Ch4_Multiaccess_Communication-2008-5-rev

Ch4_Multiaccess_Communication-2008-5-rev - is ion...

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Multiaccess Communication Sunghyun Choi Adopted from Prof. Saewoong Bahk’s material
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Multiacess Reservations Reservation via mini-slot of duration v, then transmit data of average duration 1 via assigned data slots Max. throughput (in data packets/time unit) S r = 1/e for slotted Aloha, 0.478 for splitting, 1 for TDM 1 for reservation w/o data 1 / 1 for reservation w/ data cf. CSMA/CD 1 (1/ 1) r r S v S v S = + = + -
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Satellite Reservation Systems One way propagation delay of 260msec( ) Reservation use TDM, no limit on packet and frame sizes No reservation collision needed Single user reservation system (m=1) where the fixed reservation interval of A. β A N E R E W E i i i 2 ] [ ] [ ] [ + + = μ λ - + + - = 1 2 2 ) 1 ( 2 ˆ 2 A A X W
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Problem : the round-trip delay of 2 has been neglected. To be stable good)
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Unformatted text preview: is ion approximat the 1, (as 1 < System with separate frequency band for reservations (m=8) Fixed frame size 2 mv = : waiting time for the reservation slot : transmission time for the reservation packet 2 : waiting time for the reservation ACK : packet transmission time where X is the packet transmission time using the full bandwidth Utilization From the M/G/1 analysis ( ) 2 2 m 2 -1 X -= 1 2 X 2(1 ) W =- Perfect scheduling at the expense of the delay for making reservations 2 2 2 ( ) (1 ) 2(1 )(1 ) 2(1 ) 1 X X -=- ----) 1 )( 1 ( 2 2 3 2 ---+ + = X m W...
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This note was uploaded on 06/16/2008 for the course COMPUTER S 853 taught by Professor Choi during the Spring '08 term at Seoul National.

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Ch4_Multiaccess_Communication-2008-5-rev - is ion...

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