Index-based OTFS modulation method, modulation system and communication system

Abstract

The invention provides an index-based OTFS modulation method, a modulation system and a communication system. The method comprises the following steps: segmenting an input bit stream into a plurality of bit groups through a bit stream segmentation module; each bit group comprises index bits and symbol bits; performing index modulation on the plurality of bit groups to obtain a signal after index modulation; the signal after index modulation comprises index information for selecting an activation subcarrier through an index bit and a constellation symbol modulated on the activation subcarrier through a symbol bit; and carrying out ISFFT conversion and Hisenberg conversion on the signal after index modulation in the time delay-Doppler domain to obtain a time domain signal. According to the method, index and OTFS modulation are combined, so that system transmission in a high-speed moving scene has stability, the error rate and the complexity of a receiving end are reduced, the anti-interference capability is improved, and the method can be suitable for more complex application scenes.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to an index-based OTFS modulation method, a modulation system and a communication system. Background Art

[0002] In current wireless communication systems, OFDM (Orthogonal Frequency Division Multiplexing) is the most widely used multi-carrier modulation technology. It divides a given channel into many orthogonal sub-channels in the frequency domain, converts the high-speed data signal of the transmitter of the wireless communication system into parallel low-speed sub-data streams, and uses sub-carrier modulation to transmit in parallel on each sub-channel. Orthogonal signals can be separated by using correlation technology at the receiving end, which can reduce mutual interference between sub-channels. The signal bandwidth on each sub-channel is smaller than the correlation bandwidth of the channel, so each sub-channel can be regarded as flat fading, thereby eliminating inter-code interference, and because the bandwidth of each sub-channel is only a small part of the original channel bandwidth, channel equalization becomes relatively easy.

[0003] With the emergence of more complex scenarios of mobile Internet, OFDM in high-mobility scenarios, such as high-speed trains, interstellar communications and underwater communications, Doppler frequency shift will cause the channel to change rapidly, resulting in the loss of orthogonality between OFDM subcarriers and interference between subcarriers. This irregular fast time-varying channel will lead to an increase in the system's bit error rate and a decrease in anti-interference ability, and greatly increase the complexity of the receiving end. Summary of the invention

[0004] The present invention provides an index-based OTFS modulation method, modulation system and communication system, which are used to solve the defects of the system in the prior art that the bit error rate increases and the anti-interference ability decreases, and the complexity of the receiving end is greatly increased. The present invention combines index and OTFS modulation, so that the system transmission in high-speed mobile scenarios has stability, while reducing the bit error rate and the complexity of the receiving end, improving the anti-interference ability, and being applicable to more complex application scenarios.

[0005] The present invention provides an index-based OTFS modulation method, comprising: dividing an input bit stream of a transmitting end into a plurality of bit groups through a bit stream segmentation module; each bit group comprises an index bit and a symbol bit; performing index modulation on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of the activated subcarriers is determined according to a preset mapping table and the probability of the constellation symbol; the preset mapping table is a table of mapping relations between index bits and activated subcarriers; performing ISFFT transformation on the index-modulated signal in a delay-Doppler domain to obtain a time-frequency domain signal; performing Heisenberg transformation on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used for transmission on a fast time-varying signal so as to be received by a receiving end.

[0006] According to an index-based OTFS modulation method provided by the present invention, the index modulation of the multiple bit groups to obtain the index modulated signal includes: determining the number of the index bits and the number of the symbol bits in each of the bit groups; determining the available subcarrier set in the preset mapping table according to the number of index bits; mapping the symbol bits to data symbols, and determining the corresponding constellation symbols and the probability of the constellation symbols according to the data symbols; selecting the activated subcarrier from the subcarrier set according to the index bits and the probability of the constellation symbols; and mapping the constellation symbols to the activated subcarriers to form the index modulated signal.

[0007] According to an index-based OTFS modulation method provided by the present invention, the probability of the constellation symbol is expressed as:

[0008] in, For the i The data symbol is k The corresponding constellation symbol in the bit group a j The conditional probability of is the set of constellation modulation symbols, that is, all possible constellation symbols; is the index set of constellation symbols, ; For the i Data symbols correspond to constellation symbols a j The original probability of For all possible constellation symbols a j The original probabilities are summed.

