IEEE 802.16/WiMAX-based broadband wireless access and its application for telemedicine/e-health services

In this article we investigate the application of IEEE 802.16-based broadband wireless access (BWA) technology to telemedicine services and the related protocol engineering issues. An overview of the different evolutions of the IEEE 802.16 standard is presented and some open research issues are identified. A survey on radio resource management, traffic scheduling, and admission control mechanisms proposed for IEEE 802.16/WiMAX systems is also provided. A qualitative comparison between third-generation wireless systems and the IEEE 802.16/WiMAX technology is given. A survey on telemedicine services using traditional wireless systems is presented. The advantages of using IEEE 802.16/WiMAX technology over traditional wireless systems, as well as the related design issues and approaches are discussed. To this end, we present a bandwidth allocation and admission control algorithm for IEEE 802.16-based BWA designed specifically for wireless telemedicine/e-health services. This algorithm aims at maximizing the utilization of the radio resources while considering the quality of service requirements for telemedicine traffic. Some performance evaluation results for this scheme are obtained by simulations     

Centralized Resource Allocation for Multimedia Traffic in IEEE 802.16 Mesh Networks

The IEEE 802.16 standard provides a high degree of flexibility for setting up and operating wireless broadband networks in metropolitan environments. The standard supports numerous capabilities, including mesh topologies and multimedia communications. In this paper, we study these two features by investigating how efficiently an IEEE 802.16 mesh network can treat distributed multimedia traffic by providing differentiated quality of service (QoS). A key component of the system is the ldquoenhanced frame registry tree schedulerrdquo (E-FRTS) that provides QoS-aware resource allocation using a tree structure to prepare the creation of time frames and reduce processing requirements at the beginning of each frame. Simulation results show that distributed multimedia traffic can be efficiently supported in mesh 802.16 networks, provided efficient scheduling and a reasonable number of hops.     

Queue-aware uplink bandwidth allocation and rate control for polling service in IEEE 802.16 broadband wireless networks

IEEE 802.16 standard defines the air interface specifications for broadband access in wireless metropolitan area networks. Although the medium access control signaling has been well-defined in the IEEE 802.16 specifications, resource management and scheduling, which are crucial components to guarantee quality of service performances, still remain as open issues. In this paper, we propose adaptive queue-aware uplink bandwidth allocation and rate control mechanisms in a subscriber station for polling service in IEEE 802.16 broadband wireless networks. While the bandwidth allocation mechanism adaptively allocates bandwidth for polling service in the presence of higher priority unsolicited grant service, the rate control mechanism dynamically limits the transmission rate for the connections under polling service. Both of these schemes exploit the queue status information to guarantee the desired quality of service (QoS) performance for polling service. We present a queuing analytical framework to analyze the proposed resource management model from which various performance measures for polling service in both steady and transient states can be obtained. We also analyze the performance of best-effort service in the presence of unsolicited grant service and polling service. The proposed analytical model would be useful for performance evaluation and engineering of radio resource management alternatives in a subscriber station so that the desired quality of service performances for polling service can be achieved. Analytical results are validated by simulations and typical numerical results are presented.     

IEEE 802.16 Mesh Schedulers: Issues and Design Challenges

IEEE 802.16 mesh mode defines three types of resource scheduling: coordinated centralized, coordinated distributed, and uncoordinated distributed. While the standard defines the required procedures and messages for each scheduler, it does not offer encouraging means to provide performance, reliability, or QoS. In this article we outline the issues of IEEE 802.16 mesh schedulers. We also survey representative proposals and qualitatively evaluate them against these issues. More critically, we identify key challenges that have not been addressed so far in the literature to motivate work in this area of research.     

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     

Resource Management and QoS Provisioning for Duplex Services in IEEE 802.16

Duplex services are multimedia services that requires good connectivity in both uplink and downlink such as VoIP, video conferencing and interactive gaming. A weak connection in either direction may cause degradation of performances and dissatisfaction of user experience. Most researchers do not consider this issue and treat resource allocations in uplink and downlink independently. For this reason, the conventional resource management schemes do not guarantee a good duplex connectivity. Generally, duplex schemes require some relation or information to be exchanged between uplink and downlink resource allocation processes. The existing duplex resource allocation schemes, however, have high complexity and do not adhere to the IEEE 802.16 standard. In this paper, we propose a duplex resource management scheme for IEEE 802.16 network to enhance the user experience and to improve the network performances. The proposed resource management scheme is a MAC layer function that co-relates the uplink and downlink allocation processes using a newly proposed duplex variable. Simulation studies show that the proposed scheme brings significant benefit to duplex services in the IEEE 802.16 networks and outperforms the conventional and existing schemes in terms of uplink and downlink transmission gap, QoS performances and fairness.     

