COGNITIVE RADIO PROTOCOLS USING HYBRID ARQ

Abstract

Recent developments and research have shown significant underutilization of licensed spectrum. Cognitive radios offer the promise of being a technology innovation that will enable the future wireless world. They are fully programmable wireless devices that can sense their environment and dynamically adapt their transmission waveform, channel access method, spectrum use, and networking protocols as needed br good network and application performance. Hybrid ARQ is the combination of Forward error correction scheme and ARQ Scheme which rely on both error detection and error correction combined with retransmission requests. Hybrid ARQ technique is widely used in contemporary communication systems such as the 3GPP LTE standards, IEEE 802.16 standard and mobile Wi MAX systems. We explore the use of hybrid ARQ in cognitive radio networks when primary user uses hybrid ARQ and cognitive user uses various protocols to increase its throughput without causing minimum or no interference to the primary user. Power control algorithms have been implemented in order to reduce the throughput loss of - the primary user. Further by using rate control at the primary user we can improve the performance of the primary user in the presence of secondary user.