CN112616120B - NOMA transmission system and method of convex mirror antenna array - Google Patents
NOMA transmission system and method of convex mirror antenna array Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/046—Wireless resource allocation based on the type of the allocated resource the resource being in the space domain, e.g. beams
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/0473—Wireless resource allocation based on the type of the allocated resource the resource being transmission power
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
Abstract
The invention discloses a NOMA transmission system and method of a convex mirror antenna array. The wave beam selection network acquires a channel between a user antenna and a convex mirror antenna array, determines a wave beam space channel of a user according to the channel between the user antenna and the convex mirror antenna array, and performs wave beam selection and power distribution operation according to the wave beam space channel of the user to obtain a selected wave beam and user distribution power. By adopting the system and the method, the convex mirror antenna array and the NOMA transmission principle are utilized, a plurality of users are supported, and only one RF link is used, so that the complexity and the cost of system hardware are reduced; by utilizing the sparsity of the millimeter wave channel, the beam selection is simply and effectively realized, the complexity is reduced, and the total transmission rate is effectively improved.
Description
Technical Field
The invention relates to the technical field of mobile communication, in particular to a NOMA transmission system and method of a convex mirror antenna array.
Background
As the demand for bandwidth of mobile communication systems is higher and higher, and the spectrum of low frequency band is distributed and used, the development of millimeter wave band is trending. The transmission loss of the wireless electromagnetic wave in the millimeter wave band is large, and a large-scale antenna array needs to be used for compensation through a beam forming technology. The lens antenna array has high integration level and flexible and convenient use, and is a common mode for realizing large-scale antenna arrays. The Non-orthogonal multiple access (NOMA) technology can access more users under the same hardware condition, and has a wide application prospect in millimeter wave communication by combining with a lens antenna array.
In the existing millimeter wave lens antenna array communication system, the number of RF links is the same as the number of users, and the hardware cost is very high in a large-scale access scene; or the number of users supported by the given number of RF links is small, and the requirement of large-scale access cannot be met. In existing schemes used in conjunction with NOMA technology, users of the same NOMA group are required to share the same beam, yet with higher hardware complexity and cost.
Disclosure of Invention
The invention aims to provide a NOMA transmission system and method of a convex mirror antenna array, which can realize that users using different beams form NOMA groups and use the same RF link.
In order to achieve the purpose, the invention provides the following scheme:
a convex mirror antenna array NOMA transmission system, comprising:
the system comprises a channel estimation module, a NOMA superposition coding module, a digital-to-analog conversion module, an RF link, a beam selection network and a convex mirror antenna array;
the channel estimation module is used for estimating a beam space channel of a user;
the channel estimation module is connected with the beam selection network, and the beam selection network is used for carrying out beam selection and power distribution operation according to the beam space channel of the user to obtain a selected beam and user distribution power;
the beam selection network is connected with the NOMA superposition coding module, and the NOMA superposition coding module is used for carrying out superposition coding operation according to the user distributed power to obtain a digital baseband signal;
the digital-to-analog conversion module is connected with the NOMA superposition coding module and is used for converting the digital baseband signals into analog baseband signals;
the RF link is connected with the digital-to-analog conversion module and is used for converting the analog baseband signal into a radio frequency signal;
the beam selection network is connected to the RF link, and the beam selection network is configured to feed the radio frequency signal onto the selected beam;
the convex mirror antenna array is connected with the beam selection network and is used for transmitting radio frequency signals fed by the beam selection network.
Optionally, the beam selection network specifically includes:
a plurality of phase shifters; the phase shifter is a 1-bit phase shifter;
each phase shifter is connected with the antennas of the convex mirror antenna array in a one-to-one correspondence mode;
the state of the phase shifter is 0 or 1; when the state of the phase shifter is 0, the antenna connected with the phase shifter is not selected; and when the state of the phase shifter is 1, the antenna connected with the phase shifter is selected.
Optionally, the method further includes:
a user receiving module;
the user receiving module is wirelessly connected with the convex mirror antenna array and is used for receiving the radio frequency signals transmitted by the convex mirror antenna array, processing the received signals and then outputting the data information of the user.
