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.     

Cross-layer Based Delay-constraint Adaptive Polling for High Density Subscribers in IEEE 802.16 WiMAX Networks

The IEEE 802.16 standard (namely WiMAX) is proposed to support QoS-aware transmission of real-time service in Wireless Metropolitan Area Networks (WMANs). WiMAX also can operate as a wireless backbone, and then cooperates with WiFi to form a heterogeneous wireless network. Thus, hot spots of WiFi belonging to different WiMAX networks can communicate with each other. For achieving that a Base Station (BS) serves a large number of Subscriber Stations (SSs), WiMAX uses a centralized polling access mechanism instead of a random access mechanism. WiMAX thus avoids occurring access collisions but causes long polling delay under a high-density SSs situation. Consequently, IEEE 802.16 does not schedule real-time service (rtPS) while the BS is in multicast polling mode. This problem of long polling delay becomes worse when the BS serves high-density SSs, because the BS only polls some SSs or groups in every frame time. This paper thus proposes an adaptive polling approach with a cross-layer mechanism, which dynamically polls SSs among different polling modes while continuously supporting the rtPS service. The approach consists of two phases. The first phase adopts two hysteresises of number of SSs and residual bandwidth to determine the optimal polling mode for each connection. The second phase presents a novel QoS-aware rtPS service (QrtPS) that provides an Average Delay requirement instead of the Maximum Delay requirement to take over the rtPS service when a SS is polled by the multicast mode. Additionally, a cross-layer mechanism is proposed to achieve that the real-time applications can be sent with a high-quality or low-quality video codec when the SS is in unicast or multicast mode, respectively. Numerical results demonstrate that the proposed approach significantly outperforms IEEE 802.16 in average delay and network utilization. Furthermore, the collision probabilities of using different numbers of contention slots of an uplink subframe and different numbers of groups within a BS are evaluated for the multicast mode. The results meet the experiments.

Performance Evaluation of the IEEE 802.16 MAC for QoS Support

The IEEE 802.16 is a standard for broadband wireless communication in metropolitan area networks (MAN). To meet the QoS requirements of multimedia applications, the IEEE 802.16 standard provides four different scheduling services: unsolicited grant service (UGS), real-time polling service (rtPS), non-real-time polling service (nrtPS), and Best Effort (BE). The paper is aimed at verifying, via simulation, the effectiveness of rtPS, nrtPS, and BE (but UGS) in managing traffic generated by data and multimedia sources. Performance is assessed for an IEEE 802.16 wireless system working in point-to-multipoint (PMP) mode, with frequency division duplex (FDD), and with full-duplex subscriber stations (SSs). Our results show that the performance of the system, in terms of throughput and delay, depends on several factors. These include the frame duration, the mechanisms for requesting uplink bandwidth, and the offered load partitioning, i.e., the way traffic is distributed among SSs, connections within each SS, and traffic sources within each connection. The results also highlight that the rtPS scheduling service is a very robust scheduling service for meeting the delay requirements of multimedia applications     

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.     

Adaptive Cost-Based with Max–Min AMC Routing Algorithm for Increasing Utilization and Reducing Blocking in IEEE 802.16j WiMAX Networks

Based on the IEEE 802.16e standard, WiMAX has proposed a relay-based mechanism, namely IEEE 802.16j, to extend the service area of the Multihop Relay Base Stations (MR-BSs) and to improve the Received Signal Strength quality. IEEE 802.16j thus can achieve two significant advantages: extending the WiMAX service area with a low-cost solution and compatible with the existing WiMAX specifications. The Relay Station (RS) can be classified into three types: Fixed RS, Nomadic RS and Mobile RS according to diverse features of mobility and relaying range. A multihop-relay WiMAX network including various types of RSs exhibits a critical routing issue, i.e., how to determine an efficient relay-based routing path between a Mobile Station (MS) and a MR-BS. This paper thus proposes an IEEE 802.16j-conformed relay-based adaptive competitive on-line routing approach that focuses on the Non-Transparent Relay-Station (NT-RS) mode, where the path with the least cost and the highest AMC coding rate will be selected in terms of the link bandwidth, path length and channel conditions. Numerical results indicate that the proposed routing approach significantly outperforms other approaches in Fractional Reward Loss, network utilization and average end-to-end path delay.     

