Download or read book QoS Provisioning for IEEE 802 11 MAC Protocols written by Ye Ge and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this dissertation, we investigate the issue of Quality of Service (QoS) provisioning for IEEE 802.11 MAC protocols. We propose a multiple class p-persistent version of the IEEE 802.11 protocol to support QoS differentiation in wireless local area networks (WLANs). A theoretical analysis model is proposed to predict the performance of this protocol. Through analytical modeling and simulation, we demonstrate that by assigning appropriate different transmission probabilities to wireless nodes of different classes, it is feasible to provide service differentiation and achieve the targeted throughput ratio among different classes, while at the same time, maximizing the total channel utilization. We also consider several implementation issues to practically implement the proposed work conforming to the IEEE 802.11 standard. In particular, we derive an approximate solution for the analytical model to reduce the computational complexity and estimate the performance deterioration due to such an approximate solution. We point out that as long as the average packet collision period is much longer than the basic slot duration in the backoff algorithm, (which is true in all the 802.11 family standards such as 802.11, 802.11b, 802.11a and 802.11g, as well as many potential new systems with higher transmission rates,) the loss in channel utilization is limited when the approximate solution is used to determine the protocol parameters. We associate the contention window based backoff scheme in the current 802.11 mac protocol to the proposed p-persistent MAC protocol through a simple relation between the contention window, $cw$, and the persistent probability, p. We also propose a simple yet effective mechanism to on-line estimate the number of active stations in a QoS basic service set (QBSS) so as to handle the network dynamics and optimize system parameters dynamically. By extending the analytical model, we study the impact of AIFS values in IEEE 802.11e on rate differentiation between different traffic classes, demonstrate that the per flow throughput ratio between different traffic classes is a function of both the persistent probability (or the contention window size) and AIFS values. Under the asymptotic condition, we derive a closed-form relation. Through analytical modeling and simulation, we evaluate the effect of tuning AIFS values to provide throughput differentiation. We recommend to only adjust the persistent probability p or equivalently the contention window size cw to achieve the desired rate differentiation, while keeping the AIFS values of all traffic classes to the same value (e.g., at DIFS). This keeps the dimension of design freedom small and the parameter fine-tuning process tractable.

Download or read book A New Framework for QoS Provisioning in Wireless LANs Using the P Persistent MAC Protocol written by Kiran Babu Anna and published by . This book was released on 2010 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: The support of multimedia traffic over IEEE 802.11 wireless local area networks (WLANs) has recently received considerable attention. This dissertation has proposed a new framework that provides efficient channel access, service differentiation and statistical QoS guarantees in the enhanced distributed channel access (EDCA) protocol of IEEE 802.11e. In the first part of the dissertation, the new framework to provide QoS support in IEEE 802.11e is presented. The framework uses three independent components, namely, a core MAC layer, a scheduler, and an admission control. The core MAC layer concentrates on the channel access mechanism to improve the overall system efficiency. The scheduler provides service differentiation according to the weights assigned to each Access Category (AC). The admission control provides statistical QoS guarantees. The core MAC layer developed in this dissertation employs a P-Persistent based MAC protocol. A weight-based fair scheduler to obtain throughput service differentiation at each node has been used. In wireless LANs (WLANs), the MAC protocol is the main element that determines the efficiency of sharing the limited communication bandwidth of the wireless channel. In the second part of the dissertation, analytical Markov chain models for the P-Persistent 802.11 MAC protocol under unsaturated load conditions with heterogeneous loads are developed. The Markov models provide closed-form formulas for calculating the packet service time, the packet end-to-end delay, and the channel capacity in the unsaturated load conditions. The accuracy of the models has been validated by extensive NS2 simulation tests and the models are shown to give accurate results. In the final part of the dissertation, the admission control mechanism is developed and evaluated. The analytical model for P-Persistent 802.11 is used to develop a measurement-assisted model-based admission control. The proposed admission control mechanism uses delay as an admission criterion. Both distributed and centralized admission control schemes are developed and the performance results show that both schemes perform very efficiently in providing the QoS guarantees. Since the distributed admission scheme control does not have a complete state information of the WLAN, its performance is generally inferior to the centralized admission control scheme. The detailed performance results using the NS2 simulator have demonstrated the effectiveness of the proposed framework. Compared to 802.11e EDCA, the scheduler consistently achieved the desired throughput differentiation and easy tuning. The core MAC layer achieved better delays in terms of channel access, average packet service time and end-to-end delay. It also achieved higher system throughput than EDCA for any given service differentiation ratio. The admission control provided the desired statistical QoS guarantees.

