Method, apparatus, and system for performing modulation and demodulation based on chirp spread spectrum technique

Abstract

A system and a method thereof for performing modulation and demodulation based on a chirp spread band technique are disclosed. A system for performing modulation and demodulation based on a chirp spread band technique according to one embodiment of the present disclosure includes: a transmitter that transmits a chirp signal; and a receiver that receives and demodulates the chirp signal. The transmitter determines the number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF), and transmits a first chirp signal obtained by modulating the first data bits in at least one symbol according to the determined number of data bits modulated in the unit symbol to the receiver. The receiver may transmit information indicating a second residual carrier frequency offset detected based on the received first chirp signal to the transmitter.

Description

Technology Field

[0001] The present disclosure relates to modulation and demodulation methods, apparatuses, and systems, and more specifically, to methods, apparatuses, and systems for performing modulation and demodulation in communication systems related to chirp spread spectrum. Background Technology

[0002] Chirp spread spectrum, a widely used technology in the field of IoT communication, offers the advantage of enabling low-cost long-distance communication due to its robustness against channel fading and noise. Recently, as the applications of chirp spread spectrum have expanded to include drones, automobiles, and trains, the performance of this technique in high-speed mobile environments is becoming increasingly important.

[0003] However, in high-speed moving environments, a problem may arise where the symbol error rate increases significantly due to the carrier frequency offset caused by Doppler shift, etc.

[0004] Although the receiver can perform an operation to compensate for the carrier frequency offset, errors may occur during the symbol demodulation process due to the residual carrier frequency offset. Therefore, there is a growing need for modulation and demodulation techniques to resolve the problem of increased error rates caused by the residual carrier frequency offset. The problem to be solved

[0005] The technical problem of the present disclosure is to provide a modulation and demodulation method and apparatus to solve the problem of increased error rate due to residual carrier frequency offset in a chirp spread-spectrum modulation wireless communication system.

[0006] The technical problem of the present disclosure is to provide a modulation and demodulation method and apparatus for controlling the number of bits modulated in a transmitted symbol of a wireless communication system using a chirp spread-spectrum modulation method.

[0007] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below. means of solving the problem

[0008] In one embodiment of the present disclosure, a system for performing modulation and demodulation based on a chirp band spreading technique comprises: a transmitter that transmits a chirp signal; and a receiver that receives and demodulates the chirp signal, wherein the transmitter determines the number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF), and transmits a first chirp signal obtained by modulating the first data bits in at least one symbol according to the determined number of data bits modulated in the unit symbol to the receiver, and the receiver can transmit information indicating a second residual carrier frequency offset detected based on the received first chirp signal to the transmitter.

[0009] And, the transmitter can determine the number of data bits to be modulated in the unit symbol according to the second residual carrier frequency offset, and transmit the second chirp signal obtained by modulating the second data bits in at least one symbol through the determined number of data bits to be modulated in the unit symbol to the receiver.

[0010] And, the transmitter determines the number of data bits (M) modulated to the unit symbol according to Equation 1, wherein Equation 1 is, and, in the above mathematical formula 1, f CFO may be the above-mentioned first residual carrier frequency value.

[0011] And, the transmitter may include at least one of an encoder; a data whitening processor; an interleaver; a gray mapping processor; and a modulator.

[0012] And, the encoder performs Hamming encoding on the first input data to detect and correct bit errors associated with the first input data, the data whitening processor removes the correlation between bits corresponding to the first input data that has undergone Hamming encoding, the interleaver distributes consecutive bit errors on the first input data from which the correlation between bits has been removed, and the gray mapping processor performs gray mapping on the first input data processed by the interleaver to output the first data.

[0013] And, the receiver may include at least one of a synchronization processor; a decoder; a data dewhitening processor; a de-interleaver; a gray demapping processor; and a demodulator.

[0014] And, the receiver transmits information to the transmitter regarding whether the symbol error rate due to the second residual carrier frequency offset exceeds the first threshold value, and the transmitter may increase the second residual carrier frequency offset by a predefined value based on receiving information from the receiver indicating that the symbol error rate exceeds the first threshold value.

