CN114844754B - Large-scale terminal multiple access method based on group sequence codebook set - Google Patents

Large-scale terminal multiple access method based on group sequence codebook set Download PDF

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CN114844754B
CN114844754B CN202210507254.7A CN202210507254A CN114844754B CN 114844754 B CN114844754 B CN 114844754B CN 202210507254 A CN202210507254 A CN 202210507254A CN 114844754 B CN114844754 B CN 114844754B
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representing
sequence
user
users
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CN114844754A (en
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张晶
马林
王靖文
梁乐
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Nanjing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • 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
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access, e.g. scheduled or random access
    • H04W74/002—Transmission of channel access control information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access, e.g. scheduled or random access
    • H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
    • H04W74/0833—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention discloses a large-scale terminal multiple access method based on a group sequence codebook set, which comprises the following steps: 1) Grouping a plurality of mctc terminals to construct a plurality of subsystems; 2) Designing a unique spreading sequence codebook set for each subsystem, and distributing a unique spreading sequence in the sequence codebook set for each user in the subsystem; 3) Mapping signals of each subsystem to corresponding time-frequency resource blocks, overlapping and multiplexing partial subcarriers by the time-frequency data blocks of different subsystems, and transmitting the partial subcarriers to a base station through an uplink channel; 4) And the base station performs joint detection on the active users and the data through a CB-GOMP algorithm. The invention is suitable for multi-user detection in a large-scale machine type terminal communication scene, further reduces the correlation between the extension sequences on the basis of improving the system capacity, and improves the accuracy of the joint detection of the active users and the data; meanwhile, the sparse structure of the multi-user signal is combined with a multi-carrier system, so that the frequency spectrum efficiency is further improved.

Description

Large-scale terminal multiple access method based on group sequence codebook set
Technical Field
The invention relates to the technical field of communication, in particular to a large-scale terminal multiple access method based on a block sequence codebook set.
Background
The substantial increase in the number of internet of things devices presents new challenges to the design of wireless systems, wherein large-scale machine type communication (massive Machine Type Communication, mctc) is one of the fundamental components of the fifth generation mobile communication system. Compressive sensing based multi-user detection (Compressive Sensing Multiuser Detection, csmoud) is a candidate to cope with the large-scale connection needs of mctc, which facilitates the use of unlicensed non-orthogonal code division multiple access to accommodate a large number of internet of things devices. The ability of csmu to jointly detect active users and data facilitates reliable detection of direct random access, improving spectral efficiency and simplifying information processing at sensor nodes at the cost of minimal performance loss.
The csmu uses the sporadic transmission characteristics of mctc, and the sparsity introduced from the received signal, thereby detecting whether the sensor is in an active state (activity detection) and the data transmitted by the sensor (data detection). Csmu assigns users a non-orthogonal spreading sequence as their signature, the performance of which often depends on the correlation between spreading sequences. As the number of future users increases, the correlation between the spreading sequences will be higher and higher, which brings challenges to the multi-user detection problem in the mtc network. Attempts have been made to reduce the correlation between sequences by increasing the length of the spreading sequences, but the effect is not obvious and more radio resources are wasted; how to establish a multi-user detection scheme based on various transmission requirements to improve the detection performance of the system is a technical problem to be solved.
Disclosure of Invention
In order to solve the problems, the invention provides a large-scale terminal multiple access method based on a grouping sequence codebook set, which groups all users into a plurality of subsystems, distributes a specific sequence codebook set in each subsystem, and further reduces the correlation between expansion sequences on the basis of improving the system capacity so as to improve the accuracy of joint detection of active users and data; and simultaneously, the CSMUD is combined with a multi-carrier system, and the spectrum efficiency is further improved by increasing the overall load by utilizing the sparse structure of the multi-user signal. Note that in the present invention, the terminal, the sensor node, and the user may be used interchangeably, and the receiving end and the base station may be used interchangeably.
The invention discloses a large-scale terminal multiple access method based on a block sequence codebook set, which comprises the following steps:
step 1, for an mMTC system with a large-scale terminal, grouping all users to form a plurality of user subsystems, and defining a user set of each subsystem;
step 2, designing a unique basic spreading sequence for each subsystem, generating a sequence codebook set of each subsystem according to the sequence, and distributing a unique spreading sequence in the sequence codebook set for each user in the subsystem;
step 3, the user data of each subsystem is added after being modulated and spread by a spreading sequence, and a summation signal of the subsystem is formed; the sum signal of each subsystem is mapped to a plurality of subcarriers through an Orthogonal Frequency Division Multiplexing (OFDM) technology to form a time-frequency data block; the time frequency data blocks of different subsystems overlap and multiplex part of subcarriers and are transmitted to a base station through an uplink channel;
step 4, the base station receives uplink transmission signals of a plurality of subsystems and recovers sum signals of the subsystems; for the sum signal of each subsystem, a group orthogonal matching pursuit (CodebookSequence Block based Group Orthogonal Matching Pursuit, CB-GOMP) algorithm based on a sequence codebook block is adopted to carry out joint detection on active users and user data in the sum signal, so that the random access and data transmission of large-scale users are completed.
Further, in step 1, K users in the mctc system are located within a coverage area of the same base station, and each user initiates an access request and data transmission to a wireless network; dividing all K users into N b Group of N b A subsystem; the subsystem reference number b, which satisfies:
b∈B＝{1,...,N b } (1)
wherein B represents a subsystem index set;
each subsystem contains K b A user, let the user number in subsystem b be k b It satisfies the following conditions:
k b ∈{1,...,K b } (2)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000021
representing the whole;
the data transmission of the users is in sporadic state, and the total number of the users of the whole system is K=N b K b 。
Further, in step 1, it is assumed that the activity probability of each user is p a ，p a =1, i.e. the user has probability p a Transmitting 1-p a Is kept silent; thus, the first and second substrates are bonded together,at any given moment, only a small fraction of the K users are active; when a user is active, it continuously transmits short packet data in a transmission slot.
