Orthogonal frequency division multiplexing communication method, device and equipment based on two-dimensional index modulation

Abstract

The invention discloses an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, which is applied to a sending end and is used for acquiring a bit stream. An orthogonal frequency division multiplexing baseband signal is generated, the orthogonal frequency division multiplexing baseband signal carries pilot index bits, the pilot index bits comprise a position selection subset and a pilot modulation subset, the position selection subset is used for indicating pilot subcarrier positions, the pilot modulation subset is used for generating pilot modulation symbols, and the pilot index bits are determined based on a bit stream. And sending the orthogonal frequency division multiplexing baseband signal to a receiving end, so that the receiving end recovers the bit stream based on the orthogonal frequency division multiplexing baseband signal. According to an orthogonal frequency division multiplexing baseband signal modulated by a two-dimensional index, a pilot frequency position is indexed to communication information, meanwhile, a pilot frequency modulation symbol is loaded to realize pilot frequency information multiplexing, and a pilot frequency subcarrier position is taken as an information dimension to participate in index modulation, so that the transmission dimension is expanded on the premise of not increasing extra subcarriers, and the utilization rate of spectrum resources is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of communications, specifically relating to an orthogonal frequency division multiplexing communication method, apparatus, and device based on two-dimensional index modulation. Background Technology

[0002] With the rapid development of the Internet of Things (IoT), the massive number of low-power terminal devices has placed comprehensive demands on wireless communication systems, requiring high connection density, low power consumption, and high reliability. Orthogonal Frequency Division Multiplexing (OFDM) technology, due to its excellent resistance to multipath fading and ease of implementation, has been widely used in mainstream communication standards such as 4G LTE, 5G NR, and Wi-Fi. However, traditional OFDM requires activating all subcarriers for data or pilot transmission in each symbol period, resulting in limited spectrum resource utilization efficiency and fixed pilot overhead, making it difficult to meet the stringent energy efficiency and spectrum efficiency requirements of IoT scenarios.

[0003] To improve spectral efficiency, researchers have proposed OFDM with Index Modulation (OFDM-IM) technology. This technology increases transmission rates without increasing bandwidth by activating only a subset of subcarriers and encoding the "activation mode" as an additional information dimension. However, existing OFDM-IM schemes still have significant limitations: firstly, pilot subcarriers typically use fixed positions and known values, serving only for channel estimation and not participating in information carrying, resulting in a waste of valuable frequency domain resources; secondly, its index modulation only applies to the activation state of data subcarriers, constituting single-dimensional modulation, which struggles to provide sufficient diversity gain and error rate performance guarantees under time-varying or high-Doppler channels. Furthermore, while some improved schemes enhance performance by introducing multiple antennas and multi-symbol joint detection, they significantly increase receiver complexity and power consumption, contradicting the design principles of "low cost, low power consumption, and lightweight" for IoT terminals. Summary of the Invention

[0004] In view of the above problems, embodiments of the present invention are proposed to provide an orthogonal frequency division multiplexing communication method, apparatus and device based on two-dimensional index modulation that overcomes or at least partially solves the above problems.

[0005] In a first aspect, embodiments of the present invention provide an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, applied at a transmitting end, the method comprising: Obtain the bitstream; Generate an orthogonal frequency division multiplexing (OFDM) baseband signal; the OFDM baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset is used to indicate the position of the pilot subcarrier, the pilot modulation subset is used to generate pilot modulation symbols, and the pilot index bits are determined based on the bit stream; The orthogonal frequency division multiplexing (OFDM) baseband signal is sent to the receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal.

[0006] Optionally, generating the orthogonal frequency division multiplexing baseband signal includes: The bit stream is divided into pilot index bits and active subcarrier index bits; The pilot index bits are divided into a position selection subset and a pilot modulation subset; Based on the location selection subset indicated by the location, the corresponding subcarrier is selected from the preset subcarrier set as the pilot subcarrier; The pilot modulation subset is mapped to pilot modulation symbols and loaded onto the pilot subcarrier; In the subcarrier set excluding the pilot subcarrier, a corresponding subcarrier is selected as the active data subcarrier according to the active subcarrier index bit, and data modulation symbols are loaded on the active data subcarrier. The subcarriers in the subcarrier set, excluding the pilot subcarriers and the active data subcarriers, are set to zero to obtain the frequency domain signal vector; Based on the frequency domain signal vector, an orthogonal frequency division multiplexing baseband signal is generated.

[0007] Optionally, the step of selecting a corresponding subcarrier as an active data subcarrier from the subcarrier set excluding the pilot subcarrier, based on the active subcarrier index bit, and loading data modulation symbols on the active data subcarrier, includes: The active subcarrier index bits are divided into an active position subset and a modulation subset. The active position subset is used to indicate the position of the active data subcarrier, and the modulation subset is used to generate data modulation symbols. In the subcarrier set excluding the pilot subcarrier, the corresponding subcarrier is selected as the active data subcarrier according to the active data subcarrier position indicated by the active position subset; The modulation subset is mapped to data modulation symbols and loaded into the active data subcarrier.

[0008] Optionally, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the position selection subset is used to indicate the position of the pilot subcarrier in each sub-block; the step of selecting a portion of the corresponding subcarriers from a preset subcarrier set as pilot subcarriers based on the pilot subcarrier positions indicated by the position selection subset includes: Within each sub-block, the pilot subcarrier position indicated by the selected subset is chosen according to the position, and the corresponding subcarrier is selected as the pilot subcarrier.

[0009] Optionally, the pilot modulation symbol is a BPSK modulation symbol.

[0010] Optionally, generating the orthogonal frequency division multiplexing baseband signal based on the frequency domain signal vector includes: Perform an inverse fast Fourier transform on the frequency domain signal vector to obtain a time-domain orthogonal frequency division multiplexing symbol; A cyclic prefix is ​​configured before the time-domain orthogonal frequency division multiplexing symbol to form the orthogonal frequency division multiplexing baseband signal.

[0011] Secondly, embodiments of the present invention provide an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, applied at a receiving end, the method comprising: Receives orthogonal frequency division multiplexing baseband signals; Based on the orthogonal frequency division multiplexing baseband signal, the bit stream is recovered; the orthogonal frequency division multiplexing baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset corresponds to the position of the pilot subcarrier in the orthogonal frequency division multiplexing baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

[0012] Optionally, recovering the bit stream based on the orthogonal frequency division multiplexing baseband signal includes: The orthogonal frequency division multiplexing baseband signal is synchronized and subjected to fast Fourier transform to obtain the frequency domain received signal; Based on the frequency domain received signal, the position of the pilot subcarrier is detected and the pilot modulation symbol is demodulated to recover the pilot index bit; In the preset subcarrier set excluding the pilot subcarrier, the position of the active data subcarrier is identified and the data modulation symbol is demodulated to recover the active subcarrier index bit; The pilot index bits and the active subcarrier index bits are combined to restore the bit stream.

