Search

Recent developments and widespread in wireless sensor network have led to many routing protocols, many of these protocols consider the efficiency of energy as the ultimate factor to maximize the WSN lifetime. The quality of Service (QoS) requirements for different applications of wireless sensor networks has posed additional challenges. Imaging and data transmission needs both QoS aware routing and energy to ensure the efficient use of sensors. In this paper, we propose an Efficient, Energy-Aware, Least Cost, (ECQSR) quality of service routing protocol for sensor networks which can run efficiently with best-effort traffic processing. The protocol aims to maximize the lifetime of the network out of balancing energy consumption across multiple nodes, by using the concept of service differentiation, finding lower cost by finding the shortest path using nearest neighbor algorithm (NN), also put certain constraints on the delay of the path for real-time data from where link cost that captures energy nodes reserve, energy of the transmission, error rate and other parameters. The results show that the proposed protocol improves the network lifetime and low power consumption. [ABSTRACT FROM AUTHOR]

eHealth applications have become essential in everyday life healthcare especially for elderly and sick individuals. To provide efficiency to such applications, many standards emerged for WBANs. However, WBANs standards showed their limits in terms of QoS and priorities differentiation depending on applications need. In this paper, we investigate IEEE 802.15.6 MAC performance efficiency and we define TA-802.15.6, an enhanced IEEE 802.15.6 CSMA/CA channel access mechanism. We aim to differentiate all IEEE 802.15.6 priorities traffics and to improve IEEE 802.15.6 based networks performances. Our main contribution is the enhancement of IEEE 802.15.6 CSMA/CA retransmission and packet drop processes. We also defined a new algorithm for dynamic backoff bounds assignment according to IEEE 802.15.6 priorities and to the network traffic state. We make an analytical evaluation through a new 4D Markov chain and by simulation based on Castalia. Results validate that the enhanced IEEE 802.15.6 CSMA/CA version provides a better service differentiation through accentuating priority differentiation and a better QoS in terms of reliability, throughput and energy consumption. [ABSTRACT FROM AUTHOR]

The spectrum fragmentation problem remains to be an open issue in elastic optical networks. In addition, the quality of service cannot be ignored during the transmission process. In this paper, we propose a novel spectrum defragmentation strategy considering the service differentiation, named SDSD, to improve the network performance in terms of the spectrum resources utilization, blocking probability (BP), and the set-up time for the serving connections. The presented results show that the proposed scheme can allocate the spectrum resources efficiently while decreasing the BP and connection set-up time. Moreover, the low grade services will be migrated preferentially during the phase of spectrum defragmentation, decreasing the number of migration. [ABSTRACT FROM AUTHOR]

Optical Code Division Multiple Access (OCDMA) provides increased security communications with large dedicated bandwidth to end users and simplified network control. We analyse the call-level performance of an OCDMA Passive Optical Network (PON) configuration, which accommodates multiple service-classes with finite traffic source population. The considered user activity is in accordance with the bursty nature of traffic, so that calls may alternate between active (steady transmission of a burst) and passive states (no transmission at all). Parameters related to multiple access interference, additive noise, user activity and number of traffic sources are incorporated to our analysis, which is based on a two-dimensional Markov chain. An approximate recursive formula is derived for efficient calculation of call blocking probability. Furthermore, we determine the burst blocking probability; burst blocking occurs when a burst delays its returning from passive to active state. The accuracy of the model is completely satisfactory and is verified through simulation. Moreover, we reveal the consistency and necessity of the proposed model. [ABSTRACT FROM AUTHOR]

Abstract: In critical scenarios nodes switch from low data rate of transmission mode to high data rate. Such scenarios are event driven and traffic is highly dynamic in nature. Latency and reliability issues with Quality of Service (QoS) for such applications in IEEE 802.15.4 have been an issue. The earlier schemes did address them but high data rates and channel error rates resulted in increase in contention for GTS request packets and increased data packet drop rate. In our work, we employed a mechanism to deal with isuues arising out of additional contention caused by prioritized nodes in CAP. We present an enhanced MAC scheme that incorporates two-level service differentiation through Contention Window Differentiation (CWD) and dynamic p-persistent CSMA, for mitigating the issues like lower transmission delays and higher success probability to time-critical messages in high channel error conditions. We evaluate our proposed scheme for varying channel and traffic-load conditions by simulation using Omnet+ + .The results show that performance in terms of the mentioned issues has improved significantly. Further, the energy decline rate analysis have been done for varying traffic arrival rates and compared with the original IEEE 802.15.4 and found that our scheme has less energy decline rate thus increased network lifetime. [Copyright &y& Elsevier]

IEEE 802.15.4 employs carrier sense multiple access with collision avoidance (CSMA/CA), which is known to have difficulty for supporting quality of service (QoS). In this paper, a new priority scheme called priority jamming (P J) is proposed for service differentiation for IEEE 802.15.4. The main idea of the proposed scheme is deferring the low priority packet transmission for the high priority packet. Clear channel assessment of IEEE 802.15.4 is modified to support the proposed PJ. The efficiency of the proposed scheme is validated by comparing the delay, throughput, and energy-per-bit with those of standard CSMA/CA. Simulations results showed that PJ improves the delay and throughput simultaneously while maintaining marginal difference in energy efficiency. [ABSTRACT FROM AUTHOR]

In this paper, we first survey cross-layer architectures for Wireless Sensor Networks (WSNs) and Wireless Multimedia Sensor Networks (WMSNs). Afterwards, we propose a novel cross-layer architecture for QoS provisioning in clustered and multi-hop based WMSNs. The proposed architecture provides support for multiple network-based applications on a single sensor node. For supporting multiple applications on a single node, an area in memory is reserved where each application can store its network protocols settings. Furthermore, the proposed cross-layer architecture supports heterogeneous flows by classifying WMSN traffic into six traffic classes. The architecture incorporates a service differentiation module for QoS provisioning in WMSNs. The service differentiation module defines the forwarding behavior corresponding to each traffic class. The forwarding behavior is primarily determined by the priority of the traffic class, moreover the service differentiation module allocates bandwidth to each traffic class with goals to maximize network utilization and avoid starvation of low priority flows. The proposal incorporates the congestion detection and control algorithm. Upon detection of congestion, the congested node makes an estimate of the data rate that should be used by the node itself and its one-hop away upstream nodes. While estimating the data rate, the congested node considers the characteristics of different traffic classes along with their total bandwidth usage. The architecture uses a shared database to enable cross-layer interactions. Application's network protocol settings and the interaction with the shared database is done through a cross-layer optimization middleware. [ABSTRACT FROM AUTHOR]

