METHOD AND DEVICE FOR A REFERENCE TABLE-BASED CODING MECHANISM FOR COMMUNICATION SYSTEMS

Abstract

Method for encoding a signal to be transmitted via a communication channel, comprising: Receiving a signal to be transmitted; Converting the signal into a converted analog signal using a digital-to-analog converter; Receiving channel status information for a channel; Calibrating a lookup table based on channel state information; Using the calibrated lookup table to generate a coded analog signal based on the converted signal; and Transmitting the encoded analog signal, whereby the encoded signal compensates for channel distortions.

Description

TECHNICAL AREA

[0001] Embodiments of the present invention generally relate to a method and a device for a lookup table-based coding mechanism for communication systems. BACKGROUND

[0002] The present invention relates to a method and an apparatus for a lookup table-based coding mechanism for communication systems. Communication systems generally consist of a transmitter, a receiver, and a channel. The transmitter generates a signal that transmits information, which, after transmission via a channel, is received and restored by the receiver.

[0003] The information in the form of symbols embedded in the signal is generally determined by the sender, and the symbol frequency, phase, and timing can be recovered by the receiver. In the real world, transmission channels are not ideal and introduce various undesirable effects that cause signal distortion. Therefore, to recover the information transmitted in the signal, the symbol frequency, phase, and timing of the received signal must be accurately reproduced so that the received signal is synchronized with the transmitted signal and the probability of symbol errors during recognition is reduced. Precoding, such as dirty paper coding or Costa precoding, can be used at the sender in certain conventional systems to improve the recoverability of the received signal.US 2020 / 0351868 A1 refers to a system and procedure for reporting beam information and channel condition information. SUMMARY

[0004] The invention is defined by the claims. To illustrate the invention, aspects and embodiments that may or may not fall within the scope of the claims are described here. Exemplary embodiments of the present invention generally relate to a method and a device for a circuit-based coding mechanism for communication systems with a lookup table. The details of some embodiments of the subject matter described in this description are set forth in the accompanying drawings and the following description. Further features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

[0005] In one embodiment, a method for encoding a signal to be transmitted over a communication channel is provided. The method includes receiving the signal to be transmitted. The method also includes converting the signal into a converted analog signal using a digital-to-analog converter. Furthermore, the method includes receiving channel state information for a channel. The method also includes calibrating the lookup table based on the channel state information. The method also includes using the calibrated lookup table to generate an encoded analog signal based on the converted signal. The method further includes transmitting the encoded analog signal, wherein the encoded signal compensates for channel distortions.

[0006] In another embodiment, a device in a transmitter comprises at least one processor and at least one memory containing computer program code. The at least one memory and the computer program code are configured to: receive a signal to be transmitted, convert the signal into a converted analog signal using a digital-to-analog converter, receive channel state information for a channel, calibrate the lookup table based on the channel state information, use the calibrated lookup table to generate an encoded analog signal based on the converted signal, and transmit the encoded analog signal, the encoded signal compensating for the channel distortion of the channel.

[0007] In some cases, the signal to be transmitted is a Pulse Amplitude Modulation-4 (PAM-4) signal. In some embodiments, the converted analog signal comprises three eyes, and the encoded analog signal comprises three eyes. In some embodiments, the encoded analog signal is Gray-coded using the lookup table. In some embodiments, the encoded analog signal is Costa-precoded using the lookup table. In some embodiments, the encoded analog signal is Tomlinson-Harashima-coded using the lookup table.

[0008] In some embodiments, the use of the lookup table to generate an encoded analog signal based on the converted signal includes sending a handshake signal to a receiver, receiving a handshake response signal from the receiver indicating that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a receiver-side lookup table embedded in a receiver-side chipset with a central processing unit (CPU), and configuring the calibrated lookup table to perform Tomlinson-Harashima encoding. In some embodiments, the receiver-side lookup table is adjustable.

