Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the nodes. <s> BIB001 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated. <s> BIB002 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The IETF is currently working on service differentiation in the Internet. However, in wireless environments where bandwidth is scarce and channel conditions are variable, IP differentiated services are sub-optimal without lower layers' support. We present three service differentiation schemes for IEEE 802.11. The first one is based on scaling the contention window according to the priority of each flow or user. The second one assigns different inter-frame spacings to different users. Finally, the last one uses different maximum frame lengths for different users. We simulate and analyze the performance of each scheme with TCP and UDP flows. <s> BIB003 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Large-scale wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from traditional networked systems. This paper presents RAP, a new real-time communication architecture for large-scale sensor networks. RAP provides convenient, high-level query and event services for distributed micro-sensing applications. Novel location-addressed communication models are supported by a scalable and light-weight network stack. We present and evaluate a new packet scheduling policy called velocity monotonic scheduling that inherently accounts for both time and distance constraints. We show that this policy is particularly suitable for communication scheduling in sensor networks in which a large number of wireless devices are seamlessly integrated into a physical space to perform real-time monitoring and control. Detailed simulations of representative sensor network environments demonstrate that RAP significantly reduces the end-to-end deadline miss ratio in the sensor network. <s> BIB004 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> A quality-of-service (QoS) routing protocol is developed for mobile ad hoc networks. It can establish QoS routes with reserved bandwidth on a per flow basis in a network employing TDMA. An efficient algorithm for calculating the end-to-end bandwidth on a path is developed and used together with the route discovery mechanism of AODV to setup QoS routes. In our simulations the QoS routing protocol produces higher throughput and lower delay than its best-effort counterpart. <s> BIB005 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Advances in microsensor and radio technology enable small but smart sensors to be deployed for a wide range of environmental monitoring applications. The low-per node cost allows these wireless networks of sensors and actuators to be densely distributed. The nodes in these dense networks coordinate to perform the distributed sensing and actuation tasks. Moreover, as described in this paper, the nodes can also coordinate to exploit the redundancy provided by high density so as to extend overall system lifetime. The large number of nodes deployed in this systems preclude manual configuration, and the environmental dynamics precludes design-time preconfiguration. Therefore, nodes have to self-configure to establish a topology that provides communication under stringent energy constraints. ASCENT builds on the notion that, as density increases, only a subset of the nodes is necessary to establish a routing forwarding backbone. In ASCENT, each node assesses its connectivity and adapts its participation in the multihop network topology based on the measured operating region. This paper motivates and describes the ASCENT algorithm and presents analysis, simulation, and experimental measurements. We show that the system achieves linear increase in energy savings as a function of the density and the convergence time required in case of node failures while still providing adequate connectivity. <s> BIB006 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> In this paper, we present a real-time communication protocol for sensor networks, called SPEED. The protocol provides three types of real-time communication services, namely, real-time unicast, real-time area-multicast and real-time area-anycast. SPEED is specifically tailored to be a stateless, localized algorithm with minimal control overhead End-to-end soft real-time communication is achieved by maintaining a desired delivery speed across the sensor network through a novel combination of feedback control and non-deterministic geographic forwarding. SPEED is a highly efficient and scalable protocol for sensor networks where the resources of each node are scarce. Theoretical analysis, simulation experiments and a real implementation on Berkeley motes are provided to validate our claims. <s> BIB007 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The delivery of quality video service often requires high bandwidth with low delay or cost in network transmission. Current routing protocols such as those used in the Internet are mainly based on the single-path approach (e.g., the shortest-path routing). This approach cannot meet the end-to-end bandwidth requirement when the video is streamed over bandwidth-limited networks. In order to overcome this limitation, we propose multipath routing, where the video takes multiple paths to reach its destination(s), thereby increasing the aggregate throughput. We consider both unicast (point-to-point) and multicast scenarios. For unicast, we present an efficient multipath heuristic (of complexity O(|V|/sup 3/)), which achieves high bandwidth with low delay. Given a set of path lengths, we then