A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> Abstract Recent technological advances have made it possible to havelarge wireless ad-hoc networks of small devices. The primepurpose of such sensor networks is to disseminate informationabout the environmentthey sense. We observethat informationprovidedmayhavedifferent levelsof importanceandarguethatthe sensor networks should be willing to spend more resourcesin disseminating packets carrying more important information.In this paper, weintroducethe conceptof servicedifferenti-ationasapplicabletosensornetworks,highlightitsfundamentaldifferences with normal data networks and deﬁne the relevantmetrics. Variousmechanismswhichmay provideservicescom-patible with the packet priority levels are proposed. We evalu-ate one of the proposedmethod , Adaptive Forwarding Scheme(AFS) and show that our scheme provides the desired levels ofservice. Keywords SensorNetworks,ServiceDifferentiation, AdaptiveForwardingScheme 1. Introduction Technologicaladvanceshavemade it feasible to havesmall de-vices with computation, communication and sensing capabili-ties [1, 2, 3]. These devices run on batteries and thus their ca-pabilities are limited by the available energy. A sensornetworkconsistingofalargenumberofsuchnodescanbeusefulinkeep-ing track of various activities in a givenregion. However, oper-ations performed in such a sensor network have to be energy-efﬁcient becauseof the energy constraints of its nodes.In a sensor network, sensors would sensesome data, pack-etize it and send the packet to a monitor node along a path con-sisting of multiple wireless hops. Researchers have come upwith schemes to provide the functionality required to performthese operations efﬁciently. For routing the data to the moni-tor node, schemeslike Directed Diffusion [4] and Power-awarerouting [5] have been proposed. Clustering schemes [6, 7, 8]group the nodesinto clusters for network management[7]. Lo-cation dissemination schemes [9, 10] provide the sensors withinformation about their locations. Simple and efﬁcient operat-ing system like tinyOS [3] have been designed for these smallnodes. All these works focus on cutting down on the energyrequirements of a sensor network, while providing the minimalfunctionality for the network to operate.We observe that in sensor networks different data packetsmight have different importance.For example, if a temperaturesensorinaforest,senses60Fonanormalspringday,thevalueis <s> BIB001 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> Recent advances in wireless technology have brought us closer to the vision of pervasive computing where sensors/actuators can be connected through a wireless network. Due to cost constraints and the dynamic nature of sensor networks, it is undesirable to assume the existence of base stations connected by a wired backbone. In this paper, we present a network architecture suitable for sensor networks along with a medium access control protocol based on earliest deadline first. <s> BIB002 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> We present an innovative MAC protocol (Q-MAC) that minimizes the energy consumption in multi-hop wireless sensor networks (WSNs) and provides quality of service (QoS) by differentiating network services based on priority levels. The priority levels reflect application priority and the state of system resources, namely residual energy and queue occupancies. The Q-MAC utilizes both intra-node and inter-node arbitration. The intra-node packet scheduling is a multiple queuing architecture with packet classification and weighted arbitration. We also introduce the power conservation MACAW (PC-MACAW) - a power-aware scheduling mechanism that, together with the loosely prioritized random access (LPRA) algorithm, govern the inter-node scheduling. Performance evaluation are conducted between Q-MAC and S-MAC with respect to two performance metrics: energy consumption and average latency. Simulation results indicate that the performance of the Q-MAC is comparable to that of the S-MAC in non-prioritized traffic scenarios; when packets with different priorities are present, Q-MAC supiors in average latency differentiation between the classes of service, while maintaining the same energy level as that of S-MAC <s> BIB003 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> This paper presents a new prioritized medium access control protocol (PSIFT) that improves the performance of event-driven wireless sensor networks by suppressing the redundant reports of sensor nodes in proximity. This suppression of similar reports results in low collision probability, shorter delay and accurate detection of events by the sink. PSIFT is a CSMA-based MAC protocol that provides traffic differentiation by varying the inter frame space and contention window size for each traffic class. We also introduce the new report suppression mechanism based on the broadcast nature of wireless transmission in PSIFT. This mechanism works very efficiently in large-scale, event-driven wireless sensor networks. Simulation results show that the new PSIFT MAC protocol can bring significant improvement in delay performance of the networks. When the sensing range grows up to transmission range, PSIFT can reduce the latency as much as three times in delivering reports as compared to the existing IEEE802.11 MAC protocol. <s> BIB004 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> Wireless sensor networks are very application specific and have to be developed according to the requirements