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     

On the impact of physical layer awareness on scheduling and resource allocation in broadband multicellular IEEE 802.16 systems [Radio Resource Management and Protocol Engineering for IEEE 802.16]

Multicellular networks based on the IEEE 802.16 standard appear to be very promising candidates to provide end users with broadband wireless access. However, they also pose interesting challenges in terms of radio resource management, where several design choices are not specified in the standard, intentionally left open to implementors. For this reason, we focus in this article on scheduling and resource allocation, and investigate how they could operate in a cross-layer fashion. In particular, we describe the principles of joint scheduling and resource allocation for IEEE 802.16 operating in AMC mode, and discuss the critical role played by physical layer considerations, especially intercell interference estimation and channel state awareness, in the obtained performance. This leads to identifying key open issues and possible general solutions     

Adaptive power allocation and call admission control in multiservice WiMAX access networks [Radio Resource Management and Protocol Engineering for IEEE 802.16]

To achieve a successful broadband wireless access solution, the IEEE 802.16 subcommittee has released a series of standards for WiMAX (worldwide interoperability for microwave access). From a technical viewpoint, WiMAX is a feasible alternative to the wired Internet access solutions such as cable modem and DSL. Nevertheless, from the commercial viewpoint, whether the promise of WiMAX will be materialized still depends on its revenue rate to telecom operators and its service quality to the subscribers. In such a context, this article addresses two resource management mechanisms in WiMAX access networks, that is, adaptive power allocation (APA) and call admission control (CAC), from the perspectives of both service providers and WiMAX subscribers. APA emphasizes how to share the limited power resource of base station among different WiMAX subscribers and further influences the access bandwidth of each subscriber; CAC highlights how to assign a subscriber's access bandwidth to different types of applications. Moreover, to build a WiMAX access network, APA and CAC have to work cooperatively to provide cross-layer resource management. In this article we focus on the OFDMA-TDD system, which allows high spectrum-utility efficiency on uplink and downlink channels in the asymmetric scenario of "lastmile" Internet access. We conclude the article with an optimization strategy to balance service provider's revenue and subscriber's satisfaction     

Radio resource management games in wireless networks: an approach to bandwidth allocation and admission control for polling service in IEEE 802.16 [Radio Resource Management and Protocol Engineering for IEEE 802.16]

Game theory is a mathematical tool developed to understand competitive situations in which rational decision makers interact to achieve their objectives. Game theory techniques have recently been applied to various engineering design problems in which the action of one component impacts (and perhaps conflicts with) that of any other component. In particular, game theory techniques have been successfully used for protocol design and optimization (e.g., radio resource management, power control) in wireless networks. In this article we present an overview of different game theory formulations. Then a survey on the game-theory-based resource management and admission control schemes in different wireless networks is presented, and several open research issues are outlined. To this end, we propose an adaptive bandwidth allocation and admission control scheme for polling service in an IEEE 802.16-based wireless metropolitan area network. A noncooperative game is formulated, and the solution of this game is determined by the Nash equilibrium for the amount of bandwidth offered to a new connection. The admission control policy ensures QoS for all connections in the system     

Radio resource management and protocol engineering for IEEE 802.16 [Guest Editorial]

The special section features six articles that focus on radio resource management issues in IEEE 802.16/WiMAX-based broadband wireless systems. This guest editorial discusses the major issues pertaining to the topic and summarizes the articles included in this section.     

Resource management for symmetrical applications over heterogeneous services in IEEE 802.16

Wireless Networks - Symmetrical applications are multimedia applications that require both uplink and downlink connectivity. The demands of symmetrical applications are expected to grow rapidly in...     

S-WiMAX: adaptation of IEEE 802.16e for mobile satellite services - [WiMAX update]

Mobile satellite services are attracting renewed attention stemming from the FCC ancillary terrestrial component ruling that allows satellite spectrum to be used for integrated terrestrial services in the footprint of the satellite. This attention is focused on the development of dual-mode satellite-terrestrial devices to facilitate hybrid satellite-terrestrial networks intended by the ATC order. The satellite component in these dual-mode devices is best adapted from the air interface chosen for the ATC to optimize form factor, especially for small hand-held devices, mobility management, power efficiency, and a common core network functionality. With the advent of WiMAX as a viable 4G technology, satellite adaptation of WiMAX has been considered for the satellite services coupled with WiMAX ATC. The main considerations for satellite adaptation of WiMAX, relative to its terrestrial counterpart, are reduced link margin and longer transmission delays ? both absolute delay from the center of a spot beam to the satellite and differential delay between the beam edge and the beam center to the satellite. These considerations suggest adaptation of the subchannelization schemes, the frame synchronization methods, and the ranging process in WiMAX to make it operable over satellite, while keeping the general framework of the WiMAX protocol stack intact, thereby facilitating the incorporation of S-WiMAX into a common baseband processor with terrestrial WiMAX; this allows S-WiMAX to be added to terrestrial WiMAX devices with minimal cost and formfactor impact. Methods for these adaptations are considered here.     

