC-relaying) has the merit of high throughput. In this paper, a novel concept, coded cooperative relaying, is presented, which is a unified scheme of the NC-relaying and SC-relaying. For the SC-relaying strategy which can be considered one-way coded relaying scheme with multi-access channel, the close-form solution of the outage probabilities of the basic signal and additional signal are obtained firstly. Secondly, the Diversity-and-Multiplexing Tradeoff (DMT) characteristics of basic signal and additional signal are investigated entirely as well as the optimal close-form solutions. The compared numerical analysis shows the evaluation error of throughput based on the close-form solution is about 0.15 nats, which is within the acceptable error range. Due to the mutual effect between the both source signals, the available maximal values of the two multiplexing gains are less than 1.

Analysis on the Diversity and Multiplexing Tradeoff of Antenna Selected MIMO System

Antenna selection is a practical way to decrease system complexity and the hardware cost of radio frequency (RF) chains in multiple input multiple output (MIMO) system. In this study, we give a simple characterization of the optimal diversity and multiplexing tradeoff (DMT) curve of the MIMO system with antenna subset selection at both the transmitter and the receiver for Rayleigh fading channel.