Further, in step 2, the basic spreading sequence design method of each subsystem is as follows:
by s b Representing the basic spreading sequence of subsystem b, randomly extracting N from the unit circle b Samples, where the ith sample is denoted as
Figure BDA0003637870830000031
Wherein U obeys the interval [0,1 ]]Uniformly distributed on the sample, representing the phase corresponding to the sample;
Figure BDA0003637870830000032
the real and imaginary values of (2) are converted to length +.>
Figure BDA0003637870830000033
Finally splicing them to obtain binary code word with length N c Is the basic spreading sequence s of subsystem b b ；
N b The combining matrix of the basic spreading sequences of the subsystems is expressed as:
Figure BDA0003637870830000034
further, in step 2, the sequence codebook set of the subsystem is composed of a group of spreading sequences, each spreading sequence is generated after cyclic shift of the basic spreading sequence of the subsystem according to a specific shift mode, and the generating method of the sequence codebook set of each subsystem is as follows;
step 2-1, generating a specific shift pattern of the subsystem;
the sub-system B is caused to perform, B e b= {1, N b Specific shift pattern p b The method comprises the following steps:
Figure BDA0003637870830000035
wherein p is b,1 ＝0，K b Representing the number of users in subsystem b; d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure BDA0003637870830000036
represents p b D of (2) b,k The numerical value of the individual elements;
shift pattern p of subsystem b b The mth index value p of (2) b,m M.noteq.1 is calculated from the following formula:
Figure BDA0003637870830000037
wherein N is c Representing the basic spreading sequence s b Is a length of (2);
Figure BDA0003637870830000038
representing the basic spreading sequence s b The new spreading sequence obtained by right shifting the j bits is circularly performed; />
Figure BDA0003637870830000039
Representing the basic spreading sequence s b Cycle right shift p b,i A new spreading sequence of bits; />
Figure BDA0003637870830000041
Representation->
Figure BDA0003637870830000042
And->
Figure BDA0003637870830000043
Is a correlation operation value of (a).
Step 2-2, generating a sequence codebook set of the subsystem;
according to a specific shift pattern p of subsystem b b K in (B) b Element pair basic spreading sequence s b Respectively K b Right shift of sub-cycle to obtain all K in subsystem b b Corresponding spreading sequences for individual users:
Figure BDA0003637870830000044
wherein s is b Representing the basic spreading sequence, p, corresponding to subsystem b b Representing the shift pattern corresponding to subsystem b, which is of length K b Is a vector of (2); d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure BDA0003637870830000045
represents p b D of (2) b,k The numerical value of the individual elements; />
Figure BDA0003637870830000046
Is the sequence s b Circulation right shift->
Figure BDA0003637870830000047
A new sequence generated after the bits;
the set of the spreading sequences is the sequence codebook set of the subsystem b;
spreading sequences of all users in subsystem b form a set
Figure BDA0003637870830000048
Namely, a sequence codebook set of the system b is defined as a sequence codebook matrix +.>
Figure BDA0003637870830000049
Further, in step 3, the modulation, spreading and multiplexing processes of the user data are as follows:
step 3-1, user data of a single subsystem is modulated and spread to form a sum signal;
each user in each subsystem digitally modulates data to be transmitted to form L modulation symbols, and if a certain user does not have data transmission, the user considers that the user transmits L0 s; without loss of generality, the subsystems B, B e b= { 1.. b All users in the matrix of transmit symbols are
Figure BDA00036378708300000410
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA00036378708300000411
representing a size K b A complex set of x L; />
Figure BDA00036378708300000412
For D b Is the kth of (2) b A row vector representing the kth in subsystem b b L consecutive time symbols sent by the individual users; if a certain user k u In a silent state, D b K of (a) u Row fill L0 s; d (D) b Each column vector contains a vector from K b Symbols of individual users;
the user spreads the modulated symbols with its own specific spreading sequence, each modulated symbol forming a length N c Is a spread sequence of (a); the sequences obtained after modulating and spreading the data of all users in each subsystem are added to obtain the sum signal of the subsystem; the sub-system B is caused to perform, B e b= {1, N b Sum signal matrix of } is
Figure BDA0003637870830000051
I.e.
X b ＝D b S b (9)
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000052
a codebook matrix for subsystem b; />
Figure BDA0003637870830000053
Representing a size N c A complex domain space of x L;
the sum signal of each subsystem is mapped to N by OFDM technology s Forming a time-frequency resource block in each subcarrier; the sub-system B is caused to perform, B e b= {1, N b The frequency domain symbol of the sum signal after being transformed by OFDM technology is that
Figure BDA0003637870830000054
Wherein the method comprises the steps of
Figure BDA0003637870830000055
Representing a size N s A complex domain space of x L;
step 3-2, multiplexing and transmitting the sum signals of the subsystems in a carrier partial overlapping mode;
common N in system b Subsystems, thus totally N b Each time-frequency resource block comprises N s Successive subcarriers; having adjacent subsystems multiplex N o Sub-carrier wave, N is more than or equal to 0 o ≤N s ，N b The sum signal of the subsystems is mapped and overlapped into an uplink transmission signal of the system according to the carrier multiplexing pattern
Figure BDA0003637870830000056
Expressed as:
Figure BDA0003637870830000057
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000058
representing a size N max A complex set of x L; by overlapping the multiplexed sub-carriers, the total number of sub-carriers N occupied by the system max The calculation is as follows:
Figure BDA0003637870830000061
defining the ratio of the total number of users carried by the system to the total number of subcarriers as the system carrier load, and calculating the system carrier load as follows by subcarrier multiplexing among subsystems:
Figure BDA0003637870830000062
wherein k=n b K b ；
The signal is fed via an antenna into an uplink channel for transmission to the base station.
Further, in step 4, the base station receives uplink transmission signals of the plurality of subsystems and recovers a sum signal of each subsystem, and the uplink signal receiving and processing steps are as follows:
step 4-1, a base station receives uplink transmission signals of a plurality of subsystems;
considering flat fading channel, frequency domain signal received by base station
Figure BDA0003637870830000063
Expressed as:
Y＝HX+N (12)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000064
representing a size N max A complex domain space of x L; matrix->
Figure BDA0003637870830000065
Representing a matrix of channel coefficients, which is a diagonal matrix, i.e
Figure BDA0003637870830000066
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000067
representing a size N max ×N max Is a complex domain space of (1); h is a s A flat fading coefficient representing subcarrier s; n represents the channel additive white noise matrixIt obeys a mean of 0 variance +.>
Figure BDA0003637870830000068
Complex gaussian distribution of (i.e.)
