A method for increasing the degree of freedom of component indices in a two-dimensional orthogonal spatial dimension

Abstract

A method for increasing the degree of freedom of component index in two-dimensional orthogonal space dimensions, comprising the following steps: Step 1: Given the number of transmitting antennas at the transmitting end of a wireless communication system; Step 2: Obtain the zero-transmission space vector symbol of the transmitting antennas; Step 3: Separate the real part space and the imaginary part space in a zero-transmission vector symbol, and then splice the two together; Step 4: Set the number of component space index vectors to be modulated; Step 5: Obtain the calculation formula for the number of information bits carried by the component space index; Step 6: Activate the positions corresponding to the component index numbers in the zero-component index space vector with the assistance of the number of component index bits; Step 7: Modulate the components of the multi-dimensional signal constellation points to obtain the transmitting space vector and the total number of additional information bits it can carry. In the present invention, the number of transmitting antennas can be any value; the present invention expands the spatial degree of freedom of the components modulated in the constellation points, thereby improving the ability to carry additional information bits of the index bits.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communication, and particularly relates to a method for increasing the degree of freedom of component index in two-dimensional orthogonal space dimensions. Background Art

[0002] With the development in the past decade, taking the carrying of additional information as the research point, Space Modulation (IM) technology has become one of the key technologies for the next-generation wireless communication network. Initially, in 2008, Mesleh et al. proposed a Space Modulation (SM) scheme, using the antenna index in the spatial domain of the transmitting antenna to carry index information log2N t bits, where N t is the number of transmitting antennas. Subsequently, the proposed Generalized SM (GSM) scheme uses a combination of multiple antenna indices to increase the information bits carried by the antenna index n a is the number of active antennas. To further carry additional information, taking advantage of the combinability of multiple signal constellations and the variability of the number of active antennas, Cheng et al. proposed an Enhanced SM (ESM) scheme, Huang et al. proposed a GSM based on multi-index modulation (GSM-MIM) scheme, an Extended Space Index Modulation (ESIM), and a Signal Space Design based on the joint variability of multi-dimensional constellations and the number of active antennas (SSD-MCVA) scheme. The above index modulation technologies are limited to the one-dimensional spatial domain of the transmitting antenna, restricting the exploration of additional information.

[0003] Considering the orthogonality of components in a two-dimensional signal constellation, in 2015, Mesleh et al. proposed an Orthogonal Space Modulation (QSM) scheme. Since the QSM scheme exploits the orthogonal spatial domain of the transmitting antenna, compared with the SM scheme, the number of information bits of the antenna index it carries increases by log2N tIn this way, the one-dimensional antenna spatial domain is expanded into an orthogonal antenna spatial domain, that is, the transmit antenna index space is divided into the component index spaces of signal constellation points that are orthogonal and in-phase. Based on the orthogonal component space, by jointly designing the signal constellation and the number of active antennas in the orthogonal spatial domain, Huang et al. proposed a three-dimensional signal constellation-assisted orthogonal index modulation (QIM-TDC) scheme and an irregular Euclidean distance constellation design (IED-QIM) scheme in the orthogonal index modulation system, increasing the minimum Euclidean distance between transmit symbols, and thus improving the reliability of wireless communication. To further improve the ability to carry additional information, using the combinability of the symbol "j" and the multi-dimensional signal point components, the proposed spatial constellation design based on spatial modulation (SM-SC) scheme explores the symbol group index domain. Further, based on the SM-SC scheme, using the permutation method, the joint permutation, group, and antenna index-based spatial modulation (JPGA-ISM) developed the permutation index domain. However, in the SM-SC scheme and the JPGA-ISM scheme, the degree of freedom of the component index in the formed spatial symbols is still in the range of the number of transmit antennas. Therefore, the limitation of the degree of freedom of the component index restricts the ability to carry additional information of the antenna index bits. Summary of the Invention

[0004] The present invention provides a method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension. Instead of using the antenna index vector to modulate the signal constellation points, the component index vector is used to modulate the components in a multi-dimensional constellation point to the specified component index number, expanding the degree of freedom of the component index space in the constellation point to solve the defects in the prior art.

