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Published byLesley Singleton Modified over 9 years ago
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Wireless Multiple Access Multiple Simultaneous Connections By Dr. Larry Hash
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Multiplexing Multiple information streams combined FDM Separate frequency for each user For example - cable TV TDM Separate time slot for each user For example – T1 Synchronization is controlled at a single point for both downlink and uplink
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Multiple Access Similar to Multiplexing except Each uplink transmission comes from an independent transmitter Uplink synchronization control is distributed Types FDMA – Frequency Division Multiple Access For Example - Analog cell phones TDMA – Time Division Multiple Access For Example – GSM cell phones CDMA – Code Division Multiple Access For Example – 3 rd Generation cell phones
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FDMA Separate frequency for each user Uplink transmitter controls Frequency agile Frequency control Bit sync
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TDMA Separate time slot for each user Uplink transmitter controls Time slot timing Propagation time compensation Bit sync
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CDMA Separate code for each user Uplink transmitter controls Power control Bit sync
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Duplexing The reverse channel Mobile to Base FDD – Frequency Division Duplexing Reverse channel is assigned a separate frequency Separation from forward channel TDD – Time Division Duplexing Reverse channel is assigned a separate time slot CDD – Code Division Duplexing Reverse channel is assigned a separate code
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