The invention also provides a NOMA transmission method of the convex mirror antenna array, which comprises the following steps:
acquiring a channel between a user antenna and a convex mirror antenna array;
determining a beam space channel of a user according to a channel between the user antenna and the convex mirror antenna array;
carrying out beam selection and power distribution operation according to the beam space channel of the user to obtain a selected beam and user distribution power;
and carrying out signal transmission according to the selected wave beam and the user distributed power.
Optionally, the determining a beam space channel of the user according to the channel between the user antenna and the convex mirror antenna array specifically includes:
and determining the beam space channel of the user by adopting the following formula according to the channel between the user antenna and the convex mirror antenna array:
wherein the content of the first and second substances,
U＝[a(θ1),a(θ2),…,a(θN)]H
J(N)＝{i-(N-1)/2,i＝0,1,…,N-1}
in the formula (I), the compound is shown in the specification,
beam space channel, h, for a userkFor the channel between the user antenna and the convex mirror antenna array, U is the beam space transformation matrix, a (theta) is the array corresponding vector of the spatial direction angle theta, thetaNIs the nth spatial direction angle, N is the number of antennas in the convex mirror antenna array, j (N) is a set of antenna serial numbers, i is the antenna serial number, and N is the offset antenna serial number.
Optionally, the performing the beam selection and power allocation operation according to the beam space channel of the user to obtain the selected beam and the user allocated power specifically includes:
comparing the gain of all beam space channels of the user, and determining the beam corresponding to the maximum gain as the selected beam of the user;
generating an active beam set according to the selected beams of all the users;
determining a selectable beam set from the active beam set; the intersection of the selectable beam set and the active beam set is an empty set, and the union of the selectable beam set and the active beam set is a set formed by all beams which can be used by the convex mirror antenna array;
determining a corresponding sum rate of the active beam set; the sum rate is the sum of the data rates of all users;
adding each beam of the selectable beam set into the active beam set respectively to obtain a reconstructed active beam set; the number of the reconstructed active beam sets is equal to the number of the elements in the selectable beam sets;
determining and comparing the corresponding sum rates of all the reconstructed activation beam sets to obtain the maximum sum rate;
judging whether the maximum sum rate is greater than the sum rate corresponding to the active beam set; if so, determining the reconstructed beam set corresponding to the maximum sum rate as an updated active beam set, and returning to the step of determining the sum rate corresponding to the active beam set; if not, determining all selected beams in the activated beam set as selected beams;
and determining the user distribution power according to the selected wave beam.
Optionally, the method for calculating the sum rate specifically includes:
summing the gains of all beam space channels of the user to obtain an effective channel coefficient of the user;
the power gains of the effective channel coefficients of all the users are arranged in a descending order, and the data rate lower limit values of all the users except the user corresponding to the maximum power gain are obtained;
determining the data rate of the user corresponding to the maximum power gain according to the power gain of the effective channel coefficient of the user and the data rate lower limit value;
and summing the data rate of the user corresponding to the maximum power gain and the data rate lower limit values of all the users except the user corresponding to the maximum power gain to obtain a sum rate.
Optionally, the determining the data rate of the user corresponding to the maximum power gain according to the power gain of the effective channel coefficient of the user and the data rate lower limit specifically includes:
acquiring the sum of the powers;
according to the power gain of the effective channel coefficient of the user and the data rate lower limit value, performing power distribution on the user corresponding to the minimum power gain to obtain first user distribution power;
according to the power sum, the first user distribution power, the power gain of the effective channel coefficient of the user and the data rate lower limit value, performing power distribution on all users except the user corresponding to the maximum power gain and the minimum power gain to obtain a plurality of user distribution powers;
subtracting the sum of the power from the sum of the first user distributed power and the plurality of user distributed powers to obtain the distributed power of the user corresponding to the maximum power gain;
and determining the data rate of the user corresponding to the maximum power gain according to the distributed power of the user corresponding to the maximum power gain and the maximum power gain.
