# US 2019/0173586 A1 · Pam-4 transmitter precoder for 1+0.5d pr channels

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- Number: US 2019/0173586 A1
- Document ID: US20190173586A1
- Status: Published application
- Kind: A1
- Application number: 16/272,497
- Filed: 2019-02-11
- Published: 2019-06-06
- Earliest claimed: 2017-11-30
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Alessandro Cevrero; Pier Andrea Francese; Marcel A. Kossel; Christian I. Menolfi; Ilter Özkaya; Thomas H. Toifl
- Web page: https://patentgrep.com/patent/US20190173586A1

## CPC

- H04B 10/5055: {using a pre-coder}
- H03F 1/06: to raise the efficiency of amplifying modulated radio frequency waves; to raise the efficiency of amplifiers acting also as modulators {(modulation H03C)}
- H04B 10/50593: {to control the modulating signal amplitude including amplitude distortion}
- H04B 10/50597: {to control the phase of the modulating signal}
- H04B 10/524: Pulse modulation
- H04L 25/4921: {using quadrature encoding, e.g. carrierless amplitude-phase coding}
- H04L 25/4975: {Correlative coding using Tomlinson precoding, Harashima precoding, Trellis precoding or GPRS}
- H04B: TRANSMISSION
- H03F: AMPLIFIERS
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

## Claims

### Claim 1

A computer program product for generating a sequence of output symbols to be transmitted in an output stream, wherein the computer readable application, when executed on a computing device, causes the computing device to execute a method, the method comprising:
receiving a sequence of pulse amplitude modulation (PAM) scheme having an order M, (PAM-M) symbols Xn;
recoding received PAM-M symbols, wherein recoding a current received symbol Xn is performed based on immediately preceding recoded symbol Yn−1; resulting in output recoded symbols Yn of the respective received symbols Xn;
for each output recoded symbol Yn;
determining a shift value for the symbol Yn using a output recoded symbol Yn−1 immediately preceding the current symbol Yn;
determining a feed-forward equalizer (FFE) transfer function value for the symbol Yn and infinite impulse response (IIR) transfer function value for the shift value of the symbol Yn and applying the determined FFE transfer function value, the IIR transfer function value and the shift value to the symbol Yn, for generating an output symbol.

### Claim 2 (depends on 1)

The computer program product of claim 1, wherein the order M greater than two.

### Claim 3 (depends on 2)

The computer program product of claim 2, the order M is an even number between 4 and 8.

### Claim 4 (depends on 3)

The computer program product of claim 3, wherein in case the order M is 4 the shift value is equal to 0.5 or −0.5.

### Claim 5 (depends on 1)

The computer program product of claim 1 wherein the transmit filter response for a given pair of symbol amplitude levels of a current symbol and its immediately preceding symbol comprises the shift value of the current symbol in combination with an IIR response filter and a FFE filter response for the bits of the current symbol.

### Claim 6 (depends on 5)

The computer program product of claim 5 wherein the IIR filter has a filter feedback response G(z) given by the following equation 1/(1+0.5z−1).

### Claim 7 (depends on 5)

The computer program product of claim 5 wherein the IIR comprises 4 to 6 tap filters.