阅读说明：本技术 非正交多址通信方法和系统 (Non-orthogonal multiple access communication method and system ) 是由 桑杰瓦.希拉斯 阿里瑞扎·白野斯特 贾明 马江镭 于 2018-05-16 设计创作，主要内容包括：在调制和资源元素(RE)映射之前可以执行比特级操作,以使用标准(QAM、QPSK、BPSK等)调制器生成NoMA传输。这样,利用比特级操作以很低的信号处理和硬件实现复杂度实现了NoMA的优势(例如,提高频谱效率、降低开销等)。比特级操作被具体设计为产生比输入比特流长、并包括可以作为输入比特值的函数计算的输出比特值的输出比特流,使得当对输出比特流进行调制(例如,m进制QAM、QPSK、BPSK)时,得到的符号模拟通过NoMA调制器或通过符号域扩展操作从输出比特流生成的扩展操作。(Bit-level operations may be performed prior to modulation and Resource Element (RE) mapping to generate a NoMA transmission using a standard (QAM, QPSK, BPSK, etc.) modulator. In this way, the advantages of NoMA (e.g., improved spectral efficiency, reduced overhead, etc.) are achieved with very low signal processing and hardware implementation complexity using bit-level operations. The bit-level operations are specifically designed to produce an output bitstream that is longer than the input bitstream and includes output bit values that can be calculated as a function of the input bit values, such that when the output bitstream is modulated (e.g., m-ary QAM, QPSK, BPSK), the resulting symbols mimic the spreading operations generated from the output bitstream by a NoMA modulator or by symbol domain spreading operations.)

1. A method of using bit-level operation to enable non-orthogonal multiple access (NoMA) communications using standard modulators, the method comprising:

a transmitter generating an output bitstream from an input bitstream according to a bit-level operation on the input bitstream such that a length of the output bitstream is greater than a length of the input bitstream, the input bitstream being an error detection/correction encoded bitstream;

the transmitter modulates the output bit stream according to the standard modulator to obtain a symbol sequence, wherein a value of at least one bit of the input bit stream is associated with at least two symbols of the symbol sequence, and wherein the standard modulator is one of: quadrature amplitude modulation QAM modulator, binary phase shift keying BPSK modulator,A modulator, and a quadrature phase shift keying QPSK modulator;

the transmitter mapping the symbol sequence to resource elements to obtain a NoMA signal; and

transmitting the NoMA signal to a receiver.

2. The method of claim 1, wherein the sequence of symbols comprises a plurality of different subsets of symbols, and at least two subsets are associated with different bits in the input bit stream.

3. The method of any of claims 1-2, wherein the sequence of symbols comprises a plurality of different subsets of symbols, and a relationship between symbols in one of the plurality of different subsets of symbols depends on a value of a bit associated with the one subset.

4. The method of any of claims 1-2, wherein a relationship between symbols in the sequence of symbols is independent of bits in the input bit stream.

5. The method of any of claims 1 to 4, further comprising:

a forward error correction, FEC, encoder encodes the unmodified input bitstream to generate the error detection/correction encoded input bitstream.

6. The method of any one of claims 1-5, wherein transmitting the NoMA signal with the UE comprises transmitting the NoMA signal from a base station to the UE, or transmitting the NoMA signal from the UE to the base station.

7. The method of any one of claims 1-6, wherein different NoMA signals are transmitted to or by the same UE.

8. The method of any one of claims 1 to 6, wherein different NoMA signals are transmitted to or by different UEs.

9. The method of any of claims 1 to 8, further comprising:

sending an indication of a Multiple Access (MA) signature to a UE, the MA signature configuring the UE to operate using a particular bit level to distinguish uplink transmissions of the UE from uplink transmissions of other UEs.

10. The method of any of claims 1 to 9, further comprising:

sending an indication of a Multiple Access (MA) signature to a UE, the MA signature configuring the UE to use a particular bit-level operation to decode a downlink NoMA transmission.

11. An apparatus, comprising:

a processor; and

a non-transitory computer readable storage medium storing a program for execution by the processor, the program comprising instructions to:

generating an output bitstream from an input bitstream according to a bit-level operation on the input bitstream such that a length of the output bitstream is greater than a length of the input bitstream, the input bitstream being an error detection/correction encoded bitstream;

modulating the output bit stream according to a standard modulator to obtain a sequence of symbols, wherein a value of at least one bit in the input bit stream is associated with at least two symbols in the sequence of symbols, and wherein the standard modulator is one of: quadrature amplitude modulation QAM modulator, binary phase shift keying BPSK modulator,A modulator, and a quadrature phase shift keying QPSK modulator;

mapping the symbol sequence to resource elements to obtain a NoMA signal; and

the non-orthogonal multiple access NoMA signal is transmitted to a receiver.

12. The apparatus of claim 11, wherein the sequence of symbols comprises a plurality of different subsets of symbols, and at least two subsets are associated with different bits in the input bit stream.

13. The apparatus of any of claims 11 to 12, wherein the sequence of symbols comprises a plurality of different subsets of symbols, and a relationship between symbols in one of the plurality of different subsets of symbols depends on a value of a bit associated with the one subset.

14. The apparatus according to any of claims 11 to 12, wherein the relationship between symbols in the sequence of symbols is independent of bits in the input bit stream.

15. The method of any of claims 11 to 14, wherein the program further comprises instructions to:

encoding the unmodified input bitstream using a forward error correction, FEC, encoder to generate the error detection/correction encoded input bitstream.

16. The device of any one of claims 11 to 15, wherein different NoMA signals are transmitted to or by the same user equipment, UE.

17. The device of any of claims 11-15, wherein different NoMA signals are transmitted to or by different user equipment, UEs.

18. The apparatus of any of claims 11 to 17, wherein the program further comprises instructions to:

sending an indication of a Multiple Access (MA) signature to a UE, the MA signature configuring the UE to operate using a particular bit level to distinguish uplink transmissions of the UE from uplink transmissions of other UEs.

19. The apparatus of any of claims 11 to 18, wherein the program further comprises instructions to:

sending an indication of a MA signature to a UE, the MA signature configuring the UE to use a particular bit-level operation to decode a downlink NoMA transmission.

20. A computer program product comprising a non-transitory computer readable storage medium storing a program, the program comprising instructions to:

generating an output bitstream from an input bitstream according to a bit-level operation on the input bitstream such that a length of the output bitstream is greater than a length of the input bitstream, the input bitstream being an error detection/correction encoded bitstream;

modulating the output bit stream according to a standard modulator to obtain a sequence of symbols, wherein a value of at least one bit of the input bit stream is associated with at least two symbols of the sequence of symbols, and wherein the standard modulator is one of: quadrature amplitude modulation QAM modulator, binary phase shift keying BPSK modulator,A modulator and a quadrature phase shift keying QPSK modulator;

mapping the symbol sequence to resource elements to obtain a NoMA signal; and

transmitting the NoMA signal to a receiver.

Technical Field

The present disclosure relates generally to wireless communications, and in particular embodiments to non-orthogonal multiple access communication methods and systems.

Background

Multiple access is a function of a wireless communication system in which multiple users can share resources. Multiple access systems may be orthogonal or non-orthogonal. In orthogonal multiple access systems, such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Orthogonal Frequency Division Multiple Access (OFDMA), signals of different users are transmitted on different material channel resources (e.g., time, frequency, or some combination). In non-orthogonal multiple access (NoMA) systems, such as Code Division Multiple Access (CDMA), interleaved multiple access (IDMA), interleaved multiple access (IGMA), multi-user shared access (MUSA), and Sparse Code Multiple Access (SCMA), cross-correlation of signals of different users may exist. Intentionally introducing non-orthogonality may improve spectral efficiency, but may create some challenges for transmitter and receiver implementations. There is a need to devise a non-orthogonal multiple access transmission scheme that simplifies and facilitates transmitter and receiver implementation.

Disclosure of Invention

Technical advantages are generally achieved by embodiments of the present disclosure describing methods and systems for non-orthogonal multiple access communication.

According to an embodiment, a method is provided for using bit-level operation to enable non-orthogonal multiple access (NoMA) communication using standard modulators. In this embodiment, the method includes generating an output bitstream from an input bitstream in accordance with a bit-level operation on the input bitstream such that a length of the output bitstream is greater than a length of the input bitstream. The input bitstream is an error detection/correction encoded bitstream. The method further comprises modulating said output bit stream according to said standard modulator to obtain a sequence of symbols. The value of at least one bit in the input bit stream is associated with at least two symbols in the sequence of symbols. The standard modulator is one of the following: quadrature amplitude modulation QAM modulator, binary phase shift keying BPSK modulator, A modulator, and a quadrature phase shift keying QPSK modulator. The method also includes mapping the symbol sequence to a resourceThe elements to obtain a NoMA signal, and transmitting the NoMA signal to a receiver. In one example, the symbol sequence includes a plurality of different subsets of symbols, and at least two subsets are associated with different bits in the input bit stream. In the same or another example, the sequence of symbols includes a plurality of different subsets of symbols, and a relationship between symbols in one of the plurality of different subsets of symbols depends on a value of a bit associated with the one subset. In any of the preceding examples or in another example, the relationship between symbols in the sequence of symbols is independent of bits in the input bitstream. In any preceding example or in another example, the method further comprises encoding the information bits by a forward error correction, FEC, encoder to generate the error detection/correction encoded input bitstream described above. In any one of the preceding examples or in another example, transmitting the NoMA signal with the UE includes transmitting the NoMA signal from a base station to the UE, or transmitting the NoMA signal from the UE to the base station. In any of the preceding examples or in another example, the different NoMA signals are transmitted to or by the same UE. In such an example, the individual NoMA signals may be transmitted using different NoMA signatures, each of which is assigned to the same UE as described above. In any of the preceding examples or in another example, the different NoMA signals are transmitted to or by different UEs. In any of the preceding examples or in another example, the method further comprises sending an indication of a multiple access, MA, signature to the UE, the MA signature configuring the UE to operate using a particular bit level to distinguish uplink transmissions of the UE from uplink transmissions of other UEs. In any of the preceding examples or in another example, the method further comprises sending an indication of a multiple access MA signature to the UE, the MA signature configuring the UE to use a particular bit level operation to decode a downlink NoMA transmission. Apparatus and computer program products for performing the above methods are also provided.

Drawings

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an embodiment wireless communication network;

fig. 2 is a schematic diagram of a conventional NoMA transmitter relying on a NoMA-specific modulator to generate a symbol sequence;

FIG. 3 is a schematic diagram of a NoMA transmitter of an embodiment using bit-level operation and a QAM modulator to generate a NoMA signal;

fig. 4 is a schematic diagram of another embodiment NoMA transmitter using bit-level operation and a QPSK modulator to generate a NoMA signal;

5A-5B are schematic diagrams of look-up tables corresponding to example bit level operations and exemplary constellations corresponding to the QPSK modulator of FIG. 4 for generating a sequence of symbols;

FIG. 6 is a flow diagram of an embodiment method for generating a NoMA signal using bit-level operations;

FIG. 7 is a flow diagram of an embodiment method of selecting a NoMA parameter;

FIG. 8 is a flow diagram of an embodiment method of transmitting a NoMA signal;

fig. 9 is a schematic diagram of another embodiment NoMA transmitter using bit-level operation and a QAM modulator to generate a NoMA signal;

fig. 10 is a schematic diagram of a lookup table corresponding to an example bit-level operation and an example constellation corresponding to the QAM modulator used to generate the symbol sequence in fig. 9;

fig. 11 is a schematic diagram of another embodiment NoMA transmitter using bit-level operation and a QPSK modulator to generate a NoMA signal;

fig. 12 is a schematic diagram of a look-up table corresponding to an example bit-level operation and an example constellation corresponding to the QPSK modulator used to generate a sequence of symbols in fig. 11;

fig. 13 is a schematic diagram of another embodiment NoMA transmitter using bit-level operation and a QPSK modulator to generate a NoMA signal;

fig. 14 is a schematic diagram of a look-up table corresponding to an example bit-level operation and an example constellation corresponding to the QPSK modulator used to generate a sequence of symbols in fig. 13;

fig. 15 is a schematic diagram of the proposed non-orthogonal multiple access strategy according to some embodiments;

fig. 16A is a schematic diagram of a transmitter for generating data symbols for transmission over a communication channel in accordance with some embodiments;

fig. 16B is a schematic diagram of a transmitter for generating data symbols for transmission over a communication channel in accordance with some embodiments;

fig. 16C is a schematic diagram of a transmitter for generating data symbols for transmission over a communication channel in accordance with some embodiments;

fig. 16D is a schematic diagram of a transmitter for generating data symbols for transmission over a communication channel in accordance with some embodiments;

fig. 16E is a schematic diagram of a transmitter for generating data symbols for transmission over a communication channel in accordance with some embodiments;

figure 17 is a schematic diagram of a constellation of two consecutive REs used in a 16-point SCMA codebook, in accordance with some embodiments;

FIG. 18 is a schematic diagram of how bit level scrambling, permutation, and interleaving may be used to implement a 16-point SCMA codebook using a standard 16-QAM modulator with Gray labeling (Gray labeling), according to some embodiments;

FIG. 19 is a schematic diagram of symbol sequence generation by a component spreading matrix, according to some embodiments;

FIG. 20A is a schematic diagram of an example SCMA-4 point codebook, in accordance with some embodiments;

FIG. 20B is a schematic diagram of an example SCMA-8 point codebook, in accordance with some embodiments;

fig. 21 is a schematic diagram of a transmitter for generating data symbols for transmission in a communication channel, in accordance with some embodiments;

fig. 22 is a schematic diagram of a transmitter for generating data symbols for transmission in a communication channel in accordance with other embodiments;

fig. 23A is a schematic diagram of a transmitter for generating data symbols for transmission in a communication channel, in accordance with other embodiments;

FIG. 23B is a schematic diagram of generating a 4-point SCMA codebook with symbol-dependent spreading, according to some embodiments;

figure 23C is a schematic diagram illustrating an example of a 4-point SCMA codebook generated by the symbol correlation extension of the embodiment of figure 23B, in accordance with some embodiments;

FIG. 23D is a schematic diagram illustrating generation of an 8-point SCMA codebook by symbol-level scrambling in accordance with some embodiments;

fig. 24 is a schematic diagram of the use of different multiple access signatures in an original transmission and subsequent retransmissions in accordance with some embodiments;

FIG. 25 is a block diagram of an embodiment processing system for performing the methods described herein;

fig. 26 is a block diagram of a transceiver adapted to send and receive signaling over a telecommunications network according to an example embodiment described herein.

Detailed Description

The making and using of embodiments of the present disclosure are discussed in detail below. It should be understood, however, that the concepts disclosed herein may be practiced in a variety of specific environments and that the specific embodiments discussed herein are merely illustrative and are not intended to limit the scope of the claims. Further, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Conventional non-orthogonal multiple access (NoMA) transmitters typically require the inclusion of one or more NoMA-specific operations in the transmission chain. These NoMA-specific operations may involve modifying operations in existing modules and conventional orthogonal multiple access transmitters, or may involve adding other modules and operations in addition to existing modules and operations in conventional orthogonal multiple access transmitters. NoMA-specific operations may apply MA signatures to signals prior to transmission to facilitate multi-stream detection. As used herein, the term "MA signature" refers to transmitter operations that generate a layer/stream-specific NoMA signal based on one or more stream-specific characteristics, which enables the NoMA signal to be multiplexed with other NoMA signals transmitted over the same set of resource elements, such that each NoMA signal can be decoded using multi-stream detection techniques at a respective receiver. It should be appreciated that the MA signature may take different forms depending on the multiple access scheme implemented. For example, if linear spreading is used, the MA signature may correspond to a spreading sequence. As another example, the MA sequence may correspond to symbols of an interleaving pattern (bit field or symbol field) or a resource mapping pattern.

A complex NoMA scheme may be implemented using a nonstandard NoMA-specific modulator that directly converts a bit stream into data symbols having the properties required for a particular NoMA scheme. However, the hardware implementation of non-standard NoMA-specific modulators is much more complex than traditional hardware implementations using standardized modulators, such as Quadrature Amplitude Modulation (QAM), Binary Phase Shift Keying (BPSK), etc,A modulator, and quadrature phase shift keying (QPSK, also known as 4-QAM). Thus, NoMA-specific modulators may not be suitable for many practical applications due to the added complexity and expense. Thus, the use of standard modulators (e.g., BPSK modulators, etc.) has historically been required,QPSK, 16-QAM, 64-QAM, 256-QAM, etc.) have been reluctant to employ advanced NoMA implementations, although there are considerable theoretical performance advantages to NoMA implementations. The advantages of NoMA include improved spectral efficiency and reduced overhead, since NoMA generally increases the density of multiplex layers and multiplex connections, and provides more flexible resource allocation/usage and interference mitigation by reducing collisions.