Alternatively to this, the first and second parts may,
the performing power distribution on the user corresponding to the minimum power gain according to the power gain of the effective channel coefficient of the user and the data rate lower limit value to obtain first user distributed power specifically includes:
determining the first user allocated power according to the following formula:
in the formula, pKAllocating power, R, to a first userKLower limit value of data rate for user corresponding to minimum power gain, PtotIs the sum of powers, σ2For noise power, a 'is the active beam set, | a' | is the total number of elements in the active beam set, K is the user serial number corresponding to the minimum power gain,
the power gain for the effective channel coefficient with user number K,
the effective channel coefficient with the user serial number of K;
the allocating power to all users except the user corresponding to the maximum power gain and the minimum power gain according to the power sum, the first user allocated power, the power gain of the effective channel coefficient of the user, and the data rate lower limit value, to obtain a plurality of user allocated powers, specifically including:
determining the distributed power of any user except the user corresponding to the maximum power gain and the minimum power gain according to the following formula:
in the formula, pkDistributing power for users with user serial number k, k being user serial number except the user corresponding to maximum power gain and minimum power gain, RkThe data rate lower limit value of a user with a user serial number k, m is a user serial number variable, pmAllocating power to the user with the user serial number m,
the power gain for the effective channel coefficient with user number k,
the effective channel coefficient with the user serial number k;
the determining the data rate of the user corresponding to the maximum power gain according to the distributed power of the user corresponding to the maximum power gain and the maximum power gain specifically includes:
determining the data rate of the user corresponding to the maximum power gain according to the following formula:
wherein the content of the first and second substances,
in the formula, R1Data rate, p, of the user corresponding to maximum power gain1The allocated power for the user corresponding to the maximum power gain,
for the maximum power gain, the gain is,
the effective channel coefficient of the user corresponding to the maximum power gain.
Optionally, the performing signal transmission according to the selected beam and the user allocated power specifically includes:
performing superposition coding operation according to the user distributed power to obtain a digital baseband signal;
converting the digital baseband signal to an analog baseband signal;
converting the analog baseband signal to a radio frequency signal;
feeding the radio frequency signal onto the selected beam;
transmitting the radio frequency signal fed onto the selected beam;
wherein the content of the first and second substances,
the performing superposition coding operation according to the user allocated power to obtain a digital baseband signal specifically includes:
performing superposition coding operation according to the following formula to obtain a digital baseband signal:
where x is the digital baseband signal, skFor user data with user number k, pkAnd allocating power to the user with the user serial number k.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a NOMA transmission system and method of a convex mirror antenna array.A wave beam selection network acquires a channel between a user antenna and the convex mirror antenna array, determines a wave beam space channel of a user according to the channel between the user antenna and the convex mirror antenna array, and performs wave beam selection and power distribution operation according to the wave beam space channel of the user to obtain a selected wave beam and user distribution power. The invention utilizes the convex mirror antenna array and NOMA transmission principle, only uses one RF link while supporting a plurality of users, thus reducing the complexity and cost of system hardware; by utilizing the sparsity of the millimeter wave channel, the beam selection is simply and effectively realized, the complexity is reduced, and the total transmission rate is effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a diagram of a convex mirror antenna array NOMA transmission system in the embodiment of the present invention;
FIG. 2 is a flow chart of a method for NOMA transmission using a convex mirror antenna array in accordance with an embodiment of the present invention;
fig. 3 is a flow chart of a beam selection method according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a NOMA transmission system and method of a convex mirror antenna array, which can realize that users using different beams form NOMA groups and use the same RF link.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Examples
Fig. 1 is a structural diagram of a convex mirror antenna array NOMA transmission system in the embodiment of the present invention, and as shown in fig. 1, a convex mirror antenna array NOMA transmission system includes:
the system comprises a channel estimation module, a NOMA superposition coding module, a digital-to-analog conversion module, an RF link, a beam selection network, a convex mirror antenna array and a user receiving module.
The channel estimation module is used for estimating beam space channels of users. Transmitting end using convex mirror antenna array, hkIs an N-dimensional vector representing a channel between the lens antenna array and the antenna of the user k, and N represents the number of the antennas in the lens antenna array;
is the beam space channel for user k, U represents the beam space transformation matrix:
U＝[a(θ1),a(θ2),…,a(θN)]H
wherein the content of the first and second substances,
J(N)＝{i-(N-1)/2,i＝0,1,…,N-1}
a (θ) is the array corresponding vector of N uniformly distributed spatial directions; in the system of fig. 1, each antenna corresponds to a beam in one of the above-mentioned spatial directions. Channel estimation module obtains beam space channel of user
k＝1,2,…,K。
The channel estimation module is connected with a beam selection network, and the beam selection network is used for carrying out beam selection and power distribution operation according to a beam space channel of a user to obtain a selected beam and user distribution power.
