Showing papers on "IEEE 802.11e-2005 published in 2008"
11 May 2008
TL;DR: An overview of the latest draft proposed for IEEE 802.11p, named wireless access in vehicular environment, also known as WAVE, is provided to provide an insight into the reasoning and approaches behind the document.
Abstract: Vehicular environments impose a set of new requirements on today's wireless communication systems. Vehicular safety communications applications cannot tolerate long connection establishment delays before being enabled to communicate with other vehicles encountered on the road. Similarly, non-safety applications also demand efficient connection setup with roadside stations providing services (e.g. digital map update) because of the limited time it takes for a car to drive through the coverage area. Additionally, the rapidly moving vehicles and complex roadway environment present challenges at the PHY level. The IEEE 802.11 standard body is currently working on a new amendment, IEEE 802.1 lp, to address these concerns. This document is named wireless access in vehicular environment, also known as WAVE. As of writing, the draft document for IEEE 802.11p is making progress and moving closer towards acceptance by the general IEEE 802.11 working group. It is projected to pass letter ballot in the first half of 2008. This paper provides an overview of the latest draft proposed for IEEE 802.11p. It is intended to provide an insight into the reasoning and approaches behind the document.
1,240 citations
01 Jan 2008
TL;DR: This special issue, which focuses on event analysis in broad problem domains, has witnessed the effectiveness of using both static and temporal information in event recognition from other video sources.
Abstract: Event analysis in videos is a critical task in many applications. Activity recognition that aims to recognize actions from video and in particular abnormal event recognition in surveillance video has received significant attention from the research community. In this special issue, we focus on event analysis in broad problem domains. Event recognition in specific domains, such as highlight detection in sports videos, has attracted much interest in the past decade. Recently, due to the emergence of online video search, the research community has become interested in event content analysis for both broadcast and user-generated videos. For news videos, Large-Scale Concept Ontology for Multimedia (LSCOM) has defined 56 event/activity concepts, covering a broad range of events such as airplane flying, car crash, riot, people marching, and so on. Researchers have also started to investigate event recognition from other video sources, such as education videos and medical videos. For these applications, we have witnessed the effectiveness of using both static and temporal information.
428 citations
TL;DR: This article investigates the key MAC enhancements that help 802.11n achieve high throughput and high efficiency, and concludes that overall, the two-level aggregation is the most efficacious.
Abstract: IEEE 802.11n is an ongoing next-generation wireless LAN standard that supports a very highspeed connection with more than 100 Mb/s data throughput measured at the medium access control layer. This article investigates the key MAC enhancements that help 802.11n achieve high throughput and high efficiency. A detailed description is given for various frame aggregation mechanisms proposed in the latest 802.11n draft standard. Our simulation results confirm that A-MSDU, A-MPDU, and a combination of these methods improve extensively the channel efficiency and data throughput. We analyze the performance of each frame aggregation scheme in distinct scenarios, and we conclude that overall, the two-level aggregation is the most efficacious.
380 citations
TL;DR: An overview of relay-based wireless systems, focusing on the different modes of operation, framing structures, and network entry procedures, is provided, which highlights when different features within the standard are most appropriate.
Abstract: Multihop wireless systems have the potential to offer improved coverage and capacity over single-hop radio access systems. Standards development organizations are considering how to incorporate such techniques into new standards. One such initiative is the IEEE 802.16j standardization activity, adding relay capabilities to IEEE 802.16 systems. This article provides an overview of this relay-based technology, focusing on some of the most pertinent aspects. In particular, the different modes of operation (transparent and non-transparent), framing structures, and network entry procedures are described. Some consideration of the issues in designing such systems is then given, which highlights when different features within the standard are most appropriate. As these systems are very new, many open issues remain to be resolved.
284 citations
TL;DR: The IEEE 1451 suite of standards provides a set of standard interfaces for networked smart transducers, helping to achieve sensor plug and play and interoperability for industry and government.
Abstract: This article introduces the IEEE 1451 standard for networked smart transducers. It discusses the concepts of smart transducers, IEEE 1451 smart transducers, the architecture of the IEEE 1451 family of standards, application of IEEE 1451, and example implementations of the IEEE 1451 standards. In conclusion, the IEEE 1451 suite of standards provides a set of standard interfaces for networked smart transducers, helping to achieve sensor plug and play and interoperability for industry and government.