[0013] Optionally, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the step of detecting the position of the pilot subcarriers and demodulating the pilot modulation symbols based on the frequency domain received signal to recover the pilot index bits includes: Based on the frequency domain received signal, calculate the log-likelihood ratio of each subcarrier; Select the subcarrier with the largest log-likelihood ratio from each sub-block as the pilot candidate position; Based on the frequency domain received value at the pilot candidate position, the pilot modulation symbol is demodulated according to the first preset modulation mapping relationship, and the pilot modulation symbol is mapped to the corresponding pilot modulation subset; The pilot candidate positions are converted into a position selection subset, the position selection subset is merged with the pilot modulation subset, and the pilot index bits are recovered.

[0014] Optionally, identifying the position of the active data subcarrier and demodulating the data modulation symbols in the subcarriers other than the pilot subcarriers in the preset subcarrier set to recover the active subcarrier index bit includes: Based on the frequency domain received signal, the log-likelihood ratio of each subcarrier is calculated on the subcarrier set excluding the pilot subcarrier; Select the position of the subcarrier with the largest log-likelihood ratio from each sub-block as the activation candidate position; Based on the frequency domain received value at the activated candidate position, the data modulation symbol is demodulated according to the second preset modulation mapping relationship, and the data modulation symbol is mapped to the corresponding modulation subset; The activation candidate positions are converted into an activation position subset, the activation position subset is merged with the modulation subset, and the activation subcarrier index bits are recovered.

[0015] Thirdly, embodiments of the present invention provide an orthogonal frequency division multiplexing communication device based on two-dimensional index modulation, applied at a transmitting end, the device comprising: Bit stream acquisition module, used to acquire bit streams; An orthogonal frequency division multiplexing (OFDM) baseband signal generation module is used to generate an OFDM baseband signal; the OFDM baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset is used to indicate the position of the pilot subcarrier, the pilot modulation subset is used to generate pilot modulation symbols, and the pilot index bits are determined based on the bit stream; An orthogonal frequency division multiplexing (OFDM) baseband signal transmission module is used to transmit the OFDM baseband signal to a receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal.

[0016] Optionally, the orthogonal frequency division multiplexing baseband signal generation module includes: The first partitioning submodule is used to divide the bit stream into the pilot index bits and the active subcarrier index bits; The second partitioning submodule is used to partition the pilot index bits into a position selection subset and a pilot modulation subset; The pilot subcarrier determination submodule is used to select the pilot subcarrier position indicated by the position selection subset according to the position selection subset, and select the corresponding subcarrier as the pilot subcarrier from the preset subcarrier set; A pilot modulation symbol loading submodule is used to map the pilot modulation subset to pilot modulation symbols and load them onto the pilot subcarrier; The active data subcarrier determination submodule is used to select a corresponding subcarrier as an active data subcarrier from the subcarrier set other than the pilot subcarrier, according to the active subcarrier index bit, and load data modulation symbols on the active data subcarrier; The frequency domain signal vector determination submodule is used to set all subcarriers in the subcarrier set except for the pilot subcarriers and the active data subcarriers to zero, thereby obtaining the frequency domain signal vector; The orthogonal frequency division multiplexing baseband signal generation submodule is used to generate an orthogonal frequency division multiplexing baseband signal based on the frequency domain signal vector.

[0017] Optionally, the activated data subcarrier determination submodule includes: A partitioning unit is used to divide the active subcarrier index bits into an active position subset and a modulation subset, wherein the active position subset is used to indicate the position of the active data subcarrier, and the modulation subset is used to generate data modulation symbols; An active data subcarrier determination unit is used to select a corresponding subcarrier as an active data subcarrier from the subcarrier set other than the pilot subcarrier, according to the active data subcarrier position indicated by the active position subset; A data modulation symbol loading unit is used to map the modulation subset into data modulation symbols and load them onto the active data subcarrier.

[0018] Optionally, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the position selection subset is used to indicate the position of the pilot subcarriers in each sub-block; the pilot subcarrier determination submodule includes: The pilot subcarrier determination unit is used to select the pilot subcarrier position indicated by the subset according to the position in each subblock, and select the corresponding subcarrier as the pilot subcarrier.

[0019] Optionally, the pilot modulation symbol is a BPSK modulation symbol.

[0020] Optionally, the orthogonal frequency division multiplexing baseband signal generation submodule includes: The time-domain orthogonal frequency division multiplexing symbol determination unit is used to perform an inverse fast Fourier transform on the frequency domain signal vector to obtain time-domain orthogonal frequency division multiplexing symbols; An orthogonal frequency division multiplexing (OFDM) baseband signal determination unit is used to configure a cyclic prefix before the time-domain OFDM symbol to form the OFDM baseband signal.

[0021] Fourthly, embodiments of the present invention provide an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, applied at a receiving end, the apparatus comprising: Orthogonal Frequency Division Multiplexing (OFDM) baseband signal receiving module, used to receive OFDM baseband signals; A bitstream recovery module is used to recover a bitstream based on the orthogonal frequency division multiplexing (OFDM) baseband signal. The OFDM baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset corresponds to the position of the pilot subcarrier in the OFDM baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

[0022] Optionally, the bitstream recovery module includes: The frequency domain received signal determination submodule is used to perform synchronization and fast Fourier transform on the orthogonal frequency division multiplexing baseband signal to obtain the frequency domain received signal; The pilot index bit recovery submodule is used to detect the position of the pilot subcarrier and demodulate the pilot modulation symbol based on the frequency domain received signal in order to recover the pilot index bit. The active subcarrier index bit recovery submodule is used to identify the position of the active data subcarrier and demodulate the data modulation symbol in the subcarriers other than the pilot subcarrier in the preset subcarrier set in order to recover the active subcarrier index bit. The bitstream recovery submodule is used to merge the pilot index bits and the active subcarrier index bits to recover the bitstream.

[0023] Optionally, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the pilot index bit recovery submodule includes: The first log-likelihood ratio calculation unit is used to calculate the log-likelihood ratio of each subcarrier based on the frequency domain received signal. The pilot candidate location determination unit is used to select the subcarrier with the largest log-likelihood ratio from each sub-block as the pilot candidate location; The pilot modulation subset determination unit is used to demodulate the pilot modulation symbols according to the frequency domain received values ​​at the pilot candidate positions and according to a first preset modulation mapping relationship, and map the pilot modulation symbols to the corresponding pilot modulation subsets. The pilot index bit determination unit is used to convert the pilot candidate positions into a position selection subset, merge the position selection subset with the pilot modulation subset, and recover the pilot index bits.

[0024] Optionally, activating the subcarrier index bit recovery submodule includes: The second log-likelihood ratio calculation unit is used to calculate the log-likelihood ratio of each subcarrier in the subcarrier set, excluding the pilot subcarrier, based on the frequency domain received signal. The activation candidate position determination unit is used to select the position of the subcarrier with the largest log-likelihood ratio from each sub-block as the activation candidate position; The modulation subset determination unit is used to demodulate the data modulation symbols according to the frequency domain received values ​​at the activation candidate positions and according to the second preset modulation mapping relationship, and map the data modulation symbols to the corresponding modulation subsets; An activation subcarrier index bit recovery unit is used to convert the activation candidate position into an activation position subset, merge the activation position subset with the modulation subset, and recover the activation subcarrier index bit.