In this paper, we depart from our previously proposed Non-Congestive Queuing (NCQ) mechanism and propose a new scheduling discipline that allows for efficient interoperation of dedicated systems (such as sensor and voice networks) with the Internet. More precisely, our approach provides delay guarantees to applications that do not contribute noticeably to congestion because of their tiny packet sizes and low transmission rates. In addition, our approach uses a second level of prioritization that conditionally favors, in terms of delay, applications with slightly longer packets as well. Based on the NCQ concept, Non-Congestive Queuing Plus (NCQ+) promotes applications that require comparatively small service times, as long as their total service times cause insignificant delays to other packets in the queue. Therefore, we prioritize packets, and in turn corresponding flows, according to their impact on total delay. We evaluate NCQ+ using ns-2-based experiments. Results show that whenever prioritization buffer resources are sufficient, NCQ+ can provide non-detectable delays to sensor applications and conditionally improve the performance of VoIP applications, while maintaining the impact on the performance of the other flows insignificant. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a novel prioritization mechanism for random access strategies in cellular networks is proposed. The proposed prioritized random access strategy sets different retransmission probabilities to users, depending on their priorities. First, a mathematical analysis method for simultaneously evaluating throughput and access delay, considering an infinite population model and different retransmission policies, is developed. Most of the previous related research has been done, considering both finite population and saturation conditions where all the nodes in the system always have a packet ready to be transmitted, and the transmission queue of each station is assumed to be always nonempty. This assumption is a good approximation for a local area network working at full capacity. However, in a cellular system, the assumptions of a finite population and every node in a cell always having a packet to transmit are not very realistic. Here, the analytical results consider a Poisson arrival process-which is more suitable for the traffic model in a cellular system-for the users in the cells. Then, considering slotted ALOHA as a random access strategy and the developed analysis method, the case where two different types of service exist (low- and high-priority users) is mathematically analyzed. With the proposed prioritized random access strategy, the average access delay achieved for the high priority users is always lower than that for the low-priority users. Additionally, a mathematical expression for the throughput is derived with and without service differentiation. Finally, two approaches for finding the optimum retransmission probabilities are developed; in the first approach, the number of. backlogged packets is required, whereas a simpler and efficient alternative method requires only the knowledge of the mean new packet arrival rate. For the performance analysis, four of the most common backoff algorithms are considered: 1) Uniform (UB); 2) Binary Exponential (BEB); 3) Negative Exponential (XB); and 4) Geometric (GB). [ABSTRACT FROM AUTHOR]

We propose a novel payment-based incentive scheme for peer-to-peer (P2P) live media streaming. Using this approach, peers earn points by forwarding data to others. The data streaming is divided into fixed-length periods; during each of these periods, peers compete with each other for good parents (data suppliers) for the next period in a first-price-auction-like procedure using their points. We design a distributed algorithm to regulate peer competitions and consider various individual strategies for parent selection from a game-theoretic perspective. We then discuss possible strategies that can be used to maximize a peer's expected media quality by planning different bids for its substreams. Finally, in order to encourage off-session users to remain online and continue contributing to the network, we develop an optimal data forwarding strategy that allows peers to accumulate points that can be used in future services. Simulation results show that the proposed methods effectively differentiate the media qualities received by peers making different contributions (which originate from, for example, different forwarding bandwidths or servicing times) and at the same time maintain high overall system performance. [ABSTRACT FROM AUTHOR]

Abstract: In sensor networks, data packets transmitted by different devices in home networking and industrial applications maintain different levels of importance. In this paper, we propose two mechanisms for IEEE 802.15.4 sensor networks to provide multi-level differentiated services which are required by each and every device. Mathematical model based on the discrete-time Markov chain is presented and is analyzed to measure the performance of the proposed mechanisms. Numerical results show the effects of the variation of contention window size and backoff exponent for service differentiation on 802.15.4 sensor networks. From the results, we derive that contention window size is more affective than backoff exponent on the saturation throughput while backoff exponent is more affective than contention window size on the average delay of every device. Simulation results are given to verify the accuracy of the numerical model. [Copyright &y& Elsevier]

A substantial portion of the emerging wireless data service consists of non-real-time applications such as content download. The existing mechanisms based on per-packet performance guarantees used mainly for voice and streaming media do not suffice for the elastic nature of non-real-time traffic. For a non-real-time user data services, the key performance measure of interest is the total download time. In this paper, we propose a novel scheduling framework for wireless content service. Specifically, we present a two-layer scheduling architecture that combines content-aware scheduling with opportunistic scheduling. In terms of content- awareness, the proposed scheduling policy provides guarantees on the download time of content. In the second stage, the instantaneous channel conditions of different users are exploited in an opportunistic manner so as to maximize the throughput of the system. We define service differentiation in two modes—differential and guaranteed—and provide polynomial time algorithms for both that manipulate the stretch ratio but within allowable limits. Extensive simulations are conducted that verify the efficiency of the proposed schemes and provide insights into the behavior of the scheduling algorithms for non-real-time data. [ABSTRACT FROM AUTHOR]

