Deterministic Quality Of Service Guarantees Research Articles

QoS-aware MAC protocols for wireless sensor networks: A survey

The adoption of wireless sensor networks by applications that require complex operations, ranging from health care to industrial monitoring, has brought forward a new challenge of fulfilling the quality of service (QoS) requirements of these applications. However, providing QoS support is a challenging issue due to highly resource constrained nature of sensor nodes, unreliable wireless links and harsh operation environments. In this paper, we focus on the QoS support at the MAC layer which forms the basis of communication stack and has the ability to tune key QoS-specific parameters, such as duty cycle of the sensor devices. We explore QoS challenges and perspectives for wireless sensor networks, survey the QoS mechanisms and classify the state of the art QoS-aware MAC protocols together with discussing their advantages and disadvantages. According to this survey, we observe that instead of providing deterministic QoS guarantees, majority of the protocols follow a service differentiation approach by classifying the data packets according to their type (or classes) and packets from different classes are treated according to their requirements by tuning the associated network parameters at the MAC layer. Design tradeoffs and open research issues are also investigated to point out the further possible research directions in the field of QoS provisioning in wireless sensor networks at the MAC layer.

On delay constrained CAC scheme and scheduling policy for CBR traffic in IEEE 802.11e wireless LANs

AbstractCBR (constant bit rate) traffic is expected to be an important traffic source in wireless networks. Such sources usually have stringent jitter or delay requirements and in many cases they should be delivered exactly as they were generated. In this paper, we propose a strictly guaranteed QoS (quality‐of‐service) provisioning CAC (call admission control) scheme with a polling‐based scheduling policy for CBR traffic in IEEE 802.11e wireless LANs. Under such a scheme, the proposed transmit‐permission policy for HCCA (HCF controlled channel access) method can forecast the maximum suffered delay for each packet and derive sufficient conditions so that all the CBR sources satisfy their time constraints to provide deterministic QoS guarantees. A simple analytical model is carried out to estimate the average queueing delay of the proposed scheme. In addition to theoretical analysis, simulations are conducted to validate its promising performance. Our simulation results show that the proposed scheme maintains a high throughput with respect to the whole range of system load. Copyright © 2009 John Wiley & Sons, Ltd.

Delay constrained uplink scheduling policy for rtPS/ertPS service in IEEE 802.16e BWA systems

AbstractWiMAX is a promising broadband wireless networking technology and is expected to take the place of broadband access solutions such as DSL and cable. Owing to its superior support in mobility, it is expected to provide integrated voice and data service to realize broadband mobile computing. In order to reach better quality‐of‐service (QoS) requirements for real‐time applications, the IEEE 802.16e standard defines five different services among traffic categories with different multimedia requirements. However, the problem of choosing the right set of medium access control parameters and packet scheduling policy to provide strict QoS guaranteed in IEEE 802.16e Broadband Wireless Access (BWA) systems remains unsolved and left as an open issue. In this paper, we propose a novel polling‐based uplink packet scheduling policy for real‐time Polling Service and extended real‐time Polling Service (rtPS/ertPS) traffic to support real‐time applications, with strict delay requirements, such as variable bit rate (VBR) traffic in IEEE 802.16e BWA systems. The proposed transmit‐permission policy can derive sufficient conditions such that all the rtPS/ertPS sources satisfy their time constraints to provide deterministic QoS guarantees. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design provides a good quality performance in the IEEE 802.16e BWA systems. Copyright © 2008 John Wiley & Sons, Ltd.

FP/FIFO scheduling: coexistence of deterministic and probabilistic QoS guarantees

Distributed Computing and Networking In this paper, we focus on applications having quantitative QoS (Quality of Service) requirements on their end-to-end response time (or jitter). We propose a solution allowing the coexistence of two types of quantitative QoS garantees, deterministic and probabilistic, while providing a high resource utilization. Our solution combines the advantages of the deterministic approach and the probabilistic one. The deterministic approach is based on a worst case analysis. The probabilistic approach uses a mathematical model to obtain the probability that the response time exceeds a given value. We assume that flows are scheduled according to non-preemptive FP/FIFO. The packet with the highest fixed priority is scheduled first. If two packets share the same priority, the packet arrived first is scheduled first. We make no particular assumption concerning the flow priority and the nature of the QoS guarantee requested by the flow. An admission control derived from these results is then proposed, allowing each flow to receive a quantitative QoS guarantee adapted to its QoS requirements. An example illustrates the merits of the coexistence of deterministic and probabilistic QoS guarantees.