[0025] Fifthly, embodiments of the present invention provide an electronic device including a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the steps of the method described in the first aspect.

[0026] In a sixth aspect, embodiments of the present invention provide a readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect.

[0027] This invention provides an orthogonal frequency division multiplexing (OFDM) communication based on two-dimensional index modulation, applied at the transmitting end. First, a bit stream is acquired; then, an OFDM baseband signal is generated. This baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset indicates the position of the pilot subcarriers, and the pilot modulation subset generates pilot modulation symbols. The pilot index bits are determined based on the bit stream. The OFDM baseband signal is then transmitted to the receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal. This invention's two-dimensional index modulation OFDM baseband signal indexes pilot position communication information and simultaneously loads pilot modulation symbols to achieve pilot information multiplexing. By using the pilot subcarrier position as the information dimension in index modulation, the transmission dimension is expanded without adding additional subcarriers, thereby effectively improving spectrum resource utilization. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the steps of an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation according to an embodiment of the present invention. Figure 2 This is a schematic diagram of an orthogonal frequency division multiplexing baseband signal generation based on two-dimensional index modulation according to an embodiment of the present invention; Figure 3 This is a schematic diagram of frequency domain communication information of orthogonal frequency division multiplexing baseband signals based on two-dimensional index modulation, according to an embodiment of the present invention. Figure 4 This is a flowchart of another orthogonal frequency division multiplexing communication method based on two-dimensional index modulation according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a communication signal processing procedure according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of an orthogonal frequency division multiplexing communication device based on two-dimensional index modulation according to an embodiment of the present invention; Figure 7 This is a schematic diagram of another orthogonal frequency division multiplexing communication device based on two-dimensional index modulation according to an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] With the rapid development of the Internet of Things (IoT), the massive number of low-power terminal devices has placed comprehensive demands on wireless communication systems, requiring high connection density, low power consumption, and high reliability. Orthogonal Frequency Division Multiplexing (OFDM) technology, due to its excellent resistance to multipath fading and ease of implementation, has been widely used in mainstream communication standards such as 4G LTE, 5G NR, and Wi-Fi. However, traditional OFDM requires activating all subcarriers for data or pilot transmission in each symbol period, resulting in limited spectrum resource utilization efficiency and fixed pilot overhead, making it difficult to meet the stringent energy efficiency and spectrum efficiency requirements of IoT scenarios.

[0031] To improve spectral efficiency, researchers have proposed OFDM with Index Modulation (OFDM-IM) technology. This technology increases transmission rates without increasing bandwidth by activating only a subset of subcarriers and encoding the "activation mode" as an additional information dimension. However, existing OFDM-IM schemes still have significant limitations: firstly, pilot subcarriers typically use fixed positions and known values, serving only for channel estimation and not participating in information carrying, resulting in a waste of valuable frequency domain resources; secondly, its index modulation only applies to the activation state of data subcarriers, constituting single-dimensional modulation, which struggles to provide sufficient diversity gain and error rate performance guarantees under time-varying or high-Doppler channels. Furthermore, while some improved schemes enhance performance by introducing multiple antennas and multi-symbol joint detection, they significantly increase receiver complexity and power consumption, contradicting the design principles of "low cost, low power consumption, and lightweight" for IoT terminals.

[0032] One of the core concepts of this invention is the orthogonal frequency division multiplexing baseband signal with dual-dimensional index modulation, which indexes the pilot position to communicate information and loads pilot modulation symbols to achieve pilot information multiplexing. By using the pilot subcarrier position as the information dimension to participate in index modulation, the transmission dimension is expanded without adding extra subcarriers, thereby effectively improving the utilization rate of spectrum resources.

[0033] Reference Figure 1 The diagram illustrates a flowchart of an orthogonal frequency division multiplexing communication method based on two-dimensional index modulation according to an embodiment of the present invention, which may specifically include the following steps: Step 101: Obtain the bit stream.

[0034] Step 102: Generate an orthogonal frequency division multiplexing (OFDM) baseband signal. The OFDM baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset is used to indicate the position of the pilot subcarrier, and the pilot modulation subset is used to generate pilot modulation symbols. The pilot index bits are determined based on the bit stream.

[0035] Step 103: Send an orthogonal frequency division multiplexing baseband signal to the receiving end so that the receiving end can recover the bit stream based on the orthogonal frequency division multiplexing baseband signal.

[0036] The transmitting end acquires the bit stream to be transmitted, then generates a two-dimensional indexed modulated orthogonal frequency division multiplexing baseband signal based on the bit stream to be transmitted, and sends the orthogonal frequency division multiplexing baseband signal to the receiving end so that the receiving end can recover the bit stream based on the orthogonal frequency division multiplexing baseband signal.

[0037] The dual-indexed modulated orthogonal frequency division multiplexing (OFDM) baseband signal generated at the transmitting end achieves dual-dimensional transmission of communication information in the frequency domain by introducing pilot indexing technology. Specifically, one dimension is used for subcarrier index modulation, while the other dimension utilizes the activation state of pilot subcarrier positions for indexing. This effectively improves spectrum utilization efficiency and channel estimation accuracy without significantly increasing system complexity. The waveform of the dual-indexed modulated OFDM baseband signal achieves embedded transmission of communication information by loading random pilot subcarrier position information onto silent subcarriers and modulating pilot modulation symbols at the pilot positions. This structure ensures that the pilot signal is used for channel estimation while enabling the pilot to undertake part of the information transmission function, thereby improving the spectrum efficiency of system resources. Because dual-indexed modulated OFDM introduces an indexing mechanism at the pilot level, it can further improve the robustness and anti-interference capability of the system while maintaining the performance of traditional channel estimation.

[0038] In this embodiment of the invention, the pilot modulation symbol is the BPSK modulation symbol.

[0039] The pilot modulation symbols are generated using binary phase shift keying (BPSK) modulation. For example, the transmitting end maps a pilot modulation subset (e.g., 1 bit of information) in the pilot index bit to a BPSK symbol: when the pilot modulation subset is "0", it is mapped to +1; when the pilot modulation subset is "1", it is mapped to... 1 (or conversely), the BPSK symbol is loaded onto the pilot subcarrier position indicated by the position selection subset and participates in the construction of the orthogonal frequency division multiplexing signal. BPSK modulation symbols have strong noise immunity and can reliably demodulate even in low signal-to-noise ratio environments, thus improving the robustness of pilot transmission. Furthermore, its constellation points contain only two real symbols (±1), simplifying the demodulation decision logic at the receiver and significantly reducing the demodulation complexity. For battery-powered terminal devices (such as IoT sensors, wearable devices, and industrial wireless nodes), this feature can effectively reduce the power consumption of the receiver link and extend the device's battery life, making it particularly suitable for power-sensitive low-power communication scenarios.

[0040] In this embodiment of the invention, step 102 may specifically include the following sub-steps: Sub-step S11 divides the bit stream into pilot index bits and active subcarrier index bits.

[0041] Sub-step S12 divides the pilot index bits into a position selection subset and a pilot modulation subset.

[0042] Sub-step S13: Select the pilot subcarrier position indicated by the location selection subset, and select the corresponding subcarrier from the preset subcarrier set as the pilot subcarrier.

