Fair resource allocation with guaranteed statistical QoS for multimedia traffic in wideband CDMA cellular network

A dynamic fair resource allocation scheme is proposed to efficiently support real-time and non-real-time multimedia traffic with guaranteed statistical quality of service (QoS) in the uplink of a wideband code-division multiple access (CDMA) cellular network. The scheme uses the generalized processor sharing (GPS) fair service discipline to allocate uplink channel-resources, taking into account the characteristics of channel fading and intercell interference. In specific, the resource allocated to each traffic flow is proportional to an assigned weighting factor. For real-time traffic, the assigned weighting factor is a constant in order to guarantee the traffic statistical delay bound requirement; for non-real-time traffic, the assigned weighting factor can be adjusted dynamically according to fading, channel states and the traffic statistical fairness bound requirement. Compared with the conventional static-weight scheme, the proposed dynamic-weight scheme achieves capacity gain. A flexible trade-off between the GPS fairness and efficient resource utilization can also be achieved. Analysis and simulation results demonstrate that the proposed scheme enhances radio resource utilization and guarantees statistical QoS under different fairness bound requirements.     

Adaptive QoS scheduling in wireless cellular networks

Quality of service (QoS) has been always controversial in resource shared networks. Scheduling as a packet prioritizing mechanism at Data Link Layer (DLL) contributes to QoS guarantee provisioning significantly. In this paper, a novel packet scheduler is developed in wireless cellular networks. The proposed scheme provides QoS-guaranteed service for the applications running on the sensor nodes in all the three aspects of QoS, i.e. data rate, packet loss and packet delay with regard to jitter simultaneously. We establish a three-dimensional space with certain basis vectors for QoS and introduce the efficient point of performance in terms of QoS provisioning in that space. Then we develop a generalized metric, the QoS-deviation, which is the Euclidean distance between the QoS work point of flows and the QoS efficient point in the proposed space. Based on this metric, a novel scheduling approach, namely AQDC, is designed which makes it possible to tune the trade-off between QoS provisioning and throughput optimization in an adaptive manner depending on the current Cell QoS-deviation level (CDL). Furthermore, we also develop another scheduler, namely ARTC, which is the residual-time version of the AQDC scheduler. Finally, a QoS-deviation-based CAC policy will be introduced which can be applied to all schedulers without any consideration about their structure and can be employed in cellular packet switched networks.     

Dynamic resource scheduling (DRS): a multimedia QoS framework for W‐CDMA

Multi‐media support is an important feature of third generation (3G) wireless communication systems, and Quality of Service (QoS) is a crucial issue, as in any other networking environment. In this paper, the QoS issues in the wireless last‐mile is investigated for 3G systems based on Wideband‐Code division multiple access (W‐CDMA). Supporting multiple rates in the CDMA environment introduces the power assignment problem, which is coupled with the bandwidth and error QoS parameters. Also, multi‐media traffic flows should be classified and serviced in such a way to provision delay guarantees. In this paper, a new framework, namely dynamic resource scheduling (DRS), is described and extensively studied. In order to serve multi‐media services with different requirements, a family of nine algorithms has been developed within the DRS framework. These algorithms can be categorized with respect to single or prioritized queuing architectures, fixed or variable rate bandwidth and power allocation, and variable spreading gain or multi‐code spreading strategies. The paper presents the performance of the DRS algorithms in comparison with each other and with conventional scheduled‐CDMA (S‐CDMA) and proposed schemes in the W‐CDMA standard. The performance for error and throughput QoS provisioning and power control dynamics are explored; advantages, disadvantages and limitations of the algorithms are discussed. The DRS framework is concluded to be a promising QoS architecture, with a simple, flexible, scalable structure that can be configured according to a given traffic scenario. Copyright © 2004 John Wiley & Sons, Ltd.     

Multiple-access interference processes are self-similar in multimedia CDMA cellular networks

We consider bursty data communications in code-division multiple-access (CDMA) cellular networks. The significant fluctuation of the cochannel multiple-access interference (MAI) in such systems makes it very challenging to carry out radio resource management. A main goal of this paper is to obtain a fundamental understanding of the temporal correlation structure of the MAI, which plays a crucial role in effective resource allocation. To this end, we take a cross-layer design approach, and characterize the stochastic MAI process while taking into account both the burstiness of data traffic and time-varying channel conditions. Our main results reveal that under standard assumptions on ON/OFF traffic flows and fading channels, the MAI process exhibits scale-invariant burstiness and is "self-similar" (with Hurst parameter 1/2相似文献   

A fair optimization scheduling scheme for IEEE 802.16 networks in multimedia applications

IEEE 802.16 networks are designed based on differentiated services concept to provide better Quality of Service (QoS) support for a wide range of applications, from multimedia to typical web services, and therefore they require a fair and efficient scheduling scheme. However, this issue is not addressed in the standard. In this paper we present a new fair scheduling scheme which fulfills the negotiated QoS parameters of different connections while providing fairness among the connections of each class of service. This scheme models scheduling as a knapsack problem, where a fairness parameter reflecting the specific requirements of the connections is defined to be used in the optimization criterion. The proposed scheduler is evaluated through simulation in terms of delay, throughput and fairness index. The results show fairness of the scheduling scheme to all connections while the network guarantees for those connections are fulfilled.     

Wireless-adaptive fair scheduling for multimedia stream

As packet cellular networks are expected to support multimedia services, the authors incorporate the multimedia QoS requirements into the design of a new scheduling algorithm. The proposed wireless-adaptive fair scheduling tries to allocate time slots for each user with fair share by considering the varying channel condition while reflecting the stream requirements and achieving high throughput.     

Call admission control in wideband CDMA cellular networks by using fuzzy logic

In this paper, a novel call admission control (CAC) scheme using fuzzy logic is proposed for the reverse link transmission in wideband code division multiple access (CDMA) cellular communications. The fuzzy CAC scheme first estimates the effective bandwidths of the call request from a mobile station (MS) and its mobility information, then makes a decision to accept or reject the connection request based on the estimation and system resource availability. Numerical results are given to demonstrate the effectiveness of the proposed fuzzy CAC scheme in terms of new call blocking probability/handoff call dropping probability, outage probability, and resource utilization.     

Opportunistic scheduling for multiclass services with different QoS constraints in wireless data networks

In this letter, we focus on the problem with the objective to maximize the system performance, while guaranteeing specified QoS constraints for multiple user classes in wireless data networks. First, we propose two opportunistic scheduling algorithms that exploit time-varying channel conditions for the special two-constraint case, and then propose an opportunistic scheduling algorithm for the general case. Simulation results illustrate that the proposed scheduling algorithms guarantee the different constraints, and achieve high-system performance that is close to the true optimal value using a known general-purpose optimization package, lingo.     

基于蚂蚁算法的CDMA多媒体数据规划协议

本文讨论了MC-CDMA多媒体数据规划协议,多媒体数据按BER指标分类,根据各类数据BER要求,采用蚂蚁算法对用户分组数据进行规划.对照传统的"先到先服务"(FCFS)方法,进行了仿真分析,结果表明平均吞吐率、平均时延及平均丢包率均有改善.     

Optimal resource management in wireless multimedia wideband CDMA systems

This paper proposes a scheme of optimal resource management for reverse-link transmissions in multimedia wideband code-division multiple-access (WCDMA) communications. It is to guarantee quality-of-service (QoS) by resource (transmit power and rate) allocation and to achieve high spectral efficiency by base-station assignment. This approach takes the form of a nonlinear-programming large-scale optimization problem: maximizing an abstraction for the profit of a service provider subject to QoS satisfaction. Solutions for both single-cell and multicell systems are investigated. The single-cell solution has the advantage of low complexity and global convergence in comparison with the previous work. Maximum achievable throughput (capacity) of a single cell is mathematically evaluated and used as the benchmark for performance measure of multicell systems. For multicell systems, due to its max-max structure, solving the optimization problem directly entails a high-computational complexity. Instead, the problem is reformulated to a mixed integer nonlinear-programming (MINLP) problem. Then, binary variables indicating base-station assignments are relaxed to their continuous analogs to make a computer solution feasible. Furthermore, approximations can be made to make the resource-management scheme less computationally complex and allow its partial decentralization. The sensitivity of the proposed scheme to path-gain estimation error is studied. Simulation results are presented to demonstrate the performance of the proposed scheme and the throughput improvement achieved by combining resource allocation with base station assignment.     

Performance of wideband CDMA systems supporting multimedia traffic

We evaluate the performance of wideband CDMA cellular systems providing different classes of multimedia traffic and supporting user mobility. A Markovian teletraffic model of the user dynamics is developed. Constraints are imposed in the model which account for the multiple access interference among active users. Results are shown in terms of call blocking probabilities and average number of active connections. The methodology proposed is a useful tool for the design and planning of third generation cellular systems     

Planning OBS networks with QoS constraints

The design of OBS networks that guarantee QoS provisioning for different classes of traffic is a major topic under current research. In this work we formulate a unified framework for studying QoS in OBS networks with a GMPLS-based control plane. We use this framework in order to investigate two problems. First, the configuration of the parameters of an aggregation strategy so that a given Forwarding Equivalency Class observes its corresponding QoS requirements. Second, we address the problem of planning a whole OBS network given a series of QoS constraints for each one of the Forwarding Equivalency Classes in the network. The presented QoS framework constitutes a valuable tool for studying QoS-related issues in OBS networks.     

Scheduling in multimedia CDMA wireless networks

Wireless systems in the future will have to provide multimedia services where different users have different physical-layer quality of service (QoS) requirements (e.g., bit energy per interference power density, E/sub b//N/sub 0/, or bit error rate and power constraints) and network-layer QoS requirements (e.g., delay bound, delay-jitter, throughput, and loss). We investigate the use of power control, processing gain and/or multiple codes, and scheduling in CDMA systems to accommodate these diverse service requirements. We first show that the instantaneous capacity region, given in terms of the set of user bit rates that can be supported simultaneously subject to peak power and E/sub b//N/sub 0/ constraints, is nonconvex. This suggests that by time-sharing the channel, one may be able to get better system throughput. We define the capacity region as the convex hull of the instantaneous capacity region and we show that it may be obtained by time sharing between operating points, where each user either uses full power or is silent (bang-bang control). We then consider the problem of scheduling so as to meet prespecified delay bounds or minimum service curve requirements for traffic streams, which are specified in terms of a traffic profile such as a sigma-rho constraint (enforced by a leaky bucket) and a guarantee that the system is stable.     

Monitoring QoS distribution in multimedia networks

This paper presents two schemes, relevant monitor (RM)‐based and improved relevant monitor (IRM)‐based, for QoS distribution monitoring. With these schemes, when monitoring a real‐time flow, a network manager can locate relevant monitors that are metering the flow. Copyright © 2000 John Wiley & Sons, Ltd.     

An FDD wideband CDMA MAC protocol with minimum-power allocation and GPS-scheduling for wireless wide area multimedia networks

A frequency division duplex (FDD) wideband code division multiple access (CDMA) medium access control (MAC) protocol is developed for wireless wide area multimedia networks. In order to reach the maximum system capacity and guarantee the heterogeneous bit error rates (BERs) of multimedia traffic, a minimum-power allocation algorithm is first derived, where both multicode (MC) and orthogonal variable spreading factor (OVSF) transmissions are assumed. Based on the minimum-power allocation algorithm, a multimedia wideband CDMA generalized processor sharing (GPS) scheduling scheme is proposed. It provides fair queueing to multimedia traffic with different QoS constraints. It also takes into account the limited number of code channels for each user and the variable system capacity due to interference experienced by users in a CDMA network. To control the admission of real-time connections, a connection admission control (CAC) scheme is proposed, in which the effective bandwidth admission region is derived based on the minimum-power allocation algorithm. With the proposed resource management algorithms, the MAC protocol significantly increases system throughput, guarantees BER, and improves QoS metrics of multimedia traffic.     

Downlink scheduling optimization in CDMA networks

The problem of allocating radio resources in the downlink of a code-division multiple access (CDMA) network is studied. The modulation and coding schemes, numbers of multicodes, and transmit powers used for all mobile stations (MS) are jointly chosen so as to maximize the total transmission bit rate, subject to certain constraints. Based on the discrete and nonlinear nature of the proposed model, a mixed-integer nonlinear programming optimization problem is formulated. It is shown that the optimal allocation generally involves simultaneous transmissions to several MS. A scheduler which uses knowledge of MS traffic loads is also proposed and shown to yield a significant improvement in throughput.     

Approximate fair bandwidth sharing in high-speed multimedia networks

Existing fair-queuing algorithms use complicated flow management mechanisms, thus making them expensive to deploy in current high-bandwidth networks. In this paper we propose a scalable SCORE (stateless core) approach to provide fair bandwidth sharing for a traffic environment composed of TCP and UDP flows. At an edge router, the arrival rates of each flow are estimated, each packet then being labelled with this estimate. The outgoing link’s fair share at a router is estimated based on UDP traffic. Probabilistic dropping is used to regulate those flows that send more than the fair share. At a core router, all the functions performed by an edge router are repeated, excluding the flow rate estimation. The simulation results show that the degree of fairness achieved by the proposed solution is comparable to that of other algorithms, but with a lower implementation cost.     

Radio resource management for downlink multimedia services in TDMA/CDMA interference-limited cellular networks

This paper addresses the radio resource management (RRM) structure and efficient dynamic capacity allocation techniques for hybrid TDMA/ CDMA mobile cellular networks to support downlink multimedia services with different quality-of-service (QoS) requirements in an interference-limited environment. Various burst-driven timeslot-code assignment algorithms suitable for distributed processing are proposed to achieve high system capacity in terms of b/s/Hz/cell while maintaining a required percentage of satisfied users. Simulation results for various traffic scenarios are used for performance evaluation and comparison. The impacts of bursty WWW traffic on speech performance are also examined. It is shown that interference information can be used in timeslot-code assignment to significantly improve the system performance. Based on the received interference information, the minimum instantaneous power (MIP) algorithm aims to assign timeslot-codes that minimize the required transmitted power to maintain a target SINR. The MIP can provide an increase of 23% in system capacity. By considering to reduce both potentially received and generated interference in timeslot-code assignment, the Minimum Sum of Path-loss Ratios (MS-PLR) algorithm can further offer an additional capacity increase of 24%.     

QoS provisioning for multimedia wireless networks

As we move towards IP-based multimedia wireless networks with voice, video and data convergence, quality of service (QoS) provisioning will become an increasingly challenging task. One implication is that greater emphasis on managing the call admission and overall network resources will be needed. This paper presents a conservative and adaptive quality of service (CAQoS) framework for provisioning the QoS for both real-time and non-real-time traffic in a multimedia wireless network. Unlike most conventional schemes, which gradually scale down the bandwidth of ongoing connections to accommodate new connection/hand-off requests, CAQoS introduces an early scaling-down of bandwidth for new connections based on a designated provisioning model. The performance of a CAQoS system is evaluated through simulations of a realistic wireless environment. Simulation results show that CAQoS meets our design goals and outperforms conventional schemes.     

QoS-oriented packet scheduling for wireless multimedia CDMA communications

In the third-generation (and beyond) wireless communication systems, there will be a mixture of different traffic classes, each having its own transmission rate characteristics and quality-of-service (QoS) requirements. In this paper, a QoS-oriented medium access control (MAC) protocol with fair packet loss sharing (FPLS) scheduling is proposed for wireless code-division multiple access (CDMA) communications. The QoS parameters under consideration are the transmission bit error rate (BER), packet loss, and delay requirements. The MAC protocol exploits both time-division and code-division statistical multiplexing. The BER requirements are guaranteed by properly arranging simultaneous packet transmissions and controlling there transmit power levels, whereas the packet loss and delay requirements are guaranteed by proper packet scheduling. The basic idea of FPLS is to schedule the transmission of multimedia packets in such a way that all the users have a fair share of packet loss according to their QoS requirements, which maximizes the number of the served users under the QoS constraints. Simulation results demonstrate effectiveness of the FPLS scheduler, in comparison with other previously proposed scheduling algorithms.