An index-based OTFS modulation method, modulation system and communication system

Abstract

The application provides an index-based OTFS modulation method, a modulation system and a communication system, and the method comprises the following steps: input bit streams are divided into multiple bit groups by a bit stream division module; each bit group comprises index bits and symbol bits; the multiple bit groups are subjected to index modulation to obtain an index-modulated signal; the index-modulated signal comprises index information for selecting and activating subcarriers by the index bits and constellation symbols modulated on the activated subcarriers by the symbol bits; and the index-modulated signal is subjected to ISFFT transformation and Heisenberg transformation in a time-delay-doppler domain to obtain a time-domain signal. The application combines index and OTFS modulation, so that the system transmission in a high-speed moving scene has stability, while the bit error rate and the complexity of the receiving end are reduced, the anti-interference capability is improved, and more complex application scenes can be applied.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, and particularly relates to an index-based OTFS modulation method, a modulation system and a communication system. BACKGROUND

[0002] In the current wireless communication system, OFDM (Orthogonal Frequency Division Multiplexing) is the most widely used multicarrier modulation technology, which divides the given channel into many orthogonal sub-channels in the frequency domain, converts the high-speed data signal of the transmitting end of the wireless communication system into parallel low-speed sub-data streams, and modulates the sub-carriers to perform parallel transmission on each sub-channel. The orthogonal signals can be separated by using correlation technology at the receiving end, which can reduce the mutual interference between sub-channels. The signal on each sub-channel has a bandwidth smaller than the correlation bandwidth of the channel, so each sub-channel can be considered as a flat fading channel, thereby eliminating the inter-symbol 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, in high-speed mobile scenarios such as high-speed trains, interstellar communication and underwater communication, the Doppler shift will cause the channel to change rapidly, resulting in the loss of orthogonality between the sub-carriers of OFDM, which causes interference between the sub-carriers. This irregular fast time-varying channel will cause the bit error rate of the system to rise and the anti-interference ability to decline, and greatly increase the complexity of the receiving end. SUMMARY

[0004] The present application provides an index-based OTFS modulation method, a modulation system and a communication system, to solve the defects of the prior art that the bit error rate of the system rises and the anti-interference ability declines, and the complexity of the receiving end is greatly increased. The present application 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 able to adapt to more complex application scenarios.

[0005] The application provides an index-based OTFS modulation method, comprising: dividing an input bit stream of a sending end into a plurality of bit groups through a bit stream division module; each bit group comprises index bits and symbol bits; index modulation is performed on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information of an active subcarrier selected through the index bits and constellation symbols modulated on the active subcarrier through the symbol bits; the number of the active subcarriers is determined according to a preset mapping table and a probability of the constellation symbols; the preset mapping table is a table of the mapping relationship between the index bits and the active subcarriers; ISFFT transformation is performed on the index-modulated signal in a delay-Doppler domain to obtain a time-frequency domain signal; a Heisenberg transformation is performed on the time-frequency domain signal to obtain a time domain signal; and the time domain signal is used for transmission on a fast time-varying signal to enable a receiving end to receive.

[0006] According to the index-based OTFS modulation method provided by the application, the index modulation performed on the plurality of bit groups to obtain an index-modulated signal comprises: determining the number of the index bits and the number of the symbol bits in each bit group; determining a set of available subcarriers in the preset mapping table according to the number of the index bits; performing data symbol mapping on the symbol bits, and determining corresponding constellation symbols and a probability of the constellation symbols according to the data symbols; selecting the active subcarriers from the set of subcarriers according to the index bits and the probability of the constellation symbols; and mapping the constellation symbols onto the active subcarriers to form the index-modulated signal.

[0007] According to the index-based OTFS modulation method provided by the application, the probability of the constellation symbols is represented as:

[0008]

[0009] wherein, is a conditional probability of a corresponding constellation symbol i of a data symbol k in a bit group a j . is a set of constellation modulation symbols, i.e., all possible constellation symbols; is an index set of the constellation symbols, . is an original probability of a corresponding constellation symbol i of a data symbol a j . is a sum of the original probabilities of all possible constellation symbols a j .

