Traffic placement policies for a multi-band network

Recently protocols were introduced that enable the integration of synchronous traffic (voice or video) and asynchronous traffic (data) and extend the size of local area networks without loss in speed or capacity. One of these is DRAMA, a multiband protocol based on broadband technology. It provides dynamic allocation of bandwidth among clusters of nodes in the total network. A number of traffic placement policies for such networks are proposed and evaluated. Metrics used for performance evaluation include average network access delay, degree of fairness of access among the nodes, and network throughput. The feasibility of the DRAMA protocol is established through simulation studies. DRAMA provides effective integration of synchronous and asychronous traffic due to its ability to separate traffic types. Under the suggested traffic placement policies, the DRAMA protocol is shown to handle diverse loads, mixes of traffic types, and numbers of nodes, as well as modifications to the network structure and momentary traffic overloads

Extremely high data-rate, reliable network systems research

Significant progress was made over the year in the four focus areas of this research group: gigabit protocols, extensions of metropolitan protocols, parallel protocols, and distributed simulations. Two activities, a network management tool and the Carrier Sensed Multiple Access Collision Detection (CSMA/CD) protocol, have developed to the point that a patent is being applied for in the next year; a tool set for distributed simulation using the language SIMSCRIPT also has commercial potential and is to be further refined. The year's results for each of these areas are summarized and next year's activities are described

A study of QoS support for real time multimedia communication over IEEE802.11 WLAN : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Computer Systems Engineering, Massey University, Albany, New Zealand

Quality of Service (QoS) is becoming a key problem for Real Time (RT) traffic transmitted over Wireless Local Area Network (WLAN). In this project the recent proposals for enhanced QoS performance for RT multimedia is evaluated and analyzed. Two simulation models for EDCF and HCF protocols are explored using OPNET and NS-2 simulation packages respectively. From the results of the simulation, we have studied the limitations of the 802.1 le standard for RT multimedia communication and analysed the reasons of the limitations happened and proposed the solutions for improvement. Since RT multimedia communication encompasses time-sensitive traffic, the measure of quality of service generally is minimal delay (latency) and delay variation (jitter). 802.11 WLAN standard focuses on the PHY layer and the MAC layer. The transmitted data rate on PHY layer are increased on standards 802.1 lb, a, g, j, n by different code mapping technologies while 802.1 le is developed specially for the QoS performance of RT-traffics at the MAC layer. Enhancing the MAC layer protocols are the significant topic for guaranteeing the QoS performance of RT-traffics. The original MAC protocols of 802.11 are DCF (Distributed Coordination Function) and PCF (Point Coordinator Function). They cannot achieve the required QoS performance for the RT-traffic transmission. IEEE802.lle draft has developed EDCF and HCF instead. Simulation results of EDCF and HCF models that we explored by OPNET and NS-2, show that minimal latency and jitter can be achieved. However, the limitations of EDCF and HCF are identified from the simulation results. EDCF is not stable under the high network loading. The channel utilization is low by both protocols. Furthermore, the fairness index is very poor by the HCF. It means the low priority traffic should starve in the WLAN network. All these limitations are due to the priority mechanism of the protocols. We propose a future work to develop dynamic self-adaptive 802.11c protocol as practical research directions. Because of the uncertainly in the EDCF in the heavy loading, we can add some parameters to the traffic loading and channel condition efficiently. We provide indications for adding some parameters to increase the EDCF performance and channel utilization. Because all the limitations are due to the priority mechanism, the other direction is doing away with the priority rule for reasonable bandwidth allocation. We have established that the channel utilization can be increased and collision time can be reduced for RT-traffics over the EDCF protocol. These parameters can include loading rate, collision rate and total throughput saturation. Further simulation should look for optimum values for the parameters. Because of the huge polling-induced overheads, HCF has the unsatisfied tradeoff. This leads to poor fairness and poor throughput. By developing enhanced HCF it may be possible to enhance the RI polling interval and TXOP allocation mechanism to get better fairness index and channel utilization. From the simulation, we noticed that the traffics deployment could affect the total QoS performance, an indication to explore whether the classification of traffics deployments to different categories is a good idea. With different load-based traffic categories, QoS may be enhanced by appropriate bandwidth allocation Strategy

The Feasibility of ATM operations over high frequency radio and the viability of the ATM/HF architecture