Radio resource management for cellular CDMA systems supporting heterogeneous services

A novel radio resource management (RRM) scheme for the support of packet-switched transmission in cellular CDMA systems is proposed by jointly considering the physical, link, and network layer characteristics. The proposed resource management scheme is comprised of a combination of power distribution, rate allocation, service scheduling, and connection admission control. Power distribution allows individual connections to achieve their required signal-to-interference-plus-noise ratio, while rate allocation guarantees the required delay/jitter for real-time traffic and the minimum transmission rate requirement for non-real-time traffic. Efficient rate allocation is achieved by making use of the randomness and burstiness; of the packet generation process. At the link layer, a packet scheduling scheme is developed based on information derived from power distribution and rate allocation to achieve quality of service (QoS) guarantee. Packet scheduling efficiently utilizes the system resources in every time slot and improves the packet throughput for non-real-time traffic. At the network layer, a connection admission control (CAC) scheme based on the lower layer resource allocation information is proposed. The CAC scheme makes use of user mobility information to reduce handoff connection dropping probability (HCDP). Theoretical analysis of the grade of service performance, in terms of new connection blocking probability, HCDP, and resource utilization, is given. Numerical results show that the proposed RRM scheme can achieve both effective QoS guarantee and efficient resource utilization.     

QoS-oriented resource allocation for streaming flows in?IEEE802.16e Mobile WiMAX

Users in OFDMA-based WiMAX are subject to Adaptive Modulation and Coding (AMC) which implies more robust and hence less frequency efficient modulation and coding for users experiencing bad radio conditions. When users are mobile, this implies lower throughput as they move away from the base station for instance. This may be acceptable for data users, but not for streaming ones which require a constant bit rate throughout the cell. We propose, in this work, a new QoS-oriented resource allocation strategy wherein streaming flows experiencing bad radio conditions are allocated more sub-carriers so as to keep their bit rate constant as they move around in the cell. The risk is however an increase in the dropping rate. To minimize the latter without increasing blocking too much, they are second subject to a state-dependent admission control scheme where the degree of acceptance depends on the density of the users in a given location. We develop an analytical model which allows us to derive some performance measures such as blocking and dropping probabilities. Our results quantify how these metrics vary with the load as well as the admission strategies.     

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.     

Scheduling in IEEE 802.16e mobile WiMAX networks: key issues and a survey

Interest in broadband wireless access (BWA) has been growing due to increased user mobility and the need for data access at all times. IEEE 802.16e based WiMAX networks promise the best available quality of experience for mobile data service users. Unlike wireless LANs, WiMAX networks incorporate several quality of service (QoS) mechanisms at the Media Access Control (MAC) level for guaranteed services for data, voice and video. The problem of assuring QoS is basically that of how to allocate available resources among users in order to meet the QoS criteria such as delay, delay jitter and throughput requirements. IEEE standard does not include a standard scheduling mechanism and leaves it for implementer differentiation. Scheduling is, therefore, of special interest to all WiMAX equipment makers and service providers. This paper discusses the key issues and design factors to be considered for scheduler designers. In addition, we present an extensive survey of recent scheduling research. We classify the proposed mechanisms based on the use of channel conditions. The goals of scheduling are to achieve the optimal usage of resources, to assure the QoS guarantees, to maximize goodput and to minimize power consumption while ensuring feasible algorithm complexity and system scalability.     

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.     

Radio resource management schemes for combined GSM/GPRS mobile systems

Data services like Web browsing, e‐mail and file transfer are becoming more and more popular in cellular systems. In contemporary systems like Global System for Mobile communications (GSM), data transfer has been circuit‐switched, that is, physical resources are allocated to a user for the entire call/session duration. However, this is inefficient in case of bursty traffic, where bursts are separated by long intervals of inactivity. This has been the main reason for the introduction of General Packet Radio Service (GPRS), which on the one hand acts as a mobile access network to the Internet, while on the other hand it enables the operator to offer a wide variety of value‐added services [Wireless Access Protocol (WAP) over GPRS, e/m‐banking, e/m‐commerce, push services, etc.] efficiently. However, in contemporary commercial implementations of GPRS the radio resource allocation algorithm does not take into account the Quality of Service (QoS)‐related service characteristics—although such information is exchanged between the terminal and the network—and consequently all service requests are treated the same way (‘best effort’). In this paper, we propose and evaluate via a simulation platform various Radio Resource Management (RRM) schemes capable of differentiating the handling of ‘service requests’ (in uplink and downlink), taking into account the GPRS‐related QoS parameters (precedence, reliability, delay, mean and peak throughput). The evaluation is performed for a range of voice (circuit‐switched) traffic loads, number of Transmit Receive eXchange (TRXs), offered data (packet‐switched) services characteristics, number of dedicated Packet Data Channels (PDCHs), and so on, taking into account the respective QoS requirements for both service types (circuit‐ and packet‐switched). Copyright © 2003 John Wiley & Sons, Ltd.     