[0015] And, the synchronization processor may perform synchronization processing for the first chirp signal and, based on the symbol error rate of the first chirp signal that performed the synchronization processing exceeding a second threshold, transmit information indicating the second residual carrier frequency offset to the transmitter.

[0016] In one embodiment of the present disclosure, a method for performing modulation and demodulation based on a chirp band spread technique, performed by a transmitter and a receiver, may include: a step of determining, by the transmitter, a number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF); a step of transmitting to the receiver a first chirp signal obtained by modulating the first data bits in at least one symbol according to the number of data bits modulated in the unit symbol determined by the transmitter; and a step of transmitting to the transmitter information indicating a second residual carrier frequency offset detected based on the received first chirp signal by the receiver.

[0017] The features briefly summarized above regarding the present disclosure are merely exemplary aspects of the detailed description of the present disclosure that follows and do not limit the scope of the present disclosure. Effects of the invention

[0018] By various embodiments of the present disclosure, a method and apparatus for performing modulation and demodulation in a wireless communication system using a chirp spread-spectrum modulation scheme may be provided.

[0019] By various embodiments of the present disclosure, the problem of increased error rate due to residual carrier frequency offset can be solved by adjusting the number of bits modulated in the transmission symbol of a wireless communication system using a chirp spread band modulation method.

[0020] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below. Brief explanation of the drawing

[0021] FIG. 1 is a diagram illustrating the configuration of a transceiver / receiver on a chirp-spread-band-based wireless communication system according to one embodiment of the present disclosure. FIG. 2 is a flowchart illustrating a method for performing modulation and demodulation based on a chirp band spreading technique according to one embodiment of the present disclosure. FIG. 3 is a block diagram illustrating the configuration of a device that performs modulation and demodulation based on a chirp band spreading technique according to one embodiment of the present disclosure. Specific details for implementing the invention

[0022] The present disclosure is subject to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure. Similar reference numerals in the drawings refer to the same or similar functions across various aspects. The shapes and sizes of elements in the drawings may be exaggerated for clearer explanation. The detailed description of exemplary embodiments described below refers to the accompanying drawings, which illustrate specific embodiments as examples. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments. It should be understood that various embodiments are different but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present disclosure in relation to one embodiment. It should also be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the embodiment. Accordingly, the following detailed description is not intended to be taken in a limiting sense, and the scope of exemplary embodiments is limited only by the appended claims, together with all equivalents to those claimed therein, provided they are properly described.

[0023] In this disclosure, terms such as first, second, etc. may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of this disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0024] Where it is stated that any component of the present disclosure is "connected" or "connected" to another component, it should be understood that it may be directly connected to or connected to the other component, or that there may be other components in between. On the other hand, where it is stated that a component is "directly connected" to or "directly connected" to another component, it should be understood that there are no other components in between.

[0025] The components shown in the embodiments of the present disclosure are depicted independently to represent different characteristic functions and do not imply that each component consists of separate hardware or a single software unit. That is, each component is listed and included as a separate component for convenience of explanation; however, at least two of the components may be combined to form a single component, or a single component may be divided into multiple components to perform a function, and such integrated and separated embodiments of each component are included within the scope of the rights of the present disclosure as long as they do not depart from the essence of the present disclosure.

[0026] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit this disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this disclosure, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. That is, the description in this disclosure that a specific configuration "comprising" does not exclude configurations other than that configuration, but means that additional configurations may be included within the scope of the practice or technical concept of this disclosure.

[0027] Some components of the present disclosure may not be essential components performing an essential function in the present disclosure, but may be optional components merely for enhancing performance. The present disclosure may be implemented by including only the components essential to embody the essence of the present disclosure, excluding components used merely for enhancing performance, and a structure including only the essential components, excluding optional components used merely for enhancing performance, is also included within the scope of the rights of the present disclosure.

