A Multi-Mode In-Phase and Quadrature Index Modulation OTFS Communication System and Method

Abstract

The present invention provides a multi-mode in-phase quadrature index modulation OTFS communication system and method, which utilizes an index method of independently transmitting one-dimensional pulse amplitude modulation constellations by means of in-phase quadrature (IQ) components in a delay-Doppler domain (DD) sub-grid: First, at the transmitting end, the total transmitted bits are evenly divided into g groups, and then the bits in each group are evenly divided into two groups, which are independently transmitted on the I path and the Q path of the sub-grid respectively. The modulation processes on the I path and the Q path adopt a multi-mode index method, and different constellation modes are respectively adopted for modulation of each sub-grid by means of index bits; at the receiving end, an ML detection algorithm is adopted to respectively detect the index information and symbol information on the I path and the Q path of the sub-blocks to obtain the transmitted bits. The present invention extends multi-mode indexing to the IQ dimension and applies it to the OTFS index modulation system, solves the problem of low spectral efficiency caused by silent sub-grids in OTFS index modulation, and at the same time doubles the amount of information transmitted by the index, further improving the spectral efficiency of the system.

Description

Technical Field

[0001] The present invention belongs to the field of communication technologies, and particularly relates to a multi-mode in-phase quadrature index OTFS (Orthogonal Time Frequency Space) communication system and method, specifically involving in-phase quadrature dimension and multi-mode index modulation. Background Art

[0002] In high-speed mobile scenarios, the OTFS technology plays an important role. The addition of the index modulation technology further improves the stability of OTFS in high-speed mobile scenarios, but also brings the problem of low spectral efficiency. With the development of the information age, the demand for mobile bandwidth is increasing, and the problem of the spectral efficiency of the system has gradually emerged. The multi-mode index technology is used to completely eliminate the disadvantage of spectral utilization waste caused by silent sub-grids in the OTFS-IM (Orthogonal Time Frequency Space With Index Modulation) system. At the same time, the index domain is extended to the IQ (In-Phase and Quadrature) dimension, doubling the amount of information transmitted by the index and further improving the spectral efficiency of the system. Therefore, a multi-mode in-phase quadrature index modulation OTFS communication system is proposed. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to utilize the advantages of multi-mode index modulation to solve the problem of low spectral efficiency of the system caused by silent sub-grids in OTFS indexing. At the same time, the index domain is extended to the IQ dimension, doubling the amount of information transmitted by the index and further improving the spectral efficiency.

[0004] Technical Solution: A multi-mode in-phase quadrature index modulation OTFS communication system includes a transmitting end and a receiving end:

[0005] At the transmitting end, the total input bit stream is evenly divided into g groups, and then the bit stream of each group is evenly divided into two paths and independently transmitted on the I path and the Q path of the sub-grid. The modulation processes of the I path and the Q path adopt the multi-mode index method, and different constellation modes are used for modulation of each sub-grid by controlling with index bit information. Each group of modulated signals generates a DD domain signal through an OTFS block generator, and the DD domain signal is converted into a time-frequency domain signal through an inverse symplectic Fourier transform module. The time-frequency domain signal is converted into a time domain signal through a Heisenberg transform, and finally is sent to the channel for transmission through a CP and P / S module;

[0006] At the receiving end, first perform CP removal and S / P processing on the signal received from the channel. After processing, the signal is transformed by the Wigner transform to obtain a time-frequency domain signal. The time-frequency domain signal is then subjected to a symplectic Fourier transform to obtain a DD domain signal. The DD domain signal is re-divided into g groups, and then the I-channel and Q-channel of each sub-grid group are respectively subjected to ML detection to obtain the transmitted bits of each sub-grid group. Finally, the received end bit stream is obtained through a bit synthesizer.

[0007] Furthermore, the index bit information in the transmitting end is used to control the constellation mode adopted for modulation of each grid in the sub-grid group, and the constellation modes adopted by the grids in each group are different.

[0008] Furthermore, the transmitting end divides the bit stream into two groups, the I-channel and the Q-channel, for independent index modulation respectively, doubling the information transmitted by the index bits.