[0009] According to an index-based OTFS modulation method provided by the present invention, the selecting the activated subcarrier from the subcarrier set according to the index bit and the probability of the constellation symbol includes: sorting the probabilities of the constellation symbols corresponding to all values ​​of each of the data symbols in order from large to small to obtain a sorting result; selecting the activated subcarrier from the subcarrier set according to the index bit and the sorting result; wherein the number of activated subcarriers corresponding to the probability sorted first is greater than the number of activated subcarriers corresponding to the probability sorted later.

[0010] According to an index-based OTFS modulation method provided by the present invention, the expansion function in the delay-Doppler domain is:

[0011] in, is the delay-Doppler domain spread function, is the time-frequency domain-time-varying transfer function, v , represents the Doppler shift, where v What is affected is the time dimension of the time-frequency domain channel. It represents the frequency dimension in the time-frequency domain channel. t For time, f is the frequency.

[0012] The present invention also provides an index-based OTFS modulation system, comprising: a bit stream segmentation module, used to segment the input bit stream of the transmitting end into multiple bit groups; each bit group includes an index bit and a symbol bit; an index modulation module, used to perform index modulation on the multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of constellation symbols; the preset mapping table is a table of mapping relations between index bits and activated subcarriers; a first transformation module, used to perform ISFFT transformation on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; a second transformation module, used to perform Heisenberg transformation on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to be transmitted on a fast time-varying signal so that it can be received by a receiving end.

[0013] The present invention also provides an index-based OTFS communication system, comprising the above-mentioned index-based OTFS modulation system and an OTFS demodulation system; the OTFS demodulation system is used to perform OTFS demodulation on the time domain signal so that the receiving end can receive it.

[0014] According to an index-based OTFS communication system provided by the present invention, the OTFS demodulation system includes: a third transformation module, used to perform Wigner transformation on the time domain signal to obtain the time-frequency domain signal; a fourth transformation module, used to perform SFFT transformation on the time-frequency domain signal to obtain an index-modulated signal in the delay-Doppler domain; an index demodulation module, used to perform index demodulation on the index-modulated signal to obtain a plurality of bit groups; a bit stream paralleling module, used to parallel the plurality of bit groups to obtain an output bit stream for reception by the receiving end.

[0015] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the index-based OTFS modulation method described above is implemented.

[0016] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the index-based OTFS modulation method described above is implemented.

[0017] The present invention provides an index-based OTFS modulation method, modulation system and communication system, the method comprising: dividing an input bit stream into multiple bit groups through a bit stream segmentation module; each bit group includes an index bit and a symbol bit; performing index modulation on the multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information of an activated subcarrier selected by the index bit and a constellation symbol modulated on the activated subcarrier by the symbol bit; performing ISFFT transformation and Heisenberg transformation on the index-modulated signal in the delay-Doppler domain to obtain a time domain signal. The present invention combines index and OTFS modulation, so that the system transmission in high-speed mobile scenarios has stability, while reducing the bit error rate and the complexity of the receiving end, improving the anti-interference ability, and being applicable to more complex application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a flow chart of an index-based OTFS modulation method provided by the present invention.

[0020] Figure 2 It is a schematic diagram of the principle of an index-based OTFS modulation method provided by the present invention.

[0021] Figure 3 It is a schematic diagram of the conversion domain of the OTFS signal provided by the present invention.

[0022] Figure 4 It is a structural schematic diagram of an index-based OTFS modulation system provided by the present invention.

[0023] Figure 5 It is a structural diagram of an index-based OTFS communication system provided by the present invention.

[0024] Figure 6 It is a schematic diagram of the principle of an index-based OTFS communication system provided by the present invention.