Mobility management schemes for real‐time traffic and resource allocation in IEEE 802.16e mobile network

In this paper, our aim is to develop in IEEE802.16e Wireless Networks with link adaptation, in the presence of real‐time traffic call admission control (CAC) schemes. These CAC propose various scenarios of resource splitting and handling the intracell mobility. In particular, we consider two types of intracell mobility classes : low mobility class for mobiles moving usually with low speed between the neighboring regions of the cell and high mobility class for those moving with high speed and that can skip more than one region before changing their modulation. For this reason, we assume a time threshold T _th that determines the minimum time a call must remain in a region before the base station changes its modulation. And we compare it with the time that a call may spend in a region to decide whether the base station will change its modulation or not. In the beginning, we introduce two CAC schemes. In the first one, we reserve a portion of resources to mobiles in migration with both high and low mobility. And in the second one, we give the priority just to mobiles in migration with high mobility. Then, we calculate the impact in the blocking and dropping probabilities. We show by numerical results that by the proposed CAC schemes, we can find a resource management that outperforms well under different types of mobility. But, to find a good tradeoff between dropping the calls in migration and blocking the new calls, we introduce the optimization problem in the second part. So, we are faced to the necessity of optimizing the results found in the first part. Therefore, we define an objective function to optimize, in order to ensure the highest quality of service for users and to give a better stability state between the dropping and blocking probability. We show that the proposed objective function gives the optimal resources allocation between the migrating and new arriving calls in the cell. Copyright © 2015 John Wiley & Sons, Ltd.     

WiMAX系统架构以及无线资源管理机制

研究了基于IEEE 802.16标准的WiMAX系统架构,给出了端到端的网络参考模型,并就当前WiMAX网络标准现状进行了介绍,特别是详细阐述了WiMAX系统的无线资源管理机制的体系结构,对其中的关键算法进行了详细研究.     

IEEE 802.16密钥管理协议的安全问题分析与改进方案

IEEE 802.16在MAC层设计的安全子层没有完全解决宽带无线接入的安全问题.本文分析了认证和密钥管理(PKM)协议的安全缺陷,针对其可能遭受的攻击,提出了改进方案,并提出一种基于PKM的支持快速切换的密钥信息安全漫游机制.     

IEEE Radio Communications components systems, and networks [Guest Editorial]

The purpose of the special issue is to illustrate the complexity of radio communications standards by emphasizing the variety of technical topics that are being considered for beyond 3G (B3G) systems. All of the contributions are from the Virtual Centre of Excellence in Mobile and Personal Communications (Mobile VCE).     

Radio resource management for cooperative wireless communication systems with organized beam-hopping techniques [accepted from open call]

Readiness in deployment and flexibility in radio resource configuration are the main features of future wireless communication systems. A cooperative wireless communication system (CWCS) is proposed to follow the same principle, aiming at improving the overall performance of a wireless system with the support of advanced beam-hopping techniques. In this article, we propose a multiloop radio resource management mechanism for the CWCS based on the organized beam-hopping (OBH) technique. The proposed RRM mechanism enhances the robustness of the CWCS, based on the OBH technique working with fast temporal-spatial variant traffic. The results show that the system performance can be further improved by hybrid transmission and event- driven access management techniques.     

Radio resource allocation for interference management in mobile broadband OFDMA based networks

This paper focuses on the inter‐cell interference (ICI) management problem in the downlink channel for mobile broadband wireless OFDMA‐based systems. This subject is addressed from the standpoint of different interrelated resource allocation mechanisms operating in multi‐cell scenarios in order to exploit frequency and multi‐user diversity: ICI coordination/avoidance and adaptive subcarrier and power allocation. Even though these methods can be applied in a stand‐alone way, a significant performance improvement is achieved if they are jointly designed and operate in a combined basis. Several alternatives for mixed frequency and power ICI coordination schemes are proposed in this paper. Connected with a proper power mask‐based design, the potential gain of a flexible frequency sectorization solution, halfway between fractional/soft frequency reuse and pure frequency sectorization, is explored. The main objective is to outperform fractional/soft frequency reuse offering an attractive trade‐off between cell‐edge user data rates and average cell throughput. Proposals concerning ICI coordination/avoidance have been evaluated in combination with several heuristic adaptive subcarrier and power allocation algorithms. Copyright © 2009 John Wiley & Sons, Ltd.