Abstract
In this article, the performance of cognitive transmission under quality of service (QoS) constraints and interference limitations is studied. Cognitive secondary users are assumed to initially perform sensing over multiple frequency bands (or equivalently channels) to detect the activities of primary users. Subsequently, they perform transmission in a single channel at variable power and rates depending on the channel sensing decisions and the fading environment. A state transition model is constructed to model this cognitive operation. Statistical limitations on the buffer lengths are imposed to take into account the QoS constraints of the cognitive secondary users. Under such QoS constraints and limitations on the interference caused to the primary users, the maximum throughput is identified by finding the effective capacity of the cognitive radio channel. Optimal power allocation strategies are obtained and the optimal channel selection criterion is identified. The intricate interplay between effective capacity, interference and QoS constraints, channel sensing parameters and reliability, fading, and the number of available frequency bands is investigated through numerical results.
Highlights
Recent years have witnessed much interest in cognitive radio systems due to their promise as a technology that enables systems to utilize the available spectrum much more effectively
Effective capacity we identify the maximum throughput that the cognitive radio channel with the aforementioned state-transition model can sustain under interference power constraints and statistical quality of service (QoS) limitations imposed in the form of buffer or delay violation probabilities.b Wu and Negi [11] defined the effective capacity as the maximum constant arrival rate that can be supported by a given channel service process while satisfying a statistical QoS requirement specified by the QoS exponent θ
In this article, we have studied the performance of cognitive transmission under QoS constraints and interference limitations
Summary
Recent years have witnessed much interest in cognitive radio systems due to their promise as a technology that enables systems to utilize the available spectrum much more effectively. Since the transmitter, assuming the channel as idle, sets the power level to P2(i) and expects that no interference from the primary transmissions will be experienced at the secondary receiver (as seen by the absence of σs2p in the denominator of SNR4).
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