[0009] In some embodiments, the use of the lookup table to generate a coded analog signal based on the converted signal includes sending a handshake signal to a receiver, receiving a handshake response signal from the receiver indicating that the receiver is configured to decode a Tomlinson-Harashima-coded received signal using a field-programmable gate array (FPGA), and configuring the calibrated lookup table to perform Tomlinson-Harashima coding.

[0010] In some embodiments, the lookup table is also configured to include equalization.

[0011] The above summary serves only to encapsulate some exemplary embodiments in order to provide a basic understanding of some aspects of the present invention. Accordingly, it is understood that the embodiments described above are merely examples and should not be construed as limiting the scope of the present invention in any way. It is clear that the scope of the present invention includes many possible embodiments in addition to those summarized here, some of which are described further below. Any feature of one aspect or embodiment can be applied to other aspects or embodiments in any suitable combination. In particular, any feature of one method aspect or embodiment can be applied to one apparatus aspect or embodiment, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Following this general description of the revelation, reference is now made to the accompanying drawings, which are not necessarily to scale and in which the revelation is depicted as follows: Fig. Figure 1 shows a block diagram of an exemplary communication system that uses a decision-feedback equalizer (DFE) at a receiver, and an exemplary communication system that uses a Tomlison-Harashima precoding (THP); Fig. Figure 2 shows an example reference table with two input symbols according to embodiments of the present invention; Fig. Figure 3 is a flowchart showing an example method for encoding a signal to be transmitted over a communication channel according to embodiments of the present invention; Fig. 4 is a flowchart showing an example of a procedure for performing a so-called handshake with the recipient; Fig. Figure 5 shows an example of a computer system that can be embedded in the communication system; Fig. Figure 6 shows an example graphic relating to one or more embodiments disclosed herein; and Fig. Figure 7 shows an example of an eye diagram relating to one or more of the embodiments disclosed herein. DETAILED DESCRIPTION

[0013] Exemplary embodiments are described in more detail below with reference to the accompanying drawings, which illustrate some, but not all, embodiments. The embodiments can, in fact, take many different forms and should not be understood as limited to those presented here; rather, these embodiments are provided so that this disclosure meets applicable legal requirements. The same reference numbers refer to the same elements throughout. The terms "exemplary" and "example" used herein are not intended to make a qualitative assessment but merely to illustrate an example. Therefore, the use of such terms should not be understood as limiting the scope of the embodiments of the present invention.

[0014] Embodiments of the present disclosure are described below with reference to block diagrams and flowchart figures. It should therefore be understood that each block of the block diagrams and flowchart figures can be implemented in the form of a computer program product, a complete hardware implementation, a combination of hardware and computer program products and / or devices, systems, computing devices / units, computing units, and / or the like, which execute instructions, operations, steps, and similar interchangeable terms (e.g., the executable instructions, instructions for execution, program code, and / or the like) on a computer-readable storage medium. For example, the fetching, loading, and execution of code can be sequential, such that one instruction is fetched, loaded, and executed at a time.In some exemplary embodiments, fetching, loading, and / or execution can occur in parallel, allowing multiple instructions to be fetched, loaded, and / or executed simultaneously. Thus, such embodiments can produce specifically configured machines that perform the steps or operations specified in the block diagrams and flowcharts. Accordingly, the block diagrams and flowchart figures support various combinations of embodiments for performing the specified instructions, operations, or steps.

[0015] In the field of high-performance computing (HPC) and data center (DC) communications, the demand for high capacity, low latency, low power consumption, and compact connectivity is constantly increasing. Various applications, such as HPC clustering, deep learning, cloud computing and storage, and mobile systems, all benefit from high capacity, low latency, low power consumption, and compact connectivity. Once information is digitized, it will most likely be processed or stored by an HPC or DC infrastructure at some point.

[0016] In the HPC field, communication standards for computer networks, such as InfiniBand, are characterized by very high throughput and very low latency at the physical layer. As HPC systems require ever-increasing capacity, data center environments have benefited from these developments and adopted the new technologies, adapting them to their own specific requirements (e.g., lower costs and reduced power consumption). These requirements are traditionally met by relaxing the specifications, for example, regarding the bit error rate (BER), and by tolerating slightly less capacity.

