A Joint Hybrid-ARQ and Opportunistic InterferenceAlignment based Sum Rate Maximization forCognitive Radio Networks

Abstract

An efficient amalgamation of Opportunistic Inter-ference Alignment (OIA) with Hybrid- Automatic Repeat Request(ARQ) for sum rate maximization of secondary transmission incognitive environment is proposed. Literature survey exhibits ca-pacity improvement by virtue of availability of additional degreeof freedom in spatial domain due to Interference Alignment (IA).Also, the exploitation of opportunities provided during the ARQtransmission results in capacity enhancement of unlicensed user.In the proposed scheme, the secondary user opportunisticallytakes the advantage of spatial degree of freedom available during the primary re transmission. During re transmission, the primaryuser reduces the power allocation in multiple transmitting an-tennis to achieve the same BER performance, thus reducingthe interference caused at the secondary user. This results inimproved sum rate at the secondary user. Simulation resultsshows the significant achievement in the data rates with theemployment of joint ARQ retransmission and OIA technique