of a particular problem. They are usually deployed in harsh and mobile environments, with tasks ranging from just collecting environment readings to highly crucial tasks like tracking an enemy vehicle. This means the sensor networks can monitor or sense a very wide range of parameters and tasks. However, all these measurements and events that are read by the sensors are never of equal importance. So we propose PR-MAC, which provides a scheme in which we prioritize the events that are being recognized. Our aim is to design a MAC layer protocol which would reduce the delay of transmitting high priority tasks or measurements. <s> BIB005 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> Rapid penetration of small, customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. While the need to minimize the energy consumption has driven significant researches in wireless sensor networks, offering some precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However, the emerging new applications like video surveillance, telemedicine and traffic monitoring needs transmission of wireless multimedia over sensor networks. Naturally, offering some better QoS for wireless multimedia over sensor networks raises significant challenges. The network needs to cope up with battery-constraints, while providing improved QoS (end-to-end delay and bandwidth requirement). This calls for a suitable sensory MAC protocol capable of achieving application-specific QoS. In this paper, we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modeling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols. <s> BIB006 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> Ultra-wideband (UWB) is a physical (PHY) layer technology that promises high transmission rates, as well as high resistance to noise and multipath effects. However, the impulse-based nature of UWB, coupled with its low transmission power, makes it difficult to enable efficient detection of the signals. Consequently, conventional carrier-sensing based MAC protocols cannot be used with a UWB PHY. In this paper, we propose SASW-CR - a slotted Aloha MAC protocol for UWB networks with sliding contention window and cooperative retransmissions, which provides QoS support without the use of carrier sensing. SASW-CR utilizes the slotted-Aloha technique to avoid carrier sensing and reduce packet collisions. In addition, it makes use of differentiated contention windows to provide varying classes of QoS for different traffic classes. A cooperative retransmission technique is also introduced to improve the overall traffic throughput and reduce end-to-end delay. The efficacy of our protocol is demonstrated through simulations. <s> BIB007 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> This paper introduces I-MAC, a new medium access control protocol for wireless sensor networks. I-MAC targets at improving both channel utilisation and energy efficiency while taking into account traffic load for each sensor node according to its role in the network. I-MAC reaches its objectives through prioritized and adaptive access to the channel. I-MAC performances obtained through simulations for different network topologies, scenarios and traffic loads show significant improvements in energy efficiency, channel utilization, loss ratio and delay compared to existing protocols. <s> BIB008 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Service Differentiation. <s> 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. <s> BIB009
Service differentiation differentiates and prioritizes the traffic carried on the network based on one or more criteria and forms several traffic classes BIB001 . In this way, MAC layer treats each of these traffic classes differently by managing the resource sharing among them and tries to fulfill the requirements imposed by their degree of importance. Service differentiation consists of two phases: (i) priority assignment and (ii) differentiation between priority levels. In general, priority assignment schemes are categorized into the following three levels. (i) Static Priority Assignment. Priority assignment is static if it never changes until the journey to destination, after once it is assigned. Static priority assignment depends on various network parameters like traffic class BIB006 BIB003 , source type BIB007 , and data delivery model BIB005 . (ii) Dynamic Priority Assignment. In this scheme, the packet priorities may vary until delivery. This variable assignment scheme is beneficial in terms of frequent topology changes. The criteria for this scheme are remaining hop count, traversed hop count BIB003 BIB004 , packet deadline BIB002 , and remaining energy and traffic load BIB003 BIB008 . (iii) Hybrid Priority Assignment. Unlike either static or dynamic, the good things in both schemes shall be merged together in hybrid priority assignment. However, balancing between static and dynamic priority schemes is to be done with utmost care to achieve better and reliable packet delivery. Sometimes, weights shall be assigned to choose between these criteria by which the degree of packet importance is calculated. This degree helps in mapping the packets to particular priority level and thereafter the priority assignment scheme shall take over. If priority assignment is complete without any partiality, resource sharing, the next phase of service differentiation will be taken care of by the underlying MAC layer based on the priority level, which has already indirectly encompassed the importance of packet data BIB009 .