Wireless Multiple Access Multiple Simultaneous Connections By Dr. Larry Hash

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

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

FDMA Separate frequency for each user Uplink transmitter controls Frequency agile Frequency control Bit sync

TDMA Separate time slot for each user Uplink transmitter controls Time slot timing Propagation time compensation Bit sync

CDMA Separate code for each user Uplink transmitter controls Power control Bit sync

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