present and prove a simple data scheduling algorithm as implemented at the server, which achieves the theoretical minimum end-to-end delay. For a network with unit-capacity links, the algorithm, when combined with disjoint-path routing, offers an exact and efficient solution to meet a bandwidth requirement with minimum delay. For multicast, we study the construction of multiple trees for layered video to satisfy the user bandwidth requirements. We propose two efficient heuristics on how such trees can be constructed so as to minimize the cost of their aggregation subject to a delay constraint. <s> BIB008 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> This paper presents an end-to-end reservation protocol for quality-of-service (QoS) support in the medium access control layer of wireless multihop mesh networks. It reserves periodically repeating time slots for QoS-demanding applications, while retaining the distributed coordination function (DCF) for best effort applications. The key features of the new protocol, called "distributed end-to-end allocation of time slots for real-time traffic (DARE), are distributed setup, interference protection, and scheduling of real-time data packets, as well as the repair of broken reservations and the release of unused reservations. A simulation-based performance study compares the delay and throughput of DARE with those of DCF and the priority-based enhanced distributed channel access (EDCA) used in IEEE 802.11e. In contrast to DCF and EDCA, DARE has a low, nonvarying delay and a constant throughput for each reserved flow <s> BIB009 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet's impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio--PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel). <s> BIB010 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Owing to the growing demand for low-cost 'networkable' sensors in conjunction with recent developments of micro-electro mechanical system (MEMS) and radio frequency (RF) technology, new sensors come with advanced functionalities for processing and communication. Since these nodes are normally very small and powered with irreplaceable batteries, efficient use of energy is paramount and one of the most challenging tasks in designing wireless sensor networks (WSN). A new energy-aware WSN routing protocol, reliable and energy efficient protocol (REEP), which is proposed, makes sensor nodes establish more reliable and energy-efficient paths for data transmission. The performance of REEP has been evaluated under different scenarios, and has been found to be superior to the popular data-centric routing protocol, directed-diffusion (DD) (discussed by Intanagonwiwat et al. in 'Directed diffusion for wireless sensor networking' IEEE/ACM Trans. Netw., 2003, 11(1), pp. 2-16), used as the benchmark. <s> BIB011 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The appearance of wireless multimedia sensor networks (WMSNs) requires a new generation transmission paradigm towards intelligent and ubiquitous communication. Video sensors are used in WMSNs to enhance the capability for event description. Multiple routing paths are often used for transmitting video streams. However, not every path found by multi-path routing algorithm is suitable for transmitting video, because a long routing path with a long end-to-end transmission delay may not satisfy the time constraint of the video. Furthermore, each video stream includes two kinds of information: image and audio streams. In different applications, image and audio streams play different roles, and the importance levels are different. Higher priority should be given to the more important stream (either the image stream or the audio stream) to guarantee the using of limited bandwidth and energy in WMSNs. In this paper, we propose a context-aware cross-layer optimized Multi-Path Multi-Priority (MPMP) transmission scheme, in which a Two-Phase geographic Greedy Forwarding (TPGF) multi-path routing protocol is used in network layer to explore the maximum number of node-disjoint routing paths, and a Context-Aware Multi-path Selection algorithm (CAMS) is used in transport layer to choose the maximum number of paths from all found node-disjoint routing paths for maximizing the gathering of the most valuable information to the base station. Simulation results show that the MPMP scheme can effectively maximize the gathering of the most valuable information and guarantee the end-to-end transmission delay. <s> BIB012 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The power awareness issue is the primary concern within the domain of Wireless Sensor Networks (WSNs). Most power dissipation ocurrs during communication, thus routing protocols in WSNs mainly aim at power conservation. Moreover, a routing protocol should be scalable, so that its effectiveness does not degrade as the network size increases. In response to these issues, this work describes the development of an efficient routing protocol, named SHPER (Scaling Hierarchical Power Efficient Routing). <s> BIB013 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> In this paper, we propose an efficient Two-Phase geographic Greedy Forwarding (TPGF) routing algorithm for WMSNs. TPGF takes into account both the requirements of real time multimedia transmission and the realistic characteristics of WMSNs. It finds one shortest (near-shortest) path per execution and can be executed repeatedly to find more on-demand shortest (near-shortest) node-disjoint routing paths. TPGF supports three features: (1) hole-bypassing, (2) the