WO2016065921A1 - 多用户信息传输的叠加、解调方法及装置 - Google Patents

多用户信息传输的叠加、解调方法及装置 Download PDF

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WO2016065921A1
WO2016065921A1 PCT/CN2015/083474 CN2015083474W WO2016065921A1 WO 2016065921 A1 WO2016065921 A1 WO 2016065921A1 CN 2015083474 W CN2015083474 W CN 2015083474W WO 2016065921 A1 WO2016065921 A1 WO 2016065921A1
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symbol sequence
complex symbol
complex
signal
user
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PCT/CN2015/083474
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English (en)
French (fr)
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袁志锋
戴建强
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中兴通讯股份有限公司
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Priority to EP15854456.9A priority Critical patent/EP3214783B1/en
Priority to JP2017522858A priority patent/JP6692807B2/ja
Priority to US15/522,492 priority patent/US10097386B2/en
Priority to KR1020177013422A priority patent/KR102371842B1/ko
Publication of WO2016065921A1 publication Critical patent/WO2016065921A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H04L27/04—Modulator circuits; Transmitter circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • 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
    • H04L27/2602—Signal structure
    • H04L27/2604—Multiresolution systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • 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
    • H04L5/0037—Inter-user or inter-terminal allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3488—Multiresolution systems

Definitions

  • the present invention relates to the field of communications, and in particular to a method and apparatus for superimposing and demodulating multi-user information transmission.
  • Multi-user information transmission technology can be divided into Orthogonal Multiple Access (OMA) and Non-Orthogonal Multiple Access (NOMA).
  • OMA Orthogonal Multiple Access
  • NOMA Non-Orthogonal Multiple Access
  • Traditional TDMA, orthogonal CDMA, and OFDMA are all in the category of orthogonal multiple access multiplexing.
  • orthogonal multiple access multiplexing technique each user uses a strictly "sub-channel" that is mutually orthogonal to communicate, so that there is no mutual interference between user information during demodulation, and thus it is easier to separate user information.
  • each user's information is transmitted on the “whole channel”, and each user information interferes with each other during demodulation, so it is troublesome to separate user information. .
  • Non-orthogonal multiple access multiplexing techniques can generally be divided into two demodulation methods:
  • each user is demodulated with the interference of other users, which is simpler to implement, but the performance is detrimental.
  • the second is to use interference cancellation technology, that is, multi-user detection technology.
  • the multi-user SIC process can be easily promoted by first demodulating and decoding the user A information. User B's interference to demodulate the decoded A information). Then, when demodulating the user B information, it is necessary to first demodulate the previously demodulated A information (which may need to be reconstructed), and then demodulate the user B information. In this way, the user B information can be greatly improved because there can be no interference.
  • the adoption of non-orthogonal multiple access multiplexing combined with SIC technology in the related art can achieve the limit of multi-user information capacity.
  • FIG. 1 is a schematic diagram of a NOMA downlink broadcast according to the related art.
  • downlink multi-user information transmission is also commonly referred to as downlink broadcast, which means that the transmitter can transmit the respective required information to multiple receivers in a non-orthogonal manner.
  • multi-user multiple access “broadcast” refers to information of different users. It is sent out by the base station, and the base station in the conventional broadcast (for example, radio broadcast) is different in sending the same information to all users.
  • FIG. 2 is a schematic diagram of capacity comparison of the NOMA method and the OMA method according to the related art.
  • the downlink multi-user information transmission technology has two access modes: non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA).
  • NOMA non-orthogonal multiple access
  • OMA orthogonal multiple access
  • the NOMA approach enables greater system capacity or edge throughput than the OMA approach because each user can use all degrees of freedom.
  • the NOMA downlink broadcast can increase the capacity of edge users more preferentially while substantially maintaining the high throughput of the center users.
  • the signals of multiple users are superimposed together and then transmitted on the same time-frequency resource.
  • the process of superimposing multiple user signals is also referred to as "superimposition coding.”
  • the direct addition of multiple user signals is one of the simplest "superimposition coding", and this simplest direct addition superposition coding method combined with the code block level SIC can also achieve the downlink multi-user channel capacity limit.
  • this simplest direct addition of the superposition coding method is due to the fact that the constellation points that are finally combined have no Gray mapping (the mapping of adjacent constellation points has only one bit difference, so the performance of the modulation is optimal).
  • 3 is a schematic diagram of direct superimposition coding of a plurality of user signals according to the related art. As shown in FIG. 3, it is a constellation in which QPSK symbols and QPSK symbols are directly superimposed. If the terminal uses simple symbol-level SIC reception, its demodulation performance will drop greatly. Therefore, in order to ensure performance, the terminal needs to use a complex code-block-level SIC.
  • the block-level SIC can cause high implementation complexity, power consumption, and latency for the terminal, which is sometimes unacceptable to the terminal.
  • Hierarchical modulation can also be seen as a variant of superposition coding.
  • Hierarchical modulation refers to the formation of superimposed modulation symbols by a combination of a high priority bit stream and a low priority bit stream.
  • layered modulation can also combine constellations with Gray mapping attributes, hierarchical modulation is not flexible for different power allocations of different data streams, and its implementation complexity is also high. Different power allocations for different data streams are necessary to achieve downlink multi-user channel capacity.
  • Embodiments of the present invention provide a method and apparatus for superimposing and demodulating multi-user information transmission, so as to at least solve the problem that a plurality of user signals in the related art are directly added and the constellation points that are finally combined have no Gray mapping attribute.
  • a superposition method of multi-user information transmission is provided.
  • a method for superimposing multi-user information transmission includes: separately modulating two bit information streams into a first complex symbol sequence and a second complex symbol sequence; and superimposing the first complex symbol sequence and the second complex symbol sequence Processing, generating a third complex symbol sequence, wherein the third complex symbol sequence has a Gray mapping attribute; forming a transmission signal according to the third complex symbol sequence, and transmitting the transmission signal to the plurality of receivers.
  • separately modulating the two bit information streams into the first complex symbol sequence and the second complex symbol sequence comprises: normalizing the power of the first information stream in the two bit information streams by power normalized constellation modulation Multiplying the modulation symbol sequence by the first power adjustment factor to obtain the first complex symbol sequence; multiplying the second information stream in the two bit information streams by the power normalized constellation modulated power-normalized modulation symbol sequence by the first
  • the second power adjustment factor obtains a second complex symbol sequence; wherein, the length of the first complex symbol sequence includes: 1, the length of the second complex symbol sequence includes: 1, the first power adjustment factor is greater than the second power adjustment factor, and the first complex number
  • the modulation order of the symbol sequence is lower than or equal to the modulation order of the second complex symbol sequence.
  • the first complex symbol sequence and the second complex symbol sequence are superimposed, and the generating the third complex symbol sequence comprises: changing the amplitude of the second complex symbol sequence in the complex plane according to the first complex symbol sequence, and the amplitude remains unchanged Obtaining the changed symbol sequence; superimposing the first complex symbol sequence and the changed symbol sequence to generate a third complex symbol sequence.
  • the first complex symbol sequence is superimposed with the changed symbol sequence
  • the third complex symbol sequence is generated to include one of the following: the third complex symbol sequence is The third complex symbol sequence is among them, For the first complex symbol sequence, For the second complex symbol sequence, or For the changed symbol sequence, Xstd+Ystd ⁇ i is an unnormalized integer lattice constellation symbol corresponding to the first complex symbol sequence, including: BPSS corresponding X std takes the value ⁇ 1, -1 ⁇ , Ystd Take the zero; QSTK corresponds to X std and Y std as ⁇ 1, -1 ⁇ ; 16QAM corresponds to X std and Y std as ⁇ 1, -1, 3, -3 ⁇ ; 64QAM corresponds to X std , Y std takes the values ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ ; For the first power adjustment factor, For the second power adjustment factor, Indicates rounding up,
  • the method further comprises: adjusting the third complex symbol sequence by adjusting the first power adjustment factor and/or the second power adjustment factor; or by adjusting the first power adjustment factor and/or Or the second power adjustment factor adjusts the constellation map of the third complex symbol sequence mapping.
  • the method before separately modulating the two bit information streams into the first complex symbol sequence and the second complex symbol sequence, the method further includes: encoding the two user information streams according to the channel condition to determine the code modulation mode, and generating two bits.
  • the information flow wherein the protection priority of the first user information flow in the two user information is greater than the protection priority of the second user information flow in the two user information.
  • a demodulation method for multi-user information transmission is provided.
  • a demodulation method for multi-user information transmission includes: receiving a transmission signal from a transmitter, wherein the transmission signal is modulating a two-bit information stream into a first complex symbol sequence and a second at a transmitter, respectively a complex symbol sequence, and after the first complex symbol sequence and the second complex symbol sequence are superimposed to generate a third complex symbol sequence, the third complex symbol sequence is formed according to the third complex symbol sequence, and the third complex symbol sequence has a Gray mapping attribute;
  • the received signal is demodulated by a corresponding demodulation method.
  • demodulating the received signal by using a corresponding demodulation manner according to the type of the self includes demodulating the user to be sent to the cell edge directly from the received signal carrying the interference signal when determining that the type is the cell edge user.
  • the first part of the signal; the user information corresponding to the cell edge user is decoded from the first part of the signal.
  • demodulating the received signal by using a corresponding demodulation manner according to the type of the self includes demodulating the user to be sent to the cell edge directly from the received signal carrying the interference signal when determining that the type is the cell center user. a first part of the signal; removing the first part of the received signal, and demodulating the second part of the signal to be sent to the user of the cell center from the remaining part of the signal; changing the second part of the signal in the complex plane according to the first part of the signal The amplitude of the amplitude remains unchanged, and the changed second partial signal is obtained; the user information corresponding to the cell center user is decoded from the changed second partial signal.
  • the time-frequency resources of the channels used by each user to receive the transmitted signals are the same and overlapped.
  • a superimposing apparatus for multi-user information transmission is provided.
  • the superimposing apparatus for multi-user information transmission includes: a modulation module configured to separately modulate two bit information streams into a first complex symbol sequence and a second complex symbol sequence; and the superimposing module is configured to adopt the first complex number
  • the symbol sequence is superimposed with the second complex symbol sequence to generate a third complex symbol sequence,
  • the third complex symbol sequence has a Gray mapping attribute;
  • the transmitting module is configured to form a transmission signal according to the third complex symbol sequence and transmit the transmission signal to the plurality of receivers.
  • the modulating module comprises: a first modulating unit configured to multiply the first information stream in the two bit information streams by the power normalized constellation modulated power normalized modulation symbol sequence by the first power adjustment factor Obtaining a first complex symbol sequence; the second modulation unit is configured to multiply the second information stream in the two bit information streams by the power normalized constellation modulated power-normalized modulation symbol sequence by the second power adjustment factor Obtaining a second complex symbol sequence; wherein the length of the first complex symbol sequence comprises: 1, the length of the second complex symbol sequence comprises: 1, the first power adjustment factor is greater than the second power adjustment factor, and the modulation of the first complex symbol sequence The order is lower than or equal to the modulation order of the second complex symbol sequence.
  • the superimposing module comprises: an acquiring unit, configured to change the amplitude of the second complex symbol sequence in the complex plane according to the first complex symbol sequence, the amplitude remains unchanged, and obtain the changed symbol sequence; the superimposing unit is set to be A complex symbol sequence is superimposed with the changed symbol sequence to generate a third complex symbol sequence.
  • the obtaining unit comprises: a first acquiring subunit, configured to determine a real part symbol of the changed symbol sequence according to a real part value of the first complex symbol sequence; and a second acquiring subunit, configured to be according to the first complex symbol
  • the imaginary part of the sequence takes the imaginary part of the changed symbol sequence.
  • the coding unit is configured to perform a superposition process on the first complex symbol sequence and the changed symbol sequence, and generate a third complex symbol sequence including one of: the third complex symbol sequence is The third complex symbol sequence is among them, For the first complex symbol sequence, For the second complex symbol sequence, or For the changed symbol sequence, Xstd+Ystd ⁇ i is an unnormalized integer lattice constellation symbol corresponding to the first complex symbol sequence, including: BPSS corresponding X std takes the value ⁇ 1, -1 ⁇ , Ystd Take the zero; QSTK corresponds to X std and Y std as ⁇ 1, -1 ⁇ ; 16QAM corresponds to X std and Y std as ⁇ 1, -1, 3, -3 ⁇ ; 64QAM corresponds to X std , Y std takes the values ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ ; For the first power adjustment factor, For the second power adjustment factor
  • the apparatus further includes: an adjustment module configured to adjust the third complex symbol sequence by adjusting the first power adjustment factor and/or the second power adjustment factor; or by adjusting the first power adjustment factor and/or The second power adjustment factor adjusts the constellation map of the third complex symbol sequence mapping.
  • an adjustment module configured to adjust the third complex symbol sequence by adjusting the first power adjustment factor and/or the second power adjustment factor; or by adjusting the first power adjustment factor and/or The second power adjustment factor adjusts the constellation map of the third complex symbol sequence mapping.
  • the apparatus further includes: a generating module, configured to determine, according to a channel condition, a coded modulation mode to encode two user information streams to generate two bit information streams, wherein the first user information stream of the two user information The protection priority is greater than the protection priority of the second user information flow in the two user information.