Download or read book Quality of Service Provisioning with Modified IEEE 802 11 MAC Protocol written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been a phenomenal increase in the demand of quality-of-service (QoS) in wireless networks over the years due to rapid growth in the number of wireless and mobile devices. Such devices are in use to access Internet and QoS aware applications such as video conferencing, voice-over IP, interactive video-on-demand and many other multimedia applications. wireless local area networks (WLANs) confirming to the IEEE 802.11 standard have become extremely popular at an unprecedented rate. As a result, WLAN networks are gaining the momentum and making their way into residential, commercial, industrial and public areas. These trends are more and more accelerated in places like airports, hotels and coffee shop, this typically has many floating end users. The time stringent applications are delay sensitive that require throughput and delay bound creates an urgent need for QoS support in WLANs.

Download or read book Fundamental Concepts on Wireless LAN and the IEEE 802 11 Protocol written by Dereje Yohannes Ashenafi and published by Dereje Yohannes. This book was released on 2011 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book QoS Provisioning Via Cooperative Medium Access Protocol in Wireless Networks written by Fatma Orsun and published by . This book was released on 2005 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Author's abstract] Short term fairness, low delay jitter and high throughput are required to provide differentiated Quality of Service (QoS) levels in wireless ad hoc networks and wireless Local Area Networks (LAN). This thesis presents a study of differentiated service mechanism via Cooperative Medium Access Protocol in wireless LANs. The IEEE 802.11 MAC can provide service differentiation via Point Coordination Function (PCF) by polling or Distributed Coordination Function (DCF) by Static Priority (SP) and Dynamic Priority (DP). The DP and PCF in highly loaded networks and SP in lightly loaded networks perform poorly and can not support QoS levels of wireless LANs efficiently. This thesis proposes a novel and efficient differentiated service mechanism via Cooperative Medium Access Control (C MAC). Proposed mechanism performs very well under both cases, highly loaded and lightly loaded. It protects high priority classes from greedy sources while providing short term fairness within the priority classes and high network goodput. However, it encounters a small amount of additional packet loss and goodput degradation and it requires additional counter, Backoff Increment Counter, and additional knowledge, priority level of the transmitted packet.

Download or read book Advances in Computer Information and Systems Sciences and Engineering written by Khaled Elleithy and published by Springer Science & Business Media. This book was released on 2007-06-06 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conference proceedings of: International Conference on Industrial Electronics, Technology & Automation (IETA 05) International Conference on Telecommunications and Networking (TeNe 05) International Conference on Engineering Education, Instructional Technology, Assessment, and E-learning (EIAE 05) include a set of rigorously reviewed world-class manuscripts addressing and detailing state-of-the-art research projects in the areas of: Industrial Electronics, Technology and Automation, Telecommunications, Networking, Engineering Education, Instructional Technology and e-Learning. The three conferences, (IETA 05, TENE 05 and EIAE 05) were part of the International Joint Conference on Computer, Information, and System Sciences, and Engineering (CISSE 2005). CISSE 2005, the World's first Engineering/Computing and Systems Research E-Conference was the first high-caliber Research Conference in the world to be completely conducted online in real-time via the internet. CISSE received 255 research paper submissions and the final program included 140 accepted papers, from more than 45 countries. The whole concept and format of CISSE 2005 was very exciting and ground-breaking. The powerpoint presentations, final paper manuscripts and time schedule for live presentations over the web had been available for 3 weeks prior to the start of the conference for all registrants, so they could pick and choose the presentations they want to attend and think about questions that they might want to ask. The live audio presentations were also recorded and are part of the permanent CISSE archive, which includes all power point presentations, papers and recorded presentations. All aspects of the conference were managed on-line; not only the reviewing, submissions and registration processes; but also the actual conference. Conference participants - authors, presenters and attendees - only needed an internet connection and sound available on their computers in order to be able to contribute and participate in this international ground-breaking conference. The on-line structure of this high-quality event allowed academic professionals and industry participants to contribute work and attend world-class technical presentations based on rigorously refereed submissions, live, without the need for investing significant travel funds or time out of the office. Suffice to say that CISSE received submissions from more than 50 countries, for whose researchers, this opportunity presented a much more affordable, dynamic and well-planned event to attend and submit their work to, versus a classic, on-the-ground conference. The CISSE conference audio room provided superb audio even over low speed internet connections, the ability to display PowerPoint presentations, and cross-platform compatibility (the conferencing software runs on Windows, Mac, and any other operating system that supports Java). In addition, the conferencing system allowed for an unlimited number of participants, which in turn granted CISSE the opportunity to allow all participants to attend all presentations, as opposed to limiting the number of available seats for each session. The implemented conferencing technology, starting with the submission & review system and ending with the online conferencing capability, allowed CISSE to conduct a very high quality, fulfilling event for all participants. See: www.cissee2005.org, sections: IETA, TENE, EIAE