The beam selection network is connected with the NOMA superposition coding module, and the NOMA superposition coding module is used for carrying out superposition coding operation according to the power distributed by the user to obtain a digital baseband signal.
The digital-to-analog conversion module is connected with the NOMA superposition coding module and is used for converting the digital baseband signals into analog baseband signals.
The RF link is connected with the digital-to-analog conversion module and is used for converting the analog baseband signal into a radio frequency signal.
A beam selection network is connected to the RF link for feeding radio frequency signals onto the selected beam. The beam selection network forms the beam selection network with N1-bit phase shifters, where each phase shifter has three states, namely "+ 1(0 degree phase)", "-1 (180 degree phase)", and "0 (off state)". Only two states, i.e., "+ 1(0 degree phase)" and "0 (off state)", are used in the present invention. Each phase shifter is connected with one antenna, and when the phase shifter state is + 1', the antenna/wave beam connected with the phase shifter is selected; when the phase shifter state is "0 (off state)", it indicates that the antenna/beam connected to the phase shifter is not used.
The convex mirror antenna array is connected with the beam selection network and is used for transmitting radio frequency signals fed by the beam selection network. The convex mirror antenna array is composed of N power amplifiers, N antennas arranged on a focusing arc and an electromagnetic lens, and converts a radio-frequency signal fed to a certain antenna into electromagnetic waves in a specific direction to radiate the electromagnetic waves.
The user receiving module is in wireless connection with the convex mirror antenna array and is used for receiving the radio-frequency signals transmitted by the convex mirror antenna array, processing the received signals and then outputting data information of a user. Each user receiving module comprises a receiving antenna, an RF link, an analog-to-digital converter, an SIC decoder and the like, and the user receiving modules respectively output a code stream of one user.
The connection mode in the convex mirror antenna array NOMA transmission system is as follows:
the NOMA superposition coding module and the digital-to-analog conversion module are connected through a network;
the digital-to-analog conversion module is electrically connected with the RF link;
the RF link is electrically connected with the beam selection network;
the beam selection network is electrically connected with the convex mirror antenna array;
the convex mirror antenna array is wirelessly connected with the user receiving module.
Fig. 2 is a flow chart of a method for transmitting a convex mirror antenna array NOMA in an embodiment of the present invention. As shown in fig. 2, a method for NOMA transmission by a convex mirror antenna array includes:
step 101: a channel between a user antenna and a convex mirror antenna array is acquired.
Step 102: the beam space channel of the user is determined from the channel between the user antenna and the array of convex mirror antennas.
Step 103: and carrying out beam selection and power distribution operation according to the beam space channel of the user to obtain the selected beam and the user distributed power.
Step 104: and transmitting signals according to the selected wave beams and the user distributed power.
Wherein the content of the first and second substances,
according to the channel between the user antenna and the convex mirror antenna array, determining the beam space channel of the user by adopting the following formula:
wherein the content of the first and second substances,
U＝[a(θ1),a(θ2),…,a(θN)]H
J(N)＝{i-(N-1)/2,i＝0,1,…,N-1}
in the formula (I), the compound is shown in the specification,
beam space channel, h, for a userkFor user antennas and convex mirror antenna arraysU is a beam space transformation matrix, a (theta) is an array corresponding vector of a space direction angle theta, thetaNIs the nth spatial direction angle, N is the number of antennas in the convex mirror antenna array, j (N) is a set of antenna serial numbers, i is the antenna serial number, and N is the offset antenna serial number.
1) and comparing the gain of all beam space channels of the user, and determining the beam corresponding to the maximum gain as the selected beam of the user.
The beam selection network obtains the channel gain of each user on each beam from the channel estimation module
K is 1,2, …, K is the user number, j is 1,2, …, N is the beam number;
the beam selection network selects an optimal beam j for user k*The wave beam j*Corresponding to the maximum channel power gain of user k, i.e.
Wherein
Is the channel gain of user k on beam j.
2) And generating the activation beam set according to the selected beams of all the users.
Forming a beam set by the optimal beams of K users, and excluding repeated beams to form a beam set A; the active beam set output by the MAX selection method is a.
3) Determining a selectable beam set from the active beam set; the intersection of the selectable beam set and the active beam set is an empty set, and the union of the selectable beam set and the active beam set is a set formed by all beams which can be used by the convex mirror antenna array.