[0005] The present invention is realized through the following technical solutions:

[0006] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension includes the following steps:

[0007] Step 1: In a multiple-input multiple-output wireless communication system, given that the number of transmit antennas at the transmit end of the wireless communication system is N t ; N t ∈Z + and N t ≥2, Z + is a positive integer;

[0008] Step 2: The zero transmit space vector symbol of the transmit antenna is expressed as:

[0009] That is, a complex vector symbol of N t ×1 dimension where is the real part of the space vector, is the imaginary part of the space vector;

[0010] Step 3: To increase the spatial degrees of freedom of each component in the signal constellation points being modulated at specified positions in the component space, the real part space and the imaginary part space of a zero transmit space vector symbol are separated, and then the two are concatenated together to form a 2N t ×1 dimensional zero component index space vector S0;

[0011] Step 4: Set the components of the modulated N, N < 2N t dimensional signal constellation point s to m1, m2, …, m N , Z + is a positive integer, α ∈ {1, …, N}; the N components in the constellation point s: m1, m2, …, m N are modulated within the component index numbers 1, 2, …, 2N t range, and the spatial degrees of freedom of each component m β , β ∈ {1, 2, …, N} is γ CIM = 2N t - N + 1, which is equivalent to the positions of the idle component index positions and each component itself;

[0012] Step 5: The expression for the number of bits carrying the component space index information is That is Among the kinds of component index combinations,

[0013] kinds of combinations are legal, and the rest are illegal; With the assistance of the number of bits of the component space index information t specify a 2N λ ×1 dimensional component index vector V Activate the positions corresponding to the N component index numbers in the 2N t ×1 dimensional zero component index space vector S0 and set them to "1" to obtain a specified component position index vector

[0014] Step 7: The specified component position index vector specifies the N components of the constellation point s at the positions corresponding to the N component index numbers respectively to obtain the space vector S1. Through the splitting and combining operation, the transmit space vector X is obtained. At this time, the total number of additional information bits carried by the transmit space vector X is

[0015] A method for increasing the component index degrees of freedom in a two-dimensional orthogonal space dimension as described above. When the components of the signal constellation point are not modulated onto the active antennas in Step 4, the zero transmit space vector symbol is a zero space vector, that is, its respective components are: l ∈ {1, 2, …, N t}.

[0016] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension as described above. The calculation formula for the zero-component index space vector S0 in step three is:

[0017]

[0018] Thus, the component space index is extended from N t dimensions to 2N t dimensions.

[0019] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension as described above. In step five represents the number of combinations of component space indices. That is, in order to activate the positions corresponding to the N component index numbers in the zero-component index space vector S0 of 2N t ×1 dimension, there are possible cases.

[0020] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension as described above. The legal combinations of component indices form a component index vector set Γ = {V1, …, V τ}, and the dimension of each vector is 2N t ×1.

[0021] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension as described above. The space vector in step seven is expressed as where e i represents a 2N t ×1 dimensional unit vector with 1 at the i-th row position.

[0022] A method for increasing the degree of freedom of component index in a two-dimensional orthogonal space dimension as described above. The operation for obtaining the transmit space vector X in step seven is as follows: After modulating the N components in the signal constellation point s to the specified positions in the component space, in order to form a non-zero complex transmit space vector X, the components of vector S1 are split in half and re-combined. That is, its components S1(1), …, S1(N t ) are used as the real component space of vector X, and the components S1(N t +1), …, S1(2N t ) are used as the imaginary component space of vector X. Then the expression for the transmit space vector X is:

[0023]

