Power-based signal modulation for consistent performance and noise resistance

Abstract

This invention introduces a modulation and demodulation method that ensures uniformly spaced power levels by adopting non-uniformly spaced voltage levels, leading to improved noise immunity and energy efficiency. By maintaining a constant power difference between adjacent signal levels, the system ensures uniform noise performance and enhanced coding efficiency. This approach is applicable to M-PAM and M-QAM systems, optimizing power distribution across sub-carriers in multi-carrier communication systems like OFDM. The method enables efficient power utilization, reducing energy consumption while enhancing signal robustness. It supports integration with advanced encoding schemes such as block, convolutional, turbo, and LDPC encoders. Designed for wireless communication systems, base stations, and energy-efficient IoT networks, this invention provides a scalable and practical solution for next-generation high-speed, low-power data transmission, ensuring optimal performance across different communication environments.

Description

[0001] Power-Based Signal Modulation for Consistent Performance and Noise Resistance

[0002] Field of the Invention

[0003] The present invention relates to signal modulation systems, and more particularly to a method and system for modulation and demodulation using non-uniformly spaced voltage levels to achieve uniformly spaced power levels between adjacent signals.

[0004] Background of the Invention

[0005] In modem communication systems, modulation plays a crucial role in encoding information onto carrier signals for efficient transmission. Pulse Amplitude Modulation (PAM) is a widely used modulation technigue in both wired and wireless communication, where information is conveyed by varying the amplitude of pulse-shaped signals. Conventionally, PAM systems follow Hartley’s approach, which employs uniformly spaced voltage levels for simplicity. However, this approach results in fundamental inefficiencies due to the non-uniform power differences between adjacent levels, leading to non-uniform noise immunity and suboptimal power utilization.

[0006] Traditional PAM systems with evenly spaced voltage levels (e.g., 1 V, 2V, 3V) exhibit power levels that follow a guadratic relationship (e.g., 1W, 4W, 9W). The increasing power gap 3W between 1V and 2V, and 5W between 2V and 3V creates inconsistencies in noise immunity across modulation levels, degrading coding performance and signal reliability.Despite these inefficiencies, widely used communication technologies such as Orthogonal Frequency Division Multiplexing (OFDM) and Multi-Level Quadrature Amplitude Modulation (M-QAM) continue to rely on Hartley’s voltage-based modulation while leveraging Shannon’s encoding theorem. However, this hybrid approach does not fully optimize power efficiency or noise performance.

[0007] Energy efficiency is a growing concern in modem networks, particularly in mobile communications, base stations, and loT devices. Optimizing power distribution at the modulation level can significantly reduce transmission power consumption, enhance overall system efficiency, and improve network sustainability. Transitioning from voltagebased to power-based modulation enables consistent noise immunity, greater transmission reliability, and improved energy efficiency in M-PAM and multi-carrier modulation systems.

[0008] In digital communication, Quadrature Amplitude Modulation (QAM) is a widely used technique that combines amplitude and phase modulation to achieve higher data rates. Conventional QAM systems use uniformly spaced voltage levels to represent different symbols in the signal constellation. However, uniform voltage spacing results in non-uniform power spacing, impacting system performance. The uneven power distribution leads to varying noise immunity across modulation levels, reducing system efficiency and signal reliability.Another critical consideration in QAM design is the peak-to-average power ratio (PAPR). High PAPR can cause signal distortion and reduce the efficiency of power amplifiers. Techniques that maintain spectral efficiency while reducing PAPR are an active area of research. Additionally, as higher modulation orders are adopted to support increased data rates, modulator and demodulator complexity increases, affecting power consumption, chip area, and cost. Therefore, methods to simplify implementation while ensuring optimal performance are desirable.

[0009] Furthermore, modulation schemes must be robust against channel impairments such as noise, fading, and interference. Optimizing constellation designs to improve noise immunity and minimize error rates under realistic channel conditions remains a significant challenge.

[0010] As communication systems continue to evolve, there is a persistent demand for improved modulation techniques that enhance performance, efficiency, and reliability. Addressing the inefficiencies of conventional voltage-based modulation and transitioning to power-based modulation presents a significant opportunity to optimize energy utilization and improve the overall performance of modern communication networks.