shortest path transmission, and (3) multipath transmission, at the same time. TPGF is a pure geographic greedy forwarding routing algorithm, which does not include the face routing, e.g., right/left hand rules, and does not use planarization algorithms, e.g., GG or RNG. This point allows more links to be available for TPGF to explore more routing paths, and enables TPGF to be different from many existing geographic routing algorithms. Both theoretical analysis and simulation comparison in this paper indicate that TPGF is highly suitable for multimedia transmission in WMSNs. <s> BIB014 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> This paper focuses on studying the performance of TPGF geographic routing algorithm with multi routing metric called McTPGF in random duty-cycled wireless multimedia sensor networks (WMSNs). The multi-metric contains the geographic distance and the time, which is called sleeping-delay in this paper, the forwarding node waits to forward packet to the neighbor node after it wakes up. We recognize the fact that in random duty-cycled WMSNs, geographic routing should not only consider the geographic distance of the neighbor node but also the sleeping-delay of the node at that moment. The significant difference between our work and the TPGF is that our work pays more attentions to the demand of finding a single routing path with low sleeping-delay at a certain time using TPGF while the traditional TPGF algorithm focuses on finding all node-disjoint paths in the given network topology. Simulations are conducted to evaluate that the McTPGF reduces the end-to-end delay with the cost of adding few hop counts compared with the traditional TPGF algorithm in random duty-cycled WMSNs. <s> BIB015 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless multimedia sensor networks (WMSN) emerges as an important category of Wireless Sensor Networks, which retrieves real-time information such as video and audio streams, still images etc. One of the prominent characteristics of WMSN is severe bandwidth limitation which has great impact on design of routing algorithm. In traditional routing protocols, path(s) are selected aiming at providing optimal transmission performance for the current flow while little attention is paid to bandwidth efficiency. This greedy strategy results in the existence of large amounts of bandwidth fragments which can’t be fully used so that the networks capability to carry real-time flows is degraded. In this paper, bandwidth efficient Collaborative Quality of service Routing (CQR) is proposed. The defining aspect of CQR is to collaboratively optimize the path selections of multiple flows over the networks. The CQR problem is formulized as linear programming. Resource allocation vector is constructed to decouple the inherently dependent path selections between different flows and sub-gradient based searching algorithm is proposed to get the optimal solution. Simulation results show that CQR achieves higher call admission rate for real-time flow comparing to existed algorithm, under heavy load CQR outperforms traditional algorithms about 40% in call admission rate and has similar transmission cost. <s> BIB016 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless multimedia sensor network (WMSN) takes more account of dealing with information-intensive data such as audio, image and video, it has much more wide foreground for application than traditional wireless sensor network. It has significance to research topology of WMSN aimed at some characteristic such as the larger media data capacity, limitation on computation, storage & energy and the requirements of transport quality. This paper introduces a novel clustered-control algorithm based on geographic locations, energy, priority of coverage, and multi-layers architecture. Detailed process is proposed including cluster heads’ election method and multimedia data transmission mechanism. The theoretical analysis and simulation experiments indicate that our improved algorithm can strengthen routing function, prolong the lifetime of network and reduce energy consumption. <s> BIB017 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The Wireless Multimedia Sensor Networks (WMSNs) consist of nodes that are capable of sensing, computing, communication, actuation, and power components. Some of the applications of the Wireless Sensor Multimedia Networks include habitat monitoring, target tracking, environmental monitoring, and traffic management systems, these applications require effective communication of event features in the form of multimedia such as audio, image, and video. Routing in Wireless Multimedia Sensor Network is an important issue since the WMSN nodes that sense the data need to be communicated to the base station, to take necessary decision. The key issues in the design of routing protocol in the WMSN are energy consideration, multimedia consistency, tight QoS expectations, and high bandwidth demands. Although many routing protocols have been proposed for the WMSNs, the design of a more efficient protocol in terms energy awareness and QoS still remain a challenge. This work involves the design of the routing protocol in wireless multimedia sensor networks which is power aware, reliable and has low latency in delivering the data from source node that is sensing the data to the destination node/sink node. The proposed new algorithm called MPDT: Multipath Data Transfer protocol provides simultaneous multiple paths for communication between any two nodes. This feature prolongs the lifetime of the network. Also from the data security point of view, MPDT is immune to some specific attacks. Simulation results show that the proposed protocol surpasses the conventional protocol in terms of energy consumption and network lifetime. <s> BIB018 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> In this paper, we are going to present a data dissemination protocol for wireless multimedia sensor networks (WMSN). The proposed protocol entitled as MLAF (Multimedia Location Aided Flooding) is used for packet dissemination in WMSN. MLAF considers network as a virtual grid. Depending on its geographical position, each node is placed in one of network cells. We prevent sending redundant packets, and as a result, network's consumed energy will be reduced. Proposed protocol considers priority for traffics. Depending on packet's priority, MLAF makes decision about its routing. Consumed energy and end to end delay are two main parameters in protocol design. The proposed protocol uses LAF as base. Different aspects of MLAF efficiency have been evaluated. Performed simulations show that MLAF has achieved all of its goals. <s> BIB019 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> In the design of routing protocol for Wireless Multimedia Sensor Networks(WMSNs),aiming at how to meet QoS transmission requirements as well as to improve the energy efficiency at the same time,an efficient routing protocol called Cluster-based Real-time Routing Protocol(CBRP) is proposed.CBRP can effectively integrate the geographic forwarding mechanism with uneven virtual grid-based clustering routing protocol and dynamically adjust the data packets transmission rate.Simulation results show that CBRP meets the requirement of QoS in real-time and reliability domains and can prolong the network life cycle. <s> BIB020 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Use of general and efficient routing protocols for wireless multimedia sensor networks (WMSN) is of crucial significance Similar to other traditional networks, in WMSN a noticeable proportion of energy is consumed due to communications. In addition to energy, depending on network's application, many other parameters are also considered. In this paper, a data centric routing protocol which considers end to end delay, reliability, energy consumption, lifetime and fairness have been taken into account. The Proposed protocol which is called MREEP (Multimedia Reliable Energy Efficient routing Protocol) provides sending traffics with different priorities and QoS requirements based on constraint based routing. We study the performance of MREEP using different scenarios. Simulation results show that MREEP has achieved its goals. <s> BIB021 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless Multimedia Sensor Network (WMSN), as a novel technology, has attracted more and more attention with its board applications nowadays. The paper discusses the major challenges in current WMSN and focusing on some protocols relatively better fitting in the requirement of WMSN. Then a novel routing protocol CBRP-L basing on Cluster-Based Real-time Routing Protocol (CBRP) is proposed in this paper, which cuts off the high delay connections and runs LEACH algorithm for these nodes to forming a new cluster. Theoretic analysis and simulations are provided to show that the proposed protocol can effectively solve the problem of congestion and energy consumption, caused by only one cluster head with too many neighbors. <s> BIB022 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless sensor networks can be used to deploy various applications to reflect the circumstance of environment. Video sensors used in wireless multimedia sensor networks (WMSNs) enhance such applications with multimedia data, but with specific characteristics requirement for the network. The aim of this work is to provide reliable data transport with multipath routing and load balancing congestion control mechanism in WMSN. In this paper, we proposed a Minimum Hop Disjoint Multipath routing algorithm with Time Slice load balancing congestion control scheme (MHDMwTS) to ensure reliability in WMSN. The simulation shows MHDMwTS is more reliable than basic routing schemes for transport multimedia data. <s> BIB023 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Wireless Sensor Networks (WSNs) have an ever increasing variety of multimedia based applications. In these types of applications, network nodes should ideally maximize QoS and minimize energy expenditures in video communication. This article presents PEMuR, a novel dual scheme for efficient video communication, which aims at both energy saving and high QoS attainment. To achieve its objectives, PEMuR proposes the combined use of an energy aware hierarchical routing protocol with an intelligent video packet scheduling algorithm. The adopted routing protocol enables the selection of the most energy efficient routing paths, manages the network load according to the energy residues of the nodes and prevents useless data transmissions through the proposed use of an energy threshold. In this way, an outstanding level of energy efficiency is achieved. Additionally, the proposed packet scheduling algorithm enables the reduction of the video transmission rate with the minimum possible increase of distortion. In order to do so, it makes use of an analytical distortion prediction model that can accurately predict the resulted video distortion due to any error pattern. Thus, the algorithm may cope with limited available channel bandwidth by selectively dropping less significant packets prior to their transmission. Simulation