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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Article
Author(s)
Mohamed Elalem and Lian Zhao
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DOI:10.17265/1548-7709/2013.07 016
Affiliation(s)
ABSTRACT
In cognitive radio networks, a SU (secondary user) can share the same frequency band with the PU (primary user) as long as the interference introduced to the latter is below a predefined threshold. In this paper, the transmission performance in cognitive radio networks is studied assuming imperfect channel estimation, taking (quality of service) constraints into consideration. It is assumed that the cognitive transmitter can perform channel estimation and send the data at two different rates and power levels depending on the activity of the PU. The existence of the PU can be detected by channel sensing. A two-state Markov chain process is used to model the existence of the PUs. The cognitive transmission is also configured as a state transition model depending on whether the rates are higher or lower than the instantaneous rate values. The maximum capacity of the SU under the delay constraint is investigated. The concept of effective capacity of the channel is applied. An optimization problem for rate and power allocation under interference and power constraints is formulated and solved. Numerical results are presented to illustrate the average effective capacity optimization and the impact of other system parameters.
KEYWORDS
Cognitive radio, effective capacity, PAT, MMSE, spectrum sensing
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