Download or read book Quality of Service Provisioning Scheme for Real time Applications in IEEE 802 11 Wireless Local Area Network written by Roger Cheng Yong Ng and published by . This book was released on 2006 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a novel quality of (QoS) provisioning scheme for real-time applications in IEEE 802.11e wireless local area networks (WLAN). The emerging 802.11e standard is tackling the exploding volume of traffic in WLANs with a long-term solution based on QoS-architectures. QoS delivers predictability and consistency into existing variability of best-effort delivery system offered in internet protocol (IP) and IEEE 802.11 wireless networks. Service differentiation in WLAN networks is achieved by means of assigning packets (from the network layer) to different access catogories (AC), a set of fixed medium access control (MAC) level parameters that defines the priority echelon for each AC. Thus real-time applications are assigned higher priority ACs to ensure better service and to ensure that the delay constraints of these applications are promptly dealth with. An algorithm called Slide and Translate (SNT) is proposed for IEEE 802.11 WLANs. The SNT adapts contention parameters of individual ACs based on the network load in a basic service set (BSS). SNT is derived from the observation of the success and failures of previously proposed QoS provisioning schemes. The SNT adapts the backoff interval, minimum contention window (CW min) and contention offset (CW offset) to ensure the QoS constraints for the different ACs are dealt with. To further understand the SNT, a simple mathematical analysis is presented on the inter-AC differentiation characteristics; subsequentl, through simulation it is shown that SNT is able to maintain high medium utilisation over wide range of offered loads while providing a high degree of isolation (in terms of throughput, delay and frame loss) to high priority traffic. Further to this, an extension to the SNT called SNT-AC is proposed in order to achieve efficient end-to-end resource provisioning. SNT-AC uses an admission control algorithm to restrict flows in and out of the BSS. The admission controller resides in the IP layer and makes decision based on the MAC level feedback. The simulation results indicate that the close coupling QoS coordination can ensure both bandwidth and latency to admitted flows by controlling the effective offered load into the BSS. This guarantees high prioriyu ACs protection against overwhelming traffic in a WLAN. Finally a brief discussion on future directions of WLANs and hardware implementation issues conclude the thesis.

Download or read book Provision of QoS for Multimedia Services in IEEE 802 11 Wireless Network written by and published by . This book was released on 2006 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Implementation of the IEEE 802.11 technology for wireless local area networks (WLANs) has created a new opportunity to support real time and multimedia applications. The IEEE 802.11 defines a Medium Access Control (MAC), and Physical Layers (PHYs), which provides rates from 1 to 54 Mbit/s depending on specification. In IEEE 802.11 network, the PHY rate to be used for the transmission is completely determined by the source node and is closely connected with the wireless channel performance. The varying nature of WLAN channel over time can degrade the QoS level of multimedia service, which calls for elaboration of advanced QoS mechanism supporting multimedia services. The research works applied to video transmission over WLAN mostly concentrate on using a link adaptation techniques or optimisation of video stream by cross-layer signalling. It appears to be not sufficient as far as a provision of QoS for multimedia services is considered. In the paper, a new mechanism of QoS enhancement respecting also modifications in transport and network layers is discussed. A general description of this mechanism is presented with special emphasize on new approach to the multimedia rate control. The paper covers the verification of the proposal by simulation method as well as a discussion of some selected results of simulation.

