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In order to achieve dynamic spectrum access in cognitive radio networks, many MAC protocols are proposed to split the shared spectrum into a common control channel and several data channels. The common control channel is used to negotiate data channels and control their access; however, it is confronted with the performance bottleneck. In this paper, an analytical framework is presented to solve this...
We consider a wireless cognitive radio network in which a set of secondary users (SUs) opportunistically utilize the wireless spectrum licensed to the primary users (PUs) to transmit packets to the secondary base station (SBS). It is challenging to maximize the spectrum utilization while limiting the interference imposed to PUs due to SUs. To achieve the optimal tradeoff between the spectrum utilization...
This paper focuses on the spectrum sensing issues in the unslotted cognitive radio networks with wireless fading channels. To overcome the energy-inefficiency problem of the existing continuous/fixed-schedule spectrum sensing schemes in the cognitive radio networks, we propose an efficient spectrum sensing scheme for secondary users (SUs). The design goal of our proposed scheme is to save the sensing...
We propose the queue-aware spectrum sensing schemes for interference-constrained opportunistic transmissions of secondary users (SUs) in cognitive radio networks. Specifically, we employ the energy detection for SUs to sense the spectrum-usage status of the primary users (PUs). Unlike the traditional energy detector using a fixed energy threshold to decide the presence of the PUs' signals, we dynamically...
Cognitive radio technology is widely accepted as an efficient approach to solve the problem that the wireless spectrum has been getting scarcer and scarcer due to the rapid growth in the ubiquitous wireless applications. Several cognitive medium access control (MAC) protocols have been proposed for the secondary users (non-licensed users) to take advantage of the vacant channels whenever they are...
This paper proposes an adaptive code division multiple access (CDMA) based cognitive medium access control (MAC) scheme for uplink cognitive radio networks. The proposed scheme addresses the joint channel sensing and data transmission, power and rate assignments, and long-term fairness. Under our proposed scheme, the secondary users (SUs) can adaptively select either the intrusive spectrum sharing...
Cognitive radio technology is widely accepted as an efficient approach to solve the problem that the wireless spectrum has been getting scarcer and scarcer due to the rapid growth in the ubiquitous wireless applications. Several cognitive medium access control (MAC) protocols have been proposed for the secondary users (non-licensed users) to take advantage of the vacant channels whenever they are...
To improve the utilization of the precious radio spectrum, we propose a channel-hopping based cognitive radio medium access control (MAC) protocol for synchronized wireless networks that can enable the secondary (unlicensed) users to opportunistically utilize the unused licensed-spectrum without interfering with the primary (licensed) users. In our proposed scheme, the secondary users switch across...
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