[0043] Sub-step S14: Map the pilot modulation subset to pilot modulation symbols and load them onto the pilot subcarrier.

[0044] Sub-step S15: In the subcarrier set excluding the pilot subcarrier, select the corresponding subcarrier as the active data subcarrier according to the active subcarrier index bit, and load data modulation symbols on the active data subcarrier.

[0045] Sub-step S16 involves setting all subcarriers in the subcarrier set except for pilot subcarriers and active data subcarriers to zero, thus obtaining the frequency domain signal vector.

[0046] Sub-step S17: Generate an orthogonal frequency division multiplexing baseband signal based on the frequency domain signal vector.

[0047] The input bitstream to be transmitted is divided into two parts: pilot index bits and active subcarrier index bits. The pilot index bits carry pilot-related position and modulation information, while the active subcarrier index bits indicate the activation state and modulation content of the data subcarriers. The pilot index bits are further divided into two subsets: a position selection subset and a pilot modulation subset. The position selection subset determines the specific position of the pilot subcarriers in the frequency domain, and the pilot modulation subset generates the corresponding pilot modulation symbols. Based on the index information indicated by the position selection subset, data is transmitted from a preset set of subcarriers (e.g., a total of N subcarriers). In an orthogonal frequency division multiplexing (OFDM) signal system, several subcarriers are selected as pilot subcarriers; the pilot modulation subset is mapped to pilot modulation symbols according to a preset modulation mapping relationship (e.g., BPSK mapping), and the symbols are loaded onto the selected pilot subcarrier positions; among the remaining subcarriers after excluding the selected pilot subcarriers, some subcarriers are selected as active data subcarriers according to the active subcarrier index bits, and data modulation symbols obtained by mapping the active modulation subset are loaded onto them; all other subcarriers in the subcarrier set except for the pilot subcarriers and active data subcarriers are set to zero, thereby constructing a sparse frequency domain signal vector, in which non-zero elements only appear at the pilot or active data positions. Based on the frequency domain signal vector, an OFDM baseband signal is generated and transmitted to the receiving end via the radio frequency front end.

[0048] Reference Figure 2 Pilot indexing and BPSK constellation modulation are applied to subcarriers within any symbol period. The number of pilots per symbol is denoted as (Np). Na subcarriers are activated as frequency domain index bits on the remaining N - Np empty subcarriers and constellation point modulation is performed. The remaining silent subcarriers are set to zero. Based on this modulation method, a two-dimensional indexed modulated orthogonal frequency division multiplexing baseband signal is obtained.

[0049] The embodiments of the present invention utilize pilot subcarrier positions and active data subcarrier positions to simultaneously carry information bits (i.e., "dual-index modulation"), which transmits additional position index information without increasing bandwidth and transmission power, effectively improving the spectral efficiency of the system.

[0050] In this embodiment of the invention, sub-step S15 may specifically include the following sub-steps: Sub-step S151 divides the active subcarrier index bits into an active position subset and a modulation subset. The active position subset is used to indicate the position of the active data subcarrier, and the modulation subset is used to generate data modulation symbols.

[0051] Sub-step S152: In the subcarrier set excluding the pilot subcarrier, select the corresponding subcarrier as the active data subcarrier according to the active data subcarrier position indicated by the active position subset.

[0052] Sub-step S153: Map the modulation subset to data modulation symbols and load them onto the active data subcarrier.

[0053] The active subcarrier index bits are divided into two logical subsets: an active position subset and a modulation subset. The active position subset indicates the data subcarrier positions that should be activated within the available subcarrier range; the modulation subset generates corresponding data modulation symbols to carry additional information bits. From a preset set of subcarriers, after excluding positions already selected as pilot subcarriers, several subcarriers are selected as active data subcarriers based on the index information indicated by the active position subset. The modulation subset is converted into corresponding data modulation symbols according to a preset higher-order modulation mapping relationship, and these symbols are loaded onto the selected active data subcarriers. The remaining unselected subcarriers retain a value of zero. By subdividing the active subcarrier index bits into an active position subset and a modulation subset, and using them to control the subcarrier positions and modulation symbols respectively, two-dimensional information encoding on the data side is achieved, thereby significantly improving the effective information transmission rate within a limited bandwidth.

[0054] In this embodiment of the invention, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; a position selection subset is used to indicate the position of the pilot subcarriers in each sub-block; based on the pilot subcarrier positions indicated by the position selection subset, a portion of the corresponding subcarriers are selected as pilot subcarriers from a preset subcarrier set, including: Within each sub-block, the pilot subcarrier position indicated by the location selection subset is selected, and the corresponding subcarrier is selected as the pilot subcarrier.

[0055] Reference Figure 3The vertical axis represents the frequency domain, indicating the subcarrier numbers (#1 to #N), with a total of N subcarriers. The horizontal axis represents the time / symbol period, from left to right, representing multiple consecutive orthogonal frequency division multiplexing symbols (or multiple sub-blocks within a symbol), with a total length of MT, where T is the time width of a single sub-block and M is the number of sub-blocks (i.e., the number of symbols transmitted in parallel). Figure 3 The display shows the frequency domain structure over multiple time slots (or sub-blocks). Each column represents an orthogonal frequency division multiplexing symbol or a frequency domain signal in a sub-block. There are a total of M sub-blocks, and each sub-block contains N subcarriers, corresponding to positions in the frequency domain.

[0056] A sparse structure is adopted in the frequency domain, where each sub-block contains multiple subcarriers, and some subcarriers are configured as pilot subcarriers. Figure 3 The “Pilot” in the text refers to the fact that only a portion of the remaining subcarriers are activated to carry data modulation symbols. Figure 3 In the pilot signal, “a_{i,j}” is used, while the remaining subcarriers are set to zero. By dynamically selecting the pilot position and the active data position, two-dimensional indexed modulation is achieved, effectively improving spectrum utilization and system robustness.

[0057] In this embodiment of the invention, the preset subcarrier set is divided into several non-overlapping sub-blocks. Each sub-block contains a fixed number of subcarriers. The sub-blocks can be distributed in the frequency domain, which can avoid all pilots or data from being concentrated in the deep fading region. Even if a sub-block is interfered with, other sub-blocks can still work normally, improving link robustness. Furthermore, traditional index modulation requires searching all possible activation combinations in the entire frequency band, and the complexity increases exponentially with the number of subcarriers. By dividing the sub-blocks, the global search problem can be decomposed into multiple independent local search problems, significantly reducing the detection complexity at the receiver.

[0058] In another implementation, multimode indexed modulation requires converting a single symbol... The bit is divided into three parts: variable-scale index bit. Activate subcarrier index bits Pilot index bits .Will Bits are divided into and Two parts, utilizing Use the remaining bits to select the pilot bits. The bits are modulated to the pilot positions using BPSK. After pilot index modulation is completed, the remaining empty subcarriers are rearranged. The subcarrier index is activated by using the bit-bit chirp field. Finally, using... The SIDFnT transform of bit-bit variable-scale indexing yields the orthogonal frequency division multiplexing baseband signal with two-dimensional index modulation.

