Sensing is a technique used to gather information about a physical object or process, including the occurrence of events (i.e., changes in state such as a drop in temperature or pressure). An object performing such a sensing task is called a sensor. For example, the human body is equipped with sensors that are able to capture optical information from the environment (eyes), acoustic information such as sounds (ears), and smells (nose). These are examples of remote sensors, that is, they do not need to touch the monitored object to gather information.
The application layer contains a variety of application layer protocols to generate various sensor network applications. This layer performs various sensor network applications, such as:
1. Query dissemination.
2. node localization
3. time synchronization, and
4. network security.
Transport Layer
The transport layer is responsible for reliable data delivery required by the application layer between sensor nodes and the sink(s). Due to the energy, computation, and storage constraints of sensor nodes, traditional transport protocols cannot be applied directly to sensor networks without modification.
For example, the conventional end - to - end retransmission - based error control and the window – based congestion control mechanisms used in the transport control protocol (TCP) cannot be used for sensor networks directly because they are not efficient in resource utilization.
In addition, data delivery in sensor networks primarily occurs in two directions:
Network Layer
The network layer is responsible for routing the data sensed by source sensor nodes to the data sink(s).
In general, a source node can transmit the sensed data to the sink either directly via single - hop long – distance wireless communication or via multi-hop short - distance wireless communication.
In this case, to send the sensed data to the sink, a source node must employ a routing protocol to select an energy - efficient multihop path from the node itself to the sink.
Q/ Are the traditional routing protocols work with WSN?
1. Traditional wireless networks protocols are not suitable for sensor networks because they do not consider energy efficiency as the primary concern.
2. Also, data from the sensing region toward the sink exhibit a unique many - to - one traffic pattern in sensor networks. Thus, The combination of multihop (i.e., hop - by - hop) and many - to – one communications results in a significant increase in transit traffic intensity and thus packet congestion, collision, loss, delay, and energy consumption as data move closer toward the sink.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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