[0028] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In describing the embodiments of this specification, if it is determined that a detailed description of related known configurations or functions may obscure the gist of this specification, such detailed description is omitted, and the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0030] The system and / or method / device proposed in this disclosure (hereinafter simply referred to as the "system") relates to a technique for performing modulation and demodulation in a chirp-spread-band-based wireless communication system.

[0031] As an example of the present disclosure, as illustrated in FIG. 1, a chirp spread-spectrum-based wireless communication system may be composed of a transmitter and a receiver.

[0032] Here, the transmitter and receiver may be included in a single device, but are not limited thereto, and the transmitter and receiver may each be configured as separate devices.

[0033] For example, the transmitter can perform Hamming encoding, data whitening, gray mapping, and chirp spread modulation on the input data bits.

[0034] The transmitter may include separate modules for performing Hamming encoding, data whitening, gray mapping, and chirp spread band modulation, respectively, but is not limited thereto. The transmitter may include an integrated module for performing Hamming encoding, data whitening, gray mapping, and chirp spread band modulation.

[0035] As another example, data output by a transmitter can be transmitted through a specific channel. In this case, noise may be added to the data output by the transmitter.

[0036] The receiver can acquire data bits by performing synchronization, chirp spread spectrum demodulation, Gray demapping, de-interleaving, data de-whitening, and Hamming decoding on the data output by the transmitter to which noise has been added.

[0037] The receiver may include, but is not limited to, separate modules for performing synchronization, chirp-spread band demodulation, Gray demapping, deinterleaving, data dewhitening, and Hamming decoding, respectively. The receiver may include an integrated module for performing synchronization, chirp-spread band demodulation, Gray demapping, deinterleaving, data dewhitening, and Hamming decoding.

[0038] Here, the Hamming encoding and decoding processes may include operations for detecting and correcting bit errors. The data whitening and dewhitening processes may include operations for removing correlations between adjacent bits. The Gray demapping process may include operations for minimizing bit errors caused by frequency offsets.

[0039] Additionally, the chirp-spread band modulation process may include an operation of converting a symbol to be transmitted into a chirp signal. The chirp-spread band reporting process may include an operation of converting a received chirp signal into a symbol to be received.

[0041] The following describes the chirp spread spectrum modulation and demodulation processes in a basic wireless communication system.

[0042] A chirp spread signal in which information is modulated at the starting frequency of the chirp signal can be expressed as Equation 1.

[0043]

[0044] Here, represents the spreading factor. represents the transmission symbol. a c is an SF beat ' It can be calculated according to mathematical formula 2 using '.

[0045]

[0046] If a residual carrier frequency offset exists even after the synchronization process of the receiver in Fig. 1, the received signal can be expressed as in Equation 3.

[0047]

[0048] Here, represents the residual carrier frequency offset, and can refer to additive white Gaussian noise. In the receiver, the received signal is Using this, the symbol can be demodulated as in mathematical formula 4.

[0049]

[0050] Here, represents the complex conjugate operation, and It can be expressed as in mathematical formula 5.

[0051]

[0052] In the case of the modulation method in the basic wireless communication system described above, as shown in Equation 1 Bit symbol ( ) can be modulated to the frequency of the chirp signal.

[0053] Accordingly, the magnitude of the residual carrier frequency offset ( Assume the case where ) is large. When the demodulation process according to Equation 4 is performed, ' ' or ' Problems may occur where the symbol is incorrectly demodulated to an adjacent symbol on the frequency plane, such as '.

[0054] Below, we will explain a modulation and demodulation method capable of resolving the aforementioned symbol error problem.

[0056] FIG. 2 is a flowchart illustrating a method for performing modulation and demodulation based on a chirp band spreading technique according to one embodiment of the present disclosure.

[0057] Specifically, FIG. 2 is a flowchart for explaining the operation of a system in which a transmitter and a receiver shown in FIG. 1 perform modulation and demodulation based on a chirp spread band technique. Here, the transmitter refers to a device that transmits a chirp signal generated by modulating input data, and the receiver refers to a device that receives the chirp signal transmitted from the transmitter.