186 citations
TL;DR: An improved mechanism to estimate the available bandwidth in IEEE 802.11-based ad hoc networks is proposed and the accuracy of the estimation is compared to the estimation performed by other state-of-the-art CoS protocols, BRulT, AAC, and CoS-AODV.
Abstract: Since 2005, IEEE 802.11-based networks have been able to provide a certain level of quality of service (QoS) by the means of service differentiation, due to the IEEE 802.11e amendment. However, no mechanism or method has been standardized to accurately evaluate the amount of resources remaining on a given channel. Such an evaluation would, however, be a good asset for bandwidth-constrained applications. In multihop ad hoc networks, such evaluation becomes even more difficult. Consequently, despite the various contributions around this research topic, the estimation of the available bandwidth still represents one of the main issues in this field. In this paper, we propose an improved mechanism to estimate the available bandwidth in IEEE 802.11-based ad hoc networks. Through simulations, we compare the accuracy of the estimation we propose to the estimation performed by other state-of-the-art CoS protocols, BRulT, AAC, and CoS-AODV.
186 citations
TL;DR: The numerical results show that the proposed adaptive GTS allocation (AGA) scheme significantly outperforms the existing IEEE 802.15.4 implementation.
Abstract: IEEE 802.15.4 is a new standard uniquely designed for low-rate wireless personal area networks. It targets ultralow complexity, cost, and power for low-rate wireless connectivity among inexpensive, portable, and moving devices. IEEE 802.15.4 provides a guaranteed time slot (GTS) mechanism to allocate a specific duration within a superframe for time-critical transmissions. This paper proposes an adaptive GTS allocation (AGA) scheme for IEEE 802.15.4, which considers low latency and fairness. The scheme is designed based on the existing IEEE 802.15.4 medium access control protocol, and IEEE 802.15.4 devices can receive this AGA service without any modification. A simulation model and an analytical model are developed to investigate the performance of our AGA scheme. The numerical results show that the proposed scheme significantly outperforms the existing IEEE 802.15.4 implementation.
116 citations
TL;DR: The proposed TEA-15.4 can not only support enough data throughput to carry out multimedia communications, but also offer lower energy consumption for the sensing device in WSNs by adapting the active period based on traffic information.
79 citations
Book•
19 Feb 2008
TL;DR: An in-depth analysis of the recent IEEE 802.15.4 standard for low data rate wireless personal area networks (LR-WPANs), including suggestions to improve performance and comparisons with the related 802.
Abstract: Wireless Personal Area Networks provides an in-depth analysis of the recent IEEE 802.15.4 standard for low data rate wireless personal area networks (LR-WPANs), including suggestions to improve performance and comparisons with the related 802.15.1 (Bluetooth) standard. It assesses the suitability of the standard for the development and deployment of wireless sensor networks as well as providing guidance and insight into the relative advantages and disadvantages of various performance solutions. Wireless Personal Area Networks: Provides a comprehensive, in-depth look at the issues surrounding WPAN network operation and performance. Investigates multi-cluster networks and compares how they can be implemented. Analyzes the performance of a single cluster under different traffic and power management regimes including uplink vs. downlink traffic, acknowledged vs. unacknowledged traffic, saturation vs. non-saturation, and the like. Discusses security issues in WPANs such as different security threats, their impact on performance, standard security mechanisms, and security policies. Compares the IEEE 802.15.4 standard with the related Bluetooth IEEE 802.15.1 standard in terms of suitability for implementing wireless sensor networks. This reference is a valuable tool for developers and researchers getting acquainted with various aspects of IEEE 802.15.4 technology. Graduate students studying courses such as Performance Evaluation, Wireless Sensor Networks and Queuing Theory will also find this book very insightful.
77 citations
21 Apr 2008
TL;DR: The IEEE 802.15.2 Coexistence Mechanisms Alternating Wireless Medium Access Packet Traffic Arbitration Adaptive Packet Selection Packet Scheduling Summary and Concluding Remarks as discussed by the authors.
Abstract: This chapter contains sections titled: Introduction Interference Problem Statement IEEE 802.15.2 Coexistence Mechanisms Alternating Wireless Medium Access Packet Traffic Arbitration Adaptive Packet Selection Packet Scheduling Summary and Concluding Remarks Acknowledgments References
59 citations
15 Apr 2008
TL;DR: A very accurate model for the slotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) access scheme of the IEEE 802.15.4 carrier sensing mechanism is derived and guidelines are derived to optimize the energy or throughput performance of sensor networks using the IEEE802.
