Broadband Wireless Access Technology Research Articles

Congestion-Based Pricing Resource Management in Broadband Wireless Networks

Supporting the diverse QoS requirements of multimedia applications is an essential requirement for broadband wireless access (BWA) networks. Due to the projected dynamics in traffic patterns, more capable resource management functionalities are needed. We propose a game-theoretic, congestion-based pricing scheduler that incorporates two sub-schemes: a bandwidth provisioning sub-scheme to address the bandwidth scarcity to provision in fourth generation (4G) BWA technologies and an efficient packet scheduler sub-scheme. To the best of our knowledge, the proposed scheduler is the first one to simultaneously control congestion and fairness while providing differentiated QoS guarantees in BWA networks. Simulation results show that the proposed scheme realizes our objectives of controlling congestion, providing differentiated QoS guarantees, and catering to proportional fairness among the different network classes and among connections within the same class.

Technology and market conditions toward a new competitive landscape in the wireless access market

This article argues that the wireless telecommunication market is about to witness a shift in business models and market structure as a result of the deployment of new broadband access technologies, spectrum management techniques, policy-based network management, and the drive of new entrants to compete against the incumbents. The article discusses four agents of evolutionary changes: a range of broadband wireless access standards and technologies that are front-runners in the industry's efforts to embody the next generation of wireless networks; new provider-customer relationships facilitated through changes in the usual contract patterns that will allow consumers to enter short-term and spot contracts with the new wireless providers; an overview of the current debate on spectrum management; and an explanation of how autonomic communications and policy-based management would support the new structure. Finally, the article asserts the necessity for the integration of the heterogeneous technologies that make up this emerging, hybrid wireless landscape, and describes the economic characteristics of a new competitive scenario.

Wireless telemedicine services over integrated IEEE 802.11/WLAN and IEEE 802.16/WiMAX networks

Wireless telemedicine, also referred to as mobile health, which capitalizes on advances of wireless technologies to deliver health care and exchange medical knowledge anywhere and any time, overcomes most of geographical, temporal, and even organizational barriers to facilitate remote diagnosis and monitoring, and transfer of medical data and records. In this article we investigate the application of integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN broadband wireless access technologies along with the related protocol issues for telemedicine services. We first review IEEE 802.11/WLAN and IEEE 802.16/WiMAX technologies, and make a comparison between IEEE 802.11/WLAN and IEEE 802.16/WiMAX. Then some open research issues in the integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN networks are discussed, especially regarding QoS support, radio resource management, scheduling and connection admission control schemes, as well as handover and mobility management. Finally, applications and deployment scenarios of integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN for telemedicine services are further deliberated.

Resource management to increase connection capacity of real-time streaming in mobile WiMAX

With large network coverage, high transmission rate, strong quality of service (QoS) assurance and inexpensive deployment cost, mobile WiMAX has emerged as one of the most promising broadband wireless access technologies. However, resource management is still a challenging issue between system capacity and user gratification, especially for multimedia transmission which ordinarily requires strict delay constraints. In this study, the authors propose an adaptive call admission control in order to efficiently increase system capacity. The control mechanism can admit an incoming video on demand (VOD) connection establishing even without sufficient idle slots/bandwidth to meet the QoS requirement. With consideration of the existing VOD user stream buffer (USB), our scheduling mechanism performs adaptive admission control and QoS provision feasible each time. Also employing adaptive modulation and coding (AMC) scheme, each connection keep its fluency of real-time video performance over dynamic wireless channel status. The authors evaluate the concurrent stream connection number and connection blocking probability with different resource management strategies.

Efficient Uplink Bandwidth Request with Delay Regulation for Real-Time Service in Mobile WiMAX Networks

The emerging broadband wireless access technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous wireless access to the broadband service at low cost. This paper proposes an efficient uplink bandwidth request-allocation algorithm for real-time services in Mobile WiMAX networks based on IEEE 802.16e. In order to minimize bandwidth wastage without degrading quality of service (QoS), we introduce a notion of target delay and propose dual feedback architecture. The proposed algorithm calculates the amount of bandwidth request such that the delay is regulated around the desired level to minimize delay violation and delay jitter for real-time services. Also, it can increase utilization of wireless channel by making use of dual feedback, where the bandwidth request is adjusted based on the information about the backlogged amount of traffic in the queue and the rate mismatch between packet arrival and service rates. Due to the target delay and dual feedback, the proposed scheme can control delay and allocate bandwidth efficiently while satisfying QoS requirement. The stability of the proposed algorithm is analyzed from a control-theoretic viewpoint, and a simple design guideline is derived based on this analysis. By implementing the algorithm in OPNET simulator, its performance is evaluated in terms of queue regulation, optimal bandwidth allocation, delay controllability, and robustness to traffic characteristics.