[0058] The transmitter may include at least one of an encoder, a data whitening processor, an interleaver, a gray mapping processor, and a modulator.

[0059] For example, the encoder can detect and correct bit errors associated with the first input data by performing Hamming encoding on the first input data.

[0060] The data whitening processor can remove the correlation between bits corresponding to the first input data that has undergone Hamming encoding (i.e., the correlation between each bit constituting the first input data) by performing a data whitening operation.

[0061] The interleaver can distribute consecutive bit errors on the first input data from which inter-bit correlation has been removed (i.e., errors detected on consecutive bits among the bits constituting the first input data).

[0062] The gray mapping processor can perform gray mapping on the first input data processed by the interleaver and output the first data.

[0063] The modulator determines the number of data bits to be modulated in a unit symbol and can modulate the first data into at least one symbol according to the number of data bits to be modulated in the determined unit symbol.

[0064] The receiver may include at least one of a synchronization processor, a decoder, a data dewhitening processor, a de-interleaver, a gray demapping processor, and a demodulator.

[0065] The synchronization processor can perform the role of compensating for the carrier frequency offset on the chirp signal by applying a synchronization process to the chirp signal transmitted from the transmitter.

[0066] Each of the decoder, data dewhitening processor, de-interleaver, gray demapping processor, and demodulator can perform an operation corresponding to the encoder, data whitening processor, interleaver, gray mapping processor, and modulator included in the transmitter. That is, the receiver can restore / decode the first input data by demodulating the chirp signal.

[0067] The transmitter can determine the number of data bits modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF) (S210).

[0068] That is, the transmitter can dynamically determine the number of data bits modulated for (or on) a unit symbol based on the first residual carrier frequency offset and the SF value.

[0069] Here, the first residual carrier frequency offset may be a predefined default value. As another example, the first residual carrier frequency offset may be transmitted from the receiver to the transmitter.

[0070] For example, the transmitter can determine / control the number of data bits modulated for a unit symbol according to Equation 9 described below. In Equation 9, f CFO can be the first residual carrier frequency value.

[0071] The transmitter can transmit a first chirp signal obtained by modulating a first data bit to at least one symbol according to the number of data bits modulated to a determined unit symbol (S220).

[0072] The receiver can transmit the second residual carrier frequency offset detected based on the received first chirp signal to the transmitter (S230).

[0073] The transmitter can (re)determine the number of data bits modulated in a unit symbol according to the second residual carrier frequency offset. The transmitter can transmit the second chirp signal obtained by modulating the second data bits in at least one symbol through the determined number of data bits modulated in the unit symbol to the receiver.

[0074] That is, the transmitter can change the number of bits modulated in the symbol according to network conditions (e.g., the magnitude of the residual carrier frequency offset value detected based on the signal received at the receiver).

[0075] In addition, the transmitter can increase the frequency spacing between adjacent symbols by adjusting the number of bits modulated in a symbol to a value smaller than the spreading factor. Accordingly, symbol errors caused by residual carrier frequency offset can be reduced.

[0076] In one example of the present disclosure, a receiver can detect whether the symbol error rate due to a second residual carrier frequency offset exceeds a first threshold. The receiver can then transmit information regarding whether the symbol error rate due to the second carrier frequency offset exceeds the first threshold to a transmitter.

[0077] Based on receiving information from the receiver indicating that the symbol error rate exceeds a first threshold value, the transmitter may increase the second residual carrier frequency offset by a predefined value. That is, if the symbol error rate is detected to be a large value, the transmitter may increase the second residual carrier frequency offset by a predefined value and then use the second residual carrier frequency offset to determine the number of data bits modulated in a unit symbol.

[0078] Accordingly, the transmitter can reduce the symbol error rate generated at the receiver.

[0079] Additionally or alternatively, a synchronization processor included in the receiver can perform synchronization processing for the first chirp signal.

