Interference reduction for multiple signals
The present invention reduces the degradation in performance of one or more radio signals that are co-transmitted with a first radio signal from the same transmitting antenna in the same frequency channel and received by the same antenna due to multipath or other shared interference, where the one or more radio signals can be separated from the first radio signal. All received signals are coupled to the same adaptive array or adaptive filter to reduce multipath or other shared interference of the first radio signal, which reduces multipath and other shared interference in the other radio signals before they are separated and processed by their respective receivers, or the individual radio signals are separated before the first signal enters the adaptive array and coupled to a slave weighting network slaved to the weights of the adaptive array of the first signal to reduce interference in all the signals.
1. A method for using one adaptive array for reducing interference of at least two received signals, the method comprising the steps of:
a. deriving at least two input signals of the one adaptive array from the at least two received signals, the at least two received signals were transmitted from at least one transmit antenna of a common transmitter end in a common frequency channel, the transmitted signals were formed by transmitting an at least one first signal and an at least one second signal,
b. generating an adaptive array output signal of the adaptive array made up of the at least one first signal and the at least one second signal with reduced interference, wherein the adaptive array is designed to reduce interference in the at least one first signal, and
c. retrieving one or more of the at least one first signal and the at least one second signal from the adaptive array output signal.
2. A method as in claim 1 , wherein the reducing of the interference of the at least one first signal by the adaptive array is carried out using propagation characteristics of at least one of the at least one first signal.
3. A method as in claim 1 , wherein the at least two received signals include at least one training signal, so that the adaptive array reduces the interference of the at least one first signal using one or more of the at least one training signal.
4. A method as in claim 1 , wherein the at least one first signal includes at least one training signal, so that the adaptive array reduces the interference of the at least one first signal using one or more of the at least one training signal.
5. A method as in claim 1 , wherein the at least one first signal and the at least one second signal are at least part of a common multi-carrier signal.
6. A claim as in claim 5 , wherein the common multi-carrier signal includes an orthogonal frequency division multiplex signal.
7. A method as in claim 1 , wherein the receiving adaptive array includes a digital processor, and wherein the adaptive array reduces the interference of the at least one first signal using the digital processor.
8. A method as in claim 1 , wherein the interference is a result of multipath.
9. Apparatus for reducing interference in at least two received signals, the apparatus comprising:
an adaptive array with at least two input signals configured to generate an adaptive array output signal, the at least two input signals are derived from the at least two received signals that were transmitted from one or more transmit antennas at a common transmitter end in a common frequency channel, the transmitted signals were formed by transmitting an at least one first signal and an at least one second signal, the adaptive array output signal is made up of the at least one first signal and the at least one second signal with reduced interference, wherein the adaptive array is designed to reduce interference in the at least one first signal, and
at least one separator to retrieve one or more of the at least one first signal and the at least one second signal from the adaptive array output signal.
10. Apparatus as in claim 9 , wherein the adaptive array reduces the interference of the at least one first signal using propagation characteristics of one or more of the at least one first signal.
11. Apparatus as in claim 9 , wherein the at least two received signals include at least one training signal, so that the adaptive array reduces the interference of the at least one first signal using one or more of the at least one training signal.
12. Apparatus as in claim 9 , wherein the at least one first signal includes at least one training signal, so that the adaptive array reduces the interference in the at least one first signal using one or more of the at least one training signal.
13. Apparatus as in claim 9 , wherein the at least one first signal and the at least one second signal are at least part of a common multi-carrier signal.
14. Apparatus as in claim 13 , wherein the common multi-carrier signal includes an orthogonal frequency division multiplex signal.
15. Apparatus as in claim 9 , wherein the apparatus includes a digital processor, and wherein the adaptive array reduces the interference in the at least one first signal using the digital processor.
16. Apparatus as in claim 9 , wherein the interference is a result of multipath.
17. Apparatus for reducing interference in K received signals, the apparatus comprising:
an adaptive array with at least K input signals configured to generate L adaptive array output signals, the at least K input signals are derived from the K received signals that were each transmitted from a separate one of K transmit antennas at a common transmitter end in a common frequency channel, the K transmitted signals were formed by transmitting L signals, L is at least 2, K is at least L, the L signals are each made up of a different one of an L at least one first signals and an L at least one second signals, the L adaptive array output signals are each separately made up of the associated different one of the L at least one first signals and the L at least one second signals with reduced interference, wherein the adaptive array is designed to reduce interference in the L at least one first signals, and
at least one separator to retrieve one or more of the L at least one first signals and the L at least one second signals from one or more of the L adaptive array output signals.
18. Apparatus as in claim 17 , wherein K=L, each one of the L signals was transmitted from an associated different one of the K transmit antennas.
19. Apparatus as in claim 17 , wherein each of the L signals includes a different one of L representations of a common at least one first signal and a common at least one second signal.