Figure BDA0003637870830000069
After demodulating and eliminating channel interference by OFDM technique, to simplify system model, let N s ＝N c Will N b Sum signal of subsystem in frequency domain
Figure BDA00036378708300000610
Conversion to time domain sum signal->
Figure BDA0003637870830000071
Step 4-2, the base station recovers the sum transmission signal of each subsystem from the uplink transmission signal;
after receiving uplink signals of active users in a plurality of subsystems, a base station recovers received signals corresponding to a single subsystem through inverse transformation of an OFDM technology; the sum signal of the subsystem b recovered by the base station is received as
Figure BDA0003637870830000072
Y b Expressed as:
Y b ＝H b X b +N b (14)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000073
representing a size N c A complex domain space of x L; matrix->
Figure BDA0003637870830000074
The representation of the sub-system B is given, B e b= {1, N b A sum signal matrix; />
Figure BDA0003637870830000075
Representing a matrix of channel coefficients, which is a diagonal matrix, a tableThe method is shown as follows:
H b ＝diag{h b } (15)
wherein the vector is
Figure BDA0003637870830000076
Representing the set of flat fading coefficients for each end user in subsystem b, +.>
Figure BDA0003637870830000077
Representing the flat fading coefficient of end user k in subsystem b; n (N) b Mean 0 variance +.>
Figure BDA0003637870830000078
Is an additive white gaussian noise matrix, i.e +.>
Figure BDA0003637870830000079
And 4-3, the base station jointly detects active users and user data from each subsystem and signals by adopting a CB-GOMP algorithm.
Further, the CB-GOMP algorithm is utilized to iteratively detect active users in each subsystem and restore the transmission signals thereof so as to realize the sequence codebook of the subsystem b
Figure BDA00036378708300000710
Receiving signal Y as input, estimation matrix of user in subsystem +.>
Figure BDA00036378708300000711
As an output; the CB-GOMP algorithm comprises the following specific steps:
step 4-3-1, initializing algorithm parameters;
let the estimation of the support set of subsystem b, i.e. the active user sequence number set in subsystem b be Γ b Its initial value
Figure BDA00036378708300000712
Is empty, i.e.)>
Figure BDA00036378708300000713
Let the iteration number of the codebook index of the detection subsystem be g, and the initial value of the iteration number q of the active user data in the detection subsystem b be 0; the base station receives the signals Y of all subsystems as follows:
Figure BDA00036378708300000714
Figure BDA0003637870830000081
wherein y is l A first symbol representing a current frame; n (N) c L is the number of symbols transmitted in one frame, which is the length of the spreading sequence; will y l Divided into N b A sub-signal as shown in formula (17);
Figure BDA0003637870830000082
representing y l Grouping the obtained g sub-signals; residual r represents the difference between the received signal and the algorithm recovery signal, residual r l Representing the received signal y l And algorithm recovery signal->
Figure BDA0003637870830000083
The difference of (1) is not less than 1 and not more than L; />
Figure BDA0003637870830000084
Representing the residual error when the iteration number is q-1; />
Figure BDA0003637870830000085
Representing residual error r l Of (1), wherein>
Figure BDA0003637870830000086
Initialized to->
Figure BDA0003637870830000087
g is initialized to 1; executing the step 4-3-2;
step 4-3-2, detecting subsystem codebook indexes of active users;
l symbols of a received frame, i.e
Figure BDA0003637870830000088
Respectively obtaining sequence codebook sets S by using (18) b Each column is->
Figure BDA0003637870830000089
And L groups of initial residuals->
Figure BDA00036378708300000810
Is the sum of the inner product values of (2), compare N b The summation results are combined to obtain a group of codebook indexes I of the corresponding subsystems with the largest summation results g Then, executing the step 4-3-3;
Figure BDA00036378708300000811
step 4-3-3, detecting an active user index; by I g Corresponding set of sequence codebooks
Figure BDA00036378708300000812
And residual error->
Figure BDA00036378708300000813
Performing group orthogonal matching pursuit GOMP algorithm solution;
detection of active users based on obtaining a user index corresponding to the maximum correlation value of the codebook spreading sequence from the received signal, iteratively solving for the sequence codebook set by equation (19)
Figure BDA00036378708300000814
Residual values of each column and L groups->
Figure BDA00036378708300000815
Is the sum of the inner products of (C) and (D) is compared with K b The summation results are combined to obtain the index of a group of corresponding active users with the largest summation result value, and the subsystem I is updated by using the formula (20) g Middle activitiesA support set for the user; executing the step 4-3-4;
Figure BDA00036378708300000816
Figure BDA00036378708300000817
step 4-3-4, detecting subsystem activity user data;
using the least squares estimation to estimate subsystem I at the current iteration using equation (21) g Set of user data in (a)
Figure BDA0003637870830000091
Wherein->
Figure BDA0003637870830000092
Representing pseudo-inverse calculations; traversing loop L groups of residuals->
Figure BDA0003637870830000093
Then, executing the step 4-3-5;
Figure BDA0003637870830000094
step 4-3-5, updating residual errors; from the current detected user's spreading sequence, according to equation (22)
Figure BDA0003637870830000095
The contribution of the estimated data is subtracted to update the residual +.>
Figure BDA0003637870830000096
According to formula (23), stopping updating when the residual energy is smaller than the threshold value to obtain the current detection subsystem I g Estimate matrix of user data in->
Figure BDA0003637870830000097
And preserveEstimation matrix to System user data +.>
Figure BDA0003637870830000098
In (a) and (b); traversing updating L groups of residuals->
Figure BDA0003637870830000099
After the detection of the active user data of the current subsystem is finished, executing the steps 4-3-6;
Figure BDA00036378708300000910
||r||＜γ (23)
step 4-3-6, carrying out iterative detection on the active users and data of the next subsystem; updating g to g+1, then grouping signals
Figure BDA00036378708300000911
Updated to->
Figure BDA00036378708300000912
Using the detected support set and the sequence codebook set of the subsystem, according to formula (24), thereby eliminating interference of the detected active user data of the subsystem to the active user data of the subsystem to be tested; the signal after interference elimination is +.>
Figure BDA00036378708300000913
Wherein->
Figure BDA00036378708300000914
Can be expressed as:
Figure BDA00036378708300000915
iterative updating of initial residuals
Figure BDA00036378708300000916
Returning to step 4-3-2, active users and data of the subsystem to be testedDetecting and updating subsystem I g+1 Estimation matrix of user data->
Figure BDA00036378708300000917
The detected subsystem is not repeatedly detected; until the iteration number reaches g > N b When the joint detection of the active user and the data is finished, an estimation matrix of the system user data is obtained>
Figure BDA00036378708300000918
The beneficial effects of the invention are as follows: (1) The method of the invention improves the relativity problem of the spreading sequences among users, and based on the method of the group sequence codebook set, the basic spreading sequences form a specific cyclic shift version, thereby reducing signaling overhead, further reducing relativity among the spreading sequences on the basis of improving system capacity, and further improving the accuracy of the joint detection of the active users and the data;
(2) The method combines the CSMUD with the multi-carrier system, utilizes the sparse structure of the multi-user signal, further improves the frequency spectrum efficiency by increasing the overall load, and improves the performance of the CSMUD by a CB-GOMP algorithm.