Multiservice provisioning mechanism with service curves assurance for per-class scheduling delay guarantees

Class-based traffic treatment frameworks, such as differentiated service (DiffServ), have been proposed to solve the scalability problem of flow-based approach for quality of service (QoS) provisioning. While these frameworks provide service differentiation according to traffic classes, the provision of QoS guarantee for individual flows, within a class, remains a challenging problem. In the paper, the authors present a novel multiservices mechanism, which is able to provide service curves assurance for per-flow deterministic delay guarantees. The core component of this mechanism is a new packet scheduling algorithm, called flow-state-dependent packet scheduling (FDPS), to handle different flows within the same class to provide end-to-end scheduling delay bound guarantees. The mechanism is based on an analysis that guides the flow admission control operation for class-based queueing delay bound. Using the packets' flow-states, FDPS provides fine granularity packet service differentiation within each class. By means of this property, the proposed mechanism achieves per-flow end-to-end delay bound independent of the number of intermediate nodes along the path of the flow. Another notable feature is that it can be integrated into a DiffServ framework as an enhancement for deterministic QoS guarantees. The performance of this mechanism is mathematically analysed to demonstrate its enhancements and ns-2 simulation experiments are used to validate the analytical results.

Providing deterministic packet delays and packet losses in multimedia wireless networks

Abstract‘Anytime, anywhere’ communication, information access and processing are much cherished in modern societies because of their ability to bring flexibility, freedom and increased efficiency to individuals and organizations. Wireless communications, by providing ubiquitous and tetherless network connectivity to mobile users, are therefore bound to play a major role in the advancement of our society. Although initial proposals and implementations of wireless communications are generally focused on near‐term voice and electronic messaging applications, it is recognized that future wireless communications will have to evolve towards supporting a wider range of applications, including voice, video, data, images and connections to wired networks. This implies that future wireless networks must provide quality‐of‐service (QoS) guarantees to various multimedia applications in a wireless environment.Typical traffic in multimedia applications can be classified as either Constant‐Bit‐Rate (CBR) traffic or Variable‐Bit‐Rate (VBR) traffic. In particular, scheduling the transmission of VBR multimedia traffic streams in a wireless environment is very challenging and is still an open problem. In general, there are two ways to guarantee the QoS of VBR multimedia streams, either deterministically or statistically. In particular, most connection admission control (CAC) algorithms and medium access control (MAC) protocols that have been proposed for multimedia wireless networks only provide statistical, or soft, QoS guarantees.In this paper, we consider deterministic QoS guarantees in multimedia wireless networks. We propose a method for constructing a packet‐dropping mechanism that is based on a mathematical framework that determines how many packets can be dropped while the required QoS can still be preserved. This is achieved by employing: (1) An accurate traffic characterization of the VBR multimedia traffic streams; (2) A traffic regulator that can provide bounded packet loss and (3) A traffic scheduler that can provide bounded packet delay. The combination of traffic characterization, regulation and scheduling can provide bounded loss and delay deterministically. This is a distinction from traditional deterministic QoS schemes in which a 0% packet loss are always assumed with deterministically bounding the delay.We performed a set of performance evaluation experiments. The results will demonstrate that our proposed QoS guarantee schemes can significantly support more connections than a system, which does not allow any loss, at the same required QoS. Moreover, from our evaluation experiments, we found that the proposed algorithms are able to out‐perform scheduling algorithms adopted in state‐of‐the‐art wireless MAC protocols, for example Mobile Access Scheme Based on Contention and Reservation for ATM (MASCARA) when the worst‐case traffic is being considered. Copyright © 2002 John Wiley & Sons, Ltd.

Traffic engineering in a multipoint-to-point network

The need to guarantee quality-of-service (QoS) to multimedia applications leads to a tight integration between the routing and forwarding functions in the Internet. multiprotocol label switching tries to provide a global solution for this integration. In this context, multipoint-to-point (m2p) networks appear as a key architecture since they provide a cheaper way to connect edge nodes than point-to-point connections. M2p networks have been mainly studied for their load balancing ability. In this paper, we go a step further: we propose and evaluate a traffic management scheme that provides deterministic QoS guarantees for multimedia sources in an m2p network. We first derive an accurate upper bound on the end-to-end delay in an m2p architecture based on the concept of additivity. Broadly speaking, an m2p network is additive if the maximum end-to-end delay is equal to the sum of local maximum delays. We then introduce two admission control algorithms for additive networks: a centralized algorithm and a distributed algorithm and discuss their complexity and their scalability.

