CN111434073B

CN111434073B - Wireless communication method, apparatus and computer-readable program storage medium

Info

Publication number: CN111434073B
Application number: CN201880078787.XA
Authority: CN
Inventors: 戴建强; 袁志锋
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2018-01-12
Filing date: 2018-01-12
Publication date: 2022-05-10
Anticipated expiration: 2038-01-12
Also published as: CN111434073A; WO2019136697A1

Abstract

A method of wireless communication includes modulating, spreading, and scrambling a signal to be transmitted in a non-orthogonal multiple access (NOMA) mode. The wireless communication method includes modulating bits to obtain a block of symbols. Each symbol block includes a plurality of modulated symbols. The method includes spreading the symbol blocks to obtain spread symbol blocks, wherein a number of the spread symbol blocks is an integer multiple of a number of the symbol blocks. The method also includes scrambling the block of spread symbols with a scrambling sequence.

Description

Wireless communication method, apparatus and computer-readable program storage medium

Technical Field

The present disclosure relates generally to digital wireless communications.

Background

Mobile telecommunications technology is pushing the world to an increasingly interconnected and networked society. Next generation systems and wireless communication technologies will need to support a wider range of application scenario characteristics and provide more complex and comprehensive access requirements and flexibility than existing wireless networks.

Long Term Evolution (LTE) is a standard developed by the third generation partnership project (3GPP) for wireless communication of mobile devices and data terminals. LTE-advanced (LTE-a) is a wireless communication standard that enhances the LTE standard. The fifth generation wireless system, referred to as 5G, further advances the LTE and LTE-a wireless standards and addresses the need to support higher data rates, large numbers of connections, ultra-low latency, high reliability, and other emerging services.

Disclosure of Invention

An exemplary embodiment discloses a wireless communication method. The example method includes modulating bits to obtain symbol blocks, wherein each symbol block includes a plurality of modulated symbols, spreading the symbol blocks to obtain spread symbol blocks, wherein the plurality of spread symbol blocks are integer multiples of the plurality of symbol blocks, and scrambling the spread symbol blocks for transmission using a scrambling sequence.

In some embodiments, the number of modulated symbols in each symbol block is one. In an exemplary embodiment, the number of modulated symbols in each symbol block is at least two.

In some embodiments, one or more scrambling sequences are used by user equipment located in the same cell region. In some embodiments, the same scrambling sequence is used by user equipment located in the same cell area that includes only one set of user equipment. In some embodiments, at least one scrambling sequence is used by user equipment located in the same cell region comprising more than one group of user equipment. In some embodiments, one or more scrambling sequences are preconfigured based on an identification of a cell region or an identification of a group of user equipment.

In one exemplary embodiment, the length of the scrambling sequence is equal to the number of blocks of spreading symbols. In some embodiments, the spreading of the symbol block is performed using a spreading sequence. In some embodiments, the spreading sequence comprises a complex sequence, a Walsh sequence, a Discrete Fourier Transform (DFT) sequence, a Zadoff-Chu (ZC) sequence, a pseudo-noise (PN) sequence, a sequence whose elements are from {1+ j, 1-j, -1+ j, -1-j }, or a sequence whose elements are from {1, -1, j, -j }. In some embodiments, the spreading sequence is selected from a pre-configured spreading sequence setting. In some embodiments, the preconfigured spreading sequence setting has a minimum average cross-correlation. In some embodiments, the spreading sequence is randomly selected.

In some embodiments, the spreading of the symbol block is performed using more than one spreading sequence.

In another exemplary embodiment, a wireless communication method is disclosed that includes receiving a signal comprising spread and scrambled symbol blocks, descrambling the scrambled symbol blocks using a descrambling sequence to recover the spread symbol blocks, despreading the spread symbol blocks to recover the symbol blocks, wherein the number of spread symbol blocks is an integer multiple of the number of symbol blocks, and generating bits by demodulating symbols from the symbol blocks.

In some embodiments, despreading of the symbol blocks is performed using a Matched Filter (MF), Zero Forcing (ZF), or Minimum Mean Square Error (MMSE) approach. In some embodiments, for one user equipment detection, only one matrix inversion calculation is done for MMSE despreading or ZF despreading.

In an exemplary embodiment, each block of symbols includes one modulated symbol. In some embodiments, each symbol block includes at least two modulated symbols.

In some embodiments, one or more descrambling sequences are used for user equipment located in the same cell region. In some embodiments, the same descrambling sequence is used for user equipment located in the same cell region comprising only one set of user equipment. In some embodiments, at least one descrambling sequence is used for user equipment located in the same cell region comprising more than one group of user equipment. In some embodiments, the length of the descrambling sequence is equal to the number of spreading symbol blocks.

