Comparative performance of multi-antenna decode and forward relay network

ABSTRACT

Cooperative relaying is an effective technique to combat multi-path fading, improves system capacity and enhances the coverage. In this paper, three different types of operations of infrastructure-based multi-antenna cooperative relay network have been investigated. Closed form expressions of outage probability and average error rate for each type of operation have been derived, when the relay and destination perform maximum ratio combining (MRC) of signals. The effect of antennas installed on relay and its placement has also been studied in this work.

KEYWORDS:

• Outage probability
• average error rate
• MRC
• multi-antenna relay
• adaptive decode and forward mode
• Rayleigh fading channel

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. In this paper, symbol $r_k$ represents the $k^{th}$ receiving antenna of r and $r_o$ represents transmitting antenna of r.

2. In low SNR condition, performance of conventional decode and forward scheme may suffer because relay may erroneously decode the transmitted symbol. So for avoiding error propagation in next stage decoding process at relay can be done adaptively. In adaptive decoding, relay only decode the transmitted symbol if signal strength is above a particular threshold else relay not involved in decoding process.

3. We have assumed that all receivers (r and d) have full CSI but all transmitters (s and r) do not have prior knowledge of CSI.

4. In this paper, we have assumed that the relay will remain silent if received signal strength is below a predefined threshold $\chi$.

5. In type-3 mode of operation, the source will be in inactive mode if relay is in active mode.

6. MGF is the laplace transform of given PDF, i.e. $MGF={\int }_0^{\mathrm{\infty }}{f}_{\mathrm{\Theta }}^{(1)}\left(\theta \right)exp\left(-s\theta \right)d\theta$.