1 Chapter 5 The Medium Access Sublayer

2 Chapter 5 The Medium Access Layer 5.1 The Channel Allocation problem - Static and dynamic channel allocation in LANs & MANs 5.2 Multiple Access Protocols - ALOHA, CSMA, CSMA/CD, Collision-free protocols, Limited- contention protocols, Wireless LAN protocols 5.3 Ethernet - Cabling, MAC sublayer protocol, Backoff algorithm, Performance, Gigabit Ethernet, Logical Link Control 5.4 Wireless LANs protocol stack, physical layer, MAC sublayer protocol, frame structure

3 5.5 Broadband Wireless - Comparison of with , protocol stack, frame structure 5.6 Bluetooth - Bluetooth architecture, Application, Protocol stack, Frame structure 5.7 Data Link Layer Switching - Bridges from 802.x to 802.y, Local internetworking, Spanning tree bridges, Remote bridges

4 5.1 The Channel Allocation problem Static channel Allocation in LANs and WANs Frequency Division Multiplexing (FDM)

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Dynamic Channel Allocation in LANs and WANs Assumptions 1.Station Model. The model consists of N independent stations, each generates the frame with probability in an interval. Once a frame is generated, the station is blocked. 2.Single Channel Assumption. A single channel is available for all communication. 3.Collision Assumption. If two frames are transmitted simultaneously, they are destroyed and must be retransmitted again later. There are no other errors.

8 4a. Continuous Time. Frame transmission can begin at any instant. 4b. Slotted Time. Time is divided into slots. Frame transmission always begin at the start of a slot. 5a. Carrier Sense. Stations can tell if the channel is in use before trying to use it. 5b. No Carrier Sense. Stations cannot sense the channel before trying to use it.

9 5.2 Multiple Access Protocols ALOHA 5-1.

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Carrier Sense Multiple Access Protocols

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