[0010] According to the index-based OTFS modulation method provided by the application, the activated subcarriers are selected from the subcarrier set according to the index bits and the probabilities of the constellation symbols, and the method comprises the following steps: the probabilities of the constellation symbols corresponding to all values of each data symbol are sorted in descending order to obtain a sorting result; and the activated subcarriers are selected from the subcarrier set according to the index bits and the sorting result; wherein the number of activated subcarriers corresponding to the probabilities in the front of the sorting result is greater than the number of activated subcarriers corresponding to the probabilities in the rear of the sorting result.

[0011] According to the index-based OTFS modulation method provided by the application, the delay-Doppler domain extension function is:

[0012]

[0013] wherein, is the delay-Doppler domain extension function, is a time-frequency domain-time-varying transfer function, v , represents a Doppler shift, wherein v affects the time dimension of the time-frequency domain channel, represents the frequency dimension on the time-frequency domain channel, t is time, f is frequency.

[0014] The application further provides an index-based OTFS modulation system, comprising: a bit stream segmentation module configured to segment an input bit stream of a sending end into a plurality of bit groups; each bit group comprises index bits and symbol bits; 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 of activated subcarriers selected by the index bits and constellation symbols modulated on the activated subcarriers by the symbol bits; the number of activated subcarriers is determined according to a preset mapping table and the probabilities of the constellation symbols; the preset mapping table is a table of mapping relationship between index bits and activated subcarriers; a first transformation module configured to perform ISFFT transformation on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; and a second transformation module configured to perform 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 to enable a receiving end to receive.

[0015] The application further provides an index-based OTFS communication system, comprising the index-based OTFS modulation system described above, and further comprising an OTFS demodulation system; the OTFS demodulation system is configured to perform OTFS demodulation on the time domain signal to enable the receiving end to receive.

[0016] The OTFS communication system based on indexes provided by the application comprises: a third transformation module, configured to perform Wigner transformation on the time domain signal to obtain the time-frequency domain signal; a fourth transformation module, configured to perform SFFT transformation on the time-frequency domain signal to obtain the index-modulated signal in the time-delay-Doppler domain; an index demodulation module, configured to perform index demodulation on the index-modulated signal to obtain a plurality of bit groups; and a bit stream parallel stream module, configured to parallelize the plurality of bit groups to obtain an output bit stream to be received by the receiving end.

[0017] The application further provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the OTFS modulation method based on indexes according to any one of the above when executing the computer program.

[0018] The application further provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program is executable on a processor to implement the OTFS modulation method based on indexes according to any one of the above.

[0019] The application provides an OTFS modulation method, a modulation system and a communication system based on indexes, which comprises: dividing an input bit stream into a plurality of bit groups by a bit stream division module; each bit group comprises index bits and symbol bits; performing index modulation on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information for selecting and activating subcarriers by the index bits and constellation symbols modulated on the activated subcarriers by the symbol bits; performing ISFFT transformation and Heisenberg transformation on the index-modulated signal in the time-delay-Doppler domain to obtain a time domain signal. The application combines index and OTFS modulation, so that the system transmission in a high-speed moving scenario has stability, while the bit error rate and the complexity of the receiving end are reduced, the anti-interference ability is improved, and more complex application scenarios can be applied. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 is a flowchart of the OTFS modulation method based on indexes provided by the application.

[0022] Figure 2 is a principle diagram of the OTFS modulation method based on indexes provided by the application.

[0023] Figure 3 is a transform domain schematic diagram of the OTFS signal provided by the present application.

[0024] Figure 4 is a structure schematic diagram of an index-based OTFS modulation system provided by the present application.

[0025] Figure 5 is a structure schematic diagram of an index-based OTFS communication system provided by the present application.

[0026] Figure 6 is a principle schematic diagram of an index-based OTFS communication system provided by the present application.

[0027] Figure 7 is a structure schematic diagram of an electronic device provided by the present application. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0029] In a wireless communication system, due to the flexible physical access of orthogonal frequency division multiplexing, the combination of new coding and multi-carrier technology realizes high rate, low delay and large-scale access of wireless communication, and has anti-interference ability in the transmission process, ensuring the reliability of data transmission, and has been widely used in current communication standards, and is the main modulation mode at present. OFDM is to divide the channel given in the frequency into many sub-channels, and the sub-channels maintain orthogonality. The high-speed data stream is allocated to multiple orthogonal sub-channels for transmission, so that the symbol rate on the sub-channel is greatly reduced, and the duration of a single data symbol is lengthened, so it improves the rate of the wireless communication system, reduces the delay, and has anti-interference ability to reduce the inter-symbol interference. However, in the high-speed mobile scene, OFDM does not have stability, and transmission in this scene has a large bit error rate and weak anti-interference ability.

