: A Wireless Sensor Network (WSN) is an effective sensing technology that is used to replicate the human capability of sensing, collecting, computing, processing and transmitting the data that is collected from a very large area. In recent past, sensor technology has shown tremendous development in the field of environment & health monitoring, military surveillance, vehicle tracking, and detection. The participating sensor nodes are prone to failure because of limited resources. The topology of the networks is highly dynamic in nature because of frequent failure of the sensor nodes. The Quality of Service support to highly dynamic networks is one of the challenging tasks. The dynamic nature, unpredictable topology, the demand of miniature size of the devices, tiny size of sensors and limited resources attract the researchers towards the designing of QoS aware protocols. This paper has discussed the architecture, applications, life cycle and types of WSN. Further, various QoS protocols, their limitations, and challenges have also been discussed. Further, this paper presents the most important open issues and challenges in providing QoSs provisioning to the WSN as QoS routing, energy consumption, bandwidth utilization, security, and mobility. This comprehensive review surely helps the researchers to find the new existing challenges and also help them to design new research problems for their future work.

The conventional routing protocols in mobile ad hoc network (MANET) using conventionally a common transmission power for both tranmsission and overheads to transfer the data packet from the source to the destination node have been revisted. Hence, an technique was developed to establish an algorithmAdaptive-Transmission-Power Ad Hoc OnDemand Distance Vector (ATP-ADOV) routing protocol -to control the transmission of power dynamically and overheads in MANET. The proposed ATP-ADOV reduced the energy consumption in the networks and improved the lifetime of the particiapting mobile nodes as well as that of the lifespan of the networks.

The necessary background as well as the details of simulation was presented to simulate and evaluate the performance of the ad hoc on-demand distance vector routing protocol in mobile ad hoc network with the help of the network simulator NS2 using the common transmission range to deliver the data packets at the destination node. The number of participating nodes played an important role to predict the conditions for the best performance of the protocol with respect to throughput, delay, packet delivery ratio, drop packets, consumed and residual energy of the network. Further, the efforts can be put to control the transmission range dynamically and overheads for reducing the energy consumption in the network and improving its lifetime of the nodes and the lifespan of the network.

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As all the participating mobile nodes are mobile in nature in MANET and due to frequent movement of the participating mobile nodes, it is very difficult to predict the topology of the networks at any time. Which leads to frequent route failures and route discovery mechanism are required to activate very frequently, it causes a loss of significant amount of energy to perform the various operations among the participating mobile nodes of the networks. As all the participating mobile nodes are rely on limited consumable power supply. Therefore, energy management is one of the challenging tasks in MANET.