LTE系统中的功率节省机制——非连续接收

LTE系统自Release 8就引入了非连续接收（DRX）机制,为终端节省电量.但随着Release版本的不断演进,新技术的不断发展,3GPP RAN2工作组对DRX工作机制和标准也不断进行着研究和完善.本文分别介绍了终端处于RRC_ Idle和RRC Connected状态下DRX工作的基本原理和DRX标准化研究现状,并对DRX功能上可以增强的方面进行了说明,最后对非连续接收技术做出了展望.     

LTE业务的不连续接收节能省电机制

为了降低移动终端的功率消耗,在移动通信系统中引入了不连续接收(Discontinuous Reception,DRX)省电机制。本文分析了在TD-LTE系统中使用DRX机制延长移动终端电池的使用。通过搭建DRX模型,基于分析模型,研究了DRX的省电因素。最后,通过对各种因素的优先性选择实现终端的节能,同时保证用户的优良体验。     

DRX对TD-LTE网络端到端时延的影响

针对LTE系统的DRX(非连续接收)机制进行介绍,系统分析DRX机制引入后对TD-LTE网络端到端时延性能的影响,并基于DRX机制打开和关闭前提对TD-LTE网络Ping包端到端时延进行对比测试分析。测试结果表明,DRX机制引入后,不合理的参数设置以及不同的UE(用户终端)处理能力将对网络时延性能产生影响。     

下一代移动网络中非连续接收机制对移动互联网业务性能影响分析

移动互联网业务的发展引发了大量需要终端与网络间进行频繁交互的业务,产生了终端能量和无线信令资源消耗过度的问题。结合3GPP标准定义的下一代移动网络非连续接收(discontinuous reception,DRX)机制,从终端能耗、数据包延时、空口资源开销等角度出发,分析了DRX机制对典型移动互联网业务的网络性能影响,并对DRX机制的参数配置提出了优化建议。     

TD-LTE系统下的DRX过程的改进与实现

随着移动终端业务的丰富以及智能手机的普及,移动终端电池的续航能力在成为业界关注热点的同时也遇到了严峻的挑战.在LTE系统无线高层协议中,为进一步支持多种业务和大量数据的传输,DRX(非连续接收)机制作为降低终端功耗的重要方法被引入.本文不仅详细描述了DRX在空闲状态和连接状态下的不同原理和机制,而且给出了相应的实现流程与算法,并在此基础上优化了连接态下的DRX算法,从而避免了因无效配置造成的信令开销增大等问题.最后根据不同业务的特性,给出了DRX机制在不同移动业务中的实现,从而更好地改善了终端能耗和信令开销等性能.     

Method of Discontinuous Reception in LTE

针对3GPP的长期演进系统(LTE)的不间断接收(DRX)机制,提出了一种新的DRX的睡眠周期配置方法.该方法根据突发数据业务模型,动态地调整睡眠周期长度.通过仿真分析,该方法可以改善时延特性,并且能有效地降低移动终端的平均能耗.     

一种基于LTE系统的不连续接收方法

针对3GPP的长期演进系统(LTE)的不间断接收(DRX)机制,提出了一种新的DRX的睡眠周期配置方法。该方法根据突发数据业务模型,动态地调整睡眠周期长度。通过仿真分析,该方法可以改善时延特性,并且能有效地降低移动终端的平均能耗。     

不连续接收与电压岛结合的省电方法

LTE系统支持高速的数据传输。高的数据传输速率需要更复杂的基带调制解调器芯片,这就加快了终端电池的能量的消耗。因此,LTE引入了不连续接收机制(DRX)来延长终端的电池试用时间。结合DRX,本文提出了一个动态的电源管理方案—分层多级电压岛(HMVIP),并建立省电类。结果表明,在单一的LTE终端芯片上,DRX结合HMVIP可以达到更好的省电性能。     

基于自适应控制休眠周期的LTE DRX机制研究

针对LTE系统的动态不连续接收机制,系统分析了动态控制LTE DRX周期算法的引入背景,提出了一种基于自适应控制休眠周期的LTEDRX机制,并通过仿真平台对其性能进行了仿真验证。仿真结果表明该算法在能耗和时延2方面均具有良好的性能,可以实现两者之间的有效折衷与权衡。     

