# US 2018/0019791 A1 · Digital to analog converter apparatus, system, and method with quantization noise that is independent of an input signal

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- Number: US 2018/0019791 A1
- Document ID: US20180019791A1
- Status: Published application
- Kind: A1
- Application number: 15/212,151
- Filed: 2016-07-15
- Published: 2018-01-18
- Earliest claimed: 2016-07-15
- Assignees: Futurewei Technologies, Inc.
- Applicants: Futurewei Technologies, Inc.
- Inventors: Arkady Molev Shteiman; Xiao-Feng Qi
- Web page: https://patentgrep.com/patent/US20180019791A1

## CPC

- H04B 7/0421: {utilizing implicit feedback, e.g. steered pilot signals}
- H03M 1/0641: {the dither being a random signal}
- H03M 1/0854: {of quantisation noise}
- H04B 1/0483: {Transmitters with multiple parallel paths}
- H04B 7/0842: {Weighted combining}
- H03M 1/66: Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence)
- H04B 7/0617: {for beam forming}
- H04B: TRANSMISSION
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

An apparatus, system, and method are provided for affording digital to analog converter (DAC) quantization noise that is independent of an input signal. In operation, an input signal for a DAC is received. Further, a particular signal is added to the input signal for the DAC, such that an output signal of the DAC includes quantization noise that is independent of the input signal (e.g. includes white noise, etc.), as a result of the particular signal being added to the input signal for the DAC.

## Claims

### Claim 1

An apparatus, comprising:
a plurality of antennas;
a plurality of supporting circuitry coupled to the plurality of antennas,
wherein each of the supporting circuitry comprises:
a combiner that receives an input signal and combines the input signal with a particular signal for at least one of a plurality of antennas of a multiple-input-multiple-output (MIMO) system; and
a digital to analog converter coupled to the combiner, wherein the digital to analog converter receives the combined signal from the combiner and outputs an output signal, wherein the output signal comprises a quantization noise that is independent of the input signal;
wherein the particular signal for each of the combiners is generated utilizing a single random signal generator.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein each of the supporting circuitry further comprises:
a filter coupled to the digital to analog converter that filters the quantization noise from the output signal.

### Claim 3 (depends on 1)

The apparatus of claim 1,
wherein the random signal generator is coupled to each of the combiners for use in generating the particular signal for each of the combiners.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein the random signal generator has a uniform distribution.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the combiner adds the input signal with the particular signal.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the combiner multiplies the input signal with the particular signal.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein each of the supporting circuitry further comprises:
a steering module circuitry that is coupled to the combiner for controlling the combining of the input signal with the particular signal.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein the digital to analog converter is a single bit digital to analog converter.

### Claim 9

A multiple-input-multiple-output (MIMO) system, comprising:
a plurality of antennas coupled to a plurality of supporting circuitry, wherein each of the supporting circuitry comprises:
a combiner that receives an input signal and combines the input signal with a particular signal, and
a digital to analog converter coupled to the combiner, wherein the digital to analog converter receives the combined signal from the combiner and outputs an output signal, wherein the output signal comprises a quantization noise that is independent of the input signal;
wherein the MIMO system is configured such that the particular signal for each of the plurality of combiners of the MIMO system is generated by a single random signal generator.

### Claim 10 (depends on 9)

The MIMO system of claim 9, wherein each of the supporting circuitry further comprises:
a radio frequency transceiver coupled to the digital to analog converter for emitting a radio frequency signal based on the output signal.

### Claim 11 (depends on 9)

The MIMO system of claim 9, wherein the MIMO system is a massive MIMO system.

### Claim 12

(canceled)

### Claim 13

(canceled)

### Claim 14 (depends on 9)

The MIMO system of claim 9, wherein the MIMO system is configured such that each particular signal for each of the plurality of combiners has a different phase.

### Claim 15 (depends on 9)

The MIMO system of claim 9, wherein each of the supporting circuitry further comprises:
circuitry associated with a steering module that is coupled to the combiner for controlling the combining of the input signal with the particular signal.

### Claim 16 (depends on 15)

The MIMO system of claim 15, wherein an output of the steering module produces a signal characterized by the following equation:
Steering(m, α)=exp (j·π·m·sin(α)), where:
Steering(m, α) is a steering function towards direction α at antenna m, where m>0;
sin( )is a sine function;
exp(j*x)=cos(x)+j*sin(x);
j is complex 1; and
α is a steering direction.

### Claim 17 (depends on 16)

The MIMO system of claim 16, wherein the output signal is characterized by the following equation:
y(m, n)=DACm(Steering(m,α)·x(n)), where:
y(m,n) is a DAC m output signal at time n, where m>0; and
x(n) is a signal sent towards direction α.

### Claim 18

A method for processing signals in a multiple-input-multiple-output (MIMO) system comprising a plurality of antennas coupled to a plurality of supporting circuitry, comprising:
receiving an input signal for a digital to analog converter in each of the plurality of supporting circuitry;
combining the input signal with a particular signal; wherein the particular signal for each of the plurality of antennas of the MIMO system is generated by a single random signal generator;
transmitting the combined signal to the digital to analog converter; and
outputting an output signal from the digital to analog converter that includes quantization noise that is independent of the input signal.

### Claim 19

(canceled)

### Claim 20 (depends on 18)

The method of claim 18, wherein the particular signal is white noise.

### Claim 21 (depends on 18)

The method of claim 18, wherein the particular signal is uniformly distributed.

### Claim 22 (depends on 18)

The method of claim 18, wherein the quantization noise is independent, identically distributed (IID).

### Claim 23 (depends on 18)

The method of claim 18, wherein the quantization noise is random quantization noise.

### Claim 24 (depends on 18)

The method of claim 18, and further comprising filtering the quantization noise of the output signal of the digital to analog converter.