Study the Effect of The Announcement Traffic Indication Messages Window ATIM Size on the Performance of the Ad-hoc Networks in Power Saving Mode PSM

The researches were interested in power saving in IEEE 802.11 standard in both of infrastructure networks and ad-hoc networks, where the power saving is one of the critical issues affecting wireless local area networks WLANs performance, especially ad-hoc networks, because each mobile device operates on the power of its limited battery. In ad-hoc networks which are called the independent basic service set IBSS  the power is saved by power saving mode PSM algorithm which depends on dividing the time into a number of  Beacon  intervals BIs, these intervals begin with a small period called announcement traffic indication messages window  ATIM period during which all the nodes are in the active mode. In this article, we study the effect of the announcement traffic indication messages window ATIM size on the performance of the  wireless networks in terms of power consumption and  throughput of the wireless network through several scenarios in the power saving mode PSM that differs in terms of the number of nodes used in the wireless network and the size of ATIM window. اهتم الباحثون بموضوع توفير الطاقة في معيار IEEE 802.11  في كل من الشبكات ذات البنية التحتيةInfrastructure  وشبكات Ad-hoc حيث يعد موضوع توفير الطاقة من القضايا الحرجة والمؤثرة على أداء الشبكات المحلية  اللاسلكية WLANs وخصوصا في شبكات Ad-hoc وذلك لأن كل جهاز جوال يعمل بالاعتماد على طاقة بطاريته المحدودة. يتم توفير الطاقة في شبكات Ad-hoc والتي تسمى مجموعة الخدمة الأساسية المستقلة IBSS باستخدام خوارزمية وضع توفير الطاقة PSM التي تعتمد على تقسيم الزمن إلى عدد من الفواصل الزمنية لإطار المرشد اللاسلكيBIs وتبدأ هذه الفواصل بفترة زمنية صغيرة للإعلان عن أطر التحكم تسمى بفترة نافذة رسائل إعلان إشارات المرور ATIM  تكون خلالها كافة العقد في وضع النشاط. تم في هذه المقالة دراسة تأثير اختلاف حجم نافذة ATIM على أداء الشبكة اللاسلكية من ناحية الطاقة المستهلكة ومردود الشبكة اللاسلكية وذلك من خلال عدة سيناريوهات في وضع توفير الطاقة PSM تختلف فيما بينها من ناحية عدد العقد المستخدمة في الشبكة اللاسلكية وحجم نافذة  ATIM

Energy efficiency in wireless networks

Energy is a critical resource in the design of wireless networks since wireless devices are usually powered by batteries. Battery capacity is finite and the progress of battery technology is very slow, with capacity expected to make little improvement in the near future. Under these conditions, many techniques for conserving power have been proposed to increase battery life. In this dissertation we consider two approaches to conserving the energy consumed by a wireless network interface. One technique is to use power saving mode, which allows a node to power off its wireless network interface (or enter a doze state) to reduce energy consumption. The other is to use a technique that suitably varies transmission power to reduce energy consumption. These two techniques are closely related to theMAC (Medium Access Control) layer. With respect to power saving mode, we study IEEE 802.11 PSM (Power Saving Mechanism) and propose a scheme that improves its energy efficiency. We also investigate the interaction between power saving mode and TCP (Transport Control Protocol). As a second approach to conserving energy, we investigate a simple power control protocol, called BASIC, which uses the maximum transmission power for RTS-CTS and the minimum necessary power for DATA-ACK. We identify the deficiency of BASIC, which increases collisions and degrades network throughput, and propose a power control protocol that addresses these problems and achieves energy savings. Since energy conservation is not an issue limited to one layer of the protocol stack, we study a cross layer design that combines power control at the MAC layer and power aware routing at the network layer. One poweraware routing metric is minimizing the aggregate transmission power on a path from source to destination. This metric has been used along with BASIC-like power control under the assumption that it can save energy, which we show to be false. Also, we show that the power aware routing metric leads to a lower throughput. We show that using the shortest number of hops in conjunction with BASIC-like power control conserves more energy than power aware routing with BASIC-like power control