As another example, some NoMA schemes are typically implemented using additional symbol domain operations in addition to the normal operations in the transmitter. In other words, even if the NoMA scheme is implemented using a standard modulator, some conventional NoMA schemes require additional processing of the symbols generated by the standard modulator. In many cases, these additional symbol field operations are complex or dedicated and may not be hardware implementation friendly.

Thus, the disclosed embodiments describe a hardware-friendly example of an advanced NoMA implementation that may be implementedAre easily and conveniently used in next generation standards to take advantage of the performance benefits achieved by the NoMA with little or no adverse impact on hardware complexity. The disclosed embodiments describe that can be used to use standard modulators (e.g., m-ary QAM, QPSK, BPSK, or) Techniques to achieve NoMA transmission capabilities. Additionally, the disclosed embodiments also describe techniques that may be used to implement NoMA transmission capabilities without complex or dedicated symbol domain operations.

In accordance with embodiments of the present disclosure, advanced NoMA schemes include a NoMA scheme that employs an operation referred to as "extension. In this disclosure, an extension is defined to include an operation that associates the value of one input bit in a transmission chain with two or more symbols generated in the transmission chain. That is, the value of the one input bit becomes associated with two or more symbols transmitted through the physical resource. Spreading may also be referred to as multi-dimensional modulation or multi-dimensional operation, where multiple instances (dimensions) of different subcarriers or symbols represent the spreading effect.

Extensions may also include informal subcategories such as linear extensions and non-linear extensions, which may be viewed as different subsets or overlapping subsets of operations, depending on how the operations are defined. The term "linear spreading" as used herein refers to transmitter operations that establish a relationship between symbols in a sequence of symbols that is independent of input bits in an input bit stream, such that changes in the input values do not affect the relationship between symbols. For example, an embodiment linear expansion technique may achieve a phase difference between two symbols that remains consistent across all combinations of input bit values. The term "non-linear spreading" refers to transmitter operations that establish a relationship between sequence numbers of a sequence of symbols that depends on input bit values in an input bit stream such that different relationships between symbols are formed for different combinations of input bit values.

Typically, these linear and non-linear spreading operations are implemented in the symbol domain using either non-standard NoMA-specific modulators or using additional NoMA-specific symbol domain operations. In one aspect, it is an object of the present application to achieve these linear and non-linear spreading operations in the bit domain rather than the symbol domain, and without the use of non-standard NoMA specific modulators.

While certain aspects of the present disclosure are particularly applicable to use with extended NoMA schemes, some methods of the present disclosure also generally provide benefits to other NoMA schemes, and thus, the present disclosure is not limited to any particular extension. In particular, aspects of the present disclosure also describe bit-domain implementations of generation of generic MA signatures that include other operations besides spreading, such as scrambling, interleaving, and the like.

Aspects of the present disclosure employ bit-level operations prior to modulation and Resource Element (RE) mapping to use standard (QAM, QPSK, BPSK, b,Etc.) the modulator generates the NoMA transmission. In this way, the benefits of NoMA are realized with bit-level operations with significantly reduced signal processing and hardware implementation complexity. The bit-level operations are specifically designed to produce an output bitstream that is longer than the input bitstream and includes output bit values calculated as a function of the input bit values such that when the output bitstream is being modulated (e.g., m-ary QAM, QPSK, b, c, d,) The resulting symbols mimic the spreading operation generated from the input bit stream by a NoMA specific modulator or by a symbol domain spreading operation.

