393 research outputs found
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
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
3G Wideband CDMA : packet-based optimisation for high data-rate downlink transmission
A third generation (3G) of mobile communication systems, based on Wideband CDMA, are intended to offer high-speed packet-based services. Network operators wish to maximise the throughput in the downlink of3G systems, which requires efficient allocation ofresources. This thesis considers the problem ofmaximising throughput in an interference dominated channel. Cooperative broadcasting is a theoretical technique to mitigate this problem. Its implementation in practical systems requires efficient resource allocati.on to maximise the thr(oughput whilst meeting system and user-imposed constramts. A resource allocation approach is presented for implementing cooperative broadcasting. Users are paired and a teclmique for allocating resources between the pair is developed. Then, a method for pairing the users is considered. Simulation results are presented, which show a throughput improvement over existing resource allocation approaches. The problem ofcontrolling the distribution ofrandomly arriving data to meet the resource allocation specifications is examined. A single-threshold buffer is proposed, which requires fewer calculations than an existing double-threshold buffer. Simulation results are presented which show a throughput improvement may be realised, greater than that which would achievable using other rate control schemes. Cooperative broadcasting may lead to transmissions to some users being allocated low power. When full channel infonnation is available at the transmitter, a water filling solution may be used to maximise capacity. However, when combined with buffer management, erasure may result. This erasure may be overcome using an erasure protection code. Such a code is examined. When combined with Turbo coding, ajoint detector may be used for providing error and erasure protection. Analysis ofthis detector shows a lower limit on the error rate, dependent on the probability of erasure. Simulation results show that using this approach the error rate is significantly improved. This code can then be used to increase capacity, whilst achieving low error rates.Imperial Users onl
The new enhancement of UMTS: HSDPA and HSUPA
During the last two decades, the world of the mobile communications grew a lot, as a
consequence of the increasing necessity of people to communicate. Now, the mobile
communications still need to improve for satisfies the user demands.
The new enhancement of UMTS in concrete HSDPA and HSUPA is one of these
improvements that the society needs. HSDPA and HSUPA which together are called
HSPA, give to the users higher data rates in downlink and uplink. The higher data rates
permit to the operators give more different types of services and at the same time with
better quality. As a result, people can do several new applications with their mobile
terminals like applications that before a computer and internet connection were
required, now it is possible to do directly with the mobile terminal.
This thesis consists in study these new technologies denominated HSDPA and HSUPA
and thus know better the last tendencies in the mobile communications. Also it has a
roughly idea about the future tendencies
Multiradio Resource Management: Parallel Transmission for Higher Throughput?
Mobile communication systems beyond the third generation will see the interconnection of heterogeneous radio access networks (UMTS, WiMax, wireless local area networks, etc.) in order to always provide the best quality of service (QoS) to users with multimode terminals. This scenario poses a number of critical issues, which have to be faced in order to get the best from the integrated access network. In this paper, we will investigate the issue of parallel transmission over multiple radio access technologies (RATs), focusing the attention on the QoS perceived by final users. We will show that the achievement of a real benefit from parallel transmission over multiple RATs is conditioned to the fulfilment of some requirements related to the kind of RATs, the multiradio resource management (MRRM) strategy, and the transport-level protocol behaviour. All these aspects will be carefully considered in our investigation, which will be carried out partly adopting an analytical approach and partly by means of simulations. In this paper, in particular, we will propose a simple but effective MRRM algorithm, whose performance will be investigated in IEEE802.11a-UMTS and IEEE802.11a-IEEE802.16e heterogeneous networks (adopted as case studies)
Dynamic Buffer Management for Multimedia QoS in Beyond 3G Wireless Networks
This paper investigates a dynamic buffer management scheme for QoS control of multimedia services in beyond 3G wireless systems. The scheme is studied in the context of the state-of-the-art 3.5G system i.e. the High Speed Downlink Packet Access (HSDPA) which enhances 3G UMTS to support high-speed packet switched services. Unlike earlier systems, UMTS-evolved systems from HSDPA and beyond incorporate mechanisms such as packet scheduling and HARQ in the base station necessitating data buffering at the air interface. This introduces a potential bottleneck to end-to-end communication. Hence, buffer management at the air interface is crucial for end-to-end QoS support of multimedia services with multiplexed parallel diverse flows such as video and data in the same end-user session. The dynamic buffer management scheme for HSDPA multimedia sessions with aggregated real-time and non real-time flows is investigated via extensive HSDPA simulations. The impact of the scheme on end-to-end traffic performance is evaluated with an example multimedia session comprising a real-time streaming flow concurrent with TCP-based non real-time flow. Results demonstrate that the scheme can guarantee the end-to-end QoS of the real-time streaming flow, whilst simultaneously protecting the non real-time flow from starvation resulting in improved end-to-end throughput performance
Traffic integration in personal, local and geograhical wireless networks
Currently, users identify wireless networks with the first and second generation of cellular-telephony networks. Although voice and short messaging have driven the success of these networks so far, data and more sophisticated applications are emerging as the future driving forces for the extensive deployment of new wireless technologies. In this chapter we will consider future wireless technologies that will provide support to different types of traffic including legacy voice applications, Internet data traffic, and sophisticated multimedia applications. In the near future, wireless technologies will span from broadband wide-area technologies (such as satellite-based network and cellular networks) to local and personal area networks. Hereafter, for each class of networks, we will present the emerging wireless technologies for supporting service integration. Our overview will start by analyzing the Bluetooth technology that is the de-facto standard for Wireless Personal Area Networks (WPANs), i.e. networks that connect devices placed inside a circle with radius of 10 meters. Two main standards exist for Wireless Local Area Networks (WLANs): IEEE 802. and HiperLAN. In this chapter we focus on the IEEE 802.11 technology, as it is the technology currently available on the market. In this chapter, after a brief description of the IEEE 802.11 architecture, we will focus on the mechanisms that have been specifically designed to support delay sensitive traffics
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