# US 2019/0356393 A1 · Constellation selection threshold adaptation for slicer

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- Number: US 2019/0356393 A1
- Document ID: US20190356393A1
- Status: Published application
- Kind: A1
- Application number: 15/984,034
- Filed: 2018-05-18
- Published: 2019-11-21
- Earliest claimed: 2018-05-18
- Assignees: MACOM Technology Solutions Holding, Inc.
- Applicants: MACOM Technology Solutions Holding, Inc.
- Inventors: Yehuda AZENKOT
- Web page: https://patentgrep.com/patent/US20190356393A1

## CPC

- H04B 10/695: {Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control}
- H04L 27/06: Demodulator circuits; Receiver circuits
- H04B 10/6971: {using equalisation}
- H04L 25/03006: {Arrangements for removing intersymbol interference}
- H04L 27/066: {Carrier recovery circuits (H04L27/2271 takes precedence)}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

System and method of adapting thresholds for constellation selection based on statistic distributions of received data symbols. To determine an adapted threshold, an expected ratio of received symbols with values in a certain range is preset based on an expected statistic distribution of data symbols across the multiple constellations. A first and a second ratios are defined based on the expected ratio, the first ratio being the expected ratio minus an error ratio and the second ratio being the expected ratio plus the error ratio. A first value is determined which makes the received symbols in a firs range to constitute the first ratio of a set of slicer inputs. A second value is determined which makes the received symbols in the second range to constitute the second ratio of a set of slicer outputs. The adapted threshold is then obtained based on the first and the second value.

## Claims

### Claim 1

A method of dynamically determining thresholds of a slicer, the method comprising:
accessing a first plurality of inputs for supply to said slicer;
comparing each of said first plurality of inputs with a first value;
based on said comparing with said first value, determining a first count ratio of first inputs to said first plurality of inputs, wherein each of said first inputs is comprised in said first plurality of inputs and has a value encompassed in a first range that is defined by said first value; and
determining a first threshold of said slicer based on said first value and said first count ratio.

### Claim 2 (depends on 1)

The method of claim 1 further comprising:
accessing a second plurality of inputs for supply to said slicer;
comparing each of said second plurality of inputs with a second value;
based on said comparing with said second value, determining a second count ratio of second inputs to said second plurality of inputs, wherein each of said second inputs is comprised in said second plurality of inputs and has a value encompassed in a second range that is defined by said second value, and
wherein said determining said first threshold is further based on said second value and said second count ratio.

### Claim 3 (depends on 2)

The method of claim 2, wherein said determining said first threshold comprises averaging said first value and said second value.

### Claim 4 (depends on 2)

The method of claim 2 further comprising determining said first value and said second value, wherein said determining said first value comprises adjusting said first value until said first count ratio equals a first nominal ratio minus a preset value, and wherein said determining said second value comprises adjusting said second value until said second count ratio equals said first nominal ratio plus said preset value.

### Claim 5 (depends on 4)

The method of claim 4, wherein said slicer is configured to use Pulse Amplitude Modulation (PAM) comprising N constellation levels, wherein said first nominal ratio equals i/N, wherein i is an integer greater than 0 and smaller than N, and wherein further said preset value is equal to or less than 5%.

### Claim 6 (depends on 4)

The method of claim 4, wherein said slicer is configured to use Quadrature Amplitude Modulation (QAM) comprising 2×N constellation levels, wherein said first nominal ratio equals
i
N
,
wherein i is an integer greater than 0 and smaller than N, and wherein further said preset value is equal to or less than 5%.

### Claim 7 (depends on 2)

The method of claim 2, wherein said first plurality and said second plurality of inputs are output from an equalizer in a receiver.

### Claim 8 (depends on 2)

The method of claim 2, wherein said first range encompasses any value below said first value, and wherein said second range encompasses any value below said second value.

### Claim 9

A device comprising:
a slicer decision unit configured to:
produce a first output value responsive to an input greater than a threshold; and
produce a second output value responsive to an input smaller than said threshold; and
a threshold adaptation unit coupled to said slicer decision unit comprising:
a comparator configured to compare each of a first plurality of inputs with a first value, wherein said first plurality of inputs are supplied to said slicer decision unit;
a first counter configured to, responsive to comparison decisions output from said comparator, produce a number of first inputs comprised in said first plurality of inputs and each having a value encompassed in a first range, wherein said first range is defined by said first value; and
logic configured to:
determine a first count ratio of said number of said first inputs to a total number of said first plurality of inputs; and
determine a first threshold of said slicer decision unit based on said first value and said first count ratio.