  • a generating module configured to determine, according to a channel condition, a coded modulation mode to encode two user information streams to generate two bit information streams, wherein the first user information stream of the two user information The protection priority is greater than the protection priority of the second user information flow in the two user information.
  • a demodulation apparatus for multi-user information transmission is provided.
  • a demodulation apparatus for multi-user information transmission includes: a receiving module configured to receive a transmission signal from a transmitter, wherein the transmission signal is separately modulated into a first complex number on the transmitter by two bit information streams a symbol sequence and a second complex symbol sequence, and after the first complex symbol sequence and the second complex symbol sequence are superimposed to generate a third complex symbol sequence, the third complex symbol sequence is formed according to the third complex symbol sequence, and the third complex symbol sequence has a Gray mapping Attribute; the demodulation module is configured to demodulate the received signal according to its own type by using a corresponding demodulation method.
  • the demodulation module comprises: a first demodulation unit configured to directly demodulate the first part of the signal to be sent to the user of the cell edge from the received signal carrying the interference signal if the type of the user is determined to be a cell edge user
  • the first decoding unit is configured to decode the user information corresponding to the cell edge user from the first partial signal.
  • the demodulation module comprises: a second demodulation unit configured to directly demodulate the first part of the signal to be sent to the user of the cell edge from the received signal carrying the interference signal in the case that the self type is determined to be the cell center user a third demodulation unit configured to remove the first portion of the received signal and demodulate the second portion of the signal to be transmitted to the center user of the cell from the remaining portion of the signal; the processing unit is configured to be based on the first portion The signal changes the amplitude of the second partial signal in the complex plane, the amplitude remains unchanged, and the changed second partial signal is obtained; and the second decoding unit is configured to decode the second partial signal corresponding to the cell center user User information.
  • the time-frequency resources of the channels used by each user to receive the transmitted signals are the same and overlapped.
  • two bit information streams are separately modulated into a first complex symbol sequence and a second complex symbol sequence; and the first complex symbol sequence and the second complex symbol sequence are superimposed to generate a third complex symbol sequence.
  • the third complex symbol sequence has a Gray mapping attribute; the transmitting signal is formed according to the third complex symbol sequence, and the transmitting signal is sent to the plurality of receivers, and the multiple user signals in the related art are directly added and finally combined.
  • the constellation point has no problem of Gray mapping attribute, and the SIC receiver is simplified in the NOMA downlink broadcast communication system, so that the receiving end performs symbol level SIC demodulation as much as possible, and at the same time, the superimposed symbol has the Gray attribute again, and It is simple and flexible to allocate different powers for different data streams and improve the performance of multiple access.
  • FIG. 1 is a schematic diagram of a NOMA downlink broadcast according to the related art
  • FIG. 2 is a schematic diagram of capacity comparison of a NOMA method and an OMA method according to the related art
  • FIG. 3 is a schematic diagram of direct superposition of a plurality of user signals according to the related art
  • FIG. 5 is a flowchart of a demodulation method for multi-user information transmission according to an embodiment of the present invention
  • FIG. 6 is a schematic diagram of a wireless broadcast communication system implemented by a superposition method of a downlink multi-user information transmission system according to a preferred embodiment of the present invention
  • FIG. 7 is a schematic diagram showing the structure of an exemplary receiver of a downlink multi-user information transmission system according to a preferred embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a superimposing apparatus of a downlink multi-user information transmission system according to a preferred embodiment of the present invention.
  • FIG. 9 is a schematic structural diagram of a transmitter module of a superimposing apparatus of a downlink multi-user information transmission system according to a preferred embodiment of the present invention.
  • FIG. 10 is a schematic diagram of a process of changing a QPSK signal of a center user according to a preferred embodiment of the present invention
  • FIG. 11 is a schematic diagram of a superimposition process that remains unchanged after a change process, in accordance with a preferred embodiment of the present invention.
  • FIG. 12 is a schematic diagram of a superimposition process of performing horizontal mapping after a change process according to a preferred embodiment of the present invention
  • FIG. 13 is a schematic diagram of a process of changing a 16QAM signal of a center user according to a preferred embodiment of the present invention
  • FIG. 14 is a structural block diagram of a superimposing apparatus for multi-user information transmission according to an embodiment of the present invention.
  • FIG. 15 is a structural block diagram of a superimposing apparatus for multi-user information transmission according to a preferred embodiment of the present invention.
  • 16 is a block diagram showing the structure of a demodulation apparatus for multi-user information transmission according to an embodiment of the present invention.
  • Figure 17 is a block diagram showing the structure of a demodulation apparatus for multi-user information transmission in accordance with a preferred embodiment of the present invention.
  • FIG. 4 is a flow chart of a method of superimposing multi-user information transmission according to an embodiment of the present invention. As shown in FIG. 4, the method may include the following processing steps:
  • Step S402 modulating two bit information streams into a first complex symbol sequence and a second complex symbol sequence, respectively;
  • Step S404 Perform a superposition process on the first complex symbol sequence and the second complex symbol sequence to generate a third complex symbol sequence, where the third complex symbol sequence has a Gray mapping attribute;
  • Step S406 Form a transmission signal according to the third complex symbol sequence, and transmit the transmission signal to a plurality of receivers.
  • the multiple user signals in the related art are directly added and the constellation points that are finally combined have no Gray mapping attribute.
  • the transmitter can perform the corresponding change processing on the constellation of the central user, and then perform superposition processing, and then the superposed symbols form a transmission signal, which is sent to the receiver at the inner edge of the cell and received by the central user. machine. Therefore, for the NOMA downlink broadcast system, not only can the receiver perform SIC demodulation at the symbol level, but also greatly simplify the SIC receiver, and also enable the superimposed symbols to have the Gray attribute, and can be implemented simply and flexibly. Different data streams allocate different powers, improve the performance of multiple access, and especially improve the performance of the cell center users.
  • the superposition scheme of the downlink multi-user information transmission system provided by the embodiment of the present invention can support the old version of the downlink broadcast system.
  • separately modulating the two bit information streams into the first complex symbol sequence and the second complex symbol sequence may comprise the following operations:
  • Step S1 Multiplying the first information stream in the two bit information streams by the power normalized constellation-modulated power-normalized modulation symbol sequence by the first power adjustment factor to obtain the first complex symbol sequence;
  • Step S2 multiplying the second information stream in the two bit information streams by the power normalized constellation-modulated power-normalized modulation symbol sequence by the second power adjustment factor to obtain the second complex symbol sequence;
  • the length of the first complex symbol sequence includes: 1.
  • the length of the second complex symbol sequence includes: 1.
  • the first power adjustment factor is greater than the second power adjustment factor, and the modulation order of the first complex symbol sequence is lower than or equal to the first The modulation order of the sequence of two complex symbols.
  • the complex symbol sequence S1 is obtained by multiplying C1 by a power normalized constellation modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the complex symbol sequence S2 is obtained by multiplying C2 by a power normalized constellation-modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the complex symbol sequence S1 with a certain power after C1 modulation is The complex symbol sequence S2 with a certain power after C2 modulation is The power adjustment factor of S1 is The power adjustment factor of S2 is more than the when less than or equal to There is no need to make a constellation change to the symbol sequence S2.
  • step S404 the first complex symbol sequence and the second complex symbol sequence are used for superposition processing, and the generating the third complex symbol sequence may include the following steps:
  • Step S3 changing the amplitude of the second complex symbol sequence in the complex plane according to the first complex symbol sequence, the amplitude remains unchanged, and acquiring the changed symbol sequence;
  • Step S4 superimposing the first complex symbol sequence and the changed symbol sequence to generate a third complex symbol sequence.
  • the complex symbol sequence S1 and S2 may be directly superimposed by the complex symbol sequence S1 and the complex symbol sequence S2 after the superposition, and the directly superposed complex symbol sequence S3 may be represented as (S1+S).
  • the changed symbols of S1 and S2 are directly superimposed to obtain S3.
  • the constellation points of S3 have the Gray attribute, and the superimposed symbol constellation can have the Gray attribute by other methods.
  • step S3 changing the second complex symbol sequence, obtaining the changed symbol sequence may include an operation:
  • Step S31 determining a real part symbol of the changed symbol sequence according to a real part value of the first complex symbol sequence
  • Step S32 Determine an imaginary part symbol of the changed symbol sequence according to the imaginary part of the first complex symbol sequence.
  • the change process is required before the complex symbol sequence S2 and S1 are superimposed, the sign of the real part of S is determined according to the value of the real part of S1, and the sign of the imaginary part is determined according to the value of the imaginary part of S1.
  • the complex symbol S of the sequence S2 can be expressed as: or The power of the symbol S is the same as the power of the S2.
  • step S4 the first complex symbol sequence and the changed symbol sequence are superimposed to generate a third complex symbol sequence, which may include one of the following ways:
  • Xstd+Ystd ⁇ i is an unnormalized integer lattice constellation symbol corresponding to the first complex symbol sequence, including: BPSS corresponding X std takes the value ⁇ 1, -1 ⁇ , Ystd Take the zero; QSTK corresponds to X std and Y std as ⁇ 1, -1 ⁇ ; 16QAM corresponds to X std and Y std as ⁇ 1, -1, 3, -3 ⁇ ; 64QAM corresponds to X std , Y std takes the values ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ ; For the first power adjustment factor, For the second power adjustment factor, Indicates rounding up, Indicates rounding down.
  • the complex symbol sequence S1 having a certain power after C1 modulation is The complex symbol sequence S2 with a certain power after C2 modulation is The unnormalized integer lattice constellation symbol S std corresponding to S1 is Xstd+Ystd ⁇ i, and then S1 and S2 are superimposed and changed to obtain a complex symbol sequence S3. Power adjustment factor, symbol Indicates rounding up.
  • the unnormalized integer lattice constellation symbol S std is Xstd+Ystd ⁇ i.
  • Xstd and Ystd corresponding to QPSK are ⁇ 1, -1 ⁇
  • Xstd and Ystd corresponding to 16QAM are ⁇ 1, - 1,3,-3 ⁇
  • Xstd and Ystd corresponding to 64QAM take values of ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ .
  • the complex symbol sequence S1 with a certain power after C1 modulation is The complex symbol sequence S2 with a certain power after C2 modulation is The unnormalized integer lattice constellation symbol S std corresponding to S1 is Xstd+Ystd ⁇ i, and then S1 and S2 are superimposed and changed to obtain a complex symbol sequence S3. Power adjustment factor, symbol Indicates rounding down.
  • the unnormalized integer lattice constellation symbol S std is Xstd+Ystd ⁇ i.
  • Xstd and Ystd corresponding to QPSK are ⁇ 1, -1 ⁇
  • Xstd and Ystd corresponding to 16QAM are ⁇ 1, - 1,3,-3 ⁇
  • Xstd and Ystd corresponding to 64QAM take values of ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ .
  • step S404 the third complex symbol sequence is generated, and may further include the following operations:
  • the power adjustment factor can be Adjust S3, where more than the
  • step S402 Before the two bit information streams are respectively modulated into the first complex symbol sequence and the second complex symbol sequence in step S402, the following steps may be further included:
  • Step S6 determining, according to the channel condition, the coding and modulation mode, encoding the two user information streams, and generating two bit information streams, wherein the protection priority of the first user information stream in the two user information is greater than the two user information. The protection priority of the second user information stream.
  • the two bit information streams can be encoded by a dual information bit stream, wherein the C1 protection priority is greater than the protection priority of C2.
  • C1 and C2 are modulated into complex symbol sequences S1 and S2 having a certain power, and the modulation order of S1 is lower than or equal to the modulation order of S2.
  • S1 and S2 are superimposed to obtain modulation symbols higher than the S1 or S2 modulation order.
  • FIG. 5 is a flowchart of a demodulation method of multi-user information transmission according to an embodiment of the present invention. As shown in FIG. 5, the method may include the following processing steps:
  • Step S502 Receive a transmission signal from a transmitter, where the transmission signal is a modulation of the two bit information streams into a first complex symbol sequence and a second complex symbol sequence on the transmitter, and adopts the first complex symbol sequence and the first After the second complex symbol sequence is subjected to superposition processing to generate a third complex symbol sequence, the third complex symbol sequence is formed according to the third complex symbol sequence, and the third complex symbol sequence has a Gray mapping attribute;
  • Step S504 Demodulate the received signal by using a corresponding demodulation method according to its own type.
  • the method shown in FIG. 5 solves the problem that the plurality of user signals in the related art are directly added and the final combined constellation points have no Gray mapping attribute, thereby simplifying the SIC receiver in the NOMA downlink broadcast communication system.
  • the receiving end performs the symbol level SIC demodulation as much as possible, and at the same time, the superimposed symbols have the Gray attribute, and the different powers can be allocated to different data streams in a simple and flexible manner, thereby improving the multiple access performance.
  • step S504 demodulating the received signal according to its own type by using a corresponding demodulation manner may include the following operations:
  • Step S7 When determining that the type of the user is a cell edge user, directly demodulate the first part of the signal to be sent to the cell edge user from the received signal carrying the interference signal;
  • Step S8 Decoding user information corresponding to the cell edge user from the first partial signal.
  • the edge user receiver 1 in the cell demodulates the edge user information with the interference of the center user.
