Communications system having multiple spread carriers and associated methods
A communications system may include a transmitter having spreading stages configured to spread a common modulated baseband input data stream based upon respective coefficient sequences; a plurality of upconverters, each having a different frequency; and an RF output stage that generates an RF output signal. A receiver may include an RF input stage that receives an RF input signal, a plurality of downconverters, a plurality of despreading stages, and a demodulator coupled to the despreading stages.
1. A communications system comprising:
a transmitter comprising
a modulator configured to receive input data and copy the input data into a plurality of common modulated baseband input data streams, each having the same input data,
a plurality of spreading stages configured to spread the common modulated baseband input data streams based upon respective coefficient sequences,
a plurality of upconverters, each upconverter coupled to a respective spreading stage, and each upconverter having a different frequency, and
an RF output stage coupled to the plurality of upconverters to generate an RF output signal, wherein the RF output stage comprises a plurality of digital-to-analog converters (DACs) coupled to the plurality of upconverters, a combiner coupled to the plurality of DACs, and another upconverter coupled to the combiner; and
a receiver comprising
an RF input stage configured to receive an RF input signal,
a plurality of downconverters coupled to the RF input stage,
a plurality of despreading stages, each despreading stage coupled to a respective downconverter, and
a demodulator coupled to the plurality of despreading stages.
2. The communications system of claim 1 wherein each of the spreading stages operates using a common spreading sequence.
3. The communications system of claim 1 wherein each of the spreading stages operates using a different spreading sequence.
4. The communications system of claim 1 wherein the different operating frequencies of the plurality of upconverters are configured to generate a plurality of carriers, each with a guard band associated therewith.
5. The communications system of claim 1 wherein the RF input stage comprises an RF downconverter and a plurality of analog-to-digital converters (ADCs) coupled thereto.
6. The communications system of claim 1 wherein the demodulator is configured to perform a demodulation and time alignment upstream of the demodulation.
7. The communications system of claim 1 wherein the transmitter and receiver are collocated.
8. The communications system of claim 1 wherein the transmitter and receiver are spaced apart from one another.
9. The communications system of claim 1 wherein the receiver is configured to send a transmitter control signal based upon channel availability.
10. A transmitter comprising:
a modulator configured to receive input data and copy the input data and output a plurality of common modulated baseband input data streams, each having the same input data;
a plurality of spreading stages configured to spread the common modulated baseband input data streams based upon respective coefficient sequences;
a plurality of upconverters, each upconverter coupled to a respective spreading stage, and each upconverter having a different frequency; and
an RF output stage coupled to the plurality of upconverters to generate an RF output signal, wherein the RF output stage comprises a plurality of digital-to-analog converters (DACs) coupled to the plurality of upconverters, a combiner coupled to the plurality of DACs, and another upconverter coupled to the combiner.
11. The transmitter of claim 10 wherein each of the spreading stages operates using a common spreading sequence.
12. The transmitter of claim 10 wherein each of the spreading stages operates using a different spreading sequence.
13. The transmitter of claim 10 wherein the different operating frequencies of the plurality of upconverters are configured to generate a plurality of carriers, each with a guard band associated therewith.
14. A method of operating a transmitter comprising:
copying within a modulator input data into a plurality of common modulated baseband input data streams each having the same input data;
spreading with a plurality of spreading stages the common modulated baseband input data streams based upon respective coefficient sequences;
upconverting the baseband input data streams with a plurality of upconverters, each upconverter coupled to a respective spreading stage, and each upconverter having a different frequency;
converting the upconverted baseband input data streams by a plurality of digital-to-analog converters; and
generating an RF output signal with an RF output stage coupled to the plurality of digital-to-analog converters by combining multiple RF carriers within a combiner coupled to the plurality of digital-to-analog converters and upconverting the combined multiple RF carriers within an upconverter coupled to the combiner.
15. The method of claim 14 comprising operating each of the spreading stages using a common spreading sequence.
16. The method of claim 14 comprising operating each of the spreading stages using a different spreading sequence.
17. The method of claim 14 wherein the different operating frequencies of the plurality of upconverters are configured to generate a plurality of carriers, each with a guard band associated therewith.