在近幾十年以來，寬頻無線網路蓬勃的發展無疑是為了可以讓使用者能夠無論何時何地都可以享受寬頻網路的服務，但隨之而來的行動裝置的電量消耗變成了一個很重要的問題。
　　在LTE系統的下行鏈路方向(downlink)環境裡，傳統排程機制中的eNodeB會即時性的去根據每一個UE的需求與狀態來做為分配頻寬資源的依據，將頻寬分配給處於醒著(active or light sleep)的UE，但卻沒有將省電機制考量進來，因此在分配頻寬資源時往往會發生超過服務品質需求，造成不必要的電量消耗。
　　因此本論文在LTE環境處於DRX模式的情況下提出一個在下行鏈路方向的排程方法，不僅考慮到電力消耗還將通道狀況一併納入考慮以提高無線電資源的使用效率，並透過動態改變DRX機制的參數設定來提高省電的效益。

In recent decades, broadband wireless access network has been rapidly evolved to allow users enjoying high-speed internet service wherever and whenever, but the ensuing issue of power consumption of mobile devices has become a very important problem.
　　In the traditional scheduling mechanisms in the downlink of LTE system, eNodeB allocates spectrum to the active or light sleep UE according to the information of UE’s need and state, which is the foundation of resource allocation. . However, it doesn’t take power saving mechanism into consideration, which may cause unnecessary power consumption for the reason that UE’s QoS is more than its actual QoS requirement while allocating the resource.
　　In this paper, we propose a downlink scheduling method in LTE system ,taking channel quality, packet delay, and power consumption into consideration , to improve the efficient use of radio resource .Moreover, through the dynamic change of DRX parameter, the efficiency of power saving is enhanced.

[1]S. L. Tsao and Y. L. Chen, “Energy-efficient packet scheduling algorithms for real-time communications in a mobile WiMAX system,”Comput.Commun., vol. 31, no. 10, pp. 2350–2359, Jun. 2008.
[2]http://www.mem.com.tw/article_content.asp?sn=1112020004 (2012/6/19)
[3]Moray Rumney BSc, C. Eng, MIET,"3GPP LTE: Introducing Single-Carrier FDMA,"Agilent Measurement Journal, Issue 4, pp.18-27, January 2008
[4]3GPP TS 36.300 V9.2.0. Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2
[5]3GPP TS 23.401 V9.3.0. General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access
[6]3GPP TS 36.321 V9.0.0, Evolved Universal Terrestrial Radio Access (E-UTRA) Medium Access Control (MAC) protocol specification
[7]De Turck, S. De Vuyst, D. Fiems, S. Wittevrongel, H. Bruneel, "Performance analysis of sleep mode mechanisms in the presence of bidirectional traffic",in Computer Networks Vol.56, no.10, pp.2494–2505 ,5 July 2012
[8]3GPP TSG-RAN WG2 Meeting #57bis, R2-071285,St. Julian’s, Malta, Agenda item:5.2.3, Source: Nokia , Title: DRX parameters in LTE
[9]Jeroen Wigard, Troels Kolding, Lars Dalsgaard, Claudio Coletti, Nokia Siemens Networks, Res. Center Aalborg, Aalborg East, Denmark, "On the User Performance of LTE UE Power Savings Schemes with Discontinuous Reception in LTE", Communications Workshops 2009, pp. 1-5,June 2009
[10]B. Huang, H. Tian, L. Chen, and J. Zhu, “DRX-aware Scheduling Method for Delay-Sensitive Traffic,” IEEE Communications Letters, 14(12), pp. 1113-1115, 2010.
[11]Y. Y. Mihov, K. M. Kassev, and B. P. Tsankov, “Analysis and performance evaluation of the DRX mechanism for power saving in LTE,” in Proc.IEEE IEEEI, pp. 000520–000524, Nov. 2010
[12]3GPP TS 23.203 V9.4.0, Technical Specification Group Services and System Aspects, Policy and charging control architecture
[13]3GPP TS 36.211 V9.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA),Physical Channels and Modulation
[14]3GPP TS 36.213 V9.1.0, Evolved Universal Terrestrial Radio Access (E-UTRA), Physical layer procedures
[15]3GPP TS 36.101, Evolved Universal Terrestrial Radio Access (E-UTRA), User Equipment (UE) radio transmission and reception
[16]3GPP TR 25.892 V6.0.0,Technical Specification Group Radio Access Network, Feasibility Study for Orthogonal Frequency Division Multiplexing (OFDM) for UTRAN enhancement