MULTI-ANTENNA BEAM-FORMING SYSTEM FOR TRANSMITTING CONSTANT ENVELOPE SIGNALS DECOMPOSED FROM A VARIABLE ENVELOPE SIGNAL

• US 20100149039A1
• Filed: 10/05/2009
• Published: 06/17/2010
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Rambus Inc.
• Inventors: Abbasfar, Aliazam, Komijani, Abbas
• Granted Patent: US 8,482,462 B2
• Time in Patent Office: Days
• US Class Current: 342/377
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Embodiments in the present disclosure pertain to a multi-antenna beam-forming system for transmitting constant envelope signals decomposed from a variable envelope signal. The variable envelope signal is decomposed into two constant envelope signals. Each of the constant envelope signals are separately amplified by power amplifiers and transmitted over separate antennas. Beam steering delays can be added to the transmit paths of the constant envelope signals to direct the beam to the location of a receiver. The transmitted constant envelope signals combine through spatial out-phasing such that a receiving antenna receives a variable envelope signal.

Claims

1. A transmitter circuit comprising:

a circuit for decomposing a variable envelope signal into at least a first constant envelope signal and a second constant envelope signal;

a first amplifier coupled to the circuit for decomposing the variable envelope signal, wherein the first amplifier amplifies the first constant envelope signal;

a first antenna coupled to the first amplifier that transmits an amplified first constant envelope signal;

a second amplifier coupled to the circuit for decomposing the variable envelope signal, wherein the second amplifier amplifies the second constant envelope signal;

a second antenna coupled to the second amplifier that transmits an amplified second constant envelope signal.

2. The transmitter circuit of claim 1 further comprising at least one delay circuit that delays the second constant envelope signal by a specified amount of time such that a variable envelope signal results from the superposition of the first and second envelope signals at a location of a receiver antenna.

3. The transmitter circuit of claim 2, wherein the delay circuit comprises at least one mixer which adds a phase delay to a transmit path of one of the first constant envelope signal and the second constant envelope signal.

4. The transmitter circuit of claim 1 further comprising:

at least three delay circuits for delaying the first constant envelope signal and the second constant envelope signal to steer a beam to a location of a receiver antenna;

at least four amplifiers for amplifying the first constant envelope signal and the second constant envelope signal;

at least four antennas for transmitting the first constant envelope signal and the second constant envelope signal.

5. The transmitter circuit of claim 1, wherein the first constant envelope signal and the second constant envelope signal have phases that when transmitted as RF signals, a receiving antenna receives the variable envelope signal.

6. The transmitter circuit of claim 1, wherein the first amplifier and the second amplifier comprise power amplifiers operating in saturation.

7. A method for transmitting RF signals comprising:

generating a first signal having constant amplitude and varying phase;

amplifying the first signal;

transmitting the first signal wirelessly;

generating a second signal having constant amplitude and varying phase;

amplifying the second signal;

transmitting the second signal wirelessly, wherein the first signal and the second signal are decomposed from a third signal that has variable amplitude and variable phase.

8. The method of claim 7 further comprising:

adding a delay to the second signal, wherein the delay is added to transmit the first signal and the second signal to a known location of a receiver.

9. The method of claim 7 further comprising:

adding a plurality of delays to a plurality of transmit paths for transmitting the first signal and the second signal in a phased array antenna system.

10. The method of claim 7 further comprising:

amplifying the first signal at saturation of a first power amplifier;

amplifying the second signal at saturation of a second power amplifier.

11. The method of claim 7 further comprising:

spatially out-phasing the third signal, wherein the first signal and the second signal wirelessly combine so that a receiver receives a wireless signal with varying amplitude and varying phase.

12. A method for wirelessly transmitting a signal comprising:

decomposing a variable envelope signal into a first constant envelope signal and a second constant envelope signal;

amplifying the first constant envelope signal;

transmitting an amplified first constant envelope signal wirelessly over a first antenna;

amplifying the second constant envelope signal;

transmitting an amplified second constant envelope signal wirelessly over a second antenna.

13. The method of claim 12 further comprising:

adding beam steering delays to direct a beam to a location of a receiver antenna.

14. The method of claim 12 further comprising:

spatially out-phasing the variable envelope signal, wherein the first constant envelope signal and the second constant envelope signal combine through superposition as RF signals in order to produce an RF signal corresponding to the variable envelope signal.

15. A multi-antenna system for transmitting constant envelope signals decomposed from a variable envelope signal comprising:

a processor for generating the variable envelope signal having varying amplitudes and varying phases;

an out-phasing decomposition circuit coupled to the processor that generates at least a first constant envelope signal and a second constant envelope signal, wherein the first constant envelope signal and the second constant envelope signal have constant amplitudes and varying phases which together represent the variable envelope signal;

a first power amplifier coupled to the out-phasing decomposition circuit that amplifies the first constant envelope signal;

a first antenna coupled to the first power amplifier for wireless transmission of the first constant envelope signal;

a second power amplifier coupled to the out-phasing decomposition circuit that amplifies the second constant envelope signal;

a second antenna coupled to the second power amplifier wireless transmission of the second constant envelope signal.

16. The multi-antenna system of claim 15 further comprising:

a plurality of delay circuits coupled to the out-phasing decomposition circuit for adding beam steering delays to transmit paths of the first constant envelope signal and the second constant envelope signal;

a plurality of power amplifiers coupled to the plurality of delay circuits for amplifying delayed first constant envelope signals and delayed second constant envelope signals;

a plurality of antennas for wireless transmission of amplified, delayed first constant envelope signals and second constant envelope signals.

17. The multi-antenna system of claim 16, wherein the plurality of delay circuits include a plurality of adders for adding the delays to the first constant envelope signals and the second constant envelope signals.

18. The multi-antenna system of claim 16, wherein the plurality of delay circuits, plurality of power amplifiers, and plurality of antennas comprise a phased-array antenna system that electronically steers a beam to a location of a receiver.

19. The multi-antenna system of claim 15, wherein the wireless transmission of the first constant envelope signal and the wireless transmission of the second constant envelope signal combine as RF signals.

20. The multi-antenna system of claim 15, wherein the wireless transmission of the first constant envelope signal and the wireless transmission of the second constant envelope signal is capable of being received by a variable envelope signal receiver.

21. The multi-antenna system of claim 15, wherein the wireless transmission of the first constant envelope signal and the wireless transmission of the second constant envelope signal establishes point-to-point communications with a receiver.