Performance analysis of the IEEE 802.16e sleep mode for correlated downlink traffic

In this paper, we evaluate the performance of the IEEE 802.16e sleep mode mechanism in wireless access networks. This mechanism reduces the energy consumption of a mobile station (MS) by allowing it to turn off its radio interface (sleep mode) when there is no traffic present at its serving base station (BS). After a sleep period expires, the MS briefly checks the BS for data packets and switches off for the duration of another sleep period if none are available. Specifically for IEEE 802.16e, each additional sleep period doubles in length, up to a certain maximum. Clearly, the sleep mode mechanism can extend the battery life of the MS considerably, but also increases the delay at the BS buffer. For the performance analysis, we use a discrete-time queueing model with general service times and multiple server vacations. The vacations represent the sleep periods and have a length depending on the number of preceding vacations. Unlike previous studies, we take the (short-range) traffic correlation into account by assuming a D-BMAP arrival process, i.e. the distribution of the number of packet arrivals per slot is modulated by the transitions in a Markov chain with N background states. As results, we obtain the distribution of the number of packets in the queue at various sets of time epochs, the distribution of the packet delay and the antenna activity rate. We apply these results to the IEEE 802.16e sleep mode mechanism with correlated downlink traffic. By means of some examples, we show the influence of both the configuration parameters and the traffic correlation on the delay and the energy consumption.     

基于IEEE802．16e睡眠模式的研究

IEEE802.16e标准是支持终端移动性的无线城域网接人标准.由于移动终端是由电池供电的,而休眠模式作为其必备功能,能有效管理其有限的电池容量,延长其单次充电使用时间.首先介绍了IEEE802.16e标准建议的睡眠模式,然后通过建立马尔可夫链模型对睡眠模式下的平均能量消耗及平均包延迟进行分析,最后NS2工具对分析结果进行NS2仿真和讨论.     

IEEE 802.16e/m energy‐efficient sleep‐mode operation with delay limitation in multibroadcast services

Mobile Worldwide Interoperability for Microwave Access networks usually provide flexible sleep‐mode operations that allow mobile stations to conserve energy during sleep or active mode. For example, the IEEE 802.16e/m standard presents three power‐saving classes that can be associated with different types of network connections to decrease the power consumption of mobile stations. However, previous studies failed to fully use the sleep‐mode features to save energy of a mobile station while simultaneously maintaining unicast and multicast/broadcast connections. This study proposes an energy‐efficient packet scheduling algorithm for both multicast and broadcast services that does not violate the QoS requirements of real‐time connections. The proposed activity aggregation selection mechanism approach can minimize total power consumption of mobile stations in one cell and simultaneously satisfy the QoS of real‐time connections. This method improves energy efficiency for IEEE 802.16e/m and the activity aggregation selection mechanism approach can optimize sleeping mode features to save the energy of mobile stations with overlapping connection packets The simulations in this study verified the proposed approach.Copyright © 2012 John Wiley & Sons, Ltd.     

Design of the QoS framework for the IEEE 802.16 mesh networks

IEEE 802.16 (WiMax) technology is designed to support broadband speeds over wireless networks for the coming era of broadband wireless access (BWA). IEEE 802.16 is expected to provide transmission of high‐rate and high‐volume multimedia data streams for fixed and mobile applications. As an extension of point‐to‐multipoint (PMP) configuration, the IEEE 802.16 mesh mode provides a quicker and more flexible approach for network deployment. Multimedia networking requires quality‐of‐service (QoS) support, which demands elaborate mechanisms in addition to the four service types defined in the specification. By examining standard centralized and distributed scheduling/routing schemes in the mesh mode from QoS aspect, a BS‐controlled and delay‐sensitive scheduling/routing scheme is proposed in the paper. Associate mechanisms including admission control, flow setup and link state monitoring are also proposed. Integration of the proposed mechanisms is presented as a complete QoS framework. Simulation study has demonstrated that the average delay as well as the delay jitters per hop in the proposed scheme is smaller than that of the distributed scheme and much smaller than that of the centralized scheme. Furthermore, proposed mechanisms can also achieve higher throughput than the contrasts and generate much smaller signaling overhead, making the proposed framework a promising scheme for multimedia support in the IEEE 802.16 mesh network. Copyright © 2009 John Wiley & Sons, Ltd.     