An efficient scheduling scheme with diverse traffic demands in IEEE 802.16 networks

In IEEE 802.16 networks, a subscriber station (SS) could be a single mobile user, a residence house, or an office building providing Internet service for multiple customers. Considering the heterogeneity among SSs which have diverse traffic demands, in this paper, we introduce the weighted proportional fair (WPF) scheduling scheme for the Best Effort (BE) service in IEEE 802.16 networks to achieve the flexible and efficient resource allocation. We develop an analytical model to investigate the performance of WPF in terms of spectral efficiency, throughput, resource utilization, and fairness, where the Rayleigh fading channel and the adaptive modulation and coding (AMC) technique are considered. Extensive simulations are conducted to illustrate the efficiency of the WPF scheduling scheme and verify the accuracy of the analytical model. Copyright © 2009 John Wiley & Sons, Ltd.     

IEEE802.16中一种改进的跨层QoS调度架构设计

IEEE802委员会制定了一个解决“最后一公里”宽带无线城域网（WMAN）接入问题的全球统一标准,即IEEE802．16标准。它定义了支持多种业务类型的独立于具体物理层的MAC层和多个物理层。对于802．16系统的QoS保障,标准中详细规定了服务类别的划分以及系统的Qos框架和具体的信令交互机制,但没有规定具体的QoS调度算法,而是留给厂家设计。因此本文在IEEE802．16已有QoS调度架构的基础上,设计出一种改进的跨层QoS调度架构,并详细介绍了该构架下各功能模块的功能和具体实现方法。     

TCP-Aware Uplink Scheduling for IEEE 802.16

In IEEE 802.16 networks, a bandwidth request-grant mechanism is used to accommodate various QoS requirements of heterogeneous traffic. However, it may not be effective for TCP flows since (a) there is no strict QoS requirement in TCP traffic; and (b) it is difficult to estimate the amount of required bandwidth due to dynamic changes of the sending rate. In this letter, we propose a new uplink scheduling scheme for best-effort TCP traffic in IEEE 802.16 networks. The proposed scheme does not need any bandwidth request process for allocation. Instead, it estimates the amount of bandwidth required for a flow based on its current sending rate. Through simulation, we show that the proposed scheme is effective to allocate bandwidth for TCP flows     

QoS Differentiation for IEEE 802.16 WiMAX Mesh Networking

Recently IEEE 802.16 WiMAX has attracted a lot of attention in wireless networking research and applications. To enable a flexible and cost-effective deployment, mesh networking mode is defined in WiMAX standard. In this paper, we introduce a system model of WiMAX mesh networking with the focus on entry process, frame structure, centralized and distributed scheduling. The state-of-the-art WiMAX mesh networking research is reviewed. In addition, we propose an effective QoS differentiation scheme for the IEEE 802.16 WiMAX mesh networks. Both collocated scenario and general topology are theoretically analyzed and compared. Illustrative numerical examples are presented to demonstrate the effectiveness of the proposed strategy. The impact of key parameters on the performance is discussed for differentiating multiple classes of services. Several open issues are summarized as a guideline for future topics in WiMAX mesh networking research.     

Efficient routing and centralized scheduling algorithms for IEEE 802.16 Mesh Networks

An IEEE 802.16 wireless system can provide broadband wireless access to subscriber stations and operate in mesh mode. The communication between a subscriber station and a base station can pass through one or more intermediate subscriber stations. The IEEE 802.16 standard provides a centralized scheduling mechanism that supports contention‐free and resource‐guarantee transmission services in mesh mode. However, the corresponding algorithm to this schedule is quite primitive in the standard. In this paper, we propose a more efficient way to realize this schedule by maximizing channel utilization. Our designs are divided into two phases: routing and scheduling. First, a routing tree topology is constructed from a given mesh topology by our proposed tree construction algorithm. Secondly, we allocate channel resources to the edges in the routing tree by our proposed scheduling algorithm. To further support the quality‐of‐service schedule, we extend our designs by addressing some issues such as service class, admission control and fairness. Simulation results show the superiority of our proposed algorithms over others. Copyright © 2011 John Wiley & Sons, Ltd.     

Enabling collocated coexistence in IEEE 802.16 networks via perceived concurrency - [WiMAX update]

Multiple wireless interfaces (GSM, Wi-Fi, Bluetooth, FM, and GPS receiver, etc.) are being integrated into mobile devices. WiMAX, an IEEE802.16-based wireless access technology recently included in the IMT-2000 set of standards by ITU-R, will soon be added. Obstacles remain to operating these collocated radios concurrently, including interference and hardware conflicts due to congested spectrum allocation and component sharing with radio integration. In this article we provide a tutorial overview of today?s solutions to enable concurrent operation of multiple collocated radios in IEEE 802.16- based wireless networks with a focus on perceived concurrency: a MAC coordination approach. We then present three general design principles ? predictability, compressibility, and flexible scheduling ? with examples of standard features. It is anticipated that the next-generation IEEE 802.16 standards will be enhanced with new features such as explicit service setup, asynchronous operation, and collocated coexistence- aware scheduling.     

Scheduler for IEEE 802.16 networks

The IEEE 802.16 standard was designed to support real-time and bandwidth demanding applications with quality of service (QoS). Although the standard defines a QoS signaling framework and five service levels, scheduling disciplines for these service levels are unspecified. In this paper, we propose a scheduling scheme for the uplink traffic which is fully standard-compliant and can be easily implemented in the base station. Simulation results show that this scheme is able to meet the QoS requirements of the service flows.     