A CMOS Analog Front-end Receiver with Desensitization to Input Capacitance for Broadband Optical Wireless Communication

Line-of-sight optical wireless channels are emerging as a promising broadband wireless access technology. This paper describes a front-end transimpedance amplifier (TIA) that is designed to overcome challenges faced by high-speed optical wireless links requiring receivers with wide field-of-view (FOV) and high dynamic range for signal acquisition/tracking. This transimpedance amplifier employs a capacitive feedback configuration, with a selfbiased automatic gain control (AGC) circuit to increase the input dynamic range. The transimpedance amplifier is designed for integration with wide FOV detectors with associated capacitance up to 5pF and its performance is insensitive (within 5%) to an order of magnitude variation in input capacitance. The self-biased AGC allows 42dB dynamic range in received optical power to accommodate varying link ranges and different optical wireless (OW) system configurations. A test chip was implemented in a lowcost 0.5- ¹ m CMOS process and achieves a maximum TIA gain of 52dB­ , -3dB bandwidth of 523MHz at 5pF input capacitance, and variable TIA gain from 52dB­ to 36dB­ without instability. Noise measurements show input-referred noise current spectral density of 22pA/ p Hz for 5pF input capacitance. Optical measurements show good eye diagrams at 750Mb/s. The power dissipation is 53mW from dual 3.3V and 1.8V supply voltages.

An overview of next-generation mobile WiMAX technology

The growing demand for mobile Internet and wireless multimedia applications has motivated the development of broadband wireless access technologies in recent years. Mobile WiMAX has enabled convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. Since January 2007, the IEEE 802.16 working group has been developing a new amendment of the IEEE 802.16 standard (i.e., IEEE 802.16m) as an advanced air interface to meet the requirements of ITU-R/IMT-advanced for 4G systems, as well as for the next-generation mobile network operators. Depending on the available bandwidth and multi-antenna mode, the next-generation mobile WiMAX will be capable of over-the-air data-transfer rates in excess of 1 Gb/s and of supporting a wide range of high-quality and high-capacity IP-based services and applications while maintaining full backward compatibility with the existing mobile WiMAX systems to preserve investments and continuing to support first-generation products. This tutorial describes the prominent technical features of IEEE 802.16m and the potential for successful deployment of the next generation of mobile WiMAX in 2011+.

Using WiMAX to Improve Volcano Monitoring during an Emergency: A Feasibility Study of the WEIRD System Applied to the Campi Flegrei Volcanic Area Scenario (Southern Italy)

IEEE Standard for Local and Metropolitan Area Networks (hereafter IEEE 802.16; online at http://standards.ieee.org/getieee802/802.16.html) is one of the most promising mobile and fixed broadband wireless access technologies for next-generation all-IP networks in the 3.5 GHz band (European spectrum profile). Commonly known as Universal WiMAX (worldwide inter-operability for microwave access), this access technology reaches a high bit rate and covers large areas with a single base station, making it possible to offer connectivity to end users in a cost-effective way. A further useful property of the WiMAX technology is that the transmission can be used both in line-of-sight (LOS) and non-line-of-sight (NLOS) environments, allowing highly feasible communications (WiMAX Forum 2004). Thanks to these features, IEEE 802.16 opens the way to the use of wireless technologies in the environmental monitoring of areas such as seismic and volcanic zones. Volcanic eruptions, in particular, are among the highest natural risks in the world. About 600 volcanoes have erupted in historical times, and many are located near densely populated areas. An adequate monitoring system is essential to understanding the physical processes preceding an eruption and for mitigating the risk of such an event. Active volcano surveillance is primarily based on the analysis of geophysical and geochemical parameters gathered by monitoring networks. Seismological methods are among the most useful methods for monitoring volcanoes. In fact, several types of seismic signals, e.g. , volcano-tectonic earthquakes (VT), long-period events (LP), and volcanic tremors, can occur before and during an eruption (McNutt 2005). The analysis and interpretation of these seismic signals is a very important task for volcanic eruption forecasting. WiMAX technology can be applied to provide broadband wireless access in volcano monitoring scenarios to solve some of the problems that prevent us from improving surveillance of volcanic activities during emergencies. In particular, this paper focuses on a novel …