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     

Adaptive packet scheduling for the uplink traffic in IEEE 802.16e networks

IEEE 802.16e is a telecommunication standard technology designed to support a wide variety of multimedia applications. It defines five service classes, each one with its respective QoS requirements, but does not define the scheduling algorithm for these service classes. In this paper, an adaptive packet scheduling algorithm for the uplink traffic in IEEE 802.16e networks is proposed. This algorithm is designed to be completely dynamic, mainly in networks that use various modulation and coding schemes (MCSs). The algorithm is applied directly to the bandwidth request queues in the base station (BS) and aims at supporting the real‐time and non‐real‐time applications. Using a cross‐layer approach and the states of the bandwidth request queues in the BS, a new deadlines based scheme was defined, aiming at limiting the maximum delay to the real‐time applications. Moreover, this algorithm interacts with the polling management mechanisms of the BS and controls the periodicity of sending unicast polling to the real‐time and non‐real‐time service connections, in accordance with the QoS requirements of the applications. The proposed algorithm was evaluated by means of modeling and simulation in environments where various MCSs were used and also in environments where only one type of modulation was used. The simulations showed satisfactory results in both environments. Copyright © 2012 John Wiley & Sons, Ltd.     

Modeling Contention Based Bandwidth Request Scheme for IEEE 802.16 Networks

IEEE 802.16 standard specifies a contention based bandwidth request scheme for best-effort and non-real time polling services in point-to-multipoint (PMP) architecture. In this letter we propose an analytical model for the scheme and study how the performances of bandwidth efficiency and channel access delay change with the contention window size, the number of contending subscriber stations, the number of slots allocated for bandwidth request and data transmission. Simulations validate its high accuracy.     

Quality-of-service provisioning system for multimedia transmission in IEEE 802.11 wireless LANs

IEEE 802.11, the standard of wireless local area networks (WLANs), allows the coexistence of asynchronous and time-bounded traffic using the distributed coordination function (DCF) and point coordination function (PCF) modes of operations, respectively. In spite of its increasing popularity in real-world applications, the protocol suffers from the lack of any priority and access control policy to cope with various types of multimedia traffic, as well as user mobility. To expand support for applications with quality-of-service (QoS) requirements, the 802.11E task group was formed to enhance the original IEEE 802.11 medium access control (MAC) protocol. However, the problem of choosing the right set of MAC parameters and QoS mechanism to provide predictable QoS in IEEE 802.11 networks remains unsolved. In this paper, we propose a polling with nonpreemptive priority-based access control scheme for the IEEE 802.11 protocol. Under such a scheme, modifying the DCF access method in the contention period supports multiple levels of priorities such that user handoff calls can be supported in wireless LANs. The proposed transmit-permission policy and adaptive bandwidth allocation scheme derive sufficient conditions such that all the time-bounded traffic sources satisfy their time constraints to provide various QoS guarantees in the contention free period, while maintaining efficient bandwidth utilization at the same time. In addition, our proposed scheme is provably optimal for voice traffic in that it gives minimum average waiting time for voice packets. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design indeed provides a good performance in the IEEE 802.11 WLAN's environment, and can be easily incorporated into the hybrid coordination function (HCF) access scheme in the IEEE 802.11e standard.     

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.     

Relay Performance Analysis of TTR and STR Relay Modes in IEEE 802.16j MMR System

The IEEE802.16j standard uses non‐transparent relay stations to extend coverage. There are two types of non‐transparent relay modes, that is, the time‐division transmit and receive (TTR) relay mode which can operate with one of two types of frame structures, a single‐frame and multiframe structure, and the simultaneous transmit and receive (STR) relay mode. In this paper, we analyze the relay performance of TTR and STR relay modes in IEEE 802.16j MMR system. We also propose a fair resource allocation scheme for the downlink relay frame. Numerical results show that relay performance of the TTR with a single‐frame or a multiframe structure and that of the STR relay modes are almost the same in a two‐hop system. However, in a three‐hop system, the TTR mode with a single‐frame structure outperforms other relay modes.     

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     

A new CDMA-based bandwidth request method for IEEE 802.16 OFDMA/TDD systems

This paper proposes an efficient bandwidth request method for a non-real-time polling service and best effort service in the IEEE 802.16 system. The proposed method produces a bandwidth request code to indicate the channel quality and the necessary number of slots. The base station allocates uplink bandwidth depending on the bandwidth request code. Thus, the proposed method can omit the transmission procedure of the bandwidth request message. The performance analysis results show that the proposed method can reduce the delay for the uplink data transmission.     