Robust QoS Control for Single Carrier PMP Mode IEEE 802.16 Systems

The IEEE 802.16 WirelessMAN standard provides a comprehensive quality-of-service (QoS) control structure to enable flow isolation and service differentiation over the common wireless network interface. By specifying a particular set of service parameters, the media access control (MAC) mechanisms defined in the standard are able to offer predefined QoS provisioning on a per-connection basis. However, the design of efficient, flexible, and yet robust MAC scheduling algorithms for such QoS provisioning still remains an open topic. This paper proposes a new QoS control scheme for single-carrier point-to-multipoint mode wireless metropolitan area network (WirelessMAN) systems, which enables the predefined service parameters to control the service provided to each uplink and downlink connection. By MAC-PHY cross-layer resource allocation, the proposed scheme is robust against particular wireless link degradation. Detailed simulation experiments are presented to study the performance and to validate the effectiveness of the proposed QoS control scheme.     

Dynamic frame partitioning scheme for IEEE 802.16 mesh networks

The IEEE 802.16 mesh network is a promising next generation wireless backbone network. In the network, the allocation of minislots is handled by centralized scheduling and distributed scheduling, which are independently exercised. However, the standard does not specify how the frame can be partitioned among its centralized and distributed schedulers. Through efficient partitioning that dynamically adapts the partitioning based on demand, network can support more user applications. Although a dynamic frame partitioning scheme to use Markov model has been studied, the dynamic frame partitioning method has not been fully investigated. This paper proposes two novel and general dynamic frame partitioning scheme for IEEE 802.16 mesh networks so that the minislot allocation can be more flexible and the utilization is increased. The two schemes respectively use GM(1,1)‐Markov model and Grey–Verhulst–Markov model to predict efficient partitions for future frames according to the minislot utilization in current frames. Our study indicates that the two proposed schemes outperform the scheme of using Markov model. Copyright © 2012 John Wiley & Sons, Ltd.     

Dynamic resource allocation in OFDMA wireless metropolitan area networks [Radio Resource Management and Protocol Engineering for IEEE 802.16]

In this article we present important resource allocation problems in IEEE 802.16 wireless metropolitan area networks employing orthogonal frequency division multiple access. We first highlight the unique aspects of these networks and identify challenges and opportunities provided by the physical and medium access control layers. Next, we concentrate on four interrelated resource allocation problems: dynamic subcarrier allocation, adaptive power allocation, admission control, and capacity planning. We describe solution techniques, provide preliminary results, and discuss open problems for future research     

Adaptive scheduling mechanism for IPTV over WiMAX IEEE 802.16j networks

A WiMAX technology is a very promising Broadband Wireless Access technology that is able to transmit different service types. This latter can have different constraints such as traffic rate, maximum latency, and tolerated jitter. The IEEE 802.16 Medium Access Control specifies five types of QoS classes: UGS, rtPS, ertPS, nrtPS, and BE. However, the IEEE 802.16 standard does not specify the scheduling algorithm to be used. Operators have the choice among many existing scheduling techniques. Also, they can propose their own scheduling algorithms. In this paper, we propose a scheduling strategy (Adaptive Weighted Round Robin, AWRR) for various Internet Protocol Television (IPTV) services traffic over 802.16j networks. Our scheme adapts dynamically the scheduler operation to according queue load and quality of service constraints. In particular, the proposed mechanism gives more priority to high definition television and standard definition television traffic by using two schedulers. The proposed scheduling algorithm has been simulated using the QualNet network simulator. The experimental results show that our scheduler schemes AWRR have a better performance than the traditional scheduling techniques for rtPS traffic, which allows ensuring QoS requirements for IPTV application. Copyright © 2012 John Wiley & Sons, Ltd.     

A novel routing algorithm in distributed IEEE 802.16 mesh networks

In this paper, we propose a novel distributed routing algorithm for IEEE 802.16/WiMax based mesh networks. Our algorithm aims at providing routes for traffic flows with minimum end-to-end delays. Based on the underlying IEEE802.16 standard distributed scheduling mechanism, our routing algorithm is incorporated into the medium access control (MAC) layer. Each node determines the next-hop nodes for the passing flows according to the scheduling information and attempts to forward packets in the very earliest slots. In addition, a loop cancelation mechanism is proposed to avoid being trapped in path loops and thus guarantees the accessibility of our algorithm. The simulation results show that our proposal can considerably reduce the delay of traffic flows and also achieve load balance to a certain degree.     

IEEE802.16技术标准最新进展

IEEE802.16m标准是IEEE802.16正在制定的最新标准.在简单介绍16m的研究背景、研究计划和主要需求的基础上,结合16m制定过程中最重要的几个文档,着重介绍了IEEE802.16m标准的最新进展.     

IEEE802.16中多媒体QoS保证机制的研究

首先分析了IEEE802.16四种业务类型的特点及QoS服务模型,对IEEE802.16的QoS机制和调度策略进行了深入的研究,并对相应的调度算法进行了分析。结果表明,IEEE802.16能够对实时业务提供较好的支持,同时维持其它业务的带宽在可接受的范围之内。