[0025] Figure 7 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In wireless communication systems, due to the flexible physical access of orthogonal frequency division multiplexing, the combination of new coding and multi-carrier technology has achieved high-speed, low-latency and large-scale access of wireless communication. At the same time, it has the ability to resist interference during the transmission process, ensuring the reliability of data transmission. It has been widely used in current communication standards and is now the main modulation method. OFDM divides the given channel within the frequency into many sub-channels, and each sub-channel remains orthogonal. High-speed data streams are allocated to multiple orthogonal sub-channels for transmission, thereby greatly reducing the symbol rate on the sub-channel and lengthening the duration of a single data symbol. Therefore, it increases the rate of the wireless communication system, reduces latency, has anti-interference ability, and reduces inter-code interference. However, in high-speed mobile scenarios, OFDM does not have stability. In this scenario, the transmission has a large bit error rate and weak anti-interference ability.

[0028] Considering that the traditional OFDM multi-carrier modulation technology loses orthogonality between subcarriers in high-speed mobile scenarios, it will cause mutual interference between subcarriers, which will eventually lead to an increase in bit error rate and weak anti-interference ability. At the same time, it increases the complexity of the receiving end. OFDM is not stable in high-speed mobile scenarios. In order to solve the technical problems existing in the prior art, the present invention combines index and OTFS modulation in high-speed mobile scenarios, and calculates the number of subcarriers that need to be activated according to the probability of constellation symbols for the subcarriers, thereby effectively avoiding the waste of resources for activating carriers, and solving the problems of low bit error rate and unstable performance caused by non-orthogonal subcarriers of OFDM in high-speed mobile scenarios. The OTFS (Orthogonal TimeFrequency Space) technology includes preprocessing and post-processing, which converts the fast time-varying channel in the time domain into a channel with almost constant gain in the Delay Doppler (DD) domain. Since it is independent of time in the DD domain, channel estimation can be accurately performed in high-speed mobile scenarios. Therefore, OTFS can improve throughput and reliability in high-speed mobile and some irregular fast time-varying channel scenarios, while avoiding interference between carriers. At the same time, Index Modulation (IM) technology is a spatial modulation technology with high spectrum efficiency and high energy efficiency. According to the index modulation bit information, through the mapping relationship table, the subcarrier is selected to activate and send bit data, while the unactivated subcarrier is in a silent state. Through constellation symbol carrier transmission, the modulation technology based on index and OTFS can reduce the energy reduction, improve the bit error rate and efficiency of the system, and has strong anti-interference ability in high-speed mobile scenarios.

[0029] Please refer to Figure 1 , Figure 1 A schematic flow chart of an index-based OTFS modulation method provided by the present invention.

[0030] Please refer to Figure 2 , Figure 2 A schematic diagram of the principle of an index-based OTFS modulation method provided by the present invention.

[0031] The present invention provides an index-based OTFS modulation method, comprising: 101: Split the input bit stream of the transmitter into multiple bit groups through a bit stream splitting module; each bit group includes an index bit and a sign bit.

[0032] In this embodiment, the m The bits are divided into n groups, each group bits, p The bits are divided into index bits and sign bit The index bit and sign bit After index selection and constellation symbol mapping, such as table lookup mapping method, the same table needs to be created at the transmitter and receiver to define the mapping relationship between index bits and activated subcarriers. The size of the table is , this table details the index bits and activated subcarriers k The mapping relationship between the index combinations between subcarriers K =4, activated subcarrier k =2, then The number of combinations C(4,2)=6, which means there are 6 different ways to select 2 subcarriers from 4 subcarriers. Therefore, there are 2 unused activated subcarriers. After index modulation, the signal is OTFS modulated and then output.

[0033] 102: Index modulate multiple bit groups to obtain an index modulated signal; the index modulated signal includes index information for selecting an activated subcarrier through index bits and a constellation symbol modulated on the activated subcarrier through symbol bits; the number of activated subcarriers is determined according to a preset mapping table and a probability of the constellation symbol; the preset mapping table is a table of mapping relationships between index bits and activated subcarriers.

[0034] As a preferred embodiment, multiple bit groups are index-modulated to obtain an index-modulated signal, including: determining the number of index bits and the number of symbol bits in each bit group; determining a set of available subcarriers in a preset mapping table according to the number of index bits; mapping the symbol bits to data symbols, and determining corresponding constellation symbols and the probability of constellation symbols according to the data symbols; selecting an activated subcarrier from a subcarrier set according to the index bits and the probability of constellation symbols; and mapping the constellation symbols to the activated subcarriers to form an index-modulated signal.