The output bit stream is then divided into two or more subsets of output bits, which are modulated using one or more standard modulators to generate a sequence of two or more symbols, which together form/simulate a spread symbol sequence. In one embodiment, a subset of the output bits are modulated in parallel using two or more QAM modulators. In other embodiments, the subsets of output bits are sequentially modulated using the same QAM modulator. The symbol sequence may then be mapped to or spread over a set of REs to generate a NoMA signal, which may be transmitted to a corresponding receiver, e.g., a User Equipment (UE), a base station, etc. Generating the NoMA signal using bit-level operations in conjunction with QAM modulation and RE-to-symbol mapping reduces the complexity of NoMA signal generation because bit-level operations are easier to implement than symbol-level operations. In addition, using bit-level operations rather than NoMA-specific modulation increases flexibility in diversified NoMA signal generation, since bit-level processing can be implemented/updated in software with little or no modification to hardware. All of these reduced complexities may also be used to reduce the cost of designing and manufacturing NoMA-enabled transceiver chips. While many embodiments are described as implementing bit-level operations using a standard NoMA modulator, it should be understood that the bit-level operations provided herein may also be implemented using a non-standard NoMA modulator. These and other aspects are described in detail below.

Fig. 1 is a schematic diagram of a network 100 for transmitting data. Network 100 includes a base station 110 having a coverage area 101, a plurality of UEs 120, and a backhaul network 130. As shown, base station 110 establishes an uplink (dashed line) connection and/or a downlink (dotted line) connection with UE 120, which are used to carry data transmitted from UE 120 to base station 110, and vice versa. Data carried on the uplink/downlink connections may include data communicated between UEs 120, as well as data communicated to/from a remote end (not shown) over backhaul network 130. The term "base station" as used herein refers to any component (or collection of components) for providing wireless access to a network, such as an enhanced Node B (eNB), transmit/receive point (TRP), macrocell, femtocell, Wi-Fi Access Point (AP), or other wireless enabled device. The base station may provide wireless access according to one or more wireless communication protocols, such as 5th generation new radio (5G _ NR), Long Term Evolution (LTE), LTE-advanced (LTE-a), High Speed Packet Access (HSPA), Wi-fi802.11a/b/G/n/ac/ad/ax/ay, and so on. The term "UE," as used herein, refers to any component (or collection of components) capable of establishing a wireless connection with a base station, such as mobile devices, mobile Stations (STAs), and other wireless-enabled devices. In some embodiments, network 100 may include various other wireless devices, such as relays, low power nodes, and the like.

In a conventional orthogonal multiple access strategy, different physical resource elements (e.g., time, frequency, code, etc.) are used by data for different mobile devices carried on the uplink and downlink connections 150. While the orthogonal multiple access strategy is relatively simple and implementation efficient, the spectral efficiency is relatively poor. There is a need to implement friendly non-orthogonal multiple access methods to improve the spectral efficiency of wireless communication systems.

Fig. 2 is a schematic diagram of a conventional transmitter 200 that generates a NoMA signal using a NoMA-specific modulation technique. As shown, the conventional transmitter 200 includes a Forward Error Correction (FEC) encoder 210, a NoMA modulator 230, and a symbol to RE mapper 240. FEC encoder 210 generates bit stream 215, and bit stream 215 is forwarded to NoMA modulator 230. The NoMA modulator 230 may be a Sparse Code Multiple Access (SCMA) modulator, a MUSA, or a generator for generating the symbol sequence 235 based on the bitstream 215 such that at least one bit (e.g., b2, etc.) in the bitstream 215 and a symbol S in the symbol sequence 235₁And S₂Any other type of modulator associated. The terms "symbol sequence" and "symbol set" are used interchangeably herein to refer to symbols generated in parallel or sequentially by one or more modulators. The symbol sequence 235 is then sent to a symbol-to-RE mapper 240, which symbol-to-RE mapper 240 spreads the symbols in the symbol sequence 235 across a set of resource elements to generate a NoMA signal 245.

As discussed above, NoMA-specific modulators are relatively complex and therefore not suitable for some applications. The disclosed embodiments are in BPSK,QPSK, and/or QAM modulation preceded by a bit-level operation to generate a sequence of symbols using a standard QAM modulator.