[0009] A multi-mode in-phase quadrature index modulation OTFS communication method includes the following steps:

[0010] Step 1: Divide the bit stream at the transmitting end into g groups, and then divide the bit stream in each group into the I-channel and the Q-channel for multi-mode indexing respectively. After modulation of each group is completed, a DD domain signal is generated through an OTFS block generation module;

[0011] Step 2: Perform an ISFFT transform on the DD domain signal to generate a time-frequency domain signal, then transform the signal to the time domain through a Heisenberg transform, and finally send the signal to the channel after passing through a CP and P / S module;

[0012] Step 3: First perform CP removal and S / P processing on the signal passing through the channel, then transform the signal into a time-frequency domain signal through a Wigner transform, and then transform the signal into a DD domain signal through an SFFT transform;

[0013] Step 4: Re-divide the DD domain signal into g groups. The grouped signal is divided into the I-channel and the Q-channel for ML detection respectively to obtain the detection signal of each sub-grid group at the receiving end, and the final complete transmitted bits are obtained using a bit synthesizer.

[0014] Furthermore, in the above Step 1, the size of the OTFS block output by the OTFS block generator in the OTFS block generation module is M×N. The A bits input at the transmitting end are equally divided into g groups, and each group consists of p bits. Among them, in the β (β∈{1,2,…,g})-th group, the p bits of the β group are evenly divided into two groups, denoted as p I and p Q , and the two-bit streams are independently transmitted on the I-channel and Q-channel of the sub-grid respectively. The I-channel and Q-channel are divided into index bits and constellation information bits In the I path The bits are index bit information, which is used to control the constellation patterns adopted by each sub - grid for signal modulation respectively, and the constellation patterns adopted by each grid in the sub - grid block are different, so as to solve the problem of low spectral efficiency caused by silent sub - grids in index modulation. And before index modulation, the bit stream is divided into two groups, the I path and the Q path, for independent index modulation respectively, doubling the information transmitted by the index bits and further improving the spectral efficiency of the system.

[0015] Furthermore, the number of types of constellation patterns adopted is equal to the number of grids n in the sub - grid block. The set of constellation patterns is represented as W = {1, 2, …, n}, and the index combination of the constellation pattern arrangement Information bits According to the constellation pattern corresponding to the index bit, perform corresponding traditional constellation modulation to generate the I - path sub - grid group signal Perform the same processing on the Q path to obtain Combine the I - path and Q - path index modulation signals together to obtain the β - th group of index modulation output signals Finally, combine the signals of each group through the OTFS block generator into an OTFS block of size M×N in the DD domain to obtain the output signal X after index modulation in the DD domain DD 。

[0016] Furthermore, in step 2, the transmitted symbols in the DD domain are converted to the time - frequency domain through the ISFFT transform, and then the time - domain OTFS signal is obtained through the Heisenberg transform:

[0017] Furthermore, in step 3, after passing through the CP - removing and S / P module, the time - domain received signal Y is obtained T , and then through another SFFT transform, the received signal in the DD domain is obtained

[0018] Furthermore, in step 4, the DD - domain signal is re - divided into g groups for detection. Each group of signals is divided into the I path and the Q path for ML detection respectively. In the I path, the detection of the β - th sub - grid group by the ML receiver can be expressed as: denotes taking the real part, H β = diag(H β ), and similarly, the Q path can be detected to obtain The detection result passes through the bit synthesizer to obtain the transmitted bits.

[0019] Beneficial effects: The present invention utilizes the advantages of multi-mode index modulation to solve the problems of low system spectrum utilization rate and spectrum waste caused by silent sub-grids in OTFS indexing. At the same time, the index domain is extended to the IQ dimension, doubling the amount of information transmitted by the index and further improving the spectrum utilization rate. The OTFS communication system based on multi-mode in-phase and quadrature index modulation can achieve better spectrum utilization rate and system performance than the traditional OTFS index modulation system. Description of the Drawings

[0020] Figure 1 FIG. is a transmission block diagram of an OTFS communication system based on multi-mode in-phase and quadrature index modulation according to the present invention;

[0021] Figure 2 FIG. is a constellation diagram of an OTFS communication system based on multi-mode in-phase and quadrature index modulation according to the present invention;