[0035] As a preferred embodiment, the probability of the constellation symbol is expressed as:

[0036] in, For the i The data symbol is k The corresponding constellation symbol in the bit group a j The conditional probability of is the set of constellation modulation symbols, that is, all possible constellation symbols; is the index set of constellation symbols, ; For thei Data symbols correspond to constellation symbols a j The original probability of For all possible constellation symbols a j The original probabilities are summed.

[0037] As a preferred embodiment, an activated subcarrier is selected from a subcarrier set according to the index bit and the probability of the constellation symbol, including: sorting the probabilities of the constellation symbols corresponding to all values ​​of each data symbol in order from large to small to obtain a sorting result; selecting an activated subcarrier from the subcarrier set according to the index bit and the sorting result; wherein the number of activated subcarriers corresponding to the probability sorted first is greater than the number of activated subcarriers corresponding to the probability sorted later.

[0038] In this embodiment, the number of index bits and the number of symbol bits in each bit group are first determined, and then the available subcarrier set in the preset mapping table is determined according to the number of index bits. For example, if the system has eight subcarriers, the index bits indicate the activation of subcarrier one and subcarrier three according to the mapping table. The symbol bits are mapped to data symbols. For example, using a 16-QAM constellation diagram, the symbol bits P 2i Corresponding data symbol S i Mapping to constellation points A si , the constellation point has a specific amplitude and phase. According to the probability of the index bit and the constellation symbol, the activated subcarrier is selected from the subcarrier set. The constellation symbol is then mapped to the activated subcarrier to form an index modulated signal.

[0039] Index modulation will cause unactivated data symbols to appear in the data frame. In index modulation, there will be multiple invalid carriers. At the same time, the number of activated carriers in each group is different, and the distribution of data symbols in each group is not uniform. Therefore, if the average distribution is adopted, the activated subcarriers of the bit group with fewer data symbols will be wasted. In this embodiment, the probability of data symbols in each bit group is used to sort all bit groups, and the number of activated subcarriers in each bit group is reasonably allocated according to the probability. Index modulation and constellation symbol mapping are used to obtain index information and corresponding constellation symbols (index modulated signals). The specific steps are: first, calculate the probability that all values ​​of each data symbol in each bit group correspond to the constellation symbol; then sort the probabilities of all values ​​of each data symbol being constellation symbols, and k Bit group i All values ​​of the data symbols are sorted, and the result is:

[0040] in,( For the i The data symbol is k The corresponding constellation symbol in the bit group a j The conditional probability of is the set of constellation modulation symbols It is the event with the i-th index in the first bit group, and the following is similar, used to calculate the probability, refer to the calculation formula).

[0041] Then k The subcarriers are activated according to the probability of the constellation symbol. The number of activated subcarriers corresponding to the probability of the first order is greater than the number of activated subcarriers corresponding to the probability of the last order, that is, The greater the probability, the greater the proportion of data symbols in the bit group, and the more subcarriers need to be activated during the index adjustment process. The smaller the probability, the smaller the proportion of data symbols representing the bit group, so the required subcarrier is smaller, thus avoiding the waste of subcarrier resources and improving the performance of the system.

[0042] During the modulation process, the original data (bit stream) is converted into signal forms that can be transmitted on a physical channel. These signal forms are data symbols, which can be real or complex numbers, depending on the modulation technique.

[0043] In digital communications, a constellation symbol refers to the distribution of points on the complex plane that represent data bits during the modulation process of a signal. These points are usually located at specific coordinate positions, and each point corresponds to a specific bit pattern or symbol value.

[0044] OTFS modulation technology is used in high-speed mobile wireless communication scenarios. It maps the data symbols to be sent to the delay-Doppler domain and transmits data in this domain. In time transmission, signals are transmitted in the time domain, so it is necessary to perform a two-way conversion between the delay-Doppler domain and the time-frequency domain. First, the information symbol x[k,l] is mapped to the sample x[n,m] in the time-frequency domain through the ISFFT transformation, and then through the Heisenberg transformation, the time domain signal y(t) transmitted on the fast wireless channel is generated.

