This paper evaluates the capacity of the reactive decode-and-forward (R-DF) scheme, which considers the reduced relay candidates based on the signal-to-noise ratio (SNR) of the source-relay link for relay selection in underlay cognitive relay networks. The performance of R-DF scheme is compared with that of the proactive DF (P-DF) scheme. It has been proven that R-DF scheme achieves the similar capacity of P-DF scheme as the primary receiver is located further from the secondary source. Since the transmission power of a secondary user is constrained by the location of the primary receiver, the performance of a cognitive relay network varies depending on the considered link for determining the relay candidates, between the source-relay and the relay-destination links. Hence, we also analyze the performance of the backward R-DF (BR-DF) scheme which the relay candidates are determined based on the relay-destination link. It is also verified that the performance of BR-DF scheme is better than that of R-DF scheme when the primary receiver is located close to the secondary source.
Bibliographical noteFunding Information:
This work was supported in part by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2010-0018938) and in part by the MKE (The Ministry of Knowledge Economy), Korea, under the ITRC (Information Technology Research Center) support program supervised by the NIPA (National IT Industry Promotion Agency) (NIPA-2011-(C1090-1111-0005)). Digital Object Identifier 10.1109/TWC.2011.081011.101849
All Science Journal Classification (ASJC) codes
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics