Achievable QoS and scheduling policies for integrated services wireless networks

Dynamic bandwidth allocation for 3G wireless systems—A fuzzy approach

Several scheduling algorithms have been proposed for the downlink of a Code Division Multiple Access (CDMA) system with High Data Rate (HDR). Modified Largest Weighted Delay First (M-LWDF) scheduling algorithm selects a user according to the user current channel condition, user head-of-line packet delay and user Quality of Service (QoS) requirement. Proportional Fair (PF) scheduling algorithm has also been proposed for CDMA/HDR system and it selects a user according to the ratio of the user current channel rate and the user average channel rate, which provides good performance in terms of fairness. However, when variable bit rate (VBR) traffic is considered under different channel conditions for each user, both schedulers' performance decrease. M-LWDF scheduler can not guarantee the QoS requirement to be achieved and PF scheduler can not achieve a good fairness among the users. In this work, we propose a new scheduling algorithm to enhance M-LWDF and PF schedulers performance. Proposed scheduler selects a user according to the user input traffic characteristic, user current channel condition and user QoS requirement, which consists of a delay value with a maximum violation probability. We consider the well-known effective bandwidth expression, which takes into account the user QoS requirement and the user input traffic characteristics, to select a user to be scheduled. Properties of the proposed scheduling algorithm are investigated through simulations with constant bit rate (CBR) and VBR flows and performance comparisons with M-LWDF and PF schedulers. The results show a better performance of the proposed scheduler compared with M-LWDF and PF schedulers.

Real time traffic in Virtual Private Network (VPN) connections can tolerate minor violations to their end to end delay bounds. This allowed Service Providers (SP) to increase the number of admitted requests by taking advantage of the statistical multiplexing behavior of such traffic. Usually, each VPN connection has different QoS requirements such as delay and violation probability bounds. Also, each set of requirements are to be fulfilled in isolation, independently from requirements of other connections. Several Measurement Based Admission Control (MBAC) algorithms were designed to meet the soft real time services quality of service (QoS) requirements. However, intensive studies of the existing MBAC algorithms revealed that almost none of these algorithms can meet the distinct violation probability requirements of the connections. This motivated designing a novel algorithm that is capable of reserving resources to distinctly satisfy the desired violation probability and delay bounds of a connection's QoS requirements. The proposed algorithm is an online distributed algorithm. It is based on measuring the delay of the link traffic. The empirical histogram of the measured delay is fitted to a gamma distribution, which is used to calculate the required bandwidth to be reserved in order to meet the connections' QoS requirements. The simulation results for evaluating the algorithm performance show that the algorithm is capable of meeting the distinct QoS requirements of the connections while admitting two to three times the number of connections a deterministic admission control algorithm can admit.

In this work, call admission and transmis sion scheduling policies are studied for a TDMA system servicing Variable Bit Rate (VBR) applications with distinct QoS requirements and traf fic characteristics. In this environment. packets which experience excess delays are dropped (due to delay violations) at the source. In addition, packets are dropped at the receiver due to channel induced errors (interference) in the wireless link. The focus of the research is to determine the region of achievable QoS vectors for heterogeneous VBR applications in this shared resource environment and study the impact that channel quality has on the achievable performance. The region of achievable QoS vectors is central to the call admission problem and in this work, it is used to identify a class of scheduling policies capable of delivering any achievable performance.

In Software as a Service (SaaS)cloud marketplace, several functionally equivalent services tend to be available with different Quality of Service (QoS)values. For processing end-users multi-dimensional QoS and functional requirements, the application engineers are required to choose suitable services and optimize the service composition plans for each category of users. However, existing approaches for dynamic services composition tend to support execution plans that search for service provisions of equivalent functionalities with varying QoS or cost constraints to meet the tenants' QoS requirements or to dynamically respond to changes in QoS. These approaches tend to ignore the fact that multi-tenant execution plans need to provide variant execution plans, each offering a customized plan for a given tenant with its functionality, QoS and cost requirements. Henceforth, the dynamic selection and composition of multi-tenant service composition is a NP-hard dynamic multiobjective optimization problem. To address these challenges, we propose a novel multi-tenant middleware for dynamic service composition in the SaaS cloud. In particular, we present new encoding representation and fitness functions that model the service selection and composition as an evolutionary search. We incorporate our approach with two Multi-Objective Evolutionary Algorithms (MOEA), i.e., MOEA/D-STM and NSGA-II, to perform a comparative study. The experiment results show that the MOEA/D-STM outperforms NSGA-II in terms of quality of solutions and computation time.

Higher-speed passive optical networks (i.e., ITU-T 50G PONs) are envisioned to support various time-sensitive services with diverse quality of service (QoS) requirements (e.g., latency and jitter). To achieve this goal, higher-speed PON introduces multiple queues in each transmission container (T-CONT) so that each queue can carry a type of time-sensitive traffic. However, in the existing dynamic bandwidth allocation (DBA) schemes, the DBA engine in the optical line terminal (OLT) allocates bandwidth to four types of T-CONTs based on their buffer occupancies and priorities without considering queue status (e.g., the amount of data frames in queues) and services’ QoS requirements. To support multiple services belonging to the same T-CONT, the traffic scheduler in each optical network unit (ONU) further assigns the bandwidth of T-CONTs to their associated queues by using priority-based scheduling strategies. In this way, the bandwidth is allocated to queues by the DBA engine and traffic scheduler independently, which cannot guarantee network performance and meet the stringent QoS requirements of time-sensitive services. To solve this problem, we propose a DBA mechanism based on flexible queue management (FQM) to enable direct allocation of bandwidth to the queues under their QoS requirements. The proposed FQM mechanism enables the DBA engine to obtain the arrival time and QoS requirements of data frames in different queues as well as queue status based on the existing report/grant mechanism. By using these parameters, the required bandwidth for each queue in the next polling cycle can be calculated. Then, the DBA engine allocates bandwidth to these queues according to their bandwidth requests and priorities periodically. Simulation results show that the proposed scheme outperforms two benchmarks in the aspects of meeting time-sensitive services’ diverse QoS requirements, even when the traffic load is high.

Fuzzy-based dynamic bandwidth allocation for heterogeneous sources in ATM networks

Next generation wireless cellular networks aim at supporting Wireless Multimedia Services (WMSs) with different classes of traffic characterised by diverse Quality of Service (QoS) and bandwidth requirements. They will use micro/pico cellular architectures in order to provide higher capacity. However, small-size cells increase the handoff rate drastically. As a result, it is a challenge to provide stable QoS in these networks. This paper introduces a novel QoS Adaptive Call Admission Control (QoS-AdCAC) framework for next generation broadband wireless cellular networks supporting WMSs with different classes of traffic and diverse bandwidth requirements. In this work, each base station locally, independently of other Base Stations (BSs) in the network, differentiates between new and handoff calls for each class of traffic by assigning a threshold to each class according to its QoS requirements. The threshold values change dynamically in order to respond to the varying traffic conditions. The main feature of the proposed framework is its ability to simultaneously achieve several design goals, which makes it suitable for real time execution. Simulation results show the strength of our proposed framework.

Real time multimedia applications have diverse Quality of Service (QoS) requirements. Traditional routing algorithms are not adequate to handle the QoS requirements of these applications. Therefore, designing routing algorithms that optimizes multiple QoS requirements is one of the major issues in High-Speed Networks (HSN). QoS Routing is defined as finding paths satisfying multiple QoS constraints. It is a Multi-Constrained Path (MCP) Problem which is NP-complete and cannot be solved in polynomial time. Various heuristics and approximation algorithms have been proposed to solve multi-constrained QoS routing problem. In this paper we will discuss various QoS routing issues followed by review of some important heuristic algorithms developed to solve multi-constrained QoS routing problems.

3GPP LTE networks can provide a higher capacity by adopting advanced physical layer techniques and serve users with different Quality of Service (QoS) requirements. However, unbalanced user distributions and strong inter-cell interference (ICI) still deteriorate network performances severely. Since fractional frequency reuse (FFR) technique is recommended to mitigate ICI, we investigate the load balancing problem in a 3GPP LTE multi-cell FFR network with heterogenous services in this paper. Firstly we formulate a multi-objective optimization problem, whose objectives are intra- and inter-cell load balancing index for users with QoS requirements and total utility function for users without QoS requirements. Then we analyze the complexity of the problem and propose a practical algorithm which includes QoS aware intra- and inter-cell handover and call admission control. Extensive simulations are conducted, the results show that our algorithm can lead to significantly better performances, i.e., a lower new call blocking rate for users with QoS requirements, a larger utility for users without QoS requirements at the cost of a bit degradation of total throughput.

We consider the downlink of a cellular system in which the base station employs multiple transmit antennas, each receiver has a single antenna, and the users specify certain quality of service (QoS) requirements. We study the design of robust broadcasting schemes that minimize the transmission power necessary to guarantee that the QoS requirements are satisfied for all channels within bounded uncertainty regions around the transmitter's estimate of each user's channel. Each user's QoS requirement is formulated as a constraint on the mean square error (MSE) in its received signal, and we show that these MSE constraints imply constraints on the received signal-to-interference-plus-noise ratio. Using the MSE constraints, we present a unified approach to the design of linear and nonlinear transceivers with QoS requirements that must be satisfied in the presence of bounded channel uncertainty. The proposed designs overcome the limitations of existing approaches that provide conservative designs or are only applicable to the case of linear precoding. Furthermore, we provide computationally efficient design formulations for a rather general model of bounded channel uncertainty that subsumes many natural choices for the uncertainty region. We also consider the problem of the robust counterpart to precoding schemes that maximize the fidelity of the weakest user's signal subject to a power constraint. For this problem, we provide quasi-convex formulations, for both linear and nonlinear transceivers, that can be efficiently solved using a one-dimensional bisection search. Our numerical results demonstrate that in the presence of bounded uncertainty in the transmitter's knowledge of users' channels, the proposed designs provide guarantees for a larger range of QoS requirements than the existing approaches that are based on bounded channel uncertainty models and require less transmission power to provide these guarantees.

In this paper we present a concept for providing QoS to multicast in structured P2P networks. We show on the example of Scribe / Pastry how to enforce QoS aware tree construction in a structured P2P network. We achieve this by modifying the ID assignment method of Pastry based on the QoS requirements of peers. As a result, the multicast tree holds the QoS (bandwidth) requirements on each of its end-to-end paths. We have evaluated the proposed concept by comparing default random Pastry ID assignment with our proposed method. The results of the evaluation show that using our method all end- to-end paths in the multicast tree fullfill the bandwidth QoS requirements, which is usually not the case for default Pastry. I. INTRODUCTION In this paper we present a concept to enable Quality of Service (QoS) for multicast in the structured Peer-to-Peer (P2P) network Pastry (1) and the Application Level Multicast (ALM) infrastructure Scribe (2) running on-top of Pastry. This is achieved by replacing the random ID assignment of Pastry with a QoS requirements aware mechanism. We use this concept to enable QoS for IP Multicast over ALM in the European project called EuQoS (3), which aims to support end-to-end QoS over heterogeneous networks. EuQoS only supports unicast QoS between end-systems on the network level. The remainder of the paper is structured as follows: In Section II we motivate the need for QoS enabled multicast Overlay Networks. In the same Section we present the use of such a network to provide QoS enabled IP Multicast services to end-systems in the EuQoS project. In Section III we present the ALM infrastructure Scribe and the P2P routing substrate Pastry. We present our proposal for modifying the Scribe / Pastry ID assignment to enforce the construction of QoS aware multicast trees in Section IV. We evaluate the QoS improve- ments by comparing default Scribe / Pastry ID assignment with our modifications in Section V. An outlook of future considerations and improvements can be found in Section VI. Finally, Section VII concludes this paper.