[0017] However, relaxing these requirements may not be beneficial depending on the applications and operations being performed. To meet the connectivity needs of DC and HPC clusters, connections have undergone rapid development from 14G to 28G, 50G, and finally 100G per single lane. This incremental growth has led to some bottlenecks when using traditional non-return-to-zero (NRZ) modulation mechanisms. Therefore, pulse-amplitude modulation (PAM)-4 is being introduced. PAM-4 offers approximately twice the capacity of non-return-to-zero (NRZ) at the same bandwidth. There are some challenges that, if properly addressed, could pave the way for further scaling of PAM-4 systems in the future.

[0018] A common way to convert bit pairs into a PAM-4 mapping is a direct mapping of input={00,01,10,11} to output={-3,-1,1,3} when mapped to analog values. To reduce errors in case of faulty recovery, Gray encoding can be applied, ensuring that only one bit changes between adjacent symbols. This results in a conversion of input={00,01,10,11}, which, when Gray-encoded, becomes input={00,01,11,10}, and, when converted to analog values, output={-3,-1,1,3}. Converting two bits into a single value in a PAM-4 signal allows for higher spectral efficiency. This increased spectral efficiency in modulation formats enables a reduction in the bandwidth requirements of all components in the end-to-end interconnect channel.

[0019] An end-to-end link can consist of various components with limited frequency responses: laser sources, photodiodes, transimpedance amplifiers, amplifiers, modulator drivers, bond wire connections, and optical fibers. To ensure acceptable signal integrity in an end-to-end link, the systems must ensure that signal distortions caused by the channel are properly compensated, for example, by equalization at the receiver or transmitter, or by pre-coding at the transmitter.

[0020] Equalization can be performed using feed-forward equalizers (FFEs). FFE equalizers are implemented using finite impulse response (FIR) digital filters: FIR filters have pre-cursor and post-cursor taps, each with a different weighting corresponding to the inverse of the impulse response of the end-to-end link, thus effectively equalizing the signals transmitted over such a link. FFE equalizers can be placed at the transmitter, the receiver, or both simultaneously. Alternatively, decision feedback equalizers (DFEs) can be placed at the receiver to compensate for post-cursor interference. A DFE takes a sample of the currently recovered bit, applies the inverse of the channel transfer function, estimates the magnitude of the post-cursor interference, and subtracts this amount from the incoming signal, thus enabling correct recovery of the next bit.

[0021] DFE offers many advantages, such as no noise amplification, performance close to the Shannon capacitance of the underlying channel, and compatibility with adaptive algorithms for determining the channel's transfer function. However, DFE introduces negative error propagation effects at low signal-to-noise ratios (SNR) and requires all computational operations to be performed within less than 1 UI, which burdens the electronic design and implementation at increasing line rates. Therefore, at high bit rates and high line rate requirements, such as line rates exceeding 50 gigabits per second, DFE may not be a practical option due to limitations in electronic design.

[0022] Precoding mechanisms such as dirty paper coding (DPC), Costa precoding, Tomlison-Harashima precoding (THP), or similar methods provide a way to implement DFE functionality at the transmitter rather than the receiver. THP, for example, consists of a decision system in the transmitter that generates a sequence based on the value of the current and the preceding bit. The preceding bit is used to equalize the current bit by applying the inverse of the impulse response channel (post-cursor compensation). The equalized signal is then passed through a modulo unit connected to a modulo signal processing operation.

[0023] Fig. Figure 1 shows a block diagram of an example communication system using a DFE at receiver 100A and an example communication system 100B using THP equalization. As shown in Fig. As shown in Figure 1, in system 100A, transmitter 102A sends a signal via channel 104A to receiver 106A. Receiver 106A implements a DFE receiver that compensates for the distortions caused by the channel. In system 100B, transmitter 102B implements precoding that compensates for the distortions caused by the channel and then transmits the precoded signal via channel 104B to receiver 106B.