Another exemplary method of wireless communication includes generating a transmission signal transmitted from a user equipment in a wireless communication network. The transmission signal includes symbol blocks, each symbol block including a plurality of modulated symbols. The transmission signal is the result of the spreading operation, thus making the number of spread symbol blocks an integer multiple of the number of symbol blocks. Further, the transmission signal is a result of performing a scrambling operation on the spread symbol block.

In yet another exemplary aspect, the above-described method is embodied in the form of processor executable code and stored in a computer readable program medium.

In yet another exemplary embodiment, an apparatus configured or operable to perform the above method is disclosed.

The above and other aspects and embodiments thereof are described in more detail in the accompanying drawings, the description and the claims.

Drawings

Fig. 1 shows an exemplary mobile user equipment and base station operating in a non-orthogonal multiple access (NOMA) wireless network.

Fig. 2A shows an exemplary embodiment of a block diagram implemented at the transmitter side in a user equipment using NOMA.

Figures 2B-2C show examples of spreading and scrambling operations implemented by user equipment using NOMA.

Fig. 2D shows some examples of the expansion operation.

Fig. 2E-2F show some examples of scrambling operations.

Fig. 2G shows a spreading sequence applied to a block of modulated symbols.

Fig. 3 illustrates another embodiment of spreading a plurality of modulated symbols.

Fig. 4 illustrates yet another embodiment of scrambling a plurality of modulated symbols.

Fig. 5 shows an exemplary flow diagram describing the modulation, spreading and scrambling process implemented at the transmitter side of the user equipment.

Fig. 6 shows an exemplary flow chart describing the demodulation, despreading and descrambling process implemented at the receiver side in a base station. .

Fig. 7 shows a block diagram of a user equipment 700 implementing the modulation, spreading and scrambling features.

Fig. 8 shows a block diagram of a base station 800 implementing demodulation, despreading, and descrambling features.

Detailed Description

Conventional wireless technologies use technologies such as Time Division Multiple Access (TDMA) or Orthogonal Frequency Division Multiple Access (OFDMA), where a single user may access orthogonal resource blocks such as time slots or frequency channels. In contrast, non-orthogonal multiple access (NOMA) is a technique that may be employed in 5G wireless networks to serve more than one user in each orthogonal resource block. Although the NOMA technique may improve spectral efficiency, the adoption of the NOMA technique may cause some technical drawbacks. For example, as further shown in fig. 1, multi-user interference may be introduced due to NOMA techniques.

Fig. 1 shows an exemplary mobile user equipment and base station operating in a non-orthogonal multiple access (NOMA) wireless network. The base station BS1(120a) communicates with the user equipments (105a), (110a) and (115 a). Similarly, base station BS2(120b) communicates with user equipment (105b), (110b), and (115b), and base station BS3(120c) communicates with user equipment (105c), (110c), and (115 c). The user equipments shown in figure 1 may access their respective base stations using NOMA or conventional radio technology. As mentioned above, multi-user interference may be introduced as a result of multiple user equipments using NOMA for multiple access. A user equipment operating in a NOMA radio environment may experience interference from other user equipments located in its own cell region or in neighbouring cell regions. For example, in fig. 1, a user equipment (105a) using non-orthogonal signals for radio access may be subject to interference from user equipments (110a), (105b), and (105c), which may also use non-orthogonal signals for radio access.

The interference experienced by a user equipment from another user equipment located in the same cell area may be referred to as intra-cell interference. Further, interference experienced by a user equipment from another equipment located in a neighboring cell may be referred to as inter-cell interference. As further explained herein, intra-cell interference and inter-cell interference may be mitigated by using spreading and scrambling functions, respectively. One benefit of using spreading and scrambling functions in a NOMA wireless environment is that existing receivers located in the base station are designed to perform the despreading and descrambling functions to effectively suppress interference. As a result, the base station receiver can support a large number of accesses of the user equipment.

In an Orthogonal Multiple Access (OMA) system, a user equipment may transmit a certain number of source bits per second per hertz for a given modulation type and code rate. For example, a user equipment in an OMA system may transmit a certain number of bits per resource element. In contrast, in a NOMA system, a user equipment may transmit a certain number of source bits per second per hertz, at certain times. For example, the user equipment may transmit a certain number of bits (e.g., x bits/(k × REs), (where x is the number of bits, k is a number of times greater than 1, and RE is the number of resource elements)) for each certain number of times multiplied by the number of resource elements. In some embodiments, as further shown in the following paragraphs, the value of k may be selected from a set comprising 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. For example, using the NOMA scheme, it is possible to transmit a fractional number (e.g., x/k) of bits per RE transmitted for transmission.

The exemplary embodiments describe a wireless communication method that generates a transmission signal having exemplary features for transmission from a user equipment in a wireless communication network. For example, the transmission signal may comprise blocks of symbols, wherein each block of symbols comprises a plurality of modulated symbols, the transmission signal may be the result of a spreading operation, such that the number of spread blocks of symbols is an integer multiple of the number of blocks of symbols, and the transmission signal may be the result of a scrambling operation performed on the blocks of spread symbols.

Fig. 2A shows an exemplary embodiment of a block diagram implemented at the transmitter side in a user equipment using NOMA. At modulation block 202, the encoded bits are modulated to obtain a block of symbols (202A in fig. 2A and 202C in fig. 2C). In some embodiments, the bits may be modulated by a quadrature modulation scheme such as a Quadrature Phase Shift Keying (QPSK) modulation scheme or a Quadrature Amplitude Modulation (QAM) scheme. Each symbol block includes a plurality of modulated symbols. As shown at 202A in fig. 2A, in some embodiments, the number of modulated symbols in each symbol block may be one or two. As shown at 202C in fig. 2C, in some other embodiments, the number of modulated symbols in each symbol block may include at least two modulated symbols.

In fig. 2A, at the spreading block 204, the symbol block is spread to obtain an extended symbol block 204 a. The user equipment may spread each modulation symbol 202a using a spreading sequence (further illustrated in fig. 2D). In the example shown, one modulation symbol is spread to four symbols. However, different spreading factors may be used. As shown in fig. 2A, spreading changes the number of modulation symbols, while scrambling does not change the number of input symbols (e.g., four spread symbols are scrambled to output four scrambled symbols). One benefit of the extension techniques described in this document is that more transport streams are multiplexed within the same time-frequency. Fig. 2D also shows the spreading sequence used by the spreading block 204, and fig. 2D shows the relationship between the number of symbol blocks spread and the number of symbol blocks.

FIG. 2D illustrates an example of an extended function implemented in the extension block 204 of FIG. 2A. The number of extended symbol blocks 204d may be an integer multiple of the number of symbol blocks. In some embodiments, the number of symbols 204d that are spread may be the length of the spreading sequence 208 multiplied by the number of symbol blocks. In some embodiments, the length k of the spreading sequence 208 may be an integer, which may be selected from any one of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16. In some embodiments, the spreading sequence may comprise a complex sequence. For example, the complex sequence may comprise at least some coefficients represented by complex or imaginary numbers (i).

Returning to fig. 2A, at scrambling block 206, a scrambling sequence may be used to scramble the block of spread symbols for transmission. In some embodiments, as further illustrated in fig. 2E, the length of the scrambling sequence may be equal to the number of spread symbol blocks. In such an embodiment, if x modulation symbols are spread to obtain (k · x) symbols, the (k · x) symbols may be scrambled to obtain (k · x) first symbols. A scrambling sequence of length (k · x) may be used to scramble (k · x) spread symbols. Thus, each symbol block may be scrambled by a corresponding scrambling sequence having the same length. In some embodiments, as further shown in fig. 2F, elements of a scrambling sequence of length (k · x) may be used to scramble one extended block of symbols. In some embodiments, the (k · x) length scrambling sequence may be generated by a cell-specific scrambler. For example, the spreading sequences may also be predefined sequences, and each spreading sequence may be used by one cell region. In this document, the operator "·" indicates point multiplication. In some embodiments, one or more scrambling sequences may be used by user equipment located in the same cell region, as explained further below. In some embodiments, two user equipments located in two adjacent cell regions may use different scrambling sequences. One benefit of the scrambling techniques described in this document is suppression of inter-cell interference.

Fig. 2E-2F show some examples of scrambling functions implemented in the scrambling block 206 of fig. 2A. In fig. 2E, scrambling sequence 206E uses eight lengths of scrambling sequences (r 1-r 8) to scramble eight spread symbols (s 1-s 8). In fig. 2F, elements of scrambling sequence 206F of length (k · x) may use (r1) to scramble a spread symbol block that includes eight spread symbols (s1 through s 8).