Strategic users in a wireless network cannot be assumed to follow the network algorithms blindly. Moreover, some of these users aim to use their knowledge about network algorithms to maliciously gain more resources and also to create interference to other users. We consider a general model of Multiple Access Channel (MAC) without successive interference cancellation (SIC) under Quality of Service (QoS) requirement of each user where malicious behavior exists. We model the heterogeneous behavior of users, which ranges from altruistic to selfish and then to malicious, within the analytical framework of game theory. To ensure the QoS requirements with efficient resource allocation, the noncooperative game in normal form is formulated and the Nash Equilibrium (NE) power allocation is derived in closed form. The effects of malicious behavior in network resource allocation mechanisms such as auctions and pricing schemes are studied. We consider firstly the problem of net utility maximization and then individual user QoS requirement satisfaction. We show that the well-known Vicrey-Clarke-Groves (VCG) mechanism loses its efficiency property in the presence of malicious users, which motivates the need to quantify the effect of malicious behavior. Then, the Price of Malice of the VCG mechanism and of some other network mechanisms are derived. Differentiated pricing as a method to counter adversarial behaviors is discussed. Next, we consider power allocation in wireless networks subject to QoS requirements of the users. Given the designed individual prices, the best response (BR) power converges to the unique NE power allocation rapidly, where the QoS requirement of each transmitter is satisfied. The impact of the malicious behavior on other users with QoS requirements is analyzed and the punishment prices are designed. We show that in the proposed noncooperative power allocation game, the user misbehavior is predicted, detected and prevented. As a result, all rate requirements in the capacity region of the general MAC are achieved at the NE point. Next we consider a scenario, in which a mechanism designer and legitimate users gather probabilistic information about the presence of malicious users by observing the network over a long time period and modify their actions accordingly. We analyze Bayesian mechanisms, both pricing schemes and auctions, and obtain the Bayesian Nash Equilibrium (BNE) points. The BNE points provide conditions indicating when the uncertainty about their nature (type) is better for regular users. Finally, we extend Bayesian pricing mechanisms to wireless networks subject to QoS requirements of the users.

For a long time Wi-Fi has lacked methods for reliable multicast. A great step towards solving this problem has been made with release of the IEEE 802.11aa amendment, which introduces a number of new multicast methods. The amendment claims that reliability of the methods can be increased if transmission is performed in preliminarily reserved time intervals. If a transmitted flow imposes certain Quality of Service (QoS) requirements, parameters of such reservation-based multicast need to be appropriately adjusted to satisfy QoS at all receivers. In the paper, we consider QoS-aware multicasting of a variable bit rate (VBR) flow by means of periodic channel reservations. The core contribution of the paper is a generalized mathematical model which can be used to analyze efficiency of any of the standardized multicast methods. Particularly, the model can be used to find such transmission parameters, which guarantee that QoS requirements are satisfied at all receivers at the minimal amount of the reserved channel time.

The next generation networks are expected to provide heterogeneous services with higher data rates and diverse quality of service (QoS) requirements. For the major challenges we are confronted with nowadays, this paper establishes cross-layer architecture among application (AP) layer, media access control (MAC) layer and physical (PHY) layer, upon which an integrated radio resource management (RRM) strategy is proposed to explore the mechanisms of resource management. We design utility functions to characterize the satisfactory level of users subject to system resource constraints, according to their types of service and corresponding QoS requirements. Simulation results show that this design of integrated RRM strategy on cross-layer architecture achieves much better performances on resource use and QoS provision.