[0024] The advantages of the present invention are as follows: In the present invention, the number of transmitting antennas does not need to satisfy a power of 2, and the number of transmitting antennas can be any value without restricting the number of transmitting antennas, which is convenient for use. At the same time, the present invention expands the spatial degrees of freedom of the components modulated in the constellation points, thereby improving the ability to carry additional information of the index bits and playing a role in improving the spectrum utilization rate. Moreover, under the condition of the same transmission rate, compared with the traditional design scheme, the present invention further increases the minimum Euclidean distance between the pairwise transmission space vectors, playing a role in enhancing the reliability of wireless communication. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 is the flowchart of the present invention;

[0027] Figure 2 is the schematic diagram of the free space of the real part and the imaginary part of the present invention. Detailed Embodiment

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0029] As Figure 1 shown, a method for increasing the index freedom of components in two-dimensional orthogonal space dimensions includes the following steps:

[0030] Step 1: In a multiple-input multiple-output (MIMO) wireless communication system, given that the number of transmitting antennas at the transmitting end of the wireless communication system is N t ; N t ∈Z + and N t ≥2, Z + is a positive integer;

[0031] Step 2: The zero transmission space vector symbol of the transmitting antenna is represented as: That is, a complex vector symbol of an N t ×1 dimension where is the real part of the space vector, and is the imaginary part of the space vector;

[0032] Step 3: To increase the spatial degrees of freedom for each component in the signal constellation points to be modulated at the specified positions in the component space, separate the real part space and the imaginary part space of a zero transmission space vector symbol, and then splice the two together to form a 2N t ×1 - dimensional zero - component index space vector S0;

[0033] Step 4: Set the components of the N, N < 2N t - dimensional signal constellation point s to be m1, m2, …, m N , Z + is a positive integer, α ∈ {1, …, N}; the N components in the constellation point s: m1, m2, …, m N are modulated within the component index numbers 1, 2, …, 2N t range. As shown in Figure 2 , for each component m β , β ∈ {1, 2, …, N}, the spatial degree of freedom of the component space is γ CIM = 2N t - N + 1, which is equivalent to the positions of the idle component index positions and each component itself;

[0034] Step 5: The expression for the number of bits carrying the component space index information is That is Among the component index combinations,

[0035] combinations are legal, and the rest are illegal. With the assistance of the number of bits of the component space index information t λ , specify a 2N t ×1 - dimensional component index vector V

[0036] Step 7: The specified component position index vector assigns the N components of the constellation point s to the positions corresponding to the N component index numbers respectively to obtain the space vector S1. Through the splitting and combining operation, the transmitted space vector X is obtained. At this time, the total number of additional information bits carried by the transmitted space vector X is

[0037] Specifically, in step four of this embodiment, when the components of the signal constellation points are not modulated onto the active antennas, the zero transmit space vector symbol is a zero space vector, that is, its respective components are: e ∈ {1, 2, …, N t}.

[0038] Specifically, as Figure 2 shown, the calculation formula for the zero component index space vector S0 in step three of this embodiment is:

[0039]

[0040] Thus, the component space index is extended from N t dimensions to 2N t dimensions.

[0041] More specifically, in step five of this embodiment represents the number of component space index combinations, that is, in order to activate the positions corresponding to the N component index numbers in the 2N t ×1 dimensional zero component index space vector S0, there are possible cases. Compared with the traditional space modulation technology scheme, the proposed technology scheme has certain advantages in the degrees of freedom of the component space, and the number of transmit antennas does not need to satisfy the power of 2. For example: the QSM scheme, which not only requires the number of transmit antennas to satisfy the power of 2, but also the degrees of freedom of the component space is only γ QSM = N t ; the degrees of freedom of the component space of the SM-SC scheme is also only γ SM-SC = N t .

[0042] Furthermore, the legal component index combinations in step five of this embodiment form a component index vector set Γ = {V1, …, V τ}, the dimension of each vector is 2N t ×1. Compared with the QSM and SM-SC schemes carrying additional information, the proposed design method significantly improves the ability to carry additional information.

