School of Computer Science and Informatics

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Browsing School of Computer Science and Informatics by Subject "3.5 G cellular network"

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    End-to-End QoS Improvement of HSDPA End-User Multi-Flow Traffic Using RAN Buffer Management
    (IEEE, 2008-11) Yerima, Suleiman; Al-Begain, K.
    High speed downlink packet access (HSDPA) was introduced to UMTS radio access segment to provide higher capacity for new packet switched services. As a result, packet switched sessions with multiple diverse traffic flows such as concurrent voice and data, or video and data being transmitted to the same user are a likely commonplace cellular packet data scenario. In HSDPA, radio access network (RAN) buffer management schemes are essential to support the end-to-end QoS of such sessions. Hence in this paper we present the end-to-end performance study of a proposed RAN buffer management scheme for multi-flow sessions via dynamic system-level HSDPA simulations. The scheme is an enhancement of a time-space priority (TSP) queuing strategy applied to the node B MAC-hs buffer allocated to an end user with concurrent real-time (RT) and non-real-time (NRT) flows during a multi-flow session. The experimental multi- flow scenario is a packet voice call with concurrent TCP-based file download to the same user. Results show that with the proposed enhancements to the TSP-based RAN buffer management, end-to-end QoS performance gains accrue to the NRT flow without compromising RT flow QoS of the same end user session.
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    Performance modelling of a queue management scheme with rate control for HSDPA
    (2007-06) Yerima, Suleiman; Al-Begain, K.
    High Speed Downlink Packet Access (HSDPA) is being increasingly deployed to enhance UMTS Radio Access Networks. Scheduling of Node B (base station) buffered user data for transmission over a shared radio channel is a key HSDPA functionality which enables queue management techniques to be utilized to improve QoS provisioning for mixed ‘multimedia’services. Thus, we have previously proposed and studied a Time-Space Priority (TSP) buffer management scheme for ‘multimedia’QoS control in HSDPA Node B. In this paper the scheme is extended to incorporate a threshold-based rate control mechanism which provides flow control between the RNC and Node B entities over the Iub interface to improve the QoS performance of non-real-time (NRT) streams in the multimedia flow. Mathematical and simulation models are developed for comparative analysis with the previously studied TSP scheme lacking rate control. The results demonstrate the performance improvement achievable with the joint implementation of TSP queue management scheme and Iub flow control mechanism(s).