Queuing Models for Dimensioning Interactive and Streaming Services in High-Speed Downlink Packet Access Networks

Fast packet scheduling is a key feature of packet-based data services which are 3G/4G wireless networks such as Enhanced Data rates for GSM Evolution, High-Speed Downlink Packet Access (HSDPA), and High Data Rate. In this paper, we propose Anticipated Proportionally Optimal (APO), a new packet scheduling scheme with Quality of Service (QoS) support for hybrid of real and non-real-time services over HSDPA networks. The APO scheduling algorithm is based on the effective channel anticipation model. In contrast to the traditional schemes, the proposed method is implemented based on a cyclic non-work-conserving discipline. Simulation results indicate capability of proposed scheme to maximize the channel usage efficiency compared to other exist scheduling methods. Results also present fair tradeoff between channel capacity and desired QoS for real-time services.

In this paper, we describe the novel concept of broadcast and multicast (BCMC) transmission over high speed downlink packet access (HSDPA), a shared high-speed packet data channel on the downlink defined in the Universal Mobile Telecommunications System (UMTS) standard. We show that the unique features of HSDPA such as link adaptation, channel-sensitive scheduling, and hybrid automatic repeat request (HARQ) can be used to provide performance gains over conventional multimedia broadcast multicast service (MBMS) transmission on the forward access channel (FACH) channel. We address various aspects of system design and performance in the design of a BCMC system over HSDPA, and present a detailed performance analysis using system level simulations. Some of the main objectives of our BCMC design are to enable broadcast and multicast services on HSDPA networks without requiring significant changes to the HSDPA standard in 3rd Generation Partnership Project (3GPP), and to ensure that the solution is backward-compatible with Release 5 HSDPA mobile devices.

In Wideband Code Division Multiple Access (WCDMA) networks the Signaling Radio Bearer (SRB) is transmitted downlink to inform the user i.a. when it needs to make a handover. When transmitting e.g. Voice over IP (VoIP) on High Speed Downlink Packet Access (HSDPA) SRB is mapped on HSDPA user data channel, high-speed downlink shared channel (HS-DSCH) in order to maximize voice capacity. The lack of support for soft handover (SHO) of HS-DSCH may compromise the reception of SRB and thus also a possible incoming serving HSDPA cell change command especially at the cell borders. This can lead to serious VoIP service degradation due to prolonged camping on a poor cell and in the worst case even to call dropping, if the cell change command is not received before VoIP call drop criterion is met. This paper considers the performance of SRB transmission on source cell HS-DSCH during a handover process. Also a strategy of transmitting the serving cell change command from the target cell is analyzed. The study is done by the means of fully dynamic system simulations and they consider both macro-cell and manhattan scenarios. The results show that a relatively low SRB/handover error rate is experienced in a macro cell scenario but in a more challenging manhattan scenario the error rate is higher. Transmitting the serving cell change command from the target cell HS-SCCH results in similar handover failure rates in manhattan scenario than using SRB on HS-DSCH in macro-cell scenario when static power allocation for HS-SCCH is in use.

The various link adaptation techniques employed by High Speed Downlink Packet Access (HSDPA) in the third generation (3G) networks augment the bandwidth oscillation, which is identified as one of the most important factors resulting in the throughput deterioration of Transmission Control Protocol (TCP). In this paper, we firstly explain why the bandwidth oscillation degrades the TCP performance through a special simulation experiment. Subsequently, a split connection Window Adaptation TCP Proxy is proposed to improve the TCP throughput over HSDPA networks. In this solution, the built-in attributes of HSDAP system are sufficiently utilized. In order to effectively use the precious cellular link resources, the length of the queue connected with it is intentionally kept around the reference value through adjusting the sending window size of TCP proxy based on the dynamic values of varying bandwidth. A discrete-time stochastic state space model is formulated to analyze the system stability. The validity of enhanced scheme is verified through simulation experiments. The performance of TCP proxy is compared with the standard TCP protocol. The numerical results show that our TCP proxy is able to keep the cellular link utilization over 90%, and to improve TCP throughput by 100% under most conditions.

In this paper traffic steering between a High-Speed Downlink Packet Access (HSDPA) network and a 3GPP Long Term Evolution (LTE) network with different carrier frequencies is investigated. First, two traffic steering algorithms, relying on static network information, are assessed from a traffic theoretical point of view and numerically. Furthermore, numerical analysis of two traffic steering algorithms, relying on dynamic information such as user SINR and cell load, is also performed. It is shown that the dynamic traffic steering algorithms outperform the static methods in terms of end user performance. Finally, it is investigated how the LTE terminal penetration affects the performance of the proposed traffic steering algorithms. For low LTE terminal penetration all LTE capable terminals should be pushed to the LTE network, and for high LTE terminal penetration a more dynamic traffic steering scheme should be used.