[0043] Even further, the transmit space vector in step seven of this embodiment is expressed as where e i represents a 2N t ×1 dimensional unit vector with 1 at the i-th row position.

[0044] Further, the operation of obtaining the transmission space vector X in Step 7 of this embodiment is as follows: After modulating N components in the signal constellation point s to specified positions in the component space, in order to form a non-zero complex transmission space vector X, the components in the vector S1 are split in half and recombined, that is, its components S1(1), …, S1(N t ) are used as the real part component space of the vector X, and the components S1(N t +1), …, S1(2N t ) are used as the imaginary part component space of the vector X. Then, the expression of the transmission space vector X is:

[0045]

[0046] Embodiment

[0047] Step 1: In a multiple-input multiple-output wireless communication system, the number of transmit antennas at the transmitter of the given wireless communication system is N t ; N t ∈Z + and N t ≥2, Z + is a positive integer;

[0048] Step 2: The zero emission space vector symbol of the transmitting antenna is represented as: That is, a complex vector symbol of N t ×1 dimension where is the real part of the space vector, is the imaginary part of the space vector;

[0049] Step 3: In order to increase the spatial degrees of freedom for each component in the signal constellation point to be modulated at the specified position in the component space, the real part space and the imaginary part space in a zero transmission space vector symbol are separated, and then, the two are spliced together to form a zero component index space vector S0 of 2N t ×1 dimension. The calculation formula of the zero component index space vector S0 is:

[0050]

[0051] Thus, the component space index is extended from N t dimension to 2N t dimension.

[0052] Step 4: Set the components of the modulated N, N < 2N t dimensional signal constellation point s to m1, m2, …, m N , Z + is a positive integer, α ∈ {1, …, N}; The N components in the constellation point s: m1, m2, …, m NModulation is carried out within the component index numbers 1, 2, …, 2N t as shown in Figure 1 Each component m β , where β ∈ {1, 2, …, N}, has a component space degree of freedom γ CIM = 2N t - N + 1, which is equivalent to the positions of the idle component index positions and each component itself;

[0053] When the components of the signal constellation points are not modulated onto the active antennas, the zero transmission space vector symbol is a zero space vector, that is, its respective components are: e ∈ {1, 2, …, N t};

[0054] Step Five: The expression for the number of bits carrying the component space index information is (where represents the number of combinations of component space indices, that is, in order to activate the positions corresponding to the N component index numbers in the 2N t ×1 - dimensional zero - component index space vector S0, there are possible cases), that is Among the component index combinations, combinations are legal, and the rest are illegal. The legal combinations of component indices form a component index vector set Γ = {V1, …, V τ}, The dimension of each vector is 2N t ×1;

[0055] Step Six: With the assistance of the number of bits of the component space index information , a 2N t ×1 - dimensional component index vector V λ is specified, The positions corresponding to the N component index numbers in the 2N t ×1 - dimensional zero - component index space vector S0 are activated and set to "1" to obtain a specified component position index vector

[0056] Step Seven: The specified component position index vector assigns the N components of the constellation point s to the positions corresponding to the N component index numbers respectively, obtaining a space vector s1, expressed as Here, e i represents a 2N tThe ×1 dimensional unit vector, and the operation of obtaining the transmission space vector X is as follows: After modulating N components in the signal constellation points to the specified positions in the component space, in order to form a non-zero complex transmission space vector X, the components in the vector S1 are split in half and recombined, that is, its components S1(1), …, S1(N t ) are used as the real part component space of the vector X, and the components S1(N t +1), …, S1(2N t ) are used as the imaginary part component space of the vector X. Then the expression of the transmission space vector X is:

[0057]

[0058] Meanwhile, the total number of additional information bits carried by the transmission space vector X is

[0059] The comparison of the additional information carried by the embodiments and the comparative example by using the method of the embodiment and the space constellation design based on space modulation (SM-SC) scheme (i.e., the comparative example) under the condition that the number of transmitting antennas and the number of components are the same is shown in Table 1 (where I AI represents the additional information bit, and N is the number of components in the modulated signal constellation point):