[0011] Objective of the Invention

[0012] The principal objective of the present invention is to provide a method and system for modulation and demodulation that utilizes non-uniformly spaced voltage levels to achieve uniformly spaced power levels betweenadjacent signals, ensuring consistent noise immunity across all modulation levels.

[0013] Another objective of the present invention is to introduce an adaptive power-based modulation scheme that dynamically adjusts power levels in response to real-time channel conditions, improving signal reliability and communication robustness.

[0014] Another objective of the present invention is to enhance the efficiency of high-order modulation schemes such as Multi-Level Quadrature Amplitude Modulation (M-QAM) and Pulse Amplitude Modulation (M-PAM) by minimizing power wastage while maintaining superior data rates and signal quality.

[0015] Another objective of the present invention is to simplify receiver-side demodulation by optimizing decision boundaries in power-based modulation, reducing computational complexity while improving bit error rate (BER) performance.

[0016] Another objective of the present invention is to reduce the peak-to-average power ratio (PAPR) in power-based modulation, enabling more efficient power amplifier operation, lower signal distortion, and extended battery life in wireless communication devices.

[0017] A further objective of the present invention is to ensure seamless compatibility of the proposed power-based modulation scheme with existing wired and wireless communication infrastructure, including OFDM and MIMO systems, without requiring significant hardware modifications.Summary of the Invention

[0018] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0019] An aspect of the present invention introduces an energy-efficient modulation and demodulation method that employs non-uniformly spaced voltage levels to achieve uniformly spaced power levels across adjacent signal levels. This novel approach ensures uniform noise immunity, enhances power efficiency, and improves signal reliability in various communication systems, particularly in Pulse Amplitude Modulation (PAM), Orthogonal Frequency Division Multiplexing (OFDM), and Multi-Level Quadrature Amplitude Modulation (M-QAM) networks.

[0020] Traditional modulation schemes rely on Hartley’s approach, which uses uniformly spaced voltage levels, resulting in non-uniform power differences between adjacent levels. This leads to inconsistent noise performance and inefficient power utilization. By reinterpreting Shannon’s capacity theorem, the invention ensures constant power differences across modulation levels, enhancing error resilience, coding performance, and spectral efficiency.

[0021] The proposed system integrates an adaptive modulation framework, allowing seamless compatibility with existing multi-carrier communicationsystems. By shifting from voltage-based level spacing to power-based level spacing, the invention significantly reduces transmission power requirements, enhances signal decoding accuracy, and improves overall energy efficiency. These advantages make it particularly suitable for nextgeneration wireless networks, loT devices, and low-power communication systems.

[0022] Additionally, the modulation technique supports various encoding schemes such as block encoding, convolutional encoding, turbo encoding, and LDPC encoding to further improve error correction and system reliability. This innovative approach not only enhances modulation performance but also enables more sustainable and power-efficient wireless communication systems.

[0023] Brief description of the drawings

[0024] The figures described below depict various aspects of the system and methods disclosed herein. It should be understood that each figure depicts an embodiment of a particular aspect of the disclosed system and methods, and that each of the figures is intended to accord with a possible embodiment thereof. Further, wherever possible, the following description refers to the reference numerals included in the following figures, in which features depicted in multiple figures are designated with consistent reference numerals.FIG.1 depicts the Shannon communication system, incorporating non-uniform ly spaced voltage levels or uniformly spaced power levels (100), in accordance with aspects of the present invention.

[0025] FIG. 2 presents a block diagram of a Signal Transmission and Reconstruction System (200) in accordance with an embodiment of the present invention.

[0026] FIG.3 provides a flowchart detailing the modulation process (300) according to one embodiment of the present invention.

[0027] FIG.4 presents a flowchart outlining the demodulation process (400) in accordance with one embodiment of the present invention.

[0028] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.

[0029] Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

[0030] Detailed Description of the Invention

[0031] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0032] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0033] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0034] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

[0035] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skillin the art, may occur in amounts that do not preclude the effect the characteristic is intended to provide.

[0036] Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions, in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.

[0037] Figure 1 provides a detailed graphical representation of the voltage levels and the corresponding power levels in a Pulse Amplitude Modulation (PAM) system based on Shannon’s capacity formula. The figure illustrates the innovative approach of using non-uniform voltage spacing to maintain a constant power difference between adjacent levels, thereby improving noise immunity and maximizing channel capacity.