The provision of data services in 3G systems requires spectral efficiency solutions to increase the capacity of the radio access network as well as support for high data rates. In this context, the 3GPP introduces a new feature in the release 5 specifications denominated high speed downlink packet access (HSDPA). The HSDPA concept appears as an umbrella of features to improve both user and system performance. The concept includes a reduction of the transmission time interval (TTI) to 2 ms, an adaptive modulation and coding (AMC) scheme, and a fast physical layer hybrid ARQ mechanism. In this paper the objective is to analyze the HSDPA performance for streaming, interactive, and background services. Relevant characteristics such as the QoS demands of the different traffic classes, the throughput and delay characteristics has been analyzed and compared with shared channel. We also propose a new packet-scheduling scheme for HSDPA transmission, which improves the overall performance and fairness among the packet users.

High speed downlink packet access (HSDPA) was originally introduced in release 5 of WCDMA to boost data rates of packet switched traffic in the downlink. With increasing demand for streaming services and recent efforts to provide mobile TV, the standard has also been considered for delivering streaming services over cellular networks. While much attention has been paid to optimizing transmission of non real time application, this paper aims at providing a comprehensive study of particular requirements and performance aspects of transmission of streaming services over HSDPA. We compare performances of different scheduling algorithms in pure streaming scenarios for constant bit rate as well as variable bit rate streams and different streaming rates. We further study the impact of code multiplexing of different streaming users on the system performance and examine the system behavior when both streaming and best effort services are present.

This paper discusses methods for improving the effectiveness of delivering voice traffic over High-Speed Downlink Packet Access (HSDPA) network by employing transmission diversity with Single-Frequency Dual-Cell (SF-DC) Aggregation that is part of the Multiflow specification. SF-DC Aggregation allows the user to be served at the same time by two different cells. The enhancements discussed in the paper capitalize strongly on the availability of the composed Channel Quality Indication (CQI) feedback at both serving cells. According to the results obtained from the network simulations, the ability to select the better channel for each voice transmission significantly decreases the required transmission power of the cell, thus also improving the residual cell capacity available for best effort (BE) traffic. The required updates are completely software-based and are applied only in the access network, making them transparent to user terminal.

High-speed downlink packet access (HSDPA) achieves high data rates and high spectral efficiency by using adaptive modulation and coding schemes and employing multicode CDMA. In this paper, we present opportunistic algorithms for scheduling HSDPA users and selecting modulation/coding and multicode schemes that exploit channel and buffer variations to increase the probability of uninterrupted media play-out. First, we introduce a stochastic discrete event model for a HSDPA system. By employing the discrete event model, we transform the scheduling problem of providing uninterrupted play-out to a feasibility problem that considers two sets of stochastic quality-of-service (QoS) constraints: stability constraints and robustness constraints. A methodology for obtaining a feasible solution is then proposed by starting with a so-called stable algorithm that satisfies the stability QoS constraints. Next, we present stochastic approximation algorithms that adapt the parameters of the stable algorithm in a way that a feasible point for the robustness QoS is reached within the feasibility region of the stability QoS

This article investigates the efficient transmission of file download services to several users simultaneously in 3G mobile networks with HSDPA (High-Speed Downlink Packet Access) and MBMS (Multimedia Broadcast Multicast Services). HSDPA supports high speed point-to-point (p-t-p) transmissions (up to several Mb/s), whereas with MBMS the same content can be transmitted with a point-to-multipoint (p-t-m) connection to multiple users in a unidirectional fashion. Multicast delivery can be implemented through only p-t-p transmissions with HSDPA, a single p-t-m transmission with MBMS, or using both jointly in a hybrid approach by employing HSDPA for error repair of the MBMS p-t-m transmission. We investigate the optimum HSDPA and MBMS transmission configuration when they are used separately, and the trade-off between the initial MBMS file p-t-m transmission and the HSDPA error repair for the hybrid delivery. The approach of minimizing the transmission energy (product of the transmit power times the transmission time) to achieve a target file acquisition probability (percentage of users that successfully receive the file) has been adopted.

