Haiyang Fu

Superposition coding cooperative relaying communications: Outage performance analysis

User cooperative is a powerful tool to combat fading and to increase robustness for communications over wireless channels. For cooperative relaying communications, the outage probability and the expected rate (throughput) can be greatly improved when the superposition coding relaying (SC-relaying) strategy is employed. Under the assumption of high signal-to-noise ratio (SNR), this work contributes to a comprehensive investigation on the outage probability and the throughput of cooperative relaying communications system with only two-level rate SC. Through strict mathematical process and deduction, the approximated close-form expressions of the outage probabilities and the throughput of system are obtained for the first time. Based on the results, the impact of power and channel allocation fractions on system performance is carried out. With the aim of maximal throughput, a set of optimal solutions of system parameters are obtained by employing difference evolution arithmetic. The comparative numerical analyses show that the approximation results are feasible and correct. Copyright

Two-way denoise-and-forward network coding opportunistic relaying with jointing adaptive modulation relay selection criterions

To improve the performance of the two-way denoise-and-forward network coding opportunistic relaying systems (TW-DNF-OR), two novel best-relay selection criterions are presented, which are the jointing adaptive modulation max-min criterion (AM-MM) and the jointing adaptive modulation maximum harmonic mean criterion (AM-MHM). In the proposed AM-MM and AM-MHM criterions, the effect of the modulation schemes used at both sources is exploited perfectly by integrating the adaptive modulation with the max-min and maximum harmonic mean criterions. On the basis of the proposed AM-MM and AM-MHM criterions, the authors analyse the symbol error probability (SEP) of the TW-DNF-OR systems under independent and non-identically distributed Rayleigh fading channels, and obtain the analytical expressions to the approximate upper bounds of the overall average SEPs. The comparison analyses show that the average SEP of TW-DNF-OR is improved greatly when the proposed jointing adaptive modulation best relay selection criterions are used. Moreover, in certain channel realisations or signal-to-noise ratio regions, the adaptive modulation non-selection TW-DNF-OR systems outperform the conventional best relay selection systems in which the adaptive modulation is not integrated with the best relay selection criterions.

Comparison of average symbol error rate and optimal power allocation for two-way opportunistic relaying with amplify-and-forward protocol

In this paper, we investigate the statistical characteristics of the equivalent end-to-end signal-to-noise ratios SNRs, the average symbol error ratios SERs, and the optimal power allocation OPA for two-way amplify-and-forward opportunistic relaying TWOR-AF systems. First, with strict mathematic manipulation, we obtain the closed-form solutions to the PDF, CDF, and moment generating function of the end-to-end SNRs. Then, based on the obtained statistical results, we present the total average SER of the Non-OPA TWOR-AF systems by using the appropriate approximation, in which only the greater segment of the two terminal SERs is considered. Finally, by aiming at minimizing the total average SER and using the SNRs balancing condition at both transceivers, we study the OPA problem subject to a total transmission power constraint. The comparison analysis shows that, for the Non-OPA TWOR-AF systems, we can only evaluate exactly the greater segment of the two SERs of the received signals at two transceivers by using the derivations. However, for the OPA TWOR-AF systems, with our derivations we can evaluate exactly not only each segment of the two terminal SERs but also the sum SER exact total SER. Moreover, the simulations show the OPA TWOR-AF systems outperform the Non-OPA TWOR-AF systems. Copyright

Tight performance bounds for two-way opportunistic amplify-and-forward wireless relaying networks with TDBC protocols