Drawings
Fig. 1 is a flowchart of a method for massive terminal multiple access based on a block sequence codebook set according to an embodiment of the present invention;
FIG. 2 is a system scene diagram according to an embodiment of the invention;
FIG. 3 is a diagram showing the allocation of spreading sequences in an embodiment of the present invention;
FIG. 4 is a process diagram of a sensor node in an embodiment of the invention;
FIG. 5 is a resource block diagram of a subsystem CSMUD in an embodiment of the invention;
FIG. 6 is a flowchart of a CB-GOMP algorithm in an embodiment of the invention. .
Detailed Description
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings.
The flow chart of the large-scale terminal multiple access method based on the block sequence codebook set is shown in fig. 1, and the method comprises the following steps:
in step 1, consider a typical uplink mctc system scenario, as shown in fig. 2; k users in the mMTC system are located in the coverage area of the same base station, and each user can initiate an access request and data transmission to a wireless network; dividing all K users into N b Group of N b A subsystem; the subsystem reference number b, which satisfies:
b∈B＝{1,...,N b } (1)
wherein B represents a subsystem index set;
each subsystem contains K b A user, let the user number in subsystem b be k b It satisfies the following conditions:
k b ∈{1,...,K b } (2)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000101
representing the whole;
the data transmission of the users is in sporadic state, and the total number of the users of the whole system is K=N b K b 。
Assuming that the activity probability of each user is p a ，p a =1, i.e. the user has probability p a Transmitting 1-p a Is kept silent; thus, at any given moment, only a small fraction of the K users are active; when a user is active, it continuously transmits short packet data in a transmission slot.
In step 2, the basic spreading sequence design method of each subsystem is as follows:
by s b Representing the basic spreading sequence of subsystem b, randomly extracting N from the unit circle b A number of samples of the sample were taken,wherein the ith sample is represented as
Figure BDA0003637870830000111
Wherein U obeys the interval [0,1 ]]Uniformly distributed on the sample, representing the phase corresponding to the sample;
Figure BDA0003637870830000112
the real and imaginary values of (2) are converted to length +.>
Figure BDA0003637870830000113
Finally splicing them to obtain binary code word with length N c Is the basic spreading sequence s of subsystem b b ；
N b The combining matrix of the basic spreading sequences of the subsystems is expressed as:
Figure BDA0003637870830000114
in step 2, the sequence codebook set of the subsystem is composed of a group of spreading sequences, each spreading sequence is generated after cyclic shift of the basic spreading sequence of the subsystem according to a specific shift mode, and the generating method of the sequence codebook set of each subsystem is as follows;
step 2-1, generating a specific shift pattern of the subsystem;
the sub-system B is caused to perform, B e b= {1, N b Specific shift pattern p b The method comprises the following steps:
Figure BDA0003637870830000115
wherein p is b,1 ＝0，K b Representing the number of users in subsystem b; d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure BDA0003637870830000116
represents p b D of (2) b,k The numerical value of the individual elements;
shift pattern p of subsystem b b The mth index value p of (2) b,m M.noteq.1 is calculated from the following formula:
Figure BDA0003637870830000121
wherein N is c Representing the basic spreading sequence s b Is a length of (2);
Figure BDA0003637870830000122
representing the basic spreading sequence s b The new spreading sequence obtained by right shifting the j bits is circularly performed; />
Figure BDA0003637870830000123
Representing the basic spreading sequence s b Cycle right shift p b,i A new spreading sequence of bits; />
Figure BDA0003637870830000124
Representation->
Figure BDA0003637870830000125
And->
Figure BDA0003637870830000126
Related operational values of (2);
step 2-2, generating a sequence codebook set of the subsystem;
according to a specific shift pattern p of subsystem b b K in (B) b Element pair basic spreading sequence s b Respectively K b Right shift of sub-cycle to obtain all K in subsystem b b Corresponding spreading sequences for individual users:
Figure BDA0003637870830000127
wherein s is b Representing the basic spreading sequence, p, corresponding to subsystem b b Representing the shift pattern corresponding to subsystem b, which is of length K b Is a vector of (2); d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure BDA0003637870830000128
represents p b D of (2) b,k The numerical value of the individual elements; />
Figure BDA0003637870830000129
Is the sequence s b Circulation right shift->
Figure BDA00036378708300001210
A new sequence generated after the bits;
the set of the spreading sequences is the sequence codebook set of the subsystem b;
as shown in fig. 3, the spreading sequences of all users in subsystem b form a set
Figure BDA00036378708300001211
Namely, a sequence codebook set of the system b is defined as a sequence codebook matrix +.>
Figure BDA00036378708300001212
In step 3, the modulation, spreading and multiplexing processes of the user data are shown in fig. 4, and the specific steps are as follows:
step 3-1, user data of a single subsystem is modulated and spread to form a sum signal;
each user in each subsystem digitally modulates data to be transmitted to form L modulation symbols, and if a certain user does not have data transmission, the user considers that the user transmits L0 s; without loss of generality, the subsystems B, B e b= { 1.. b All users in the matrix of transmit symbols are
Figure BDA0003637870830000131
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000132
representing a size K b A complex set of x L; />
Figure BDA0003637870830000133
For D b Is the kth of (2) b A row vector representing the kth in subsystem b b L consecutive time symbols sent by the individual users; if a certain user k u In a silent state, D b K of (a) u Row fill L0 s; d (D) b Each column vector contains a vector from K b Symbols of individual users;
the user spreads the modulated symbols with its own specific spreading sequence, each modulated symbol forming a length N c Is a spread sequence of (a); the sequences obtained after modulating and spreading the data of all users in each subsystem are added to obtain the signals of the subsystem; the sub-system B is caused to perform, B e b= {1, N b The signal matrix of } is
Figure BDA0003637870830000134
I.e.
