Carrier Sensing Protocols
The Aloha schemes, described in the previous chapter, exhibited fairly poor performance which can be attributed to the “impolite” behavior of the users namely, whenever one has a packet to transmit he does so without consideration of others. It does not take much to realize that even little consideration can benefit all. Consider a behavior that we generically characterize as “listen before talk”, that is, every user before attempting any transmission listens whether somebody else is already using the channel. If this is the case the user will refrain from transmission to the benefit of all; his packet will clearly not be successful if transmitted and, further, disturbing another user will cause the currently transmitted packet to be retransmitted, possibly disturbing yet another packet.
KeywordsPropagation Delay Collision Detection Busy Period Successful Transmission Idle Period
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