[0022] Figure 3 FIG. is a reception block diagram of an OTFS communication system based on multi-mode in-phase and quadrature index modulation according to the present invention. Detailed Embodiment

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0024] As Figure 1 shown, at the transmitting end, an A-bit bit stream is input, and the A bits are evenly divided into g groups by a bit splitter. The information p of each group i = A / g, i ∈ (1, 2,..., g). Further, the p i bits are divided into I-channel and Q-channel respectively for index modulation. Taking the I-channel of the β-th group as an example, is divided into two groups of bit streams bits and bits, where is the index bit, which is used to control which constellation mode is used for modulation in each grid of each sub-grid group. Its size can be expressed as bits are the constellation information bits, which are mapped to each grid in the sub-grid group according to the constellation mode corresponding to the index bit, and the constellation mode adopted in each grid is different. Therefore, the number of types of constellation modes is equal to the size n of the sub-grid group. Further, the set of constellation modes is denoted as W = {1, 2,..., n}, and the index combination of the constellation mode arrangement can be expressed as The sub-grid group performs corresponding constellation mode modulation on each internal sub-grid according to to generate the I-channel sub-grid group signal The same processing is performed on the Q-channel to obtain The I-channel and Q-channel index modulation signals are combined together to obtain the β-th group index modulation output signal Finally, the signals of each group are combined into an OTFS block of size M×N in the DD domain through the OTFS block generator to obtain the output signal X after the DD domain index modulation is completed. DD .

[0025] like Figure 2 As shown, taking the sub-grid size n=4 as an example, four constellation modes are used for index modulation, and the generated M-order one-dimensional PAM constellation diagram, compared with the OTFS-IM system, the constellation modulation and indexing method of the present invention makes it possible for there to be no silent sub-grids in the sub-grid group, thereby improving the spectrum utilization of the system. In the present invention, this constellation mode is used for index modulation for both the I path and the Q path.

[0026] like Figure 3 As shown, at the receiving end, after the signal passes through the channel and noise, the CP is removed at the receiving end to obtain the time domain received signal Y T , and then undergo another SFFT transformation to obtain the received signal in the DD domain According to the grouping method of the transmitter, the DD domain signals are re-divided into g groups for detection, and each group of signals is divided into I and Q channels for ML detection. Taking I channel as an example, the detection of the β-th sub-grid group of the ML receiver can be expressed as: represents the real part, H β =diag(H β ), and similarly, the Q path can be tested to obtain The detection result is passed through a bit synthesizer to obtain the transmission bit.

[0027] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A multi-mode in-phase quadrature index modulation OTFS communication system, characterized in that It includes a transmitter and a receiver: At the transmitting end, the input total bitstream is evenly divided into g groups, and then the bitstream of each group is evenly divided into two paths, which are independently transmitted on the I path and the Q path of the sub-grid respectively. The modulation processes of the I path and the Q path adopt the multi-mode indexing method, and the I path and the Q path are divided into index bits and constellation information bits In the I path The bits are index bit information, and each sub-grid is controlled by the index bit information to adopt different constellation modes for modulation. Each group of modulated signals passes through the OTFS block generator to generate a DD-domain signal. The DD-domain signal is converted into a time-frequency domain signal through the inverse symplectic Fourier transform module, and the time-frequency domain signal is converted into a time domain signal through the Heisenberg transform. Finally, it is sent to the channel for transmission after passing through the CP and P / S modules; At the receiver, first, the signal received from the channel is subjected to CP removal and S / P processing. The processed signal is transformed into a time-frequency domain signal through the Wigner transform. The time-frequency domain signal is then transformed into a DD domain signal through the symplectic Fourier transform. The DD domain signal is re-divided into g groups. Then, the I-channel and Q-channel of each sub-grid group are respectively subjected to ML detection to obtain the transmitted bits of each sub-grid group. Finally, the receiver bit stream is obtained through a bit synthesizer; At the receiving end, the DD-domain signal is re-divided into g groups for detection. Each group of signals is divided into the I-channel and the Q-channel respectively for ML detection. In the I-channel, the detection of the β-th sub-grid group of the ML receiver can be expressed as: denotes taking the real part, H β = diag(H β ), and similarly, the Q-channel can be detected to obtain The detection result passes through the bit synthesizer to obtain the transmitted bits, where is the signal of the I-channel sub-grid group.

2. The multi-mode in-phase quadrature index modulation OTFS communication system according to claim 1, characterized in that, The index bit information in the transmitter is used to control the constellation mode adopted for modulation of each grid in the sub-grid group, and the constellation modes adopted by the grids in each group are different.

3. The multi-mode in-phase quadrature index modulation OTFS communication system according to claim 1, wherein, The transmitter divides the bit stream into two groups, the I-channel and the Q-channel, for independent index modulation respectively, doubling the information transmitted by the index bits.

4. A multi-mode in-phase quadrature index modulation OTFS communication method, characterized in that It includes the following steps: Step 1: Divide the bitstream at the transmitting end into g groups, and then divide the bitstream in each group into I path and Q path respectively for multi-mode indexing. Divide the I path and Q path into index bits and constellation information bits In the I path The bits are index bit information. Each sub-grid is controlled by the index bit information to adopt different constellation modes for modulation. After the signals in each group are modulated, DD domain signals are generated through the OTFS block generation module; Step 2: Perform an ISFFT transform on the DD domain signal to generate a time-frequency domain signal, then transform the signal into the time domain through the Heisenberg transform, and finally send the signal to the channel after passing through the CP and P / S modules; Step 3: First, perform CP removal and S / P processing on the signal passing through the channel, then transform the signal into a time-frequency domain signal through the Wigner transform, and then transform the signal into a DD domain signal through the SFFT transform; Step 4: Re-divide the DD domain signal into g groups. The grouped signal is divided into the I-channel and the Q-channel for ML detection respectively to obtain the detection signals of each sub-grid group at the receiver, and the final complete transmitted bits are obtained using the bit synthesizer; In step 4, the DD domain signals are re-divided into g groups for detection. Each group of signals is divided into I channel and Q channel for ML detection respectively. In the I channel, the detection of the βth sub-grid group of the ML receiver can be expressed as: denotes taking the real part, H β = diag(H β ). Similarly, the Q channel can be detected to obtain The detection result passes through the bit synthesizer to obtain the transmitted bits, where is the signal of the I channel sub-grid group.

5. A multi-mode in-phase quadrature index modulation OTFS communication method according to claim 4, characterized in that In the said step 1, the size of the OTFS block output by the OTFS block generator in the OTFS block generation module is M×N. The A bits input by the transmitter are equally divided into g groups, and each group consists of p bits. Among them, in the β (β∈{1,2,…,g})-th group, the p bits of the β-th group are evenly divided into two groups, denoted as p I and p Q . The two-bit streams are independently transmitted on the I path and the Q path of the sub-grid respectively. In the I path, the index bit information is used to control the constellation mode adopted for signal modulation of each sub-grid, and the constellation mode adopted by each grid in the sub-grid block is different. The number of types of constellation modes adopted is equal to the number of grids n in the sub-grid block. The set of constellation modes is represented as W = {1,2,…,n}, and the index combination of the constellation mode arrangement α = 1,2,…,n, information bits According to the constellation mode corresponding to the index bit, perform corresponding traditional constellation modulation to generate the I-path sub-grid group signal Perform the same processing on the Q path to obtain Combine the I-path and Q-path index modulation signals together to obtain the β-th group index modulation output signal Finally, combine the signals of each group through the OTFS block generator into the OTFS block of size M×N in the DD domain to obtain the output signal X after the DD domain index modulation is completed DD .

6. A multi-mode in-phase orthogonal index modulation OTFS communication method according to claim 4, characterized in that In the said step 2, the transmitted symbols in the DD domain are converted to the time-frequency domain through the ISFFT transform, and then the time-domain OTFS signal is obtained through the Heisenberg transform:

7. A multi-mode in-phase quadrature index modulation OTFS communication method according to claim 4, characterized in that In step 3, after passing through the CP removal and S / P modules, the time-domain received signal Y is obtained T , and then through another SFFT transformation, the received signal in the DD domain is obtained

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