Impact of N-Policy on Quality of Service for Energy Efficient Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have attracted attention from both academia and industry since the late 90\u27s. Recent advancements in the technology of microelectromechanical systems (MEMS), the fields of digital electronics, and in wireless communication have resulted in the reductions of both the size and cost of sensor nodes. Even so, there are still some constraints on the performance of WSNs. The two most important constraints are the limited power supply in the sensor nodes and the difficulty in recharging or replacing their batteries. Therefore, reducing the energy consumption of Pensor nodes and optimizing the lifetime of WSNs are crucial. Wireless sensor networks have explored many new protocols, various approaches have been taken to design energy-efficient wireless sensor networks (EEWSNs). In this work, we conducted research on a packet queueing management model that offers different quality of services for packets coming from different sources. This model also incorporate N-policy to minimize excessive switching of transmission radio to conserve battery energy. In our daily life, we often experience waiting in a queue to receive some kind of service. Some customers do not join the queue at the end like other normal customers, and try to cut in the queue hoping to have a shorter waiting time and a higher level of satisfaction. This behavior is called customer interjection. First-come- first-served (FCFS) service discipline is usually assumed in public places like restaurants, banks, airports, and supermarkets. However, customer interjections can still be seen in these places. These interjections can affect the waiting time of other customers in queue. Such interjections may reduce the waiting time of interjecting customers, but increase the waiting time and of others. To control a queueing system, implementing a priority mechanism is a sensible approach. For example, at the airport, customers are categorized in to VIP and general customers. VIP customer has shorter lines and tailored services where as general customer usually stand in line longer and process takes longer to finish too. Priority queue management becomes more important in telecommunication systems also in computer systems (e.g. operating systems) they have been exploited for a long time. Priority queueing control is also used in other production practices. In this research we proposed a queue management model that has a priority queue and a normal queue at the same time. Our proposed model will service priority packets first then turn around to process normal packet until both queues are empty then turn off the radio. This seemingly simple design yields a complex set of balance equations. After solving all the equations with the help of probability generating functions we got the expected queue length for two queues

Modelling QoS for wireless sensor networks

A wireless sensor network (WSN) is a wireless network composed of spatially distributed and tiny autonomous nodes — smart dust sensors, motes —, which cooperatively monitor physical or environmental conditions. Nowadays these kinds of networks support a wide range of applications, such as target tracking, security, environmental control, habitat monitoring, source detection, source localization, vehicular and traffic monitoring, health monitoring, building and industrial monitoring, etc. Generally, these applications have strong and strict requirements for end-to-end delaying and loosing during data transmissions. In this paper, we propose a realistic scenario for application of the WSN field in order to illustrate selection of an appropriate approach for guaranteeing performance in a WSN-deployed application. The methodology we have used includes four major phases: 1) Requirements analysis of the application scenario; 2) QoS modeling in different layers of the communications protocol stack and selection of more suitable QoS protocols and mechanisms; 3) Definition of a simulation model based on an application scenario, to which we applied the protocols and mechanisms selected in the phase 2; and 4) Validation of decisions by means of simulation and analysis of results. This work has been partially financed by the “Universidad Politécnica de Madrid” and the “ Comunidad de Madrid” in the framework of the project CRISAL - M0700204174

Modelling QoS for Wireless Sensor Networks

Abstract: A wireless sensor network (WSN) is a wireless network composed of spatially distributed and tiny autonomous nodes -smart dust sensors, motes -, which cooperatively monitor physical or environmental conditions. Nowadays these kinds of networks support a wide range of applications, such as target tracking, security, environmental control, habitat monitoring, source detection, source localization, vehicular and traffic monitoring, health monitoring, building and industrial monitoring, etc. Generally, these applications have strong and strict requirements for end-to-end delaying and loosing during data transmissions. In this paper, we propose a realistic scenario for application of the WSN field in order to illustrate selection of an appropriate approach for guaranteeing performance in a WSN-deployed application. The methodology we have used includes four major phases: 1) Requirements analysis of the application scenario; 2) QoS modeling in different layers of the communications protocol stack and selection of more suitable QoS protocols and mechanisms; 3) Definition of a simulation model based on an application scenario, to which we applied the protocols and mechanisms selected in the phase 2; and 4) Validation of decisions by means of simulation and analysis of results. This work has been partially financed by the "Universidad Politécnica de Madrid" and the "Comunidad de Madrid" in the framework of the project CRISAL -M0700204174