High-speed downlink packet access (HSDPA) is an interface of UMTS systems for data communication. It combines 16-QAM modulation with low spreading factors to achieve high data rates. Generalized RAKE (G-RAKE) receiver is an advanced receiver, which can be employed in HSDPA to obtain reliable communication. In this work, we investigate iterative methods, which reduce overall complexity requirements of the G-RAKE receiver, without sacrificing its performance. The names of the methods are The Gauss-Seidel (GS), Successive Over-Relaxation (SOR), Conjugate Gradient (CG), and Preconditioned Conjugate Gradient (PCG). Our simulation results show that the PCG method provides the best trade-off between the complexity and required conditions.

HSDPA (high-speed downlink packet access), introduced in WCDMA release 5, provides a high-bandwidth shared channel with short transmission time interval (TTI). The short TTI together with appropriate scheduling enable HSDPA to support efficient multiplexing of traffic. We explain the performance of four scheduling algorithms when transmitting a traffic mix consisting of both conversational (VoIP) traffic and background (Web) traffic over the high-speed downlink shared channel (HS-DSCH) of HSDPA. We consider both cell throughput and user satisfaction. The proportional fair (PF), the maximum rate (MR) scheduler and two extended versions of MR, are tested for different VoIP scheduling delay budgets and varying load. To understand the behaviour of the schedulers, we use the ns-2 simulator extended with a model of HS-DSCH to simulate a mixed traffic scenario. Our results show that a scheduler that gradually increases the VoIP priority and considers the user's current possible rate, performs well. A more drastic increase in VoIP priority is however needed when the delay budget is short. Furthermore, attempting to uphold quality for both VoIP and Web traffic makes the system sensitive to overload situations.

In recent years, the growth of smart phone industry drives its users to demand better quality multimedia services while achieving faster internet speeds. With a higher number of subscribers and more data hungry applications, there is a need to improve the current 3G HSDPA data rate until the 4G network is fully implemented globally. Therefore, the aim of this thesis is to improve the downlink data rate of the HSDPA system throughput through both transmitter and receiver optimisations while balancing the complexities of the optimisation algorithms. Initially, improving system throughput through power allocation strategies is investigated in this thesis. Current schemes proposed in the literature that use Equal SINR Equal Rate (ESER) allocation can improve the system throughput for single rate allocation but require a rather high complexity. In this thesis, a System Value (SV) criterion is proposed to decrease the traditional ESER allocation method while achieving similar system throughput performance. To further increase the system throughput, a Successive Interference Cancellation (SIC) receiver is proposed which not only improves the data rate but also has a reduced complexity. The proposed SIC receiver can be used in conjunction with both ESER allocation schemes as well as equal energy allocation schemes. Another transmitter optimisation strategy is to improve the signature sequences. A signature sequence design that minimises correlations between the sequences while reducing the Inter-Symbol Interference (ISI) and noise is proposed. To reduce the amount of channel state information required, a signature sequence selection method which removes the signature sequences that are heavily a ected by interference is also proposed. The proposed optimisation strategies have been veri ed through MATLAB simulations. Moreover, practical measurements using the National Instruments (NI)-PXIe testbed have been carried out for the proposed SIC algorithm which further con rm its e ectiveness in a real world environment.

This paper presents an analytical model of the cell and user throughput of high-speed downlink packet access (HSDPA) that can be used to compare the performance and efficiency of various schedulers. The focus is on the proportional fair (PF), score-based (SB), and Max C/I schedulers. The radio channel is assumed to be a composite multipath/shadowing channel, with the path amplitude following a Nakagami distribution. The effect of the correlation between paths on the HSDPA throughput performance is taken into account in the modeling. The analytical model is confronted with a simulation using the NS2 network simulator and shown to provide reasonably close results to the simulation in view of the modeling assumptions.

In the HSDPA (high-speed downlink packet access) Iub transport network (TN) which connects the radio network controller with base stations (node Bs), congestion control is needed. Because of the TN?s often narrow resources, fairness of resource sharing is an important issue. Basic Additive Increase multiplicative decrease (AIMD) congestion control guarantees convergence to fairness in the long run; all flows converge to an equal share of resources in steady state, where no flows join or leave. However, incoming flows decrease the level of fairness, that is why transient fairness should be taken into account as well. This paper proposes a method which provides fairness-optimal initial rate for incoming HSDPA flows. The proposed method improves average fairness. The method can be applied in a rate based congestion control where flows share the same bottleneck. The paper also gives a general solution for fairness-optimal initial rate in case of second-order fairness measures.