第三章 无线传感器网络通信.pdfVIP

第第33章章 无线传感器网络通信无线传感器网络通信 1 3.1无线传感器网络协议结构 3.1.1传统网络协议OSI参考模型 开放式系统互联网络参考模型开放式系统互联网络参考模型(OSI)( OSI )共有共有77个层次个层次 ，如图如图33-11所示所示。从底从底 向上依次是物理层、数据链路层、网络层、传输层、会话层、表示层和应 用层。除物理层和应用层外，其余每层都和相邻上下两层进行通信。 2 The Levels of Abstraction  Multiple levels of communication abstractions have been defined by standardization bodies  Each level is enforced by a corresponding protocol  Each level uses the abstract services of the level belowbelow  Abstraction achieves separation of concerns  AA protocolprotocol neednneedn’tt knowknow howhow thethe lowerlower-levellevel abstractionsabstractions are implemented and what the higher level abstractions are. Layered Network Architecture  In a Layered Network Architecture, the services are groupedgrouped inin aa hierarchyhierarchy ofof layerslayers.  A protocol of layer N uses only services of layer N-1.  AA protocolprotocol ofof layerlayer NN providesprovides servicesservices onlyonly toto layerlayer N+1N+1.. notnot layeredlayered layeredlayered A B A B layer 3 C C layer 2 EE DD EE DD layer 1 Service Primitives  Assume that some protocol implements service “X” X . N+1N+1 LayerLayer ProtocolProtocol N+1 Layer N+1 Layer Entity Entity X. Request X. Confirm X. Indication X. Response N Layer N Layer Entiity