[0030] Considering that the traditional OFDM multicarrier modulation technology loses orthogonality between subcarriers in a high-speed mobile scene, which causes mutual interference between subcarriers and finally causes the bit error rate to rise, the anti-interference ability is weak, and the complexity of the receiving end is increased, and OFDM does not have stability in a high-speed mobile scene. In order to solve the technical problems existing in the prior art, the index and OTFS modulation are combined in a high-speed mobile scene, the number of subcarriers to be activated is calculated according to the probability of constellation symbols, the resource waste of activated carriers is effectively avoided, and the problems of low bit error rate and unstable performance of OFDM subcarriers in a high-speed mobile scene are solved. The OTFS (Orthogonal Time Frequency Space) technology includes preprocessing and post-processing, and a fast time-varying channel in the time domain is changed into a channel with almost constant gain in the Delay Doppler (DD) domain. Since the channel in the DD domain is independent of time, channel estimation can be accurately performed in a high-speed mobile scene, so that OTFS can improve throughput and reliability in a high-speed mobile and some irregular fast time-varying channel scene, and interference between carriers is avoided. Meanwhile, the index modulation (Index Modulation, IM) technology is a kind of spatial modulation technology with high spectrum efficiency and high energy efficiency. According to the index modulation bit information, the subcarriers are selected to be activated and transmit bit data through a mapping relationship table, and the subcarriers that are not activated are in a silent state. Through constellation symbol carrier transmission, the modulation technology based on index and OTFS can reduce energy reduction, improve the bit error rate and efficiency of the system, and has strong anti-interference ability in a high-speed mobile scene.

[0031] Please refer to Figure 1 , Figure 1 A flowchart of an OTFS modulation method based on an index provided by the application.

[0032] Please refer to Figure 2 , Figure 2 A principle diagram of an OTFS modulation method based on an index provided by the application.

[0033] The application provides an OTFS modulation method based on an index, comprising:

[0034] 101: divide the input bit stream of the sending end into a plurality of bit groups through a bit stream division module; each bit group includes index bits and symbol bits.

[0035] In this embodiment, the m bits to be transmitted are divided into n groups by a bit stream division module, each group has bits, pBits are divided into index bits and symbol bits The index bits and symbol bits After index selection and constellation symbol mapping, such as using a lookup table mapping method, the same table needs to be created at both the transmitter and receiver to define the mapping relationship between index bits and active subcarriers. The size of the table is... This table lists the index bits in detail. and activate subcarrier k The mapping relationship between index combinations. For example, when subcarriers... K =4, active subcarrier k =2, then The combination number C(4,2)=6, which means there are 6 different ways to select 2 subcarriers from 4 subcarriers. Therefore, there are 2 unused active subcarriers. After index modulation, the signal is then subjected to OTFS modulation and output.

[0036] 102: Index modulation is performed on multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information for selecting active subcarriers through index bits and constellation symbols modulated on the active subcarriers through symbol bits; the number of active subcarriers is determined according to a preset mapping table and the probability of constellation symbols; the preset mapping table is a table of the mapping relationship between index bits and active subcarriers.

[0037] In a preferred embodiment, index modulation is performed on multiple bit groups to obtain an index-modulated signal, including: determining the number of index bits and the number of symbol bits in each bit group; determining the set of subcarriers available in a preset mapping table based on the number of index bits; mapping the symbol bits to data symbols and determining the corresponding constellation symbols and their probabilities based on the data symbols; selecting an active subcarrier from the subcarrier set based on the index bits and their probabilities; and mapping the constellation symbols onto the active subcarriers to form the index-modulated signal.

[0038] As a preferred embodiment, the probability of a constellation symbol is expressed as follows:

[0039]

[0040] in, For the first i The data symbol in the th k The constellation symbol in each bit group a j The conditional probability; It is the set of zodiac modulation symbols, that is, all possible zodiac symbols; A set of indices for constellation symbols. ; For the first i Each data symbol corresponds to a constellation symbol. a j The original probability; For all possible constellation symbols a j The original probabilities are summed.

