Qing F. Zhou

Outage Performance of Cooperative Communication Systems Using Opportunistic Relaying and Selection Combining Receiver

We analyze the performance of cooperative communication systems with opportunistic decode-and-forward for relaying and selection combining receiver at the destination. We derive an exact closed-form expression for the outage of the system over dissimilar Nakagami fading channels. Also, we study its asymptotic outage performance, based on which the optimum power allocations for the source and the relays are determined. Finally, we verify the theoretical results by simulations.

Two incremental relaying protocols for cooperative networks

The authors investigate a cooperative network with three terminals. By exploiting a simple two-bit feedback message from the destination, two incremental relaying protocols are proposed, namely incremental selection amplify-and-forward (ISAF) and joint incremental selection relaying (JISR) with an aim to balance the load between the source and the relay. The authors derive the asymptotic outage probabilities of the two new protocols and find them to be lower than that of the incremental amplify-and-forward (IAF) protocol, which has been identified as the best protocol so far. Moreover, the spectral efficiencies of ISAF and JISR match that of IAF. Simulation results have verified the asymptotic performance of the protocols and have shown that JISR outperforms ISAF and IAF over all signal-to-noise ratio values.

High-SNR Analysis of Opportunistic Relaying Based on the Maximum Harmonic Mean Selection Criterion

In this letter, we consider a cooperative communication network over Rayleigh fading channels. We assume that the amplify-and-forward (AF) and the selection decode-and-forward (SDF) opportunistic relaying methods are used and that the relay with the largest harmonic mean of the source-relay channel gain and the relay-destination channel gain is selected for forwarding the message to the destination. We derive the high-SNR outage probabilities, which are then compared with the simulation results. We also compare our analytical results with the high-SNR outage probabilities found when the max-min criterion is used to select the opportunistic relay.

Analytical performance of M-ary time-hopping orthogonal PPM UWB systems under multiple access interference

In this paper, we extend the characteristic-function approach to derive an exact symbol error rate expression for the M-ary time-hopping orthogonal pulse position modulation (THPPM) ultra-wideband (UWB) system under the interference from multiple users. Monte Carlo simulations are then used to validate the analytical solutions. The results are found to be valid even when that the chip width is greater than the pulse duration. Moreover, the analytical results are compared to those found by Gaussian approximation and the Gaussian quadrature rule method. We further show that compared to a binary system, M-ary systems can produce better error rate performance.

Performance Bounds of Opportunistic Cooperative Communications With CSI-Assisted Amplify-and-Forward Relaying and MRC Reception

Analytically studying the outage performance of channel-state-information (CSI)-assisted amplify-and-forward (AF) cooperative networks with maximal ratio combining (MRC) receivers at the destination has always been a difficult task. In this paper, we will derive upper and lower performance bounds - including outage probability, ergodic achievable rate, and average symbol error rate - for such a network that selects the “best relay” out of multiple relays to carry out the relay transmission. Our results show that the derived analytical bounds are able to accurately predict the simulated performance. The analytical technique used here can further be applied to investigate multiple-relay systems under dissimilar fading channel conditions.

Performance Analysis of Orthogonal Space-Time Block codes over Nakagami-q (Hoyt) Fading channels

In this paper, we investigate the orthogonal space-time block codes communication systems with various M-ary modulation schemes over independent identically distributed (i.i.d) Nakagami-q (Hoyt) fading channels. We derive exact closed-form expressions of the system performances in terms of symbol error rate (SER). These expressions are composed of Lauricellas multivariate hypergeometric functions, which are easily evaluated numerically.

Performance analysis of serial cooperative communications with decode-and-forward relaying and blind-EGC reception under nakagami fading channels

We analyze a serial cooperative transmission system with DF relaying over Nakagami fading channels. We consider a system in which the simple receivers will not estimate the amplitude of the received signals. Hence, signals are combined with equal gain before decoding. Moreover, the relays use a simple protocol when relaying the messages - they re-transmit the message if they can decode the received message correctly; otherwise, they do not transmit anything and remain idle. We will derive an exact expression for the asymptotic symbol error rate of the system and evaluate the diversity properties.

Closed-form expressions for symbol error probability of orthogonal space-time block codes over Rician-Nakagami channels

The performances of orthogonal space–time block codes (OSTBCs) over Rician–Nakagami channels are investigated. In particular, we derive closed-form symbol error probability (SEP) expressions for OSTBC systems in which M-ary phase-shift-keying modulation and M-ary quadrature-amplitude modulation are used. These SEP results are expressed in terms of Lauricellas multivariate hypergeometric functions, which can be easily evaluated numerically. When the Rician–Nakagami channel degenerates to the Rician–Rayleigh channel, or equivalently the Rayleigh fading channel, the closed-form SEP expressions are rewritten in terms of higher transcendental functions, that is, Gauss hypergeometric function and Appell hypergeometric function.

Selection of spatially-distributed relays for two-way relaying with network coding

To help exchanging information between two sources in a two-way relaying network with multiple relays, we consider selecting one “best” relay or a pair of “best” relays that broadcast network-coded information to other nodes (source or relay). Further, we assume that the multiple relays are random distributed in a one-dimensional or two-dimensional space between the sources and we take the path loss between the nodes into consideration. We also select the relay(s) based on the max-min criterion in both the Single Relay Selection (SRS) scheme and the Paired-Relay Selection (PRS) scheme. In particular, we propose a Distributed VIterbi Selection Algorithm (DVISA) that selects the pair of “best” relays in the PRS scheme and we describe how the nodes exchange information in a frame consisting of 4 time slots. Both our analytical and simulation results show that when the path-loss exponent is large and/or there is a sufficient number of relays to choose from, using two relay nodes can provide a lower outage compared with using only one relay node even under the same total transmit power.