Abstract
The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.
Highlights
Wireless systems have become central to business and daily life
The performance of the cognitive CSMA/CA protocol is analysed by studying the interference the secondary user transmitter causes to the primary user receiver, and how this interference affects the performance of the network in terms of retransmission as a results of packet loss and its impact on the network throughput
Regulatory bodies are becoming aware of the significance of opening up the TV white space which would give an improvement in the spectrum utilization and lead to increased revenue generation
Summary
Wireless systems have become central to business and daily life. There are over five billion mobile cellular users across the world, Parkes et al, [1] and the demand of the wireless technologies and services increases rapidly every year. Interference Mitigation MAC Protocol for Cognitive Radio Networks tion of a wireless microphone using TV white space. Geirhofer et al [11] propose a cognitive resource management protocol that, based on sensing, the infrastructure system allocates transmit power and transmission time to reduce interference. This leads to an interference-aware resource allocation. Auer et al, [13] propose an interference aware medium access for dynamic spectrum sharing; a receiver transmits a busy signal in an adjacent time multiplexed mini slot upon data reception. This paper describes an electromagnetic interference avoidance (EMA) MAC protocol designed to enable dynamic spectrum access (DSA) to TV white space. While the personal/portable devices are allowed to transmit with a maximum EIRP of 100 mW (with PSD of 1.67 mW/100 kHz) on channels non-adjacent to TV broadcast services and 40 mW (with PSD of 0.7 mW/100 kHz) on channels adjacent to an active TV broadcasting channel
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