DCNUNIT - III

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ALOHA, IEEE Project 802, Wired Lans - Ethernet Evolution, Standard Ethernet, Fast Ethernet (100 Mbps), Gigabit Ethernet,  Wireless Lans, IEEE 802.11 - Wifi, Bluetooth(IEEE 802.15),  Wimax (IEEE 802.16)

Unit 3 Notes for above topics - Download

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CSMA/CA

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Carrier Sense Multiple Access with Collision Avoidance Carrier sense multiple access with collision avoidance (CSMA/CA) was invented for wireless networks. Collisions are avoided through the use of CSMA/CA’s three strategies: the interframe space, the contention window, and acknowledgments, Interframe Space (IFS)   First, collisions are avoided by deferring transmission even if the channel is found idle. When an idle channel is found, the station does not send immediately. It waits for a period of time called the interframe space or IFS. Even though the channel may appear idle when it is sensed, a distant station may have already started transmitting. The distant station’s signal has not yet reached this station. The IFS time allows the front of the transmitted signal by the distant station to reach this station. After waiting an IFS time, if the channel is still idle, the station can send, but it still needs to wait a time equal to the contention window. The IFS vari...
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