LTE-TDD網路中整合多個RN與UE之省電睡眠排程機制

Integrated Sleep Scheduling for Multiple Relays and UEs in LTE-TDD

楊鎮銘(Chen-Ming Yang)

指導教授 ： 楊峻權

國立暨南國際大學/科技學院/資訊工程學系/碩士(2016年)

摘要

LTE-Advanced (LTE-A)是目前4G標準的無線網路接取技術，在LTE-A提供100MHz的頻寬，並且當使用者靜止時下載速度可達1Gbps，在高速移動的情況下也可達100Mbps，但由於LTE-A為了要支援更大的訊號覆蓋範圍以及更快的傳輸速度，考慮到成本以及部屬的方便性問題，所以LTE-A網路中加入中繼節點(Relay Node, RN)的概念，行動用戶 (User Equipment, UE)可以選擇直接透過無線訊號與LTE核心網路(Evolved Packet Core, EPC)的基地台(E-UTRAN Donor NodeB, DeNB)連線並進行無線通訊，或是先與RN連線再藉由RN將訊號傳回基地台。另外，LTE還可以依照分工模式分為FDD與TDD，其中LTE TDD (Time-Division Duplex )是LTE的一種分時多工的實作模式，根據不同的TDD configuration在支援非對稱的服務上具有一定的靈活性。此外，由於越來越多的服務在UE上執行，但是電池的技術卻沒有重大的突破，因此，省電的方式一直是眾多無線網路研究中的一大重點。本文探討如何在LTE TDD的網路中，設計以流量為基礎並整合多個RN的省電機制，分析DeNB-RN之間的backhaul link與RN-UE 之間的access link在排程上相互影響的關係，根據backhaul line與access link排程的先後順序分為Top-Down與Bottom-Up的方式來探討排程，並透過虛擬時間軸的概念和對應方法討論省電效能與效率。

關鍵字

時分多工 ； 中繼 ； 省電排程

並列摘要

Long Term Evolution (LTE) is one of radio access technology standard, and it is also the most promising 4G mobile data transmission technology at present. In order to extend the coverage area and provide higher data transmission rates, the key feature of LTE-Advanced (LTE-A), Relay Node (RN), provides the functionality to approach the requirement. As others wireless device, RNs have to face the limited power problem, and one of the solution is power saving scheduling. The standard of power saving scheduling in LTE is Discontinuous Reception (DRX) that the brief of algorithm is switch into sleep mode if there’s no packet arrival after inactivity timer timeout. The cons of DRX is that device has to be awake even only few packets arrival. Therefore, we proposed the Load-Based power saving (LBPS) scheduling to improve the power saving efficiency.
The main purpose of LBPS is to predict the sleep cycle based on current load. In order to predict precisely, previous work has proposed three basic scheme: aggr, split, and merge to calculate the period of sleeping in LTE FDD mode. However, this research, we will integrated the multiple RNs and UEs in Time-Division Duplex (TDD) mode and considering the different link quality between backhaul link (eNB to RNs) and access link (RNs to UEs). The difference in TDD mode is the available subframe is not-continuous. Against the problem of TDD mode, we will transform the real timeline resource to virtual timeline and design a implement mechanism on virtual timeline. After the prediction of LBPS, we design a novel two-hop mapping for translating the virtual result to real result.
Moreover, we propose Top-Down and Bottom-Up of LBPS integration in TDD by the order of scheduling. Top-Down will do the backhaul scheduling first, then do the access scheduling based on backhaul result and vice versa. Top-Down will limit the sleep cycle because of aggregating flow of served UEs. In the other way, Bottom-Up trying to maximize the poser saving efficiency of each UE, but the schedulability of backhaul link will be a problem. We solved all the detail of above question and figure out the result of our proposed scheme can effectively improve the power saving efficiency than two-hop DRX in TDD.

並列關鍵字

TD-LTE ； RN ； Power saving ； LBPS

參考文獻

[1] S. Sesia, I. Toufik and M.P.J. Baker, LTE – The UMTS Long Term Evolution: From Theory to Practice, Wiley, April 2009.

[2] 3GPP TS 36.300, “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN),” Rel. 10, v10.3.0, March 2011.

[3] C.C. Yang, Y.T. Mai, J.Y. Chen, Y.S. Shen, and Y.C. Kuo, “LBPS: Load-Based Power Saving in the IEEE 802.16e Network,” Computers & Electrical Engineering, vol. 38, no. 4, July 2012, pp. 891–905.

[4] C.C. Yang, J.Y. Chen, Y.T. Mai and C.H. Liang, “Design of a Load-based DRX Scheme for Non-Real-Time Traffic in LTE,” accepted by the IAENG International Conference on Communication Systems and Applications (International MultiConference of Engineers and Computer Scientists, IMECS) March, 2014, pp. 12-14.

[5] C-C Yang, J-Y Chen, Y-T Mai, and H-H Liu, “Integrated Power Saving for Relay Node and User Equipment in LTE-A,” accepted by international journal of communication Int. J. Commun. Syst. 2016; 29:1342–1364