A bandwidth request reiteration mechanism for IEEE 802.16 wireless networks

The IEEE 802.16 is a leading technology for Broadband Wireless Access (BWA), where a Base Station (BS) provides a set of Subscriber Stations (SSs) with first-mile network access. Each SS has multiple connections directed to the BS, which are assigned bandwidth on a demand basis. Specifically, the BS allocates part of the channel as request slots, which are accessed by best-effort connections in a random access manner to transmit bandwidth requests. Although bandwidth requests sent by different SSs may collide the standard does not specify an explicit acknowledgment mechanism. This, and the bandwidth being assigned by the BS to each SS as a whole, may lead to critical inconsistencies between the perception of the SSs' requirements at the BS and the actual SSs' requirements, which in turn may entail SS service disruption. While the standard suggests that an SS should regularly update the BS about the backlog of its connections, the algorithm to do so is left unspecified. In this paper we propose a simple, yet effective, mechanism to be employed by the SSs, called Bandwidth Request Reiteration (BR2), which prevents deadlock from occurring. Using detailed packet-level simulation, we compare BR2 to an alternative approach based on timeout, and show that BR2 achieves better performance, in terms of the average transfer delay, while it does not incur a significant additional overhead, in terms of MAC signaling.

An analytical evaluation of mobility management in integrated WLAN-UMTS networks

Ensuring uninterrupted service continuity for handoff calls in an all-IP inter-networked heterogeneous environment requires successful session management among participating access networks. As such, a mobility-aware novel interworking architecture is presented in this article that facilitates session management including session establishment and seamless session handoff across different networks. This framework conveniently enables any 3G cellular technology such as the Universal Mobile Telecommunications System (UMTS) to interwork with a given Broadband Wireless Access (BWA) technology such as the Worldwide Interoperability for Microwave Access (WiMAX) network or the Wireless Local Area Network (WLAN) under a common signaling platform. This framework exploits the IP Multimedia Subsystem (IMS) as a universal coupling mediator for real-time session negotiation and management. Next, a Queuing Theory based analytical model for evaluating the performance of vertical handoff management between these interworked 3rd Generation (3G) cellular networks and the WLANs is presented. The analysis includes vertical handoff performance measures such as delay, transient packet loss, jitter, and signaling overhead/cost. The latter part of this paper presents some results from OPNET based simulations for the verification of the analytical model and results.

Dynamic hybrid automatic repeat request (DHARQ) for WiMAX – Mobile multihop relay using adaptive power control

Wireless multihop network is currently attracting much attention as a new wireless broadband access technology due to numerous benefits. This work proposes a power control scheme for WiMAX multihop relay system. In contrast to existing power control and optimization approaches, our proposed method uses an adaptive Channel Quality Measurement for a relay station to reduce interferences to other mobile station (MS) or relay station (RS) within the same cell and hence increase the number of hops per link and consequently maximize the spatial reuse. The proposed power control is applied to a new dynamic HARQ algorithm for adaptive channel quality enhancement. Simulation results have indicated that the proposed approach achieves superior BER/PER performance enhancement in comparison to previous related works.

Broadband wireless real time communication

Today's Internet access technologies are not able to provide broadband connectivity to all areas in a cost-effective way for telecom operators. Wired technologies still require a noteworthy investment in cabling infrastructures, whereas wireless access technologies cannot deliver high-speed connections to several users simultaneously. To address this issue, a very interesting solution has been defined by the IEEE 802.16 working group, in particular the IEEE 802.16-2004 and IEEE 802.16e-2005 standards. IEEE 802.16-2004 is a fixed broadband wireless access technology, capable to provide high data rate connections over large areas.

Plug into the Online Database and Play Mobile Web 2.0

The next generation of open mobile device platforms will use wireless broadband access technology and human-computer interface advances to allow remote plug and play with Web 2.0 applications. A case study of mobile commerce reveals a complete workflow, from user log in to entry creation to barcode scanning.