[0059] The pilot index modulation implementation process is similar to that of chirp domain activated subcarrier indexing, which will... The subcarriers are evenly distributed as follows: Each pilot sub-block contains [number] pilot sub-blocks. Each carrier selects each pilot subblock. There are 10 subcarriers used as pilot bits, totaling 1000. Options, can be loaded bits, satisfying The number of pilot subcarriers is .

[0060] No. Each block Each bit can be used to select the activation index bit from the available indexes using a lookup table method, thus activating the sub-block pilot index. Arranged in ascending order

[0061] in, , , Indicates the first The first sub-block For each subcarrier loaded with pilot information, the pilot activation index is... satisfy

[0062] After loading BPSK modulation information at the pilot positions, the empty subcarriers outside the pilot index positions are rearranged, and the rearranged subcarriers are... The empty subcarrier index in each symbol Sort in ascending order, which can be represented as

[0063] in, .based on Perform chirp field activation subcarrier index, activate subcarrier index satisfy

[0064] After zeroing the silent subcarriers, the frequency domain communication information of the two-dimensional indexed modulated orthogonal frequency division multiplexing baseband signal is as follows: Figure 3 As shown, the modulation information of any symbol is related to the indexing method in multiple modes.

[0065] In this embodiment of the invention, sub-step S17 may include the following sub-steps: Sub-step S171: Perform inverse fast Fourier transform on the frequency domain signal vector to obtain time-domain orthogonal frequency division multiplexing symbols.

[0066] Sub-step S172: Configure a cyclic prefix before the time-domain orthogonal frequency division multiplexing symbol to obtain the orthogonal frequency division multiplexing baseband signal.

[0067] After completing pilot index modulation and active subcarrier index modulation, the transmitter obtains a frequency-domain communication information symbol vector X of length N. Non-zero elements appear only on the pilot subcarriers and active data subcarriers indicated by the position selection subset and active position subset, while the remaining subcarriers are set to zero. Subsequently, an Nth-order Inverse Fast Fourier Transform (IFFT) is performed on this frequency-domain symbol vector X to convert it into the corresponding time-domain orthogonal frequency division multiplexing (OFDM) symbol x. This transformation utilizes the orthogonality principle of OFDM to efficiently synthesize the modulation symbols on multiple subcarriers into a single time-domain waveform. Next, the parallel time-domain samples output by the IFFT are converted from parallel to serial to form a serial baseband data stream, and a cyclic prefix (CP) is added to its front end, ultimately generating a two-dimensional index-modulated OFDM baseband signal. By introducing a two-dimensional index modulation mechanism into the orthogonal frequency division multiplexing system, and combining it with sub-block structure, BPSK pilot design and sparse frequency domain signal construction, the spectral efficiency and transmission reliability are significantly improved. At the same time, the inverse fast Fourier transform and time-domain baseband shaping process adopted are fully compatible with the existing orthogonal frequency division multiplexing standard architecture. While ensuring high spectrum utilization, it effectively reduces the implementation complexity and power consumption of the transceiver, making it suitable for low-power communication scenarios.

[0068] For example, by performing an Nth-order IFFT transform on the frequency domain communication information symbols of the orthogonal frequency division multiplexing (OFDM) signal with dual-index modulation, and then performing parallel-to-serial conversion to complete pilot index modulation and active subcarrier index modulation, the communication information of the OFDM baseband signal with dual-index modulation in the frequency domain can be obtained. Baseband signal Represented as

[0069] Orthogonal frequency division multiplexing of dual-dimensional index modulation realizes dual-dimensional index modulation, achieving multi-dimensional improvement in communication spectrum efficiency.

[0070] The dual-dimensional indexed modulation orthogonal frequency division multiplexing baseband signal of this invention indexes communication information in the pilot position and simultaneously loads BPSK modulation data to achieve pilot information multiplexing. The pilot position is used as an information dimension to participate in indexed modulation, expanding the transmission dimension without adding extra subcarriers, effectively improving spectrum resource utilization, and achieving synergistic optimization of communication overhead and channel estimation. The dual-mode indexed modulation mechanism performs index mapping in both the frequency domain and the pilot domain to form a multi-dimensional information carrying structure. Through joint index mapping, the diversity gain of the signal in multipath fading environments is enhanced, improving the system's anti-interference and error correction capabilities, significantly reducing the bit error rate, and improving the stability and reliability of the system under complex channel conditions.

[0071] Reference Figure 4 This diagram illustrates a flowchart of another orthogonal frequency division multiplexing communication method based on two-dimensional index modulation according to an embodiment of the present invention, applied at the receiving end, and specifically includes the following steps: Step 201: Receive the orthogonal frequency division multiplexing baseband signal.

[0072] Step 202: Recover the bit stream based on the orthogonal frequency division multiplexing baseband signal; the orthogonal frequency division multiplexing baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset corresponds to the position of the pilot subcarrier in the orthogonal frequency division multiplexing baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

[0073] The receiver first receives an orthogonal frequency division multiplexing (OFDM) baseband signal transmitted via a wireless channel. This signal is generated by the transmitter through two-dimensional index modulation, and its frequency domain structure exhibits sparse characteristics, containing dynamically configured pilot subcarriers and active data subcarriers. Then, based on the OFDM baseband signal, the original input bitstream is recovered. By recovering the pilot index bits, which include a position selection subset and a pilot modulation subset, from the OFDM baseband signal at the receiver, both the position of the pilot subcarriers and the modulation symbols are used to carry information. This not only improves spectral efficiency but also enables the receiver to accurately recover the pilot index bits by analyzing both the pilot position and symbol dimensions, enhancing the reliability and robustness of index demodulation.

[0074] In this embodiment of the invention, step 202 may include the following sub-steps: Sub-step S21 involves synchronizing and performing a fast Fourier transform on the orthogonal frequency division multiplexing baseband signal to obtain the frequency domain received signal.

[0075] Sub-step S22 involves detecting the position of the pilot subcarrier and demodulating the pilot modulation symbols based on the frequency domain received signal to recover the pilot index bits.

[0076] Sub-step S23: In the preset subcarrier set, excluding pilot subcarriers, identify the position of the active data subcarrier and demodulate the data modulation symbols to recover the active subcarrier index bit.

[0077] Sub-step S24: Merge pilot index bits and active subcarrier index bits to restore the bit stream.

[0078] Reference Figure 5 After receiving the orthogonal frequency division multiplexed signal modulated by RF dual-dimensional index modulation, the receiver first converts it to the baseband range through down-conversion. Then, a synchronization module completes symbol timing and carrier synchronization to obtain a stable baseband signal. An N-point FFT transform is performed on the baseband signal to obtain frequency domain communication data (frequency domain received signal). Then, based on this frequency domain received signal, the position of the pilot subcarrier is detected and the pilot modulation symbols carried on it are demodulated to recover the pilot index bits. Simultaneously, among the remaining subcarriers after excluding the pilot subcarriers, the position of the active data subcarrier is further identified and the corresponding data modulation symbols are demodulated to recover the active subcarrier index bits. Finally, the recovered pilot index bits and active subcarrier index bits are merged to completely reconstruct the original input bitstream. By recovering the pilot index bits and active subcarrier index bits from the frequency domain received signal at the receiver and merging them to reconstruct the original bitstream, complete parsing of dual-dimensional index modulation information is achieved.