  • step S504 demodulating the received signal according to its own type by using a corresponding demodulation manner may include the following steps:
  • Step S9 When determining that the type of the user is a cell center user, directly demodulate the first part of the signal to be sent to the user of the cell edge from the received signal carrying the interference signal;
  • Step S10 removing the first part of the signal in the received signal, and demodulating the second part of the signal to be sent to the user of the cell center from the remaining part of the signal;
  • Step S11 changing the amplitude of the second partial signal in the complex plane according to the first partial signal, the amplitude remains unchanged, and obtaining the changed second partial signal;
  • Step S12 Decoding the user information corresponding to the cell center user from the changed second partial signal.
  • the central user receiver 2 in the cell changes the decoded central user information after demodulating the edge user information and removing it.
  • the time-frequency resources of the channels used by each user to receive the transmitted signals are the same and overlapped.
  • Each user's information is transmitted on the "full channel".
  • the entire channel refers to the same time-frequency resources of multiple channels, and can be completely overlapped.
  • the receiving end demodulates the edge user's information S1' as x1'+y1' ⁇ i
  • the central user receiver 2 in the cell demodulates the edge user information and removes the signal as x2'+y2.
  • S1' corresponds to the standard unnormalized integer lattice constellation symbol S std ' is Xstd' + Ystd' ⁇ i then undergoes change processing to demodulate the central user signal can be or Among them, the symbol Indicates rounding up, Indicates rounding down.
  • the unnormalized integer lattice constellation symbol S std ' is Xstd'+Ystd' ⁇ i, for example, Xstd' and Ystd' corresponding to QPSK are ⁇ 1, -1 ⁇ ; for example, Xstd', Ystd corresponding to 16QAM 'The value is ⁇ 1, -1, 3, -3 ⁇ ; the Xstd' and Ystd' corresponding to 64QAM are ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ .
  • Preferred embodiment 1 (transmitter)
  • FIG. 6 is a schematic diagram of a wireless broadcast communication system implemented using a superposition method of a downlink multi-user information transmission system in accordance with a preferred embodiment of the present invention.
  • the base station can transmit multi-user information to two user equipments (ie, UE1 and UE2).
  • the two bit streams can be modulated into complex symbol sequences S1 and S2 of a certain power, and a complex symbol sequence S3 is obtained after the varying superposition process.
  • the two bit information streams are obtained by Turbo coding by the dual information bit stream to be sent to the user, wherein the protection priority of C1 is greater than the protection priority of C2.
  • C1 and C2 are modulated into complex symbol sequences S1 and S2 having a certain power, wherein the modulation order of S1 is lower than or equal to the modulation order of S2.
  • the spectral effect of UE1 needs to be smaller than the spectral effect of UE2, wherein the complex symbol sequence S1 is obtained by multiplying C1 by a power normalized constellation-modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the complex symbol sequence S2 is obtained by multiplying C2 by a power normalized constellation-modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the unnormalized integer lattice constellation symbol S std corresponding to S1 is Xstd+Ystd ⁇ i.
  • the unnormalized integer lattice constellation symbol S std is Xstd+Ystd ⁇ i.
  • the Xstd and Ystd corresponding to QPSK are ⁇ 1, -1 ⁇ ;
  • the Xstd and Ystd corresponding to 16QAM are ⁇ 1, -1. , 3, -3 ⁇ ;
  • the Xstd and Ystd corresponding to 64QAM are ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ .
  • the complex symbol sequence S1 and S2 undergo the change superposition processing means that the complex symbol sequence S1 and the complex symbol sequence S2 are directly superimposed, and the directly superposed complex symbol sequence S3 can be expressed as (S1+S). It can be expressed as: Among them, the symbol Indicates rounding up.
  • the constellation of the superposed complex symbol S3 has a Gray attribute
  • the superposed symbol constellation has a Gray attribute by other methods, wherein the symbol of the real part of S can be determined according to the value of the real part of S1, which can be determined according to the value of the imaginary part of S1.
  • the symbol S after the change of the complex symbol sequence S2 can be expressed as:
  • the power of the symbol S is the same as the power of S2.
  • the base station may form the superposed processed symbols into a transmit signal, the edge user UE1 and the central user UE2 in the transmitted cell.
  • Preferred embodiment 2 (receiver)
  • the receiver may include, but is not limited to, a receiving module, a demodulation module, and a decoding module.
  • the two bit streams are transmitted on the "entire channel", and the edge user or receiver 1 demodulates the required information with other interference information, and the central user or receiver 2 demodulates the interference information and removes the interference information. , demodulate the required information.
  • the edge user first receives the complex symbol sequence R1, and then demodulates the strong signal (the information sent to the edge user) S1' with the interference of the weak signal (the information sent to the central user), and finally decodes the edge.
  • the edge user first receives the complex symbol sequence R1, and then demodulates the strong signal (the information sent to the edge user) S1' with the interference of the weak signal (the information sent to the central user), and finally decodes the edge.
  • User's information B1' User's information B1'.
  • the central user first receives R2, then demodulates the strong signal S1' in the demodulation module 1, and transmits the demodulation information to the demodulation module 2, and the demodulation module 2 removes the strong signal from R2.
  • the weak signal S2' is then demodulated, and finally the central user's information B2' is decoded.
  • the receiver demodulates the edge user's information as x1'+y1' ⁇ i, and the SIC demodulated complex symbol is x2'+y2' ⁇ i, then the changed signal S2' is: or Wherein, S std ' is S1' corresponding to the unnormalized integer lattice constellation symbol represented as Xstd'+Ystd' ⁇ i. symbol Indicates rounding up, Indicates rounding down.
  • the receivers of the two users can be designed in the same way, the central user needs to use two demodulation modules, and the edge users only need to use the demodulation module 1.
  • FIG. 8 is a schematic structural diagram of a superimposing apparatus of a downlink multi-user information transmission system according to a preferred embodiment of the present invention.
  • 9 is a schematic structural diagram of a transmitter module of a superimposing apparatus of a downlink multi-user information transmission system according to a preferred embodiment of the present invention.
  • the superimposing apparatus may include, but is not limited to, a transmitter BS, a channel, and a receiver.
  • the transmitted signal arrives at the receiver 1 via channel 1 and reaches the receiver 2 via channel 2.
  • the BS stores radio channel related information with each receiver, and there is a large difference in radio channel quality from the BS to the receiver 1 and from the BS to the receiver 2, for example, a difference of 20 dB.
  • the transmitter can be a base station, a relay node or a network Network coding node.
  • the receiver can be a mobile or fixed wireless communication device, and can also be referred to as a mobile node, and the node can move arbitrarily within the effective communication range.
  • the transmitter can complete the above superposition.
  • the transmitter may include, but is not limited to, an encoding module, a modulation module, a scheduling module, a power distribution module, a superimposing module, and a transmitting module.
  • the two bit information streams are modulated into a complex symbol sequence S1 and S2 having a certain power and superposed to obtain a complex symbol sequence S3.
  • the user information streams B1 and B2 can be subjected to Turbo coding processing to obtain two bit information streams C1 and C2, wherein the C1 protection priority is greater than the protection priority of C2.
  • C1 and C2 are modulated to obtain a complex symbol sequence having a normalized average power and multiplied by a power adjustment factor to obtain S1 and S2, wherein the modulation order of S1 is less than or equal to the modulation order of S2.
  • S1 and S2 are superimposed to obtain S3, wherein the modulation order of S3 is higher than the S1 or S2 modulation order.
  • C1 passes through the modulation module and gets S1 as After C2 passes through the modulation module, S2 is obtained.
  • the scheduling module can schedule the packet outbound edge user receiver 1 and the central user receiver 2.
  • the power distribution module can set the power adjustment factor according to the identification signal of the scheduling module C1 is modulated by the power normalized constellation and multiplied by the power adjustment factor to obtain S1 as C2 is modulated by the power normalized constellation and multiplied by the power adjustment factor to obtain S2 among them, more than the when less than or equal to At this time, there is no need to perform a constellation change on the symbol sequence S2.
  • the complex symbol sequence S1 and S2 are superimposed by change, which means that the complex symbol sequence S1 and the complex symbol sequence S2 are directly superimposed, and the directly superposed symbol sequence S3 can be expressed as (S1+S).
  • the sign of the real part of S can be determined according to the value of the real part of S1
  • the sign of the imaginary part can be determined according to the value of the imaginary part of S1.
  • the symbol S after the change of the complex symbol sequence S2 is expressed as or Among them, the symbol Indicates rounding up, Indicates rounding down.
  • the power of the symbol S is the same as the power of S2.
  • S1 and S2 are superimposed to obtain a complex symbol sequence S3.
  • the constellation of the superposed complex symbol S3 has a Gray attribute
  • the superposed symbol constellation has a Gray attribute by other methods.
  • the transmitting module may form the superposed symbols to form a transmission signal T, which is transmitted to the edge user receiver 1 and the central user receiver 2 in the cell.
  • the above system may also be a network system having a plurality of cell cells.
  • the transmitter needs to transmit the first set of information to the edge user and the second set of information to the central user.
  • the first group of information and the second group of information may be coded and modulated according to a code rate and a modulation scheme of an existing standard.
  • the two bit information streams C1 and C2 are respectively obtained by Turbo coding of the dual information bit stream to be sent to the user, wherein the C1 protection priority is greater than the protection priority of C2.
  • C1 and C2 are modulated into complex symbol sequences S1 and S2 having a certain power, wherein the modulation order of S1 is less than or equal to the modulation order of S2.
  • the modulation scheme can be varied, such as BPSK, QPSK, 16QAM or other existing modulation schemes.
  • the edge user's spectral performance needs to be less than the central user's spectral effect.
  • the complex symbol sequence S1 is obtained by multiplying C1 by a power normalized constellation-modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the complex symbol sequence S2 is obtained by multiplying C2 by a power normalized constellation-modulated power-normalized modulation symbol sequence by a power adjustment factor.
  • the power adjustment factor of S1 is C1 is modulated by the power normalized constellation and multiplied by the power adjustment factor to obtain S1 as C2 is modulated by the power normalized constellation and multiplied by the power adjustment factor to obtain S2 more than the when less than or equal to At this time, there is no need to perform a constellation change on the symbol sequence S2.
  • the power distribution module can set a power adjustment factor, such as:
  • the complex symbol sequence S1 and S2 are superimposed by change, which means that the complex symbol sequence S1 and the complex symbol sequence S2 are directly superimposed, and the directly superposed complex symbol sequence S3 can be expressed as (S1+S), or can be expressed.
  • the symbol Indicates rounding down.
  • the constellation of the superposed complex symbol S3 has a Gray attribute, and the superposed symbol constellation has a Gray attribute by other methods.
  • FIG. 10 is a schematic diagram showing a process of changing a QPSK signal of a center user according to a preferred embodiment of the present invention. As shown in FIG.
  • FIG 11 is a schematic illustration of a superimposition process that remains unchanged after a change process in accordance with a preferred embodiment of the present invention. As shown in Figure 11, the complete stacking process is as follows:
  • Step 2 The symbol S1 is directly superimposed with the changed symbol S to obtain the superimposed symbol S3.
  • Figure 12 is a schematic illustration of a superimposition process for horizontal flipping after a variation process in accordance with a preferred embodiment of the present invention. As shown in Figure 12, the complete stacking process is as follows:
  • Step 2 the symbol S1 and the changed symbol S are directly superimposed to obtain the superimposed symbol S3.
  • the superimposed symbol S3 obtained by superimposing the symbol S2 is Gray mapped, and, more importantly, even if the symbol S1 is misjudged due to noise at the receiver, The symbol S2 is demodulated and then changed again to still correctly demodulate the symbol S2, so that the performance of the near-end user is significantly improved.
  • the transmitter needs to transmit the first set of information to the edge user and the second set of information to the central user.
  • the two bit streams C1, C2 are obtained by Turbo encoding by the bi-information bit stream to be transmitted to the user, respectively.
  • C1 and C2 are modulated into complex symbol sequences S1 and S2 with a certain power, assuming that the power adjustment factor of S1 is The power adjustment factor of S2 is And more than the Then the complex symbol sequence S1 is Complex symbol sequence S2 is
  • the unnormalized integer lattice constellation symbol S std corresponding to S1 is Xstd+Ystd ⁇ i.
  • the unnormalized integer lattice constellation symbol S std is Xstd+Ystd ⁇ i.
  • the Xstd and Ystd corresponding to QPSK are ⁇ 1, -1 ⁇ ; the Xstd and Ystd corresponding to 16QAM are ⁇ 1, -1. , 3, -3 ⁇ ; the Xstd and Ystd corresponding to 64QAM are ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ .
  • the power distribution module sets the power adjustment factor, for example:
  • the complex symbol sequence S1 and S2 undergo the change superposition processing means that the complex symbol sequence S1 and the complex symbol sequence S2 are directly superimposed with the symbol S, and the directly superposed complex symbol sequence S3 can be expressed as Among them, the symbol Indicates rounding up.
  • the constellation of the superposed complex symbol S3 has a Gray attribute, and the superposed symbol constellation has a Gray attribute by other methods.
  • the above two sets of information can be modulated by 16QAM according to the standard, the sign of the real part of S is determined according to the value of the real part of S1, and the sign of the imaginary part is determined according to the value of the imaginary part of S1.