results demonstrate the effectiveness of the proposed scheme. <s> BIB024 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The field of wireless multimedia sensor networks (WMSN) is attracting more and more research community as an interdisciplinary field of interest. This type of network is low-cost, multifunctional due to advances in micro-electromechanical systems, and the proliferation and progression of wireless communications. However transmit multimedia information captured must satisfy the criteria of QoS , which increases energy consumption, fact that should be taken into consideration in the design of any routing protocols for WMSNs. In this paper we present routing protocol which we call an Energy Aware TPGF (EA-TPGF), that improves the Two Phase geographical Greedy Forwarding (TPGF). The basic idea is to take into account the residual energy of the nodes in the identification of pathways. Simulations and statistics produced by the simulator NeTtopo showing a significant contribution with regard to the extension of the life of the network. <s> BIB025 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> Abstract Wireless Multimedia Sensor Networks (WMSN) have been drawing considerable attention and discussion in recent years due to its potential applications in various fields. For WMSN, how to increase the throughput in constrained environments has become the main challenge. Multipath routing is a promising solution because it can improve the channel utilization rate, reduce transmission delay and balance the transmission load. To pursue high efficiency for a multipath routing scheme, we need to take the characteristics of wireless environments and sensor networks into careful considerations. Based on such considerations, this paper introduces a Geographic Energy-Aware non-interfering Multipath (GEAM) routing scheme which divides the whole network topology into many districts and simultaneously forwards data through these districts without interfering with each other – to achieve interference-free transmissions. Our scheme will adjust the load of each district according to the energy status of their nodes; it does not establish fixed paths in advance and will hence maintain high performance even when the topology changes rapidly. We meanwhile employ a simple way to deal with the hole problem. Simulation results show that, when compared with related routing schemes, our GEAM can achieve higher performance at real-time transmission and meanwhile distribute transmission loads more evenly to most of the nodes in the network. <s> BIB026 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The wireless sensor networks applications are supposed to solve the conflict of energy efficient communication and should achieve the desired QoS like communication delay. To overcome this challenge, we propose Power Adaptive SPEED (PASPEED) routing protocol which is capable of achieving application specific delays at low energy cost and can dynamically adapt routing decisions. PASPEED is location aware, stateless, localized routing protocol with minimal control overhead. PASPEED supports three features: (1) adaptive power control to minimize energy consumption (2) providing end-to- end delay guarantee (3) hole bypassing. It meets soft real-time deadline by maintaining a desired delivery speed across the sensor network. It chooses the most energy efficient node from possible next hop nodes which can provide the required delivery speed. Simulation results shows that PASPEED achieves better deadline miss ratio and video quality as compared with other existing protocols. <s> BIB027 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Dual-Metric Link/Path Cost-Dependent Routing Protocols. <s> The increasing availability of low-cost hardware along with the rapid growth of wireless devices has enabled the development of Wireless Multimedia Sensor Networks (WMSNs). Multimedia content such as video and audio streaming is transmitted over a WMSN which can easily be deployed with low cost. However, enabling real-time data applications in those networks demands not only Quality of Service (QoS) awareness, but also efficient energy management. Sensor network devices have limited energy resources. The limited energy poses significant threats on the QoS of WMSNs. In this paper, to improve the efficiency of QoS-aware routing, we examine an angle-based QoS and energy-aware dynamic routing scheme designed for WMSNs. The proposed approach uses the inclination angle and the transmission distance between nodes to optimize the selection of the forwarding candidate set and extend network lifetime. Simulation results indicate that considerable lifetime values can be achieved. <s> BIB028
Many routing schemes formulate routing decision based on a combination of two routing metrics. Such schemes which determine link/path cost using proper blend of two metrics are categorized as dual-metric link/path cost-dependent routing schemes. Under this category, a comparative summary of routing schemes surveyed is shown in Table 2 . Sequential Assignment Routing (SAR) is a priority based, table-driven, multipath routing algorithm BIB001 . Multiple paths are generated from each node to the sink node. These multiple paths are generated by creating multiple trees, each rooted from a one-hop neighbor of the sink. The remaining energy and delay are QoS metrics considered during the branching of the trees. After branching, out of all of the paths found, the source will choose the final path. To route a packet in the network, weighted QoS metric is