[0041] As a preferred embodiment, selecting an active subcarrier from the subcarrier set based on the probabilities of the index bits and constellation symbols includes: sorting the probabilities of the constellation symbols corresponding to all values ​​of each data symbol in descending order to obtain a sorting result; selecting an active subcarrier from the subcarrier set based on the index bits and the sorting result; wherein the number of active subcarriers corresponding to probabilities that are ranked higher is greater than the number of active subcarriers corresponding to probabilities that are ranked lower.

[0042] In this embodiment, the number of index bits and symbol bits in each bit group are first determined. Then, based on the number of index bits, the set of subcarriers available in a preset mapping table is determined. For example, if the system has eight subcarriers, the index bits activate subcarrier one and subcarrier three according to the mapping table. Symbol bits are mapped using data symbols. For example, using a 16-QAM constellation diagram, the symbol bits... P 2i Corresponding data symbols S i Mapped to constellation points A si The constellation points have specific amplitudes and phases. Based on the probabilities of the index bits and constellation symbols, active subcarriers are selected from the subcarrier set. The constellation symbols are then mapped onto the active subcarriers to form the index-modulated signal.

[0043] Indexed modulation can lead to inactive data symbols in data frames. In indexed modulation, multiple invalid carriers are generated, and the number of active carriers in each group varies, resulting in uneven distribution of data symbols. Therefore, an average allocation would waste the active subcarriers in bit groups with fewer data symbols. In this embodiment, the probability of data symbols in each bit group is ranked across all bit groups, and the number of active subcarriers in each bit group is allocated rationally according to probability. Indexed modulation and constellation symbol mapping are used to obtain index information and the corresponding constellation symbols (the index-modulated signal). The specific steps are: first, calculate the probability of each data symbol in each bit group corresponding to a constellation symbol for all possible values; then, sort the probabilities of each data symbol being a constellation symbol and... k The first bit group i Sort all the values ​​of each data symbol, and the result is:

[0044]

[0045] in,( For the first i The data symbol in the th k The constellation symbol in each bit group a j The conditional probability; A collection of constellation modulators For the i-th index in the first bit group event, and so on, the probability is calculated using the formula (refer to the calculation formula).

[0046] Then k Each subcarrier is activated based on the probability of its constellation symbol. The number of activated subcarriers corresponding to probabilities that appear earlier in the sequence is greater than the number of activated subcarriers corresponding to probabilities that appear later in the sequence. A higher probability indicates a larger proportion of data symbols in that bit group, and therefore more subcarriers need to be activated during index adjustment. Conversely, a higher probability indicates a lower probability. The lower the probability, the smaller the proportion of data symbols in the bit group, and therefore the smaller the number of subcarriers required. This avoids wasting subcarrier resources and improves system performance.

[0047] During modulation, the raw data (bit stream) is converted into a signal form that can be transmitted over a physical channel. These signal forms are data symbols, which can be real or complex numbers, depending on the modulation technique.

[0048] In digital communications, a constellation symbol refers to the distribution of points on the complex plane used to represent data bits during signal modulation. These points are typically located at specific coordinate positions, and each point corresponds to a specific bit pattern or symbol value.

[0049] OTFS modulation technology is applied in high-speed mobile wireless communication scenarios. It maps the data symbols to be transmitted to the delay-Doppler domain and transmits the data in this domain. In time transmission, the signal is transmitted in the time domain. Therefore, bidirectional conversion between the delay-Doppler domain and the time-frequency domain is required. First, the x[k,l] information symbol is mapped to the time-frequency domain sample x[n,m] through ISFFT transformation. Then, after Heisenberg transformation, the time domain signal y(t) transmitted on the fast wireless channel is generated.

[0050] 103: Perform ISFFT transform on the index-modulated signal in the time-delay-Doppler domain to obtain the time-frequency domain signal.

[0051] 104: Perform Heisenberg transform on the time-frequency domain signal to obtain the time-domain signal; the time-domain signal is used for transmission on fast time-varying signals so that the receiving end can receive it.

[0052] As a preferred embodiment, the delay-Doppler domain spreading function is:

[0053]

[0054] wherein, is the delay-Doppler domain spreading function, is the time-frequency domain-time varying transfer function, v , represents the Doppler shift, wherein v affects the time dimension of the time-frequency domain channel, represents the frequency dimension on the time-frequency domain channel, t is the time, f is the frequency.

[0055] Please refer to Figure 3 , Figure 3 is the conversion domain schematic diagram of the OTFS signal provided by the present application.