[0038] In a traditional Shannon-based modulation system, the channel capacity C for a single quadrature component is given by the formula:

[0039]

[0040] where:

[0041] • C = Channel capacity in bits per channel use

[0042] • P = Average received power per dimension (I- or Q-component) • N = Noise power per dimension (I- or Q-component)

[0043] • P / N = Signal-to-noise ratio (SNR)

[0044] The achievable number of signal levels depends on the SNR. In conventional PAM systems or Hartley systems, the signal levels are uniformly spaced in terms of voltage. This results in non-uniform power differences between adjacent levels since power is proportional to the square of voltage. The power difference between two adjacent signal levels as per Shannon’s capacity is given by:

[0045] 2N = 2cr2

[0046] where o is the standard deviation of the noise power. This power difference is also called as equivocation or information uncertainty, and this is a statistical constant defined as ‘variance.’ Consequently, the voltage difference between adjacent levels is:

[0047] V2N = V2 x o- This implies that the noise immunity is uniform across the modulation levels, as the noise margin does not vary depending on the signal level.

[0048] The invention introduces a key modification by ensuring that the power difference rather than the voltage difference between adjacent levels remains constant. Since power is proportional to the square of the voltage,this leads to non-uniform voltage spacing between adjacent levels. Specifically, the power difference between two adjacent levels is maintained at a constant value kN, where k is a design constant. The voltage levels are therefore defined by:

[0049] Vm= / ma

[0050] where:

[0051] • Vm= Voltage of the mthsignal level

[0052] • m = Signal index

[0053] • o = Base signal voltage corresponding to the noise power or standard deviation

[0054] Since the voltage levels are spaced according to the square root of the signal index, the difference between adjacent voltage levels increases as the signal index increases. This ensures that the power difference and thereby the noise immunity remains consistent across all levels.

[0055] Assuming that Vo=O, the voltage levels are defined as:

[0056]

[0057] For a symmetric PAM system where signal levels swing from negative to positive voltages, the negative levels are represented as:

[0058] V_m= — \[m • a

[0059] Thus, the complete set of constellation levels is:

[0060] Vm= / m • VIwhere Vi =o is the base signal voltage. The symmetric nature of the constellation ensures that the signal levels are balanced around the zero point, reducing DC offset and improving system performance.

[0061] The figure demonstrates two distinct modulation schemes represented by sections [A] and [B], In section [A], the modulation scheme uses non-uniform ly spaced voltage levels. The voltage levels are positioned at values of -sqrt(2)o, -o, +o, and +sqrt(2)o. This non-uniform spacing is designed to optimize power efficiency and improve signal integrity by aligning with the natural distribution of signal noise and channel conditions. By adjusting the voltage levels in a non-linear manner, the system can achieve consistent power distribution and improved noise immunity. For illustration purpose we have not included zero voltage level between the levels -o, and +o. This is within the scope.

[0062] In section [B], the modulation scheme achieves uniformly spaced power levels. The voltage levels are strategically positioned at 0, +o, +sqrt(2)o, +sqrt(3)o, and +2o. This configuration ensures that the power difference between adjacent levels remains constant, resulting in improved signal consistency and enhanced resistance to noise variations. The uniform spacing in power levels helps maintain consistent signal-to-noise ratio (SNR) across different transmission conditions, leading to enhanced overall communication performance. For illustration purpose we have not included the negative voltage levels. This is within the scope.The invention leverages the benefits of both non-uniform voltage spacing and uniform power level spacing to optimize the trade-off between power efficiency and noise resistance. The combination of these techniques ensures enhanced data transmission reliability, reduced error rates, and improved communication performance, particularly in challenging signal environments.

[0063] The proposed modulation scheme ensures that noise immunity remains uniform across all levels since the power difference between adjacent levels is constant. This differs from traditional PAM systems, where noise immunity varies depending on the signal level. The system also enables higher data rates since the channel capacity increases with the number of available levels, while maintaining consistent noise performance.

[0064] Additionally, the symmetrical nature of the signal set allows for the use of both positive and negative swings, effectively doubling the available signal levels. Shannon’s capacity formula does not account for this doubling directly, but it implies that the system can achieve the same capacity with half the power if both positive and negative swings are used. This enhances power efficiency and increases the overall robustness of the communication system.