[0045] 103: Perform ISFFT transformation on the index modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal.

[0046] 104: Perform Heisenberg transform on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used for transmission on the fast time-varying signal so as to be received by a receiving end.

[0047] As a preferred embodiment, the expansion function in the delay-Doppler domain is:

[0048] in, is the delay-Doppler domain spread function, is the time-frequency domain-time-varying transfer function, v , represents the Doppler shift, where v What is affected is the time dimension of the time-frequency domain channel. It represents the frequency dimension in the time-frequency domain channel. t For time, f is the frequency.

[0049] Please refer to Figure 3 , Figure 3 A schematic diagram of the conversion domain of the OTFS signal provided by the present invention.

[0050] Considering that the transmitted signal will be affected by the linear time-varying system when passing through the channel, in this embodiment, the delay domain-time-varying impulse response is used. , which represents the change of impulse response in the time domain, time-frequency domain-time-varying transfer function , which represents the change of the channel in the time-frequency domain, the delay-Doppler domain spread function , which represents the change of the channel in the delay-Doppler domain. These three modes can be transformed into each other, and the corresponding relationship is:

[0051] function and The conversion relationship is:

[0052] Using two-dimensional Fourier transform, we can get and conversion relationship.

[0053] The signal x[k,l] in the delay-Doppler domain after index modulation is mapped to the time domain in two steps. First, it is mapped to the time-frequency domain using the Inverse Symplectic Finite Fourier transform (ISFFT), and then mapped to the time domain using the Heisenberg transform. X[k,l] is mapped to the time-frequency domain through the following changes;

[0054] After being mapped to the time domain x(t) through the Heisenberg transform, the signal can be transmitted over a fast time-varying channel.

[0055]

[0056] Among them, k and l are Doppler and delay grid indexes, N and M are the number of Doppler and delay grids, n and m are time and frequency grid indexes, and T are the subcarrier spacing and symbol period, respectively.

[0057] In summary, in the high-speed mobile scenario, the present invention calculates the index information and constellation symbols of the number of subcarriers that need to be activated according to the probability of the constellation symbols for the subcarriers during the index and OTFS modulation process of the transmitter signal of the wireless communication, and converts the signal in the time domain into a signal in the delay-Doppler domain after the ISSFT operation, which is independent of time and does not affect the orthogonal characteristics of the subcarriers. Combined with the high energy and high efficiency characteristics of the index modulation technology, the energy attenuation of the signal transmission process is slow, and the advantages of the index and OTFS are combined, so that the system transmission in the high-speed mobile scenario is stable, while reducing the bit error rate and enhancing the anti-interference ability, and can be used in more complex application scenarios.

[0058] The index-based OTFS modulation system provided by the present invention is described below. The index-based OTFS modulation system described below and the index-based OTFS modulation method described above can be referred to each other.

[0059] Please refer to Figure 4 , Figure 4 A schematic structural diagram of an index-based OTFS modulation system provided by the present invention.

[0060] The present invention also provides an index-based OTFS modulation system, comprising: a bit stream segmentation module 1, used to segment the input bit stream of the transmitting end into multiple bit groups; each bit group includes an index bit and a symbol bit; an index modulation module 2, used to perform index modulation on the multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information of an activated subcarrier selected by the index bit and a constellation symbol modulated on the activated subcarrier by the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of the constellation symbol; the preset mapping table is a table of the mapping relationship between the index bit and the activated subcarrier; a first transformation module 3, used to perform an ISFFT transformation on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; a second transformation module 4, used to perform a Heisenberg transformation on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to be transmitted on a fast time-varying signal so that it can be received by a receiving end.

[0061] The index-based OTFS communication system provided by the present invention is described below. The index-based OTFS communication system described below and the index-based OTFS modulation method described above can be referred to each other.

[0062] Please refer to Figure 5 , Figure 5 A schematic diagram of the structure of an index-based OTFS communication system provided by the present invention.