[0079] In this embodiment of the invention, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; sub-step S22 may specifically include the following sub-steps: Sub-step S221: Calculate the log-likelihood ratio of each subcarrier based on the received signal in the frequency domain.

[0080] Sub-step S222: Select the subcarrier with the largest log-likelihood ratio from each sub-block as the pilot candidate position.

[0081] Sub-step S223: Based on the frequency domain received value at the pilot candidate position, demodulate the pilot modulation symbol according to the first preset modulation mapping relationship, and map the pilot modulation symbol to the corresponding pilot modulation subset.

[0082] Sub-step S224: Convert the pilot candidate positions into a position selection subset, merge the position selection subset with the pilot modulation subset, and restore the pilot index bits.

[0083] Based on the received signal in the frequency domain, the log-likelihood ratio (LLR) of each subcarrier is calculated to measure the probability that each subcarrier carries a pilot signal. Within each sub-block, the subcarrier with the largest LLR is selected as the pilot candidate position for that sub-block. According to the received frequency value at the pilot candidate position, the pilot modulation symbol is demodulated according to a first preset modulation mapping relationship, and the symbol is mapped to the corresponding pilot modulation subset. The selected pilot candidate positions in each sub-block are converted into position selection subsets and merged with the pilot modulation subsets to recover the complete pilot index bits. By dividing the subcarrier set into multiple sub-blocks and independently selecting pilot candidate positions based on the LLR within each sub-block, the high-complexity operation of globally searching all subcarrier combinations is avoided. At the same time, pilot position detection and symbol demodulation are decoupled into two sequential steps, allowing the pilot index bits to be efficiently recovered through local optimal decision-making. This method significantly reduces the computational complexity and processing latency of the receiver while ensuring detection performance, which is beneficial for achieving low-power, real-time demodulation of two-dimensional index information in resource-constrained terminals.

[0084] For example, the pilot position is first determined using a two-stage log-likelihood ratio (LLR) decision algorithm. First, the LLR decision unit determines the pilot position, and the pilot value is used to determine the decision reference symbol for the algorithm. By determining whether the subcarrier information in the frequency domain is a pilot value, the logarithmic result of the posterior probability ratio of the communication information can be provided. Let... Let be the pilot constellation modulation order, the th The posterior probability expression for the communication information of each symbol is:

[0085] The communication information loaded at the pilot positions in this paper is BPSK modulated data, which satisfies... .when The larger the value, the greater the probability that the current location will be identified as a pilot location by the pilot index selector. This is achieved using Bayes' theorem. and The system chirp domain noise variance is... The formula can be reformulated as

[0086] Calculate After determining the LLR value, the result is divided into pilot blocks, and the first segment of each sub-block is determined. The maximum value is the pilot index position. The pilot index bit information is determined by judging the pilot index bit using the pilot index lookup table.

[0087] In this embodiment of the invention, sub-step S23 may specifically include the following sub-steps: Sub-step S231: Based on the frequency domain received signal, calculate the log-likelihood ratio of each subcarrier in the subcarrier set excluding the pilot subcarrier; Sub-step S232: Select the position of the subcarrier with the largest log-likelihood ratio from each sub-block as the activation candidate position; Sub-step S233: Based on the frequency domain received value at the activation candidate position, demodulate the data modulation symbol according to the second preset modulation mapping relationship, and map the data modulation symbol to the corresponding modulation subset; Sub-step S234: Convert the active candidate positions into an active position subset, merge the active position subset with the modulation subset, and restore the active subcarrier index bits.

[0088] Based on the received signal in the frequency domain, the components corresponding to the detected pilot subcarriers are first removed or zeroed out to eliminate interference from the pilots on the detection of data subcarriers, resulting in a processed frequency domain signal containing only potentially active data subcarriers and noise. Subsequently, for the remaining subcarriers in the subcarrier set excluding the pilot subcarriers, the log-likelihood ratio (LLR) of each subcarrier is calculated to characterize its probability of being activated as a data subcarrier. Within each subblock, the position of the subcarrier with the largest LLR from the remaining subcarriers is selected as the activation candidate position for that subblock. Based on the frequency domain received value at the active candidate position, constellation point decision is made according to the second preset modulation mapping relationship (e.g., M-QAM constellation mapping), the corresponding data modulation symbol is demodulated, and the symbol is mapped to the corresponding modulation subset; the active candidate positions determined in each sub-block are converted into active position subsets and merged with the modulation subsets, thereby restoring the complete active subcarrier index bits. This not only ensures the demodulation performance of data side information in two-dimensional index modulation, but also significantly reduces the algorithm complexity through a step-by-step decision mechanism, making it suitable for low-power communication scenarios under high-order modulation.

[0089] For example, activation subcarrier index demodulation also requires determining the location of the activation subcarrier and performing... -QAM constellation demodulation. Before performing active subcarrier index demodulation, it is necessary to... 3D communication information matrix Perform pilot removal processing to obtain The activation index communication matrix B of dimension B has the following transformation relationship:

[0090] This invention presents a lightweight two-stage LLR decision algorithm that achieves low-complexity signal demodulation and information recovery. It reduces computational complexity while preserving index modulation gain, avoids the exponential search and high-power operation of traditional schemes, and achieves a balance between performance and complexity, meeting the low-power and lightweight requirements of IoT terminals.

[0091] Referring to Table 1 below, the spectral efficiencies of the Two-Dimensional Indexed Modulation Orthogonal Frequency Division Multiplexing (DIM-OFDM) system and the Indexed Modulation Orthogonal Frequency Division Multiplexing (OFDM-IM) system are shown. The highest spectral efficiency for each number of sub-blocks is plotted in the table. As can be seen from the table, the DIM-OFDM system improves the overall spectral efficiency by more than 55% compared to the traditional indexed modulation orthogonal frequency division multiplexing system. The DIM-OFDM system achieves the most significant spectral efficiency improvement when the number of sub-blocks per symbol is maximized. The highest spectral efficiency can be achieved for any system when the number of subcarriers per block is 1.

[0092]

[0093] Table 1 Reference Figure 6 The diagram illustrates a structural schematic of an orthogonal frequency division multiplexing communication device based on two-dimensional index modulation according to an embodiment of the present invention. Applied to the transmitting end, it may specifically include the following structure: Bit stream acquisition module 301 is used to acquire bit streams; The orthogonal frequency division multiplexing baseband signal generation module 302 is used to generate orthogonal frequency division multiplexing baseband signals. The orthogonal frequency division multiplexing baseband signals carry pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset is used to indicate the position of the pilot subcarrier, and the pilot modulation subset is used to generate pilot modulation symbols. The pilot index bits are determined based on the bit stream. The orthogonal frequency division multiplexing baseband signal transmission module 303 is used to transmit orthogonal frequency division multiplexing baseband signals to the receiving end so that the receiving end can recover the bit stream based on the orthogonal frequency division multiplexing baseband signals.