High Frequency (HF) radio is still a vital part of communications networks because its low cost and long distance capabilities, and still plays important roles as primary, supplemental, or redundant backup systems. Asynchronous Transfer Mode (ATM) is increasingly becoming an important part of communications, especially with LAN Emulation (LANE) specifications. Add to this the importance and increasing interest and dependency upon wireless networking, and it becomes inevitable that research into mobile ATM networking over HF radio would be considered. To test the feasibility of ATM networking over HF radio it was decided that a simulation would be developed to collect some basic information on call blocking and throughput. In order to build the simulation it was necessary to have an architectural framework of a mobile ATM network operating over HF radio. ATM/HF (ATM over HF) is the proposed architecture. ATM/HF is a proposed architecture that provides for networking mobile ATM nodes such as ships, planes, and trucks, over HF radio. It is based upon a recommended 64 kHz bandwidth which allows for a 128 kbps data rate. The ATM/HF architecture utilizes three different Media Access Control (MAC) protocols for network startup and access from the various network states, and incorporates several recently proposed dynamic capabilities for control of bandwidth and the integration of voice, data, and video. The proposal provides frame and wireless ATM (WATM) packet structures and a reference model for flow of the cells from the ATM Adaptation Layer (AAL) through the radio. An important feature is the use of channels, called channelization, to increase both network capacity and distance. The simulation was built to represent an active network state with active nodes connecting and disconnecting calls in a dynamic way with explicit connection messages. The purpose of starting from this network state was to measure the call blocking and throughput of a single channel. Two user types were developed, one to represent telephone voice and the other to represent computer data traffic. By varying the number of users per node and by type, the level of call blocking and throughput could be changed. Graphing the levels it could be determined the maximum capacity a single channel could support and thus determine if ATM over HF radio is feasible. In addition, the same information was used to determine the viability of the ATM/HF architecture. Although the simulation did not incorporate all the dynamic features of the recommended protocols, it does dynamically assign slots, rearrange slots to utilize non-contiguous available slots, and adjust the data rate of computer connections to accommodate voice call requests. This was done to reduce the level of voice call blocking which became the determining factor in deciding feasibility. It was determined that mobile ATM networking over HF radio is possible since the voice call blocking of a single channel was at the 10% level, overall call blocking was at the 6% level, and throughput was at the 53% level. It was determined that a single channel could support six voice and a minimum of ten data users. Although throughput, which is defined as the number of available slot used, was lower than expected, the possibility exists for utilizing the unused slots by incorporating additional dynamic capabilities that would increase the number of users supportable by a single channel. Throughput can be also be increased by incorporating Available Bit Rate (ABR) and Unspecified Bit Rate (UBR) traffic. The call blocking and throughput levels prove that ATM/HF is a viable method for supporting ATM operations. Although the call blocking level achieved the voice call blocking level and exceeding the overall call blocking level, the throughput level shows that there is a lot of wasted bandwidth. Further study of the design is required to improve the throughput level. Further development of the simulation is required in order to test the MAC protocols and to test the effects of the Bit Error Rate and fading effects of HF radio. The final conclusion, however, is that ATM over HF radio is feasible, that ATM/HF is a viable architecture, and that further research should be conducted into both

Medium Access Control Layer Implementation on Field Programmable Gate Array Board for Wireless Networks

Triple play services are playing an important role in modern telecommunications systems. Nowadays, more researchers are engaged in investigating the most efficient approaches to integrate these services at a reduced level of operation costs. Field Programmable Gate Array (FPGA) boards have been found as the most suitable platform to test new protocols as they offer high levels of flexibility and customization. This thesis focuses on implementing a framework for the Triple Play Time Division Multiple Access (TP-TDMA) protocol using the Xilinx FPGA Virtex-5 board. This flexible framework design offers network systems engineers a reconfigiirable platform for triple-play systems development. In this work, MicorBlaze is used to perform memory and connectivity tests aiming to ensure the establishment of the connectivity as well as board’s processor stability. Two different approaches are followed to achieve TP-TDMA implementa­tion: systematic and conceptual. In the systematic approach, a bottom-to-top design is chosen where four subsystems are built with various components. Each component is then tested individually to investigate its response. On the other hand, the concep­tual approach is designed with only two components, in which one of them is created with the help of Xilinx Integrated Software Environment (ISE) Core Generator. The system is integrated and then tested to check its overall response. In summary, the work of this thesis is divided into three sections. The first section presents a testing method for Virtex-5 board using MicroBlaze soft processor. The following two sections concentrate on implementing the TP-TDMA protocol on the board by using two design approaches: one based on designing each component from scratch, while the other one focuses more on the system’s broader picture

Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

Performance Improvements for FDDI and CSMA/CD Protocols

The High-Performance Computing Initiative from the White House Office of Science and Technology Policy has defined 20 major challenges in science and engineering which are dependent on the solutions to a number of high-performance computing problems. One of the major areas of focus of this initiative is the development of gigabit rate networks to be used in environments such as the space station or a National Research and Educational Network (NREN). The strategy here is to use existing network designs as building blocks for achieving higher rates, with the ultimate goal being a gigabit rate network. Two strategies which contribute to achieving this goal are examined in detail.1 FDDI2 is a token ring network based on fiber optics capable of a 100 Mbps rate. Both media access (MAC) and physical layer modifications are considered. A method is presented which allows one to determine maximum utilization based on the token-holding timer settings. Simulation results show that employing the second counter-rotating ring in combination with destination removal has a multiplicative effect greater than the effect which either of the factors have individually on performance. Two 100 Mbps rings can handle loads in the range of 400 to 500 Mbps for traffic with a uniform distribution and fixed packet size. Performance is dependent on the number of nodes, improving as the number increases. A wide range of environments are examined to illustrate robustness, and a method of implementation is discussed

Thirty Years of Machine Learning: The Road to Pareto-Optimal Wireless Networks

Future wireless networks have a substantial potential in terms of supporting a broad range of complex compelling applications both in military and civilian fields, where the users are able to enjoy high-rate, low-latency, low-cost and reliable information services. Achieving this ambitious goal requires new radio techniques for adaptive learning and intelligent decision making because of the complex heterogeneous nature of the network structures and wireless services. Machine learning (ML) algorithms have great success in supporting big data analytics, efficient parameter estimation and interactive decision making. Hence, in this article, we review the thirty-year history of ML by elaborating on supervised learning, unsupervised learning, reinforcement learning and deep learning. Furthermore, we investigate their employment in the compelling applications of wireless networks, including heterogeneous networks (HetNets), cognitive radios (CR), Internet of things (IoT), machine to machine networks (M2M), and so on. This article aims for assisting the readers in clarifying the motivation and methodology of the various ML algorithms, so as to invoke them for hitherto unexplored services as well as scenarios of future wireless networks.Comment: 46 pages, 22 fig