Array amplitude modulation system and method
Array amplitude modulation which includes mapping a data symbol to a phase modulation signal and an amplitude modulation signal for transmission from antenna elements; applying the phase modulation signal to the antenna element amplifiers; and generating a pattern of enabling/disabling the antenna element amplifiers as a function of the amplitude modulation to produce a phase and amplitude modulated transmission from the antenna elements.
1. An array amplitude modulation system comprising:
a mapping circuit for mapping a data symbol to a phase modulation signal and an amplitude modulation signal;
a plurality of antenna elements;
an amplifier associated with each antenna element, each amplifier having fixed amplification; and
a control circuit responsive to said amplitude modulation signal to selectively enable/disable said amplifiers to produce a phase and amplitude modulation transmission from said antenna elements, the selectively enabling/disabling respectively turning on/off said amplifiers.
2. The array amplitude system of claim 1 in which said amplifiers include non-linear amplifiers.
3. The array amplitude system of claim 1 in which said control circuit includes a pattern generator for identifying the amplifiers to be selectively enabled/disabled.
4. The array amplitude system of claim 3 in which said control circuit includes a switching circuit responsive to said pattern generator circuit for selectively enabling/disabling identified amplifiers.
5. The array amplitude system of claim 3 in which said pattern generator includes a look-up table.
6. The array amplitude system of claim 3 in which said pattern generator generates a random pattern of amplifier enabling/disabling.
7. The array amplitude system of claim 3 in which said pattern generator generates a regular pattern of amplifier enabling/disabling.
8. The array amplitude system of claim 7 in which said regular pattern includes an interleaved pattern.
9. The array amplitude system of claim 7 in which said regular pattern includes a peripheral pattern of amplifier enabling/disabling.
10. The array amplitude system of claim 9 in which said peripheral pattern includes an outer diameter pattern.
11. The array amplitude system of claim 1 further including a custom modulator for generating a custom amplitude modulation signal shifted relative to said amplitude modulation signal and a matching custom demodulation scheme for demodulating the custom modulation.
12. The array amplitude system of claim 11 in which said custom modulator and/or demodulator is responsive to a small array quantizing error input to adjust for small array quantizing error.
13. The array amplitude system of claim 11 in which said custom modulator and/or demodulator is responsive to a steering error input to adjust for steering error.
14. A method of array amplitude modulation comprising:
mapping a data symbol to a phase modulation signal and an amplitude modulation signal for transmission from antenna elements, the antenna elements each associated with a single amplifier having fixed amplification;
applying the phase modulation signal to the antenna element amplifiers; and
generating a pattern of enabling/disabling the antenna element amplifiers as a function of the amplitude modulation to produce a phase and amplitude modulated transmission from the antenna elements, wherein the enabling/disabling respectively turns on/off the amplifiers.
15. The method of array amplitude modulation of claim 14 in which said amplifiers are nonlinear amplifiers.
16. The method of array amplitude modulation of claim 14 in which said patterns include random and regular.
17. The method of array amplitude modulation of claim 16 in which said regular patterns include interleaved, peripheral, and outer diameter.
18. The method of array amplitude modulation of claim 14 further includes generating a custom amplitude modulation signal shifted relative to the amplitude modulation signal.
19. The method of array amplitude modulation of claim 18 in which the custom amplitude modulation signal is generated in response to a small array quantizing error signal.
20. The method of array amplitude modulation of claim 18 in which the custom amplitude modulation signal is generated in response to a steering error signal.
21. The array amplitude modulation system of claim 1 in which the phase modulation signal is normalized and in which the control circuit is configured to send the normalized phase modulation signal to each antenna element.
22. The method of claim 14 further comprising mapping the data symbol to a normalized phase modulation signal.