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.     

On the construction of wimax mesh tree

The IEEE 802.16 protocol, also known as WiMAX, has been designed to support long-range communications with high bitrates, using two operation modes: Point-to-Multi-Point (PMP) and Mesh. In the mesh mode, Subscriber Stations (SSs) can directly communicate with each other, thus forming a tree, and can be used to forward other's data packets in a multi-hop fashion. On the contrary, in the PMP mode only one hop communication toward the Base Station (BS) is allowed. In this paper, we investigate the performance of the mesh mode by proposing an algorithm for constructing the WiMAX mesh tree. Our algorithm increases routes' effective throughput by splitting long links into multiple shorter ones. We show through simulations that this approach leads to improving the throughput capacity of WiMAX-based wireless mesh networks.     

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.     

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.

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.     

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.     

A placement mechanism for relay stations in 802.16j WiMAX networks

IEEE 802.16j standard defines Relay Station (RS) to enhance network throughput. Deploying RSs within the serving area of the Base Station (BS) could increase network throughput but raise the hardware cost problem. This paper presents a deployment algorithm for IEEE 802.16j network. According to the history traffic of internet usage, the proposed algorithm deploys as few as possible RSs at suitable locations such that the traffic requirement of each subarea can be satisfied. The proposed relay deployment algorithm mainly consists of three phases. The first phase aims to construct several promising zones where a RS deployed in each zone can improve the transmission rate from mobile station to BS. The second phase further combines several zones into a bigger one aiming at reducing the number of deployed RSs. The last phase selects the relay zones from the promising zones and deploys one RS in each relay zone. Simulation results show that our proposed algorithm can deploy the RSs at the most appropriate locations and hence efficiently reduce transmission delay and save the hardware cost.     

Integration of IEEE 802.11 WLANs with IEEE 802.16-based multihop infrastructure mesh/relay networks: A game-theoretic approach to radio resource management

One of the promising applications of IEEE 802.16 (WiMAX)-based wireless mesh/relay networks is to provide infrastructure/backhaul support for IEEE 802.11-based mobile hotspots. In this article we present an architecture for integrating IEEE 802.11 WLANs with IEEE 802.16-based multihop wireless mesh infrastructure to relay WLAN traffic to the Internet. The major research issues in this integrated architecture are outlined and related work is reviewed. A game-theoretic model is developed for radio resource management in this integrated network architecture. In particular, a multiplayer bargaining game formulation is used for fair bandwidth allocation and optimal admission control of different types of connections (e.g., WLAN connections, relay connections, and connections from standalone subscriber stations) in an IEEE 802.16 base station/mesh router. Both connection-level and inconnection-level performances for this bandwidth management and admission control framework are presented     

Convergence of ethernet PON and IEEE 802.16 broadband access networks and its QoS-aware dynamic bandwidth allocation scheme

IEEE 802.16 and Ethernet Passive Optical Network (EPON) are two promising broadband access technologies for high-capacity wireless access networks and wired access networks, respectively. They each can be deployed to facilitate connection between the end users and the Internet but each of them suffers from some drawbacks if operating separately. To combine the bandwidth advantage of optical networks with the mobility feature of wireless communications, we propose a convergence of EPON and 802.16 networks in this paper. First, this paper starts with presenting the converged network architecture and especially the concept of virtual ONU-BS (VOB). Then, it identifies some unique research issues in this converged network. Second, the paper investigates a dynamic bandwidth allocation (DBA) scheme and its closely associated research issues. This DBA scheme takes into consideration the specific features of the converged network to enable a smooth data transmission across optical and wireless networks, and an end-toend differentiated service to user traffics of diverse QoS (Quality of Service) requirements. This QoS-aware DBA scheme supports bandwidth fairness at the VOB level and class-of-service fairness at the 802.16 subscriber station level. The simulation results show that the proposed DBA scheme operates effectively and efficiently in terms of network throughput, average/maximum delay, resource utilization, service differentiation, etc.     

A survey of cross‐layer protocols for IEEE 802.11 wireless multi‐hop mesh networks

There has been an escalation in deployment and research of wireless mesh networks by both the business community and academia in the last few years. Their attractive characteristics include low deployment cost, a low‐cost option to extend network coverage and ease of maintenance due to their self‐healing properties. Multiple routes exist between the sender and receiver nodes because of the mesh layout that ensures network connectivity even when node or link failures occur. Recent advances among others include routing metrics, optimum routing, security, scheduling, cross‐layer designs and physical layer techniques. However, there are still challenges in wireless mesh networks as discussed in this paper that need to be addressed. Cross‐layer design allows information from adjacent and non‐adjacent layers to be used at a particular layer for performance improvement. This paper presents a survey of cross‐layer protocol design approaches applied to the IEEE 802.11 standards for wireless multi‐hop mesh networks that have been proposed over the last few years for improved performance. We summarize the current research efforts in cross‐layer protocol design using the IEEE 802.11 standard in identifying unsolved issues that are a promising avenue to further research. Copyright © 2016 John Wiley & Sons, Ltd.     