Performance analysis of the IEEE 802.16e power management for the initiations of awakening

To increase battery life in IEEE 802.16e systems, it is essential to efficiently manage energy in mobile stations. The sleep-mode operation in power management helps to increase the life of a station by saving energy consumption. In power management, there are two important performance metrics energy consumption and the response delay of awakening medium access control (MAC) service data unit (SDU). While in a base station (BS) initiation of awakening, the two performance metrics should be simultaneously considered, in a mobile subscriber station (MSS) initiation of awakening, the response delay is not considered because it is self-operational. There performance metrics are affected by the minimum sleep interval (Tmin), the maximum sleep interval (Tmax), and the average interarrival time of awakening MAC SDUs (TI) during sleep-mode operation. Therefore, it is imperative to evaluate the two initiations of awakening depending on TI. To reach a fuller understanding of the performance, this paper shows an analytical mode and simulations results for the standard sleep-mode operation in the IEEE 802.16e MAC.     

支持WiMAX节点灵活休眠的两阶段可靠多播策略

节能是无线网络的一个重要课题.针对IEEE 802.16e标准第2类节能模型中监听窗口长度固定会导致一些空闲移动站因得不到及时休眠而浪费能量这一不足,该文提出"两阶段可靠多播策略",让基站在第1阶段多播数据包,在第2阶段对第1阶段丢失的数据包进行网络编码并重播.该策略让移动站一旦空闲就进入休眠,实现了时延约束下数据包的可靠传递.仿真试验表明,该策略可以降低能耗,且移动站的占空比、能耗、吞吐率、丢包率等指标均优于传统的重传与确认方案.     

Delay versus energy consumption of the IEEE 802.16e sleep-mode mechanism

We propose a discrete-time queueing model for the evaluation of the IEEE 802.16e sleep-mode mechanism of Power Saving Class (PSC) I in wireless access networks. Contrary to previous studies, we model the downlink traffic by means of a Discrete Batch Markov Arrival Process (D-BMAP) with Ν phases, which allows to take traffic correlation into account. The tradeoff between energy saving and increased packet delay is discussed. In many situations, the sleep-mode performance improves for heavily correlated traffic. Also, when compared to other strategies, the exponential sleep-period update strategy of PSC I may not always be the best.     

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.     

Enhanced power saving through increasing unavailability interval in the IEEE 802.16e systems

The power saving mechanisms of the current IEEE 802.16e system are designed to take no consideration of the harmonization between power saving classes (PSCs) I and II. Using the IEEE 802.16e standard as a basis, we propose a dynamic power saving mechanism that increases unavailability interval when a mobile station (MS) uses PSCs. The proposed mechanism adjusts the timing of the sleep window of PSC I to maximize the unavailability interval of the MSs. As a result, the proposed scheme achieves power saving of the MSs. Through numerical analysis and simulations, we show that the proposed mechanism can reduce the power consumption of the MSs considerably compared with conventional mechanisms.     

Scheduled power-saving mechanism to minimize energy consumption in IEEE 802.16e systems

A Mobile Station in IEEE 802.16e operates power management using sleep-mode operation with one or more connections supporting several applications. After all of the connections of an MS transit into the sleep state, the MS powers down and then goes into an unavailable state without communicating with the serving Base Station. To improve energy conservation, this letter proposes a new Scheduled Power-Saving Mechanism, which schedules sleep-mode operations for connections, which newly initiate sleep-mode, by controlling operating parameters, such as the minimum sleep interval (Tmin) and the maximum sleep interval (Tmax), and the initiation time of sleepmode operations of low Quality of Service (QoS) connections. Performance results show that the proposed mechanism can reduce the available state of an MS through this scheduling, and thus achieve better energy conservation of the MS than the standard mechanism.     

Delay constrained uplink scheduling policy for rtPS/ertPS service in IEEE 802.16e BWA systems

WiMAX is a promising broadband wireless networking technology and is expected to take the place of broadband access solutions such as DSL and cable. Owing to its superior support in mobility, it is expected to provide integrated voice and data service to realize broadband mobile computing. In order to reach better quality‐of‐service (QoS) requirements for real‐time applications, the IEEE 802.16e standard defines five different services among traffic categories with different multimedia requirements. However, the problem of choosing the right set of medium access control parameters and packet scheduling policy to provide strict QoS guaranteed in IEEE 802.16e Broadband Wireless Access (BWA) systems remains unsolved and left as an open issue. In this paper, we propose a novel polling‐based uplink packet scheduling policy for real‐time Polling Service and extended real‐time Polling Service (rtPS/ertPS) traffic to support real‐time applications, with strict delay requirements, such as variable bit rate (VBR) traffic in IEEE 802.16e BWA systems. The proposed transmit‐permission policy can derive sufficient conditions such that all the rtPS/ertPS sources satisfy their time constraints to provide deterministic QoS guarantees. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design provides a good quality performance in the IEEE 802.16e BWA systems. Copyright © 2008 John Wiley & Sons, Ltd.     