[0080] Based on the fact that the symbol error rate of the first chirp signal, on which synchronization processing has been performed, exceeds a second threshold value, the transmitter may transmit a second residual carrier frequency offset (i.e., information indicating the second residual carrier frequency offset) to the transmitter. That is, if the symbol error rate of the first chirp signal is detected to be a large value, the receiver may transmit the second residual carrier frequency offset to the transmitter to indicate that a change in the number of bits of data modulated in a single symbol is required.

[0081] As another example, based on the fact that the symbol error rate of the first chirp signal, which has undergone synchronization processing, is less than the second threshold value, the receiver may transmit only information indicating that the first chirp signal has been received to the transmitter, without transmitting information indicating the second residual carrier frequency offset value. When only information indicating that the first chirp signal has been received is received, the receiver may determine that the number of bits currently modulating per unit symbol is appropriate.

[0082] That is, by transmitting the second residual carrier frequency offset to the transmitter only when the symbol error rate of the first chirp signal, which has undergone synchronization processing, exceeds the second threshold, the overhead associated with data transmission and reception can be reduced.

[0084] Below, we will explain in more detail the modulation and demodulation method capable of resolving the aforementioned symbol error problem.

[0085] As an example of the present disclosure, the number of bits modulated in one symbol can be set to be smaller than the spreading factor (i.e., SF) to reduce the symbol error rate increased by the residual carrier frequency offset.

[0086] When modulating M bits of information in a single symbol, the transmitted symbol can be expressed as shown in Equation 6 below.

[0087]

[0088] At this time, represents a transmission symbol according to one example of the present disclosure, and The range of is It can be determined as.

[0089] As in mathematical formula 6 A symbol consisting of bits of information It can be demodulated at the receiver as in Equation 7.

[0090]

[0091] In mathematical formula 7 It can be expressed as in mathematical formula 8.

[0092]

[0093] As an example of the present disclosure, since a number of bits smaller than SF is modulated as in Equation 6, the frequency spacing between adjacent symbols may be wider than the modulation method in a basic wireless communication system.

[0094] That is, in Equation 2, the frequency interval between adjacent symbols is 1, whereas in Equation 6, the frequency interval between adjacent symbols is am.

[0095] The modulation scheme according to the example described above in the present disclosure can have stronger performance against residual carrier frequency offset than the modulation scheme in a basic wireless communication system. That is, by using the modulation scheme according to the example described above in the present disclosure The symbol error rate increased by can be reduced.

[0096] In mathematical equation 6, parameter M can be set according to various methods. Parameter The smaller this value is, the greater the advantage of significantly reducing the symbol error rate due to residual carrier frequency offset, but there is also the disadvantage of a lower data transmission rate. In other words, the parameter Since the increase or decrease in size has a trade-off relationship, the size of parameter M must be set appropriately.

[0097] In one example of the present disclosure, the frequency spacing between adjacent symbols is Parameter M can be set to become a larger value.

[0098] For example, when parameter M is set as in mathematical formula 9, it is possible to secure an appropriate level of data transmission rate while significantly reducing the probability that information is incorrectly demodulated to adjacent symbols.

[0099]

[0101] FIG. 3 is a block diagram illustrating the configuration of a device that performs modulation and demodulation based on a chirp band spreading technique according to one embodiment of the present disclosure.

[0102] Referring to FIG. 3, the device (100) may represent a device that performs modulation and demodulation based on the chirp band spreading technique described in the present disclosure.

[0103] For example, the device (100) can reduce the symbol error rate increased by the residual carrier frequency offset by setting the number of bits modulated in one symbol to be smaller than SF.

[0104] In chirp-spread-based modulation and demodulation schemes in basic wireless communication systems, the number of bits modulated per symbol is set to a fixed value, so if the residual carrier frequency offset is large, the symbol error rate may increase.