[0094] This invention provides an orthogonal frequency division multiplexing (OFDM) device based on two-dimensional index modulation, applied at the transmitting end. First, a bit stream is acquired; then, an OFDM baseband signal is generated. The OFDM baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset indicates the position of the pilot subcarrier, and the pilot modulation subset generates pilot modulation symbols. The pilot index bits are determined based on the bit stream. The OFDM baseband signal is then transmitted to the receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal. This invention's two-dimensional index modulation OFDM baseband signal indexes pilot position information and simultaneously loads pilot modulation symbols to achieve pilot information multiplexing. By using the pilot subcarrier position as the information dimension in index modulation, the transmission dimension is expanded without adding additional subcarriers, thereby effectively improving spectrum resource utilization.

[0095] In this embodiment of the invention, the orthogonal frequency division multiplexing baseband signal generation module includes: The first partitioning submodule is used to divide the bit stream into pilot index bits and active subcarrier index bits; The second partitioning submodule is used to partition the pilot index bits into a position selection subset and a pilot modulation subset; The pilot subcarrier determination submodule is used to select the pilot subcarrier position indicated by the position selection subset based on the position, and select the corresponding subcarrier from the preset subcarrier set as the pilot subcarrier; The pilot modulation symbol loading submodule is used to map a subset of pilot modulation to pilot modulation symbols and load them onto pilot subcarriers; The active data subcarrier determination submodule is used to select the corresponding subcarrier as the active data subcarrier from the subcarrier set excluding the pilot subcarrier, according to the active subcarrier index bit, and load data modulation symbols on the active data subcarrier. The frequency domain signal vector determination submodule is used to set all subcarriers in the subcarrier set except for pilot subcarriers and active data subcarriers to zero to obtain the frequency domain signal vector; The Orthogonal Frequency Division Multiplexing (OFDM) baseband signal generation submodule is used to generate OFDM baseband signals based on frequency domain signal vectors.

[0096] In this embodiment of the invention, activating the data subcarrier determination submodule includes: The partitioning unit is used to divide the active subcarrier index bits into an active position subset and a modulation subset. The active position subset is used to indicate the position of the active data subcarrier, and the modulation subset is used to generate data modulation symbols. The active data subcarrier determination unit is used to select the corresponding subcarrier as the active data subcarrier from the subcarrier set excluding the pilot subcarrier, according to the active data subcarrier position indicated by the active position subset; The data modulation symbol loading unit is used to map the modulation subset into data modulation symbols and load them onto the active data subcarrier.

[0097] In this embodiment of the invention, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; a position selection subset is used to indicate the position of the pilot subcarriers in each sub-block; the pilot subcarrier determination submodule includes: The pilot subcarrier determination unit is used to select the pilot subcarrier position indicated by the subset according to the position within each subblock, and select the corresponding subcarrier as the pilot subcarrier.

[0098] In this embodiment of the invention, the pilot modulation symbol is the BPSK modulation symbol.

[0099] In this embodiment of the invention, the orthogonal frequency division multiplexing baseband signal generation submodule includes: The time-domain orthogonal frequency division multiplexing symbol determination unit is used to perform inverse fast Fourier transform on the frequency domain signal vector to obtain the time-domain orthogonal frequency division multiplexing symbol; The orthogonal frequency division multiplexing baseband signal determination unit is used to configure a cyclic prefix before the time-domain orthogonal frequency division multiplexing symbol to form an orthogonal frequency division multiplexing baseband signal.

[0100] Reference Figure 7 This diagram illustrates another structural schematic of an orthogonal frequency division multiplexing communication device based on two-dimensional index modulation according to an embodiment of the present invention, which is applied to receiving and may specifically include the following structure: Orthogonal frequency division multiplexing baseband signal receiving module 401 is used to receive orthogonal frequency division multiplexing baseband signals; The bit stream recovery module 402 is used to recover the bit stream based on the orthogonal frequency division multiplexing baseband signal. The orthogonal frequency division multiplexing baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset corresponds to the position of the pilot subcarrier in the orthogonal frequency division multiplexing baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

[0101] In this embodiment of the invention, the bitstream recovery module includes: The frequency domain received signal determination submodule is used to perform synchronization and fast Fourier transform on the orthogonal frequency division multiplexing baseband signal to obtain the frequency domain received signal; The pilot index bit recovery submodule is used to detect the position of the pilot subcarrier and demodulate the pilot modulation symbols based on the received signal in the frequency domain in order to recover the pilot index bits. The active subcarrier index bit recovery submodule is used to identify the position of the active data subcarrier in the subcarriers other than the pilot subcarriers in the preset subcarrier set and demodulate the data modulation symbols to recover the active subcarrier index bit. The bitstream recovery submodule is used to merge pilot index bits and active subcarrier index bits to recover the bitstream.

[0102] In this embodiment of the invention, the subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the pilot index bit recovery submodule includes: The first log-likelihood ratio calculation unit is used to calculate the log-likelihood ratio of each subcarrier based on the received signal in the frequency domain. The pilot candidate location determination unit is used to select the subcarrier with the largest log-likelihood ratio from each sub-block as the pilot candidate location; The pilot modulation subset determination unit is used to demodulate the pilot modulation symbols according to the frequency domain received values ​​at the pilot candidate positions and according to the first preset modulation mapping relationship, and map the pilot modulation symbols to the corresponding pilot modulation subsets. The pilot index bit determination unit is used to convert pilot candidate positions into position selection subsets, merge the position selection subsets with the pilot modulation subsets, and recover the pilot index bits.

[0103] In this embodiment of the invention, activating the subcarrier index bit recovery submodule includes: The second log-likelihood ratio calculation unit is used to calculate the log-likelihood ratio of each subcarrier in the subcarrier set, excluding the pilot subcarrier, based on the received signal in the frequency domain. The activation candidate position determination unit is used to select the position of the subcarrier with the largest log-likelihood ratio from each sub-block as the activation candidate position; The modulation subset determination unit is used to demodulate the data modulation symbols according to the frequency domain received values ​​at the active candidate positions and according to the second preset modulation mapping relationship, and map the data modulation symbols to the corresponding modulation subsets. The active subcarrier index bit recovery unit is used to convert the active candidate position into an active position subset, merge the active position subset with the modulation subset, and recover the active subcarrier index bit.

[0104] This invention also provides an electronic device, including a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the various processes of the above-described embodiments of the orthogonal frequency division multiplexing communication method based on dual-dimensional index modulation and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0105] It should be noted that the electronic devices in the embodiments of the present invention include the mobile electronic devices and non-mobile electronic devices described above.

[0106] This invention also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described embodiments of the orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0107] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0108] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0109] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0110] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0111] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. An orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, characterized in that, Applied to the sending end, the method includes: Obtain the bitstream; Generate an orthogonal frequency division multiplexing (OFDM) baseband signal; the OFDM baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset is used to indicate the position of the pilot subcarrier, the pilot modulation subset is used to generate pilot modulation symbols, and the pilot index bits are determined based on the bit stream; The orthogonal frequency division multiplexing (OFDM) baseband signal is sent to the receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal.