4) Determining the corresponding sum rate of the activation beam set; the sum rate is the sum of the data rates of all users.
5) Adding each wave beam of the selectable wave beam set into the activated wave beam set respectively to obtain a reconstructed activated wave beam set; the number of reconstructed active beam sets is equal to the number of elements in the selectable beam set.
6) And determining and comparing the corresponding sum rates of all the reconstructed active beam sets to obtain the maximum sum rate.
7) Judging whether the maximum sum rate is greater than the sum rate corresponding to the active beam set; if yes, determining the reconstructed beam set corresponding to the maximum sum rate as the updated active beam set, and returning to the step 4); if not, all selected beams in the active beam set are determined as the selected beams.
8) And determining the user distributed power according to the selected wave beam.
Wherein the content of the first and second substances,
the calculating method of the sum rate specifically comprises the following steps:
1.1) summing the gains of all beam space channels of the user to obtain an effective channel coefficient of the user;
1.2) performing descending order arrangement on the power gains of the effective channel coefficients of all users to obtain the data rate lower limit values of all users except the user corresponding to the maximum power gain;
1.3) determining the data rate of the user corresponding to the maximum power gain according to the power gain of the effective channel coefficient of the user and the lower limit value of the data rate;
1.4) summing the data rate of the user corresponding to the maximum power gain and the data rate lower limit values of all the users except the user corresponding to the maximum power gain to obtain a sum rate.
Wherein, 1.3) specifically includes:
1.3.1) obtaining the power sum.
1.3.2) according to the power gain of the effective channel coefficient of the user and the lower limit value of the data rate, carrying out power distribution on the user corresponding to the minimum power gain to obtain the first user distributed power.
Determining a first user allocated power according to the following formula:
in the formula, pKAllocating power, R, to a first userKLower limit value of data rate for user corresponding to minimum power gain, PtotIs the sum of powers, σ2For noise power, a 'is the active beam set, | a' | is the total number of elements in the active beam set, K is the user serial number corresponding to the minimum power gain,
the power gain for the effective channel coefficient with user number K,
the effective channel coefficient with the user serial number of K.
1.3.3) according to the power sum, the first user distribution power, the power gain of the effective channel coefficient of the user and the data rate lower limit value, carrying out power distribution on all users except the user corresponding to the maximum power gain and the minimum power gain to obtain a plurality of user distribution powers.
Determining the distributed power of any user except the user corresponding to the maximum power gain and the minimum power gain according to the following formula:
in the formula, pkDistributing power for users with user serial number k, k being user serial number except the user corresponding to maximum power gain and minimum power gain, RkThe data rate lower limit value of a user with a user serial number k, m is a user serial number variable, pmAllocating power to the user with the user serial number m,
the power gain for the effective channel coefficient with user number k,
is the effective channel coefficient with the user serial number k.
1.3.4) the power sum is differenced with the sum of the first user distributed power and the distributed power of a plurality of users, and the distributed power of the user corresponding to the maximum power gain is obtained.
1.3.5) determining the data rate of the user corresponding to the maximum power gain according to the distributed power of the user corresponding to the maximum power gain and the maximum power gain.
Determining the data rate of the user corresponding to the maximum power gain according to the following formula:
wherein the content of the first and second substances,
in the formula, R1Data rate, p, of the user corresponding to maximum power gain1The allocated power for the user corresponding to the maximum power gain,
for the maximum power gain, the gain is,
the effective channel coefficient of the user corresponding to the maximum power gain.
A) and performing superposition coding operation according to the user distributed power to obtain a digital baseband signal.
Performing superposition coding operation according to the following formula to obtain a digital baseband signal:
where x is the digital baseband signal, skThe user data with user serial number k.
B) The digital baseband signal is converted to an analog baseband signal.
C) The analog baseband signal is converted to a radio frequency signal.
D) A radio frequency signal is fed onto the selected beam.
E) Transmitting the radio frequency signal fed onto the selected beam.
Specifically, as shown in fig. 3, fig. 3 is a flowchart of a beam selection method provided in the embodiment of the present invention, and the beam selection method of the beam selection network is as follows:
defining: the active beam set a is a set of beam formations selected by the beam selection network; the selectable beam set B is a beam set, and the beam selection network selects a beam from the beam set and adds the selected beam into the active beam set; the selectable beam set B does not intersect the active beam set a, and the union of B and a is 1,2, …, N, i.e., the set of all beams.