[0105] To resolve this, if the device (100) sets the number of bits modulated in a single symbol to a small value, the frequency spacing between symbols becomes wider, so the symbol error caused by residual carrier frequency offset can be reduced. That is, when the device (100) performs according to the method described above, the symbol error rate can be reduced by variably adjusting the number of bits modulated in a single symbol.

[0106] For example, the device (100) can determine the number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF).

[0107] The device (100) may include at least one of a processor (110), memory (120), a transceiver (130), an input interface device (140), and an output interface device (150). Each component may be connected by a common bus (160) to communicate with each other. Additionally, each component may be connected via an individual interface or an individual bus centered around the processor (110), rather than via the common bus (160).

[0108] The processor (110) can be implemented in various types such as an Application Processor (AP), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), etc., and can be any semiconductor device that executes instructions stored in memory (120). The processor (110) can execute program instructions stored in memory (120). The processor (110) can be configured to perform modulation and demodulation based on the chirp spread spectrum technique described above with reference to FIGS. 1 and 2.

[0109] The processor (110) may include one or more modules for performing modulation and demodulation based on the chirp spread band technique. For example, the processor (110) of the transmitter may control an encoder, a data whitening processor, an interleaver, a gray mapping processor, and a modulator. And, the processor (110) of the receiver may control a synchronization processor, a decoder, a data dewhitening processor, a deinterleaver, a gray demapping processor, and a demodulator.

[0110] And / or, the processor (110) may store program instructions in memory (120) for implementing at least one function for one or more modules to control the operation described based on FIGS. 1 and 2 to be performed. That is, each operation and / or function according to FIGS. 1 and 2 may be executed by one or more processors (110).

[0111] The memory (120) may include various forms of volatile or non-volatile storage media. For example, the memory (120) may include ROM (read-only memory) and RAM (random access memory). In an embodiment of the present disclosure, the memory (120) may be located inside or outside the processor (110), and the memory (120) may be connected to the processor (110) through various known means.

[0112] For example, the memory (120) can store data related to a module for performing modulation and demodulation based on a chirp spread band technique. Additionally, the memory (120) can store one or more parameters related to operations performed in the transceiver (130).

[0113] The transmitting and receiving unit (130) can perform the function of transmitting and receiving data processed / to be processed by the processor (110) to and from an external device and / or external system.

[0114] For example, the transceiver (130) can be used for data exchange with other terminal devices, etc. As an example, the transceiver (130) can transmit and receive a chirp signal and / or a residual carrier frequency offset. As another example, the transceiver (130) can transmit and receive information indicating that a chirp signal has been received.

[0115] The input interface device (140) is configured to provide data to the processor (110).

[0116] The output interface device (150) is configured to output data from the processor (110).

[0118] The components described in the exemplary embodiments of the present disclosure may be implemented by hardware elements. For example, the hardware elements may include at least one of a digital signal processor (DSP), a processor, a controller, an application-specific integrated circuit (ASIC), a programmable logic element such as an FPGA, a GPU, other electronic devices, or a combination thereof. At least some of the functions or processes described in the exemplary embodiments of the present disclosure may be implemented in software, and the software may be recorded on a recording medium. The components, functions, and processes described in the exemplary embodiments may be implemented by a combination of hardware and software.

[0119] A method according to one embodiment of the present disclosure may be implemented as a program that can be executed by a computer, and said computer program may be recorded on various recording media such as magnetic storage media, optical reading media, digital storage media, etc.

[0120] The various technologies described in this disclosure may be implemented as digital electronic circuits or computer hardware, firmware, software, or a combination thereof. The technologies may be implemented as computer program products, namely, computer programs tangibly implemented on information media or computer programs (e.g., machine-readable storage devices (e.g., computer-readable media) or data processing devices), or as computer programs implemented as signals processed by or propagated to perform operations of data processing devices (e.g., programmable processors, computers, or a plurality of computers).

