Study On Energy Saving Algorithm Based On IEEE802.16e And Simulation

IEEE802.16e is a standard protocol which was proposed by the IEEE 802 workgroup on the basis of IEEE 802.16d. It supports low-speed mobile terminals within the licensed band of 2~6GHz and provides a solution. for wideband wireless access which can not only provide high rate data services but also make the subscribers have mobility. Because of IEEE802.16e emphasizing mobility, its corresponding mobile terminals can only adopt batteries, however the batteries'capacity is confined by the bulk of the mobile device. Therefore, one of the most important design targets of the IEEE802.16e mobile terminals is to reduce the energy consumption. A deeply study to the MAC layer protocol of the IEEE 802.16e was carried out and the function and the key technologies of each sub-layer of the MAC layer was in detail introduced in this paper. In order to understand the sleep mechanism much better, this paper summarized the sleep mechanisms adopted by several mobile communication systems including UMTS, CDMA 2000, WLAN and the IEEE 802.16e comprehensively, and analyzed the similarities and differences of the sleep mechanisms in each mobile communication system.The services are divided into five different types by the MAC layer protocol in the IEEE 802.16e and three types of power saving class (PSC) which aim at different service requirements were defined. Because the second and the third PSC can be regarded as a especial example of the first one, the first one is mostly studied in this paper. Under the situation of the low arrival rate during the SDU transmission from BS to MS, the energy consumption increase greatly because of overlong sleep period so the average energy consumption and the average waiting time of the mobile terminals increase greatly. However the sleep time in the sleep period increases according to the index mode for the ESM which was defined by the IEEE 802.16e, it leads to the rapid increasing of the corresponding sleep time with the increasing of the sleep period. Therefore, the sleep mechanism defined by the IEEE 802.16e still exists some shortcomings.Aiming at above problems, two kinds of new improved algorithms called superposition-growth algorithm(SGA) and step backoff square-growth algorithm(SBSGA) were put forward based on the existing energy saving mechanism in this paper. Each sleep time of the sleep period in the SGA is gotten according to the sum of the sleep time of the two former adjacent sleep periods, namely, T(i)=[T(i-1)+T(i-2)], while the sleep time of the SBSGA is gotten according to T(i)=int[(i-1)2/2]*Tmin. Meanwhile, in order to adjust the increasing speed further and make the energy saving algorithms have better adaptability, another algorithm called marching-growth algorithm (MGA) was proposed in the paper. The sleep time of the sleep period in the SGA increases according to the frame length marching. The results simulated with Matlab prove that the SGA,SBSGA,MGA greatly reduced the average energy consumption and the average waiting time in different degree compared with the ESM. Their total performances are prior to the ESM obviously. The influences caused by the parameters on the energy saving mechanism are validated in this paper. At last, comparing with several different energy saving algorithms, the MGA has the most excellent performances in the energy saving and the response rate, furthermore, it has a low sensitivity to the parameters and has a good robustness.