Abstract: Advances in low-power and low-cost sensor networks have led to solutions mature enough for use in a broad range of applications, requiring various degrees of reliability. To facilitate this, a broad range of options are possible to tune reliability, throughput or energy cost in the IEEE 802.15.4 standard defining the medium access control (MAC) and physical layer for sensor networks. Knowing how to tune those knobs however requires detailed models of the protocol behavior under different conditions. In our earlier work, we have proposed a very accurate model for the slotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) access scheme of the IEEE 802.15.4 standard for the unacknowledged transmission mode. Because of the design of the 802.15.4 carrier sensing mechanism, modeling the performance of the network in case of acknowledged transmissions is not a trivial extension. In this paper, we hence derive such model and illustrate through simulations that it is extremely accurate. Next, using the model, guidelines are derived to optimize the energy or throughput performance of sensor networks using the IEEE 802.15.4 standard.
TL;DR: This paper investigates the performance of the reference scheduler described in the standard by using a novel queueing analytic framework and proposes a new scheduling scheme, namely, the prediction and optimization-based HCCA (PRO-HCCA), based on the insights gained from the queueing analysis.
Abstract: The IEEE 802.11e standard developed by IEEE 802.11TGe intends to provide the quality of service (QoS) support in IEEE 802.11-based wireless local area networks (WLANs) through the introduction of hybrid coordination function (HCF). The HCF controlled channel access (HCCA) designed as a part of HCF is the medium access mechanism for parameterized QoS and is suitable for multimedia applications requiring hard QoS guarantees. The standard also defines a reference scheduler to complement HCCA in meeting these guarantees. In this paper, we investigate the performance of the reference scheduler described in the standard by using a novel queueing analytic framework. The analysis reveals the performance deficiencies of the reference scheduler. Afterwards, to overcome these deficiencies, we propose a new scheduling scheme, namely, the prediction and optimization-based HCCA (PRO-HCCA), based on the insights gained from the queueing analysis. Simulation experiments show that the proposed scheme overcomes the problems of the reference scheduler and successfully enables the HCCA to fulfill the QoS guarantees for multimedia applications.
TL;DR: STWS enable Web-resident IEEE 1451 smart transducers (sensors and actuators) to be discoverable, accessible, and controllable using Web services via the Internet and to achieve standards-based interoperability for smart transducer applications.
Abstract: This paper describes a unified Web service for IEEE 1451 smart transducers, designated as smart transducer Web services (STWS), developed at the National Institute of Standards and Technology (NIST) based on the IEEE 1451.0 standard. An STWS prototype system developed at NIST consists of a service consumer, service provider (wireless network node), and wireless sensor node. The service consumer and provider communicate with each other through simple object access protocol (SOAP) messages using the IEEE 1451.0 and 1451.5-WiFi interfaces. The prototype system was successfully tested through a few case studies, and a case study of reading transducer data is described in detail. STWS enable Web-resident IEEE 1451 smart transducers (sensors and actuators) to be discoverable, accessible, and controllable using Web services via the Internet and to achieve standards-based interoperability for smart transducer applications.
21 May 2008
TL;DR: The level of interference generated by ongoing transmissions on adjacent channels and thus the level of noise due to cross-channel interference are assessed and an extensive series of measurements are presented in order to assess the performance of IEEE 802.15.4 networks under different critical operating conditions.
Abstract: The growing spread of the IEEE 802.15.4 and ZigBee protocols to support communications in many contexts, such as industrial environments, home and building automation and wireless sensor networks, has led to the deployment of large complex monitoring networks, in which multiple PANs operate in parallel on different channels. In these contexts, network coexistence may be an issue, due to cross-channel interference. This paper addresses cross-channel interference in IEEE 802.15.4 networks. First, reasoning about the coding used by IEEE 802.15.4, we approximately assess the level of interference generated by ongoing transmissions on adjacent channels and thus the level of noise due to cross-channel interference. Secondly, we present and discuss experimental results obtained through an extensive series of measurements, which were run in order to assess the performance of IEEE 802.15.4 networks under different critical operating conditions.
25 Aug 2008
TL;DR: A path selection method for IEEE 802.16j MMR network needs a method for finding the RS route that minimizes the latency and maximizes the network throughput, and the metrics designed for the path selection will be discussed.