[0024] Fig. Figure 2 shows an example lookup table with two input symbols. The two input symbols, the main symbol N and a precursor symbol, each consist of a least significant bit and a most significant bit, and an output of M bits. A lookup table can have more than two input symbols with a varying number of precursor and postcursor symbols. The M bits can be used as input for a digital-to-analog converter.

[0025] Fig. Figure 3 is a flowchart illustrating an example of a method for encoding a signal to be transmitted over a communication channel according to the embodiments of the present invention. It is understood that each block of the flowcharts and combinations of blocks within the flowcharts can be implemented by various means. In some embodiments, certain operations described herein may be modified or extended as described below. Furthermore, some embodiments may also include additional optional operations. It should be noted that each of the modifications, optional additions, or extensions described herein may be included with the operations described herein either alone or in combination with other features described herein. Fig. The three operations shown can be performed, for example, by a sample computer system 500 (shown in Fig. 5) is carried out, which is embedded in a communication system, such as a transmitter in a communication system.

[0026] In some embodiments, the computing system 500 is configured at operation 302 to receive a signal to be transmitted. In some embodiments, the computing system 500 is a firmware computing system embedded in a transmitter of a communication system. In some embodiments, the signal to be transmitted can be received by another device configured to transmit information about a signal using the communication system. In some embodiments, the signal to be transmitted can be a digital signal comprising one or more bits. In some cases, the signal to be transmitted is a pulse-amplitude modulation (PAM-4) signal.

[0027] In some embodiments, the computer system 500 is configured to convert the signal to be transmitted into a converted analog signal by using an embedded digital-to-analog converter. In some embodiments, the digital-to-analog converter may be communicatively coupled to the computer system 500 or otherwise made available to it. In some cases, the computer system 500 may be a firmware computer system that is communicatively coupled to one or more circuit modules in the communication system and configured to control them.

[0028] In some embodiments, during operation 306, the computer system 500 is configured to receive channel state information for a channel. The channel may, for example, be a channel over which the signal to be transmitted is expected to be transmitted. In some embodiments, operation 306 occurs before operations 302 and 304, so that the computer system can receive channel state information before it receives a signal to be transmitted. In some embodiments, the computer system 500 is configured to determine the channel state information based on one or more filters associated with the channel. For example, in some embodiments, the computer system 500 is configured to determine the channel state information based on an impulse response of one or more filters associated with the channel.In some embodiments, the computing system 500 is configured to determine the channel state information based on a statistical characterization of the channel. In some embodiments, the computing system 500 is configured to determine the channel state information based on a handshake signal transmitted between the sender and the receiver. In some embodiments, the channel state information can be stored in the memory 520.

[0029] In some embodiments, the channel state information includes information indicating an expected distortion that the channel may cause, such as channel distortion estimation information. This channel distortion estimation information may relate to linear and / or nonlinear phenomena associated with the channel. Additionally or alternatively, in some embodiments, the channel state information includes statistics associated with symbols connected to the channel. For example, in some embodiments, the channel state information additionally or alternatively includes intersymbol interference information associated with the channel. Additionally or alternatively, in some embodiments, the channel state information includes channel response information associated with the channel.Additionally or alternatively, in some embodiments, the channel state information can be generated based on a channel transfer function associated with the channel (e.g., an end-to-end channel transfer function). For example, in some embodiments, the handshake signal can be influenced by the channel transfer function as it traverses the channel, thereby generating the channel state information. In some embodiments, the handshake signal can contain various analog levels configured in a predefined manner. Furthermore, the handshake signal can contain a series of transitions. In one aspect, the handshake signal can apply a specific transfer function to analog segments of the handshake signal to facilitate the generation of the channel state information.