[0065] The invention is directly applicable to PAM systems and can be extended to complex modulation schemes such as Quadrature Amplitude Modulation (QAM) and Orthogonal Frequency Division Multiplexing (OFDM). In OFDM systems, increasing the number of sub-carriers typicallyrequires additional power. However, with the proposed scheme, each increase in signal level or sub-carrier requires only one unit of power, improving the power efficiency of the entire system. This also implies that if we have more than one sub-carriers, then each sub-carrier can have different number uniform power levels, with or without zero voltage level, with or without negative voltage levels. A constellation table to illustrate this is given below for two sub-carriers with frequencies fo and 2fo:

[0066]

[0067] A demodulation rule can be envisaged that understands the sub-sets from Sr. no. 1 to Sr.no. 4 as BPSK and the remaining sub-sets as 3-PAM. It is also possible to not use the Sr. no. 9, the all zero level. The current scheme envisages and enables mix of different modulation schemes, e.g. BPSK and 3-PAM. The constellation diagram looks like given below:Constellations

[0068]

[0069] Figure 1 also illustrates specific examples that clarify the proposed modulation scheme based on constant power difference between adjacent levels. In Example [A], the invention demonstrates a two-level (two-power level) Shannon system where the zero-voltage level is not included. The signal levels swing symmetrically from negative to positive values. In this case, the four voltage levels are set at ± o and ±sqrt(2)o, where o is the standard deviation of noise. This results in four distinct signal levels with a constant power difference between them, ensuring consistent noise immunity.

[0070] In Example [B], the invention extends to a five-level Shannon system where the zero-voltage level is included as a valid modulation level. The voltage levels does not swing from negative to positive values, resulting in five distinct levels: 0, +o, +sqrt(2)o, +sqrt(3)o and +2o. The inclusion of the zero level increases the effective signal-to-noise ratio (SNR) and enhances communication capacity without increasing the average power requirement.FIG. 2 presents a block diagram of a Signal Transmission and Reconstruction System (200) in accordance with an embodiment of the present invention. The system comprises an Input bits Source (205), an Encoder (210), a Voltage Level Converter (215), a Modulator (220), a Transmission Channel (225), a Demodulator (230), a Signal Reconstructor (235), a Decoder (240), and an Output Signal Source (245), as described below.

[0071] In one embodiment, the Input bits Source (205) is configured to generate an input bits that serves as the original data or information to be transmitted. The input bits may comprise analog or digital data, which can include voice, video, text, or any other form of communication data. The generated input bits is subsequently provided to the Encoder (210).

[0072] The Encoder (210) receives the input bits from the Input Source and processes it to encode the data in a format suitable for transmission. The encoding process may involve source coding, channel coding, or errorcorrection coding techniques to ensure that the transmitted signal can be accurately reconstructed at the receiver end. The encoded bits is then supplied to the Voltage Level Converter (215).

[0073] The Voltage Level Converter (215) is configured to convert the encoded bits into discrete voltage levels corresponding to the modulation scheme employed. Unlike conventional systems that use uniform voltage spacing between levels, the present invention utilizes non-uniform voltage spacing while maintaining a constant power difference between adjacentlevels. This ensures improved noise immunity and consistent signal detection accuracy. The converted level or signal is provided to the Modulator (220).

[0074] The Modulator (220) receives the converted signal and modulates it onto a carrier signal for transmission. The modulation technique employed may include amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), quadrature amplitude modulation (QAM), or any other suitable modulation method. The modulated signal is then transmitted through the Transmission Channel (225).

[0075] The Transmission Channel (225) represents the medium through which the modulated signal propagates. The channel may include a wireless communication link, a wired connection, or an optical fiber transmission path. As the signal traverses the channel, it is subjected to various forms of noise and distortion, represented by the noise component. Noise may originate from thermal noise, intermodulation interference, phase noise, and other channel impairments. The signal-to-noise ratio (SNR) within the channel determines the degree of signal degradation and the effectiveness of subsequent demodulation and reconstruction. Lower SNR values lead to increased error rates and reduced signal clarity.

[0076] The Demodulator (230) receives the transmitted signal from the Transmission Channel (225) and extracts the baseband signal by removing the carrier component. The demodulated signal retains the discrete levels defined by the modulation scheme but may be corrupted by noise. Noisemanifests as amplitude distortion, phase shifts, and signal attenuation, which can affect signal clarity and detection accuracy. The extracted signal is subsequently supplied to the Signal Reconstructor (235).

