Research Of Optimal Packet Scheduling In A Multiple Access Channel With Energy Harvesting Transmitters

With the wide deployment of battery powered wireless devices, prolonging the lifetime ofwireless networks is becoming ever more critical.So, energy harvesting communication systemshave been widely used in many wireless networking applications as they bring improved lifetimeand ease of deployment.Then, efficient energy management is crucial for wireless communicationsystems, as it increases the throughput and improves the delay.First of all, the optimal packet scheduling problem in a two-user multiple access communicationsystem, where the transmitters are able to harvest energy from the nature without capacity limitation,is investigated. The packets have already arrived and are ready to be transmitted at the transmittersbefore the transmission starts. Through controlling the transmission powers and transmission ratesof both users is to minimize the time by which all packets from both users are delivered to thedestination. Due to this problem is not a convex problem, we slove its dual problem which is aconvex problem. Then, by a waterfilling algorithm characterize the maximum throughput for anygiven deadline constraint T. By this dual problem, the transmission completion time minimizationproblem is simplified into a convex optimization problem. The simulation results show that thesuggested algorithm can solve the overall problem efficiently in this scenario.Then, the minimization of the transmission completion time with a battery limited energyhavesting transmitter, in a two-user multiple access communication system, where the transmittersare able to harvest energy from the nature, is considered. The packets have already arrived and areready to be transmitted at the transmitter before the transmission starts. The energy harvesting timesand harvested energy amounts are known before the transmission starts. Due to the finite batterycapacity, energy may overflow without being utilized for data transmission. So adding a constraintmakes energy not overflow. Similar this minimization of the transmission completion time problemis not a convex problem, we slove its dual problem which is a convex problem using a dual problem.Then, by a directional water-filling algorithm characterize the maximum throughput for any givendeadline constraint T. The optimal transmit power sequence is finded by a directional water-fillingalgorithm. The simulation results show that the suggested algorithm can solve the overall problemwith limited capacity of one transmitter.