calculated as the product of additive QoS metrics (remaining energy and delay) and a weight coefficient associated with the priority level of that packet. According to simulations, SAR performance is better than that of the minimum metric algorithm. However, because this approach is table driven, it requires a great deal of memory and does not scale efficiently for large networks. Additionally, the priority of the packet remains the same during transit from source to destination. RAP is a real-time, priority-based communication architecture designed for large-scale networks, providing highlevel query and event services for distributed microsensing applications BIB004 . The network stack of sensors consists of Location Address Protocol (LAP) in the transport layer, Geographic Forwarding (GF) protocol in the routing layer, Velocity Monotonic Scheduling (VMS) layer, and prioritized MAC layer. The heart of this algorithm is VMS policy, which computes the deadline-aware and distance-aware priority for each packet. Furthermore, VMS is divided into two scheduling policies called static velocity monotonic and dynamic velocity monotonic. At the source, static velocity monotonic computes a fixed requested velocity for each packet. The dynamic velocity monotonic scheduling policy computes the velocity at each intermediate node after the arrival of each packet. Packets generated by multiple sources and competing for shared communication channels at intermediate nodes must be handled by enforcing packet prioritization at the MAC layer. This function is performed with the help of modification of the initial wait time after the channel becomes idle and the back-off window increase function BIB003 . Simulation results show RAP reduces the end-to-end deadline ratio substantially. In RAP, the number of hops metrics is not considered in the evaluation of the priority of a packet. In addition, it does not support multipath routing. SPEED provides a soft-real-time guarantee with desired delivery speed across a sensor network BIB007 . To maintain an end-to-end delay proportional to the distance between the source and the destination, it provides support for uniform delivery speed. SPEED supports three types of services, namely, real-time unicast, real-time area multicast, and realtime area anycast. It uses three types of beacons, namely, periodic beacon, delay-estimation beacon, and backpressure beacon. The last two are on-demand beacons. A backpressure beacon is used to reduce congestion in the network layer. SPEED uses Stateless Nondeterministic Geographic Forwarding (SNGF), which provides soft, real-time, endto-end delivery. Additionally, SNGF does load balancing over a larger area, which helps to reduce congestion. SNGF adapts the MAC layer to reduce congestion further. SPEED is scalable, but although some portion of a network might support more speed, it cannot be increased beyond the maximum end-to-end delivery speed. No priority is considered for packets, and it does not ensure reliabile delivery of the packets. In another work presented by Politis et al., multipath video transmission is optimized with the help of packet scheduling algorithms BIB010 . This work improves the power efficiency of the network and perceived video quality at the receiver. In this work, the LEACH BIB002 protocol is modified and explored to establish bandwidth-efficient multiple paths between all cluster heads. Multiple paths are selected between source and destination based on video stream transmission rate requirements BIB008 . Based on an inbuilt feature of the H.264/AVC encoder, the protocol uses a recursive distortion prediction model that considers isolated errors, burst errors, and lag errors along with other parameters. For packet scheduling, two algorithms are used, namely, baseline packet scheduling and power-aware packet scheduling. Both scheduling algorithms drop packets based on a distortion prediction model. Power-aware packet scheduling uses the energy efficiency of cluster heads and bandwidth limitations of the channel to decide whether the packet should be transmitted or dropped. The model presented in this work was tested against real measurements and found to be extremely competent for WMSNs, but the performance of this scheme is very complex for larger transmission windows. Another work derived from TPGF BIB014 is McTPGF, which finds a single routing path in random duty-cycled WMSNs BIB015 . In this case, the next forwarding node is decided based on the distance between the sink and the neighboring node as well as the sleeping delay of the neighbor. Sleeping delay is the delay required to wake the respective neighbor node from a dormant state. Additionally, the second phase of TPGF is completely removed; to avoid path circles, it binds node ID and packet ID before forwarding the packet. During routing, the node forwards the packet only to an unbounded neighbor. This work shows improved average end-to-end delay compared with TPGF. However, in the duty-cycled network, clock drift affects the accuracy of wake-up time for sensor nodes; thus, the duty-cycling concept is not suitable for critical real-time applications. MPMP is a context aware, multipriority-based, optimized multipath cross-layer transmission technique that guarantees end-to-end delay BIB012 . The maximum number of nodedisjoint paths is found in the network layer using TPGF BIB014 . Out of these paths, the maximum number of paths are selected by Context Aware Multipath Selection (CAMS) in the transport layer. Here, the video stream is split into an audio stream and an image