Abstract
Different mechanisms have been proposed to solve opportunistic spectrum access (OSA). In order to address spectrum management efficiently, these mechanisms can be divided into four main functionalities, spectrum sensing, decision-making, sharing, and mobility. These functionalities depend on the interpretation and adaptation of different parameters, for example, sensing and data interpretation for adaptive modulation, power adjustments, and changes regarding the range of frequency operation. For the decision-making function, a novel approach is proposed in which coding information is added to the establishment of the communication process thus assisting the medium access control (MAC). The presence of cognitive radio devices in the network coverage range can be controlled or coordinated by using specific redundancy codes. Hence, Reed Solomon (RS) code is used in this paper as part of the handshaking process to provide error correction. In addition, a redundancy strategy based on Rabin’s information dispersal algorithm (IDA) is presented to provide fault tolerance to the communication between cognitive radio devices. In this case, the information is divided into fragments dynamically, and each fragment is coded by an RS code and reassigned to a subset of recipients using alternate paths. This work shows how to optimize spectrum access based on IDA and RS codes to diversify channel occupation without losing significant information with several frequency hops presented in cognitive radio communications. The validations were executed in a discrete event simulator developed in Python. The proposed system for OSA was found to perform better than other approaches using pilot sequences. Our proposal, therefore, provides fault tolerance, to diversify channel occupation, and helps identify the presence of primary and secondary users when a common control channel (CCC) is implemented by the optimization of the spectrum use.
Highlights
The implementation of a practical and useful cognitive radio (CR) device that attempts to achieve opportunistic spectrum access (OSA) requires several functionalities that using current technology results in various open issues to be solved
Zhu et al [19] mentioned that OSA is one of the core technologies of cognitive radio, which emphasizes the intelligence of the network and adapts spectrum utilization, and in this publication, the authors consider the analysis of each channel to evaluate the best option
The proposed system sends five dispersed fragments through different channels and, in case information is interrupted, the information can be retrieved with only three of them (v) A solution algorithm to distribute the communication according to the spectrum holes availability by using backup channels dynamically assigned with information dispersed with the use of Rabin’s information dispersal algorithm (IDA) algorithms (vi) We proposed a method for the decision-making module (DMM) which provides a proactive approach to the decision making process combined with a reactive approach which improves the response of the system (vii) The proposed system considers contention for the medium access control (MAC) rather than a time slot operation or cooperative approaches, this a more practical point of view since most of the systems operated with contention for medium access
Summary
The implementation of a practical and useful cognitive radio (CR) device that attempts to achieve opportunistic spectrum access (OSA) requires several functionalities that using current technology results in various open issues to be solved. Several authors have proposed different functionalities for CR devices which can be divided into four main functionalities, such as spectrum sensing [6, 7], decision-making [8], sharing, and mobility in order to solve the OSA efficiently [9] These functionalities depend on the interpretation and adaptation of different parameters, for example, sensing and data interpretation for adaptive modulation, power adjustments, and the changes regarding the range of frequency operation. The CR device is able to work with current available technology and avoids the use of a dedicated common control channel (CCC) This can be achieved mainly through changing its operation parameters in four domains: space, frequency, time, and coding.
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