[0056] Considering that the transmitted signal will be affected by the linear time-varying system when passing through the channel, in the present embodiment, the delay domain-time varying impulse response , which represents the change of the impulse response in the time domain, the time-frequency domain-time varying transfer function , which represents the change of the channel in the time-frequency domain, the delay-Doppler domain spreading function , which represents the change of the channel in the delay-Doppler domain. The three modes can be converted to each other, and the corresponding relationship is:

[0057]

[0058] The conversion relationship of the functions and is:

[0059]

[0060] The conversion relationship of and can be obtained by using two-dimensional Fourier transform.

[0061] The x[k, l] delay-Doppler domain signal output after the signal passes through the index modulation is mapped to the time domain in two steps, first mapped to the time-frequency domain by using the inverse symplectic finite Fourier transform (ISFFT), and then mapped to the time domain by using the Heisenberg transform. X[k, l] is mapped to the time-frequency domain through the following changes:

[0062]

[0063] The signal can be transmitted on a fast time-varying channel through the Heisenberg transformation mapping to the time domain x(t).

[0064]

[0065] where k and l are Doppler, delay grid indexes, N and M are Doppler, delay grid numbers, n and m are time, frequency grid indexes, and T are subcarrier spacing and symbol period, respectively.

[0066] In summary, in the high-speed mobile scene, the transmitting end signal of wireless communication is subjected to index and OTFS modulation, the number of subcarriers to be activated is calculated according to the probability of constellation symbols, the index information and constellation symbols are generated, the signal on the time domain is changed into the signal on the delay-Doppler domain through ISSFT operation, the orthogonality of the subcarriers is not affected by time, the high energy and high efficiency characteristics of the index modulation technology are combined, the energy attenuation of the signal transmission process is slow, the advantages of the index and OTFS are combined, the system transmission in the high-speed mobile scene is stable, the bit error rate is reduced, and the anti-interference capability is enhanced, and more complex application scenes can be used.

[0067] The index-based OTFS modulation system provided by the present application is described below, and the index-based OTFS modulation system described below can be correspondingly referred to the index-based OTFS modulation method described above.

[0068] Please refer to Figure 4 , Figure 4 The structure diagram of an index-based OTFS modulation system provided by the present application.

[0069] The present application also provides an index-based OTFS modulation system, comprising: a bit stream segmentation module 1 for segmenting the input bit stream of the transmitting end into a plurality of bit groups; each bit group comprises index bits and symbol bits; an index modulation module 2 for index modulation on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information for selecting and activating subcarriers through the index bits and constellation symbols modulated on the activated subcarriers through the symbol bits; 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 the mapping relationship between the index bits and the activated subcarriers; a first transformation module 3 for ISFFT transformation on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; a second transformation module 4 for 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 to enable the receiving end to receive.

[0070] The index-based OTFS communication system provided by the present application is described below, and the index-based OTFS communication system described below can be correspondingly referred to the index-based OTFS modulation method described above.

[0071] Please refer to Figure 5 , Figure 5 The structure schematic diagram of the index-based OTFS communication system provided by the present application is shown in the figure.

[0072] Please refer to Figure 6 , Figure 6 The principle schematic diagram of the index-based OTFS communication system provided by the present application is shown in the figure.

[0073] The present application also provides an index-based OTFS communication system, which comprises the index-based OTFS modulation system described above, and further comprises an OTFS demodulation system; the OTFS demodulation system is used for OTFS demodulating the time domain signal, so that the receiving end receives.

[0074] As a preferred embodiment, the OTFS demodulation system comprises: a third transform module 5, which is used for Wigner transform of the time domain signal to obtain a time-frequency domain signal; a fourth transform module 6, which is used for SFFT transform of the time-frequency domain signal to obtain an index-modulated signal in the time-delay-Doppler domain; an index demodulation module 7, which is used for index demodulation of the index-modulated signal to obtain a plurality of bit groups; and a bit stream parallel stream module 8, which is used for parallel stream of the plurality of bit groups to obtain an output bit stream, so that the receiving end receives.