### Claim 10 (depends on 9)

The device of claim 9, where said threshold adaptation unit is further configured to:
access a second plurality of inputs for supply to said slicer decision unit;
compare each of said second plurality of inputs with a second value;
based on said comparison with said second value, determine a second count ratio of second inputs to said second plurality of inputs, wherein each of said second inputs is comprised in said second plurality of inputs and has a value encompassed in a second range that is defined by said second value, and
wherein said first threshold is determined further based on said second value and said second count ratio.

### Claim 11 (depends on 10)

The device of claim 10, wherein said threshold adaptation unit is further configured to average said first value and said second value to generate said first threshold for said slicer decision unit.

### Claim 12 (depends on 10)

The device of claim 10, wherein said threshold adaptation unit is further configured to:
determine said first value by varying said first value until said first count ratio equals a first nominal ratio minus a preset value; and
determine said second value by varying said second value until said second count ratio equals said first nominal ratio plus a preset value.

### Claim 13 (depends on 12)

The device of claim 12, wherein said slicer decision unit is configured to use Pulse Amplitude Modulation (PAM) comprising N constellation levels, wherein said first output value and said second output value are selected from said N constellation levels, and wherein further said first nominal ratio equals
i
N
,
wherein i is an integer greater than 0 and smaller than N, and wherein further said preset value is equal to or less than 5%.

### Claim 14 (depends on 12)

The device of claim 12, wherein said slicer is configured to use Quadrature Amplitude Modulation (QAM) comprising 2×N constellation levels, wherein said first nominal ratio equals
i
N
,
wherein i is an integer greater than 0 and smaller than N, and wherein further said preset value is equal to or less than 5%.

### Claim 15 (depends on 10)

The device of claim 10, wherein said first range encompasses any value below said first value, and wherein said second range encompasses any value below said second value.

### Claim 16

A receiver comprising:
a analog-to-digital converter (ADC) configured to converted received analog signals to digital signals;
an equalizer coupled to said ADC and configured to: generate equalized signals responsive to digital signals; and send said equalized signals as inputs to a slicer decision unit;
said slicer decision unit coupled to said equalizer and configured to:
produce a first output value responsive to an input greater than a threshold; and
produce a second output value responsive to an input smaller than said threshold; and
a threshold adaptation unit coupled to said slicer decision unit and configured to :
access a first plurality of inputs for supply to said slicer decision unit;
compare each of said first plurality of inputs with a first value;
based on comparison with said first value, determine a first count ratio of first inputs to said first plurality of inputs, wherein each of said first inputs is comprised in said first plurality of inputs and has a value encompassed in a first range that is defined by said first value;
access a second plurality of inputs for supply to said slicer;
compare each of said second plurality of inputs with a second value;
based on comparison with said second value, determine a second count ratio of second inputs to said second plurality of inputs, wherein each of said second inputs is comprised in said second plurality of inputs and has a value encompassed in a second range that is defined by said second value;
determine an adapted threshold based on said first value, second value, said first count ratio and said second count ratio; and
send said adapted threshold to said slicer decision unit.

### Claim 17 (depends on 16)

The receiver of claim 16, wherein said threshold adaptation unit is further configured to determine said adapted threshold by averaging said first value and said second value.

### Claim 18 (depends on 16)

The receiver of claim 16, wherein said threshold adaptation unit is further configured to:
determine said first value by adjusting said first value until said first count ratio equals a first nominal ratio minus a preset value; and
determine said second value by adjusting said second value until said second count ratio equals said first nominal ratio plus said preset value.

### Claim 19 (depends on 16)

The receiver of claim 16, wherein said slicer is configured to use one of Pulse Amplitude Modulation (PAM) comprising N constellation levels and Quadrature Amplitude Modulation (QAM) comprising 2×N constellation levels, wherein said first nominal ratio equals
i
N
,
wherein i is an integer greater than 0 and smaller than N, and wherein further said preset value is equal to or less than 5%.

### Claim 20 (depends on 16)

The receiver of claim 16, wherein said first range encompasses any value below said first value, and wherein said second range encompasses any value below said second value.