A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Open Challenges. <s> The critical links whose failures significantly deteriorate the performance in a network must be protected not to fail or to be rapidly switched to their backup links. The number of these links should be small to restrict the investment cost of facilities and the operational cost for Internet service providers. Therefore, it is important to find the smallest number of links to be protected such that the diameter of the resulting graph by the failures of non-protected links is less than or equal to a given value. In this paper, we formulate this new link protection problem and prove that the problem is NP-hard. In addition, we propose a polynomial-time algorithm to solve the problem that the number of the simultaneous link failures is restricted to one. As about 70% of unintentional failures, excluding ones caused by maintenance, are single link failures, our algorithm for the restricted problem is not only theoretically important but also actually useful. <s> BIB001 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Open Challenges. <s> We provide a comparative analysis of various routing strategies that affect the end-to-end performance in wireless mesh networks. We first improve well-known link quality metrics and routing algorithms to enhance performance in wireless mesh environments. We then investigate the route optimality, i.e., whether the best end-to-end route with respect to a given link quality metric is established, and its impact on the network performance. Network topologies, number of concurrent flows, and interference types are varied in our evaluation and we find that a non-optimal route is often established because of the routing protocol's misbehavior, inaccurate link metric design, interflow interference, and their interplay. Through extensive simulation analysis, we present insights on how to design wireless link metrics and routing algorithms to enhance the network capacity and provide reliable connectivity. <s> BIB002 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Open Challenges. <s> This paper considers a network where nodes are connected randomly and can fail at random times. The critical- node test detects nodes, whose failures are malicious behavior, disconnects or significantly degrades the performance of the network. The critical node is an element, position or control entity whose disruption, is immediately degrades the ability of a force to command, control or effectively conducts combat operations. If a node is critical node, then more attention must be paid to it to avoid its failure or removal of a network. So how to confirm critical nodes in the ad hoc network is the premise to predict the network partition. A critical node is the most important node within the entity of a network. This paper suggests methods that find the critical nodes of a network based on residual battery power, reliability, bandwidth, availability and service traffic type. The metrics for evaluation has been considered as packet delivery ratio, end-to-end delay and throughput. Nodes in Mobile Ad hoc Networks (MANETs) are battery powered and hence have limited lifetime. Due to excessive utilization a node may die which can result in energy depletion problem and thereby affect overall network performance. Local rate of energy consumption based on application can be monitored. Thus early detection and avoidance of energy depletion problem is possible based on monitoring of power and remaining battery lifetime. As and when the rate of consumption based on the application returns to efficient levels, the mobile relay is released so that it can be made available for other critical nodes. This technique can be applied to any protocol used in MANETs such as DSDV, DSR, AODV, TORA etc. In this work, we focus on maximizing avoidance of network partition, rather than after the network partition, then taking some remedial measures. We describe the critical nodes compensation approach to increase the network connectivity and improve packet delivery rate. First, we detect the critical nodes which may lead to the network partitioning. Secondly, propose the compensation algorithm to avoid the network partitioning. This approach described in this paper is built around the notion of a critical node in an ad hoc network. Our definition of a critical node is a node, whose failure or malicious behavior disconnects or significantly degrades the performance of the network. Once identified, a critical node can be monitored in terms of resource. If a node is not considered critical, this metric can be used to decide if the application or the risk environment warrant the expenditure of the additional resources required to monitor, diagnose, and alert other nodes about the problem. Determining the global network topology in a MANET gives the time delays of the diagnostic packets and the mobility of the nodes makes this task futile, but determining an approximation of this topology or subset of this topology, within a certain time frame may be useful. An approximation of the network topology can still provide useful information about network the density, network mobility, critical paths, and critical nodes. Even with the uncertainty associated with correctly reconstructing the network topology for a given time period, this additional information can help to reduce the resources consumed to monitor all nodes in the absence of this information. <s> BIB003 </s> A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs <s> Open Challenges. <s> In order to gather information more efficiently in terms of energy consumption, wireless sensor networks (WSNs) are partitioned into clusters. In clustered WSNs, each sensor node sends its collected data to the head of the cluster that it belongs to. The cluster-heads are responsible for aggregating the collected data and forwarding it to the base station through other cluster-heads in the network. This leads to a situation known as the hot spots problem where cluster-heads that are closer to the base station tend to die earlier because of the heavy traffic they relay. In order to solve this problem, unequal clustering algorithms generate clusters of different sizes. In WSNs that are clustered with unequal clustering, the clusters close to the base station have smaller sizes than clusters far from the base station. In this paper, a fuzzy energy-aware unequal clustering algorithm (EAUCF), that addresses the hot spots problem, is introduced. EAUCF aims to decrease the intra-cluster work of the cluster-heads that are either close to the base station or have low remaining battery power. A fuzzy logic approach is adopted in order to handle uncertainties in cluster-head radius estimation. The proposed algorithm is compared with some popular clustering algorithms in the literature, namely Low Energy Adaptive Clustering Hierarchy, Cluster-Head Election Mechanism using Fuzzy Logic and Energy-Efficient Unequal Clustering. The experiment results show that EAUCF performs better than the other algorithms in terms of first node dies, half of the nodes alive and energy-efficiency metrics in all scenarios. Therefore, EAUCF is a stable and energy-efficient clustering algorithm to be utilized in any WSN application. <s> BIB004
The open challenges faced by MANETs according to Shivasankar et al. BIB003 are bandwidth constraints, location dependent contention, quick route reconfiguration, loop free routing, reliability based on signal strength, residual battery power, minimize power consumption per packet, availability, and residual capacity. To conserve battery energy of the nodes, there are various routing algorithms and schemes designed to select alternative routes. These algorithms and schemes are collectively known as "power-aware routing protocols. " To conserve energy, we would like to minimize the amount of energy consumed by all packets traversing from the source node to the destination node. Conserving energy neglects power consumption at individual nodes, which speeds up network partition by draining batteries of the critical nodes in the network one by one. The route between the partitions must go through one of these critical nodes. Therefore early identification and strengthening of critical node is a major issue to be tackled in a timely manner. As a solution, we adapt the idea of link protection for mobile ad hoc networks. Kim et al. BIB002 observe that unexpected protocol behavior and inaccurate design of link metric cause nonoptimal route construction based on which the end-to-end performance is degraded. Interference generated by background traffic or from other sources can disturb the optimal route construction, thus making the resultant performance even worse. Accordingly, there is a need to design robust protocol operation and accurate link quality metric which are able to be unaffected by interference, thus building the optimal route in a robust manner. The link protection approach BIB001 aims to find the smallest number of links to be protected such that the diameter of the resulting graph by the failures of nonprotected links is less than or equal to a given integer. This problem is important not only from a theoretical viewpoint, but also from a practical viewpoint, as ISPs can enhance the reliability of their networks by protecting the small number of the critical links whose failures significantly deteriorate the performance in a network. Alternatively, in a MANET the mobile nodes shall be clustered under various cluster heads. But this clustering should be performed considering the remaining battery power. However, due to heavy traffic, cluster heads close to base station may deplete their energy at a faster rate. This is popularly known as "hot spot" problem. Bagci and Yazici BIB004 propose a fuzzy energy-aware unequal clustering algorithm (EAUCF) that addresses the hot spots problem. EAUCF aims to decrease the intracluster work of the cluster heads that are either close to the base station or have low remaining battery power. A fuzzy logic approach is adopted in order to handle uncertainties in cluster-head radius estimation. A similar idea is yet to be applied in MANETs too to preserve nodes from becoming critical or to recover nodes that are in critical state.