LTE系统不连续接收周期配置改进算法研究

考虑到在LTE标准下DRX睡眠间隔是固定的，缺乏灵活性，提出了基于爱尔兰分组数据模型的DRX睡眠间隔指数平滑增长算法。该算法简化了系统结构，加强了相邻睡眠间隔的相关性，配置灵活，能在保证省电性能基础上，有效地降低平均时延、保证用户体验。     

An application aware discontinuous reception mechanism in LTE-advanced with carrier aggregation consideration

3GPP Release 8 specifications define a mechanism named DRX (Discontinuous Reception) to save UE’s (User Equipment) energy consumption in LTE (Long Term Evolution). The DRX allow an UE to stop monitoring PDCCH (Physical Downlink Control CHannel) on a CC (Component Carriers) during some periods of the operation time. Obviously, the duration and the frequency of these non-monitoring periods are important parameters that can significantly impact the ES (Energy Saving) efficiency and the performance of applications running on the CC. In Release 9, 3GPP introduces an advanced technology named CA (Carrier Aggregation) for LTE-Advanced to achieve higher bandwidth and throughput: the UE may operate over up to 5 CCs. The conventional DRX operations are no longer appropriated in the CA case: applying the same DRX configuration for all the CCs is neither performance-optimal nor energy-efficient if applications with different QoS requirements operating simultaneously on the CCs in realistic environment. A DRX mechanism by taking both applications’ QoS requirement and CA into account to achieve reasonable ES might be an optimal choice. In this paper, based on the survey of various conventional DRX energy saving protocols in LTE networks, we propose a simple but efficient application aware DRX mechanism to optimize the performance in LTE-Advanced networks with CA consideration. The simulation results verify that the ES efficiency is conditioned to the fulfillment of the DRX parameters, and our proposed optimal scheme can significantly improve energy saving efficiency as compared to the conventional DRX mechanism.     

Energy Saving Mechanism with a Route Prediction Based Intra-handover in LTE Networks

Long term evolution standard employs the discontinuous reception (DRX) technology to help user equipment (UE) in energy saving. After the UE received nothing from the base station for a predefined time span, it turns off the radio frequency module to enter sleep mode for energy saving. An UE may fail to handover or lost connection for late handover in case it enters sleep mode before handover and missed the optimal handover timing, therefore results in data loss. This paper proposes an energy saving mechanism with a prediction based intra-handover which predicts the next target handover base station and the optimal handover time according to the historical path data kept in a database. The UE would check whether the next sleep mode outlast the handover time point before entering sleep mode to reduce power consumption for handover failure caused by the long DRX cycle and base station reselection. Simulation results show that the DRX mechanism helps reduce power consumption of UE by 90–95 % over the conventional one more than 7 % handover failures. The energy saving mechanism combined with route prediction leads to 22 % more energy saving while cutting handover failures to 5 %.

     

Efficient performance analysis of newly proposed sleep-mode mechanisms for IEEE 802.16m in case of correlated downlink traffic

There is a considerable interest nowadays in improving energy efficiency of wireless telecommunications. The sleep-mode mechanism in WiMAX (IEEE 802.16) and the discontinuous reception (DRX) mechanism of LTE are prime examples of energy saving measures. Recently, Samsung proposed some modifications on the sleep-mode mechanism, scheduled to appear in the forthcoming IEEE 802.16m standard, aimed at minimizing the signaling overhead. In this work, we present a performance analysis of this proposal and clarify the differences with the standard mechanism included in IEEE 802.16e. We also propose some special algorithms aimed at reducing the computational complexity of the analysis.     

Accurate Modeling of the DRX Mechanism with Predetermined DRX Cycles Based on the 3GPP LTE Standard

In Long Term Evolution-Advanced (LTE-A), the Discontinuous Reception (DRX) mechanism conserves the power of a User Equipment (UE) by monitoring the UE’s downlink channels for a specific period and turning off the UE’s radio when no packets arrive during the period. There has been heated discussion in previous studies, but most previous models of DRX operation are partially inconsistent with the LTE-A specifications. The reason is that the previous models hold the assumption that a new DRX cycle starts after an expiration of a drx-InactivityTimer or a period of continuous reception. This assumption causes undetermined DRX cycles and fixed-length sleep time in a UE in a DRX mechanism. However, the drx-InactivityTimer expiration can occur at any instant within a DRX cycle, which causes the variable-length sleep time. In this paper, we first propose a novel analytical model fitting for the specification DRX mechanism by using a semi-Markov process. Two key performance indicators affected by the DRX mechanism, the power saving factor and the average buffering delay of radio-off periods, are derived. We also prove the feasibility of the proposed model with stability analysis. Finally, the analytical results are validated against the simulation results and show the effects of different DRX configurations for the Poisson arrival process.     