[0063] Please refer to Figure 6 , Figure 6 A schematic diagram of the principle of an index-based OTFS communication system provided by the present invention.

[0064] The present invention also provides an index-based OTFS communication system, comprising the above-mentioned index-based OTFS modulation system and an OTFS demodulation system; the OTFS demodulation system is used to perform OTFS demodulation on the time domain signal so that the receiving end can receive it.

[0065] As a preferred embodiment, the OTFS demodulation system includes: a third transformation module 5, which is used to perform a Wigner transform on a time domain signal to obtain a time-frequency domain signal; a fourth transformation module 6, which is used to perform a SFFT transform on the time-frequency domain signal to obtain an index-modulated signal in the delay-Doppler domain; an index demodulation module 7, which is used to perform index demodulation on the index-modulated signal to obtain multiple bit groups; a bit stream paralleling module 8, which is used to parallel multiple bit groups to obtain an output bit stream for reception by a receiving end.

[0066] In this embodiment, the receiving end first receives the time domain signal transmitted through the channel, and the third transformation module 5 is responsible for performing Wigner transform on the time domain signal to obtain the time-frequency domain signal. The time-frequency domain signal after Wigner transform is sent to the fourth transformation module 6, which performs SFFT (Fast Fourier Inverse Transform) to convert the signal from the time-frequency domain to the delay-Doppler domain. The index demodulation module 7 is responsible for processing the signal in the delay-Doppler domain to identify the activated subcarriers and the corresponding constellation symbols. Once the index demodulation module recovers multiple bit groups, the bit stream parallel module 8 recombine these bit groups into an output bit stream. This process involves re-parallelizing the bits scattered in different subcarriers and delay-Doppler domains to restore the original bit stream, which can maintain high data transmission quality and reliability even in a high-speed mobile environment.

[0067] Figure 7 An example of a structural diagram of an electronic device is shown in FIG. Figure 7As shown, the electronic device may include: a processor (processor) 710 , a communication interface (Communications Interface) 720 , a memory (memory) 730 and a communication bus 740 , wherein the processor 710 , the communication interface 720 , and the memory 730 communicate with each other through the communication bus 740 . The processor 710 can call the logic instructions in the memory 730 to execute the index-based OTFS modulation method, which includes: dividing the input bit stream of the transmitter into multiple bit groups through a bit stream segmentation module; each bit group includes an index bit and a symbol bit; performing index modulation on the multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of the constellation symbol; the preset mapping table is a table of the mapping relationship between the index bit and the activated subcarrier; performing an ISFFT transform on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; performing a Heisenberg transform on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to transmit on a fast time-varying signal so that the receiving end can receive it.

[0068] In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0069] On the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the index-based OTFS modulation method provided by the above methods, which includes: dividing the input bit stream of the transmitter into multiple bit groups through a bit stream segmentation module; each bit group includes an index bit and a symbol bit; index modulating the multiple bit groups to obtain index modulated signals; the index modulated signal includes index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of the constellation symbol; the preset mapping table is a table of the mapping relationship between the index bit and the activated subcarrier; performing an ISFFT transform on the index modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; performing a Heisenberg transform on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to transmit on a fast time-varying signal so that it can be received by the receiving end.

[0070] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented by a processor to execute the index-based OTFS modulation method provided by the above-mentioned methods when executed, the method comprising: dividing the input bit stream of the transmitter into multiple bit groups through a bit stream segmentation module; each bit group includes an index bit and a symbol bit; index modulating the multiple bit groups to obtain index modulated signals; the index modulated signal includes index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of the constellation symbol; the preset mapping table is a table of the mapping relationship between the index bit and the activated subcarrier; performing an ISFFT transform on the index modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; performing a Heisenberg transform on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used for transmission on a fast time-varying signal so that it can be received by a receiving end.