X b ＝D b S b (9)
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000135
a codebook matrix for subsystem b; />
Figure BDA0003637870830000136
Representing a size N c A complex domain space of x L;
the sum signal of each subsystem is mapped to N by OFDM technology s Forming a time-frequency resource block in each subcarrier, wherein the time-frequency resource block of the CSMUD of the single subsystem is shown in fig. 5; the sub-system B is caused to perform, B e b= {1, N b The frequency domain symbol of the sum signal after being transformed by OFDM technology is that
Figure BDA0003637870830000137
Wherein->
Figure BDA0003637870830000138
Representing a size N s A complex domain space of x L;
step 3-2, multiplexing and transmitting the sum signals of the subsystems in a carrier partial overlapping mode;
common N in system b Subsystems, thus totally N b Each time-frequency resource block comprises N s Successive subcarriers; having adjacent subsystems multiplex N o Sub-carrier wave, N is more than or equal to 0 o ≤N s ，N b The sum signal of the subsystems is mapped and overlapped into an uplink transmission signal of the system according to the carrier multiplexing pattern
Figure BDA0003637870830000139
Expressed as:
Figure BDA0003637870830000141
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000142
representing a size N max A complex set of x L; by overlapping the multiplexed sub-carriers, the total number of sub-carriers N occupied by the system max The calculation is as follows:
Figure BDA0003637870830000143
defining the ratio of the total number of users carried by the system to the total number of subcarriers as the system carrier load, and calculating the system carrier load as follows by subcarrier multiplexing among subsystems:
Figure BDA0003637870830000144
wherein k=n b K b ；
The signal is fed via an antenna into an uplink channel for transmission to the base station.
In step 4, the base station receives uplink transmission signals of a plurality of subsystems and recovers sum signals of the subsystems, and the uplink signal receiving and processing steps are as follows:
step 4-1, a base station receives uplink transmission signals of a plurality of subsystems;
considering flat fading channel, frequency domain signal received by base station
Figure BDA0003637870830000145
Expressed as: />
Y＝HX+N (12)
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000146
representing a size N max A complex domain space of x L; matrix->
Figure BDA0003637870830000147
Representing a matrix of channel coefficients, which is a diagonal matrix, i.e
Figure BDA0003637870830000151
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000152
representing a size N max ×N max Is a complex domain space of (1); h is a s A flat fading coefficient representing subcarrier s;Nrepresenting a channel additive white noise matrix subject to a mean of 0 variance +.>
Figure BDA0003637870830000153
Complex gaussian distribution of (i.e.)
Figure BDA0003637870830000154
By OFDM technologyAfter the demodulation and cancellation of channel interference, to simplify the system model, let N s ＝N c Will N b Sum signal of subsystem in frequency domain
Figure BDA0003637870830000155
Conversion to time domain sum signal->
Figure BDA0003637870830000156
Step 4-2, the base station recovers the sum transmission signal of each subsystem from the uplink transmission signal;
after receiving uplink signals of active users in a plurality of subsystems, a base station recovers received signals corresponding to a single subsystem through inverse transformation of an OFDM technology; the base station receives the recovered signal of the subsystem b as
Figure BDA0003637870830000157
Y b Expressed as:
Y b ＝H b X b +N b (14)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0003637870830000158
representing a size N c A complex domain space of x L; matrix->
Figure BDA0003637870830000159
The representation of the sub-system B is given, B e b= {1, N b A sum signal matrix; />
Figure BDA00036378708300001510
Representing the channel coefficient matrix, which is a diagonal matrix, expressed as:
H b ＝diag{h b } (15)
wherein the vector is
Figure BDA00036378708300001511
Representing the set of flat fading coefficients for each end user in subsystem b, +.>
Figure BDA00036378708300001512
Representing the flat fading coefficient of end user k in subsystem b; n (N) b Mean 0 variance +.>
Figure BDA00036378708300001513
Is an additive white gaussian noise matrix, i.e +.>
Figure BDA00036378708300001514
And 4-3, the base station jointly detects active users and user data from each subsystem and signals by adopting a CB-GOMP algorithm.
As shown in fig. 6, active users in each subsystem are iteratively detected and their transmission signals are restored by using CB-GOMP algorithm to sequence codebook of subsystem b
Figure BDA0003637870830000161
Receiving signal Y as input, estimation matrix of user in subsystem +.>
Figure BDA0003637870830000162
As an output; the CB-GOMP algorithm comprises the following specific steps:
step 4-3-1, initializing algorithm parameters;
let the estimation of the support set of subsystem b, i.e. the active user sequence number set in subsystem b be Γ b Its initial value
Figure BDA0003637870830000163
Is empty, i.e.)>
Figure BDA0003637870830000164
Let the iteration number of the codebook index of the detection subsystem be g, and the initial value of the iteration number q of the active user data in the detection subsystem b be 0; the base station receives the signals Y of all subsystems as follows:
Figure BDA0003637870830000165
Figure BDA0003637870830000166
wherein y is l A first symbol representing a current frame; n (N) c L is the number of symbols transmitted in one frame, which is the length of the spreading sequence; will y l Divided into N b A sub-signal as shown in formula (17);
Figure BDA0003637870830000167
representing y l Grouping the obtained g sub-signals; residual r represents the difference between the received signal and the algorithm recovery signal, residual r l Representing the received signal y l And algorithm recovery signal->
Figure BDA0003637870830000168
The difference of (1) is not less than 1 and not more than L; />
Figure BDA0003637870830000169
Representing the residual error when the iteration number is q-1; />
Figure BDA00036378708300001610
Representing residual error r l Of (1), wherein>
Figure BDA00036378708300001611
Initialized to->
Figure BDA00036378708300001612
g is initialized to 1; executing the step 4-3-2;
step 4-3-2, detecting subsystem codebook indexes of active users;
l symbols of a received frame (i.e
Figure BDA00036378708300001613
Respectively obtaining sequence codebook sets S by using (18) b Each column (i.e.)>
Figure BDA00036378708300001614
) And L groups of initial residuals->
Figure BDA00036378708300001615
Is the sum of the inner product values of (2), compare N b The summation results are combined to obtain a group of codebook indexes I of the corresponding subsystems with the largest summation results g Then, executing the step 4-3-3;
Figure BDA00036378708300001616
step 4-3-3, detecting an active user index; by I g Corresponding set of sequence codebooks
Figure BDA0003637870830000171
And residual error->
Figure BDA0003637870830000172
Performing group orthogonal matching pursuit GOMP algorithm solution;
detection of active users based on obtaining a user index corresponding to the maximum correlation value of the codebook spreading sequence from the received signal, iteratively solving for the sequence codebook set by equation (19)
Figure BDA0003637870830000173
Residual values of each column and L groups->
Figure BDA0003637870830000174