[0121] Computer program(s) may be written in any form of programming language, including compiled or interpreted languages, and may be distributed in any form, including standalone programs or modules, components, subroutines, or other units suitable for use in a computing environment. Computer programs may be executed on a single computer, or by multiple computers distributed across one site or multiple sites and interconnected by a communication network.

[0122] Examples of processors suitable for executing computer programs include general-purpose and special-purpose microprocessors, and one or more processors of a digital computer. Generally, a processor receives instructions and data from read-only memory or random access memory, or both. Components of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Additionally, the computer may include one or more mass storage devices for storing data, such as magnetic, magneto-optical disks, or optical disks, or may be connected to said mass storage devices to receive and / or transmit data. Examples of information media suitable for implementing computer program instructions and data include semiconductor memory devices (magnetic media such as hard disks, floppy disks, and magnetic tapes), optical media such as compact disc read-only memory (CD-ROM) and digital video discs (DVD), magneto-optical media such as floptical disks, and Read Only Memory (ROM), Random Access Memory (RAM), flash memory, Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), and other known computer-readable media. Processors and memory may be complemented or integrated by special-purpose logic circuits.

[0123] A processor may execute an operating system (OS) and one or more software applications running on the OS. A processor unit may also access, store, manipulate, process, and generate data in response to software execution. For simplification, a processor unit is described in the singular; however, those skilled in the art will understand that the processor unit may include multiple processing elements and / or various types of processing elements. For example, a processor unit may include multiple processors or a processor and a controller. It may also constitute different processing structures, such as parallel processors. Furthermore, a computer-readable medium means any medium accessible to a computer and may include both computer storage media and transmission media.

[0124] The present disclosure includes detailed descriptions of various detailed embodiments, but such details are not intended to limit the invention or claims proposed in the present disclosure and should be understood as describing the features of specific exemplary embodiments.

[0125] Features individually described in exemplary embodiments in this disclosure may be implemented by a single exemplary embodiment. Conversely, various features described with respect to a single exemplary embodiment in this disclosure may be implemented by a combination of multiple exemplary embodiments or a suitable sub-combination. Furthermore, in this disclosure, said features may operate by a specific combination and may be described as said combination first claimed, but in some cases, one or more features may be excluded from the claimed combination, or the claimed combination may be changed into a sub-combination or a modified form of a sub-combination.

[0126] Likewise, even if operations are described in a specific order in the drawings, it should not be understood that it is necessary to execute the operations in a specific sequence or order, or that all operations must be performed, in order to obtain the desired result. In certain cases, multitasking and parallel processing may be useful. Furthermore, it should not be understood that the various device components in the exemplary embodiments of all embodiments must be separated, and the aforementioned program components and devices may be packaged into a single software product or multiple software products.

[0127] The exemplary embodiments disclosed in this specification are merely illustrative and are not intended to limit the scope of this disclosure. Those skilled in the art will recognize that various modifications to the exemplary embodiments may be made without departing from the spirit and scope of the claims and their equivalents.

[0128] Accordingly, the present disclosure shall be deemed to include all other substitutions, modifications, and changes falling within the scope of the following claims. Explanation of the symbols

[0129] 100 : Device 110 : Processor 120 : Memory 130 : Transmitter / Receiver 140: Input interface device 150: Output interface device 160 : Common bus

