M-link multiplexing and demodulation for the quadrature channel
Abstract
In QPSK signaling two independent data streams are transmitted over a single carrier channel by separately encoding each onto a quadrature component of the carrier. In this paper, the possibility of encoding M independent (nonsynchronized and unrelated in data rate) bit streams simultaneously over the same quadrature channel is investigated. The multiplexing can be viewed as the generation of a phase modulated carrier which can phase shift at any instant according to the bit sequences. Decoding can be viewed as separate phase coherent decoding of each bit stream, or, equivalently, as a mapping of the quadrature waveforms into M-fold vector estimates of the bit sequences. It is shown that the entire modulation and demodulation can be conveniently viewed in terms of signal vectors in two-dimensional signal space, where the advantages of the various encoding formats are clearly depicted. Performance results for the case M = 3 are presented.
- Publication:
-
Numerical Transmission by Cable, Vol. 1
- Pub Date:
- 1980
- Bibcode:
- 1980ntc.....1R..14A
- Keywords:
-
- Demodulation;
- Multiplexing;
- Phase Shift Keying;
- Quadratures;
- Signal Encoding;
- Single Channel Per Carrier Transmission;
- Frequency Modulation;
- Phase Modulation;
- Signal Transmission;
- Transmitters;
- Communications and Radar