A Cooperative Energy-saving Algorithm Based On Dynamic Thresholds In Heterogeneous Wireless Networks

In recent years, in order to meet the people ubiquitous wireless access and a variety ofbusiness requirements, mobile communication technology flourished, a variety of newtechnologies and new services are emerging continually. With the continuous expansion ofwireless networks, rapid growth of terminal and network equipment in energy consumptionhas the energy consumption of wireless networks caused widespread concern. In order toprovide people with diversified services and seamless access, various wireless accessnetworks of overlapping coverage are developing in the direction of integration. Futuremobile communication networks will be an all-IP based heterogeneous wireless networks(HWNs). The wireless network traffic is unevenly distributed in time and space, so that theoverlapping area in the case of low load will appear a large number of idle resources,resulting in a serious waste of energy consumption. Therefore, energy-saving has becomeone of the hot issues in HWNs.The status of related researches shows that the study of cooperative energy-saving forHWNs lacks, and has the following problems: energy-saving algorithms using theoreticalderivation such as queuing theory to evaluate the performance of the algorithms only fortime slot, carrier frequency or base station single granularity; energy-saving algorithmscombining time slot,carrier frequency or base station multiple granularities, whichconclude only through simulation statistics, there is no analysis of the performance of thealgorithms theoretically. In response to these problems, the article proposes a newcooperative energy-saving algorithm on account of multiple granularities for HWNs,evaluates and analyzes the performance of the algorithm by queuing theory.In UMTS/WLAN heterogeneous converged network environment, this articleproposes a cooperative energy-saving algorithm based on dynamic thresholds in HWNs.The proposed algorithm sets two load thresholds for energy-saving trigger and wake-upseparately, when the system load is below the trigger threshold, users who connect toWLAN are forced transferred to the UMTS network, WLAN switches to the sleeping state;when the system load is higher than the wake-up threshold, WLAN switches to the workingstate; UMTS network is always active and dynamically switches carrier frequencyaccording to its load. In this paper, queuing theory is used to model the proposed algorithm;the thresholds are dynamically adjusted to ensure quality of service under different userarrival rate by the established multi-dimensional Markov queuing model. Simulation resultsshow that the proposed algorithm compared to the algorithm dynamically switching thecarrier frequency, has better energy-saving effect and higher resource utilization on thepremise of the guarantee system performance. In proposed cooperative energy-saving algorithm based on dynamic thresholds, whenthe system load reached wake-up threshold, the arrival of a new user immediately awakensWLAN, if the new user is beyond the scope of its coverage, which will result in increasingpower consumption in vain. To avoid this problem and further reduce the powerconsumption of the heterogeneous systems, the proposed algorithm has been improved byusing a single base station positioning technology. In improved algorithm, when the systemload reaches the wake-up threshold, WLAN is waked up only the new user located in itscoverage. Simulation results show that the improved algorithm can achieve furtherdecrease power consumption and improve resource utilization.The results of this study have great theoretical significance and application value forenergy-saving optimization design in HWNs.