Joint optimization of spectrum access and power allocation in uplink OFDMA CR-VANETs
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Cognitive radio (CR) is a state-of-the-art technology to solve the spectrum shortage problem for emerging wireless services, which include the CR-enabled vehicular ad hoc networks (CR-VANETs) for vehicle-to-road side unit (RSU) communications. With the increasing demands for high data rate and more reliable mobile services, orthogonal frequency division multiple access (OFDMA) has been often used in such systems. Energy efficiency is an important issue in OFDMA CR-VANETs due to the concern of green communications to transmit the required data in the shortest time, without affecting primary users. In this paper, we proposed an adaptive solution to minimize the overall energy consumption of CR-VANETs as well as maintaining the service quality of Vehicle-to-RSU uplink communications. This goal has been achieved by the means of dynamically selecting different spectrum access schemes for CR-enabled vehicles with relays. Considering the inter-vehicle distances and location information, we formulated a mixed-integer nonlinear constrained optimization problem. A heuristic algorithm based on the greedy strategy and bisection method is then used to solve the formulated problem and it has been evaluated through extensive simulations for different upload data sizes and available communication durations. The acquired results substantiate the efficiency of the proposed solution in terms of energy consumption.
KeywordsCR-VANETs Spectrum access Energy efficiency Orthogonal frequency division multiple access (OFDMA)
This work is supported by the National Natural Science Foundation of China under Grants Nos. 61309027, 61379110, and 61073104, the Scientific Research Fund of Hunan Provincial Education Department under No. 13B148, the Key Research and Development Project of Hunan Science and Technology Plan under No. 2016SK2028, the China Postdoctoral Science Foundation under No. 2013M542136, the Postdoctoral Foundation of Central South University under No. 126224, and in part by NSERC, CFI and BCKDF.
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