Multiple-channel Based Active DRX And Its Performance Evaluation

With the development of communication technology, the functions of the mobileterminal are becoming ever more enhanced, however, the requirement for energy to powerthe system becomes greater than before. How to reduce energy consumption andimplement green communication has become the focus of the research in the related fields.Therefore, the LTE (Long Time Evolution project) introduced DRX (DiscontinuousReception) strategy. In this paper, based on the existing Active DRX the performance isevaluated, the strategy is improved and the system is optimized.Firstly, considering the multiple logical channel communication in practical mobileterminals, the conventional Active DRX of LTE is modeled as a queueing system withmultiple synchronous vacation. The system state transition probability matrix isconstructed. By using the Markov chain, the system model is analyzed, and thesteady-state distribution is given. The performance measures, such as the energy savingratio, the system blocking ratio and the response delay of data frames, are derived.Secondly, according to the analysis results for the conventional Active DRXenergy-saving strategy, by considering the trade-off between the saving ratio and theresponse delay of data frames, a sleep-delay mechanism is introduced, then an improvedActive DRX energy-saving strategy is carried out. By building a multiple synchronousvacation queueing system with vocation-delay and set-up, and using the three-dimensionalMarkov chain method, the steady state analysis of system model is given. For theimproved Active DRX energy-saving strategy, the performance measures, such as theenergy saving ratio, the system blocking ratio and the response delay of data frames arepresented.Then, for the conventional Active DRX and the improved Active DRX, thenumerical experiments and simulation experiments are performed respectively. Themeasure trends versus the sleep interval, the number of logical channels and the length ofsleep-delay timer are investigated mathematically. The effectiveness of the improvedActive DRX is verified. At last, based on the trade-off relationship between different measures revealed bythe system experiments, profit functions are established. For the conventional and theimproved Active DRX, the sleep interval, the length of sleep-delay timer, the number oflogical channels and the transmission rate of logical channel are optimized.