تجزیه و تحلیل عملکرد از سیستم تنوع تعاونی ARQ با رله های دو هاپ چندگانه در طول کانال های محو ریلی
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|28261||2013||10 صفحه PDF||سفارش دهید||4878 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Computers & Electrical Engineering, Volume 39, Issue 5, July 2013, Pages 1399–1408
Cooperative communication systems can exploit spatial diversity by opportunistically choosing relays to forward information to the destination. In this paper, we investigate the statistical performance analysis of a general cross-layer automatic repeat request cooperative diversity (ACD) system by focusing on the scenario in which decode-and-forward relaying protocol and multiple two-hop relays are employed over Rayleigh fading channel environments. To obtain the theoretical closed-form formulas for end-to-end performance parameters, we develop a time division multiple access (TDMA)-based absorbing Markov model to help find all possible transition probabilities of each transmission process. Based on this proposed model and statistical analysis, we derive two tight closed-form expressions in terms of end-to-end packet delivery failure probability and end-to-end packet delivery delay distribution. In addition, an optimal power allocation scheme under a tight power constraint for the ACD system is proposed for further enhancing the symbol error rate (SER) performance, which outperforms the equal power allocation scheme obviously. Simulation results by Monte Carlo simulations demonstrate the correctness of our analysis eventually.
Cooperative diversity has shown to play a major role in the next-generation mobile communication networks based on recent work on IEEE802.11s and IEEE802.16j . With low complexity terminals, it is beneficial in enhancing data transmission performance by exploiting the broadcast nature and location dependent fading characteristics of wireless channels. Basically, a transmitting source node can be assisted by its surrounding nodes, if the direct transmission fails. By doing so, multiple copies of independent fading signal paths are provided at the destination, which brings spatial diversity  and . Among the set of cooperative techniques, one most popular strategy for such cooperative diversity systems is the decode-and-forward (DF) relaying protocol  and  where each cooperative node decodes and re-encodes the received signal before forwarding it to the destination. The very early paper on DF cooperative diversity appeared in the single relay over physical layer , ,  and . Most of them have addressed the performance analysis in terms of symbol error rate, outage probability, and capacity. In , Lee et al. considered the true error probability for decode-and-forward cooperative communications with multiple relays over Nakagami-m fading channels. However, they dealt with one-layer symbol error rate analysis without considering upper layers. Recent research work ,  and  has shown that automatic repeat request (ARQ) can improve the multiplexing diversity tradeoff significantly by the retransmission round. In fact, a code division multiple access (CDMA)-based analytical model for ARQ cooperative diversity was proposed in  which validated the desirable adaptive characteristics of cross-layer cooperative communication systems. But the authors focused on the system model where each source node transmitted a packet to its cluster head with its surrounding relays synchronously, if the direct transmission failed. It is not suitable for time division multiple access (TDMA) orthogonal channels, or a single channel for interference. Motivated by all of the above, in this paper, we consider the ACD system in TDMA orthogonal channels with multiple two-hop relays and present statistical performance analysis of ACD system in terms of packet delivery failure probability and packet delivery delay distribution over Rayleigh fading channels in wireless networks. In order to take all possible transition probabilities of each transmission process into consideration, we develop an absorbing Markov model to help find their exact representations in the case of cooperative communications with retransmission round. In addition, we discuss the relationship of the power allocation scheme over different fading channels with the symbol error rate (SER) performance of the cross-layer ACD system. Based on the partial channel state information (CSI) and the analytical results developed, an optimal power allocation scheme is proposed to allocate the transmission power for further improving the performance of system. Afterward, the theoretical analysis is verified by computer Monte Carlo simulations. The numerical results show the correctness of our theoretical expressions for packet delivery failure probability and packet delivery delay distribution. It is also indicated that the performance with optimal power allocation scheme for the cross-layer ACD system is further improved compared with the equal power allocation scheme. The rest of this paper is organized as follows. In Section 2, we describe the system model for the cross-layer ACD system. Then, based on this model, in Section 3, two tight closed-form expressions, i.e. packet delivery failure probability and packet delivery delay distribution, are derived. Section 4 presents an optimal power allocation scheme for enhancing the system SER performance. The numerical results are used in Section 5 and the conclusions are stated in Section 6.
نتیجه گیری انگلیسی
This paper has analyzed the performance of a general cross-layer ACD system with multiple two-hop relays over Rayleigh fading channels. Through the theoretical analysis, the tight closed-form expressions of two important performance metrics, i.e. packet delivery failure probability and packet delivery delay distribution, were derived. Both the theoretical analysis and simulation results demonstrate the effectiveness of our analytical derivations. Additionally, simulation results also show that the optimal power allocation scheme proposed as application outperforms the equal power allocation scheme greatly.