FIG. 3 shows the combination of BPSK,A schematic diagram of an embodiment transmitter 300 in which QPSK, and/or QAM modulators 330, 331 use bit-level operations 320 to generate a NoMA signal 345. As shown, the exemplary transmitter 300 includes an FEC encoder 310, a bit-level processor 320, BPSK,QPSK, and/or QAM modulator 330, and symbol to RE mapper 340. FEC encoder 310 may be any encoder for generating an error detection/correction coded bit stream including, but not limited to, a Turbo encoder, a low-density parity-check (LDPC) encoder, and/or a polar encoder. The error detection/correction encoded bit stream may be a bitstream that includes error correction bits (e.g., parity bits, FEC bits, etc.) and/or error detection bits (e.g., Cyclic Redundancy Check (CRC) bits, etc.). FEC encoder 310 generates an input bitstream 315 and forwards input bitstream 315 to bit-level processor 320. The bit-level processor 320 performs bit-level operations on the input bitstream 315 to generate an output bitstream 325 that is longer than the input bitstream. The bit-level operation may be defined by a parameter i₁、i₂Definitions, which will be described in detail below. The bit-level operation uses Multiple Access (MA) signatures to enable multi-stream detection at the receiver. Thus, the bit-level operations mimic the symbol-domain operations of a NoMA-specific modulator, and thus are different from conventional bit-level operations, such as error correction, error detection, and rate matching bit-level operations, which operate to provide error correction, error detection, or coding gain operations in the bit-domain. The output bit stream 325 is then forwarded to BPSK,QPSK, and/or QAM modulator 330, where different subsets from output bit stream 325 are individually modulated to produce respective symbols in a sequence of symbols, which collectively form symbol sequence 335.

BPSK、QPSK, and/or QAM modulator 330 may comprise a single QAM modulator that modulates respective subsets of bits in a sequential manner to generate each respective symbol in symbol sequence 335. Or BPSK,QPSK, and/or QAM modulator 330 may comprise two or more BPSK,QPSK, and/or QAM modulator 330 modulates various subsets of the bits in a parallel manner to generate symbols in symbol sequence 335. QAM modulator 330 may comprise any BPSK,QPSK, and/or m-ary QAM modulators, such as 4-QAM, 8-QAM, 16-QAM, 64-QAM, 256-QAM. The symbol sequence 335 is then forwarded to a symbol-to-RE mapper 340, and the symbol-to-RE mapper 340 maps the respective symbol sequence to a set of REs to obtain a NoMA signal 345. The NoMA signal 345 is then transmitted to the receiver.

Fig. 4 is a schematic diagram of an embodiment transmitter 400 using a bit-level operation 420 in conjunction with parallel QPSK modulators 431, 432 to generate a NoMA signal 445. As shown, the embodiment transmitter 400 includes an FEC encoder 410, a bit-level processor 420, QPSK modulators 431, 432, and a symbol-to-RE mapper 440. FEC encoder 420 and symbol-to-RE mapper 440 may be configured similarly to FEC encoder 310 and symbol-to-RE mapper 340 in fig. 3. In this example, the FEC encoder 410 generates a signal comprising three bits (b)₀,b₁,b₂) And forwards the input bitstream 415 to the bit-level processor 420, the bit-level processor 420 performing a bit-level operation on the input bitstream 415 to generate a bitstream comprising four bits (c)₀,c₁,c₂,c₃) The output bitstream 425. The output bitstream 425 is then divided into two subsets of bits, namely (c)₀,c₁) And (c)₂,c₃) The two subsets are modulated by QPSKThe modulators 431, 432 modulate in parallel to generate two symbols, i.e. (respectively) S₁And S₂Together, these two symbols form a symbol sequence 435. It should be understood that in other examples, the subset of bits (c)₀,c₁)、(c₂,c₃) May be modulated serially by a single QPSK modulator. Symbol S₁、S₂And then mapped to a set of REs by a symbol-to-RE mapper 440 to obtain a NoMA signal 445, which NoMA signal 445 is transmitted to a receiver, e.g., a UE or a base station/NodeB.