[0077] The Signal Reconstructor (235) processes the demodulated signal to recover the original signal levels. This includes correcting for noise-induced errors, signal distortion, and amplitude fluctuations. The reconstruction algorithm ensures that the constant power difference between adjacent levels is maintained, thereby improving the accuracy and reliability of the reconstructed signal. The noise immunity of the system is enhanced by the non-uniform voltage spacing combined with constant power difference, which allows the system to distinguish signal levels even under low SNR conditions. The reconstructed signal is then forwarded to the Decoder (240).

[0078] The Decoder (240) receives the reconstructed signal and decodes the data based on the encoding scheme applied at the transmitter. The decoding process may involve error correction and data recovery techniques to ensure that the output data matches the original input bits. The decoder may use parity-check codes, turbo codes, or low-density parity-check (LDPC) codes to correct bit errors introduced by noise during transmission. The decoded signal is subsequently provided to the Output Signal Source (245).

[0079] The Output Signal Source (245) generates the final output signal, which corresponds to the original input data after transmission andreconstruction. The output signal may be delivered as an analog or digital signal, depending on the application requirements.

[0080] FIG. 3 illustrates a flowchart detailing a Modulation Process (300) according to one embodiment of the present invention. The process includes a series of steps configured to encode, modulate, and transmit input bits for communication over a transmission channel, thereby improving signal fidelity, noise immunity, and communication capacity.

[0081] In one embodiment, the modulation process begins at step 305, where a modulation operation is initiated. At step 310, the system receives and converts input bits into a format suitable for encoding and modulation. The input bits may comprise analog or digital data, including but not limited to voice, video, text, or other communication sources. The conversion process may include digitization, sampling, and quantization, depending on the nature of the input sources and the transmission requirements.

[0082] At step 315, the system determines whether encoding is required for the input bits. The encoding decision may be based on system configuration parameters, channel conditions, and the desired level of error correction and noise immunity. If encoding is not required, the process directly proceeds to step 340 for voltage level mapping, bypassing the encoding process. If encoding is required, the process proceeds to any one of the encoding methods, including Block Encoding, Convolution Encoding, Turbo Encoding, or Low-Density Parity-Check (LDPC) Encoding, as described below.At step 320, the system performs Block Encoding. It involves segmenting the input bits into fixed-size blocks and applying error correction codes to each block. The block encoding process improves noise immunity and enhances the ability of the system to detect and correct transmission errors. Block encoding methods may include, but are not limited to, Hamming codes, Reed-Solomon codes, and cyclic redundancy checks (CRC).

[0083] At step 325, the system performs Convolution Encoding. It involves processing the input bits using a shift register-based scheme, where input bits are combined with previous state information to generate encoded output bits. Convolution encoding improves error correction performance and signal integrity, especially in noisy transmission environments. The encoding scheme may include Viterbi decoding or other trellis-based techniques.

[0084] At step 330, the system performs Turbo Encoding. It involves interleaving the input bits and applying parallel convolutional encoding to improve error correction and minimize bit error rates (BER). Turbo encoding is particularly effective in low signal-to-noise ratio (SNR) environments and enhances the overall performance of the communication system.

[0085] At step 335, the system optionally performs Low-Density Parity-Check (LDPC) Encoding. It involves generating a parity-check matrix to encode the input bits using low-density parity constraints. LDPC encoding provides high error correction performance and is suitable for high-throughput communication systems and noisy transmission channels. The selection of LDPC encoding may depend on the available processing power and the desired balance between encoding complexity and error correction performance.

[0086] At step 340, the system performs Voltage Level Mapping. The encoded bits is mapped to discrete voltage levels based on a predefined modulation scheme. In one embodiment, the voltage levels are mapped using non-uniform voltage spacing while maintaining a constant power difference between adjacent levels. This mapping approach improves noise immunity, signal detection accuracy, and communication capacity by enhancing the ability of the system to distinguish between adjacent signal levels under varying channel conditions. Non-uniform voltage spacing reduces the likelihood of symbol errors caused by noise, thereby improving the overall signal-to-noise ratio (SNR) of the transmission.