[0030] In some embodiments, during Operation 308, the computer system 500 is configured to calibrate a lookup table based on the channel status information. The lookup table can be configured to map one or more input values ​​to an output value. In some embodiments, the lookup table is a hardware-based lookup circuit embedded in the communication system and controlled by the computer system 500. For example, the hardware-based lookup circuit may include one or more hardware gates, one or more hardware latches, one or more hardware relays, and / or one or more other hardware components. In some embodiments, Operation 308 occurs prior to Operations 302 and 304, allowing the computer system to calibrate the lookup table before receiving a signal to be transmitted.In some embodiments, the lookup table can be embedded in a clock data recovery unit based on the lookup table. In one embodiment, one or more lookup table transitions can be matched based on channel state information. A lookup table transition can include an initial state and an end state. Furthermore, in certain embodiments, hardware components of the lookup table can be associated with corresponding transitions. In certain embodiments, for example, a lookup table transition can include one or more connections and / or one or more hardware components. In another embodiment, the weighting of one or more hardware components of the lookup table can be matched based on channel state information.For example, the weighting of one or more hardware components in the lookup table can be repeatedly adjusted based on the channel state information until a signal to be transmitted meets a defined quality criterion.

[0031] In some embodiments, during operation 310, the computing system 500 can use the calibrated lookup table to generate a coded analog signal based on the converted analog signal, at least using the converted analog signal as input to the lookup table. The lookup table can, in some cases, be used to implement various encodings, such as Costa precoding, Tomlinson-Harashima precoding, Gray coding, or similar. In some embodiments, the coded analog signal has one or more symbol durations, an amplitude, or other signal parameters that are adjusted based on the lookup table. In some embodiments, the calibrated lookup table can also be configured to account for signal equalization (e.g., by adjusting the lookup table values ​​to accommodate the equalization).In some embodiments relating to equalization, for example, an input value of the calibrated lookup table can be weighted to correspond to a desired output value that includes an equalization factor. In another embodiment relating to encoding, an input value of the calibrated lookup table can be weighted based on a digital value associated with the encoding.

[0032] For example, in certain embodiments, an input value of the calibrated lookup table can be weighted based on a digital value associated with the Costa pre-coding, a digital value associated with the Tomlinson-Harashima pre-coding, or a digital value associated with the Gray coding. In some embodiments, the calibrated lookup table can be configured to perform only the coding, and a second, similarly calibrated lookup table can be used to perform the equalization.

[0033] In some embodiments, during operation 312, the computer system 500 sends the coded analog signal to a receiver via the channel for which the computer system has previously obtained channel information.

[0034] In some embodiments, the transmitter in which the computer system 500 is embedded can communicate with a receiver in which another computer system may be embedded, in order to perform a handshake before the transmission of the signal or before the generation of the coded analog signal. In one embodiment, the handshake can be associated with a recognition process in conjunction with a communication protocol. Fig. 4 is a flowchart showing an example procedure for performing a handshake with the receiver. As in Fig. As shown in Figure 4, during Operation 402, the computer system 500 can transmit a handshake signal to a receiver. The handshake signal can be a signal for exchanging information about whether the receiver has an embedded firmware computer system and whether the receiver is capable of decoding one or more of the coding mechanisms used by the computer system 500. In some embodiments, the handshake signal can be transmitted during the establishment of a communication link. In one embodiment, the establishment of the communication link can also be associated with the recognition process related to the communication protocol.

[0035] In Operation 404, the sender can receive a handshake response signal from the receiver. The handshake response signal can indicate whether the receiver is able to decode one or more Gray-coded signals, a Costa-precoded signal, or a Tomlinson-Harashima-coded signal.

[0036] In Operation 406, the sender can configure the lookup table according to the received handshake response signal. For example, if the handshake response signal indicates that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a receiver-side lookup table embedded in a receiver-side chipset with a central processing unit (CPU), the sender can configure the calibrated lookup table to perform Tomlinson-Harashima encoding.For example, if the handshake response signal indicates that the receiver is configured to decode a Costa-precoded received signal using a receiver-side lookup table embedded in a receiver-side chipset with a central processing unit (CPU), the sender can configure the calibrated lookup table to perform Costa precoding. Conversely, if the handshake response signal indicates that the receiver is not configured to decode a precoded signal, the sender can configure the lookup table to perform only equalization.