Adaptive load‐balancing association handoff approach for increasing utilization and improving GoS in mobile WiMAX networks

The IEEE 802.16e standard is thus proposed for supporting high data rate and dynamic mobility in WiMAX. IEEE 802.16e specifies the association handoff mechanism in the MAC layer, i.e., providing contention‐free‐based initial ranging, and thus mobile stations can perform the initial ranging early during the handoff period. An MS executing the association handoff during a scan duration is disallowed to send/receive any packets to/from the serving BS. IEEE 802.16e suffers from not determining a precision scan duration period because of losing the transmission opportunity or the response status of the received ranging response (RNG‐RSP) message. Although the MS can set a longer scan duration to complete the initial ranging procedure, it significantly degrades handoff delay and delay jitter of real‐time service flows. In addition, most handoff studies seldom considered balancing traffic load among neighbor base stations (BSs). This paper thus proposes an efficient Adaptive Load‐balancing Association handoff approach (ALA) consisting of two phases: (1) the Adaptive Association Handoff phase (AAH) and (2) the Predictive Direction‐based Load Balancing phase (PDLB), to overcome above mentioned problems. AAH proposes an adaptive re‐association mechanism to reduce lost synchronizations, and thus improve the grade of service. PDLB adopts the Polynomial Regression‐based RSS prediction algorithm to accurately predict the moving direction of mobile nodes. Numerical results demonstrate that ALA significantly outperform IEEE 802.16e and others in average handoff delay, number of handoffs, dropping probability, GoS, network utilization, and number of lost synchronizations. Copyright © 2011 John Wiley & Sons, Ltd.     

IEEE 802.16和WiMax的组网技术

如何提高网络资源利用率和网络传输效率是无线通信领域面临的难题。作为宽带无线接入系统的标准，IEEE802，16在物理层采用正交频分复用技术和灵活的编码调制方式采提高传输速度和性能；在MAC层采用预约与竞争相结合的调度机制，以连接、服务流等与服务质量（QoS）相关的概念为基础。在入网与初始化、帧结构设计上优化设计，提高网络吞吐量，降低网络时延，使网络配置更加灵活。WiMAX基于IEEE802．16技术标准。采用点对多点（PMP）方式实现灵活组网，是宽带无线接入系统的典型血用技术。     

Performance analysis of bandwidth requests under unicast, multicast and broadcast pollings in IEEE 802.16d/e

In the polling mode in IEEE 802.16d/e, one of three modes: unicast, multicast and broadcast pollings, is used to reserve bandwidth for data transmission. In the unicast polling, the BS polls each individual MS to allow to transmit a bandwidth request packet, while in the multicast and broadcast pollings, the truncated binary exponential backoff (TBEB) mechanism is adopted as a contention resolution among mobile stations (MSs) in a multicast or broadcast group. This paper investigates the delay of bandwidth requests in the unicast, multicast and broadcast pollings, by deriving the delay distribution of the unicast polling and the TBEB by means of analytical methods. We consider an error-free channel as well as an error-prone channel with i.i.d. constant packet error rate per frame. Furthermore, we find the utilization of transmission opportunity to see efficiency of the bandwidth in the TBEB. Performance evaluations are provided to show that analytical results are well-matched with simulations. By the numerical results, we can find the optimal parameters such as the initial backoff window size of the TBEB and the number of transmission opportunities (or slots) satisfying quality of service (QoS) requirement on delay and loss, and thus we can determine which scheme is better than others depending on the probability of a request arrival during one frame. Numerical examples address that the TBEB performs better than the unicast polling for light traffic loads and vice versa for heavy traffic loads. Also, it is shown that the multicast polling has better performance than the broadcast polling in the sense of shorter delay, lower loss probability and higher utilization of transmission opportunity.     

Load-Based Power Saving in IEEE 802.16j Multi-Hop Relay Networks

In this paper, our previous work of Load-Based Power Saving (LBPS) for energy saving at the user side is extended to support integrated sleep scheduling for BS, RS, and MSS in the IEEE 802.16j Multi-Hop Relay Network. Topology-dependent time frame structure is adopted in our design to reduce the transmission delay in the relay network, in which the number of relay zone (for transmission over the relay link) depends on the hop count of RS in the network. Focused on non-real-time traffic, two LBPS schemes, namely LBPS-Aggr-MR and LBPS-Merge-MR, are proposed. Simulation study shows the proposed LBPS schemes significantly outperform the standard Type I PSC in terms of power saving efficiency.     