Is the sum of the inner products of (C) and (D) is compared with K b The summation results are combined to obtain the index of a group of corresponding active users with the largest summation result value, and the subsystem I is updated by using the formula (20) g A support set for active users; executing the step 4-3-4;
Figure BDA0003637870830000175
Figure BDA0003637870830000176
step 4-3-4, detecting subsystem activity user data;
using the least squares estimation to estimate subsystem I at the current iteration using equation (21) g Set of user data in (a)
Figure BDA0003637870830000177
Wherein->
Figure BDA0003637870830000178
Representing pseudo-inverse calculations; traversing loop L groups of residuals->
Figure BDA0003637870830000179
Then, executing the step 4-3-5;
Figure BDA00036378708300001710
/>
step 4-3-5, updating residual errors; from the current detected user's spreading sequence, according to equation (22)
Figure BDA00036378708300001711
The contribution of the estimated data is subtracted to update the residual +.>
Figure BDA00036378708300001712
According to formula (23), stopping updating when the residual energy is smaller than the threshold value to obtain the current detection subsystem I g Estimate matrix of user data in->
Figure BDA00036378708300001713
And saved to the estimation matrix of the system user data +.>
Figure BDA00036378708300001714
In (a) and (b); traversing updating L groups of residuals->
Figure BDA00036378708300001715
After that, the current sonAfter the detection of the active user data of the system is finished, executing the steps 4-3-6;
Figure BDA00036378708300001716
||r||＜γ (23)
step 4-3-6, carrying out iterative detection on the active users and data of the next subsystem; updating g to g+1, then grouping signals
Figure BDA00036378708300001717
Updated to->
Figure BDA00036378708300001718
Using the detected support set and the sequence codebook set of the subsystem, according to formula (24), thereby eliminating interference of the detected active user data of the subsystem to the active user data of the subsystem to be tested; the signal after interference elimination is +.>
Figure BDA0003637870830000181
Wherein->
Figure BDA0003637870830000182
Can be expressed as:
Figure BDA0003637870830000183
iterative updating of initial residuals
Figure BDA0003637870830000184
Returning to step 4-3-2, detecting the active users and data of the subsystem to be detected, and updating the subsystem I g+1 Estimation matrix of user data->
Figure BDA0003637870830000185
The detected subsystem is not repeatedly detected; until the iteration number reaches g > N b When the joint detection of the active user and the data is finished, the method obtainsEstimation matrix of system user data>
Figure BDA0003637870830000186
The above description is merely of preferred embodiments of the present invention, and the scope of the present invention is not limited to the above embodiments, but all equivalent modifications or variations according to the present disclosure will be within the scope of the claims.

Claims (6)

1. The large-scale terminal multiple access method based on the group sequence codebook set is characterized by comprising the following steps:
step 1, for an mMTC system with a large-scale terminal, grouping all users to form a plurality of user subsystems, and defining a user set of each subsystem;
step 2, designing a unique basic spreading sequence for each subsystem, generating a sequence codebook set of each subsystem according to the sequence, and distributing a unique spreading sequence in the sequence codebook set for each user in the subsystem;
in step 2, the basic spreading sequence design method of each subsystem is as follows:
by s b Representing the basic spreading sequence of subsystem b, randomly extracting N from the unit circle b Samples, where the ith sample is denoted as
Figure FDA0004233201800000011
Wherein U obeys the interval [0,1 ]]Uniformly distributed on the sample, representing the phase corresponding to the sample;
Figure FDA0004233201800000012
the real and imaginary values of (2) are converted to length +.>
Figure FDA0004233201800000013
Finally splicing them to obtain binary code word with length N c Is the basic spreading sequence s of subsystem b b ；
N b The combining matrix of the basic spreading sequences of the subsystems is expressed as:
Figure FDA0004233201800000014
the sequence codebook set of the subsystem consists of a group of spreading sequences, each spreading sequence is generated after cyclic shift of a basic spreading sequence of the subsystem according to a specific shift mode, and the generation method of the sequence codebook set of each subsystem is as follows;
step 2-1, generating a specific shift pattern of the subsystem;
the sub-system B is caused to perform, B e b= {1, N b Specific shift pattern p b The method comprises the following steps:
Figure FDA0004233201800000015
wherein p is b,1 ＝0，K b Representing the number of users in subsystem b; d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure FDA0004233201800000016
represents p b D of (2) b,k The numerical value of the individual elements;
shift pattern p of subsystem b b The mth index value p of (2) b,m M.noteq.1 is calculated from the following formula:
Figure FDA0004233201800000021
wherein N is c Representing the basic spreading sequence s b Is a length of (2);
Figure FDA0004233201800000022
representing the basic spreading sequence s b The new spreading sequence obtained by right shifting the j bits is circularly performed; />
Figure FDA0004233201800000023
Representing the basic spreading sequence s b Cycle right shift p b,i A new spreading sequence of bits; />
Figure FDA0004233201800000024
Representation of
Figure FDA0004233201800000025
And->
Figure FDA0004233201800000026
Related operational values of (2);
step 2-2, generating a sequence codebook set of the subsystem;
according to a specific shift pattern p of subsystem b b K in (B) b Element pair basic spreading sequence s b Respectively K b Right shift of sub-cycle to obtain all K in subsystem b b Corresponding spreading sequences for individual users:
Figure FDA0004233201800000027
wherein s is b Representing the basic spreading sequence, p, corresponding to subsystem b b Representing the shift pattern corresponding to subsystem b, which is of length K b Is a vector of (2); d, d b,k Representing user k at p in subsystem b b Index in (i.e. vector p) b D of (2) b,k An element;
Figure FDA0004233201800000028
represents p b D of (2) b,k The numerical value of the individual elements; />
Figure FDA0004233201800000029
Is the sequence s b Circulation right shift->
Figure FDA00042332018000000210
A new sequence generated after the bits;
the set of the spreading sequences is the sequence codebook set of the subsystem b;
spreading sequences of all users in subsystem b form a set
Figure FDA00042332018000000211
Namely, a sequence codebook set of the system b is defined as a sequence codebook matrix +.>
Figure FDA00042332018000000212
Step 3, the user data of each subsystem is added after being modulated and spread by a spreading sequence, and a summation signal of the subsystem is formed; the sum signal of each subsystem is mapped to a plurality of subcarriers through OFDM technology to form a time-frequency data block; the time frequency data blocks of different subsystems overlap and multiplex part of subcarriers and are transmitted to a base station through an uplink channel;
step 4, the base station receives uplink transmission signals of a plurality of subsystems and recovers sum signals of the subsystems; and for the sum signal of each subsystem, adopting a group orthogonal matching pursuit algorithm based on a sequence codebook block to perform joint detection on the active users and the user data in the sum signal, and completing the random access and data transmission of large-scale users.
