Performance Evaluation of Sleep Mode on Power Saving in WiMAX IEEE 802.16m and LTE DRX

Power saving represents a vital role in mobile communications networks such as IEEE 802.16m and LTE. Modern user equipment (UE_s) require high data rates and low power consumption. It is found that arranging sleep mode mechanisms ensures UE battery longer lifetime. In this paper, different sleep mode mechanisms are investigated for both IEEE 802.16m and LTE networks. The analyses are based on Markov and Semi-Markov chains. It is focused on the determination of UE transition state. Web traffic model parameters were considered in MATLAB simulation and a comparison assessment was conducted between WiMAX IEEE 802.16m and LTE DRX. It was found that LTE DRX sleep mode provides more power saving than WiMAX IEEE 802.16m sleep mode. The study is now implemented for 5G networks with encouraging results.     

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.     

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。     

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。     

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.     

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.     

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 %.

     

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。     

Improvement in DRX Power Saving for Non‐real‐time Traffic in LTE

A discontinuous reception (DRX) operation is included in the Long Term Evolution (LTE) system to achieve power saving and prolonged battery life of the user equipment. An improvement in DRX power saving usually leads to a potential increase in the packet delay. An optimum DRX configuration depends on the current traffic, which is not easy to estimate accurately, particularly for non‐real‐time applications. In this paper, we propose a novel way to vary the DRX cycle length, avoiding a continuous estimation of the data traffic when only non‐real‐time applications are running with no active real‐time applications. Because a small delay in non‐real‐time traffic does not essentially impact the user's experience adversely, we deliberately allow a limited amount of delay in our proposal to attain a significant improvement in power saving. Our proposal also improves the delay in service resumption after a long period of inactivity. We use a stochastic analysis assuming an M/G/1 queue to validate this improvement.     

LTE中基于上行控制信息的调度策略分析简

LTE是3G之后一个很有前景的移动通信技术。LTE中,网络基于终端上报的上行控制信息（即CQI、RI、PMI）进行调度。终端经过测试后发现现网中网络存在多种调度策略,如完全按终端上报信息调度、完全按自己的策略调度。经分析,建议网络和终端都有自身的策略,两者相对独立,但上报或调度策略的目标是相同的,即在保证通信质量的前提下,提高数据吞吐量。     

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.     

5G终端空闲态节能方案分析

由于大带宽、大规模天线、高速率等新特性的引入,5G终端的能耗问题比4G终端更加严峻,成为影响5G网络用户体验的重要原因之一。3GPP标准化组织开展了与NR终端节能课题相关的研究,R16协议版本主要面向连接态下的终端节能优化,R17协议版本则主要面向空闲态终端节能优化。首先分析了空闲态下的终端节能问题,同时与LTE终端能耗进行对比。针对寻呼检测和时频跟踪过程的能耗问题提出了节能优化解决方案,进行了节能增益分析,该方案可以降低5G终端的能耗,为后续5G商用终端空闲态的节能技术指明了方向。     

A Secure Relay-Assisted Handover Protocol for Proxy Mobile IPv6 in 3GPP LTE Systems

The LTE (Long Term Evolution) technologies defined by 3GPP is the last step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile telephone networks. Mobility management for supporting seamless handover is the key issue for the next generation wireless communication networks. The evolved packet core (EPC) standard adopts the proxy mobile IPv6 protocol (PMIPv6) to provide the mobility mechanisms. However, the PMIPv6 still suffers the high handoff delay and the large packet lost. Our protocol provides a new secure handover protocol to reduce handoff delay and packet lost with the assistance of relay nodes over LTE networks. In this paper, we consider the security issue when selecting relay nodes during the handoff procedure. During the relay node discovery, we extend the access network discovery and selection function (ANDSF) in 3GPP specifications to help mobile station or UE to obtain the information of relay nodes. With the aid of the relay nodes, the mobile station or UE performs the pre-handover procedure, including the security operation and the proxy binding update to significantly reduce the handover latency and packet loss. The simulation results illustrate that our proposed protocol actually achieves the performance improvements in the handoff delay time and the packet loss rate.     

On the eNB‐based energy‐saving cooperation techniques for LTE access networks

Energy efficiency is one of the top priorities for future cellular networks, which could be accomplished by implementing cooperative mechanisms. In this paper, we propose three evolved node B (eNB)‐centric energy‐saving cooperation techniques for long‐term evolution (LTE) systems. These techniques, named as intra‐network, inter‐network, and joint cooperation, involve traffic‐aware intelligent cooperation among eNBs belonging to the same or different networks. Our proposed techniques dynamically reconfigure LTE access networks in real time utilizing less number of active eNBs and thus, achieve energy savings. In addition, these techniques are distributed and self‐organizing in nature. Analytical models for evaluating switching dynamics of eNBs under these cooperation mechanisms are also formulated. We thoroughly investigate the proposed system under different numbers of cooperating networks, traffic scenarios, eNB power profiles, and their switching thresholds. Optimal energy savings while maintaining quality of service is also evaluated. Results indicate a significant reduction in network energy consumption. System performance in terms of network capacity utilization, switching statistics, additional transmit power, and eNB sleeping patterns is also investigated. Finally, a comprehensive comparison with other works is provided for further validation. Copyright © 2013 John Wiley & Sons, Ltd.     