  • the symbol S after the change of the complex symbol sequence S2 is expressed as The power of the symbol S is the same as the power of the S2.
  • 13 is a schematic diagram of a process of changing a 16QAM signal of a center user in accordance with a preferred embodiment of the present invention. As shown in FIG. 13, in the case of 16 points corresponding to S1, S2 is correspondingly changed. In the horizontal direction, the S obtained by the change of S2 at the laterally adjacent points of S1 is horizontally inverted.
  • the S obtained by the change of S2 at the longitudinal adjacent points of S1 is a vertical flip relationship.
  • FIG. 14 is a structural block diagram of a superimposing apparatus for multi-user information transmission according to an embodiment of the present invention.
  • the superimposing apparatus for multi-user information transmission may include: a modulation module 10 configured to separately modulate two bit information streams into a first complex symbol sequence and a second complex symbol sequence; and the superimposing module 20 is configured to Performing a superposition process on the first complex symbol sequence and the second complex symbol sequence to generate a third complex symbol sequence, wherein the third complex symbol sequence has a Gray mapping attribute; and the sending module 30 is configured to form a transmitting signal according to the third complex symbol sequence And transmit the transmitted signal to multiple receivers.
  • the apparatus shown in FIG. 14 solves the problem that the plurality of user signals in the related art are directly added and the final combined constellation points have no Gray mapping attribute, thereby simplifying the SIC receiver in the NOMA downlink broadcast communication system.
  • the receiving end performs the symbol level SIC demodulation as much as possible, and at the same time, the superimposed symbols have the Gray attribute, and the different powers can be allocated to different data streams in a simple and flexible manner, thereby improving the multiple access performance.
  • the modulation module 10 may include: a first modulating unit 100 configured to modulate the first information stream of the two bit information streams by power normalized constellation modulation.
  • the symbol sequence is multiplied by the first power adjustment factor to obtain a first complex symbol sequence;
  • the second modulation unit 102 is configured to normalize the power of the second information stream in the two bit streams through the power normalized constellation modulation.
  • the modulation symbol sequence is multiplied by the second power adjustment factor to obtain a second complex symbol sequence; wherein the length of the first complex symbol sequence includes: 1.
  • the length of the second complex symbol sequence includes: 1.
  • the first power adjustment factor is greater than the second power adjustment factor, and the modulation order of the first complex symbol sequence is lower than or equal to the modulation order of the second complex symbol sequence.
  • the superimposing module 20 may further include: an obtaining unit 200 configured to change the amplitude of the second complex symbol sequence in the complex plane according to the first complex symbol sequence, the amplitude remains unchanged, and obtain the changed symbol. a sequence; the superposition unit 202 is configured to perform a superposition process on the first complex symbol sequence and the changed symbol sequence to generate a third complex symbol sequence.
  • the obtaining unit 200 may include: a first acquiring subunit (not shown in the figure), configured to determine a real part symbol of the changed symbol sequence according to a real part value of the first complex symbol sequence; the second obtaining sub A unit (not shown) is arranged to determine an imaginary part symbol of the changed symbol sequence based on the imaginary part of the first complex symbol sequence.
  • the encoding unit 202 is configured to perform superimposition processing on the first complex symbol sequence and the changed symbol sequence, and the generating the third complex symbol sequence may include one of the following manners:
  • Xstd+Ystd ⁇ i is an unnormalized integer lattice constellation symbol corresponding to the first complex symbol sequence, including: BPSS corresponding X std takes the value ⁇ 1, -1 ⁇ , Ystd Take the zero; QSTK corresponds to X std and Y std as ⁇ 1, -1 ⁇ ; 16QAM corresponds to X std and Y std as ⁇ 1, -1, 3, -3 ⁇ ; 64QAM corresponds to X std , Y std takes the values ⁇ 1, -1, 3, -3, 5, -5, 7, -7 ⁇ ; For the first power adjustment factor, For the second power adjustment factor, Indicates rounding up, Indicates rounding down.
  • the apparatus may further include: an adjustment module 40 configured to adjust the third complex symbol sequence by adjusting a first power adjustment factor and/or a second power adjustment factor; or, by adjusting A power adjustment factor and/or a second power adjustment factor adjusts the constellation map of the third complex symbol sequence mapping.
  • an adjustment module 40 configured to adjust the third complex symbol sequence by adjusting a first power adjustment factor and/or a second power adjustment factor; or, by adjusting A power adjustment factor and/or a second power adjustment factor adjusts the constellation map of the third complex symbol sequence mapping.
  • the apparatus may further include: a generating module 50 configured to determine, according to a channel condition, a coding and modulation manner to encode two user information streams to generate two bit information streams, where two users The protection priority of the first user information flow in the information is greater than the protection priority of the second user information flow in the two user information.
  • a generating module 50 configured to determine, according to a channel condition, a coding and modulation manner to encode two user information streams to generate two bit information streams, where two users The protection priority of the first user information flow in the information is greater than the protection priority of the second user information flow in the two user information.
  • the demodulation apparatus for multi-user information transmission may include: a receiving module 60 configured to receive a transmission signal from a transmitter, wherein the transmission signal is separately modulated into two bit streams on the transmitter. a first complex symbol sequence and a second complex symbol sequence, and the first complex symbol sequence and the second complex symbol sequence are superimposed to generate a third complex symbol sequence, and the third complex symbol sequence is formed according to the third complex symbol sequence There is a Gray mapping attribute; the demodulation module 70 is configured to demodulate the received signal according to its own type using a corresponding demodulation method.
  • the demodulation module 70 may include: a first demodulation unit 700 configured to directly demodulate the received signal from the interference signal when determining that the type is a cell edge user. The first part of the signal is sent to the cell edge user; the first decoding unit 702 is configured to decode the user information corresponding to the cell edge user from the first part of the signal.
  • the demodulation module 70 may include: a second demodulation unit 704 configured to directly demodulate the received signal from the interference signal when determining that the type of the user is a cell center user. Sending to the first part of the cell edge user signal; the third demodulating unit 706 is configured to remove the first part of the received signal and demodulate the second part of the user to be transmitted to the cell center from the remaining part of the signal a signal processing unit 708 is configured to change the amplitude of the second partial signal in the complex plane according to the first partial signal, the amplitude remains unchanged, and obtain the changed second partial signal; and the second decoding unit 710 is configured to be changed from The user information corresponding to the cell center user is decoded in the second part of the signal.
  • a second demodulation unit 704 configured to directly demodulate the received signal from the interference signal when determining that the type of the user is a cell center user. Sending to the first part of the cell edge user signal
  • the third demodulating unit 706 is configured to remove the first part
  • the time-frequency resources of the channels used by each user to receive the transmitted signals are the same and overlapped.
  • modules or steps of the present invention described above can be implemented by a general-purpose computing device that can be centralized on a single computing device or distributed across multiple computing devices.
  • they may be implemented by program code executable by the computing device such that they may be stored in the storage device by the computing device and, in some cases, may be different from this
  • the steps shown or described are performed sequentially, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps thereof are fabricated into a single integrated circuit module.
  • the invention is not limited to any specific combination of hardware and software.
  • the method and apparatus for superimposing and demodulating multi-user information transmission provided by the embodiments of the present invention have the following beneficial effects:
  • the SIC receiver is simplified in the NOMA downlink broadcast communication system, so that the receiving end performs symbols as much as possible.
  • the SIC demodulation of the stage makes the superimposed symbols have the Gray attribute, and can allocate different powers for different data streams simply and flexibly, and improve the multiple access performance.

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Abstract

本发明公开了一种多用户信息传输的叠加、解调方法及装置，在上述方法中，将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，第三复数符号序列具有Gray映射属性；根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机。根据本发明提供的技术方案，不仅能够使得接收端进行符号级的SIC解调，极大地简化SIC接收机，而且还能够使得叠加编码后的符号又具有Gray属性，此外还可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入的性能。

Description

多用户信息传输的叠加、解调方法及装置 技术领域
本发明涉及通信领域，具体而言，涉及一种多用户信息传输的叠加、解调方法及装置。
背景技术
多用户信息传输技术或者称为多址复用技术，其可以分为正交多址接入(Orthogonal Multiple Access，简称为OMA)和非正交多址接入(None Orthogonal Multiple Access，简称为NOMA)。传统的TDMA、正交CDMA、OFDMA均属于正交多址复用技术的范畴。在正交多址复用技术中，各个用户使用严格相互正交的“子通道”来进行通信，因而在解调时各用户信息之间没有相互干扰，进而分离用户信息较容易。相对地，在非正交多址复用技术中，每个用户的信息都是在“整个通道”上传输的，在解调时各用户信息之间是相互干扰的，所以分离用户信息较为麻烦。
非正交多址复用技术通常可以分为两种解调方法：
第一种、每个用户都带着其他用户的干扰解调，这样实现较为简单，但性能是有损的。
第二种、是使用干扰消除技术，也即多用户检测技术。
下面以两个用户的串行干扰消除(Successive Interference Cancellation，简称为SIC)过程为例进行简单说明，多用户的SIC过程很容易由此推广：先解调译码出用户A的信息(带着用户B的干扰来解调译码A信息)。然后，在解调用户B信息时，需要先将之前解调译码出来的A信息(可能需要重构)减去，再解调出用户B信息。这样用户B信息因为可以没有干扰，所以性能可以存在较大提升。相关技术中采用非正交多址复用结合SIC技术是可以达到多用户信息容量极限的。
接下来将要描述的是在无线通信系统中的下行多用户信息传输系统中的叠加编码技术。图1是根据相关技术的NOMA下行广播示意图。如图1所示，下行多用户信息传输通常也被称为下行广播，其指的是发射机可以采用非正交的方式向多个接收机发送各自所需信息。此处需要注意的是，这里多用户多址“广播”是指不同用户的信息 通过基站一起发出去，与传统中广播(例如：电台广播)中基站向所有用户发送相同信息是有所区别的。
图2是根据相关技术的NOMA方式和OMA方式的容量对比示意图。如图2所示，下行多用户信息传输技术(下行广播)有非正交多址接入(NOMA)和正交多址接入(OMA)两种接入方式。NOMA方式因为每个用户可以使用全部自由度，能够取得比OMA方式更大的系统容量或边缘吞吐量。特别地，NOMA下行广播能够更加优先地提高边缘用户的容量，同时基本保持中心用户的高吞吐量。在NOMA广播发送之前，要将多个用户的信号叠加到一起，然后在相同的时频资源上进行发送。将多个用户信号进行叠加的过程又称为“叠加编码”。
多个用户信号直接相加起来即为一种最简单的“叠加编码”，而且这种最简单的直接相加的叠加编码方式结合码块级SIC也可以达到下行多用户信道容量界限。不过，这种最简单的直接相加的叠加编码方式由于最终组合出的星座点没有Gray映射(映射的相邻星座点仅存在1个比特不同，这样调制的性能最优)的属性。图3是根据相关技术的多个用户信号直接叠加编码的示意图。如图3所示，即为QPSK符号和QPSK符号直接叠加的星座。终端如果使用简单的符号级SIC接收，其解调性能会下降较大，因而，为了保证性能，终端需要使用复杂的码块级SIC。码块级SIC对终端而言会引起很高的实现复杂度、功耗和时延，这些对终端来说有时是不可接受的。
分层调制(Hierarchical modulation)也可以看做一种叠加编码的变种。分层调制是指通过高优先比特流和低优先比特流的组合而形成叠加后的调制符号。虽然分层调制也可以组合出具有Gray映射属性的星座，但分层调制对不同数据流的进行不同功率分配很不灵活，而且其实现复杂度也较高。而对不同数据流进行不同功率分配是达到下行多用户信道容量的必要手段。
综上所述，相关技术中的多个用户信号直接相加最终组合出的星座点缺少Gray映射属性。
发明内容
本发明实施例提供了一种多用户信息传输的叠加、解调方法及装置，以至少解决相关技术中的多个用户信号直接相加最终组合出的星座点没有Gray映射属性的问题。
根据本发明实施例的一个方面，提供了一种多用户信息传输的叠加方法。
根据本发明实施例的多用户信息传输的叠加方法包括：将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，第三复数符号序列具有Gray映射属性；根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机。
优选地，将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列包括：将两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第一功率调整因子得到第一复数符号序列；将两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第二功率调整因子得到第二复数符号序列；其中，第一复数符号序列的长度包括：1，第二复数符号序列的长度包括：1，第一功率调整因子大于第二功率调整因子，第一复数符号序列的调制阶数低于或等于第二复数符号序列的调制阶数。
优选地，采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列包括：根据第一复数符号序列改变第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列。
优选地，改变第二复数符号序列，获取变化后的符号序列包括：根据第一复数符号序列的实部取值确定变化后的符号序列的实部符号；根据第一复数符号序列的虚部取值确定变化后的符号序列的虚部符号。
优选地，将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列包括以下之一：第三复数符号序列为
Figure PCTCN2015083474-appb-000001
Figure PCTCN2015083474-appb-000002
第三复数符号序列为
Figure PCTCN2015083474-appb-000003
Figure PCTCN2015083474-appb-000004
其中，
Figure PCTCN2015083474-appb-000005
为第一复数符号序列，
Figure PCTCN2015083474-appb-000006
为第二复数符号序列，
Figure PCTCN2015083474-appb-000007
或者
Figure PCTCN2015083474-appb-000008
Figure PCTCN2015083474-appb-000009
为变化后的符号序列，Xstd+Ystd·i为与第一复数符号序列对应的未归一化的整数格点星座符号，包括：BPSK对应的Xstd取值为{1，-1}，Ystd取零；QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}；
Figure PCTCN2015083474-appb-000010
为第一功率调整因子，
Figure PCTCN2015083474-appb-000011
为第二功率调整因子，
Figure PCTCN2015083474-appb-000012
表示向上取整，
Figure PCTCN2015083474-appb-000013
表示向下取整。
优选地，在生成第三复数符号序列之后，还包括：通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列进行调整；或者，通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列映射的星座图进行调整。
优选地，在将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列之前，还包括：根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成两个比特信息流，其中，两个用户信息中的第一用户信息流的保护优先级大于两个用户信息中的第二用户信息流的保护优先级。
根据本发明实施例的另一方面，提供了一种多用户信息传输的解调方法。
根据本发明实施例的多用户信息传输的解调方法包括：接收来自于发射机的发射信号，其中，发射信号是在发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用第一复数符号序列与第二复数符号序列进行叠加处理生成第三复数符号序列之后，根据第三复数符号序列形成的，第三复数符号序列具有Gray映射属性；根据自身类型采用对应的解调方式对接收信号进行解调。
优选地，根据自身类型采用对应的解调方式对接收信号进行解调包括：在确定自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；从第一部分信号中解码出与小区边缘用户对应的用户信息。
优选地，根据自身类型采用对应的解调方式对接收信号进行解调包括：在确定自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；对接收信号中的第一部分信号进行去除，并从剩余的部分信号中解调出待发送至小区中心用户的第二部分信号；根据第一部分信号改变第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；从变化后的第二部分信号中解码出与小区中心用户对应的用户信息。
优选地，各个用户接收发射信号所使用的信道的时频资源相同且重叠使用。
根据本发明实施例的又一方面，提供了一种多用户信息传输的叠加装置。
根据本发明实施例的多用户信息传输的叠加装置包括：调制模块，设置为将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；叠加模块，设置为采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其 中，第三复数符号序列具有Gray映射属性；发送模块，设置为根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机。
优选地，调制模块包括：第一调制单元，设置为将两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第一功率调整因子得到第一复数符号序列；第二调制单元，设置为将两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第二功率调整因子得到第二复数符号序列；其中，第一复数符号序列的长度包括：1，第二复数符号序列的长度包括：1，第一功率调整因子大于第二功率调整因子，第一复数符号序列的调制阶数低于或等于第二复数符号序列的调制阶数。
优选地，叠加模块包括：获取单元，设置为根据第一复数符号序列改变第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；叠加单元，设置为将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列。
优选地，获取单元包括：第一获取子单元，设置为根据第一复数符号序列的实部取值确定变化后的符号序列的实部符号；第二获取子单元，设置为根据第一复数符号序列的虚部取值确定变化后的符号序列的虚部符号。
优选地，编码单元，设置为将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列包括以下之一：第三复数符号序列为
Figure PCTCN2015083474-appb-000014
Figure PCTCN2015083474-appb-000015
第三复数符号序列为
Figure PCTCN2015083474-appb-000016
Figure PCTCN2015083474-appb-000017
其中，
Figure PCTCN2015083474-appb-000018
为第一复数符号序列，
Figure PCTCN2015083474-appb-000019
为第二复数符号序列，
Figure PCTCN2015083474-appb-000020
或者
Figure PCTCN2015083474-appb-000021
为变化后的符号序列，Xstd+Ystd·i为与第一复数符号序列对应的未归一化的整数格点星座符号，包括：BPSK对应的Xstd取值为{1，-1}，Ystd取零；QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}；
Figure PCTCN2015083474-appb-000022
为第一功率调整因子，
Figure PCTCN2015083474-appb-000023
为第二功率调整因子，
Figure PCTCN2015083474-appb-000024
表示向上取整，
Figure PCTCN2015083474-appb-000025
表示向下取整。
优选地，上述装置还包括：调整模块，设置为通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列进行调整；或者，通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列映射的星座图进行调整。
优选地，上述装置还包括：生成模块，设置为根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成两个比特信息流，其中，两个用户信息中的第一用户信息流的保护优先级大于两个用户信息中的第二用户信息流的保护优先级。
根据本发明实施例的再一方面，提供了一种多用户信息传输的解调装置。
根据本发明实施例的多用户信息传输的解调装置包括：接收模块，设置为接收来自于发射机的发射信号，其中，发射信号是在发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用第一复数符号序列与第二复数符号序列进行叠加处理生成第三复数符号序列之后，根据第三复数符号序列形成的，第三复数符号序列具有Gray映射属性；解调模块，设置为根据自身类型采用对应的解调方式对接收信号进行解调。
优选地，解调模块包括：第一解调单元，设置为在确定自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；第一解码单元，设置为从第一部分信号中解码出与小区边缘用户对应的用户信息。
优选地，解调模块包括：第二解调单元，设置为在确定自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；第三解调单元，设置为对接收信号中的第一部分信号进行去除，并从剩余的部分信号中解调出待发送至小区中心用户的第二部分信号；处理单元，设置为根据第一部分信号改变第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；第二解码单元，设置为从变化后的第二部分信号中解码出与小区中心用户对应的用户信息。
优选地，各个用户接收发射信号所使用的信道的时频资源相同且重叠使用。
通过本发明实施例，采用将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，第三复数符号序列具有Gray映射属性；根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机，解决了相关技术中的多个用户信号直接相加最终组合出的星座点没有Gray映射属性的的问题，进而在NOMA下行广播通信系统中简化了SIC接收机，使得接收端尽可能地进行符号级的SIC解调，同时使叠加后的符号又具有Gray属性，且可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入性能。
附图说明
此处所说明的附图用来提供对本发明的进一步理解，构成本申请的一部分，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。在附图中：
图1是根据相关技术的NOMA下行广播示意图；
图2是根据相关技术的NOMA方式和OMA方式的容量对比示意图；
图3是根据相关技术的多个用户信号直接叠加的示意图；
图4是根据本发明实施例的多用户信息传输的叠加方法的流程图；
图5是根据本发明实施例的多用户信息传输的解调方法的流程图；
图6是根据本发明优选实施例的采用下行多用户信息传输系统的叠加方法实施的无线广播通信系统示意图；
图7是根据本发明优选实施例的下行多用户信息传输系统的典型接收机结构示意图；
图8根据本发明优选实施例的下行多用户信息传输系统的叠加装置的结构示意图；
图9是根据本发明优选实施例的下行多用户信息传输系统的叠加装置的发射机模块的结构示意图；
图10是根据本发明优选实施例的中心用户的QPSK信号进行改变处理过程的示意图；
图11是根据本发明优选实施例的在改变处理后保持不变的叠加过程示意图；
图12是根据本发明优选实施例的在改变处理后进行水平映射的叠加过程示意图；
图13是根据本发明优选实施例的中心用户的16QAM信号进行改变过程的示意图；
图14是根据本发明实施例的多用户信息传输的叠加装置的结构框图；
图15是根据本发明优选实施例的多用户信息传输的叠加装置的结构框图；
图16是根据本发明实施例的多用户信息传输的解调装置的结构框图；
图17是根据本发明优选实施例的多用户信息传输的解调装置的结构框图。
具体实施方式
下文中将参考附图并结合实施例来详细说明本发明。需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
图4是根据本发明实施例的多用户信息传输的叠加方法的流程图。如图4所示，该方法可以包括以下处理步骤：
步骤S402：将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；
步骤S404：采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，第三复数符号序列具有Gray映射属性；
步骤S406：根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机。
相关技术中的多个用户信号直接相加最终组合出的星座点没有Gray映射属性。采用如图4所示的方法，发射机可以将中心用户的星座进行相应的改变处理后再进行叠加处理，然后将叠加后的符号形成发射信号，发送至小区内边缘用户接收机和中心用户接收机。因而，针对NOMA下行广播系统，不仅能够使得接收端进行符号级的SIC解调，极大地简化SIC接收机，而且还能够使得叠加后的符号又具有Gray属性，此外还可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入的性能，特别是提高了小区中心用户的性能。
需要说明的是，本发明实施例所提供的下行多用户信息传输系统的叠加方案可以支持旧版本的下行广播系统。
优选地，在步骤S402中，将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列可以包括以下操作：
步骤S1：将两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第一功率调整因子得到第一复数符号序列；
步骤S2：将两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第二功率调整因子得到第二复数符号序列；
其中，第一复数符号序列的长度包括：1，第二复数符号序列的长度包括：1，第一功率调整因子大于第二功率调整因子，第一复数符号序列的调制阶数低于或等于第二复数符号序列的调制阶数。
在优选实施例中，复数符号序列S1是指将C1经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。复数符号序列S2是指将C2经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。C1调制后具有一定功率的复数符号序列S1为
Figure PCTCN2015083474-appb-000026
C2调制后具有一定功率的复数符号序列S2为
Figure PCTCN2015083474-appb-000027
S1的功率调整因子为
Figure PCTCN2015083474-appb-000028
S2的功率调整因子为
Figure PCTCN2015083474-appb-000029
大于
Figure PCTCN2015083474-appb-000030
当
Figure PCTCN2015083474-appb-000031
小于或等于
Figure PCTCN2015083474-appb-000032
时，无需对符号序列S2进行星座改变。
优选地，在步骤S404中，采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列可以包括以下步骤：
步骤S3：根据第一复数符号序列改变第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；
步骤S4：将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列。
在优选实施例中，复数符号序列S1和S2经过叠加可以是复数符号序列S1和复数符号序列S2改变后的符号S直接叠加，直接叠加后的复数符号序列S3可表示为(S1+S)。S1和S2改变后的符号直接叠加得到S3。S3的星座点具有Gray属性，可以通过其它的方法使叠加后符号星座具有Gray属性。
优选地，在步骤S3中，改变第二复数符号序列，获取变化后的符号序列可以包括操作：
步骤S31：根据第一复数符号序列的实部取值确定变化后的符号序列的实部符号；
步骤S32：根据第一复数符号序列的虚部取值确定变化后的符号序列的虚部符号。
在优选实施例中，在复数符号序列S2与S1进行叠加处理之前需要经过变化处理，根据S1实部的值确定S实部的符号，根据S1虚部的值确定S虚部的符号。复数符号 序列S2变化后的符号S可以表示为：
Figure PCTCN2015083474-appb-000033
或者
Figure PCTCN2015083474-appb-000034
符号S的功率和S2的功率一样。
优选地，在步骤S4中，将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列可以包括以下方式之一：
方式一、第三复数符号序列为
Figure PCTCN2015083474-appb-000035
Figure PCTCN2015083474-appb-000036
方式二、第三复数符号序列为
Figure PCTCN2015083474-appb-000037
Figure PCTCN2015083474-appb-000038
其中，
Figure PCTCN2015083474-appb-000039
为第一复数符号序列，
Figure PCTCN2015083474-appb-000040
为第二复数符号序列，
Figure PCTCN2015083474-appb-000041
或者
Figure PCTCN2015083474-appb-000042
Figure PCTCN2015083474-appb-000043
为变化后的符号序列，Xstd+Ystd·i为与第一复数符号序列对应的未归一化的整数格点星座符号，包括：BPSK对应的Xstd取值为{1，-1}，Ystd取零；QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}；
Figure PCTCN2015083474-appb-000044
为第一功率调整因子，
Figure PCTCN2015083474-appb-000045
为第二功率调整因子，
Figure PCTCN2015083474-appb-000046
表示向上取整，
Figure PCTCN2015083474-appb-000047
表示向下取整。
在优选实施例中，假设C1调制后具有一定功率的复数符号序列S1为
Figure PCTCN2015083474-appb-000048
Figure PCTCN2015083474-appb-000049
C2调制后具有一定功率的复数符号序列S2为
Figure PCTCN2015083474-appb-000050
S1对应的未归一化的整数格点星座符号Sstd为Xstd+Ystd·i，则S1和S2经过变化叠加后得到复数符号序列S3可以为
Figure PCTCN2015083474-appb-000051
Figure PCTCN2015083474-appb-000052
是功率调整因子，符号
Figure PCTCN2015083474-appb-000053
表示向上取整。
上述未归一化整数格点星座符号Sstd为Xstd+Ystd·i，例如：QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}。
另外，还可以假设C1调制后具有一定功率的复数符号序列S1为
Figure PCTCN2015083474-appb-000054
C2调制后具有一定功率的复数符号序列S2为
Figure PCTCN2015083474-appb-000055
S1对应的未归一化的整数格点星座符号Sstd为Xstd+Ystd·i，则S1和S2经过改变叠加后得到复数符号序列S3可以为
Figure PCTCN2015083474-appb-000056
Figure PCTCN2015083474-appb-000057
Figure PCTCN2015083474-appb-000058
是功率调整因子，符号
Figure PCTCN2015083474-appb-000059
表示向下取整。
上述未归一化整数格点星座符号Sstd为Xstd+Ystd·i，例如：QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}。
优选地，在步骤S404，生成第三复数符号序列，还可以包括以下操作：
步骤S5：通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列进行调整；或者，通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列映射的星座图进行调整。
在优选实施例中，可以根据功率调整因子
Figure PCTCN2015083474-appb-000060
调整S3，其中，
Figure PCTCN2015083474-appb-000061
大于
Figure PCTCN2015083474-appb-000062
优选地，在步骤S402，将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列之前，还可以包括以下步骤：
步骤S6：根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成两个比特信息流，其中，两个用户信息中的第一用户信息流的保护优先级大于两个用户信息中的第二用户信息流的保护优先级。
在优选实施例中，两个比特信息流可以由双信息比特流编码得到，其中，C1保护优先级大于C2的保护优先级。C1和C2被调制为具有一定功率的复数符号序列S1和S2，S1的调制阶数低于或等于S2的调制阶数。S1和S2叠加得到高于S1或S2调制阶数的调制符号。
图5是根据本发明实施例的多用户信息传输的解调方法的流程图。如图5所示，该方法可以包括以下处理步骤：
步骤S502：接收来自于发射机的发射信号，其中，发射信号是在发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用第一复数符号序列与第二复数符号序列进行叠加处理生成第三复数符号序列之后，根据第三复数符号序列形成的，第三复数符号序列具有Gray映射属性；
步骤S504：根据自身类型采用对应的解调方式对接收信号进行解调。
采用如图5所示的方法，解决了相关技术中的多个用户信号直接相加最终组合出的星座点没有Gray映射属性的的问题，进而在NOMA下行广播通信系统中简化了SIC接收机，使得接收端尽可能地进行符号级的SIC解调，同时使叠加后的符号又具有Gray属性，且可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入性能。
优选地，在步骤S504中，根据自身类型采用对应的解调方式对接收信号进行解调可以包括以下操作：
步骤S7：在确定自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；
步骤S8：从第一部分信号中解码出与小区边缘用户对应的用户信息。
即小区里边缘用户接收机1带着中心用户的干扰解调出边缘用户信息。
优选地，在步骤S504中，根据自身类型采用对应的解调方式对接收信号进行解调可以包括以下步骤：
步骤S9：在确定自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；
步骤S10：对接收信号中的第一部分信号进行去除，并从剩余的部分信号中解调出待发送至小区中心用户的第二部分信号；
步骤S11：根据第一部分信号改变第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；
步骤S12：从变化后的第二部分信号中解码出与小区中心用户对应的用户信息。
即小区里中心用户接收机2在解调出边缘用户信息并除去后，改变解码出中心用户信息。
优选地，各个用户接收发射信号所使用的信道的时频资源相同且重叠使用。每个用户的信息都是在“整个通道”上传输，整个通道指多个信道的时频资源完全相同，而且可以完全重叠使用。
在优选实施例中，假设接收端解调出边缘用户的信息S1’为x1’+y1’·i，小区内中心用户接收机2解调出边缘用户信息并除去后的信号为x2’+y2’·i，S1’对应标准未归一化整数格点星座符号Sstd’为Xstd’+Ystd’·i则进行变化处理解调出中心用户信号可以为
Figure PCTCN2015083474-appb-000063
或者
Figure PCTCN2015083474-appb-000064
其中，符号
Figure PCTCN2015083474-appb-000065
表示向上取整，
Figure PCTCN2015083474-appb-000066
表示向下取整。
上述未归一化整数格点星座符号Sstd’为Xstd’+Ystd’·i，例如：QPSK对应的Xstd’、Ystd’取值为{1，-1}；如16QAM对应的Xstd’、Ystd’取值为{1，-1，3，-3}；64QAM对应的Xstd’、Ystd’取值为{1，-1，3，-3，5，-5，7，-7}。
下面将结合优选实施例一至优选实施例五对上述优选实施过程做进一步的描述。
优选实施例一(发射机)
图6是根据本发明优选实施例的采用下行多用户信息传输系统的叠加方法实施的无线广播通信系统示意图。如图6所示，基站可以将多用户信息传输到两个用户设备(即UE1和UE2)。
在基站内，两个比特信息流可以被调制为具有一定功率的复数符号序列S1和S2，在经过变化叠加处理后得到复数符号序列S3。
首先，两个比特信息流由待发送至用户的双信息比特流分别经过Turbo编码得到，其中，C1的保护优先级大于C2的保护优先级。C1和C2被调制为具有一定功率的复数符号序列S1和S2，其中，S1的调制阶数低于或等于S2的调制阶数。UE1的谱效需要小于UE2的谱效，其中，复数符号序列S1是指将C1经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。复数符号序列S2是指将C2经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。假设S1的功率调整因子为
Figure PCTCN2015083474-appb-000067
S2的功率调整因子为
Figure PCTCN2015083474-appb-000068
且
Figure PCTCN2015083474-appb-000069
大于
Figure PCTCN2015083474-appb-000070
则复数符号序列S1为
Figure PCTCN2015083474-appb-000071
复数符号序列S2为
Figure PCTCN2015083474-appb-000072
S1对应的未归一化整数格点星座符号Sstd为Xstd+Ystd·i。未归一化整数格点星座符号Sstd为Xstd+Ystd·i，例如：QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}。
然后，复数符号序列S1和S2经过变化叠加处理是指复数符号序列S1和复数符号序列S2变化后的符号S直接叠加，直接叠加后的复数符号序列S3既可以表示为(S1+S)，也可以表示为：
Figure PCTCN2015083474-appb-000073
其中，符号
Figure PCTCN2015083474-appb-000074
表示向上取整。
根据功率调整因子
Figure PCTCN2015083474-appb-000075
调整S3，其中，
Figure PCTCN2015083474-appb-000076
大于
Figure PCTCN2015083474-appb-000077
叠加后的复数符号S3的星座具有Gray属性，可以通过其它的方法使叠加后符号星座具有Gray属性，其中，可以根据S1实部的值确定S实部的符号，可以根据S1 虚部的值确定S虚部的符号。复数符号序列S2变化后的符号S可以表示为：
Figure PCTCN2015083474-appb-000078
Figure PCTCN2015083474-appb-000079
符号S的功率与S2的功率一样。
最后，基站可以将叠加处理后的符号形成发射信号，发送之小区内的边缘用户UE1和中心用户UE2。
优选实施例二(接收机)
图7是根据本发明优选实施例的下行多用户信息传输系统的典型接收机结构示意图。如图7所示，接收机可以包括但不限于：接收模块、解调模块和解码模块。
两个比特信息流在“整个通道”上传输，边缘用户或接收机1带着其他干扰信息解调出其所需信息，中心用户或接收机2在解调出干扰信息并除去该干扰信息后，解调出所需信息。
在接收机1，边缘用户首先接收到复数符号序列R1，然后带着弱信号(发给中心用户的信息)的干扰解调出强信号(发给边缘用户的信息)S1’，最后解码出边缘用户的信息B1’。
在接收机2，中心用户首先接收到R2，然后在解调模块1中解调出强信号S1’，再将解调信息传送到解调模块2，解调模块2从R2中去除强信号，然后解调出弱信号S2’，最后解码出中心用户的信息B2’。假设接收端解调出边缘用户的信息为x1’+y1’·i，SIC解调后的复数符号为x2’+y2’·i，则变化得到的信号S2’为：
Figure PCTCN2015083474-appb-000080
Figure PCTCN2015083474-appb-000081
或者
Figure PCTCN2015083474-appb-000082
其中，Sstd’为S1’对应未归一化的整数格点星座符号表示为Xstd’+Ystd’·i。符号
Figure PCTCN2015083474-appb-000083
表示向上取整，
Figure PCTCN2015083474-appb-000084
表示向下取整。两个用户的接收机可以采用一样的设计，中心用户需要使用两个解调模块，而边缘用户只需要使用解调模块1即可。
优选实施例三(发射机模块)
图8根据本发明优选实施例的下行多用户信息传输系统的叠加装置的结构示意图。图9是根据本发明优选实施例的下行多用户信息传输系统的叠加装置的发射机模块的结构示意图。如图8和图9所示，叠加装置可以包括但不限于：发射机BS、信道以及接收机。发射信号经过信道1到达接收机1以及经过信道2到达接收机2。BS存储与各个接收机之间的无线信道相关信息，从BS到接收机1与从BS到接收机2的无线信道质量存在较大差异，例如：20dB的差异。发射机可以为基站、中继节点或者网 络编码节点。接收机可以是移动或固定的无线通信设备，也可以被称为移动节点，节点可以在有效通信范围内任意移动。
发射机可以完成上述叠加。发射机可以包括但不限于：编码模块、调制模块、调度模块、功率分配模块、叠加模块以及发射模块。两个比特信息流被调制为具有一定功率的复数符号序列S1和S2经过变化叠加后得到复数符号序列S3。
在编码模块中，用户信息流B1、B2可以经过Turbo编码处理，得到两个比特信息流C1、C2，其中，C1保护优先级大于C2的保护优先级。
在调制模块中，C1和C2经过调制得到具有归一化平均功率的复数符号序列后乘以功率调整因子得到S1和S2，其中，S1的调制阶数小于或等于S2的调制阶数。S1和S2经过叠加处理得到S3，其中，S3的调制阶数高于S1或S2调制阶数。假设C1经过调制模块后得到S1为
Figure PCTCN2015083474-appb-000085
C2经过调制模块后得到S2为
Figure PCTCN2015083474-appb-000086
Figure PCTCN2015083474-appb-000087
调度模块可以调度分组出边缘用户接收机1和中心用户接收机2。
功率分配模块可以根据调度模块的标识信号设置功率调整因子
Figure PCTCN2015083474-appb-000088
C1经过功率归一化星座图调制后乘以功率调整因子得到S1为
Figure PCTCN2015083474-appb-000089
C2经过功率归一化星座图调制后乘以功率调整因子得到S2为
Figure PCTCN2015083474-appb-000090
其中，
Figure PCTCN2015083474-appb-000091
大于
Figure PCTCN2015083474-appb-000092
当
Figure PCTCN2015083474-appb-000093
小于或等于
Figure PCTCN2015083474-appb-000094
时，无需对符号序列S2进行星座变化。
在叠加模块中，复数符号序列S1和S2经过变化叠加是指复数符号序列S1和复数符号序列S2变化后的符号S直接叠加，直接叠加后的复数符号序列S3可表示为(S1+S)，其中，可以根据S1实部的值确定S实部的符号，可以根据S1虚部的值确定S虚部的符号。复数符号序列S2变化后的符号S表示为
Figure PCTCN2015083474-appb-000095
或者
Figure PCTCN2015083474-appb-000096
其中，符号
Figure PCTCN2015083474-appb-000097
表示向上取整，
Figure PCTCN2015083474-appb-000098
表示向下取整。符号S的功率与S2的功率一样。S1和S2经过叠加后得到复数符号序列S3。叠加后的复数符号S3的星座具有Gray属性，可以通过其它的方法使得叠加后符号星座具有Gray属性。
发射模块可以将叠加后的符号形成发射信号T，发送至小区内的边缘用户接收机1和中心用户接收机2。
需要说明的是，在该优选实施例中仅提供了在一个cell下的应用情景，但其并不构成对本发明的不当限制。上述系统也可以是具有多个cell蜂窝状的网络系统。
优选实施例四
发射机需要将第一组信息传输至边缘用户，以及将第二组信息传输至中心用户。
首先，可以将上述第一组信息以及第二组信息按照现有标准的码率和调制方式进行编码调制。例如：两个比特信息流C1、C2由待发送至用户的双信息比特流分别经过Turbo编码得到，其中，C1保护优先级大于C2的保护优先级。C1和C2被调制为具有一定功率的复数符号序列S1和S2，其中，S1的调制阶数小于或等于S2的调制阶数。调制方式可以是多样的，例如：BPSK、QPSK、16QAM或其它现有调制方式。边缘用户的谱效需要小于中心用户的谱效。
复数符号序列S1是指将C1经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。复数符号序列S2是指将C2经过功率归一化星座图调制后的功率归一的调制符号序列乘以一个功率调整因子所得。假设S1的功率调整因子为
Figure PCTCN2015083474-appb-000099
C1经过功率归一化星座图调制后乘以功率调整因子得到S1为
Figure PCTCN2015083474-appb-000100
C2经过功率归一化星座图调制后乘以功率调整因子得到S2为
Figure PCTCN2015083474-appb-000101
Figure PCTCN2015083474-appb-000102
大于
Figure PCTCN2015083474-appb-000103
当
Figure PCTCN2015083474-appb-000104
小于或等于
Figure PCTCN2015083474-appb-000105
时，无需对符号序列S2进行星座变化。
功率分配模块可以设置功率调整因子，例如：
Figure PCTCN2015083474-appb-000106
然后，复数符号序列S1和S2经过变化叠加是指复数符号序列S1和复数符号序列S2变化后的符号S直接叠加，直接叠加后的复数符号序列S3可表示为(S1+S)，也可以表示为
Figure PCTCN2015083474-appb-000107
其中，符号
Figure PCTCN2015083474-appb-000108
表示向下取整。叠加后的复数符号S3的星座具有Gray属性，可以通过其它的方法使得叠加后符号星座具有Gray属性。
在该优选实施例中，假设两组信息按照标准均采用QPSK调制，根据S1实部的值确定S实部的符号，根据S1虚部的值确定S虚部的符号。复数符号序列S2变化后的符号S表示为
Figure PCTCN2015083474-appb-000109
符号S的功率与S2的功率一样。图10是根据本发明优选实施例的中心用户的QPSK信号进行变化处理过程的示意图。如图10所示，当符号Sstd为1+i，即Xstd＝1，Ystd＝1时，S为
Figure PCTCN2015083474-appb-000110
与S2一样；当符号Sstd为-1+i，即Xstd＝-1，Ystd＝1时，S为
Figure PCTCN2015083474-appb-000111
其相当于对S2进行水平变化处理；当符号Sstd为1-i，即Xstd＝1，Ystd＝-1时，S为
Figure PCTCN2015083474-appb-000112
Figure PCTCN2015083474-appb-000113
其相当于对S2进行垂直变化；当符号Sstd为-1-i，即Xstd＝-1，Ystd＝-1时，S 为
Figure PCTCN2015083474-appb-000114
其相当于对S2进行180°变化(既水平翻转又垂直翻转)。在完成变化步骤后，下个步骤则需要进行叠加处理。
图11是根据本发明优选实施例的在改变处理后保持不变的叠加过程示意图。如图11所示，其完整的叠加流程如下：
步骤1、符号S2进行变化，由S1可知，Sstd为1+i，即Xstd＝1，Ystd＝1时，S为4·(x2+y2·i)，与S2一样，即S2保持不变；
步骤2、符号S1直接与变化后的符号S叠加，得到叠加后的符号S3。
图12是根据本发明优选实施例的在变化处理后进行水平翻转的叠加过程示意图。如图12所示，其完整的叠加流程如下：
步骤1、符号S2做变化，由S1可知，Sstd为-1+i，即Xstd＝-1，Ystd＝1时，S为
Figure PCTCN2015083474-appb-000115
与S2一样，相当于S2做水平翻转；
步骤2、符号S1与变化后的符号S直接叠加，得到叠加后的符号S3。
需要说明的是，对比图3直接叠加的情况，符号S2变化后再叠加得到的叠加符号S3是Gray映射的，并且，更为重要的是，即使在接收机因为噪声误判了符号S1，对符号S2解调后再进行一次变化仍然能够正确解调出符号S2，因而近端用户的性能有明显改善。
优选实施例五
发射机需要将第一组信息传输给边缘用户，以及将第二组信息传输给中心用户。
首先，两个比特信息流C1、C2由待发送至用户的双信息比特流分别经过Turbo编码得到。C1和C2被调制为具有一定功率的复数符号序列S1和S2，假设S1的功率调整因子为
Figure PCTCN2015083474-appb-000116
S2的功率调整因子为
Figure PCTCN2015083474-appb-000117
且
Figure PCTCN2015083474-appb-000118
大于
Figure PCTCN2015083474-appb-000119
则复数符号序列S1为
Figure PCTCN2015083474-appb-000120
复数符号序列S2为
Figure PCTCN2015083474-appb-000121
S1对应的未归一化整数格点星座符号Sstd为Xstd+Ystd·i。未归一化整数格点星座符号Sstd为Xstd+Ystd·i，例如：QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}。
功率分配模块设置功率调整因子，例如：
Figure PCTCN2015083474-appb-000122
然后，复数符号序列S1和S2经过变化叠加处理是指复数符号序列S1与复数符号序列S2变化后的符号S直接叠加，直接叠加后的复数符号序列S3可以表示为
Figure PCTCN2015083474-appb-000123
其中，符号
Figure PCTCN2015083474-appb-000124
表示向上取整。叠加后的复数符号S3的星座具有Gray属性，可以通过其它的方法使得叠加后符号星座具有Gray属性。
上述两组信息按标准均可以采用16QAM调制，根据S1实部的值确定S实部的符号，根据S1虚部的值确定S虚部的符号。复数符号序列S2变化后的符号S表示为
Figure PCTCN2015083474-appb-000125
符号S的功率和S2的功率一样。图13是根据本发明优选实施例的中心用户的16QAM信号进行改变过程的示意图。如图13所示，对应S1的16个点的情况，S2做相应的变化，横向来看，在S1横向相邻点上分别对S2做的变化后得到的S互为水平翻转关系。纵向来看，在S1纵向相邻点上分别对S2做的变化后得到的S互为垂直翻转关系。例如，当符号Sstd为3+3i，即Xstd＝3，Ystd＝3时，S为
Figure PCTCN2015083474-appb-000126
与S2一样；当符号Sstd为1+3i，即Xstd＝1，Ystd＝3时，S为
Figure PCTCN2015083474-appb-000127
其相当于对S2做水平翻转；当符号Sstd为1+1i，即Xstd＝1，Ystd＝1时，S为
Figure PCTCN2015083474-appb-000128
其相当于对S2做180°变化(既垂直翻转又水平翻转)，其他情况可以类似得到。
图14是根据本发明实施例的多用户信息传输的叠加装置的结构框图。如图14所示，该多用户信息传输的叠加装置可以包括：调制模块10，设置为将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；叠加模块20，设置为采用第一复数符号序列与第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，第三复数符号序列具有Gray映射属性；发送模块30，设置为根据第三复数符号序列形成发射信号，并将发射信号发送至多个接收机。
采用如图14所示的装置，解决了相关技术中的多个用户信号直接相加最终组合出的星座点没有Gray映射属性的的问题，进而在NOMA下行广播通信系统中简化了SIC接收机，使得接收端尽可能地进行符号级的SIC解调，同时使叠加后的符号又具有Gray属性，且可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入性能。
优选地，如图15所示，调制模块10可以包括：第一调制单元100，设置为将两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第一功率调整因子得到第一复数符号序列；第二调制单元102，设置为将两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第二功率调整因子得到第二复数符号序列；其中，第一复数符号序列的长度包括： 1，第二复数符号序列的长度包括：1，第一功率调整因子大于第二功率调整因子，第一复数符号序列的调制阶数低于或等于第二复数符号序列的调制阶数。
优选地，如图15所示，叠加模块20可以包括：获取单元200，设置为根据第一复数符号序列改变第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；叠加单元202，设置为将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列。
优选地，获取单元200可以包括：第一获取子单元(图中未示出)，设置为根据第一复数符号序列的实部取值确定变化后的符号序列的实部符号；第二获取子单元(图中未示出)，设置为根据第一复数符号序列的虚部取值确定变化后的符号序列的虚部符号。
优选地，编码单元202，设置为将第一复数符号序列与变化后的符号序列进行叠加处理，生成第三复数符号序列可以包括以下方式之一：
方式一、第三复数符号序列为
Figure PCTCN2015083474-appb-000129
Figure PCTCN2015083474-appb-000130
方式二、第三复数符号序列为
Figure PCTCN2015083474-appb-000131
Figure PCTCN2015083474-appb-000132
其中，
Figure PCTCN2015083474-appb-000133
为第一复数符号序列，
Figure PCTCN2015083474-appb-000134
为第二复数符号序列，
Figure PCTCN2015083474-appb-000135
或者
Figure PCTCN2015083474-appb-000136
Figure PCTCN2015083474-appb-000137
为变化后的符号序列，Xstd+Ystd·i为与第一复数符号序列对应的未归一化的整数格点星座符号，包括：BPSK对应的Xstd取值为{1，-1}，Ystd取零；QPSK对应的Xstd、Ystd取值为{1，-1}；16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}；
Figure PCTCN2015083474-appb-000138
为第一功率调整因子，
Figure PCTCN2015083474-appb-000139
为第二功率调整因子，
Figure PCTCN2015083474-appb-000140
表示向上取整，
Figure PCTCN2015083474-appb-000141
表示向下取整。
优选地，如图15所示，上述装置还可以包括：调整模块40，设置为通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列进行调整；或者，通过调整第一功率调整因子和/或第二功率调整因子对第三复数符号序列映射的星座图进行调整。
优选地，如图15所示，上述装置还可以包括：生成模块50，设置为根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成两个比特信息流，其中，两个用户信息中的第一用户信息流的保护优先级大于两个用户信息中的第二用户信息流的保护优先级。
图16是根据本发明实施例的多用户信息传输的解调装置的结构框图。如图16所示，该多用户信息传输的解调装置可以包括：接收模块60，设置为接收来自于发射机的发射信号，其中，发射信号是在发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用第一复数符号序列与第二复数符号序列进行叠加处理生成第三复数符号序列之后，根据第三复数符号序列形成的，第三复数符号序列具有Gray映射属性；解调模块70，设置为根据自身类型采用对应的解调方式对接收信号进行解调。
优选地，如图17所示，解调模块70可以包括：第一解调单元700，设置为在确定自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；第一解码单元702，设置为从第一部分信号中解码出与小区边缘用户对应的用户信息。
优选地，如图17所示，解调模块70可以包括：第二解调单元704，设置为在确定自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；第三解调单元706，设置为对接收信号中的第一部分信号进行去除，并从剩余的部分信号中解调出待发送至小区中心用户的第二部分信号；处理单元708，设置为根据第一部分信号改变第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；第二解码单元710，设置为从变化后的第二部分信号中解码出与小区中心用户对应的用户信息。
在优选实施过程中，各个用户接收发射信号所使用的信道的时频资源相同且重叠使用。
从以上的描述中，可以看出，上述实施例实现了如下技术效果(需要说明的是这些效果是某些优选实施例可以达到的效果)：采用本发明实施例所提供的技术方案，在NOMA下行广播通信系统中对SIC接收机进行简化，使接收端尽可能地实现符号级的SIC解调，同时又能够使得叠加后的符号又具有Gray属性，且可以简单、灵活地实现不同数据流分配不同的功率，提高多址接入的性能。
显然，本领域的技术人员应该明白，上述的本发明的各模块或各步骤可以用通用的计算装置来实现，它们可以集中在单个的计算装置上，或者分布在多个计算装置所 组成的网络上，可选地，它们可以用计算装置可执行的程序代码来实现，从而，可以将它们存储在存储装置中由计算装置来执行，并且在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤，或者将它们分别制作成各个集成电路模块，或者将它们中的多个模块或步骤制作成单个集成电路模块来实现。这样，本发明不限制于任何特定的硬件和软件结合。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
工业实用性
如上所述，本发明实施例提供的一种多用户信息传输的叠加、解调方法及装置具有以下有益效果：在NOMA下行广播通信系统中简化了SIC接收机，使得接收端尽可能地进行符号级的SIC解调，同时使叠加后的符号又具有Gray属性，且可以简单、灵活地实现为不同数据流分配不同的功率，提高多址接入性能。

Claims (22)

  1. 一种多用户信息传输的叠加方法，包括：
    将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；
    采用所述第一复数符号序列与所述第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，所述第三复数符号序列具有Gray映射属性；
    根据所述第三复数符号序列形成发射信号，并将所述发射信号发送至多个接收机。
  2. 根据权利要求1所述的方法，其中，将所述两个比特信息流分别调制成所述第一复数符号序列和所述第二复数符号序列包括：
    将所述两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一化的调制符号序列乘以第一功率调整因子得到所述第一复数符号序列；
    将所述两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一化的调制符号序列乘以第二功率调整因子得到所述第二复数符号序列；
    其中，所述第一复数符号序列的长度包括：1，所述第二复数符号序列的长度包括：1，所述第一功率调整因子大于所述第二功率调整因子，所述第一复数符号序列的调制阶数低于或等于所述第二复数符号序列的调制阶数。
  3. 根据权利要求1所述的方法，其中，采用所述第一复数符号序列与所述第二复数符号序列进行叠加处理，生成所述第三复数符号序列包括：
    根据所述第一复数符号序列改变所述第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；
    将所述第一复数符号序列与所述变化后的符号序列进行叠加处理，生成所述第三复数符号序列。
  4. 根据权利要求3所述的方法，其中，改变所述第二复数符号序列，获取所述变化后的符号序列包括：