[0075] In the embodiment, the receiving end first receives the time domain signal transmitted through the channel, and the third transform module 5 is responsible for Wigner transform of the time domain signal to obtain a time-frequency domain signal. The time-frequency domain signal after Wigner transform is sent to the fourth transform module 6, which performs SFFT (inverse fast Fourier transform) to convert the signal from the time-frequency domain to the time-delay-Doppler domain. The index demodulation module 7 is responsible for processing the signal in the time-delay-Doppler domain to identify the activated subcarriers and the corresponding constellation symbols. Once the index demodulation module recovers a plurality of bit groups, the bit stream parallel stream module 8 recombines these bit groups into an output bit stream. This process involves recombining the bits scattered in different subcarriers and time-delay-Doppler domains to recover the original bit stream, so that high data transmission quality and reliability can be maintained even in a high-speed mobile environment.

[0076] Figure 7 An example of the structure schematic diagram of an electronic device is shown in the figure. Figure 7As shown, the electronic device can include a processor 710, a communications interface 720, a memory 730, and a communications bus 740, wherein the processor 710, the communications interface 720, and the memory 730 complete mutual communication through the communications bus 740. The processor 710 can invoke a logic instruction in the memory 730 to perform an index-based OTFS modulation method, which includes: dividing an input bit stream of a sending end into a plurality of bit groups through a bit stream division module; each bit group includes index bits and symbol bits; index modulating the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal includes index information of selecting an active subcarrier through the index bits and constellation symbols modulated on the active subcarrier through the symbol bits; the number of active subcarriers is determined according to a preset mapping table and the probability of the constellation symbols; the preset mapping table is a table of the mapping relationship between the index bits and the active subcarriers; performing ISFFT transformation on the index-modulated signal in the delay-Doppler domain to obtain a time-frequency domain signal; performing a 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 to enable a receiving end to receive.

[0077] In addition, the logic instruction in the memory 730 described above can be implemented in the form of a software functional unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0078] In another aspect, the present application also provides a computer program product comprising a computer program, which can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to perform the index-based OTFS modulation method provided by the above-mentioned methods, which comprises: dividing an input bit stream of a sending end into a plurality of bit groups by a bit stream division module; each bit group comprises index bits and symbol bits; performing index modulation on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information of selecting active subcarriers by the index bits and constellation symbols modulated on the active subcarriers by the symbol bits; the number of active subcarriers is determined according to a preset mapping table and the probability of the constellation symbols; the preset mapping table is a table of the mapping relationship between the index bits and the active subcarriers; performing ISFFT transformation on the index-modulated signal in the 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; and the time domain signal is used for transmission on a fast time-varying signal to enable a receiving end to receive.

[0079] In yet another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program can be executed by a processor to implement the index-based OTFS modulation method provided by the above-mentioned methods, which comprises: dividing an input bit stream of a sending end into a plurality of bit groups by a bit stream division module; each bit group comprises index bits and symbol bits; performing index modulation on the plurality of bit groups to obtain an index-modulated signal; the index-modulated signal comprises index information of selecting active subcarriers by the index bits and constellation symbols modulated on the active subcarriers by the symbol bits; the number of active subcarriers is determined according to a preset mapping table and the probability of the constellation symbols; the preset mapping table is a table of the mapping relationship between the index bits and the active subcarriers; performing ISFFT transformation on the index-modulated signal in the 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; and the time domain signal is used for transmission on a fast time-varying signal to enable a receiving end to receive.

[0080] The apparatus embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the present embodiment scheme according to actual needs. Those skilled in the art can understand and implement it without creative labor.

[0081] Those skilled in the art can clearly understand the implementation of the various embodiments by means of software and necessary general hardware platforms through the description of the above embodiments, and of course, the implementation can also be through hardware. Based on such understanding, the above technical solutions 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 a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the method described in each embodiment or some parts of the embodiment.

