Method for signal transmission using spectrally efficient orthogonal modulation
First Claim
1. A method for digital signal transmission, comprising the steps of:
- encoding in each of N symbols a plurality of data bits under a conventional coding scheme;
modulating each of said N symbols for a predetermined time interval onto a corresponding one of N substantially band limited finite duration orthogonal waveforms;
summing each of said N modulated waveforms, aligned in time, to obtained a summed waveform;
modulating said summed waveform for said predetermined time interval onto a carrier signal; and
transmitting said modulated summed waveform in a communication channel.
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Accused Products
Abstract
A structure and a method for transmitting digital data modulate the amplitude and the phase of a set of orthogonal band-limited finite duration waveforms. In one embodiment, a group of information symbols modulate in parallel a set of spectrally efficient orthogonal waveforms, known as prolate spheroidal wave functions. The modulated orthogonal waveforms are summed, and the resulting composite signal then modulates a carrier signal for transmission. The compressed spectrum modulated signal provides a robust data waveform which reduces the spectral bandwidth requirements compared to digital modulation formats employed in the prior art. The transmitter and the receiver for modulating and demodulating the orthogonal waveforms for transmission operate at slower speeds than corresponding equipment of existing modulation schemes of comparable symbol rate. Consequently, both simplicity of design and cost savings are realized in a compressed spectrum modulation scheme.
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Citations
23 Claims
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1. A method for digital signal transmission, comprising the steps of:
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encoding in each of N symbols a plurality of data bits under a conventional coding scheme; modulating each of said N symbols for a predetermined time interval onto a corresponding one of N substantially band limited finite duration orthogonal waveforms; summing each of said N modulated waveforms, aligned in time, to obtained a summed waveform; modulating said summed waveform for said predetermined time interval onto a carrier signal; and transmitting said modulated summed waveform in a communication channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A circuit for digital signal transmission, comprising:
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an encoder encoding in each of N symbols a plurality of data bits under a conventional coding scheme; a plurality of first modulating circuits, each first modulating circuit modulating one of said N symbols for a predetermined time interval onto a corresponding one of N substantially band-limited finite duration orthogonal waveforms; a summing circuit, coupled to receive each of said N modulated waveforms, for obtaining a summed waveform; a second modulating circuit, coupled to receive said summed waveform, for modulating said summed waveform for said predetermined time interval onto a carrier signal; and a transmitter circuit, coupled to receive said said modulated summed waveform, for transmitting said summed waveform in a communication channel. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification