CN-117081901-B - Layered orthogonal amplitude modulation multiple access method without serial interference cancellation

CN117081901BCN 117081901 BCN117081901 BCN 117081901BCN-117081901-B

Abstract

The invention discloses a layering quadrature amplitude modulation multiple access method without serial interference cancellation, which maps user bits to constellation points of different levels, sets Euclidean distance between constellation points in each level according to channel gain of users, namely adjusts power of each level of users, finally forms layering constellation points to bear bits of multiple users after layering the layering constellation points are overlapped, sets a plurality of working configuration points on the basis, selects one or a plurality of working configuration points according to the number of users in current transmission and the rate requirement required by the users to finish transmission tasks, and sends Euclidean distance between constellation points and corresponding origins in each level in a complete constellation diagram of each user in constellation point mapping bit strings to a receiver through a transmitter, and if the plurality of working configuration points are selected, the users can reach the maximum capacity boundary of downlink multi-user transmission service without serial interference cancellation.

Inventors

ZHAO MING
ZHU JINKANG

Assignees

中国科学技术大学

Dates

Publication Date: 20260508
Application Date: 20230925

Claims (10)

1. A layered quadrature amplitude modulation multiple access method without serial interference cancellation, comprising: Decoupling the maximum constellation point number which can be borne into two parts, and mapping the two parts on an I path and a Q path respectively; Respectively carrying out bit mapping on the I path and the Q path, distributing the bits carried by the I path and the Q path to users, mapping the bits distributed to the users to constellation points of different levels, setting Euclidean distances between the constellation points in each level and corresponding origins according to the channel gain of the users, namely, the power of each level user, and finally, superposing the multi-level constellation points to form a hierarchical constellation point to carry the bits of multiple users; Setting a plurality of working configuration points based on Euclidean distance between constellation points and corresponding origins in each level in the complete constellation diagram, wherein each working configuration point corresponds to different user channel gains and receiving signal-to-noise ratios and can meet the rate requirements of different users, selecting the corresponding working configuration point according to the number of the users and the rate required by the users to perform information transmission work, transmitting bit positions of each user in a constellation point mapping bit string, euclidean distance between constellation points and corresponding origins in each level in the complete constellation diagram to a receiving side through a transmitter, and transmitting working configuration point proportion information if a plurality of working configuration points are selected; And receiving constellation points obtained by a user according to the amplitude and the phase of the channel, mapping the constellation points to an I axis and a Q axis respectively to obtain corresponding I-path signals and Q-path signals, and carrying out decoding operation by combining Euclidean distance information between the constellation points and corresponding origins in each level in the complete constellation diagram and bit position and working configuration point proportioning information of the user in a bit string.
2. The hierarchical ofdma method as set forth in claim 1 wherein decoupling the maximum number of constellation points that can be carried into two parts and mapping each on I and Q paths comprises: The maximum constellation point number which can be borne is recorded as M, and the maximum constellation point number is decoupled into two parts and expressed as M=2 m ·2 n , wherein 2 m constellation points are mapped on an I path, 2 n constellation points are mapped on a Q path, namely the I path bears M bits and is distributed to M users at most, and the Q path bears n bits and is distributed to n users at most.
3. A layered orthogonal amplitude modulation multiple access method without serial interference cancellation according to claim 1 or 2, characterized in that, The euclidean distance between the constellation points in each level in the I-way and the corresponding origin is expressed as: Wherein d i is a set of euclidean distances between constellation points and corresponding origins in all levels in the I-path, each term is the euclidean distance between a constellation point and a corresponding origin in one level, the upper index I represents the I-path, the lower index value is the sequence number of the level, and m is the number of bits that the I-path can carry and also corresponds to the highest level; the euclidean distance between the constellation points in each level in the Q-way and the corresponding origin is expressed as: Wherein d q is a set of euclidean distances between constellation points and corresponding origins in all levels in the Q-way, each term is the euclidean distance between a constellation point and a corresponding origin in one level, the superscript Q represents the Q-way, the subscript value is the sequence number of the level, and n is the number of bits that the Q-way can bear and also corresponds to the highest level; all Euclidean distances of the I path and the Q path meet and the power is constant, and the method is expressed as: E s ＝||d i || 2 +||d q || 2 Wherein E s is the total power.
4. The hierarchical ofdma method of claim 1 wherein the mapping bits allocated to users to constellation points at different levels and setting euclidean distances between constellation points and corresponding origins within each level according to the channel gain of the users comprises: determining the number of layers according to the decoupled information, determining the mapped layers according to the user channel gain, wherein the lower the layers are, the larger the Euclidean distance between constellation points in the layers and the corresponding origin is, and then adjusting the Euclidean distance between the constellation points in each layer and the corresponding origin according to the user channel gain.
5. A method according to claim 1, wherein no serial interference is required a method of cancellation of layered quadrature amplitude modulation multiple access, the method is characterized in that Gray mapping mode is adopted when bit mapping is carried out on the I path and the Q path respectively.
6. The method of claim 1, wherein the set plurality of working configuration points are { p 0 ,p 1 ,...,p L }, each of which is one working configuration point, L is the maximum number of the working configuration points, each working configuration point has the Euclidean distance between the constellation point and the corresponding origin in each level of the corresponding complete constellation, the corresponding working configuration point is selected according to the number of users and the rate required by the users, and the time-frequency resource occupation ratio of the working configuration point, namely the ratio information of the working configuration points, is set by combining the rate requirements of the users.
7. The hierarchical ofdma method as set forth in claim 6 wherein the plurality of operating configuration points are set in the following manner: Based on Euclidean distance between constellation points and corresponding origins in each level in the complete constellation diagram, when the number of bearing users is 2, two working configuration points p 0 and p L are arranged, all bits corresponding to the respective exclusive constellation point mapping bit strings of the two users are naturally determined according to channel gain and signal to noise ratio, on a multi-user rate interval diagram, the rest working configuration points are required to be far away from a connecting line between p 0 and p L , so that the connecting line of all the working configuration points forms a most convex envelope, namely the area surrounded by the envelope and a transverse axis is the largest, when the number of bearing users is 3, 3 single users are arranged to monopolize all the working configuration points of bits, the 3 working configuration points are naturally determined according to channel gain and signal to noise ratio, the 3 working configuration points form a plane on a three-dimensional space, and the connection of the rest working configuration points selected by subsequent optimization is formed into a most convex approximate curved surface, and when the number of bearing users is more than 3, the working configuration points are sequentially analogized to a high-dimensional space.
8. The hierarchical ofdma method of claim 1 wherein receiving the user's decoding operation in combination with the euclidean distance information between the constellation points in each level in the complete constellation and the corresponding origin, the bit positions of the user in the bit string, and the working configuration point matching information comprises: The signal processing processes of the I path and the Q path are the same, and for the current receiving side user, the obtained I path signal y is expressed as: Wherein G is the channel power gain of the current receiving side user, s is the normalized effective signal, and eta is noise; Each receiving user respectively decodes the obtained I-path and Q-path signals according to the mapping position information in the bit string, the Euclidean distance information between the constellation points in each level in the complete constellation diagram and the corresponding original points and the proportion information of the working configuration points to obtain the likelihood values of the bits, and then carries out decoding judgment of the error correction codes at the back end, wherein the working configuration points where each resource unit in the current transmission signal is positioned are determined based on the proportion information of the working configuration points, then Euclidean distance information between the constellation points in each level in the complete constellation diagram corresponding to the corresponding working configuration points and the corresponding original points is adopted, and the likelihood values of the bits corresponding to each bit position are calculated by combining the I-path and Q-path signals obtained by the corresponding resource units.
9. The hierarchical ofdma method as set forth in claim 8 wherein the likelihood value Λ (b κ ) of bit b κ is expressed as: Where the subscript k is bit position information, b κ is the bit at the k position, oc represents proportional to σ 2 ＝N 0 /2, is the variance of the noise fraction, N 0 is the noise power spectral density, and z κ represents the likelihood of bit b κ without regard to the channel gain and noise power.
10. The hierarchical ofdma method as set forth in claim 9 wherein z κ is calculated as follows: Z 1 ＝d 1 y when there is only one layer of user bits; When the number of levels of the layered constellation points is 2: When the number of levels of the layered constellation points is 3: Wherein d 1 、d 2 、d 3 sequentially represents the Euclidean distance between the constellation points in the 1 st level, the 2 nd level and the 3 rd level in one path and the corresponding origin.