Step 1: initializing the selectable beam set as B ═ {1, 2, …, N }, and activating the beam set as A ═ Φ;
step 2: selecting beams by using a maximum gain beam selection method to form an active beam set A; updating the selectable beam set to be B-A;
and step 3: for each beam B in the selectable beam set B, the following operations are performed in turn:
(S3-1) assuming that the beam b is added to the active beam set a, constituting an active beam set a';
(S3-2) determining the SIC coding order of the user: the sum of the channel coefficients of user k on each beam in the active set of beams is the effective channel coefficient of the user, i.e. the sum of the channel coefficients on each beam in the active set of beams is the effective channel coefficient of the user k
Wherein, | a '| represents the number of elements in the set a'. The K users are arranged in descending order of the power gain of the effective channel coefficient, i.e.
Then the decoding order of the NOMA group formed by K users is that the user (the user with the smallest power gain of the effective channel coefficient, namely the K-th user) arranged at the last is decoded first, and the user (the user with the largest power gain of the effective channel coefficient, namely the 1 st user) arranged at the first is decoded last;
(S3-3) allocating Power to each user
When NOMA SIC decoding is used, the user (the user with the largest effective channel gain, namely the 1 st user) arranged at the forefront is decoded last, so that the interference generated by other users (which have been decoded first) on the user can be eliminated; whereas for the K-th user (K ═ 2,3,4, …, K), NOMA multi-user interference comes only from (K-1) users ahead of it. When the sum rate is maximized, the users ranked behind allocate power which only meets the minimum requirement first; the first user gets all the power remaining after the kth user (K2, 3,4, …, K) has been allocated. So the power allocated to user K is:
the power allocated to user k is:
the power allocated to user 1 is:
in the above formulae
RkIs the data rate of the kth user.
(S3-4) determining the sum rate of K users
The sum of the rates of K users is
R is determined according to the following formula1：
And 4, step 4: the sum rates R corresponding to a total of | B | different active sets A' are comparedsumMaximum value of
The corresponding joining beam is b*∈B；
And 5: comparing the maximum sum rate in the step 4 with the sum rate corresponding to the current active set A, if: (a)
if the sum rate is greater than the sum rate corresponding to the current active set a, a beam is added to the active set, that is, a + b*And updating the selectable beam set to S-b*Skipping to the step 3; (b) otherwise, stopping, outputting the active set A as the beam set selected by the MAX-SAB method, and outputting the power distribution p corresponding to the active set Ak,k＝1,2,…,K。
Wherein the content of the first and second substances,
the maximum gain beam selection method comprises the following steps:
step 1: the beam selection network obtains the channel gain of each user on each beam from the channel estimation module
K is 1,2, …, K is the user number, j is 1,2, …, N is the beam number;
step 2: the beam selection network selects an optimal beam j for user k*The wave beam j*Corresponding to the maximum channel power gain of user k, i.e.
Wherein
Is the channel gain of user k on beam j;
and step 3: forming a beam set by the optimal beams of K users, and excluding repeated beams to form a beam set A; the active beam set output by the maximum gain beam selection method is a.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In summary, this summary should not be construed to limit the present invention.
