Communication has become inevitably part of our day to day activities, in academic, business, banking, and other sectors. It has therefore become so important to implement good and efficient communication system. A reference point according to this research is the wireless sensor networking (WSN) system, and most important thing in communication is to be free from interference, attenuation, crosstalk, and fading. Any of these factors is a serious problem in communication system. To solve these problems, mobile and fixed nodes networks were considered for efficient operation of WSN when ZigBee technology was employed and designed using the OPNET when certain network parameters: Throughput (bits/s), load (bits/s), and end-to end delay (second) parameters from fixed and mobile networks were compared and considered for smooth operation of WSN that is free from interference, attenuation, crosstalk and fading. The network investigation and performance analysis of fixed and mobile networks were based on tree, star and mesh topologies between the two systems. After considering all the parameters for various analyses, the fixed network was considered the most suitable over the mobile network for WSN.

Designing wireless sensor networks should meet appropriate parameters such as quality of service (QoS) defined by different users. The variable physical conditions of the environment, processing and transmission power limitations and limited communication capabilities are the most important obstacles that influence QoS parameters such as throughput, delay, reliability and network lifetime. The most important problems that directly have destructive effects on these parameters are hidden and exposed node problems. These problems extremely decrease throughput and increase delay and power consumption in the network. This paper proposes a new and efficient method to decrease the mentioned problems that relies on clustering, grouping and subgrouping strategy. Then different transmission powers are allocated to different nodes depending on their hierarchy level to communicate in their active time slots to decrease power consumption. This mechanism has been simulated by OPNET on IEEE802.15.4/Zigbee.

Advances in low-power electronics design and wireless communication have enabled the development of low cost, low power micro-sensor nodes. These sensor nodes are capable of sensing, processing and forwarding which have many applications such as underwater networks. In underwater wireless sensor networks (UWSNs) applications, sensors which are placed in underwater environments and predicted enable applications in oceanographic data collection, mine reconnaissance, pollution, assisted navigation, distributed tactical surveillance, and ocean sampling. Each sensor uses acoustic signals as its physical medium for communications. This study focuses on a priority-based routing protocol in underwater wireless sensor networks. This routing method tries to improve the QOS requirements with considering high and low priority traffic classes. Through simulation study using the OPNET simulator, we proved that proposed algorithm achieves high performance as compared to GEDAR, in terms of packet loss, end to end delay of data transmission and energy consumption.