132B_1_Sec03_MAC_090710A

132B_1_Sec03_MAC_090710A - Multiple Access Networking...

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Multiple Access Networking Professor Izhak Rubin rubin@ee.ucla.edu Electrical Engineering Department UCLA © 2010-2011 by Professor Izhak Rubin
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Prof. Izhak Rubin 2 Information Sources ± Analog; Digital ± Real-time ± Store and Forward 1 2 3 4 1 2 3 4 1 2 3 4 Real-Time Transmission of a Stream Time Frame=125 microsec Time Frame Time Frame ± Examples: ± Voice ± Video ± Imaging ± Facsimile ± Data
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Prof. Izhak Rubin 3 Multiplexing ± Definition : Sharing communication channel (service) resource among collocated stations (clients) ± Stations are said to be “collocated” when there is a low- delay low-cost mechanism for scheduling controlling and coordinating their use of the shared resource ± Note : Messages fed into the Mux reside in a common buffer facility; scheduler then orderspackets for transmission across channel using ‘designated slots.’ MUX DeMUX Communication Channel
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Prof. Izhak Rubin 4 Multiplexing Methods ± 1. Fixed Assigned: channel resource dedicated to a link flow ± Frequency Division Multiplexing (FDM) ± Time Division Multiplexing (TDM) ± Wavelength Division Multiplexing (WDM) ± 2. Demand Assigned: channel resource allocated on demand ± Asynchronous Time Division Multiplexing (ATDM) – Statistical Multiplexing
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Prof. Izhak Rubin 5 Time Division Multiplexing (TDM)-1 1 2 3 4 1 2 3 4 1 2 3 4 Time Frame Time Frame Time Frame Time t MUXed Comm Channel Rx Tx Station 3 Messages Received Across Channel Message Arrivals For Tx Queue Queue Tx in slot 3 of every frame MUX DeMUX Communication Channel Control process, or via net management, used to allocate a slot for transmissions from station-i to station-j. Assignment is fixed, or (slowly) programmable. Rx in specified slots
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Prof. Izhak Rubin 6 Time Division Multiplexing (TDM)-2 1 2 3 4 1 2 3 4 1 2 3 4 Time Frame Time Frame Time Frame Time t MUXed Comm Channel Rx Tx Station 3 Messages Received Across Channel Message Arrivals For Tx Queue Queue Head of the line packets are destined to stations 4,3,2 From slot 3 in each frame MUX DeMUX Communication Channel Control process, or via net management, used to allocate a slot for transmissions from station-i to station-j. Assignment is fixed, or (slowly) programmable.
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Prof. Izhak Rubin 7 Frequency Division Multiplexing (FDM) - 1 Frequency Band 2 Frequency Band 3 Frequency Band 4 Frequency Band 1 MUXed Comm Channel Frequency Rx Tx Station 2 Messages Received Across Channel Message Arrivals For Tx Queue Queue Received in specified Band MUX DeMUX Communication Channel Control process, or via net management, used to allocate band-k for transmissions from station-i to station-j. Assignment is fixed, or (slowly) programmable.
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Prof. Izhak Rubin 8 Frequency Division Multiplexing (FDM) - 2 Frequency Band 2 Frequency Band 3 Frequency Band 4 Frequency Band 1 MUXed Comm Channel Frequency Rx Tx Station 3 Messages Received Across Channel Message Arrivals For Tx Queue Queue Head of the line message is destined to
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132B_1_Sec03_MAC_090710A - Multiple Access Networking...

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