Exact Closed-Form Expressions for the Outage Probability and Ergodic Capacity of Decode-and-Forward Opportunistic Relaying

Abstract

Exact statistics of the local signal-to-noise ratios (SNRs) of the best relay in decode-and-forward (DF) opportunistic relaying (ORe) are derived. It is observed that although the different links are assumed to suffer independent fadings, the best-relay local SNRs are dependent. Both joint and marginal statistics are determined for the general case of nonidentical SNR distributions, and a source-relay-symmetric (S-R-sym.), relaydestination-symmetric (R-D-sym.) case. Both general fading and Rayleigh fading cases are considered. Using the statistics derived, exact, closed-form expressions for the outage probability and ergodic capacity of DF ORe are calculated in the S-R-sym., R-D-sym., Rayleigh fading case. The exact results for the outage probability show almost linearly increasing diversity order with the number of relays. The exact results for the ergodic capacity show a multiplexing gain almost equaling one half and a power gain increasing with the number of relays that exhibits diminishing returns.

Exact performance analysis of decode-and-forward opportunistic relaying

“…Therefore, It becomes necessary to find the exact statistics of each hop in order to evalu ate the diversity gain (by investigating the combined output SNR) at the final destination. A very interesting recent work appeared where exact closed-form expressions for outage probability and ergodic ca pacity of DF opportunistic relaying are derived [13]. However, the statistics are expressed as integral forms.…”

Throughput analysis of MIMO cooperative decode-and-forward HARQ protocols

“…i,2 , which can be obtained from [9]. Also, R(∞) [5] denotes the achievable rate with the direct link of the protocol proposed in [4], which is given by R(∞) [5] …”

Optimal relay selection for decode-and-forward opportunistic relaying

“…Nevertheless, we found that many papers in the literature, e.g. [4] [6], apply the suboptimal relay selection policy even when they consider link combination at the destination node. For this reason, we This paper was made possible by YSREP grant # 2-011-2-002 from the Qatar National Research Fund (a member of Qatar Foundation).…”

“…This scheme has gained a lot of interest and it was extensively studied in the literature, (see e.g. [3], [4] and references therein). The ORe protocol has been applied for the two common relaying schemes of Amplify-and-Forward (AF) and Decode-and-Forward (DF) [5].…”

“…In [4] and [6], exact closed-form expressions for the outage probability of ORe and selective ORe respectively were given for the common sub-optimal relay selection policy. In [7], [8], the suboptimal relay selection policy was replaced by an optimal (from outage reduction perspective) two-stage selection scheme called selection cooperation (SC) 1 .…”