Download or read book Enabling Techniques Design for QoS Provision in Wireless Communications written by Penghui Mi and published by . This book was released on 2012 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Guaranteeing Quality of Service (QoS) has become a recognized feature in the design of wireless communications. In this thesis, the problem of QoS provision is addressed from di erent prospectives in several modern communication systems. In the first part of the thesis, a wireless communication system with the base station (BS) associated by multiple subscribers (SS) is considered, where di erent subscribers require di erent QoS. Using the cross-layer approach, the conventional single queue finite state Markov chain system model is extended to multiple queues' scenario by combining the MAC layer queue status with the physical layer channel states, modeled by finite state Markov channel (FSMC). To provide the diverse QoS to di erent subscribers, a priority-based rate allocation (PRA) algorithm is proposed to allocate the physical layer transmission rate to the multiple medium access control (MAC) layer queues, where di erent queues are assigned with di erent priorities, leading to their di erent QoS performance and thus, the diverse QoS are guaranteed. Then, the subcarrier allocation in multi-user OFDM (MU-OFDM) systems is stuied, constrained by the MAC layer diverse QoS requirements. A two-step cross-layer dynamic subcarrier allocation algorithm is proposed where the MAC layer queue status is firstly modeled by a finite state Markov chain, using which MAC layer diverse QoS constraints are transformed to the corresponding minimum physical layer data rate of each user. Then, with the purpose of maximizing the system capacity, the physical layer OFDM subcarriers are allocated to the multiple users to satisfy their minimum data rate requirements, which is derived by the MAC layer queue status model. Finally, the problem of channel assignment in IEEE 802.11 wireless local area networks (WLAN) is investigated, oriented by users' QoS requirements. The number of users in the IEEE 802.11 channels is first determined through the number of di erent channel impulse responses (CIR) estimated at physical layer. This information is involved thereafter in the proposed channel assignment algorithm, which aims at maximum system throughput, where we explore the partially overlapped IEEE 802.11 channels to provide additional frequency resources. Moreover, the users' QoS requirements are set to trigger the channel assignment process, such that the system can constantly maintain the required QoS.

Download or read book Personal Wireless Communications Pwc 05 Proceedings Of The 10th Ifip Conference written by Pascal Lorenz and published by World Scientific. This book was released on 2005-07-07 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 10th IFIP International Conference on Personal Wireless Communications covers a wide spectrum: wireless sensors, signalization, traffic and QoA in wireless networks, Ad-Hoc, IEEE 802.11, cellular and mobile networks. This volume offers a large range of solutions to key problems in wireless networking and explores challenging avenues for industrial research and development. It is accessible to engineers, practitioners, and scientists as well as industry professionals from manufacturers to service providers.

Download or read book Quality of Service Architectures for Wireless Networks Performance Metrics and Management written by Adibi, Sasan and published by IGI Global. This book was released on 2010-01-31 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book further explores various issues and proposed solutions for the provision of Quality of Service (QoS) on the wireless networks"--Provided by publisher.

Download or read book MAC Layer QoS Evaluation Metrics for IEEE 802 11e EDCF Protocol Over Nodes Mobility Constraints written by Khaled Dridi and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: MAC-Layer QoS Evaluation Metrics for IEEE 802.11e-EDCF Protocol over Nodes' Mobility Constraints.

