Download or read book Joint Optimization of Medium Access Control and Adaptive Modulation and Coding for Wireless Networks with Multipacket Reception written by Shih-Yuan Liu and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Medium Access Control and Adaptive Transmission Techniques in Wireless Networks written by and published by . This book was released on 2005 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficient utilization of the limited wireless spectrum while satisfying applications' quality of service requirements is an essential design goal of forthcoming wireless networks and a key to their successful deployment. The need for spectrally efficient systems has motivated the development of adaptive transmission techniques. Enabling this adaptation requires protocols for information exchange as well as mathematical tools to optimize the controllable parameters. In this dissertation, we provide insights into such protocols and mathematical tools that target efficient utilization of the wireless spectrum. First, we propose a distributed CDMA-based medium access protocol for mobile ad hoc networks (MANETs). Our approach accounts for multiple access interference at the protocol level, thereby addressing the notorious near-far problem that undermines the throughput performance in MANETs. Second, we present a novel power-controlled MAC protocol, called POWMAC, which enjoys the same single-channel, single-transceiver design of the IEEE 802.11 Ad Hoc MAC protocol, but which achieves a significant throughput improvement over the 802.11 protocol. Third, we consider joint power/rate optimization in the context of orthogonal modulation (OM) and investigate the performance gains achieved through adaptation of the OM order using recently developed optimization techniques. We show that such adaptation can significantly increase network throughput while simultaneously reducing the per-bit energy consumption relative to fixed-order modulation systems. Finally, we determine the maximum achievable p̀̀erformance" of a wireless CDMA network that employs a conventional matched filter receiver and that operates under \emph{optimal} link-layer adaptation where each user individually achieves the Shannon capacity. The derived bounds serve as benchmarks against which adaptive CDMA systems can be compared.

Download or read book Protocol Design and Optimization for Wireless Networks written by Monchai Lertsutthiwong and published by . This book was released on 2010 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate a number of techniques for increasing throughput and quality of media applications over wireless networks. A typical media communication application such as video streaming imposes strict requirements on the delay and throughout of its packets, which unfortunately, cannot be guaranteed by the underlying wireless network due inherently to the multi-user interference and limited bandwidth of wireless channels. Therefore, much recent research has been focused on the joint design of network layers in order to guarantee some pre-specified Quality of Service (QoS). In this thesis, we investigate three specific settings to address the general problem of media transmission over wireless networks. In the first setting, we propose a distributed admission control algorithm in one-hop wireless network to decide whether or not a new flow should be injected into the network, in order to guarantee the QoS of the current flows. Next, a novel medium access control protocol and a scheduling packet algorithm are proposed for jointly optimizing the quality of video streaming applications. In the second setting, we extend the framework of the proposed admission control from a one-hop network to linear wireless networks, consisting of multiple nodes. In the third and final setting, we present an approach for increasing the throughput of wireless access networks by integrating network coding and beamforming techniques.

Download or read book Multiple Access Communications written by Alexey Vinel and published by Springer. This book was released on 2010-09-08 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is our great pleasure to present the proceedings of the Third International Workshop on Multiple Access Communications (MACOM) that was held in Barcelona during September 13–14, 2010. In 1961, Claude Shannon established the foundation for the discipline now known as “multi-user information theory” in his pioneering paper “Two-way Communication Channels,” and later Norman Abramson published his paper “The Aloha System—Another Alternative for Computer Communications” in 1970 which introduced the concept of multiple access using a shared common channel. Thereafter, for more than 40 years of study, numerous elegant theories and algorithms have been developed for multiple-access communications. During the 1980s and 1990s the evolution of multiple-access techniques p- ceeded in conjunction with the evolution of wireless networks. Novel multiple access techniques like code division multiple access (CDMA) and orthogonal frequency division multiple access (OFDMA) provided increased spectral - ?ciency, dynamicity and ?exibility in radio resource allocation with intrinsic anti-multipath and anti-interference features. In this ?rst decade of the 21st century,multiple-accesstechniques,derivedfromadvancedwirelesstransmission methodologiesbasedonthediversityconcept(e. g. ,MC-CDMA,MIMO-OFDMA and SC-FDMA), opened the road to a renewed idea of multiple access. Today multiple-access communications involve many challenging aspects not only l- ited (like in the past) to physical layer design. Medium access control (MAC) techniques play a crucial role in managing the radio resources that users will exploit to transmit their data streams. Recent developments in software radios and cognitive radios have led to a signi?cant impact also on spectrum m- agement and access paradigms.