Abstract: IEEE 802.16j mobile multi-hop relay (MMR) network provides an attractive solution for the coverage extension and throughput enhancement of IEEE 802.16e network. IEEE 802.16j MMR network needs a method for finding the RS route that minimizes the latency and maximizes the network throughput. In this paper, we propose a path selection method for IEEE 802.16j MMR network. The metrics designed for the path selection, such as link available bandwidth, signal-to-noise ratio (SNR) and hop count will be discussed. We demonstrate the performance improvement with numerical results.
TL;DR: The Project Authorization Request for the IEEE P1900.4 Working Group (WG), under the IEEE Standards Coordinating Committee 41 (SCC41) was approved in December 2006, leading to this WG being officially launched in February 2007.
Abstract: The Project Authorization Request (PAR) for the IEEE P1900.4 Working Group (WG), under the IEEE Standards Coordinating Committee 41 (SCC41) was approved in December 2006, leading to this WG being officially launched in February 2007 [1]. The scope of this standard is to devise a functional architecture comprising building blocks to enable coordinated network-device distributed decision making, with the goal of aiding the optimization of radio resource usage, including spectrum access control, in heterogeneous wireless access networks. This paper introduces the activities and work under progress in IEEE P1900.4, including its scope and purpose in Sects. 1 and 2, the reference usage scenarios where the standard would be applicable in Sect. 4, and its current system architecture in Sect. 5.
16 Jun 2008
TL;DR: This paper studies the problem of scheduling MDAOPs, which is left unspecified by the standard, and proposes two baseline algorithms, and provides evidence that performance under MDA can be significantly degraded by the unknown interference of traffic flows outside the two-hop neighborhood.
Abstract: Deployment of Wireless Mesh Networks (WMNs) is becoming increasingly popular due to the low-impact and low- cost features of wireless devices. This is especially true for WMNs based on IEEE 802.11 which, however, does not include native support for multi-hop relaying. This gap is being filled by the Task Group 's' of the IEEE 802.11 which has recently published an amendment in order to add mesh functions to the popular standard IEEE 802.11. Among the enhancements proposed, Mesh Deterministic Access (MDA) allows mesh routers to negotiate periodic collision-free transmission opportunities, called MDAOPs, to the Medium Access Control (MAC) layer on a hop- by-hop manner. Control messages are exchanged to advertise the reserved MDAOPs in the two-hop neighborhood. MDA lays the foundations for enabling QoS provisioning functions in IEEE 802.11s WMNs, such as end-to-end bandwidth reservation, call admission control, and traffic engineering. In this paper we study the problem of scheduling MDAOPs, which is left unspecified by the standard, and propose two baseline algorithms. Furthermore, we provide evidence that performance under MDA can be significantly degraded by the unknown interference of traffic flows outside the two-hop neighborhood. A dynamic relocation procedure is proposed in order to combat this phenomenon, thus providing traffic flows established in the WMN with stable performance. This procedure does not need any modifications to the standard MDA procedure. To the best of our knowledge, this is the first study that tackles this problem in the context of IEEE 802.11s. The effectiveness of the proposed algorithms is evaluated by means of a packet-level simulation.
01 Feb 2008
TL;DR: A distributed AP selection algorithm for newly joining MU and already associated MUs to be adaptive to their joining order and the dynamic wireless environment is proposed and can greatly improve the fairness without significantly sacrificing the efficiency.
Abstract: For the mobile users (MUs) installed with IEEE 802.11 wireless adapters, the default best-signal-strength-based access point (AP) selection is limited since it does not consider fairness and multi-rate issues. In this paper, we propose a distributed AP selection algorithm for newly joining MU and already associated MUs to be adaptive to their joining order and the dynamic wireless environment. We also prove the stability of proposed algorithm and analyze its complexity. Finally, with extensive evaluations, we show that proposed scheme can greatly improve the fairness without significantly sacrificing the efficiency.
TL;DR: In this article, potential problems with the energy consumption in sensor networks using IEEE 802.15.4 are discussed and six representative categories of algorithms are presented.