2. The method for multiple access of a large-scale terminal based on a group sequence codebook set according to claim 1, wherein in step 1, K users in the mctc system are located in a coverage area of the same base station, and each user initiates an access request and data transmission to a wireless network; dividing all K users into N b Group of N b A subsystem; the subsystem reference number b, which satisfies:
b∈B＝{1,...,N b } (1)
wherein B represents a subsystem index set;
each subsystem contains K b A user, let the user number in subsystem b be k b It satisfies the following conditions:
k b ∈{1,...,K b } (2)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000031
Figure FDA0004233201800000032
representing the whole;
the data transmission of the users is in sporadic state, and the total number of the users of the whole system is K=N b K b 。
3. The method for massive terminal multiple access based on a set of block sequence codebooks according to claim 2, wherein in step 1, it is assumed that the activity probability of each user is p a ，p a =1, i.e. the user has probability p a Transmitting 1-p a Is kept silent; thus, at any given moment, only a small fraction of the K users are active; when a user is active, it continuously transmits short packet data in a transmission slot.
4. The method for multiple access of a large-scale terminal based on a block sequence codebook set according to claim 1, wherein in step 3, the modulation, spreading, multiplexing process of the user data is as follows:
step 3-1, user data of a single subsystem is modulated and spread to form a sum signal;
each user in each subsystem digitally modulates data to be transmitted to form L modulation symbols, and if a certain user does not have data transmission, the user considers that the user transmits L0 s; without loss of generality, the subsystems B, B e b= { 1.. b The transmit symbol matrix for all users in } is:
Figure FDA0004233201800000033
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000034
representing a size K b A complex set of x L; />
Figure FDA0004233201800000035
For D b Is the kth of (2) b A row vector representing the kth in subsystem b b L consecutive time symbols sent by the individual users; if a certain user k u In a silent state, D b K of (a) u Row fill L0 s; d (D) b Each column vector contains a vector from K b Symbols of individual users;
the user spreads the modulated symbols with its own specific spreading sequence, each modulated symbol forming a length N c Is a spread sequence of (a); the sequences obtained after modulating and spreading the data of all users in each subsystem are added to obtain the sum signal of the subsystem; the sub-system B is caused to perform, B e b= {1, N b Sum signal matrix of } is
Figure FDA0004233201800000041
I.e.
X b ＝D b S b (9)
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000042
a codebook matrix for subsystem b; />
Figure FDA0004233201800000043
Representing a size N c A complex domain space of x L;
sum message of each subsystemMapping numbers to N by OFDM techniques s Forming a time-frequency resource block in each subcarrier; the sub-system B is caused to perform, B e b= {1, N b The frequency domain symbol of the sum signal after being transformed by OFDM technology is that
Figure FDA0004233201800000044
Wherein the method comprises the steps of
Figure FDA0004233201800000045
Representing a size N s A complex domain space of x L;
step 3-2, multiplexing and transmitting the sum signals of the subsystems in a carrier partial overlapping mode;
common N in system b Subsystems, thus totally N b Each time-frequency resource block comprises N s Successive subcarriers; having adjacent subsystems multiplex N o Sub-carrier wave, N is more than or equal to 0 o ≤N s ，N b The sum signal of the subsystems is mapped and overlapped into an uplink transmission signal of the system according to the carrier multiplexing pattern
Figure FDA0004233201800000046
Expressed as:
Figure FDA0004233201800000051
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000052
representing a size N max A complex set of x L; by overlapping the multiplexed sub-carriers, the total number of sub-carriers N occupied by the system max The calculation is as follows:
Figure FDA0004233201800000053
defining the ratio of the total number of users carried by the system to the total number of subcarriers as the system carrier load, and calculating the system carrier load as follows by subcarrier multiplexing among subsystems:
Figure FDA0004233201800000054
wherein k=n b K b ；
The signal is fed via an antenna into an uplink channel for transmission to the base station.