[0071] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0072] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An index-based OTFS modulation method, characterized in that: include: The input bit stream of the transmitting end is divided into a plurality of bit groups by a bit stream division module; each bit group includes an index bit and a sign bit; Index modulation is performed on the plurality of bit groups to obtain an index modulated signal; the index modulated signal includes index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and the probability of constellation symbols; the preset mapping table is a table of mapping relationships between index bits and activated subcarriers; Performing ISFFT transformation on the index modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; Performing Heisenberg transform on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to transmit on a fast time-varying signal so as to be received by a receiving end.

2. The index-based OTFS modulation method according to claim 1, characterized in that: The step of index modulating the plurality of bit groups to obtain an index modulated signal includes: Determining the number of the index bits and the number of the sign bits in each of the bit groups; Determining a subcarrier set available in the preset mapping table according to the number of index bits; Mapping the symbol bits to data symbols, and determining corresponding constellation symbols and probabilities of the constellation symbols according to the data symbols; Selecting the activated subcarrier from the subcarrier set according to the index bit and the probability of the constellation symbol; The constellation symbol is mapped to the activated subcarrier to form the index modulated signal.

3. The index-based OTFS modulation method according to claim 2, characterized in that: The probability of the constellation symbol is expressed as: in, For the i The data symbol is k The corresponding constellation symbol in the bit group a j The conditional probability of is the set of constellation modulation symbols, that is, all possible constellation symbols; is the index set of constellation symbols, ; For the i Data symbols correspond to constellation symbols a j The original probability of For all possible constellation symbols a j The original probabilities are summed.

4. The index-based OTFS modulation method according to claim 2, characterized in that: The selecting the activated subcarrier from the subcarrier set according to the probability of the index bit and the constellation symbol comprises: Sorting the probabilities of the constellation symbols corresponding to all values ​​of each of the data symbols in descending order to obtain a sorting result; The activated subcarrier is selected from the subcarrier set according to the index bit and the sorting result; wherein the number of activated subcarriers corresponding to the probability of the first sorting is greater than the number of activated subcarriers corresponding to the probability of the last sorting.

5. The index-based OTFS modulation method according to any one of claims 1 to 4, characterized in that: The expansion function in the delay-Doppler domain is: in, is the delay-Doppler domain spread function, is the time-frequency domain-time-varying transfer function, v , represents the Doppler shift, where v What is affected is the time dimension of the time-frequency domain channel. It represents the frequency dimension in the time-frequency domain channel. t For time, f is the frequency.

6. An index-based OTFS modulation system, characterized in that: include: A bit stream segmentation module, used for segmenting the input bit stream of the transmitting end into a plurality of bit groups; each bit group includes an index bit and a sign bit; An index modulation module, configured to perform index modulation on the plurality of bit groups to obtain an index modulated signal; the index modulated signal comprises index information for selecting an activated subcarrier through the index bit and a constellation symbol modulated on the activated subcarrier through the symbol bit; the number of activated subcarriers is determined according to a preset mapping table and a probability of constellation symbols; the preset mapping table is a table of mapping relationships between index bits and activated subcarriers; A first transformation module, used for performing ISFFT transformation on the index modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; The second transformation module is used to perform Heisenberg transformation on the time-frequency domain signal to obtain a time domain signal; the time domain signal is used to be transmitted on a fast time-varying signal so as to be received by a receiving end.

7. An index-based OTFS communication system, characterized in that: The invention comprises the index-based OTFS modulation system as described in claim 6, and also comprises an OTFS demodulation system; the OTFS demodulation system is used to perform OTFS demodulation on the time domain signal so that the receiving end can receive it.

8. The index-based OTFS communication system according to claim 7, characterized in that: The OTFS demodulation system comprises: A third transformation module, used for performing Wigner transformation on the time domain signal to obtain the time-frequency domain signal; A fourth transformation module, used for performing SFFT transformation on the time-frequency domain signal to obtain an index-modulated signal in the delay-Doppler domain; An index demodulation module, used to perform index demodulation on the index modulated signal to obtain a plurality of bit groups; The bit stream paralleling module is used to parallelize the multiple bit groups to obtain an output bit stream so that the receiving end can receive it.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the index-based OTFS modulation method according to any one of claims 1 to 5 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the index-based OTFS modulation method according to any one of claims 1 to 5 is implemented.

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