Provision of guaranteed services in broadband LEO satellite networks

The provision of guaranteed services in low earth orbit (LEO) satellite networks is rather complicated due to the mobility of satellites. Users may be handed-off from one spot beam to another and/or from one satellite to another frequently during the lifetime of their calls. Traffic on inter-satellite links (ISLs) incident on a particular satellite change as the user traffic served by the satellite changes due to satellite mobility. The variation of user traffic over the ISLs may cause violation of quality of service (QoS) requirements of ongoing connections. We propose a novel protocol which we call the predictive routing protocol (PRP), which exploits the deterministic nature of the LEO satellite topology to maximize the total number of users served by the system, while maintaining each user's QoS requirements. PRP predicts the traffic load on the ISLs up to a short time in the future by using the deterministic knowledge of the LEO satellite topology and user location information. PRP determines multiple paths for a particular connection that effectively help avoid possible future bottlenecks as predicted by estimated future traffic on the ISLs. The protocol is compared with other non-predictive routing protocols such as IP routing by simulations and it is shown that PRP can deliver deterministic QoS guarantees (such as delay or delay jitter), without over-reserving channel bandwidth. An admission control curve has also been obtained which may be used to limit the number of users in order to ensure that the desired QoS metrics may be guaranteed.

Providing per-session deterministic quality of service guarantees in cross-path packet switch

Recently, a quasi-static routing scheme called path switching was proposed for large-scale packet switch systems. The path-switched Clos network is called a cross-path switch. Cross-path switch is capable of supporting multirate and multicast traffic. In this paper, we develop a general framework for it to handle multimedia traffic. We obtain upper bounds on the delay and backlog at the cross-path switch on a per-session basis, wherein no packet lost or delay bound violation is allowed. Our results show that these bounds much depend on the way of token assignment at the central stage. To understand such dependence, we quantify the effect of the token assignment on the switch performance. From these results, we design an effective token assignment scheme to achieve better performance guarantees in the switch. We show that cross-path switch with such token assignments always provides near-optimal performance guarantees to each data session.

Deterministic loss ratio quality of service guarantees for high speed networks

Current research for the provision of deterministic quality of service guarantees in both IP networks and high speed networks involve only bounded delay guarantees, In this letter, loss ratio is considered. We propose constraints on the service function in order to provide not only deterministic bounded loss ratio under a given buffer capacity but also bounded delay. Network operation can be easily managed by existing service-function-based scheduling algorithms.

On the effects of smoothing for deterministic QoS

In order for a network to provide end-to-end guarantees on quality of service (QoS), it must allocate its resources according to the traffic characteristics and performance requirements of its clients. However, the burstiness of typical variable bit rate traffic streams makes it difficult to provide the QoS guarantees that the network's clients require and simultaneously make efficient use of network resources. In this paper, we investigate the impact that smoothing traffic at the network's edge has on both the client's QoS and on the network's utilization. Considering the case of end-to-end deterministic QoS guarantees, we explore the analytical foundations of smoothing and identify the scenarios in which smoothing is beneficial to the network or its clients. Moreover, we quantify the potential benefits of smoothing with a set of experiments based on traces of MPEG-compressed video in heterogeneous multi-hop networking environments.

Quality of service guarantees in virtual circuit switched networks

We review some recent results regarding the problem of providing deterministic quality of service guarantees in slot-based virtual circuit switched networks. The concept of a service curve is used to partially characterize the service that virtual circuit connections receive. We find that service curves provide a convenient framework for managing the allocation of performance guarantees. In particular, bounds on end-to-end performance measures can be simply obtained in terms of service curves and burstiness constraints on arriving traffic. Service curves can be allocated to the connections, and we consider scheduling algorithms that can support the allocated service curves. Such an approach provides the required degree of isolation between the connections in order to support performance guarantees, without precluding statistical multiplexing. Finally, we examine the problem of enforcing burstiness constraints in slot-based networks. >