5. The method for multiple access of a large-scale terminal based on a group sequence codebook set according to claim 1, wherein in step 4, the base station receives uplink transmission signals of a plurality of subsystems and recovers a sum signal of each subsystem, and the uplink signal receiving and processing steps are as follows:
step 4-1, a base station receives uplink transmission signals of a plurality of subsystems;
considering flat fading channel, frequency domain signal received by base station
Figure FDA0004233201800000055
Expressed as:
Y＝HX+N (12)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000056
representing a size N max A complex domain space of x L; matrix->
Figure FDA0004233201800000057
Representing a matrix of channel coefficients, which is a diagonal matrix, i.e
Figure FDA0004233201800000061
Wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000062
representing a size N max ×N max Is a complex domain space of (1); h is a s A flat fading coefficient representing subcarrier s;Nrepresenting a channel additive white noise matrix subject to a mean of 0 variance +.>
Figure FDA0004233201800000063
Is of complex Gaussian distribution, i.e.)>
Figure FDA0004233201800000064
After demodulating and eliminating channel interference by OFDM technique, to simplify system model, let N s ＝N c Will N b Sum signal of subsystem in frequency domain
Figure FDA0004233201800000065
Conversion to time domain sum signal->
Figure FDA0004233201800000066
Step 4-2, the base station recovers the sum transmission signal of each subsystem from the uplink transmission signal;
after receiving uplink signals of active users in a plurality of subsystems, a base station recovers received signals corresponding to a single subsystem through inverse transformation of an OFDM technology; the sum signal of the subsystem b recovered by the base station is received as
Figure FDA0004233201800000067
Y b Expressed as:
Y b ＝H b X b +N b (14)
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure FDA0004233201800000068
representing a size N c A complex domain space of x L; matrix->
Figure FDA0004233201800000069
The representation of the sub-system B is given, B e b= {1, N b A sum signal matrix; />
Figure FDA00042332018000000610
Representing the channel coefficient matrix, which is a diagonal matrix, expressed as:
H b ＝diag{h b } (15)
wherein the vector is
Figure FDA00042332018000000611
Representing the set of flat fading coefficients for each end user in subsystem b, +.>
Figure FDA00042332018000000612
Representing the flat fading coefficient of end user k in subsystem b; n (N) b Mean 0 variance +.>
Figure FDA00042332018000000613
Is an additive white gaussian noise matrix, i.e +.>
Figure FDA00042332018000000614
And 4-3, the base station jointly detects active users and user data from each subsystem and signals by adopting a CB-GOMP algorithm.
6. The method for multiple access of a large-scale terminal based on a block sequence codebook set according to claim 5, wherein active users in each subsystem are iteratively detected and their transmission signals are restored by using CB-GOMP algorithm to sequence codebook of subsystem b
Figure FDA0004233201800000071
Receiving signal Y as input, estimation matrix of user in subsystem +.>
Figure FDA0004233201800000072
As an output; the CB-GOMP algorithm comprises the following specific steps:
step 4-3-1, initializing algorithm parameters;
let the estimation of the support set of subsystem b, i.e. the active user sequence number set in subsystem b be Γ b Its initial value
Figure FDA0004233201800000073
Is empty, i.e.)>
Figure FDA0004233201800000074
Let the iteration number of the codebook index of the detection subsystem be g, and the initial value of the iteration number q of the active user data in the detection subsystem b be 0; the base station receives the signals Y of all subsystems as
Figure FDA0004233201800000075
Figure FDA0004233201800000076
Wherein y is l A first symbol representing a current frame; n (N) c L is the number of symbols transmitted in one frame, which is the length of the spreading sequence; will y l Divided into N b A sub-signal as shown in formula (17);
Figure FDA0004233201800000077
representing y l Grouping the obtained g sub-signals; residual r represents the difference between the received signal and the algorithm recovery signal, residual r l Representing the received signal y l And algorithm recovery signal->
Figure FDA0004233201800000078
The difference of (1) is not less than 1 and not more than L; r is (r) l q-1 Representing the residual error when the iteration number is q-1; r is (r) l 0 Representing residual errorsr l Wherein r is the initial value of l 0 Initialized to->
Figure FDA0004233201800000079
g is initialized to 1; executing the step 4-3-2;
step 4-3-2, detecting subsystem codebook indexes of active users;
l symbols of a received frame, i.e
Figure FDA00042332018000000710
Respectively obtaining sequence codebook sets S by using (18) b Each column is->
Figure FDA00042332018000000711
With L groups of initial residuals r l 0 Is the sum of the inner product values of (2), compare N b The summation results are combined to obtain a group of codebook indexes I of the corresponding subsystems with the largest summation results g Then, executing the step 4-3-3;
Figure FDA0004233201800000081
step 4-3-3, detecting an active user index; by I g Corresponding set of sequence codebooks
Figure FDA0004233201800000082
And residual error r l q-1 Performing group orthogonal matching pursuit GOMP algorithm solution;
detection of active users based on obtaining a user index corresponding to the maximum correlation value of the codebook spreading sequence from the received signal, iteratively solving for the sequence codebook set by equation (19)
Figure FDA0004233201800000083
Residual values r of each column and L groups l q-1 Is the sum of the inner products of (C) and (D) is compared with K b The summation results are combined to obtain a group of corresponding active users with the largest summation result valuesIndex, update subsystem I using equation (20) g A support set for active users; executing the step 4-3-4;
Figure FDA0004233201800000084
Figure FDA0004233201800000085
step 4-3-4, detecting subsystem activity user data;
using the least squares estimation to estimate subsystem I at the current iteration using equation (21) g Set of user data in (a)
Figure FDA0004233201800000086
Wherein->
Figure FDA0004233201800000087
Representing pseudo-inverse calculations; traversing loop L groups of residuals r l 0 Then, executing the step 4-3-5;
Figure FDA0004233201800000088
step 4-3-5, updating residual errors; from r, using the spreading sequence of the currently detected user, according to equation (22) l 0 Subtracting contribution of estimated data to update residual r l q The method comprises the steps of carrying out a first treatment on the surface of the According to formula (23), stopping updating when the residual energy is smaller than the threshold value to obtain the current detection subsystem I g Estimation matrix of user data in a network
Figure FDA0004233201800000089
And saved to the estimation matrix of the system user data +.>
Figure FDA00042332018000000810
In (a) and (b); traversing and updating L groups of residual errors r l q After the detection of the active user data of the current subsystem is finished, executing the steps 4-3-6;
Figure FDA00042332018000000811
||r||＜γ (23)
step 4-3-6, carrying out iterative detection on the active users and data of the next subsystem; updating g to g+1, then grouping signals
Figure FDA0004233201800000091
Updated to->
Figure FDA0004233201800000092
Using the detected support set and the sequence codebook set of the subsystem, according to formula (24), thereby eliminating interference of the detected active user data of the subsystem to the active user data of the subsystem to be tested; the signal after interference elimination is +.>
Figure FDA0004233201800000093
Wherein->
Figure FDA0004233201800000094
Can be expressed as:
Figure FDA0004233201800000095
iterative updating of initial residuals
Figure FDA0004233201800000096
Returning to step 4-3-2, detecting the active users and data of the subsystem to be detected, and updating the subsystem I g+1 Estimation matrix of user data->
Figure FDA0004233201800000097
The detected subsystem is not repeatedly detected; until the iteration number reaches g > N b When the joint detection of the active user and the data is finished, an estimation matrix of the system user data is obtained
Figure FDA0004233201800000098
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