Application of IEEE 802.16 Mesh Networks as the Backhaul of Multihop Cellular Networks

Cellular networks have been widely used to support many new audio-and video-based multimedia applications. The demand for higher data rate and diverse services has driven the research on multihop cellular networks (MCNs). With its ad hoc network features, an MCN can offer many additional advantages, such as increased network throughput, scalability and coverage. However, providing ad hoc capability to MCNs is challenging as it may require proper wireless interfaces. In this article, the architecture of IEEE 802.16 network interface to provide ad hoc capability for MCNs is investigated, with its focus on the IEEE 802.16 mesh networking and scheduling. Several distributed routing algorithms based on network entry mechanism are studied and compared with a centralized routing algorithm. It is observed from the simulation results that 802.16 mesh networks have limitations on providing sufficient bandwidth for the traffic from the cellular base stations when a cellular network size is relatively large.     

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     

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.     

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.     

GI/Geom/1 queue based on communication model for mesh networks

In mesh networks architecture, it should be permitted to visit the mobile client points. Whereas in mesh networks environment, the main throughput flows usually communicate with the conventional wired network. The so‐called gateway nodes can link directly to traditional Ethernet, depending on these mesh nodes, and can obtain access to data sources that are related to the Ethernet. In wireless mesh networks (WMNs), the quantities of gateways are limited. The packet‐processing ability of settled wireless nodes is limited. Consequently, throughput loads of mesh nodes highly affect the network performance. In this paper, we propose a queuing system that relied on traffic model for WMNs. On the basis of the intelligent adaptivenes, the model considers the influences of interference. Using this intelligent model, service stations with boundless capacity are defined as between gateway and common nodes based on the largest hop count from the gateways, whereas the other nodes are modeled as service stations with certain capacity. Afterwards, we analyze the network throughput, mean packet loss ratio, and packet delay on each hop node with the adaptive model proposed. Simulations show that the intelligent and adaptive model presented is precise in modeling the features of traffic loads in WMNs. Copyright © 2013 John Wiley & Sons, Ltd.     

基于IEEE802．16的无线Mesh网络的冲突改进方法

文章首先介绍了IEEE 802．16的mesh结构以及Mesh模式下协同分布式调度，对mesh结构下的三次握手机制进行了阐述，提出了原协议中三次握手机制的冲突问题，并在此基础上进行分析，针对所存在的冲突，提出了一种三次握手机制改进方法。通过分析和NS-2仿真表明，该方法性能较好，不但缩短了端到端时延，而且同时增加了吞吐量。     

FEBA: A Bandwidth Allocation Algorithm for Service Differentiation in IEEE 802.16 Mesh Networks

In wireless mesh networks, the end-to-end throughput of traffic flows depends on the path length, i.e., the higher the number of hops, the lower becomes the throughput. In this paper, a fair end-to-end bandwidth allocation (FEBA) algorithm is introduced to solve this problem. FEBA is implemented at the medium access control (MAC) layer of single-radio, multiple channels IEEE 802.16 mesh nodes, operated in a distributed coordinated scheduling mode. FEBA negotiates bandwidth among neighbors to assign a fair share proportional to a specified weight to each end-to-end traffic flow. This way traffic flows are served in a differentiated manner, with higher priority traffic flows being allocated more bandwidth on the average than the lower priority traffic flows. In fact, a node requests/grants bandwidth from/to its neighbors in a round-robin fashion where the amount of service depends on both the load on its different links and the priority of currently active traffic flows. If multiple channels are available, they are all shared evenly in order to increase the network capacity due to frequency reuse. The performance of FEBA is evaluated by extensive simulations. It is shown that wireless resources are shared fairly among best-effort traffic flows, while multimedia streams are provided with a differentiated service that enables quality of service.     

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。     

一种基于IEEE802.16无线MESH网络集中调度机制的时隙分配方法

在基于IEEE 802.16的无线Mesht网络中,时隙分配算法对网络性能有重要影响.针对现有时隙分配算法只研究上行链路且时隙分配的结果导致中继节点在转发数据时频繁在相邻时隙间进行收发切换的问题,提出了一种上下行链路通用的时隙分配方法,对于上行链路,跳数较小节点的数据优先传输,而对于下行链路,跳数较大节点的数据优先传输,在传输路径上采用逐跳传输的策略.仿真结果证明了该算法的有效性.     

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.