Dynamic Bandwidth Allocation for QoS in IEEE 802.16 Broadband Wireless Networks

IEEE 802.16 broadband wireless access (BWA) technology is suitable for providing multimedia applications without accessing the wired networks directly. Although IEEE 802.16 standard well defines the quality of service (QoS) framework, it makes no specific recommendation with regard to the bandwidth allocation. In this paper, we propose an algorithm for allocating bandwidth in response to dynamic changes in the arrival rate such that the total bandwidth is efficiently utilized.

Bandwidth Management of WiMAX Systems and Performance Modeling

WiMAX has been introduced as a competitive alternative for metropolitan broadband wireless access technologies. It is connection oriented and it can provide very high data rates, large service coverage, and flexible quality of services (QoS). Due to the large number of connections and flexible QoS supported by WiMAX, the uplink access in WiMAX networks is very challenging since the medium access control (MAC) protocol must efficiently manage the bandwidth and related channel allocations. In this paper, we propose and investigate a cost-effective WiMAX bandwidth management scheme, named the WiMAX partial sharing scheme (WPSS), in order to provide good QoS while achieving better bandwidth utilization and network throughput. The proposed bandwidth management scheme is compared with a simple but inefficient scheme, named the WiMAX complete sharing scheme (WCPS). A maximum entropy (ME) based analytical model (MEAM) is proposed for the performance evaluation of the two bandwidth management schemes. The reason for using MEAM for the performance evaluation is that MEAM can efficiently model a large-scale system in which the number of stations or connections is generally very high, while the traditional simulation and analytical (e.g., Markov models) approaches cannot perform well due to the high computation complexity. We model the bandwidth management scheme as a queuing network model (QNM) that consists of interacting multiclass queues for different service classes. Closed form expressions for the state and blocking probability distributions are derived for those schemes. Simulation results verify the MEAM numerical results and show that WPSS can significantly improve the network's performance compared to WCPS.

Optimal placement and channel assignment of relay stations in heterogeneous wireless mesh networks by modified Bender’s decomposition

Fixed Broadband Wireless Access (FBWA) technology is designed to serve as a wireless DSL replacement to provide broadband Internet access in underserved areas where no other access technology exists. Due to the enormousness of the target service area, relay equipment play an important role in such networks, and the installation and maintenance cost of the network is directly proportional to the cost of the relay equipment. To minimize the network operational cost, an optimization framework which computes the minimum number of relay stations and their corresponding placements and channel assignments in the network is desired. Because the problem is NP-hard, we propose an efficient optimization algorithm based on a modified version of Bender’s decomposition to iteratively compute converging bounds to the problem solution. Our numerical results show that by using a few relay stations in a rural community, broadband Internet access can be established in a cost effective manner.

Joint Power-Frequency-Time Resource Allocation in Clustered Wireless Mesh Networks

Wireless mesh networking is an emerging technology for future broadband wireless access. Future wireless networking can benefit from a robust and reliable wireless mesh backbone rendered by mesh routers, providing an all-wireless ambience. Due to the requisite multichannel communications for high-speed data transmissions, power allocation for opportunistically exploiting fading wireless channels, and packet scheduling for QoS provisioning, joint power-frequency-time resource allocation is indispensable. In this article we propose a low-complexity intracluster resource allocation algorithm, taking power allocation, subcarrier allocation, and packet scheduling into consideration. Numerical results demonstrate that our scheme is near optimal, and that our optimality-driven resource allocation approach outperforms a greedy algorithm, working out a better performance compromise among throughput, packet dropping rate, and packet delay.

Multicarrier transmission

Multicarrier transmission has recently become popular, particularly in the area of wireless broadband access technology. This tutorial overview paper formulates multicarrier transmission from a signal processing point of view and provides an in-depth analytical understanding of its constituent fundamental concepts. Multicarrier transmission and reception principles are first derived for the single transmitting antenna and single receiving antenna systems and then extended to support more general and modern communication systems that use multiple transmitting and multiple receiving antennas.

Comparing WiMAX and HSPA — a guide to the technology

Intel has referred to WiMAX as `the most important thing since the Internet itself'. So is this true and if so what is so special about WiMAX? This paper provides a basic overview of WiMAX in terms of what it is and how it works, its throughput, coverage and security features as well as the services it could support. The paper also looks at high-speed packet access, another broadband wireless access technology, and compares it with WiMAX.

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