To provide ubiquitous access to the proliferating rich media on the Internet, scalable streaming servers must be able to provide differentiated services to various client requests. Recent advances of transcoding technology make network-I/O bandwidth usages at the server communication ports controllable by request schedulers on the fly. In this article, we propose a transcoding-enabled bandwidth allocation scheme for service differentiation on streaming servers. It aims to deliver high bit rate streams to high priority request classes without overcompromising low priority request classes. We investigate the problem of providing differentiated streaming services at application level in two aspects: stream bandwidth allocation and request scheduling. We formulate the bandwidth allocation problem as an optimization of a harmonic utility function of the stream quality factors and derive the optimal streaming bit rates for requests of different classes under various server load conditions. We prove that the optimal allocation, referred to as harmonic proportional allocation, not only maximizes the system utility function, but also guarantees proportional fair sharing between classes with different prespecified differentiation weights. We evaluate the allocation scheme, in combination with two popular request scheduling approaches, via extensive simulations and compare it with an absolute differentiation strategy and a proportional- share strategy tailored from relative differentiation in networking. Simulation results show that the harmonic proportional allocation scheme can meet the objective of relative differentiation in both short and long timescales and greatly enhance the service availability and maintain low queueing delay when the streaming system is highly loaded. [ABSTRACT FROM AUTHOR]

Efficient network provisioning mechanisms that support service differentiation are essential to the realization of the Differentiated Services (DiffServ) Internet. Building on our prior work on edge provisioning, we propose a set of efficient dynamic node and core provisioning algorithms for interior nodes and core networks, respectively. The node provisioning algorithm prevents transient violations of service level agreements (SLA) by predicting the onset of service level violations based on a multiclass virtual queue measurement technique, and by automatically adjusting the service weights of weighted fair queueing schedulers at core routers. Persistent service level violations are reported to the core provisioning algorithm, which dimensions traffic aggregates at the network ingress edge. The core provisioning algorithm is designed to address the difficult problem of provisioning DiffServ traffic aggregates (i.e., rate-control can only be exerted at the root of any traffic distribution tree) by taking into account fairness issues not only across different traffic aggregates but also within the same aggregate whose packets take different routes through a core IP network. We demonstrate through analysis and simulation that the proposed dynamic provisioning model is superior to static provisioning for DiffServ in providing quantitative delay bounds with differentiated loss across per-aggregate service classes under persistent congestion and device failure conditions when observed in core networks. [ABSTRACT FROM AUTHOR]

The successful operation of emerging public wireless local-area networks requires flexible network mechanisms that can support differentiated or tiered services for a variety of applications such as bursty transactional web applications, as well as reservation demanding voice and video applications. Congestion pricing has been proposed as one promising solution to traffic control because it accurately models the cost that each user's traffic imposes on network congestion points. The underlying assumption of congestion pricing is that users will respond to a monetary-based price signal to maximize their own utility. We observe, however, that monetary service charge is largely a business concern and not a traffic control concern because operators and users prefer simple, predictable, and stable service charges such as flat-rate or block-rate charging. Therefore, we argue, that traffic control techniques such as congestion pricing should be decoupled from monetary service charges. Under such a new regime, however, a user's response to a nonmonetary price signal would be quite different from utility maximization, and without the appropriate incentives for users to cooperate such a regime would lead to the "tragedy of the commons" phenomenon, undermining any future differentiated service offerings by wireless Internet service providers. To address this problem, we propose wireless incentive engineering mechanisms for mobile devices (MDs) and access points (APs) that provide incentives for mobile users to cooperatively use different classes of services without relying on monetary service charging. Wireless incentive engineering possesses a number of beneficial properties including minimizing the algorithmic and protocol overhead on MDs and APs, Nash bargaining fairness, and incentive compatibility for mobile users promoting the truthful selection of service class and bandwidth declaration. We use analysis, simulation, and experimental results from a wireless testbed... [ABSTRACT FROM AUTHOR]