Download or read book Distributed Medium Access Control in Wireless Networks written by Ping Wang and published by Springer. This book was released on 2013-03-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This brief investigates distributed medium access control (MAC) with QoS provisioning for both single- and multi-hop wireless networks including wireless local area networks (WLANs), wireless ad hoc networks, and wireless mesh networks. For WLANs, an efficient MAC scheme and a call admission control algorithm are presented 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, a novel token-based scheduling scheme is proposed to provide great flexibility and facility to the network service provider for service class management. Also proposed is a novel busy-tone based distributed MAC scheme for wireless ad hoc networks and a collision-free MAC scheme for wireless mesh networks, respectively, taking the different network characteristics into consideration. The proposed schemes enhance the QoS provisioning capability to real-time traffic and, at the same time, significantly improve the system throughput and fairness performance for data traffic, as compared with the most popular IEEE 802.11 MAC scheme.

Download or read book On Channel Access Design for Wireless Networks with Multi packet Reception written by Ke Li and published by . This book was released on 2015 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: As wireless devices have emerged as a ubiquitous part of people's everyday lives, the demands for faster wireless communications become even more pressing. Fortunately, the advanced techniques of the physical layer such as multiple-input and multiple-output (MIMO), multi-user detection (MUD), advanced modulation, etc., make multi-packet transmission (MPT) and multi-packet reception (MPR) possible. It has been well recognized that the MPT/MPR technique can improve the performance of the wireless networks. However, novel algorithms at the medium-access control (MAC) and higher layers are needed to fully exploit the MPT/MPR capability. In this thesis, we study the behavior the MPT/MPR wireless network, evaluate its potential performance and design algorithms to efficiently and fairly manage the MPT/MPR networks. We start from a single-hop scenario where uncoordinated nodes share a MPR channel and assess its performance by designing additive-increase multiplicative-decrease MAC (AIMD-MAC) to achieve the max-min fairness. We show that with an appropriate set of parameters, AIMD-MAC can be applied to distributed environments where the number of nodes and channel capacity are not constant to achieve at least 90% of the performance of the benchmark. For multi-hop scenarios, we observe the M property of MPT/MPR networks, which profoundly changes the traditional understanding of managing a multi-hop wireless network. By identifying and investigating the M property, we propose novel algorithms to evaluate the MPT/MPR networks and demonstrate the relative importance of the MPT and MPR capacity limits. To efficiently manage the multi-hop flows traversing a MPT/MPR network, we design the AIMD backpressure MAC (AB-MAC) algorithm. Extensive simulations show that AB-MAC significantly outperforms IEEE 802.11 especially in dense networks.

Download or read book Analytical Modeling of Medium Access Control Protocols in Wireless Networks written by Marcelo Menezes Carvalho and published by . This book was released on 2006 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new modeling framework is introduced for the analytical study of medium access control (MAC) protocols operating in multihop wireless ad hoc networks, i.e., wireless networks characterized by the lack of any pre-existent infrastructure and where participating devices must cooperatively provide the basic functionalities that are common to any computer network. The proposed modeling framework focuses on the interactions between the physical (PHY) and MAC layers, and on the impact that each node has on the dynamics of every other node in the network. To account for the effects of both cross-layer interactions and the interference among all nodes, a novel linear model is introduced with which topology and PHY/MAC-layer aspects are naturally incorporated in what we define as interference matrices. A key feature of the model is that nodes can be modeled individually, i.e., it allows a per-node setup of many layer-specific parameters. Moreover, no spatial probability distribution or special arrangement of nodes is assumed; the model allows the computation of individual (per-node) performance metrics for any given network topology and radio channel model.

