Method and Apparatus for Real Time Multiplexing with Transmitter and Antenna Array Elements

• US 20110299441A1
• Filed: 09/24/2010
• Published: 12/08/2011
• Est. Priority Date: 06/07/2010
• Status: Active Grant

• Current Assignee: MaxLinear Communications, LLC (f/k/a Entropic Communications, LLC) (Maxlinear Incorporated)
• Original Assignee: Entropic Communications Incorporated (Maxlinear Incorporated)
• Inventors: PETROVIC, Branislav
• Granted Patent: US 10,050,680 B2
• Time in Patent Office: Days
• US Class Current: 370/310
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method of signal processing, or corresponding apparatus, includes providing digital input signals representing beamforming data to be transmitted on respective antennas. One of the digital input signals is selected at a time among a plurality of times, to cycle through the digital input signals repeatedly and provide a multiplexed digital signal, which is converted to a multiplexed analog signal. The multiplexed analog signal is filtered to pass a predetermined frequency band and demultiplexed to provide analog output signals. One of the analog output signals is selected and provided to a corresponding antenna for transmission. Sharing a transmitter and DAC among multiple antennas results in reduced cost and power. Such cost and power reductions in turn enable larger antenna arrays than are available with prior art techniques, thereby promoting increased throughput and coverage.

Claims

1. A method comprising:

a) receiving a plurality of digital input signals representing beamforming data, the digital signals comprising data samples;

b) multiplexing the digital input signals to output a multiplexed digital signal;

c) converting the multiplexed digital signal into a multiplexed analog signal;

d) demultiplexing the multiplexed analog signal to provide a plurality of analog output signals;

e) selecting each of the analog output signals in turn; and

f) coupling each selected analog output signal to a corresponding one of a plurality of antenna elements for transmission.

2. The method of claim 1, further comprising controlling a gain of the multiplexed analog signal automatically to ensure correct signal strength of each antenna element.

3. The method of claim 2, wherein multiplexing the digital input signals is synchronized with the controlling of the gain of the multiplexed analog signal.

4. The method of claim 1, further comprising upconverting the multiplexed analog signal to an output frequency prior to demultiplexing.

5. The method of claim 1, further comprising:

a) interpolating data samples to determine a sample value at an offset time.

6. The method of claim 5, wherein the data samples are offset in time relative to one another by non-uniform time offsets.

7. The method of claim 1, wherein coupling each selected analog signal comprises electrically terminating only the antenna element corresponding to the selected analog output signal, and disconnecting the other antenna elements.

8. The method of claim 1, wherein multiple samples of one of the digital input signals are consecutively converted to analog before a next one of the digital input signal is selected.

9. A communication apparatus comprising:

a) a digital processing module comprising a multiplexer that;

i) selects one of a plurality of digital input signals, representing beamforming data, one at a time; and

ii) outputs a multiplexed digital signal based on the selection among the digital input signals;

b) a transmitter comprising;

i) a digital to analog converter (DAC) configured to convert the multiplexed digital signal to a multiplexed analog signal, and

ii) a bandpass filter configured to filter the multiplexed analog signal by passing a predetermined frequency band;

c) a demultiplexer configured to demultiplex the multiplexed analog signal to provide a plurality of analog output signals; and

d) a plurality of antennas configured to transmit respective ones of the plurality of analog output signals.

10. The apparatus of claim 9, wherein the transmitter further comprises a gain controller configured to automatically adjust a gain of the multiplexed analog signal to account for a threshold signal strength of each antenna.

11. The apparatus of claim 9, wherein the transmitter further comprises a mixer and a local oscillator, the mixer configured to upconvert the multiplexed analog signal to an output frequency prior to demultiplexing.

12. The apparatus of claim 9, wherein the digital processing module further comprises:

a) a digital signal processor configured to align antenna data samples corresponding to respective antennas to a determined time; and

b) an interpolator configured to interpolate the aligned antenna data samples to provide the digital input signals at respective ones of the plurality of times.

13. The apparatus of claim 9, wherein the digital processing module further comprises a digital signal processor configured to modulate data samples, corresponding to respective antennas, in phase and amplitude to perform multiple input multiple output (MIMO) spatial multiplexing and beamforming and provide the digital input signals at respective ones of the plurality of times.

14. A communication apparatus comprising:

a) a digital processing module comprising a multiplexer that;

i) selects, one at a time, a plurality of digital input signals representing beamforming data; and

ii) outputs a multiplexed digital signal based on the selection among the digital input signals;

b) a transmitter comprising a digital to analog converter (DAC) configured to convert the multiplexed digital signal to a multiplexed analog signal;

c) a demultiplexer configured to demultiplex the multiplexed analog signal to provide a plurality of analog output signals;

d) a plurality of filters, each filter receiving one of the analog output signals and outputting a filtered analog output signal; and

e) a plurality of antenna elements, each coupled to a corresponding one of the plurality of filters, each antenna element transmitting the filtered analog output signal output by the corresponding filter.

15. The apparatus of claim 14, wherein the transmitter further comprises a bandpass filter which receives the multiplexed analog signal, the bandpass filter of the transmitter having a bandwidth wider than the product of the number of antennas and the bandwidth of one of the plurality of filters.

16. A communication apparatus comprising:

a) a digital processing module comprising a plurality of multiplexers, wherein each multiplexer;

i) selects, one at a time, a digital input signal from among a unique plurality of digital input signals received by each multiplexer; and

ii) outputs a multiplexed digital signal based on the selection of the digital input signals;

b) a plurality of transmitters, each transmitter comprising;

i) a digital to analog converter (DAC) associated with a corresponding one of the multiplexed digital signals, the DAC converting the corresponding multiplexed digital signal to a multiplexed analog signal, and

ii) a bandpass filter associated with a corresponding multiplexed digital signal, the bandpass filter filtering the corresponding multiplexed analog signal;

c) a plurality of demultiplexers, each demultiplexer configured to demultiplex a corresponding multiplexed analog signal to provide a group of analog output signals among a plurality of groups of analog output signals; and

d) a plurality of antennas grouped into multiple antenna array, each antenna array comprising multiple antenna elements, the antennas configured to transmit respective ones of a corresponding group of analog output signals.

17. The apparatus of claim 16, wherein the digital processing module further comprises:

a) a digital signal processor configured to align antenna data samples corresponding to respective antennas to a determined time; and

b) an interpolator configured to interpolate the aligned antenna data samples to provide the groups of digital input signals, the digital input signals of each group provided at respective ones of the plurality of times.