[0082] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An index-based OTFS modulation method, characterized in that, include: The input bitstream at the transmitting end is divided into multiple bit groups by the bitstream segmentation module; each bit group includes index bits and symbol bits. Multiple bit groups are index-modulated to obtain an index-modulated signal; the index-modulated signal includes index information for selecting active subcarriers through the index bits and constellation symbols modulated on the active subcarriers through the symbol bits; the number of active 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 active subcarriers; The index-modulated signal is subjected to ISFFT transformation in the time-delay-Doppler domain to obtain the time-frequency domain signal; The time-frequency domain signal is subjected to a Heisenberg transform 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 the receiving end. The step of performing index modulation on multiple bit groups to obtain an index-modulated signal includes: Determine the number of index bits and the number of symbol bits in each bit group; The set of subcarriers available in the preset mapping table is determined based on the number of index bits; The symbol bits are mapped to data symbols, and the corresponding constellation symbols and their probabilities are determined based on the data symbols. The active subcarrier is selected from the set of subcarriers based on the probability of the index bit and the constellation symbol; The constellation symbols are mapped onto the active subcarriers to form the index-modulated signal; The probability of the constellation symbol is expressed as follows: ； in, For the first i The data symbol in the th k The constellation symbol in each bit group a j The conditional probability; It is the set of zodiac modulation symbols, that is, all possible zodiac symbols; A set of indices for constellation symbols. ; For the first i Each data symbol corresponds to a constellation symbol. a j The original probability; For all possible constellation symbols a j Sum the original probabilities; The step of selecting the active subcarrier from the subcarrier set based on the probabilities of the index bit and the constellation symbol includes: The probabilities of the constellation symbols corresponding to all values ​​of each data symbol are sorted in descending order to obtain the sorting result; The active subcarrier is selected from the subcarrier set based on the index bit and the sorting result; wherein the number of active subcarriers corresponding to the probability of being sorted earlier is greater than the number of active subcarriers corresponding to the probability of being sorted later.

2. The index-based OTFS modulation method according to claim 1, characterized in that, The spread function of the time-delay-Doppler domain is: ； in, For the time-delay-Doppler domain extension function, For time-frequency domain time-varying transfer function, This represents the Doppler shift, where v It affects the time dimension of the time-frequency domain channel. This represents the frequency dimension of the channel in the time frequency domain. t For time, f For frequency.

3. An index-based OTFS modulation system, characterized in that, include: The bit stream segmentation module is used to divide the input bit stream at the transmitting end into multiple bit groups; each bit group includes index bits and symbol bits; An index modulation module is used to perform index modulation on multiple bit groups to obtain an index-modulated signal; the index-modulated signal includes index information for selecting active subcarriers through the index bits and constellation symbols modulated on the active subcarriers through the symbol bits; the number of active 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 active subcarriers; The first transformation module is used to perform ISFFT transformation on the index-modulated signal in the time-delay-Doppler domain to obtain a time-frequency domain signal; The second transformation module is used to perform a 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 that it can be received by the receiving end. The step of performing index modulation on multiple bit groups to obtain an index-modulated signal includes: Determine the number of index bits and the number of symbol bits in each bit group; The set of subcarriers available in the preset mapping table is determined based on the number of index bits; The symbol bits are mapped to data symbols, and the corresponding constellation symbols and their probabilities are determined based on the data symbols. The active subcarrier is selected from the set of subcarriers based on the probability of the index bit and the constellation symbol; The constellation symbols are mapped onto the active subcarriers to form the index-modulated signal; The probability of the constellation symbol is expressed as follows: ； in, For the first i The data symbol in the th k The constellation symbol in each bit group a j The conditional probability; It is the set of zodiac modulation symbols, that is, all possible zodiac symbols; A set of indices for constellation symbols. ; For the first i Each data symbol corresponds to a constellation symbol. a j The original probability; For all possible constellation symbols a j Sum the original probabilities; The step of selecting the active subcarrier from the subcarrier set based on the probabilities of the index bit and the constellation symbol includes: The probabilities of the constellation symbols corresponding to all values ​​of each data symbol are sorted in descending order to obtain the sorting result; The active subcarrier is selected from the subcarrier set based on the index bit and the sorting result; wherein the number of active subcarriers corresponding to the probability of being sorted earlier is greater than the number of active subcarriers corresponding to the probability of being sorted later.

4. An index-based OTFS communication system, characterized in that, The system includes the index-based OTFS modulation system of claim 3, and further includes 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.

5. The index-based OTFS communication system according to claim 4, characterized in that, The OTFS demodulation system includes: The third transformation module is used to perform Wigner transform on the time-domain signal to obtain the time-frequency domain signal; The fourth transformation module is used to perform SFFT transformation on the time-frequency domain signal to obtain the index-modulated signal in the time-delay-Doppler domain; An index demodulation module is used to perform index demodulation on the index-modulated signal to obtain multiple bit groups; A bit stream parallel streaming module is used to parallel stream multiple bit groups to obtain an output bit stream for the receiving end to receive.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the index-based OTFS modulation method as described in any one of claims 1 to 2.

7. 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, it implements the index-based OTFS modulation method as described in any one of claims 1 to 2.

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