222 research outputs found
Quality of service differentiation for multimedia delivery in wireless LANs
Delivering multimedia content to heterogeneous devices over a variable networking environment while maintaining high quality levels involves many technical challenges. The research reported in this thesis presents a solution for Quality of Service (QoS)-based service differentiation when delivering multimedia content over the wireless LANs. This thesis has three major contributions outlined below:
1. A Model-based Bandwidth Estimation algorithm (MBE), which estimates the available bandwidth based on novel TCP and UDP throughput models over IEEE 802.11 WLANs. MBE has been modelled, implemented, and tested through simulations and real life testing. In comparison with other bandwidth estimation techniques, MBE shows better performance in terms of error rate, overhead, and loss.
2. An intelligent Prioritized Adaptive Scheme (iPAS), which provides QoS service differentiation for multimedia delivery in wireless networks. iPAS assigns dynamic priorities to various streams and determines their bandwidth share by employing a probabilistic approach-which makes use of stereotypes. The total bandwidth to be allocated is estimated using MBE. The priority level of individual stream is variable and dependent on stream-related characteristics and delivery QoS parameters. iPAS can be deployed seamlessly over the original IEEE 802.11 protocols and can be included in the IEEE 802.21 framework in order to optimize the control signal communication. iPAS has been modelled, implemented, and evaluated via simulations. The results demonstrate that iPAS achieves better performance than the equal channel access mechanism over IEEE 802.11 DCF and a service differentiation scheme on top of IEEE 802.11e EDCA, in terms of fairness, throughput, delay, loss, and estimated PSNR. Additionally, both objective and subjective video quality assessment have been performed using a prototype system.
3. A QoS-based Downlink/Uplink Fairness Scheme, which uses the stereotypes-based structure to balance the QoS parameters (i.e. throughput, delay, and loss) between downlink and uplink VoIP traffic. The proposed scheme has been modelled and tested through simulations. The results show that, in comparison with other downlink/uplink fairness-oriented solutions, the proposed scheme performs better in terms of VoIP capacity and fairness level between downlink and uplink traffic
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 componentâs 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
Resource allocation for multimedia messaging services over EGPRS
The General Packet Radio Service (GPRS) is a new bearer service for GSM that greatly simplifies wireless access to packet data networks, such as the Internet, corporate LANs or to mobile portals. It applies a packet radio standard to transfer user data packets in wellorganized way between Mobile Stations (MS) and external packet data networks. The Enhanced General Packet Radio Service (EGPRS) is an extension of GPRS, offering much greater capacity. These enhancements have allowed the introduction of new services like Multimedia Messaging Services (MMS). MMS enables messaging with full content versatility, including images, audio, video, data and text, from terminal to terminal or from terminal to e-mail.
The Wireless Application Protocol (WAP) is the WAP Forum standard for the presentation and delivery of wireless information and telephony services on mobile phones and other wireless terminals.
In this thesis it is indicated that efficient radio resource allocation is necessary for managing different types of traffic in order to maintain the quality demands for different types of services. A theoretical model of MMS and WAP traffic is developed, and based on this model a simulator is implemented in Java programming language.
This thesis proposes two techniques to improve the radio resource allocation algorithm performance called "radio link condition diversification" and "interactive traffic class prioritization". The radio link condition diversification technique defines minimum radio link quality that allows the user to receive their packets. The interactive traffic class prioritization technique defines different priorities for WAP packets and for MMS packets. Both techniques give good results in increasing user's perception of services and increasing network efficiency.
This thesis indicates also that the prioritization mechanism successfully improves the response time of the interactive service by up to 80% with a setting of priority for interactive traffic class and decreasing the performance of the background traffic. This decrease is within a range acceptable by the end-user and that the link conditions limit mechanism has an advantage in terms of resource utilization
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
Distributed Implementation of eXtended Reality Technologies over 5G Networks
MenciĂłn Internacional en el tĂtulo de doctorThe revolution of Extended Reality (XR) has already started and is rapidly
expanding as technology advances. Announcements such as Metaâs Metaverse have
boosted the general interest in XR technologies, producing novel use cases. With
the advent of the fifth generation of cellular networks (5G), XR technologies are
expected to improve significantly by offloading heavy computational processes from
the XR Head Mounted Display (HMD) to an edge server. XR offloading can rapidly
boost XR technologies by considerably reducing the burden on the XR hardware,
while improving the overall user experience by enabling smoother graphics and more
realistic interactions. Overall, the combination of XR and 5G has the potential to
revolutionize the way we interact with technology and experience the world around
us.
However, XR offloading is a complex task that requires state-of-the-art tools
and solutions, as well as an advanced wireless network that can meet the demanding
throughput, latency, and reliability requirements of XR. The definition of these
requirements strongly depends on the use case and particular XR offloading implementations.
Therefore, it is crucial to perform a thorough Key Performance
Indicators (KPIs) analysis to ensure a successful design of any XR offloading solution.
Additionally, distributed XR implementations can be intrincated systems with
multiple processes running on different devices or virtual instances. All these agents
must be well-handled and synchronized to achieve XR real-time requirements and
ensure the expected user experience, guaranteeing a low processing overhead. XR
offloading requires a carefully designed architecture which complies with the required
KPIs while efficiently synchronizing and handling multiple heterogeneous devices.