Modeling UMTS Power Saving with Bursty Packet Data Traffic

The universal mobile telecommunications system (UMTS) utilizes the discontinuous reception (DRX) mechanism to reduce the power consumption of mobile stations (MSs). DRX permits an idle MS to power off the radio receiver for a predefined sleep period and then wake up to receive the next paging message. The sleep/wake-up scheduling of each MS is determined by two DRX parameters: the inactivity timer threshold and the DRX cycle. In the literature, analytic and simulation models have been developed to study the DRX performance mainly for Poisson traffic. In this paper, we propose a novel semi-Markov process to model the UMTS DRX with bursty packet data traffic. The analytic results are validated against simulation experiments. We investigate the effects of the two DRX parameters on output measures including the power saving factor and the mean packet waiting time. Our study provides inactivity timer and DRX cycle value selection guidelines for various packet traffic patterns.     

DRX mechanism for power saving in lte - [topics in radio communications]

Enhanced discontinuous reception mode is supported in long term evolution of 3GPP standards to conserve the mobile terminal?s battery power. Furthermore, there are additional advantages in using DRX, such as over-the-air resource saving on both the uplink and downlink to increase overall system capacity. One of the enhancements over 3G wireless systems is that in LTE DRX mode can be enabled even when the user equipment is registered with the evolved node-B. However, there is a need to optimize the DRX parameters, so as to maximize power saving without incurring network re-entry and packet delay. In particular, care should be exercised for real-time services. In this article the power saving methods in both network attached and network idle modes as outlined in LTE are explained. The optimum criteria to select the DRX mode are defined for different applications. Analytical/simulation results are presented to show the power saving/connection reestablishment and packet delay.     

Stochastic modeling for energy efficiency in modified directional discontinuous reception for LTE-5G networks

Fifth-generation (5G) networks deal with high-frequency data rates, ultra-low latency, more reliability, massive network capacity, more availability, and a more uniform user experience. To validate the high-frequency rates, 5G networks engage beam searching operation. By adopting a beam searching state between the short and long sleep, one can reduce the system's delay. The energy consumption of user equipment (UE) in 5G networks is much higher than in the 4G networks. To reduce the energy consumption and increase the energy saving in UE, Long-Term Evolution (LTE)-5G networks adopt the discontinuous reception (DRX) scheme with a fixed number of short sleep. LTE-DRX without beam search operation (i.e., beam alignment) cannot work in 5G networks. Hence, keeping this scenario in mind, we have modeled a new modified directional discontinuous reception (MD-DRX) mechanism for LTE-5G networks. The MD-DRX mechanism captures the behavior of a beam searching, an inactive, an active, a long sleep, an ON, and a short sleep states. The short sleep state consists of a maximum $M$ short sleep. To get the optimal energy saving and energy consumption (i.e., energy efficiency) from the MD-DRX mechanism, it is required to check the system's throughput. The trade-off between energy saving/energy consumption and throughput will provide the system's optimal energy saving and optimal energy consumption. In this paper, we have obtained the system's optimal energy saving and throughput by optimizing the maximum short sleep and short sleep duration. To get the energy efficiency for LTE-5G networks, the trade-off between average energy consumption/energy saving and throughput is shown.     

非连续接收机制及其提升算法标准化进展综述

近些年来,通信技术迅猛发展。新兴的技术不仅带来了更好的性能,同时也带来了更大的功耗。与此同时,用户终端呈现出小型化、便携化的特征,这使得用户终端无法携带大容量的电池,进而导致用户终端的续航性能变差,对用户体验产生了很大的负面影响。因此,非连续接收这一节能机制在最近的标准化进程中受到了很大的关注。很多组织和机构在提升该机制的性能方面提出了自己的想法和方案。本文将对已有的非连续接收机制以及相关的提升方案做一简要介绍和分析。