Fig. 5A and 5B show the look-up tables 520, 570 and constellations 531, 532 used to generate the symbol sequence 435 in fig. 4. The look-up tables 520, 570 correspond to different bit-level operations for converting the input bitstream 415 into the output bitstream 425 at the bit-level processor 420, and associate different bit values of the input bitstream 415 with bit values of the resulting output bitstream 425 as resulting from performing the respective bit-level operations, and identify symbols S that would be obtained by modulating the resulting output bit values at the QPSK modulators 431, 432 according to the constellations 531, 532₁、S₂The corresponding value of (a). In particular, the lookup table 520 corresponds to bit level operations: c ═ f (b)₀,b₁,b₂)＝[b₀,b₁,b₁,b₂]＝[c₀,c₁,c₂,c₃]The lookup table 570 corresponds to bit-level operations: c ═ f (b)₀,b₁,b₂₎＝[b₀,b₁,(b₀ XOR b₂),b₂]＝[c₀,c₁,c₂,c₃) Where c is the output bit stream, b₀、b₁And b₂For input bit values of the input bit stream, XOR is an exclusive OR (XOR) gate, c₀、c₁、c₂And c₃Is the output bit value of the output bitstream c. The bit-level operations corresponding to the lookup table 520 may be represented in matrix form as follows:

the bit-level operations corresponding to the lookup table 570 may be represented in the form of a matrix as follows:

it should be appreciated that the bit-level operations reflected by the look-up tables 520, 570 are two of many bit-level operations that may be used in conjunction with the QPSK modulators 431, 432 to convert the input bitstream 415 to the output bitstream 425.

After processing the input bitstream 415 using bit-level operations, the resulting output bitstream 425 may then be split into two subsets of bits, namely [ c ]₀,c₁]And [ c)₂,c₃]The two subsets are QPSK modulated based on the constellations 531, 532 to produce symbol pairs S₁＝[c₀,c₁]And S₂＝[c₂,c₃]Corresponding symbols in (1). It should be appreciated that the constellations 531, 532 are provided as examples and that different constellation configurations may be used to modulate the output bit stream 425 to the symbol sequence S₁、S₂In (1).

The input bit value b of the input bitstream 415 when using the bit-level operation corresponding to the look-up table 520₁And symbol S₁、S₂And (4) associating. The input bit value b of the input bitstream 415 when using the bit-level operation corresponding to the look-up table 570_oAnd symbol S₁、S₂And (4) associating. It can be understood from this that the symbol S is operated on by means of bit levels₁And S₂Depends at least in part on the same input bit, which establishes the symbol S₁And symbol S₂The relationship between components of the MA signature, and can be utilized by the receiver to mitigate multi-user interference between the instantaneous NoMA signals and other NoMA signals transmitted over the same RE. In particular, the receiver may process the symbol S in an iterative manner using, for example, a Message Passing Algorithm (MPA)₁And S₂To generate each input bit b₀、b₁And b₂Log Likelihood Ratio (LLR). However, the device is not suitable for use in a kitchenThereafter, the LLRs for the three input bits may be sent to an FEC decoder for bit-level decoding, where the LLRs are further processed until b for each input bit₀、b₁And b₂A hard decision is made. It should be understood that in this example, the symbol S₁And S₂Depends on the input bit b₁So as to change b₁The value of (A) will influence S₁And S₂The relationship between them. This bit-related relationship between symbols of the NoMA signal is beneficial, providing an additional degree of freedom for multi-user detection.

Fig. 6 is a flow diagram of an embodiment method 600 that may be performed by a transmitter to generate a NoMA signal using bit-level operations and a QAM modulator. In step 610, the transmitter generates an input bitstream from the input bitstream according to a bit-level operation on the input bitstream, the bit-level operation being such that the length of the output bitstream is greater than the length of the input bitstream. The input bitstream is an error correction encoded bitstream comprising error detection bits, e.g. CRC bits. In some embodiments, the length of the output bit stream may be equal to the length of the input bit stream, such as when bit-level operations primarily model symbol domain scrambling. In step 620, the transmitter modulates the output bit stream according to an m-ary QAM modulator to obtain a sequence of symbols. A value of at least one bit in the input bit stream is associated with at least two symbols in the sequence of symbols. In step 630, the transmitter maps the symbol sequence to resource elements to obtain a NoMA signal. In step 640, the transmitter transmits the NoMA signal to a receiver, e.g., UE, base station/NodeB.

Embodiments of the present disclosure provide methods for generating a NoMA signal using bit-level operations in conjunction with an m-ary QAM modulator. The resulting output bit stream may be a function of the input bit stream, and different subsets of the bits in the output bit stream may be individually modulated using an m-ary QAM modulator to produce a sequence of symbols that are then mapped to REs via a symbol-to-RE mapper to generate a NoMA signal.