Throughput Optimization in Multichannel Cognitive Radios With Hard-Deadline Constraints

In a cognitive radio scenario, we consider a single secondary user (SU) accessing a multichannel system. The SU senses the channels sequentially to detect if a primary user (PU) is occupying the channels and stops its search to access a channel if it offers a significantly high throughput. The optim...

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Bibliographic Details
Published in:IEEE transactions on vehicular technology 2016-04, Vol.65 (4), p.2355-2368
Main Authors: Ewaisha, Ahmed E., Tepedelenlioglu, Cihan
Format: Article
Language:English
Subjects:
Channels
Cognitive radio
Delay
Delays
Interference
Mathematical model
Multichannel
Optimization
Poisson distribution
Policies
Power control
Random walk theory
Sensors
Throughput
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Summary:In a cognitive radio scenario, we consider a single secondary user (SU) accessing a multichannel system. The SU senses the channels sequentially to detect if a primary user (PU) is occupying the channels and stops its search to access a channel if it offers a significantly high throughput. The optimal stopping rule and power control problem is considered. The problem is formulated as an SU's throughput-maximization problem under power, interference, and packet delay constraints. We first show the effect of the optimal stopping rule on packet delay and then solve this optimization problem for both the overlay system, where the SU transmits only at the spectrum holes, and the underlay system, where tolerable interference (or tolerable collision probability) is allowed. We provide closed-form expressions for the optimal stopping rule and show that the optimal power control strategy for this multichannel problem is a modified waterfilling approach. We extend the work to a multi-SU scenario and show that when the number of SUs is large, the complexity of the solution becomes smaller than that of the single-SU case. We discuss the application of this problem in typical networks where packets simultaneously arrive and have the same departure deadline. We further propose an online adaptation policy to the optimal stopping rule that meets the packets' hard-deadline constraint and, at the same time, gives higher throughput than the offline policy.
ISSN:0018-9545
1939-9359
DOI:10.1109/TVT.2015.2425951