[0037] In one embodiment relating to a transmitter, the transmitter's lookup table can receive a sequence of digital data (e.g., a sequence of ones and zeros) as input. Based on an encoding method and / or equalization process, the transmitter's lookup table can generate a coded analog signal. In certain embodiments, a computing system (e.g., Computing System 500) can determine one or more weights for one or more hardware components of the transmitter's lookup table. In one aspect, the one or more weights can be determined based on the encoding and / or equalization. Furthermore, the transmitter can transmit the coded analog signal to a receiver.

[0038] In another embodiment, relating to a receiver, the receiver's lookup table can receive an encoded analog signal as input. The encoded analog signal can be provided by a transmitter. Based on some type of encoding and / or equalization process, the receiver's lookup table can generate a sequence of digital data (e.g., a sequence of ones and zeros). In certain embodiments, a computing system (e.g., the Computing System 500) can determine one or more weights for one or more hardware components of the receiver's lookup table. In one aspect, the one or more weights can be determined based on the encoding and / or equalization. In one example, the receiver's lookup table can exchange one or more bits of a sequence of digital data to demodulate an encoding (e.g., Gray coding) performed at the transmitter.

[0039] In some embodiments, the handshake signal can be influenced by an end-to-end channel transfer function as it traverses a channel, generating channel state information that can be used to generate one or more lookup table weights. For example, on a receive side of the handshake path, the channel state information can be extracted to aid in the generation of one or more equalization weights for the lookup table.

[0040] In some embodiments, the handshake signal can contain various analog levels configured in a predefined manner. The handshake signal can also contain a series of transitions. In one aspect, the handshake signal (e.g., as it traverses a channel) can undergo end-to-end channel processing, imposing a specific transfer function on analog segments of the handshake signal. In some embodiments, this imprinting can facilitate the generation of channel state information. Additionally, in some embodiments, an inverse transfer function can be used to determine one or more weights for the lookup table.

[0041] Fig. Figure 5 shows an example of a Computer System 500, which can be embedded in the communication system. The Computer System 500 can be a firmware computer system with one or more circuit modules, such as the one shown in Figure 5. Fig. The lookup table circuit shown in Figure 2 is communicatively connected. The computer system 500 may include or otherwise be connected to a processor 510, a memory circuit 520, and a communication circuit 530. In some embodiments, the processor 510 (which may include multiple processors or co-processors, or other processing circuits connected to the processor) may be connected to the memory circuit 520. The memory circuit 520 may include a non-transient memory circuit and may include one or more volatile and / or non-volatile memories. In some examples, the memory circuit 520 may be an electronic storage device (e.g., a computer-readable storage medium) configured to store data that can be retrieved by the processor 510.In some examples, the data stored in memory 520 may contain one or more sets of lookup table values, data for generating lookup table values ​​based on channel state information and a desired coding mechanism, or the like, to enable the device to perform various functions or procedures according to the embodiments of the present invention described herein.

[0042] In some examples, the 510 processor can be implemented in various ways. For instance, the processor can be implemented as one or more different hardware processing units, such as a microprocessor, a coprocessor, a digital signal processor (DSP), a controller, or a processing element with or without an associated DSP. The 510 processor can also be contained within various other processing circuits, including integrated circuits such as an FPGA (field-programmable gate array), a microcontroller unit (MCU), an ASIC (application-specific integrated circuit), a hardware accelerator, or a special-purpose electronic chip. Furthermore, in some embodiments, the processor can contain one or more processing cores that can operate independently. A multi-core processor can enable multiprocessing within a single package.Additionally or alternatively, the processor may include one or more processors configured in tandem over the bus to enable independent instruction execution, pipelining, and / or multithreading. In some embodiments, the 510 processor is a microprocessor.

