chức năng. Lớp liên kết dữ liệu có trách nhiệm để truyền, khung, và kiểm soát lỗi trong một liên kết cụ thể. Lớp mạng bao gồm các kết thúc cao hơn của bộ điều khiển liên kết, thiết lập và duy trì các liên kết nhiều, và hầu hết các chức năng quản lý Link (LM). | 148 ARCHITECTURE OF WIRELESS LANs Applications Application RFCOMM SDP Presentation L2 CAP Session HCI Transport LM Link controller Network Baseband Data link Radio Physical Bluetooth protocol stack OSI reference model Figure The Bluetooth protocol stack and OSI reference model. function. The data link layer is responsible for transmission framing and error control over a particular link. The network layer covers the higher end of the link controller setting up and maintaining multiple links and most of the Link Manager LM functions. The network layer is responsible for data transfer across the network independent of the media and specific topology of the network. The transport layer covers the high end of the LM and overlaps the Host Controller Interface HCI . The transport layer is responsible for reliability and multiplexing of data transfer across the network to the level provided by the application. The session layer covers Logical Link Control and Adaptation Protocol L2CAP and the lower end of RFCOMM SDP where RFCOMM is a protocol for RS-232 serial cable emulation and Service Discovery Protocol SDP is a Bluetooth protocol that allows a client to discover the devices offered by a server. The session layer provides the management and data flow control services. The presentation layer covers the main functions of RFCOMM SDP and provides a common representation for the application layer data by adding service structure to the units of data. The application layer is responsible for managing communications between host applications. A Bluetooth device is in one of the following states Standby state in which the device is inactive no data is being transferred and the radio is not switched on. In this state the device is unable to detect any access codes. Inquiry state when a device attempts to discover all the Bluetooth-enabled devices in its local area. Inquiry scan is used by devices to make themselves available to inquiring devices. Page state is entered by .
