341 research outputs found
An improved medium access control protocol for real-time applications in WLANs and its firmware development
The IEEE 802.11 Wireless Local Area Network (WLAN), commonly known as Wi-Fi, has emerged as a popular internet access technology and researchers are continuously working on improvement of the quality of service (QoS) in WLAN by proposing new and efficient schemes. Voice and video over Internet Protocol (VVoIP) applications are becoming very popular in Wi-Fi enabled portable/handheld devices because of recent technological advancements and lower service costs. Different from normal voice and video streaming, these applications demand symmetric throughput for the upstream and downstream. Existing Wi-Fi standards are optimised for generic internet applications and fail to provide symmetric throughput due to traffic bottleneck at access points. Performance analysis and benchmarking is an integral part of WLAN research, and in the majority of the cases, this is done through computer simulation using popular network simulators such as Network Simulator ff 2 (NS-2) or OPNET. While computer simulation is an excellent approach for saving time and money, results generated from computer simulations do not always match practical observations. This is why, for proper assessment of the merits of a proposed system in WLAN, a trial on a practical hardware platform is highly recommended and is often a requirement. In this thesis work, with a view to address the abovementioned challenges for facilitating VoIP and VVoIP services over Wi-Fi, two key contributions are made: i) formulating a suitable medium access control (MAC) protocol to address symmetric traffic scenario and ii) firmware development of this newly devised MAC protocol for real WLAN hardware. The proposed solution shows signifocant improvements over existing standards by supporting higher number of stations with strict QoS criteria. The proposed hardware platform is available off-the-shelf in the market and is a cost effective way of generating and evaluating performance results on a hardware system
LTE Optimization and Resource Management in Wireless Heterogeneous Networks
Mobile communication technology is evolving with a great pace. The development of the Long Term Evolution (LTE) mobile system by 3GPP is one of the milestones in this direction. This work highlights a few areas in the LTE radio access network where the proposed innovative mechanisms can substantially improve overall LTE system performance. In order to further extend the capacity of LTE networks, an integration with the non-3GPP networks (e.g., WLAN, WiMAX etc.) is also proposed in this work. Moreover, it is discussed how bandwidth resources should be managed in such heterogeneous networks. The work has purposed a comprehensive system architecture as an overlay of the 3GPP defined SAE architecture, effective resource management mechanisms as well as a Linear Programming based analytical solution for the optimal network resource allocation problem. In addition, alternative computationally efficient heuristic based algorithms have also been designed to achieve near-optimal performance
Final report on the evaluation of RRM/CRRM algorithms
Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin
Quality of service optimization of multimedia traffic in mobile networks
Mobile communication systems have continued to evolve beyond the currently deployed Third
Generation (3G) systems with the main goal of providing higher capacity. Systems beyond 3G
are expected to cater for a wide variety of services such as speech, data, image transmission,
video, as well as multimedia services consisting of a combination of these. With the air interface
being the bottleneck in mobile networks, recent enhancing technologies such as the High Speed
Downlink Packet Access (HSDPA), incorporate major changes to the radio access segment of
3G Universal Mobile Telecommunications System (UMTS). HSDPA introduces new features
such as fast link adaptation mechanisms, fast packet scheduling, and physical layer retransmissions
in the base stations, necessitating buffering of data at the air interface which presents a
bottleneck to end-to-end communication. Hence, in order to provide end-to-end Quality of
Service (QoS) guarantees to multimedia services in wireless networks such as HSDPA, efficient
buffer management schemes are required at the air interface.
The main objective of this thesis is to propose and evaluate solutions that will address the
QoS optimization of multimedia traffic at the radio link interface of HSDPA systems. In the
thesis, a novel queuing system known as the Time-Space Priority (TSP) scheme is proposed for
multimedia traffic QoS control. TSP provides customized preferential treatment to the constituent
flows in the multimedia traffic to suit their diverse QoS requirements. With TSP queuing, the
real-time component of the multimedia traffic, being delay sensitive and loss tolerant, is given
transmission priority; while the non-real-time component, being loss sensitive and delay tolerant,
enjoys space priority. Hence, based on the TSP queuing paradigm, new buffer managementalgorithms are designed for joint QoS control of the diverse components in a multimedia session
of the same HSDPA user. In the thesis, a TSP based buffer management algorithm known as the
Enhanced Time Space Priority (E-TSP) is proposed for HSDPA. E-TSP incorporates flow
control mechanisms to mitigate congestion in the air interface buffer of a user with multimedia
session comprising real-time and non-real-time flows. Thus, E-TSP is designed to provide
efficient network and radio resource utilization to improve end-to-end multimedia traffic
performance. In order to allow real-time optimization of the QoS control between the real-time
and non-real-time flows of the HSDPA multimedia session, another TSP based buffer management
algorithm known as the Dynamic Time Space Priority (D-TSP) is proposed. D-TSP
incorporates dynamic priority switching between the real-time and non-real-time flows. D-TSP
is designed to allow optimum QoS trade-off between the flows whilst still guaranteeing the
stringent real-time component’s QoS requirements. The thesis presents results of extensive
performance studies undertaken via analytical modelling and dynamic network-level HSDPA
simulations demonstrating the effectiveness of the proposed TSP queuing system and the TSP
based buffer management schemes
Service oriented networking for multimedia applications in broadband wireless networks
Extensive efforts have been focused on deploying broadband wireless networks. Providing mobile users with high speed network connectivity will let them run various multimedia applications on their wireless devices. In order to successfully deploy and operate broadband wireless networks, it is crucial to design efficient methods for supporting various services and applications in broadband wireless networks. Moreover, the existing access-oriented networking solutions are not able to fully address all the issues of supporting various applications with different quality of service requirements. Thus, service-oriented networking has been recently proposed and has gained much attention.
This dissertation discusses the challenges and possible solutions for supporting multimedia applications in broadband wireless networks. The service requirements of different multimedia applications such as video streaming and Voice over IP (VoIP) are studied and some novel service-oriented networking solutions for supporting these applications in broadband wireless networks are proposed. The performance of these solutions is examined in WiMAX networks which are the promising technology for broadband wireless access in the near future. WiMAX networks are based on the IEEE 802.16 standards which have defined different Quality of Service (QoS) classes to support a broad range of applications with varying service requirements to mobile and stationary users.
The growth of multimedia traffic that requires special quality of service from the network will impose new constraints on network designers who should wisely allocate the limited resources to users based on their required quality of service. An efficient resource management and network design depends upon gaining accurate information about the traffic profile of user applications. In this dissertation, the access level traffic profile of VoIP applications are studied first, and then a realistic distribution model for VoIP traffic is proposed. Based on this model, an algorithm to allocate resources for VoIP applications in WiMAX networks is investigated. Later, the challenges and possible solutions for transmitting MPEG video streams in wireless networks are discussed. The MPEG traffic model adopted by the WiMAX Forum is introduced and different application-oriented solutions for enhancing the performance of wireless networks with respect to MPEG video streaming applications are explained. An analytical framework to verify the performance of the proposed solutions is discoursed, and it is shown that the proposed solutions will improve the efficiency of VoIP applications and the quality of streaming applications over wireless networks. Finally, conclusions are drawn and future works are discussed
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