[0087] At step 345, the system performs Quadrature Amplitude Modulation (QAM). The mapped signal is modulated onto a carrier signal using QAM, where both the amplitude and phase of the carrier signal are varied based on the mapped voltage levels. QAM modulation enables high spectral efficiency and increased data transmission rates. The QAM scheme may include, but is not limited to, 16-QAM, 64-QAM, and 256-QAM, depending on system requirements and channel conditions. The choice of QAM order is dynamically adjustable based on real-time channel state information (CSI) to optimize transmission performance under changing channel conditions.At step 350, the system transmits the modulated signal over a transmission channel or over different sub-carriers. The transmission channel may comprise a wireless medium, a wired connection, or an optical fiber link. The transmitted signal may be subjected to noise, interference, and other channel impairments during propagation. Noise sources may include thermal noise, phase noise, and interference from adjacent channels. The system may include adaptive equalization, error correction, and signal recovery techniques to mitigate the effects of channel distortion and enhance overall transmission performance. Additionally, forward error correction (FEC) techniques may be employed at the receiver side to further improve signal fidelity.

[0088] FIG. 4 illustrates a flowchart detailing a Demodulation Process (400) according to one embodiment of the present invention. The process includes a sequence of steps configured to receive, demodulate, and decode transmitted signals, thereby reconstructing the original input bits with high fidelity and noise immunity.

[0089] In one embodiment, the demodulation process begins at step 405, where a demodulation operation is initiated. This initiation step may be triggered by a signal reception event or a command from a control unit within the communication system. The initiation of the demodulation process sets the operational parameters and prepares the system for signal reception and processing.At step 410, the system receives signals over a transmission channel. The received signals may be subject to noise, interference, and signal distortion due to channel impairments, multipath propagation, and other environmental factors. The system includes adaptive filtering and signal conditioning circuitry to preprocess the received signals and mitigate the effects of noise and distortion before further processing.

[0090] At step 415, the system demodulates the received signals from one carrier or many sub-carriers. Demodulation involves extracting the baseband signal from the carrier signal using a quadrature amplitude modulation (QAM) scheme. The demodulation process includes phase correction, amplitude recovery, and symbol timing recovery to accurately reconstruct the transmitted signal constellation. The QAM demodulation scheme may include, but is not limited to, 16-QAM, 64-QAM, and 256-QAM, depending on the modulation order and system configuration.

[0091] At step 420, the system retrieves the voltage levels corresponding to the demodulated signal symbols. The retrieved voltage levels reflect the amplitude and phase information of the transmitted signal. The system includes a symbol mapping module that converts the received signal points into discrete voltage levels based on a predefined signal constellation. The system uses non-uniform voltage spacing to enhance noise immunity and improve the signal-to-noise ratio (SNR) under varying channel conditions.

[0092] At step 425, the system converts the retrieved voltage levels into original bits. The conversion process involves reverse mapping the voltagelevels to the original data symbols. The system applies signal normalization and error correction techniques to compensate for channel-induced distortions and symbol errors.

[0093] At step 430, the system determines whether decoding is required for the recovered signals. The decoding decision is based on system configuration parameters, channel conditions, and the encoding scheme used during signal transmission. If decoding is not required, the process directly proceeds to step 455 to output the reconstructed bits. If decoding is required, the process proceeds to one or more decoding operations, which may include block decoding (435), convolution decoding (440), turbo decoding (445), and / or LDPC decoding (450).

[0094] At step 435, the system performs Block Decoding. Block decoding involves processing fixed-size blocks using error correction codes to detect and correct transmission errors. The block decoding scheme may include Hamming codes, Reed-Solomon codes, cyclic redundancy checks (CRC), and other block-based error correction methods. Block decoding enhances noise immunity and improves the reliability of bit reconstruction in the presence of transmission errors.

[0095] At step 440, the system performs Convolution Decoding. Convolution decoding involves processing the received bits using a trellis-based decoding scheme, where the system combines the current signal state with previous state information to correct transmission errors. The convolution decoding scheme may include Viterbi decoding or other maximum likelihooddecoding techniques to improve signal fidelity and reduce bit error rates (BER).

[0096] At step 445, the system performs Turbo Decoding. Turbo decoding involves iterative processing of the received bits using parallel convolutional codes and interleaving schemes. Turbo decoding improves error correction performance, particularly in low signal-to-noise ratio (SNR) environments. The system dynamically adjusts the number of decoding iterations based on the prevailing channel conditions to optimize error correction and minimize latency.