Download or read book Medium Access Control and Adaptive Transmission Techniques in Wireless Networks written by Alaa Hilal Essa Muqattash and published by . This book was released on 2005 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cross layer Optimization of Coded Wireless Networks written by Hulya Seferoglu and published by . This book was released on 2010 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: The network coding paradigm advocates that intermediate nodes should not only forward, but also process and combine packets, which has the potential to increase throughput and facilitate distributed operation of networks. This dissertation focuses on wireless networks, where network coding can be gracefully combined with and exploit the properties of the wireless networks. The goal is to design and evaluate algorithms and protocols, on top of given constructive network coding schemes, so as to fully exploit the network coding capabilities. The contributions of this dissertation are the joint optimization of (i) video streaming, (ii) rate control, and (iii) error correction, together with the underlying network coding mechanisms. We first study video streaming over coded wireless networks. Our key insight is that, when the transmitted flows are video, network codes should be selected so as to maximize not only the network throughput but also the video quality. We propose video-aware opportunistic network coding schemes that take into account the importance and deadlines of video packets. Second, we study rate control and scheduling. The key intuition is that network coding introduces network coded flows and new conflicts between nodes, which should be taken into account both in rate control and scheduling. We consider two types of traffic; video and TCP. In the case of video, its time-varying nature affects the underlying network coding opportunities. We observe that by delaying some scenes and by optimizing the rate allocation, we can create more network coding opportunities and thus improve video quality. In the case of TCP traffic, TCP flows do not fully exploit the network coding opportunities due to their bursty behavior and due to the fact that TCP is agnostic to network coding. In order to improve the performance of TCP flows over coded wireless networks, we propose a network-coding aware queue management scheme. In the last part of this thesis, we combine inter- and intra-session network coding (I2NC). Our scheme, I2NC provides resilience to loss thanks to the error-correcting capabilities of intra-session network coding. Furthermore, it allows intermediate nodes to operate without the knowledge of the decoding buffers at their neighbors.

Download or read book Medium Access Control MAC Protocol for Reconfigurable Wireless Networks written by Wiwat Ruengmee and published by . This book was released on 1997 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modulation and Coding written by Alister Burr and published by Prentice Hall PTR. This book was released on 2001 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preface. Abbreviations. 1. Introduction to modulation and coding. 2. Principles of linear modulation. 3. Modulation for non-linear systems. 4. Modem design. 5. Principles of FEC Coding. 6. Cyclic block codes. 7. Convolutionals codes. 8. Coded modulation. 9. Modulation and coding on multipath channels. 10. OFDM. 11. Turbo-codes. Appendix 1. Finite field theory. Appendix 2. The MAP algorithm.