Abstract: IEEE 802.15.4 is the global standard protocol designed for low-power and low-rate wireless personal area networks. When applied to sensor networks, extra care should be taken due to their requirements for multihop communication with minimum energy consumption. In this article we first discuss potential problems with the energy consumption in sensor networks using IEEE 802.15.4. Then six representative categories of algorithms are presented. The algorithms reside in between the MAC and a network layer. All operations of the MAC are performed through the standard interfaces of IEEE 802.15.4 without altering the standard protocol. The energy consumption and latency of the algorithms are evaluated by analysis and experiments, and the feasibility of real implementations is also discussed.
17 Nov 2008
TL;DR: Results show that the H.264/SVC codec particularly benefits from the proposed algorithm, which enables a graceful video quality degradation in congested network conditions, as well as PSNR gains up to 2 dB with respect to the H264/AVC codec using the same amount of network resources.
Abstract: The H.264/SVC video codec extends the H.264/AVC standard with scalability features. In this paper we introduce a traffic prioritization algorithm suitable for the transmission of both H.264/SVC and H.264/AVC video over 802.11e ad hoc wireless networks. The proposed algorithm exploits the traffic prioritization capabilities offered by 802.11e to provide better protection to the most perceptually important parts of a video while achieving efficient network resource usage. We evaluate the algorithm by simulating video transmissions in an ad hoc network scenario. Results show that the H.264/SVC codec particularly benefits from the proposed algorithm, which enables a graceful video quality degradation in congested network conditions, as well as PSNR gains up to 2 dB with respect to the H.264/AVC codec using the same amount of network resources.
TL;DR: Simulation results show that this scheme is able to meet the QoS requirements of the service flows of the uplink traffic and is fully standard-compliant and can be easily implemented in the base station.
Abstract: 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.
TL;DR: This paper defends that a balanced distribution of mobile stations among the available access points leads to better performances of the Wireless LAN and proposes a QoS management solution for wireless communication systems.
Abstract: With the 802.11 WLAN multimedia applications (Video, Audio, real-time voice over IP,…) increasing, providing Quality of Service (QoS) support becomes very important since the original standard doesn’t take QoS into account. The standard offers access to the wireless users only regarding physical considerations. This can lead to overloaded access points (AP) and considerable degradation of the QoS. This paper deals with this problem. It focuses on the presentation of a QoS management solution for wireless communication systems. It mainly defends that a balanced distribution of mobile stations among the available access points leads to better performances of the Wireless LAN. Some OPNET simulations of the proposed approach are presented to show a better resources allocation and efficiency on QoS metrics. A protocol structure between mobiles and APs is also specified for the implementation of this approach. An SDL description and MSC simulation of this protocol is provided as a first step in its development.
01 Jan 2008
TL;DR: 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.
Abstract: 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.
TL;DR: A multi-dimensional Markov Chain model is introduced that faithfully represents the functionality of the EDCA access mechanisms, including lesser known details of the standard such as the management of the backoff counter which is technically different from the one used in the legacy DCF.
Abstract: In this paper we study the performance of IEEE 802.11e enhanced distributed channel access (EDCA) priority schemes under finite load and error-prone channel. We introduce a multi-dimensional Markov Chain model that includes all the mandatory differentiation mechanisms of the standard: QoS parameters, CWMIN, CWMAX arbitration inter-frame space (AIFS), and the virtual collision handler. The model faithfully represents the functionality of the EDCA access mechanisms, including lesser known details of the standard such as the management of the backoff counter which is technically different from the one used in the legacy DCF. We study the priority schemes under both finite load and saturation conditions. Our analysis also takes into consideration channel conditions.
03 Mar 2008
TL;DR: A performance evaluation of the IEEE 802.11e technology on Mobile Ad-hoc Networks (MANETs) in both stationary and mobile scenarios is focused on, and the conclusion that the behavior of both simulators is quite similar in general is reached.
Abstract: In this work we present the results of a comparative study between two well-known network simulators: ns-2 and OP-NET Modeler. In particular, we focus on a performance evaluation of the IEEE 802.11e technology on Mobile Ad-hoc Networks (MANETs) in both stationary and mobile scenarios. The paper describes the tested scenarios in detail, and discusses simulation results obtained with OPNET Modeler, comparing them with those obtained with ns-2. The performance of IEEE 802.11e in the presence of legacy IEEE 802.11 stations is also analyzed. Due to the significant differences between both simulators, we enumerate those changes required so as to make results obtained via both simulators comparable. The results that have been reached support the conclusion that the behavior of both simulators is quite similar in general.