VoIP Scheduling Algorithm for AMR Speech Codec in IEEE 802.16e/m System

This letter proposes an efficient uplink scheduling algorithm for voice over Internet protocol (VoIP) services with adaptive multi-rate (AMR) speech codec in IEEE 802.16e/m systems. The proposed scheduling algorithm adopts the random access scheme during silent-period to reduce the waste of uplink bandwidth considering the characteristics of AMR speech codec. The numerical results show that the proposed algorithm can increase the maximum supportable number of voice users by 26% compared to the conventional extended real-time polling service (ertPS).     

无线局域网IEEE 802.11的一种高效调度方案

深入分析了无线局域网IEEE 802.11系列标准的现有调度方案,提出了一种基于IEEE 802.11e标准中HCF接入模式的高效调度方案SA-Multipoll.设计了调度帧结构和调度时序,推导了满足时延和带宽要求的准入协商和调度效率公式.通过数值计算和仿真结果证实了SA-Multipoll的调度效率高于singlepoll,也高于现有multipoll方案中效率较高的CP-Multipoll方案.     

RPSF: a new QoS bandwidth request mechanism for the IEEE?802.16

The IEEE 802.16 standard is a Broadband Wireless Access (BWA) technology which offers Quality of Service (QoS) support to different types of applications. This standard defines the physical (PHY) and medium access control (MAC) layers. Its MAC layer defines different types of QoS mechanisms to support various types of applications, being the multicast polling one of these mechanisms. Under this mechanism, based on a contention process, every connection competes to gain access to the channel in order to place its bandwidth requests. In this paper, we propose a new signalling mechanism, called Requests Per Service Flow (RPSF), to reduce the contention phase in the frame. Additionally, we undertake a comparison of this new method with respect to other mechanisms. The simulation results show that our new proposal outperforms other mechanisms recently reported in the literature, in terms of throughput and end-to-end delay.     

基于优先级的IEEE802.16系统接纳控制算法研究

鉴于IEEE802.16标准中未对接纳控制机制提出定义,为了提高系统带宽利用率,在分析现有无线网络接纳控制技术的基础上,结合IEEE802.16的具体机制提出了一种基于业务优先级的接纳控制算法。相比于先到先服务的接纳机制,该算法严格区分业务优先级,为不同优先级业务预留带宽,以保证实时业务的服务质量(QoS)要求。利用NS2网络模拟软件对算法进行了仿真和性能评估。结果表明,本接纳控制算法可以较好地保障高优先级业务的实时性,同时在重负载情况下系统带宽利用率有了明显提高。     

Bandwidth negotiation scheduling with dynamic zone adjustment for 802.16j mobile multihop relay networks

This paper presents a bandwidth negotiation scheduling (BNS) for IEEE 802.16j mobile multihop relay (MMR) networks. In MMR networks, two bandwidth scheduling zones, Access and Relay zones, are specified for direct access and forwarding sessions, respectively. One of the novelties in the proposed BNS is that bandwidth negotiation is conducted between the Access and Relay zones. In other words, a higher‐priority traffic class in a high‐utilization zone may receive extra bandwidth from low‐utilization zone when its delay constraint or bandwidth requirement cannot be satisfied. In addition, when the assigned bandwidth to non‐real‐time polling service (nrtPS) has exceeded its minimum requirement, the proposed BNS can avoid possible starvations for best effort (BE) traffic by receiving extra bandwidth from nrtPS. Through multidimensional Markov formulation, we evaluate the performance of the BNS and compare it with a fixed‐boundary scheme. The analytical results have shown that the proposed BNS can increase delay‐constraint satisfactions for real‐time polling service and decrease the packet loss rate for BE. Furthermore, the overall system throughput can be increased significantly because of an improvement on bandwidth utilization. Copyright © 2012 John Wiley & Sons, Ltd.     

Distributed scheduling based on polling policy with maximal spatial reuse in multi-hop WMNs

The scheduling algorithm based on the three-way handshaking scheme in IEEE 802.16d-2004 standard has some serious problems because of the complexity of the algorithm and low scheduling efficiency.To enhance the scheduling efficiency and improve the performance of multi-hop wireless mesh networks (WMNs), one distributed scheduling algorithm that can maximize the spatial and time reuse with an interference-based network model is proposed.Compared to the graph-based network model, the proposed network model can achieve a better throughput performance with maximal spatial reuse.Furthermore, this proposed scheduling algorithm also keeps fairly scheduling to all links, with a priority-based polling policy.Both the theoretical analysis and simulation results show that this proposed distributed scheduling algorithm is simple and efficient.     

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.