Cross-layer cut-through switching mechanism for IEEE 802.16d/e wireless networks

This paper proposes a fast cross-layer cut-through switching mechanism (CCSM) for supporting media access control (MAC) layer packet switching in IEEE 802.16-based broadband wireless access (BWA) networks. The local traffic, which means subscriber stations (SSs) communicating with each other within the cell, can be switched via the MAC layer without involving the network layer. The average access delay of request from SSs is studied and analyzed in this paper. Finally, the simulation and numerical results show that the performance of CCSM is superior to that of the legacy IEEE 802.16d/e protocol.     

State transition reduction for sleep scheduling in IEEE 802.16e mobile subscriber stations

IEEE 802.16e devices may enter sleep mode to conserve energy. There has been some work studying how to schedule device’s packet transmissions to maximize the device’s sleep period while meeting associated QoS (quality of service) requirements. This paper proposes two schemes that attempt to save more energy for a given sleep schedule by accelerating or deferring scheduled packet transmissions with the intention to further reduce the frequency of transitions from sleep to active modes (states). Performance evaluation results indicate that the proposed schemes effectively reduce state transitions when compared with existing sleep scheduling schemes. Packet delays may also be improved in case of accelerating packet transmissions.     

Performance of packet voice transmission using IEEE 802.16 protocol

The IEEE 802.16 standard defines three types of scheduling services for supporting real-time traffic, unsolicited grant service (UGS), real-time polling service (rtPS), and extended real-time polling service (ertPS). In the UGS service, the base station (BS) offers a fixed amount of bandwidth to a subscriber station (SS) periodically, and the SS does not have to make any explicit bandwidth requests. The bandwidth allocation in the rtPS service is updated periodically in the way that the BS periodically polls the SS, which makes a bandwidth request at the specified uplink time slots and receives a bandwidth grant in the following downlink subframe. In the ertPS service, the BS keeps offering the same amount of bandwidth to the SS unless explicitly requested by the SS. The SS makes a bandwidth request only if its required transmission rate changes. In this article we study the performance of voice packet transmissions and BS resource utilization using the three types of scheduling services in IEEE 802.16-based backhaul networks, where each SS forwards packets for a number of voice connections. Our results demonstrate that while the UGS service achieves the best latency performance, the rtPS service can more efficiently utilize the BS resource and flexibly trade-off between packet transmission performance and BS resource allocation efficiency; and appropriately choosing the MAC frame size is important in both the rtPS and ertPS services to reduce packet transmission delay and loss rate     

一种分级WFQ的宽带无线接入系统QoS架构

文章介绍了加权公平排队(WFQ)分组调度算法和IEEE 802 16的QoS架构.在此基础上,文章结合分级WFQ分组调度算法和IEEE 802 16协议中所提供的控制机制提出了一种适合于BWA系统的QoS架构.该架构充分利用IEEE 802.16提供的控制机制,结合分级WFQ公平队列调度算法,在主动授予业务(UGS)、实时轮询业务(rtS)、非实时轮询业务(nrtPS)和尽力传输业务(BE)之间公平分配带宽,并保证各种业务的QoS特性,完成了在IEEE 802 16协议中留给用户自己定义的调度策略.     

Performance Evaluation of IEEE 802.15.4 CSMA/CA Scheme Adopting a Modified LIB Model

Since the successful release of the IEEE 802.15.4 standard, a great convenience is offered to applications in low-power and low-rate wireless sensor networks (WSNs) which almost touch upon all aspects in our surrounding circumstances. For time-critical applications, we use a modified Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism called Linear Increase Backoff (LIB) to enhance the performance of packet delay, but not compromise the metrics of energy efficiency and throughput. An accurate and comprehensive Markov model is used to analyze the characteristics of our LIB scheme predicting packet delay, energy consumption and throughput of unsaturated, unacknowledged IEEE 802.15.4 networks in which the unsaturated state is dependent on the traffic condition rather than the depiction by a predetermined length. Simulation results are consistent with the predictions of this model. We also compare the performance of LIB with that of several mechanisms according to the optimal parameters selected from operating point, and find that packet delay is obviously superior to that of other schemes, while energy efficiency and throughput are superior to others for large number of nodes and high traffic arrivals.