Based on amplify-and-forward network coding (AFNC) protocol, the outage probability and ergodic capacity of two-way network coding opportunistic relaying (TWOR-AFNC) systems are investigated as well as the corresponding closed-form solutions. For the TWOR-AFNC systems, it is investigated under two scenarios, namely, the TWOR-AFNC systems without direct link (TWOR-AFNC-Nodir) and the TWOR-AFNC systems with direct link (TWOR-AFNC-Dir). First, we investigate TWOR-AFNC-Nodir systems by employing the approximate analysis in high SNR, and obtain closed-form solutions to the cumulative distribution function (CDF) and the probability density function (PDF) of the instantaneous end-to-end signal-to-noise ratio (SNR) with very simple expressions. The derived simple expressions are given by defining an equivalent variable ωeq-k (θ), 2 ≤ θ ≤ 3. When θ = 2, the derived results are the tight lower bounds to CDF and PDF. The sequent simulation demonstrates that the derived tight lower bounds are also very effective over the entire SNR region though which the results are derived in high SNR approximation. Then, with the derived tight closed-form lower bound solutions (θ = 2) in TWOR-AFNC-Nodir systems, we investigate TWOR-AFNC-Dir systems as well as the overall comparison of the outage probability and the ergodic capacity between the two system models. The comparison analysis performed over path loss model basis shows that, in urban environment, due to utilizing the direct link the TWOR-AFNC-Dir outperform considerably the TWOR-AF-Nodir systems. However, when the value of path loss exponent is relatively large, the achievable gain is very small and the direct link can be omitted. In this case, the TWOR-AFNC-Dir model can be displaced by TWOR-AFNC-Nodir model having lower implementation complexity.

Performance Analyses of the N---Rth Dual Best Relays Opportunistic Cooperation with Amplify-and-Forward Protocols

To overcome the loss in the outage probability and symbol error ratio (SER) caused by the Nth single relay opportunistic relaying (OR), in this paper, we present the N–Rth dual best relays OR schemes in which there are two relays selected out of the available relays to forward the received signals to destination over orthogonal channels by using amplify-and-forward protocols. For the proposed N–Rth OR schemes, we obtain firstly the closed-form expressions to the probability density function (PDF) and cumulative distribution function of the instantaneous end-to-end signal-to-noise ratio (SNR) by using the appropriate mathematical manipulations over independent and non-identically distributed Rayleigh fading channels. Then, based on the derived statistical descriptions, the outage probability, average SER, and ergodic capacity of the proposed dual relays OR schemes are investigated as well as the corresponding closed-form analytical solutions. The fair comparison analyses between the Nth schemes and the N–Rth schemes show that the proposed N–Rth schemes can improve greatly the outage probability and average SER of the considered OR schemes in medium and high power transmission regions (or SNR). Especially, the proposed dual relays OR schemes can provide more improvement on SER than outage probability. At the same time, the presented numerical results indicate clearly the improvement on the outage probability and average SER is at the price of the loss in the ergodic capacity, which is due to the constrain of diversity and multiplexing tradeoff in cooperative communications.

N-Rth dual best relays opportunistic cooperation schemes and performance analyses over nakagami-m fading channels

To overcome the performance loss caused by the N th single best relay selection schemes, in this study, the authors present the N-R th dual best relays selection schemes. In the proposed schemes, there are two relays selected out of the available relays to forward the received signals to the destination by using the decode-and-forward protocol. The statistical descriptions of instantaneous end-to-end received signal-to-noise ratios (SNR) are investigated over independent and non-identically distributed Nakagami- m fading channels. By using the appropriate mathematical proof, the authors firstly obtain the closed-form expressions to the probability density function and cumulative distribution function of instantaneous end-to-end SNR. Then, based on the derived results, the outage probability and average symbol error rate (SER) of the proposed N-R th dual best relays selection schemes are investigated. The comparison analyses between the N th schemes and the N-R th schemes show that the proposed N-R th dual best relays selection schemes can improve greatly the performance of opportunistic relaying systems such as outage probability and average SER. Especially, the proposed dual best relays selection scheme can obtain more outstanding improvement on SER.

An Easy Rake Receiver for TD-SCDMA Smart Antenna

The application research on smart antenna (SA) for CDMA system is consists of two parts in general. One part is the research on mathematical methods in SA technology, i.e., how to isolate the array manifold parameter

Research on the power exponent and the outage exponent in superposition coding relaying strategy

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