[0043] In one embodiment, the processor 510 can be configured to execute instructions, such as computer program code or instructions stored in the memory circuit 520 or otherwise accessible to the processor 510. Alternatively or additionally, the processor 510 can be configured to execute hard-coded functions. Regardless of whether it is configured by hardware or software instructions, or by a combination thereof, the processor 510 can represent an arithmetic unit (e.g., physically embodied in a circuit) configured to perform operations according to an embodiment of the present invention described herein. For example, if the processor 510 is implemented as an ASIC, FPGA, or the like, the processor can be configured as hardware to perform the operations of an embodiment of the invention.Alternatively, if the Processor 510 is embodied to execute software or computer program instructions, the instructions can specifically configure the Processor 510 to perform the algorithms and / or operations described herein when the instructions are executed. In some cases, the processor can... However, 510 may be a processor of a device (e.g., a mobile device or a stationary computer) that is specifically configured for use in an embodiment of the present invention by further configuring the processor using instructions to perform the algorithms and / or operations described herein. The processor 510 may also include a clock, an arithmetic logic unit (ALU), and logic gates, which are configured, among other things, to support the operation of the processor 510.

[0044] The Computer System 500 can optionally include the Communication Circuit 530. The Communication Circuit can be any means, either hardware-based or a combination of hardware and software, configured to receive and / or transmit data to / from a network and / or other device or module that communicates with the Computer System 500. In this respect, the Communication Interface can include, for example, supporting hardware and / or software to enable communication. Thus, the Communication Circuit 530 can include, for example, a communication modem and / or other hardware / software to support communication over wired connections, a Universal Serial Bus (USB), an integrated receiver circuit, or other mechanisms.

[0045] Fig. Figure 6 shows an example diagram 600 relating to one or more embodiments disclosed herein. Diagram 600 shows the bit error rate (BER) versus the signal-to-noise ratio (SNR) for a signal provided by a lookup table disclosed herein. In one embodiment, diagram 600 may relate to two transmitter models (e.g., VCSEL (vertical-cavity surface-emitting laser) models), each with DC current values ​​of 7 mA, 8 mA, and 9 mA, and peak-to-peak voltage values ​​of 0.5 and 0.8. In one example, the two transmitter models may be connected using an electrical back-to-back test (EBTB) and an optical back-to-back test (OBTB). As shown in diagram 600, a BER curve 602 refers to a theoretical limit, a BER curve 604 to OBTB with a first type of equalization (e.g. DFE), a BER curve 606 to OBTB with a second type of equalization (e.g., THP), a BER curve 608 refers to EBTB without equalization, a BER curve 610 refers to OBTB with a third type of equalization (e.g. LPE), and a BER curve 612 refers to OBTB without equalization.

[0046] Fig. Figure 7 shows an example of an eye diagram 700 relating to one or more of the embodiments disclosed herein. The eye diagram 700 may, for example, be an eye diagram for a signal associated with a lookup table disclosed herein.

[0047] Many modifications and other embodiments of the present inventions set forth herein will occur to a person skilled in the art in the field to which these inventions belong when considering the teachings set forth in the preceding descriptions and the accompanying drawings. It is therefore self-evident that the present inventions are not limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.Although the foregoing descriptions and the accompanying drawings describe exemplary embodiments in connection with certain example combinations of elements and / or functions, it should be noted that other combinations of elements and / or functions can be provided by alternative embodiments without departing from the scope of the appended claims. In this respect, for example, other combinations of elements and / or functions than those expressly described above are conceivable, as may be set forth in some of the appended claims. Although specific terms are used here, they are used only in a general and descriptive sense and not for the purpose of limitation.

[0048] It is understood that the aspects and embodiments described above are only exemplary and that changes may be made to the details within the scope of the claims.

[0049] Each device, method and feature disclosed in the description and (where applicable) in the claims and drawings can be provided independently or in any suitable combination.