    根据所述第一复数符号序列的实部取值确定所述变化后的符号序列的实部符号；
    根据所述第一复数符号序列的虚部取值确定所述变化后的符号序列的虚部符号。
  5. 根据权利要求3所述的方法，其中，将所述第一复数符号序列与所述变化后的符号序列进行叠加处理，生成所述第三复数符号序列包括以下之一：
    所述第三复数符号序列为
    Figure PCTCN2015083474-appb-100001
    Figure PCTCN2015083474-appb-100002
    所述第三复数符号序列为
    Figure PCTCN2015083474-appb-100003
    Figure PCTCN2015083474-appb-100004
    其中，
    Figure PCTCN2015083474-appb-100005
    为所述第一复数符号序列，
    Figure PCTCN2015083474-appb-100006
    为所述第二复数符号序列，
    Figure PCTCN2015083474-appb-100007
    或者
    Figure PCTCN2015083474-appb-100008
    Figure PCTCN2015083474-appb-100009
    为所述变化后的符号序列，Xstd+Ystd·i为与所述第一复数符号序列对应的未归一化的整数格点星座符号，包括：
    BPSK对应的Xstd取值为{1，-1}，Ystd取零；
    QPSK对应的Xstd、Ystd取值为{1，-1}；
    16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；
    64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}；
    Figure PCTCN2015083474-appb-100010
    为所述第一功率调整因子，
    Figure PCTCN2015083474-appb-100011
    为所述第二功率调整因子，
    Figure PCTCN2015083474-appb-100012
    表示向上取整，
    Figure PCTCN2015083474-appb-100013
    表示向下取整。
  6. 根据权利要求2所述的方法，其中，所述第三复数符号序列包括：
    通过调整所述第一功率调整因子和/或所述第二功率调整因子对所述第三复数符号序列进行调整；或者，
    通过调整所述第一功率调整因子和/或所述第二功率调整因子对所述第三复数符号序列映射的星座图进行调整。
  7. 根据权利要求2所述的方法，其中，在将所述两个比特信息流分别调制成所述第一复数符号序列和所述第二复数符号序列之前，还包括：
    根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成所述两个比特信息流，其中，所述两个用户信息中的第一用户信息流的保护优先级大于所述两个用户信息中的第二用户信息流的保护优先级。
  8. 一种多用户信息传输的解调方法，包括：
    接收来自于发射机的发射信号，其中，所述发射信号是在所述发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用所述第一复数符号序列与所述第二复数符号序列进行叠加处理生成第三复数符号序列之后，根据所述第三复数符号序列形成的，所述第三复数符号序列具有Gray映射属性；
    根据自身类型采用对应的解调方式对接收信号进行解调。
  9. 根据权利要求8所述的方法，其中，根据所述自身类型采用对应的解调方式对接收信号进行解调包括：
    在确定所述自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至所述小区边缘用户的第一部分信号；
    从所述第一部分信号中解码出与所述小区边缘用户对应的用户信息。
  10. 根据权利要求8所述的方法，其中，根据所述自身类型采用对应的解调方式对接收信号进行解调包括：
    在确定所述自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；
    对接收信号中的所述第一部分信号进行去除，并从剩余的部分信号中解调出待发送至所述小区中心用户的第二部分信号；
    根据所述第一部分信号改变所述第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；
    从所述变化后的第二部分信号中解码出与所述小区中心用户对应的用户信息。
  11. 根据权利要求8至10中任一项所述的方法，其中，各个用户接收所述发射信号所使用的信道的时频资源相同且重叠使用。
  12. 一种多用户信息传输的叠加装置，包括：
    调制模块，设置为将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列；
    叠加模块，设置为采用所述第一复数符号序列与所述第二复数符号序列进行叠加处理，生成第三复数符号序列，其中，所述第三复数符号序列具有Gray映射属性；
    发送模块，设置为根据所述第三复数符号序列形成发射信号，并将所述发射信号发送至多个接收机。
  13. 根据权利要求12所述的装置，其中，所述调制模块包括：
    第一调制单元，设置为将所述两个比特信息流中的第一信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第一功率调整因子得到所述第一复数符号序列；
    第二调制单元，设置为将所述两个比特信息流中的第二信息流经过功率归一化星座图调制后的功率归一的调制符号序列乘以第二功率调整因子得到所述第二复数符号序列；
    其中，所述第一复数符号序列的长度包括：1，所述第二复数符号序列的长度包括：1，所述第一功率调整因子大于所述第二功率调整因子，所述第一复数符号序列的调制阶数低于或等于所述第二复数符号序列的调制阶数。
  14. 根据权利要求13所述的装置，其中，所述叠加模块包括：
    获取单元，设置为根据第一复数符号序列改变所述第二复数符号序列在复平面的幅角，幅度保持不变，获取变化后的符号序列；
    叠加单元，设置为将所述第一复数符号序列与所述变化后的符号序列进行叠加处理，生成所述第三复数符号序列。
  15. 根据权利要求14所述的装置，其中，所述获取单元包括：
    第一获取子单元，设置为根据所述第一复数符号序列的实部取值确定所述变化后的符号序列的实部符号；
    第二获取子单元，设置为根据所述第一复数符号序列的虚部取值确定所述变化后的符号序列的虚部符号。
  16. 根据权利要求14所述的装置，其中，所述编码单元，设置为将所述第一复数符号序列与所述变化后的符号序列进行叠加处理，生成所述第三复数符号序列包括以下之一：
    所述第三复数符号序列为
    Figure PCTCN2015083474-appb-100014
    Figure PCTCN2015083474-appb-100015
    所述第三复数符号序列为
    Figure PCTCN2015083474-appb-100016
    Figure PCTCN2015083474-appb-100017
    其中，
    Figure PCTCN2015083474-appb-100018
    为所述第一复数符号序列，
    Figure PCTCN2015083474-appb-100019
    为所述第二复数符号序列，
    Figure PCTCN2015083474-appb-100020
    或者
    Figure PCTCN2015083474-appb-100021
    Figure PCTCN2015083474-appb-100022
    为所述变化后的符号序列，Xstd+Ystd·i为与所述第一复数符号序列对应的未归一化的整数格点星座符号，包括：
    BPSK对应的Xstd取值为{1，-1}，Ystd取零；
    QPSK对应的Xstd、Ystd取值为{1，-1}；
    16QAM对应的Xstd、Ystd取值为{1，-1，3，-3}；
    64QAM对应的Xstd、Ystd取值为{1，-1，3，-3，5，-5，7，-7}。
    Figure PCTCN2015083474-appb-100023
    为所述第一功率调整因子，为所述第二功率调整因子，
    Figure PCTCN2015083474-appb-100025
    表示向上取整，
    Figure PCTCN2015083474-appb-100026
    表示向下取整。
  17. 根据权利要求13所述的装置，其中，所述装置还包括：
    调整模块，设置为通过调整所述第一功率调整因子和/或所述第二功率调整因子对所述第三复数符号序列进行调整；或者，通过调整所述第一功率调整因子和/或所述第二功率调整因子对所述第三复数符号序列映射的星座图进行调整。
  18. 根据权利要求13所述的装置，其中，所述装置还包括：
    生成模块，设置为根据信道条件确定编码调制方式对两个用户信息流进行编码处理，生成所述两个比特信息流，其中，所述两个用户信息中的第一用户信息流的保护优先级大于所述两个用户信息中的第二用户信息流的保护优先级。
  19. 一种多用户信息传输的解调装置，包括：
    接收模块，设置为接收来自于发射机的发射信号，其中，所述发射信号是在所述发射机上将两个比特信息流分别调制成第一复数符号序列和第二复数符号序列，并采用所述第一复数符号序列与所述第二复数符号序列进行叠加处理 生成第三复数符号序列之后，根据所述第三复数符号序列形成的，所述第三复数符号序列具有Gray映射属性；
    解调模块，设置为根据自身类型采用对应的解调方式对接收信号进行解调。
  20. 根据权利要求19所述的装置，其中，所述解调模块包括：
    第一解调单元，设置为在确定所述自身类型为小区边缘用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至所述小区边缘用户的第一部分信号；
    第一解码单元，设置为从所述第一部分信号中解码出与所述小区边缘用户对应的用户信息。
  21. 根据权利要求19所述的装置，其中，所述解调模块包括：
    第二解调单元，设置为在确定所述自身类型为小区中心用户的情况下，从携带干扰信号的接收信号中直接解调出待发送至小区边缘用户的第一部分信号；
    第三解调单元，设置为对接收信号中的所述第一部分信号进行去除，并从剩余的部分信号中解调出待发送至所述小区中心用户的第二部分信号；
    处理单元，设置为根据所述第一部分信号改变所述第二部分信号在复平面的幅角，幅度保持不变，得到变化后的第二部分信号；
    第二解码单元，设置为从所述变化后的第二部分信号中解码出与所述小区中心用户对应的用户信息。
  22. 根据权利要求19至21中任一项所述的装置，其中，各个用户接收所述发射信号所使用的信道的时频资源相同且重叠使用。
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107370563A (zh) * 2016-05-13 2017-11-21 中兴通讯股份有限公司 信息传输方法及装置
CN107708196A (zh) * 2016-08-09 2018-02-16 上海诺基亚贝尔股份有限公司 通信方法、网络设备和终端设备

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016144100A1 (ko) 2015-03-09 2016-09-15 엘지전자 주식회사 무선 통신 시스템에서 신호를 송수신하는 방법 및 이를 수행하는 장치
US10212020B2 (en) 2015-06-09 2019-02-19 Samsung Electronics Co., Ltd Apparatus and method for superposition transmissions
JP2018526870A (ja) * 2015-07-10 2018-09-13 富士通株式会社 重複送信に基づくマルチユーザ重畳伝送方法、装置及びシステム
CN106487488A (zh) * 2015-08-25 2017-03-08 电信科学技术研究院 控制信令的发送、接收方法、网络设备及接收设备
WO2017039413A1 (ko) * 2015-09-03 2017-03-09 엘지전자 주식회사 무선 통신 시스템에서 비-직교 다중 접속을 이용하여 신호를 송수신하기 위한 방법 및 장치
CN109661786B (zh) * 2016-11-10 2020-04-14 华为技术有限公司 用于利用多址的无线通信的设备和方法
CN106936532B (zh) * 2017-02-24 2018-11-23 兰州大学 一种功率域非正交多址接入译码方法
CN108966333B (zh) * 2017-05-19 2020-09-08 华为技术有限公司 一种功率控制方法及设备
CN110071894B (zh) * 2018-01-22 2022-05-06 中兴通讯股份有限公司 一种信息处理方法和系统、发送装置及接收装置
CN113783821A (zh) * 2021-09-06 2021-12-10 中国科学院国家空间科学中心 一种基于功率复用的帧信令传输方法
CN114301754B (zh) * 2022-01-04 2024-02-06 哈尔滨工业大学 一种正交功率分层多址传输方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101541011A (zh) * 2008-03-20 2009-09-23 华为技术有限公司 一种协调方法、装置及用户设备
CN101627583A (zh) * 2006-05-17 2010-01-13 Lg电子株式会社 一种在无线通信系统中对前向链路实现叠加编码的方法
US20100195526A1 (en) * 2009-02-03 2010-08-05 Beceem Communications Inc. Multi-Stream Priority-Based Space-Time Coding
WO2014030501A1 (ja) * 2012-08-23 2014-02-27 三菱電機株式会社 通信システム、送信装置、受信装置およびディジタル伝送方法
CN104158631A (zh) * 2014-08-27 2014-11-19 北京邮电大学 一种数据流的发射方法及装置

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7418051B2 (en) * 2003-11-26 2008-08-26 Lucent Technologies Inc. Nonsystematic repeat-accumulate codes for encoding and decoding information in a communication system
EP1655877A1 (en) * 2004-11-03 2006-05-10 Matsushita Electric Industrial Co., Ltd. Method and transmitter structure reducing ambiguity by repetition rearrangement in the bit domain
EP2020158B1 (en) * 2006-04-25 2016-11-02 LG Electronics Inc. A method of configuring multiuser packet and a structure thereof in a wireless communication system
KR100964703B1 (ko) * 2006-05-19 2010-06-21 엘지전자 주식회사 효율적이고 효과적인 무선 통신을 위한 무선 자원을 이용하고 조작하는 방법
CN101083497B (zh) * 2006-05-30 2012-12-05 株式会社Ntt都科摩 多用户发送分集及中继方法和系统
US8259848B2 (en) * 2007-06-08 2012-09-04 Qualcomm Incorporated Hierarchical modulation for communication channels in single-carrier frequency division multiple access
US20100046644A1 (en) * 2008-08-19 2010-02-25 Motorola, Inc. Superposition coding
US8340202B2 (en) * 2010-03-11 2012-12-25 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for efficient soft modulation for gray-mapped QAM symbols
US8615703B2 (en) * 2010-06-04 2013-12-24 Micron Technology, Inc. Advanced bitwise operations and apparatus in a multi-level system with nonvolatile memory
CN103634072B (zh) * 2012-08-28 2017-11-03 华为技术有限公司 传输信息的方法和装置
CN105471543B (zh) * 2014-08-01 2020-08-14 株式会社Ntt都科摩 发送装置和发送方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101627583A (zh) * 2006-05-17 2010-01-13 Lg电子株式会社 一种在无线通信系统中对前向链路实现叠加编码的方法
CN101541011A (zh) * 2008-03-20 2009-09-23 华为技术有限公司 一种协调方法、装置及用户设备
US20100195526A1 (en) * 2009-02-03 2010-08-05 Beceem Communications Inc. Multi-Stream Priority-Based Space-Time Coding
WO2014030501A1 (ja) * 2012-08-23 2014-02-27 三菱電機株式会社 通信システム、送信装置、受信装置およびディジタル伝送方法
CN104158631A (zh) * 2014-08-27 2014-11-19 北京邮电大学 一种数据流的发射方法及装置

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107370563A (zh) * 2016-05-13 2017-11-21 中兴通讯股份有限公司 信息传输方法及装置
CN107370563B (zh) * 2016-05-13 2021-11-02 中兴通讯股份有限公司 信息传输方法及装置
CN107708196A (zh) * 2016-08-09 2018-02-16 上海诺基亚贝尔股份有限公司 通信方法、网络设备和终端设备
CN107708196B (zh) * 2016-08-09 2020-12-01 上海诺基亚贝尔股份有限公司 通信方法、网络设备和终端设备
US11412518B2 (en) 2016-08-09 2022-08-09 Nokia Solutions And Networks Oy Communication method, network device and terminal device

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