在LTE網路下以流量為基礎之省電機制

Load-Based Power Saving in LTE Network

梁景翔(Ching-Hsiang Liang)

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(2014年)

摘要

長期演進技術 (Long Term Evolution, LTE)是由第三代行動通訊組織(Third Generation Partnership Project, 3GPP)所制訂之無線通訊傳輸標準之一，也是目前最有機會成為4G行動數據傳輸技術的標準，LTE採用多種無線技術來提供更高傳輸速率和更低傳輸延遲，然而卻也讓使用者設備的電路複雜度增加，導致電池耗電量上升，因此，使用者設備的能源節省也成為重要的議題，LTE已有採用非連續接收(Discontinuous Reception, DRX)機制來讓使用者設備達到省電的目的，但在原有的標準中並沒有考慮以使用者設備的流量負載的變化量來做調整，可能導致DRX參數配置不合宜，例如：使用者設備在流量負載很高時，若一開始只配置Long DRX cycle，將造成封包延遲上升、能源節省效能或系統效能下降等影響，因此在我們先前的研究中已經有提出在802.16e的環境之下，根據流量負載的變化去制定省電機制(Load Based Power Saving, LBPS)，所以，我們將LBPS概念應用於LTE環境之中，我們會提出LTE-LBPS-Aggr與LTE-LBPS-Merge兩個機制，由於先前的機制並沒有考慮UE的channel quality，因此我們會考慮此因素，在LTE環境下，UE回報的通道品質指標(Channel Quality Indicator, CQI)值又有wideband以及full-sub-band，我們會對這兩種方式各提出一個system capacity的估算，並期望使用者設備能在我們提出的機制下達到有效的能源節省，論文中透過模擬分析的結果，可以看出提出的機制在power saving將有不錯之成效。

關鍵字

LTE ； DRX ； LBPS ； 省電機制 ； CQI

並列摘要

LTE is one of the wireless transmission standards developed by the 3GPP organization, and it is the most likely to become the standard for 4G mobile data transmission technology at present. LTE uses a variety of wireless technologies to provide higher transmission rates and lower transmission delay. But it also increases user equipment circuit complexity and causes the battery consumption to rise. So, energy saving for user equipments has become an important issue. Although LTE has been using DRX mechanism to let user equipments achieve the purpose of energy saving. But DRX mechanism does not consider adjustment DRX parameters by the traffic load of user equipment, so it may lead DRX parameters unsuitable. For example, when user equipment has high traffic loads, and if it only configures Long DRX cycle. That will cause packet delay to rise、energy saving or system utilization decreased and so on. In previous studies have been proposed load base power saving mechanism in the 802.16e environment. So, this paper uses LBPS concept to propose two mechanisms which are LTE-LBPS-Aggr with LTE-LBPS-Merge in LTE environment. But the previous mechanism does not consider the channel quality of user equipment, so this paper considers this factor. In LTE, user equipment uses CQI feedback to notice channel quality for eNB. This paper considers CQI feedback with wideband and full-sub-band and proposes the system capacity estimation for each. And expect the user equipment can achieve more energy saving. Finally through simulation results, we can see that the mechanism of this paper proposed which has good performance in the power saving and average delay.

並列關鍵字

LTE ； DRX ； LBPS ； Power Saving ； CQI

參考文獻

[1] 3GPP, “Radio Access Network; E-UTRA and E-UTRAN Overall Description,” Tech. spec. 3GPP TS 36.300, v. 8.0.0 (2007–03), March 2007.

[2] Roke Manor Research Ltd, “LTE MAC Scheduler & Radio Resource Scheduling,” 2011.

[3] C. Bontu and E. Illidge, “DRX Mechanism for Power Saving in LTE,” IEEE Communications Magazine, vol. 47, no. 6, pp. 48–55, June 2009.

[4] 3GPP, “E-UTRA; Medium Access Control (MAC) Protocol Specification,” Tech. spec. 3GPP TS 36.321, v. 11.2.0 (2013–04), April 2013.

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