Scheduling Support for Mixed VoIP and Web Traffic over HSDPA

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.

This paper provides methods for packet scheduling that designed for VoIP in a mixed traffic scenario over high-speed downlink packet access (HSDPA) in WCDMA. In the interested mixed traffic scenario voice packets are transmitted together with 5 background best-effort (BE) data users. The proposed packet scheduling schemes in such a mixed traffic environment are based on a proportional fair (PF) packet scheduling algorithm, to be more specifically, they are two resource allocation methods for BE data user. The performance is evaluated with a quasi-static system level simulator. Performance with a LMMSE advanced receivers is also addressed. The results indicate that with the proposed scheduling algorithm 2 in this paper the VoIP capacity in a mixed traffic scenario can be up to 106 users with a delay budget 80 ms, which is approximately maintained as that of VoIP single mode. At the same time, a rather good background BE performance can be obtained. With the proposed algorithm 1 the VoIP capacity can reach 101 users per cell. However a better background BE performance than algorithm 2 can be obtained.

In order to improve support for higher speed data, 3GPP has developed an evolution of UNTS based on WCDMA known as HSDPA(high speed downlink packet access). The target of HSDPA is to provide service for not only voice user but also higher speed data users. For HSDPA, there are two important parameters, which are the rate ratio and the power ratio between higher speed data signal and voice data signal. In this article, we deduced two useful conclusions, which are based on the research of the relationship between the rate ratio and the power ratio. One of the two conclusions is that the transmission power is in positive proportional to data rate when the user numbers of higher speed data is high, which would result in dramatic interference of multi-user. The other is that the same capacity can be achieved by only using half transmission power when there is one higher speed data user over one transmission time interval. Based on the two conclusions, the feasibility of HSDPA is studied. We found that it is impossible for HSDPA to provide simultaneously service for multiple high-speed data users and voice users. A feasible CDMA/TDMA reform scheme is proposed, which can achieve the design goal of WCDMA HSDPA. The reform scheme employs the method of time domain multiplexing(TDM) to realize the transmission of high speed data over a special CDMA channel. The reform scheme can increase dramatically downlink capacity, improve spectral efficiency, and also reduce system cost by employing simple interference eliminator.

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 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.

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.

In 3GPP W-CDMA, high speed downlink packet access functionality is implemented using the high speed downlink shared channel (HS-DSCH) and its associated control channels. In this paper, we describe the overall structure of HS-DSCH and its control channels: the high speed shaped control channel (HS-SCCH) and the high speed uplink DPCCH (HS-DPCCH). We then present detailed link and system simulation results supporting the control channel design. In addition, a new power control method to support HS-DPCCH operation during soft-handoff is described. The proposed algorithm automatically adjusts the power ratio between the control and data channels based on propagation conditions and outperform the conventional scheme with minimum impact to the DPDCH performance.

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) 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

Only best-effort traffic was supported by traditional packet switching networks, but newer applications need network services that allow an end-client to transport data with performance guarantees. The choice of packet-scheduling algorithm used at switching nodes is crucial in providing Quality of Service (QoS). This paper proposes a downlink packet scheduling algorithm for QoS provisioning in High Speed Downlink Packet Access (HSDPA) based UMTS networks. In HSDPA, a single logical channel is shared amongst multiple contending users. Besides better link utilization, scheduling disciplines seek to achieve fair allocation of this shared resource. However, these two criteria can potentially be in conflict. The scheduling algorithm proposed in this paper, Wireless Fair High Speed Scheduling, addresses this conflict. The basic idea is to allocate the wireless channel fairly amongst users, even during short time scales, according to their data rate requirements. Simulation results show that the proposed scheduling algorithm provides better link utilization, as well as long-term and short-term fairness amongst users, even under heavy load conditions.

This paper proposes a novel packet scheduling algorithm for delay constraint traffic on high speed down link packet access (HSDPA) and also a packet scheduler for this algorithm. In this packet scheduling algorithm, we consider both the delay constraint and the throughput for each traffic class while maximizing the system capacity. Considering the delay constraint and the throughput simultaneously, our method can guarantee different quality of service (QoS) for each traffic class. Finally, in order to demonstrate the performance of our proposed algorithm, we compare our algorithm with the proportional fairness (PF) method and round robin (RR) method by system simulations. Numerical results show that system performance can be significantly improved employing our algorithm compared to that with the PF or RR method.

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.

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.

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.

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.