stream. Context information, namely, noise and brightness level, is used to decide the importance levels of image and audio streams. Two types of priorities are used in the CAMS algorithm: contextaware multimedia content-based priority and end-to-end transmission delay-based priority. These priorities are used by the CAMS algorithm to find the maximum number of paths that satisfy the end-to-end delay for each stream. For multiple sources and a single destination, 1-hop neighboring nodes may be overloaded and congested. This scheme does not support congestion control. As mentioned earlier, TPGF selects the same path in a fixed topology. Nodes on the same path are depleted very quickly compared with other nodes, causing further holes and reducing the lifetime of the network. This problem is overcome in EA-TPGF by considering the residual energy of the node along with distance BIB025 . This extended work of TPGF improves the lifetime of the network, but it is not suitable for time-critical applications because of more number of hops and more delay. EA-TPGF does not support scalar and multimedia data at the same time. Collaborative Quality of Service Routing (CQR) is designed for real-time flows to achieve bandwidth-efficient collaborative QoS routing BIB016 . This technique boasts of good admission rate with low cost for traffic compared with traditional Greedy QoS Routing (GQR) techniques BIB005 BIB009 . Multiple flows are scheduled in parallel, considering bandwidth requirements and noninterference of the links. Additionally, a subgradient optimization-based search algorithm is used to obtain optimal results. This technique addresses bandwidth resource fragmentation, which is observed in GQR techniques. It achieves a hard real-time guarantee compared with GQR but takes more time to find the optimal solution. A scheme with the objective of designing a layer-based cluster control algorithm along with routing is presented by Haiping and Ruchuan BIB017 . Based on geographic location, every layer is divided into fan-shaped fields. Additionally, every cluster is separated into twelve virtual cells, each differing from the next by a 30 ∘ angle. The priority of coverage for any node is calculated based on the current position of that node and the center position of the virtual cell (distance). Additionally, the probability of sending a test packet is calculated based on the ratio of remaining energy to the priority of coverage. This probability is used to determine the selection of the cluster head. ASCENT BIB006 is used for multimedia data transmission and is enhanced further with the introduction of a detection channel and data transmission channel in the wake-up mechanism. Here, intermediate nodes are used for the backbone path in case of higher packet loss. This work shows a network lifetime improvement over the ASCENT and Geographical Adaptive Fidelity (GAF) protocols  . However, the results for other performance metrics as claimed in this paper are not presented by the authors. In addition, due to wake-up mechanism this protocol is limited to nonreal-time applications. The Multi-Path Data Transfer (MPDT) protocol supports simultaneous multipath data transfer between any two nodes BIB018 . Multiple paths are explored in the route setup phase, which is based on a threshold value of residual energy of a node and number of already established paths through that node. After multiple paths are explored, the data is split into parts ( paths) and encoded with the Reed-Solomon encoding technique at the source in the data transmission phase. This routing ensures distribution of work in a uniform manner among sensor nodes to boost network lifetime. However, multiple routing paths are not optimized, resulting in high end-to-end delay, which is not suitable for timecritical applications. Additionally, splitting data at the source on multiple paths causes extra overhead for data collection at the sink node. Based on REEP BIB011 , Multimedia Reliable Energy Efficient routing Protocol (MREEP) is a data-centric protocol designed for constraint-based routing for real-time and nonreal-time traffic flows BIB021 . It consists of four different phases, namely, data dissemination, event report, route establishment, and data forwarding phase. In the data dissemination phase, Multimedia Location Aided Flooding (MLAF) is used by the sink BIB019 . MLAF considers energy and end-toend delay as metric parameters to achieve reliability. MLAF defines four different priorities out of which two are used for directional forwarding, and the remaining two are used for delay-sensitive forwarding. During the route establishment phase for MREEP, two priority levels are considered, namely, high priority for real-time traffic and low priority for nonrealtime traffic. Routing tables for both real-time and nonrealtime traffic are created at each node at the end of this phase. Thus, routing tables store the highest priority record as the first record in the table. Next hop selection is based on the probability value of the record, which is the ratio of the length of the record path (distance) to the number of hops of the record. Compared with REEP, simulation results show that MREEP is more energy efficient, but because it uses MLAF, which is based on a grid arrangement, MREEP is restricted to a few applications. In addition, because of a table-driven approach it is not scalable. CBRP-L is a Cluster-Based Real-Time Protocol that combines two previous protocols, LEACH BIB002 and CBRP BIB020 , in its implementation BIB022 . In high node density areas, end-to-end delay is