[0050] The reference numerals included in the claims are for illustrative purposes only and do not restrict the scope of the claims.

Claims

[1] Method for encoding a signal to be transmitted over a communication channel, comprising: Receiving a signal to be transmitted; Converting the signal into a converted analog signal using a digital-to-analog converter; Receiving channel status information for a channel; Calibrating a lookup table based on channel state information; Using the calibrated lookup table to generate a coded analog signal based on the converted signal; and Transmitting the encoded analog signal, whereby the encoded signal compensates for channel distortions. [2] Method according to claim 1, wherein the signal to be transmitted is a Pulse Amplitude Modulation (PAM-4) signal. [3] Method according to claim 2, wherein the converted analog signal comprises three eyes and wherein the encoded analog signal comprises three eyes. [4] Method according to any of the preceding claims, wherein the coded analog signal is Gray-coded using the lookup table. [5] Method according to any one of claims 1 to 3, wherein the coded analog signal is pre-coded using the Costa lookup table. [6] Method according to any one of claims 1 to 3, wherein the encoded analog signal is encoded using the Tomlinson-Harashima lookup table. [7] Method according to claim 6, wherein the lookup table is used to generate a coded analog signal based on the converted signal, comprising: Transmitting a handshake signal to a receiver; Receiving a handshake response signal from the receiver indicating that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a receiver-side lookup table embedded in a receiver-side chipset with a central processing unit (CPU); and Configure the calibrated lookup table to perform a Tomlinson-Harashima coding. [8] Method according to claim 7, wherein the receiver-side lookup table is adjustable. [9] Method according to claim 6, wherein the use of the lookup table to generate a coded analog signal based on the converted signal comprises: Transmitting a handshake signal to a receiver; Receiving a handshake response signal from the receiver, indicating that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a field-programmable gate array (FPGA); and Configure the calibrated lookup table to perform a Tomlinson-Harashima coding. [10] Method according to any of the preceding claims, wherein the lookup table is further configured to include an equalization. [11] Device in a transmitter comprising at least one processor and at least one memory containing a computer program code, wherein the at least one memory and the computer program code are configured to communicate with the at least one processor: to receive a signal to be transmitted; to convert the signal into an analog signal using a digital-to-analog converter; To receive channel status information for a channel; to calibrate a lookup table based on the channel status information; to use the calibrated lookup table to generate a coded analog signal based on the converted signal; and to transmit the encoded analog signal, whereby the encoded signal compensates for channel distortions of the channel. [12] Device according to claim 11, wherein the signal to be transmitted is a Pulse Amplitude Modulation-4 (PAM-4) signal. [13] Device according to claim 12, wherein the converted analog signal comprises three eyes and wherein the encoded analog signal comprises three eyes. [14] Device according to claim 11, 12 or 13, wherein the coded analog signal is Gray-coded using the lookup table. [15] Device according to claim 11, 12 or 13, wherein the coded analog signal is pre-coded using the Costa lookup table. [16] Device according to claim 11, 12 or 13, wherein the coded analog signal is coded using the Tomlinson-Harashima lookup table. [17] Device according to claim 16, wherein the at least one memory and the computer program code are further configured to: to send a handshake signal to a receiver; to receive a handshake response signal from the receiver indicating that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a receiver-side lookup table embedded in a receiver-side chipset with a central processing unit (CPU); and to configure the calibrated lookup table for performing a Tomlinson-Harashima coding. [18] Device according to claim 17, wherein the receiver-side lookup table is adjustable. [19] Device according to claim 16, wherein the at least one memory and the computer program code are further configured to: to send a handshake signal to a receiver; to receive a handshake response signal from the receiver indicating that the receiver is configured to decode a Tomlinson-Harashima-encoded received signal using a field-programmable gate array (FPGA); and to configure the calibrated lookup table for performing a Tomlinson-Harashima coding. [20] Device according to any one of claims 11 to 19, wherein the lookup table is further configured to include equalization.

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