15 May 2008
TL;DR: Through extensive simulations, performance of the proposed medium access control (MAC) enhancement is evaluated showing its remarkable efficiency and better wireless medium access management.
Abstract: In this paper, we propose a novel distributed frequency agile medium access control (MAC) extension to the IEEE 802.11s amendment for the next generation wireless mesh networks (WMNs). The proposed scheme has complete backward compatibility with the legacy IEEE 802.11 and the emerging 802.11s while, it is perfectly capable of multi-channel deployment of available frequency opportunities in order to coordinate concurrent multiple data transmissions. The root concept of the proposed enhancement is mainly based on the deployment of well-known ISM frequency bands, where the existing 802.11-based wireless equipments nowadays operate, as the common control channel in order to establish concurrent data transmissions. Here, we apply the aforementioned key concept to the IEEE 802.11s common channel framework (CCF) to attain two important goals: on one hand, the proposed scheme improves the channel utilization and capacity using the concept of cognitive radio and on the other hand, using the same concept it leads to lower access delay due to smarter decision making procedures exploited for link layer connection establishment. Through extensive simulations, which also take into account primary user (PU) appearance in non-ISM frequency opportunities, performance of the proposed medium access control (MAC) enhancement is evaluated showing its remarkable efficiency and better wireless medium access management.
25 Mar 2008
TL;DR: The idea to implement some scheduling schemes on WiMAX system in NS2 to analysis in uplink and downlink direction to get better performance for the IEEE 802.16 system is implemented.
Abstract: In the last years, demand for high-speed Internet access and multimedia service has increased greatly. The IEEE 802.16 Working Group on broadband wireless access is developing the IEEE 802.16 standards for wireless metropolitan area networks. IEEE 802.16 aims at providing broadband wireless last-mile access in a Metropolitan Area Network, easy deployment, high speed data rate and large spanning area. WiMAX also support quality of service architecture include priority scheduling and queuing for bandwidth allocation to support our system more efficient. Therefore, we have an idea to implement some scheduling schemes on WiMAX system in NS2 to analysis in uplink and downlink direction to get better performance. By simulation results, it can show the performance of different scheduling schemes clearly, and which one suit for different specific environment. Finally, we can support an efficient Queuing scheduling theory on dynamic bandwidth allocation to get better performance for the IEEE 802.16 system.
TL;DR: This paper proposes a mechanism combining service differentiation and packet aggregation in IEEE 802.11-based WMNs that does not require any modification to the IEEE802.11 MAC and can be readily deployed exploiting off-the-shelf hardware.
16 Jun 2008
TL;DR: This paper design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluates its performance using UDP streaming and HTTP download to point out importance of higher layer coordination with lower layers for end-to-end performance improvements in cognitive wireless networks.
Abstract: IEEE P1900.4 is an emerging standard for optimized radio resource utilization where cognitive radio technologies are used for efficient spectrum utilization. In this paper, we design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluate its performance using UDP streaming and HTTP download. Our experiments show interesting results that total network throughput in the HDP streaming is improved by 30% although some of individual terminals can not necessarily obtain better throughput. Also, it is shown that performance in the HTTP download becomes worse by up to about 40% as the number of handover increases due to the TCP window control. Our analysis is expected to point out importance of higher layer coordination with lower layers for end-to-end performance improvements in cognitive wireless networks.
15 Aug 2008
TL;DR: A new handover algorithm for deployment in 802.11e- capable stations is proposed that takes into consideration the main important aspects of IEEE 802.16 operation such as ranging, authorization, and registration.
Abstract: Supporting mobility is both promising and challenging feature of the emerging IEEE 802.16e wireless networks, commonly known as WiMAX. Although the IEEE has released an amendment to the original IEEE 802.16 standard in which mobility and handover are added as basic capabilities, the amended standard (IEEE 802.16e) defines only a frame work without providing specific methods or algorithm for handover that can be deployed in mobile stations to enable them to switch seamlessly from one base station to another. In this paper, we propose a new handover algorithm for deployment in 802.11e- capable stations. The algorithm takes into consideration the main important aspects of IEEE 802.16 operation such as ranging, authorization, and registration. A special capability built into the proposed algorithm is service-flows awareness, i.e. the algorithm tries to minimize the the time spent in handover based on the service flows running at the mobile station. Analysis of the proposed algorithm shows that handover time can be reduced by several folds by taking advantage of different capabilities provided by the standard.