Resource allocation and outage performance in OFDMA based cooperative cognitive radio network for downlink in underlay mode

Abstract

Efficient resource allocation is an important process in any network to improve the capacity of a system. In cognitive radio network the resources are shared among licensed & unlicensed users. User is said to be in outage if it does not get required number of resources hence performance of the system gets affected. In this paper the outage probability in orthogonal frequency division multiple access (OFDMA) based cooperative cognitive radio network (CCRN) system is computed. Due to random user position different users require different number of resources. To determine this it is necessary to know the signal to interference ratio (SIR) experienced by the user. First we determine characteristic of interference to signal power ratio by using method of moments. Once the interference to signal power ratio is characterized, user is allocated a class number. Class number gives the number of subcarriers required by a user. For analysis purpose we use downlink in underlay mode with log normal shadowing and path loss exponent. This analysis helps in allocation of resources to the user depending on SIR experienced and outage behavior irrespective of user’s position.