[0097] At step 450, the system optionally performs Low-Density Parity-Check (LDPC) Decoding. LDPC decoding involves processing the received bits using a parity-check matrix and an iterative belief propagation algorithm. LDPC decoding provides high error correction performance and is suitable for high-throughput communication systems. The system selects LDPC decoding based on the desired trade-off between decoding complexity and error correction performance.

[0098] At step 455, the system outputs the reconstructed bits. The reconstructed bits reflects the original input bits with enhanced fidelity and reduced transmission errors. The system includes an output buffer and a signal interface to deliver the reconstructed signal to the destination module or communication endpoint. The reconstructed bits may undergo additional post-processing, including equalization, noise suppression, and signalenhancement, to further improve the estimation quality and communication performance.

[0099] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

Claims

AMENDED CLAIMSreceived by the International Bureau on August 28, 2026 (28.08.2026) We Claim:

1. A method of modulation and demodulation, comprising:converting input bits into a set of non-uniformly spaced voltage levels, wherein the voltage levels are determined according to a signal-level index and a base signal voltage such that a constant power difference is maintained between adjacent voltage levels; andmodulating the converted bits for transmission.

2. The method as claimed in claim 1, wherein the power difference between adjacent voltage levels is determined based on noise characteristics of the communication channel.

3. The method as claimed in claim 1, wherein converting the input bits includes assigning voltage levels based on a predefined mapping strategy that relates the voltage levels to respective signal-level indices and the base signal voltage.

4. The method as claimed in claim 3, wherein the voltage levels include both positive and negative values, maintaining symmetry in signal representation.

5. The method as claimed in claim 1 , further comprising:encoding the input bits prior to converting them into non-uniformly spaced voltage levels.

6. The method as claimed in claim 5, wherein the encoding technique is selected from the group consisting of: block encoding, convolutional encoding, turbo encoding, and low-density parity-check (LDPC) encoding.

7. The method as claimed in claim 1 , wherein the modulating comprises quadrature amplitude modulation (QAM) of one or more sub-carriers, and the non-uniformly spaced voltage levels are applied to both in-phase and quadrature components.

8. A system for signal modulation, comprising:a converter configured to map input bits to non-uniformly spaced voltage levels, wherein the voltage levels are determined according to a signal-level index and a base signal voltage such that a constant power difference is maintained between adjacent voltage levels; anda modulator configured to modulate the mapped signals for transmission.

9. The system as claimed in claim 8, wherein the power difference between adjacent voltage levels is dynamically adjusted based on communication channel conditions.

10. The system as claimed in claim 8, wherein the converter is configured to assign voltage levels using a mapping strategy that relates the voltage levels to respective signal-level indices and a base signal voltage.

11. The system as claimed in claim 10, wherein the voltage levels include both positive and negative values, ensuring balanced signal representation.

12. The system as claimed in claim 8, further comprising an encoder configured to process input bits before mapping by the converter.

13. The system as claimed in claim 12, wherein the encoder is selected from the group consisting of: block encoding, convolutional encoding, turbo encoding, and low-density parity-check (LDPC) encoding.

14. The system as claimed in claim 8, wherein the modulator is configured to perform quadrature amplitude modulation (QAM) of one or more sub-carriers, with the irregularly spaced voltage levels applied to both in-phase and quadrature components.

15. A device for quadrature amplitude modulation, comprising:a signal generator configured to produce non-uniformly spaced voltage levels, wherein the voltage levels are determined according to a signal-level index and a base signal voltage such that a constant power difference is maintained between adjacent voltage levels; anda quadrature modulator configured to modulate the produced signals.

16. The device as claimed in claim 15, wherein the power difference between adjacent voltage levels is adjusted based on noise power and system requirements.

17. The device as claimed in claim 16, wherein the adjustment factor is predefined to ensure optimal signal performance.

18. The device as claimed in claim 15, wherein the signal generator assigns voltage levels using a structured mapping approach that relates the voltage levels to respective signal-level indices and a base signal voltage.

19. The device as claimed in claim 18, wherein the voltage levels include both positive and negative values, ensuring balanced modulation.

20. The device as claimed in claim 19, further comprising an encoder configured to process input bits before conversion by the signal generator, wherein the encoder is selected from the group consisting of: block encoding, convolutional encoding, turbo encoding, and low-density paritycheck (LDPC) encoding.

Images