Download or read book High Performance Medium Access Control Protocols for Decentralized Wireless Networks Using Local Coordination written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks differ from their wired counterparts in that communication between nodes takes place over a "link" using an RF, acoustic, optical, or other signal transmitted through the air or water instead of, as their name implies, a wire. This difference changes the frequency of transmission errors from extremely rare to almost constant, and introduces inter-node interference as a significant problem. Wireless networks are typically more limited than wired networks in terms of bandwidth, computational ability, power, and centralized management. Efficient handling of transmission errors and reducing interference are thus vital in maximizing network performance. This dissertation addresses two separate aspects of wireless networks with a common theme of low overhead, local coordination between nodes, and often using inferences or even informed guesses to make decisions. To address the problem of transmission errors, we study two medium access control (MAC) protocols that use minimal-overhead, local coordination schemes to allow cooperation between neighboring nodes: one with and one without a cooperation-enabled physical layer. To address the problem of interference, we study two closely related MAC protocols that use local coordination between neighboring nodes to build an interference-free transmission schedule, for (1) supporting latency-sensitive applications over long routes in mesh networks, and (2) increasing channel utilization and energy efficiency in underwater acoustic networks. Our first work focuses on mobile ad hoc networks where if any link in a route fails, multiple fruitless attempts are currently made by most of the existing MAC protocols to use the failed link before reporting failure to the routing layer and/or attempting local recovery. The high frequency of link errors between mobile nodes requires rapid recovery to provide acceptable performance. We design CIFLER, a cross-layer approach which uses enhanced channel reservation messages to allow alternate nodes to immediately elect themselves using only inferred neighbor information. This self-election avoids reliance on individual links, and uses diversity to minimize the impact frequent link errors have on delay, energy efficiency, and the functioning of upper layer protocols. We show via both analysis and simulation that CIFLER provides better performance in typical MANET scenarios. Unlike other local recovery schemes, CIFLER uses only a minor modification to IEEE 802.11 DCF, does not suffer from duplicated messages, allows neighboring nodes to almost immediately learn the information needed to assist in the recovery of existing routes, and does not require additional hardware, delays, or control messages. Our second work applies the same concept of inferred neighbor information to cooperative communications, where the signals of simultaneous transmissions by multiple nodes constructively combine in the wireless medium. Studies on the physical layer capabilities (via either information theory or numerical analysis) have shown the significant performance improvements of cooperative communications. However, these studies ignore both the overheads incurred in real implementations of the cooperative techniques at the physical layer and their interactions with higher layer protocols in a networking context. We implement a path-centric MAC protocol that uses minimal control messages to reserve a multi-hop path between source and destination nodes, and perform coordination between relay nodes. We then realistically study the performance of cooperation in networking scenarios by taking into account overheads incurred at the physical, MAC, and network layers. Simulations demonstrate that significant performance improvement can be achieved by employing cooperation. We also demonstrate the overheads which challenge the effectiveness of such schemes in real networks. Our third work deals with the issue of interference and transmission scheduling in mesh networks, where links are generally reliable if no interference is present. In current wireless networks, access to the shared wireless medium is controlled via either a TDMA- or a CSMA-based scheme. While usable in single-hop networks, these techniques are often far from optimal, and result in significant per-hop and per-packet delay and jitter, making multi-hop wireless mesh networks a particularly harsh environment for real-time, isochronous applications such as VoIP. We present a new time-based MAC protocol, FLASHR, for wireless mesh networks carrying delay-sensitive isochronous traffic. In our scheme, nodes use simple local coordination mechanisms to form adaptive transmission schedules which attain the desired quality of service. Simulations show that our scheme achieves near-optimal capacity, minimal jitter, and a weaker correlation between route length and end-to-end delay. Our final work adapts the FLASHR MAC protocol for use in underwater acoustic networks. A time-based MAC has potential advantages over FDMA and CDMA approaches in terms of hardware simplicity, energy efficiency, and delay. Unfortunately, the channel utilization of existing TDMA and CSMA acoustic MAC protocols is generally low due to the long propagation delays of acoustic signals. We argue that several ideas taken from RF protocols, including exclusive channel access, are either unnecessary in acoustic networks or must be redefined. We design UW-FLASHR, a modification to FLASHR which uses additional local control messages to create a time-based MAC protocol for acoustic networks which does not require centralized control, tight clock synchronization, or accurate propagation delay estimation. Our results show that UWFLASHR achieves higher channel utilization than the maximum utilization possible with existing time-based exclusive-access MAC protocols, particularly when the ratio of propagation delay to transmission delay is high, or data payloads are small.

Download or read book Channel Adaptive Real time Medium Access Control Protocols for Industrial Wireless Networks written by Kavitha Balasubramanian and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Medium Access Control Protocol with Reliable Multicast Support for Wireless Networks written by Vikram Shankar and published by . This book was released on 2002 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Modulation and Coding based Packet Scheduling with Inter base Station Coordination in Fixed Cellular Broadband Wireless Networks microform written by Md. Mahmudur Rahman and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Joint Adaptive Modulation and Channel Coding for Wireless Multimedia Communications written by Rimas Adnan Zrae and published by . This book was released on 2011 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this thesis, we outline a new approach to tackle the problem of reliable image and video transmission over wireless channels. We propose an adaptive transmission scheme that attempts to meet the available channel conditions through the adaptation of the modulation modes and channel coding rates."--P. iii-iv.