2. The orthogonal frequency division multiplexing communication method according to claim 1, characterized in that, The generation of the orthogonal frequency division multiplexing baseband signal includes: The bit stream is divided into pilot index bits and active subcarrier index bits; The pilot index bits are divided into a position selection subset and a pilot modulation subset; Based on the location selection subset indicated by the location, the corresponding subcarrier is selected from the preset subcarrier set as the pilot subcarrier; The pilot modulation subset is mapped to pilot modulation symbols and loaded onto the pilot subcarrier; In the subcarrier set excluding the pilot subcarrier, a corresponding subcarrier is selected as the active data subcarrier according to the active subcarrier index bit, and data modulation symbols are loaded on the active data subcarrier. The subcarriers in the subcarrier set, excluding the pilot subcarriers and the active data subcarriers, are set to zero to obtain the frequency domain signal vector; Based on the frequency domain signal vector, an orthogonal frequency division multiplexing baseband signal is generated.

3. The orthogonal frequency division multiplexing communication method according to claim 2, characterized in that, The step of selecting a corresponding subcarrier as an active data subcarrier from the subcarrier set excluding the pilot subcarrier, based on the active subcarrier index bit, and loading data modulation symbols on the active data subcarrier includes: The active subcarrier index bits are divided into an active position subset and a modulation subset. The active position subset is used to indicate the position of the active data subcarrier, and the modulation subset is used to generate data modulation symbols. In the subcarrier set excluding the pilot subcarrier, the corresponding subcarrier is selected as the active data subcarrier according to the active data subcarrier position indicated by the active position subset; The modulation subset is mapped to data modulation symbols and loaded into the active data subcarrier.

4. The orthogonal frequency division multiplexing communication method according to claim 2, characterized in that, The subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the position selection subset is used to indicate the position of the pilot subcarriers in each sub-block; The step of selecting pilot subcarrier positions from a preset set of subcarriers based on the selected location subset includes: Within each sub-block, the pilot subcarrier position indicated by the selected subset is chosen according to the position, and the corresponding subcarrier is selected as the pilot subcarrier.

5. The orthogonal frequency division multiplexing communication method according to claim 1, characterized in that, The pilot modulation symbol is the BPSK modulation symbol.

6. The orthogonal frequency division multiplexing communication method according to claim 2, characterized in that, The step of generating an orthogonal frequency division multiplexing baseband signal based on the frequency domain signal vector includes: Perform an inverse fast Fourier transform on the frequency domain signal vector to obtain a time-domain orthogonal frequency division multiplexing symbol; A cyclic prefix is ​​configured before the time-domain orthogonal frequency division multiplexing symbol to obtain the orthogonal frequency division multiplexing baseband signal.

7. An orthogonal frequency division multiplexing communication method based on two-dimensional index modulation, characterized in that, Applied to the receiving end, the method includes: Receives orthogonal frequency division multiplexing baseband signals; Based on the orthogonal frequency division multiplexing baseband signal, the bit stream is recovered; the orthogonal frequency division multiplexing baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset corresponds to the position of the pilot subcarrier in the orthogonal frequency division multiplexing baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

8. The orthogonal frequency division multiplexing communication method according to claim 7, characterized in that, The process of recovering the bit stream based on the orthogonal frequency division multiplexing baseband signal includes: The orthogonal frequency division multiplexing baseband signal is synchronized and subjected to fast Fourier transform to obtain the frequency domain received signal; Based on the frequency domain received signal, the position of the pilot subcarrier is detected and the pilot modulation symbol is demodulated to recover the pilot index bit; In the preset subcarrier set excluding the pilot subcarrier, the position of the active data subcarrier is identified and the data modulation symbol is demodulated to recover the active subcarrier index bit; The pilot index bits and the active subcarrier index bits are combined to restore the bit stream.

9. The orthogonal frequency division multiplexing communication method according to claim 8, characterized in that, The subcarrier set is divided into multiple non-overlapping sub-blocks, each sub-block containing multiple subcarriers; the step of detecting the position of the pilot subcarriers and demodulating the pilot modulation symbols based on the frequency domain received signal to recover the pilot index bits includes: Based on the frequency domain received signal, calculate the log-likelihood ratio of each subcarrier; Select the subcarrier with the largest log-likelihood ratio from each sub-block as the pilot candidate position; Based on the frequency domain received value at the pilot candidate position, the pilot modulation symbol is demodulated according to the first preset modulation mapping relationship, and the pilot modulation symbol is mapped to the corresponding pilot modulation subset; The pilot candidate positions are converted into a position selection subset, the position selection subset is merged with the pilot modulation subset, and the pilot index bits are recovered.

10. The orthogonal frequency division multiplexing communication method according to claim 9, characterized in that, The step of identifying the position of the active data subcarrier and demodulating the data modulation symbols in the subcarriers other than the pilot subcarriers in the preset subcarrier set to recover the active subcarrier index bit includes: Based on the frequency domain received signal, the log-likelihood ratio of each subcarrier is calculated on the subcarrier set excluding the pilot subcarrier; Select the position of the subcarrier with the largest log-likelihood ratio from each sub-block as the activation candidate position; Based on the frequency domain received value at the activated candidate position, the data modulation symbol is demodulated according to the second preset modulation mapping relationship, and the data modulation symbol is mapped to the corresponding modulation subset; The activation candidate positions are converted into an activation position subset, the activation position subset is merged with the modulation subset, and the activation subcarrier index bits are recovered.

11. An orthogonal frequency division multiplexing communication device based on two-dimensional index modulation, characterized in that, Applied to the transmitting end, the device includes: Bit stream acquisition module, used to acquire bit streams; An orthogonal frequency division multiplexing (OFDM) baseband signal generation module is used to generate an OFDM baseband signal; the OFDM baseband signal carries pilot index bits, the pilot index bits include a position selection subset and a pilot modulation subset, the position selection subset is used to indicate the position of the pilot subcarrier, the pilot modulation subset is used to generate pilot modulation symbols, and the pilot index bits are determined based on the bit stream; An orthogonal frequency division multiplexing (OFDM) baseband signal transmission module is used to transmit the OFDM baseband signal to a receiving end so that the receiving end can recover the bit stream based on the OFDM baseband signal.

12. An orthogonal frequency division multiplexing communication device based on two-dimensional index modulation, characterized in that, Applied to the receiving end, the device includes: Orthogonal Frequency Division Multiplexing (OFDM) baseband signal receiving module, used to receive OFDM baseband signals; A bitstream recovery module is used to recover a bitstream based on the orthogonal frequency division multiplexing (OFDM) baseband signal. The OFDM baseband signal carries pilot index bits, which include a position selection subset and a pilot modulation subset. The position selection subset corresponds to the position of the pilot subcarrier in the OFDM baseband signal, and the pilot modulation subset corresponds to the pilot modulation symbol on the pilot subcarrier.

13. An electronic device, characterized in that, It includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein when the program or instructions are executed by the processor, they implement the steps of the orthogonal frequency division multiplexing communication method based on two-dimensional index modulation as described in claims 1-6 or 7-10.

14. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions, which, when executed by a processor, implement the steps of the orthogonal frequency division multiplexing communication method based on two-dimensional index modulation as described in claims 1-6 or 7-10.

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