Claims (9)
1. A convex mirror antenna array NOMA transmission system, comprising:
the system comprises a channel estimation module, a NOMA superposition coding module, a digital-to-analog conversion module, an RF link, a beam selection network and a convex mirror antenna array;
the channel estimation module is used for estimating a beam space channel of a user;
the channel estimation module is connected with the beam selection network, and the beam selection network is used for carrying out beam selection and power distribution operation according to the beam space channel of the user to obtain a selected beam and user distribution power;
the beam selection network is connected with the NOMA superposition coding module, and the NOMA superposition coding module is used for carrying out superposition coding operation according to the user distributed power to obtain a digital baseband signal;
the digital-to-analog conversion module is connected with the NOMA superposition coding module and is used for converting the digital baseband signals into analog baseband signals;
the RF link is connected with the digital-to-analog conversion module and is used for converting the analog baseband signal into a radio frequency signal;
the beam selection network is connected to the RF link, and the beam selection network is configured to feed the radio frequency signal onto the selected beam;
the convex mirror antenna array is connected with the beam selection network and is used for transmitting radio frequency signals fed by the beam selection network;
the performing the beam selection and power allocation operation according to the beam space channel of the user to obtain the selected beam and the user allocation power specifically includes:
comparing the gain of all beam space channels of the user, and determining the beam corresponding to the maximum gain as the selected beam of the user;
generating an active beam set according to the selected beams of all the users;
determining a selectable beam set from the active beam set; the intersection of the selectable beam set and the active beam set is an empty set, and the union of the selectable beam set and the active beam set is a set formed by all beams which can be used by the convex mirror antenna array;
determining a corresponding sum rate of the active beam set; the sum rate is the sum of the data rates of all users;
adding each beam of the selectable beam set into the active beam set respectively to obtain a reconstructed active beam set; the number of the reconstructed active beam sets is equal to the number of the elements in the selectable beam sets;
determining and comparing the corresponding sum rates of all the reconstructed activation beam sets to obtain the maximum sum rate;
judging whether the maximum sum rate is greater than the sum rate corresponding to the active beam set; if so, determining the reconstructed beam set corresponding to the maximum sum rate as an updated active beam set, and returning to the step of determining the sum rate corresponding to the active beam set; if not, determining all selected beams in the activated beam set as selected beams;
and determining the user distribution power according to the selected wave beam.
2. The NOMA transmission system as recited in claim 1, wherein the beam selection network comprises:
a plurality of phase shifters; the phase shifter is a 1-bit phase shifter;
each phase shifter is connected with the antennas of the convex mirror antenna array in a one-to-one correspondence mode;
the state of the phase shifter is 0 or 1; when the state of the phase shifter is 0, the antenna connected with the phase shifter is not selected; and when the state of the phase shifter is 1, the antenna connected with the phase shifter is selected.
3. The NOMA transmission system as recited in claim 1, further comprising:
a user receiving module;
the user receiving module is wirelessly connected with the convex mirror antenna array and is used for receiving the radio frequency signals transmitted by the convex mirror antenna array, processing the received signals and then outputting the data information of the user.
4. A NOMA transmission method of a convex mirror antenna array is characterized by comprising the following steps:
acquiring a channel between a user antenna and a convex mirror antenna array;
determining a beam space channel of a user according to a channel between the user antenna and the convex mirror antenna array;
carrying out beam selection and power distribution operation according to the beam space channel of the user to obtain a selected beam and user distribution power;
carrying out signal transmission according to the selected wave beam and the user distributed power;
the performing the beam selection and power allocation operation according to the beam space channel of the user to obtain the selected beam and the user allocation power specifically includes:
comparing the gain of all beam space channels of the user, and determining the beam corresponding to the maximum gain as the selected beam of the user;
generating an active beam set according to the selected beams of all the users;
determining a selectable beam set from the active beam set; the intersection of the selectable beam set and the active beam set is an empty set, and the union of the selectable beam set and the active beam set is a set formed by all beams which can be used by the convex mirror antenna array;
determining a corresponding sum rate of the active beam set; the sum rate is the sum of the data rates of all users;
adding each beam of the selectable beam set into the active beam set respectively to obtain a reconstructed active beam set; the number of the reconstructed active beam sets is equal to the number of the elements in the selectable beam sets;
determining and comparing the corresponding sum rates of all the reconstructed activation beam sets to obtain the maximum sum rate;
judging whether the maximum sum rate is greater than the sum rate corresponding to the active beam set; if so, determining the reconstructed beam set corresponding to the maximum sum rate as an updated active beam set, and returning to the step of determining the sum rate corresponding to the active beam set; if not, determining all selected beams in the activated beam set as selected beams;
and determining the user distribution power according to the selected wave beam.
5. The NOMA transmission method using a convex mirror antenna array as claimed in claim 4, wherein the determining the beam space channel of the user according to the channel between the user antenna and the convex mirror antenna array comprises:
and determining the beam space channel of the user by adopting the following formula according to the channel between the user antenna and the convex mirror antenna array:
wherein the content of the first and second substances,
U＝[a(θ1),a(θ2),…,a(θN)]H
J(N)＝{i-(N-1)/2,i＝0,1,…,N-1}
in the formula (I), the compound is shown in the specification,
beam space channel, h, for a userkFor the channel between the user antenna and the convex mirror antenna array, U is the beam space transformation matrix, a (theta) is the array corresponding vector of the spatial direction angle theta, thetaNIs the nth spatial direction angle, N is the number of antennas in the convex mirror antenna array, j (N) is a set of antenna serial numbers, i is the antenna serial number, and N is the offset antenna serial number.