Download or read book Design and Performance Optimization of Wireless Network Coding for Delay Sensitive Applications written by Mohammad Esmaeilzadeh Fereydani and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, network coding (NC) has emerged as a new paradigm for data communications and has attracted much popularity and research interest in information and coding theory, networking, wireless communications and data storage. Random linear NC (RLNC) is a subclass of NC that has shown to be suitable for a wide range of applications thanks to its desirable properties, namely throughput-optimality, simple encoder design and efficient operation with minimum feedback requirements. However, for delay-sensitive applications, the mentioned advantages come with two main issues that may restrict RLNC usage in practice. First is the trade-off between the delay and throughput performances of RLNC, which can adversely affect the throughput-optimality of RLNC and hence the overall performance of RLNC. Second is the usage of feedback, where even if feedback is kept at minimum it can still incur large amount of delay and thus degrade the RLNC performance, if not optimized properly. In this thesis, we aim to investigate these issues under two broad headings: RLNC for applications over time division duplexing (TDD) channels and RLNC for layered video streaming. For the first class of problems, we start with the reliable broadcast communication over TDD wireless channels with memory, in the presence of large latency. Considering TDD channels with large latency, excessive use of feedback could be costly. Therefore, joint optimization of feedback rate and RLNC parameters has been studied previously for memoryless channels to minimize the average transmission time for such settings. Here, we extend the methodology to the case of channels with memory by benefiting from a Gilbert-Elliot channel model. It is demonstrated that significant improvement in the performance could be achieved compared to the scheme which is oblivious to the temporal correlations in the erasure channels. Then, keeping our focus on network coded TDD broadcast systems with large latency, we consider delay sensitive applications and study the issue of throughput and packet drop rate (PDR) optimization as two performance metrics when the transmission time is considered fixed. We propose a systematic framework to investigate the advantage of using feedback by comparing feedback-free and feedback schemes. Furthermore, the complicated interplay of the mean throughputs and PDRs of users with different packet erasure conditions is discussed. Then, to better analyze the throughput performance of the proposed feedback-free scheme, we formulate the probability and cumulative density functions of users' throughputs and utilize them to investigate the problem of guaranteeing the quality of service. Finally, it is shown that the optimized feedback-free RLNC broadcast scheme works close enough to an idealistic RLNC scheme, where an omniscient sender is assumed to know the reception status of all users immediately after each transmission. For the second class of problems, we consider transmitting layered video streams over heterogeneous single-hop wireless networks using feedback-free RLNC. For the case of broadcasting single video stream, we combine RLNC with unequal error protection and our main purpose is twofold. First, to systematically investigate the benefits of the layered approach in servicing users with different reception capabilities. Second, to study the effect of not using feedback, by comparing feedback-free schemes with idealistic full-feedback schemes. To this end, we consider a content-independent performance metric and propose a general framework for calculation of this metric, which can highlight the effect of key parameters of the system, video and channel. We study the effect of number of layers and propose a scheme that selects the optimum number of layers adaptively to achieve the highest performance. Assessing the proposed schemes with real H.264 test streams, the trade-offs among the users' performances are discussed and the gain of adaptive selection of number of layers to improve the trade-offs is shown. Furthermore, it is observed that the performance gap between the proposed feedback-free scheme and the idealistic scheme is small and the adaptive selection of number of video layers further closes the gap. Finally, we extend the problem of layered video streaming to the case of transmitting multiple independent layered video streams and demonstrate the gain of coding across streams (i.e., inter-session RLNC) over coding only within streams (i.e., intra-session RLNC).