Outage Capacity of Incremental Relaying at Low Signal-to-Noise Ratios

Abstract

We present the \epsilon-outage capacity of incremental relaying at low signal-to-noise ratios (SNR) in a wireless cooperative network with slow Rayleigh fading channels. The relay performs decode-and-forward and repetition coding is employed in the network, which is optimal in the low SNR regime. We derive an expression on the optimal relay location that maximizes the \epsilon-outage capacity. It is shown that this location is independent of the outage probability and SNR but only depends on the channel conditions represented by a path-loss factor. We compare our results to the \epsilon-outage capacity of the cut-set bound and demonstrate that the ratio between the \epsilon-outage capacity of incremental relaying and the cut-set bound lies within 1/\sqrt{2} and 1. Furthermore, we derive lower bounds on the \epsilon-outage capacity for the case of K relays

Comparing the Outage Capacity of Transmit Diversity and Incremental Relaying

“…However, the applied method allows the treatment of this variable-rate protocol from an information-theoretic perspective similar to [8]. Results on the behavior of incremental relaying in the low SNR regime can be found in [15].…”

Goodput maximization in cooperative networks with ARQ

“…We have the following key assumptions: 1) channel codes support communication at the instantaneous channel capacity levels, and outages, which occur if transmission rate exceeds the instantaneous channel capacity, lead to packet errors and are perfectly detected at the receivers; 2) depending on whether packets are successfully received or not, ACK or NACK control frames are sent and overheard; 3) ACK/NACK is received reliably with no errors; 4) each codeword contains a certain number of data packets and the transmission of data packets begins when source broadcasts to both relay and destination; 5) the relay mechanism is assumed to be incremental relaying in which the relay node doesn't need to engage in transmission whenever the S-D link is successful [5], [6].…”

“…The variances of the other links are assumed to be proportional to σ 2 ∝ d −α where α is the path loss coefficient [5]. As for the S-R-D cooperative link, by using a generalized distance…”

Incremental Relaying with Imperfect Feedback in Wireless Cooperative Networks

“…We derive the ǫ-outage capacity of incremental relaying by applying the method described in [2]. First, a baseline setting is examined, which means that we derive the ǫ-outage capacity of the corresponding network but without feedback from the destination.…”

“…This was done for decode-and-forward in [2]. The authors derived the ǫ-outage capacity for the general case of K relays when there is perfect feedback from the destination.…”