In this paper, the multiple fractional channel reservation (MFCR) strategy for service differentiation is proposed. MFCR overcomes the "integer nature" of traditional channel reservation schemes (also referred as guard channel, trunk reservation, or cutoff priority) that precludes them to achieve maximum system capacity in single- and multiservice environments. Contrary to the rest of channel reservation schemes previously proposed in the literature on the topic, MFCR reserves, on average, real numbers of channels to prioritize new and/or handoff calls in multiple service environments. Given a set of requirements on new call blocking and forced termination probabilities for each service type, MFCR maximizes system capacity while meeting the Quality of Service (QoS) constraints in multiservice mobile cellular networks. It finely controls the communication service quality, by varying the average numbers of reserved channels by a fraction of one. Determining the right amount of resources (cutoff threshold or number of reserved channels) to prioritize each call type and to satisfy all QoS constraints in multiservice environments, however, is a difficult task. Selecting the optimal prioritization order is not an easy process either, as it is affected by QoS constraints, system characteristics, and resource sharing. Thus, an heuristic algorithm to determine the optimum numbers of reserved (resources) channels to achieve maximum system capacity when using the MFCR is also proposed. To our knowledge, the capacity optimization problem considering individual QoS constraints had only been addressed in single service environments. Also, a comprehensive survey on channel reservation strategies proposed in the literature has been included. [ABSTRACT FROM AUTHOR]

The increase in network applications diversity and different service quality requirements lead to service differentiation, making it more important than ever. In Wide Area Network (WAN), the non-responsive Long-Term Fast (LTF) flows are the main contributors to network congestion. Therefore, detecting and suppressing non-responsive LTF flows represent one of the key points for providing data transmission with controllable delay and service differentiation. However, the existing single-queue management algorithms are designed to serve only a small number of applications with similar requirements (low latency, high throughput, etc.). The lack of mechanisms to distinguish different traffic makes it difficult to implement differentiated services. This paper proposes an active queue management scheme, namely, SQM-LRU, which realizes service differentiation based on Shadow Queue (SQ) and improved Least-Recently-Used (LRU) strategy. The algorithm consists of three essential components: First, the flow detection module is based on the SQ and improved LRU. This module is used to detect non-responsive LTF flows. Second, different flows will be put into corresponding high or low priority sub-queues depending on the flow detection results. Third, the dual-queue adopts CoDel and RED, respectively, to manage packets. SQM-LRU intends to satisfy the stringent delay requirements of responsive flow while maximizing the throughput of non-responsive LTF flow. Our simulation results show that SQM-LRU outperforms traditional solutions with significant improvement in flow detection and reduces the delay, jitter, and Flow Completion Time (FCT) of responsive flow. As a result, it reduced the FCT by up to 50% and attained 95% of the link utilization. Additionally, the low overhead and the operations incur O(1) cost per packet, making it practical for the real network. [ABSTRACT FROM AUTHOR]

The single best-effort service of the Internet struggles to accommodate divergent needs of different distributed applications. Numerous alternative network architectures have been proposed to offer diversified network services. These innovative solutions failed to gain wide deployment primarily due to economic and legacy issues rather than technical shortcomings. Our paper presents a new simple paradigm for network service differentiation that accounts explicitly for the multiplicity of Internet service providers and users as well as their economic interests in environments with partly deployed new services. Our key idea is to base the service differentiation on performance itself, rather than price. We design RD (Rate-Delay) network services that give a user an opportunity to choose between a higher transmission rate or low queuing delay at a congested network link. To support the two services, an RD router maintains two queues per output link and achieves the intended rate-delay differentiation through simple link scheduling and dynamic buffer sizing. We evaluate the performance, deployment, and security properties of the RD network services in various network topologies and traffic scenarios including delay-sensitive VoIP (Voice over Internet Protocol) applications. [ABSTRACT FROM PUBLISHER]