System and method for controlling combined radio signals
A method for controlling a combined waveform, representing a combination of at least two signals having orthogonal frequency multiplexed signal components, comprising: receiving information defining the at least two signals; transforming the information defining each signal to a representation having orthogonal frequency multiplexed signal components, such that at least one signal has at least two alternate representations of the same information, and combining the transformed information using the at least two alternate representations, in at least two different ways, to define respectively different combinations; analyzing the respectively different combinations with respect to at least one criterion; and outputting a respective combined waveform or information defining the waveform, representing a selected combination of the transformed information from each of the at least two signals selected based on the analysis.
1. A radio transmitter, comprising:
at least one input port configured to receive information defining at least two orthogonal frequency division multiplexed (OFDM) signals, each having OFDM components within OFDM subchannels of a respective separate OFDM channel, each respective OFDM signal being compliant with an OFDM signal communication protocol, such that an OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signal;
at least one automated processor, configured to:
define at least two alternate combinations of the at least two OFDM signals occupying the separate OFDM channels, each alternate combination having the OFDM components within the respective OFDM subchannels of the respective separate OFDM channels, each of the at least two OFDM signals within each of the at least two alternate combinations of the at least two OFDM signals being compliant with the OFDM signal communication protocol, such that the OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signals of each respective alternate combination without side information outside of the OFDM signal communication protocol; and
select one of the alternate combinations of the at least two OFDM signals based on at least one selection criteria; and
an output port configured to supply the selected one of the alternate combinations of the at least two OFDM signals to a power amplifier, modulated at a radio frequency, for transmission through an antenna.
2. The radio transmitter according to claim 1 , wherein the at least two alternate combinations of the at least two OFDM signals vary with respect to a relative time displacement of the at least two OFDM signals.
3. The radio transmitter according to claim 2 , wherein the at least one selection criteria comprises a peak level.
4. The radio transmitter according to claim 2 , wherein the at least one selection criteria comprises a peak to average power ratio.
5. The radio transmitter according to claim 2 , wherein the at least one selection criteria comprises an estimate of distortion from the power amplifier.
6. The radio transmitter according claim 1 , wherein the OFDM signal communication protocol is compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol.
7. The radio transmitter according to claim 1 , wherein the at least two alternate combinations of the at least two OFDM signals differ respectively in a cyclic time shift of one OFDM signal with respect to another OFDM signal.
8. The radio transmitter according to claim 1 , further comprising a computational model of at least the power amplifier, wherein the selection criteria comprises an evaluation of a modelled performance of at least the power amplifier based on the computational model.
9. The radio transmitter according to claim 1 , further comprising a predistorter configured to predistort the selected one of the alternate combinations of the at least two OFDM signals.
10. A radio frequency transmitter, comprising:
an input port configured to receive at least two orthogonal frequency division multiplexed (OFDM) signals, each having OFDM components within OFDM subchannels of a respective separate OFDM channel, each respective OFDM signal being compliant with an OFDM signal communication protocol, such that an OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signal;
a processor configured to define at least two alternate combinations of the at least two OFDM signals occupying the separate OFDM channels, each alternate combination having the OFDM components within the respective OFDM subchannels of the respective separate OFDM channels, each of the at least two OFDM signals within each of the at least two alternate combinations of the at least two OFDM signals being compliant with the OFDM signal communication protocol, such that the OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signals of each respective alternate combination without side information outside of the OFDM signal communication protocol, and to select one of the alternate combinations of the at least two OFDM signals based on at least one selection criteria; and
an output port configured to communicate the selected one of the alternate combinations of the at least two OFDM signals.
11. The radio frequency transmitter according to claim 10 , further comprising a power amplifier subject to non-linear distortion of combinations of OFDM signals, configured to receive the selected one of the alternate combinations of the at least two OFDM signals from the output port.
12. The radio frequency transmitter according to claim 11 , wherein the at least one selection criteria comprises an estimate of distortion from the power amplifier.
13. The radio frequency transmitter according to claim 11 , further comprising a computational model of at least the power amplifier, wherein the selection criteria comprises an evaluation of a modelled performance of at least the power amplifier based on the computational model.
14. The radio frequency transmitter according to claim 10 , further comprising a predistorter configured to predistort the selected one of the alternate combinations of the at least two OFDM signals.
15. The radio frequency transmitter according to claim 10 , wherein the at least two alternate combinations of the at least two OFDM signals vary with respect to a relative time displacement of the at least two OFDM signals.
16. The radio frequency transmitter according to claim 10 , wherein the at least two alternate combinations of the at least two OFDM signals vary with respect to a relative cyclic time shift between the at least two OFDM signals.
17. The radio frequency transmitter according to claim 10 , wherein the at least one selection criteria comprises a peak level of the alternate combinations of the at least two OFDM signals.
18. The radio frequency transmitter according to claim 10 , wherein the at least one selection criteria comprises a peak to average power ratio of the alternate combinations of the at least two OFDM signals.
19. The radio frequency transmitter according claim 10 , wherein the OFDM signal communication protocol is compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol.
20. A method of transmitting a combined signal, comprising:
receiving at least two orthogonal frequency division multiplexed (OFDM) signals, each having OFDM components within OFDM subchannels of a respective separate OFDM channel, each respective OFDM signal being compliant with an OFDM signal communication protocol, such that an OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signal;
defining at least two alternate combinations of the at least two OFDM signals occupying the separate OFDM channels varying from each other by an amount of a relative time shift of the respective OFDM signals, each alternate combination having the OFDM components within the respective OFDM subchannels of the respective separate OFDM channels, each of the at least two OFDM signals within each of the at least two alternate combinations of the at least two OFDM signals being compliant with the OFDM signal communication protocol, such that the OFDM signal communication protocol compliant receiver can demodulate the respective OFDM signals of each respective alternate combination without side information outside of the OFDM signal communication protocol;
selecting one of the alternate combinations of the at least two OFDM signals based on at least one selection criteria; and
communicating the selected one of the alternate combinations of the at least two OFDM signals.