[0060]

[0061]

[0062] Table 1

[0063] It can be seen from the data in Table 1 that the embodiments of the present invention greatly improve the ability to carry additional information compared with the comparative example, thereby effectively improving the spectrum utilization rate, that is, improving the transmission rate. For example: The transmission rates of the embodiments of the invention and the comparative example can be respectively expressed by the mathematical formulas Here and are the information bits carried by the constellation points, and are the additional information bits transmitted. When the same constellation is used, However, since the embodiments of the invention improve the carrying of additional information, so R1≥R2.

[0064] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the 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 invention.

Claims

1. A method for increasing the freedom of component indexing in a two-dimensional orthogonal space dimension, characterized in that: The steps include: Step 1: In a wireless communication system, the number of transmitting antennas at the transmitting end of a given wireless communication system is N t ; N t ∈Z + And N t ≥2, Z + is a positive integer; Step 2: The zero transmit space vector symbol of the transmitting antenna is represented as: That is, an N t ×1-dimensional complex vector symbol in is the real part of the space vector, is the imaginary part of the space vector; Step 3: Separate the real and imaginary parts of a zero-emission space vector symbol, and then splice the two together to form a 2N t ×1-dimensional zero-component index space vector S0; Step 4: Set the modulated N, N < 2N t The components of the dimensional signal constellation point s are m1, m2, ..., m N , Z + is a positive integer, α∈{1,…,N}; N components in the constellation point s: m1, m2,…, m N Can be modulated on component index 1, 2, ..., 2N t Within the range, each component m β , the component space degrees of freedom of β∈{1,2,…,N} is γ CIM =2N t -N+1; Step 5: The expression for the number of bits carrying the component space index information is Right now Component index combination The combinations are legal, the rest are illegal; Step 6: Index information bits in component space With assistance, specify a 2N t ×1-dimensional component index vector V λ , 2N t The positions corresponding to the N component index numbers in the zero component index space vector S0 of the ×1 dimension are activated and set to "1", obtaining a specified component position index vector Step 7: The specified component position index vector The N components of the constellation point s are assigned to the positions corresponding to the N component index numbers to obtain the space vector S1. Through the splitting and combining operations, the transmission space vector X is obtained. At the same time, the total number of additional information bits that the transmission space vector X can carry is The operation of obtaining the emission space vector X through the splitting and combining operation is as follows: split the components of vector S1 in half and recombine them, that is, its components S1(1),…,S1(N t ) as the real component space of vector X, S1(N t +1),…,S1(2N t ) component as the imaginary component space of vector X, then the expression of the emission space vector X is:

2. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: In the step 4, when the components of the signal constellation point are not modulated onto the activated antenna, the zero transmission space vector symbol is a zero space vector, that is, its components are:

3. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: The calculation formula of the zero component index space vector S0 in step 3 is: So as to realize the component space index from N t Dimension expansion to 2N t dimension.

4. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: In step five Represents the number of component space index combinations, that is, in order to convert 2N t ×1-dimensional zero-component index space vector S0 corresponding to the N component index numbers in the position activation, then possible situations.

5. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: The legal step in step 5 The component index combination forms a component index vector set The dimension of each vector is 2N t ×1.

6. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: The space vector S1 in step 7 can be expressed as Here i Represents a 2N with 1 at position 1 in row i t ×1-dimensional unit vector.

7. The method for increasing the degree of freedom of component indexing in a two-dimensional orthogonal space dimension according to claim 1, characterized in that: The transmission space vector X acquisition operation in step 7 is as follows: after modulating the N components in the signal constellation point s to the specified position in the component space, in order to form a non-zero complex transmission space vector X, the components in the vector S1 are split in half and recombined, that is, its components S1(1),…,S1(N t ) as the real component space of vector X, S1(N t +1),…,S1(2N t ) component as the imaginary component space of vector X, then the expression of the emission space vector X is:

Images