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。     

Power consumption analysis of video streaming in 4G LTE networks

Video streaming, one of the most popular technologies for online video playback, has already been applied to 4G LTE networks. Previous work has been devoted to understanding the power consumption in general 4G LTE networks, while it is still unclear how the online video streaming makes impact on the power performance of mobile devices. Inspired by this, this paper investigates the relationship between the mobile device’s power performance characteristics and the behaviours of video streaming in 4G LTE networks. There are many natural issues/questions that are clearly interesting and important, while it is non-trivial to answer these issues/questions exactly (e.g., where is the energy saving room? how much is it?). To address a series of issues like the above, we formulate our energy models together with an algorithm that can assist our analysis. Particularly, we design a systematic platform, and conduct a comprehensive and also deep analysis on the power consumption of video streaming in 4G LTE networks. Our experiments reveal us a series of valuable findings—the saving room in the network part is large (from 41.86 to 69.62%), the number of RRC tails and the transmission pattern could be promising for optimizing the power consumption, for example.     

Self-Similar Traffic in G/M/1 Queue Defined by the Weibull Distribution

The work considers a queuing system of the G/M/1 type that simulates service of self-similar traffic in a NodeB (e-NodeB) base station of a mobile operator. The feature of quality of service (QoS) characteristics estimation process for the self-similar traffic defined by the Weibull distribution is the solution based on the Laplace–Stieltjes transformation. The Laplace transformation for an infinite number of items under the Weibull distribution condition was found. It was shown that this series was equiconvergent to some convergence domain. The following QoS characteristics were obtained for the self-similar traffic: the average amount of time that a request spends in the system; the average number of requests waiting in the queue and the average queue length. The obtained results allowed to consider the real values of traffic serviced by a NodeB (e-NodeB) for their optimal deployment over a covered territory at the stage of frequency planning and operation of the 3G/UMTS and 4G/LTE networks.     

一种面向B5G初始接入过程的增强型波束管理机制设计

波束管理是毫米波通信的重要研究内容,5G NR（New Radio）协议中已完整设计了用户在初始接入和连接状态下与基站确定最佳通信波束的流程,然而B5G(Beyond Fifth Generation)场景将使用52.6 GHz以上甚至更高的通信频率,需要更大规模的天线单元对抗路损,导致波束管理在初始接入过程中的信令开销和时延急剧增加。为此,在5G NR协议现有框架的基础上,针对52.6 GHz以上的高频段重新设计了一种专用于波束扫描的信号块（Beam Sweeping Block,BSB）,并提出一种两阶段增强型波束管理机制,用于在初始接入过程中快速确定用户和基站的最佳通信波束,进而完成同步和小区搜索。仿真结果表明,相对于NR中现有的波束管理机制,所提出的增强型波束管理方案可在保证接入性能的前提下,大幅降低初始接入时延。     

Requirements on Satellite Access Node and User Equipment for Non-Terrestrial Networks in 5G New Radio of 3GPP Release-17

For the first time, 3GPP considered in Release-17 the introduction of mobile satellite service (MSS) frequency bands for 3GPP user equipment (UE) direct connectivity with satellites and had to consider the coexistence in adjacent bands with terrestrial networks (TNs). This paper will further explain the most challenging and the main surprising outcomes of this work, which opened new market opportunities for both terrestrial and nonterrestrial stakeholders. 5G New Radio nonterrestrial networks (NTNs) for satellite communications are representing a major breakthrough in the history of telecommunication for the capability of reuniting two different types of services, that is, terrestrial and nonterrestrial, by reusing the same waveform and potentially the same type of terminal. One of the major conclusions of the 5G NR NTN 3GPP work in Release-17 was that NTN UE could reuse the current requirements of the TN UE. For this reason, the same terminal can connect to both TNs and to nonterrestrial satellite constellations. Consequently, the market is not fragmented and therefore there will be a real opportunity for both terrestrial and satellite operators to increase the coverage and the quality of the service all over the world. This is one of the most important breakthroughs that 3GPP Release-17 work was able to justify because it clearly shows that satellite connectivity using 5G NR technology is not only for dedicated satellite 5G NR UE with a higher power class. On the other hand, the 3GPP work also shows that the satellite connectivity does not require a dedicated satellite waveform, because 5G NR waveform based on CP-OFDM (for downlink) and DFT-s-OFDM (for uplink) is sufficient. Another important finding is that TN can coexist with NTN on adjacent channels with relaxed ACIR requirements for the tested simulation scenarios. In fact, the satellite 5G NR requirements are lower when compared with terrestrial base station (BS) requirements from previous 3GPP releases. The satellite ecosystem tremendously changed after these findings, and both satellite and terrestrial stakeholders now see a potential market opportunity.     

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.