very high, which causes congestion. This algorithm focuses on detecting this congestion through affected links. Congested links with more than average delay will be disconnected by a node removing an entry from its table. Additionally, the LEACH algorithm is executed to elect a new cluster head to maintain the reliability of the entire network. CBRP-L shows better performance compared with its predecessor CBRP, but uneven virtual grid-based clustering and different cluster-head selection increase overhead, resulting in more complexity. MHDMwTS is a reliable Minimum Hop Disjoint Multipath routing algorithm With a Time-Slice load balancing congestion control scheme BIB023 . Three routing paths are formed based on minimum time delay and hop count from source to sink, namely, primary path, alternate path, and backup path. In normal operation, only the primary and alternate paths are used according to a time slice. The source will alternatively switch data on both of these paths per time slice. The time slice for the primary path is greater compared with the alternate path. Congestion is avoided by setting time slice appropriately at the major node. If the buffer space of the major node's queue reaches a threshold value, it sends a congestion notification message to the source node. In turn, the source stops transmitting data on this path by switching to another path. This algorithm works well at lower data rates, but at higher data rates performance drops significantly. Based on Scalable Hierarchical Power Efficient Routing (SHPER) BIB013 , PEMuR is a fusion of video packet scheduling with an energy-aware hierarchical routing protocol BIB024 . During the initialization phase, the base station forms cluster heads based on their residual energy. Cluster heads are divided into two types, namely, upper-level cluster heads and lower-level cluster heads. Lower-level cluster heads are away from the base station, and based on the routing index, they use upper-level cluster heads to communicate with the base station. The routing index is derived from residual energy and required energy to route a message between two chronological cluster heads. In the case of an event, the cluster head selects a node with the highest threshold residual energy to transmit multimedia data to itself. For packet-scheduling algorithm, it uses a distortion prediction model. According to this model, it drops packets when the transmission rate is greater than the available rate. PEMuR is a good choice for surveillance applications but causes extra overhead due to centralized cluster creation. Additionally, in case the transmission window is large, according to the distortion prediction model, the source requires more power and time to compare each packet with other packets. GEAM is a multipath routing scheme with interpath interference-free transmission BIB026 . Here, the entire topology is divided into various districts between source and sink; further districts are divided into three groups. During transmission, multipath interference is avoided by setting the distance between any two districts to more than two times the transmission radius. An intermediate node forwards a packet to the next node that belongs to the same district; likewise, it is forwarded toward the sink. During transmission, a packet is piggybacked with location and energy information of a node along with data. The sink sends this information to the source. Furthermore, the source adjusts the load in each district. When the source detects the presence of network holes, it changes the district boundary to accommodate the routing path. GEAM shows good performance for real-time traffic, but multipath noninterference criteria may incur a penalty of a greater hop count. The Power Adaptive SPEED (PASPEED) protocol is extended from SPEED BIB007 , which adapts the power control transmission to reduce energy consumption BIB027 . A forwarding node is selected that can satisfy the required delivery speed to guarantee end-to-end delay. A neighboring node that makes the most progress toward the sink is the next forwarding node. Progress is calculated based on the distance and the delay with respect to the neighboring node. Here, every node also determines the amount of transmission power required to send the packet to each neighbor. Based on this requirement, a node adapts transmission power out of eight different levels. This adaption of transmission power reduces energy consumption, resulting in an increase in network lifetime. Packet priorities are considered based on the type of frame (I-frame, P-frame, and B-frame). When congestion occurs, lower priority (importance) packets are dropped, improving the reliability of important packets, which results in better video quality. However, clock synchronization may cause a problem on the performance of the PASPEED. Angle-Based Dynamic Routing Scheme (ADRS) provides source location privacy against an adversary BIB028 . It guarantees transmission with average latency and improves the lifetime of the network. A set of forwarding neighboring nodes is selected based on the distance and inclination angle with respect to the sink node. Each time next forwarding node is selected randomly from the set. This random selection of node boosts the lifetime of the network. Latency constraint can be adjusted by controlling inclination angle and the distance between the current node and the neighboring node. Implicitly, it supports the hole-bypassing feature. ADRS lacks support for packet priority and has higher latency that is not suitable for real-time applications.