Description

Layered orthogonal amplitude modulation multiple access method without serial interference cancellation Technical Field The invention relates to the technical field of wireless communication, in particular to a layered orthogonal amplitude modulation multiple access method without serial interference cancellation. Background When a base station provides a downlink transmission service for a plurality of users, a radio spectrum is generally divided into time-frequency resource blocks and allocated to the plurality of users for use. Such techniques are collectively referred to as downstream multiple access techniques. Existing downlink multiple access techniques are divided into two categories, orthogonal multiple access techniques and non-orthogonal multiple access techniques. Orthogonal multiple access refers to allocating different resource units (time-frequency resource blocks) to different users, and non-orthogonal multiple access refers to allocating the same resource unit to multiple users for simultaneous use. The implementation of non-orthogonal multiple access techniques is largely extended from both the power domain and the code domain. Several key implementations of downlink multi-user overlapping transmission (hereinafter referred to as the mud technique) have been specified in the 3gpp tr36.859 protocol (3GPP TR 36.859V13.0.0(2015-12),"Technical Specification Group Radio Access Network;Study on Downlink Multiuser Superposition Transmission(MUST)for LTE(Release 13),"Dec.2015.). The mud technique specifies the constellation mapping method employed in multi-user signal transmission. In the methods, a plurality of users with different channel gains form a transmitting group, and the users in the group adopt respective constellation mapping and are overlapped after being configured with different powers, or the users are subjected to bit mapping on a unified constellation diagram. Each of these methods modulates on both I/Q branches simultaneously and applies the same power scaling factor on the I/Q branches. Meanwhile, on the receiving side, the serial interference cancellation technology is a necessary receiving technology, namely, users with better channel conditions in a group need to firstly solve the user information with worse channel conditions and reconstruct the signals thereof, and cancel the signals in the received signals, thereby receiving the signals of the users. But this approach increases the complexity of reception under non-orthogonal reception conditions. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a layered orthogonal amplitude modulation multiple access method without serial interference cancellation, which belongs to the class of non-orthogonal multiple access, and can lead a receiving user not to carry out serial interference cancellation, thereby reducing the receiving complexity under the non-orthogonal receiving condition, reaching the capacity limit as that when MUST adopts serial interference cancellation, and easily realizing the non-orthogonal access of 2 or more users. The invention aims at realizing the following technical scheme: a layered quadrature amplitude modulation multiple access method without serial interference cancellation, comprising: Decoupling the maximum constellation point number which can be borne into two parts, and mapping the two parts on an I path and a Q path respectively; Respectively carrying out bit mapping on the I path and the Q path, distributing the bits carried by the I path and the Q path to users, mapping the bits distributed to the users to constellation points of different levels, setting Euclidean distances between the constellation points in each level and corresponding origins according to the channel gain of the users, namely, the power of each level user, and finally, superposing the multi-level constellation points to form a hierarchical constellation point to carry the bits of multiple users; Setting a plurality of working configuration points based on Euclidean distance between constellation points and corresponding origins in each level in the complete constellation diagram, wherein each working configuration point corresponds to different user channel gains and receiving signal-to-noise ratios and can meet the rate requirements of different users, selecting the corresponding working configuration point according to the number of the users and the rate required by the users to perform information transmission work, transmitting bit positions of each user in a constellation point mapping bit string, euclidean distance between constellation points and corresponding origins in each level in the complete constellation diagram to a receiving side through a transmitter, and transmitting working configuration point proportion information if a plurality of working configuration points are selected; And receiving constellation points obtained by a user according to the