Offloading XR has become an essential use case for 5G and beyond 5G technologies.
However, testing distributed XR implementations requires access to advanced
5G deployments that are often unavailable to most XR application developers. Conversely,
the development of 5G technologies requires constant feedback from potential
applications and use cases. Unfortunately, most 5G providers, engineers, or
researchers lack access to cutting-edge XR hardware or applications, which can hinder
the fast implementation and improvement of 5Gâs most advanced features. Both
technology fields require ongoing input and continuous development from each other
to fully realize their potential. As a result, XR and 5G researchers and developers
must have access to the necessary tools and knowledge to ensure the rapid and
satisfactory development of both technology fields.
In this thesis, we focus on these challenges providing knowledge, tools and solutiond towards the implementation of advanced offloading technologies, opening the
door to more immersive, comfortable and accessible XR technologies. Our contributions
to the field of XR offloading include a detailed study and description of the
necessary network throughput and latency KPIs for XR offloading, an architecture
for low latency XR offloading and our full end to end XR offloading implementation
ready for a commercial XR HMD. Besides, we also present a set of tools which can
facilitate the joint development of 5G networks and XR offloading technologies: our
5G RAN real-time emulator and a multi-scenario XR IP traffic dataset.
Firstly, in this thesis, we thoroughly examine and explain the KPIs that are
required to achieve the expected Quality of Experience (QoE) and enhanced immersiveness
in XR offloading solutions. Our analysis focuses on individual XR
algorithms, rather than potential use cases. Additionally, we provide an initial
description of feasible 5G deployments that could fulfill some of the proposed KPIs
for different offloading scenarios.
We also present our low latency muti-modal XR offloading architecture, which
has already been tested on a commercial XR device and advanced 5G deployments,
such as millimeter-wave (mmW) technologies. Besides, we describe our full endto-
end complex XR offloading system which relies on our offloading architecture to
provide low latency communication between a commercial XR device and a server
running a Machine Learning (ML) algorithm. To the best of our knowledge, this is
one of the first successful XR offloading implementations for complex ML algorithms
in a commercial device.
With the goal of providing XR developers and researchers access to complex
5G deployments and accelerating the development of future XR technologies, we
present FikoRE, our 5G RAN real-time emulator. FikoRE has been specifically
designed not only to model the network with sufficient accuracy but also to support
the emulation of a massive number of users and actual IP throughput. As FikoRE
can handle actual IP traffic above 1 Gbps, it can directly be used to test distributed
XR solutions. As we describe in the thesis, its emulation capabilities make FikoRE
a potential candidate to become a reference testbed for distributed XR developers
and researchers.
Finally, we used our XR offloading tools to generate an XR IP traffic dataset
which can accelerate the development of 5G technologies by providing a straightforward
manner for testing novel 5G solutions using realistic XR data. This dataset is
generated for two relevant XR offloading scenarios: split rendering, in which the rendering
step is moved to an edge server, and heavy ML algorithm offloading. Besides,
we derive the corresponding IP traffic models from the captured data, which can be
used to generate realistic XR IP traffic. We also present the validation experiments
performed on the derived models and their results.This work has received funding from the European Union (EU) Horizon 2020 research and innovation programme under the Marie SkĆodowska-Curie ETN TeamUp5G, grant agreement No. 813391.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Narciso GarcĂa Santos.- Secretario: Fernando DĂaz de MarĂa.- Vocal: Aryan Kaushi
An intelligent radio access network selection and optimisation system in heterogeneous communication environments
PhDThe overlapping of the different wireless network technologies creates heterogeneous communication environments. Future mobile communication system considers the technological and operational services of heterogeneous communication environments. Based on its packet switched core, the access to future mobile communication system will not be restricted to the mobile cellular networks but may be via other wireless or even wired technologies. Such universal access can enable service convergence, joint resource management, and adaptive quality of service. However, in order to realise the universal access, there are still many pending challenges to solve. One of them is the selection of the most appropriate radio access network.
Previous work on the network selection has concentrated on serving the requesting user, but the existing users and the consumption of the network resources were not the main focus. Such network selection decision might only be able to benefit a limited number of users while the satisfaction levels of some users are compromised, and the network resources might be consumed in an ineffective way. Solutions are needed to handle the radio access network selection in a manner that both of the satisfaction levels of all users and the network resource consumption are considered.
This thesis proposes an intelligent radio access network selection and optimisation system. The work in this thesis includes the proposal of an architecture for the radio access network selection and optimisation system and the creation of novel adaptive algorithms that are employed by the network selection system. The proposed algorithms solve the limitations of previous work and adaptively optimise network resource consumption and implement different policies to cope with different scenarios, network conditions, and aims of operators. Furthermore, this thesis also presents novel network resource availability evaluation models. The proposed models study the physical principles of the considered radio access network and avoid employing assumptions which are too stringent abstractions of real network scenarios. They enable the implementation of call level simulations for the comparison and evaluation of the performance of the network selection and optimisation algorithms
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