A Bandwidth Conserving Approach to Multiple Access Satellite Communication for Mobile Terminals
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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The problem of efficiently packing many mobile user signals into the available UHF uplink bandwidth of an advanced communications satellite is considered. The basic approach is FDMA with QPSK modulated data streams individually modified by spectral shaping using data windows. From extensive computer simulations it is concluded that with relatively little degradation 20 unsynchronized 16 kbps satellite users can be packed into a 500 kHz uplink bandwidth that is shared with terrestrial LOS allocations. Alternatively, 7 unsynchronized 2400 bps users can occupy a 25 kHz bandwidth. Signal strengths may vary by as much as 10 to 15 dB at the satellite without the need for transmitter power control.
- Radio Communications