Claims

Claim 1 A system for performing modulation and demodulation based on a chirp spread band technique, wherein the system comprises: a transmitter for transmitting a chirp signal; and a receiver for receiving and demodulating the chirp signal, wherein the transmitter determines the number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF), and transmits to the receiver a first chirp signal obtained by modulating the first data bits in at least one symbol according to the number of data bits modulated in the unit symbol determined, and the receiver transmits to the transmitter information indicating a second residual carrier frequency offset detected based on the received first chirp signal. Claim 2 A system according to claim 1, wherein the transmitter determines the number of data bits to be modulated in the unit symbol according to the second residual carrier frequency offset, and transmits to the receiver a second chirp signal obtained by modulating the second data bits in at least one symbol through the number of data bits to be modulated in the unit symbol determined. Claim 3 In claim 1, the transmitter determines the number of data bits (M) modulated to the unit symbol according to Equation 1, wherein Equation 1 is, and, in the above mathematical formula 1, f CFO is the system, which is the first residual carrier frequency value above. Claim 4 A system according to claim 1, wherein the transmitter comprises at least one of an encoder; a data whitening processor; an interleaver; a gray mapping processor; and a modulator. Claim 5 A system according to claim 4, wherein the encoder performs Hamming encoding on the first input data to detect and correct bit errors associated with the first input data, the data whitening processor removes the correlation between bits corresponding to the first input data that has undergone Hamming encoding, the interleaver disperses consecutive bit errors on the first input data from which the correlation between bits has been removed, and the gray mapping processor performs gray mapping on the first input data processed by the interleaver to output the first data. Claim 6 A system according to claim 1, wherein the receiver comprises at least one of a synchronization processor; a decoder; a data dewhitening processor; a de-interleaver; a gray demapping processor; and a demodulator. Claim 7 A system according to claim 1, wherein the receiver transmits information to the transmitter regarding whether the symbol error rate due to the second residual carrier frequency offset exceeds a first threshold value, and the transmitter increases the second residual carrier frequency offset by a predefined value based on receiving information from the receiver indicating that the symbol error rate exceeds the first threshold value. Claim 8 A system according to claim 6, wherein the synchronization processor performs synchronization processing for the first chirp signal and transmits information indicating the second residual carrier frequency offset to the transmitter based on the symbol error rate of the first chirp signal that performed the synchronization processing exceeding a second threshold value. Claim 9 A method for performing modulation and demodulation based on a chirp band spread technique, performed by a transmitter and a receiver, wherein the method comprises: a step of determining, by the transmitter, the number of data bits (M) modulated in a unit symbol based on a first residual carrier frequency offset and a spreading factor (SF); a step of transmitting to the receiver a first chirp signal obtained by modulating the first data bits in at least one symbol according to the number of data bits modulated in the unit symbol determined by the transmitter; and a step of transmitting to the transmitter information indicating a second residual carrier frequency offset detected based on the received first chirp signal by the receiver. Claim 10 A method according to claim 9, wherein the number of data bits modulated in the unit symbol according to the second residual carrier frequency offset is determined by the transmitter, and the second chirp signal obtained by modulating the second data bits in at least one symbol through the number of data bits modulated in the unit symbol determined by the transmitter is transmitted to the receiver. Claim 11 In claim 9, the number of data bits (M) modulated in the unit symbol is determined according to Equation 1, and Equation 1 is, and, in the above mathematical formula 1, f CFO is the first residual carrier frequency value above, method. Claim 12 In claim 9, the method comprises at least one of the transmitter, an encoder; a data whitening processor; an interleaver; a gray mapping processor; and a modulator. Claim 13 In claim 12, the encoder performs Hamming encoding on the first input data to detect and correct bit errors associated with the first input data, the data whitening processor removes the correlation between bits corresponding to the first input data that has undergone Hamming encoding, the interleaver disperses consecutive bit errors on the first input data from which the correlation between bits has been removed, and the gray mapping processor performs gray mapping on the first input data processed by the interleaver to output the first data. Claim 14 In claim 9, the receiver comprises at least one of a synchronization processor; a decoder; a data dewhitening processor; a de-interleaver; a gray demapping processor; and a demodulator. Claim 15 A method according to claim 9, wherein the receiver transmits information to the transmitter regarding whether the symbol error rate due to the second residual carrier frequency offset exceeds a first threshold value, and the transmitter increases the second residual carrier frequency offset by a predefined value based on receiving information from the receiver indicating that the symbol error rate exceeds the first threshold value. Claim 16 A method according to claim 14, wherein the synchronization processor performs synchronization processing for the first chirp signal and transmits information indicating the second residual carrier frequency offset to the transmitter based on the symbol error rate of the first chirp signal that performed the synchronization processing exceeding a second threshold value.

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