N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 9 - Wireless Systems and Technologies                                                                                   Slide 8 of 80                                                                                                    ________________

    Frequency Division Multiplexing Access (FDMA)

NIU - Network Interface Unit

                               Separate frequency allocations are used from each
                                                  customer site to the base station

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Frequency Division Multiplexing Access (FDMA) technique divides the available frequency spectrum into frequency band segments (channels). Each segment can support one user for the duration of a call.

For example: Advanced Mobile Phone Service (AMPS) - Analogue service

System bandwidth:    40 M Hz in 800 M Hz band (U.S.)

Uplinks:    20 M Hz  (825 - 845 M Hz)

Downlinks:    20 M Hz (870 - 890 M Hz)

Segments Per Links:  333 to 416

Segment bandwidth:  30 K Hz

A full duplex operation (one conversation) requires two segments.