6. The NOMA transmission method of a convex mirror antenna array as claimed in claim 4, wherein the calculating method of the sum rate specifically includes:
summing the gains of all beam space channels of the user to obtain an effective channel coefficient of the user;
the power gains of the effective channel coefficients of all the users are arranged in a descending order, and the data rate lower limit values of all the users except the user corresponding to the maximum power gain are obtained;
determining the data rate of the user corresponding to the maximum power gain according to the power gain of the effective channel coefficient of the user and the data rate lower limit value;
and summing the data rate of the user corresponding to the maximum power gain and the data rate lower limit values of all the users except the user corresponding to the maximum power gain to obtain a sum rate.
7. The NOMA transmission method of claim 6, wherein the determining the data rate of the user corresponding to the maximum power gain according to the power gain of the effective channel coefficient of the user and the lower limit value of the data rate specifically comprises:
acquiring the sum of the powers;
according to the power gain of the effective channel coefficient of the user and the data rate lower limit value, performing power distribution on the user corresponding to the minimum power gain to obtain first user distribution power;
according to the power sum, the first user distribution power, the power gain of the effective channel coefficient of the user and the data rate lower limit value, performing power distribution on all users except the user corresponding to the maximum power gain and the minimum power gain to obtain a plurality of user distribution powers;
subtracting the sum of the power from the sum of the first user distributed power and the plurality of user distributed powers to obtain the distributed power of the user corresponding to the maximum power gain;
and determining the data rate of the user corresponding to the maximum power gain according to the distributed power of the user corresponding to the maximum power gain and the maximum power gain.
8. A NOMA transmission method as claimed in claim 7,
the performing power distribution on the user corresponding to the minimum power gain according to the power gain of the effective channel coefficient of the user and the data rate lower limit value to obtain first user distributed power specifically includes:
determining the first user allocated power according to the following formula:
in the formula, pKAllocating power, R, to a first userKUsers corresponding to minimum power gainLower limit value of data rate, PtotIs the sum of powers, σ2For noise power, a 'is the active beam set, | a' | is the total number of elements in the active beam set, K is the user serial number corresponding to the minimum power gain,
the power gain for the effective channel coefficient with user number K,
the effective channel coefficient with the user serial number of K;
the allocating power to all users except the user corresponding to the maximum power gain and the minimum power gain according to the power sum, the first user allocated power, the power gain of the effective channel coefficient of the user, and the data rate lower limit value, to obtain a plurality of user allocated powers, specifically including:
determining the distributed power of any user except the user corresponding to the maximum power gain and the minimum power gain according to the following formula:
in the formula, pkDistributing power for users with user serial number k, k being user serial number except the user corresponding to maximum power gain and minimum power gain, RkThe data rate lower limit value of a user with a user serial number k, m is a user serial number variable, pmAllocating power to the user with the user serial number m,
the power gain for the effective channel coefficient with user number k,
the effective channel coefficient with the user serial number k;
the determining the data rate of the user corresponding to the maximum power gain according to the distributed power of the user corresponding to the maximum power gain and the maximum power gain specifically includes:
determining the data rate of the user corresponding to the maximum power gain according to the following formula:
wherein the content of the first and second substances,
in the formula, R1Data rate, p, of the user corresponding to maximum power gain1The allocated power for the user corresponding to the maximum power gain,
for the maximum power gain, the gain is,
the effective channel coefficient of the user corresponding to the maximum power gain.
9. The NOMA transmission method as claimed in claim 4, wherein the transmitting signals according to the selected beam and the allocated power of the user includes:
performing superposition coding operation according to the user distributed power to obtain a digital baseband signal;
converting the digital baseband signal to an analog baseband signal;
converting the analog baseband signal to a radio frequency signal;
feeding the radio frequency signal onto the selected beam;
transmitting the radio frequency signal fed onto the selected beam;
wherein the content of the first and second substances,
the performing superposition coding operation according to the user allocated power to obtain a digital baseband signal specifically includes:
performing superposition coding operation according to the following formula to obtain a digital baseband signal:
where x is the digital baseband signal, skFor user data with user number k, pkAnd allocating power to the user with the user serial number k.
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