dB =10log P1 P2

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! If busy ! The packet is backed off and the algorithm is repeated (for non-persistent) ! Station defers until channel idle and immediately transmits for 1-persistent ! The p-persistent, the station defers until the channel is idle then follows the channel idle procedure ! MAC layer adds inter frame spacing ! Packet unsuccessfully sent n times ! Next transmission attempt is delayed r times the base backoff ! Base backoff is usually twice the round trip propagation delay ! Uniformly distributed integer 0"r#2 k ! Where k=min(n,10), k is the minimum number of presently attempted transmissions 109 ! Collisions may still occur ! In that case, station aborts transmission ! Sends jamming signal of duration b ! Dimensionless, analogous to a ! Stations involved in collisions wait a random time prior to attempting re-transmission ! Ethernet uses truncated binary exponential backoff ! Transmission retries continue until success or 16 attempts are made ! Packet is then discarded 111 112 110
Reprinted with permission from Takagi and Kleinrock,17 © 1987, 115 IEEE! 113 114 ! Deterministic ! Signals are used to grant permission to transmit ! No collisions ! Control may be centralized or distributed ! Polling is a centralized method 116
Page 1 and 2: ! Results from the losses in the tr
Page 3 and 4: ! The end-to-end transfer of data f
Page 5 and 6: ! The major causes of bit errors ar
Page 7 and 8: ! Refers to the method used to dete
Page 9 and 10: ! Synchronous bit pipe ! Sending si
Page 11 and 12: ! DLL Protocols are sets of specifi
Page 13 and 14: ! When the receiver encounters a #
Page 15 and 16: ! Control frames are not control ch
Page 17 and 18: ! HDLC has three modes of data tran
Page 19 and 20: ! The P/F field is a single bit wit
Page 21 and 22: 81 82 83 ! Several protocols under
Page 23 and 24: ! A LAN is a community of users who
Page 25 and 26: ! Transmit and wait (2T prop ) for
Page 27: 105 107 ! Scaling to t p, At t=0,ch

dB =10log P1 P2

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