Download or read book Distributed Medium Access Control for QoS Support in Wireless Networks written by Ping Wang and published by . This book was released on 2008 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the rapid growth of multimedia applications and the advances of wireless communication technologies, quality-of-service (QoS) provisioning for multimedia services in heterogeneous wireless networks has been an important issue and drawn much attention from both academia and industry. Due to the hostile transmission environment and limited radio resources, QoS provisioning in wireless networks is much more complex and difficult than in its wired counterpart. Moreover, due to the lack of central controller in the networks, distributed network control is required, adding complexity to QoS provisioning. In this thesis, medium access control (MAC) with QoS provisioning is investigated for both single- and multi-hop wireless networks including wireless local area networks (WLANs), wireless ad hoc networks, and wireless mesh networks. Originally designed for high-rate data traffic, a WLAN has limited capability to support delay-sensitive voice traffic, and the service for voice traffic may be impacted by data traffic load, resulting in delay violation or large delay variance. Aiming at addressing these limitations, we propose an efficient MAC scheme and a call admission control algorithm to provide guaranteed QoS for voice traffic and, at the same time, increase the voice capacity significantly compared with the current WLAN standard. In addition to supporting voice traffic, providing better services for data traffic in WLANs is another focus of our research.

Download or read book An Efficient QoS MAC for IEEE 802 11p Over Cognitive Multichannel Vehicular Networks written by Hikmat El Ajaltouni and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wireless Internet and Mobile Computing written by Yu-Kwong Ricky Kwok and published by John Wiley & Sons. This book was released on 2007-08-24 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the technologies involved in all aspects of a large networking system and how the various devices can interact and communicate with each other. Using a bottom up approach the authors demonstrate how it is feasible, for instance, for a cellular device user to communicate, via the all-purpose TCP/IP protocols, with a wireless notebook computer user, traversing all the way through a base station in a cellular wireless network (e.g., GSM, CDMA), a public switched network (PSTN), the Internet, an intranet, a local area network (LAN), and a wireless LAN access point. The information bits, in travelling through this long path, are processed by numerous disparate communication technologies. The authors also describe the technologies involved in infrastructure less wireless networks.

Download or read book Networking Infrastructure for Pervasive Computing written by Debashis Saha and published by Springer Science & Business Media. This book was released on 2003 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors (two of whom are from the Indian Institute of Management Calcutta, India) argue that the possibilities of "Pervasive Computing" promises to extend the information-networked environment to practically every technological device, but that the current networking and communication infrastructure doesn't support those possibilities. Largely concerning themselves with networking technologies, they provide advice on the problems of addressing this gap between promise and infrastructure. Annotation (c)2003 Book News, Inc., Portland, OR (booknews.com).

Download or read book MIMO aware Medium Access Control in IEEE 802 11 Networks written by Abduladhim Mabruk Ashtaiwi and published by . This book was released on 2009 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless Mesh Networks (WMNs) are dynamically self-organized and self-configured, where the nodes in the network automatically establish an ad hoc network and maintain mesh connectivity. These properties make WMNs a key technology for next generation wireless networking. However, supporting Quality of Service (QoS) to enable multimedia services is still one of the major issues in next-generation WMNs. In distributed systems like WMNs, the Medium Access Control (MAC) layer is considered very important in the IEEE 802.11-based wireless networks, as it supports many crucial operational functions. Hence, QoS support in WMNs can be enhanced through the efficient cross-layer design of MAC protocols that utilizes advanced physical layer technologies viz Multiple-Input Multiple-Output (MIMO) with its multiple spatial channels that are capable of simultaneous receive or transmit streams. MIMO has become a very attractive technology in providing support for different QoS requirements. In this thesis we propose a novel QoS MIMO-aware MAC Protocol (QMMP). QMMP is a MAC protocol framework that exploits the MIMO system gains to boost QoS support. The proposed MAC framework includes the following components. The first component enables concurrent sharing of the increased MIMO bandwidth, i.e., instead of allocating all the spatial channels to one connection, connections can concurrently share the increase bandwidth via splitting the spatial channels. The second component reduces the medium access collisions problem. In distributed systems like WMNs, medium access collisions have a noticeably negative impact on resource (bandwidth) utilization as they leave the bandwidth unutilized for a long time. To address this problem, we propose a spatial channels sharing scheme during medium contention period. The third component boosts the bandwidth utilization during data transmission. We propose resource management schemes that adapt the physical data rate and the aggregation frame length according to the instantaneous channel quality. Then we propose a QoS-aware bandwidth provisioning mechanism that performs effective bandwidth distribution to further boost QoS support.