Examples are provided to further illustrate user equipment employing the modulation, spreading, and scrambling operations described in this document. As an example, a user equipment may use QPSK modulation to modulate twenty coded bits and obtain ten modulation symbols. Each modulation symbol may be spread by, for example, a four-length spreading sequence (k-4) to obtain 40 symbols. The four-length spreading sequence may be depicted as (c1, c2, c3, c 4). The four-length spreading sequence may comprise a complex sequence, e.g., (1, i, 1, i). In this example, 40 spread symbols may be scrambled to obtain 40 first scrambled symbols. A scrambling sequence of length k for the entire scrambling sequence can be described as (r1, r2, r3, r 4). Thus, the first symbol S can be described using the following equation:

S-S1- (c1, c2, c3, c4) - (r1, r2, r3, r4) or

S1- (r1, r2, r3, r4) · (c1, c2, c3, c4) where S1 indicates the modulation symbol. Operation s1 · (r1, r2, r3, r4) generates (s1 · r1, s1 · r2, s1 · r3, s1 · r 4). Then, operations (r1, r2, r3, r4) · (c1, c2, c3, c4) generate (r1 · c1, r2 · c2, r3 · c3, r4 · c 4). Operations r1 · c1 and s1 · r1 mean the multiplication of r1 and c1, and of s1 and r1, respectively.

Returning to fig. 2A, in some embodiments, after the encoded bits are modulated at modulation block 202 to obtain a block of symbols, the modulation symbols may be repeated a certain number of times before spreading block 204 performs the spreading operation. Continuing with the above-mentioned example, each modulation symbol may be repeated four times, thus obtaining a total of 40 modulated symbols. The 40 modulated symbols are spread by a spreading sequence (e.g., (c1, c2, c3, c 4)). A scrambling sequence of length k, such as (r1, r2, r3, r4) may then be used to scramble the spread modulated symbols. In this embodiment, the first symbol S may be described using the following equation:

S-S1- (c1, c2, c3, c4) - (r1, r2, r3, r4) or

S1 (r1, r2, r3, r4) (C1, C2, C3, C4) at the modulation block 202, the coded bits are modulated to obtain a block of symbols (202A in fig. 2A and 202C in fig. 2C). In some embodiments, the bits may be modulated by a Quadrature Phase Shift Keying (QPSK) modulation scheme. Each symbol block includes a plurality of modulated symbols.

Fig. 2B illustrates an example of spreading and scrambling operations performed on one or more symbols as described in this patent document and as implemented by a user equipment using NOMA. For example, a four-length spreading sequence (c1, c2, c3, c4) is used to spread the four exemplary modulated symbols. Scrambling sequences such as (r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14, r15, r16) may be used to scramble the spread symbols and obtain the first symbols.

Fig. 2C shows an example of spreading and scrambling operations performed on symbol blocks as described in this patent document and implemented by a user equipment using NOMA. The block of symbols may comprise, for example, 12 modulated symbols. As shown in the example of fig. 2C, a four-length spreading sequence (C1, C2, C3, C4) is used to spread four exemplary symbol blocks, where each symbol block includes a plurality of modulated symbols. Scrambling sequences such as (r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14, r15, r16) may be used to scramble the spread symbol block and obtain the first symbol. In the embodiment of fig. 2C, all modulated symbols in one symbol block may be multiplied by one element of the scrambling sequence. An advantage of performing spreading and scrambling on a symbol block comprising at least two modulated symbols is that channel balancing and despreading can be performed together, and thus better performance can be obtained at the base station receiver end.

Fig. 2G shows a spreading sequence applied to a block of modulated symbols. In the example shown in fig. 2G, the coded bits are modulated using a QPSK modulation scheme to obtain a block of modulated symbols. Each element of the spreading sequence, such as (a1, a2, …, a4), may be applied to a block of modulated symbols to obtain a plurality of spread blocks of symbols. As depicted, each element of the spreading sequence may generate a portion of a block of spread modulation symbols that is contiguous along one of the time-frequency dimensions.

Fig. 3 illustrates another embodiment of spreading a plurality of modulated symbols. The modulation and spreading operations may be performed as described in this patent document to obtain (k · x) first symbols. The spreading sequence may be a dot product of the spreading sequence and the scrambling sequence. As an example, for a k value selected to be four, an exemplary spreading sequence may be described as follows:

(c1, c2, c3, c4) · (r1, r2, r3, r4) wherein the exemplary first symbol S can be described as:

s1- (c1, c2, c3, c4) (r1, r2, r3, r4) in some embodiments, point multiplication using a sequence may be inserted at one location of physical channel processing. Advantages may be interference suppression, diversity or reliability improvement.

Fig. 4 illustrates yet another embodiment of scrambling a plurality of modulated symbols. In this embodiment, after modulation, a plurality of symbols may be repeated k times to obtain (k · x) symbols. Using the scrambling operation described in this patent document, (k · x) symbols are scrambled to obtain (k · x) first symbols. In this embodiment, for a k value selected to be four, an exemplary scrambling sequence may be described as follows:

s ═ S1, S1, S1, S1 (c1, c2, c3, c4) · (r1, r2, r3, r4) in some embodiments, a user equipment may spread its modulation symbols using more than one spreading sequence. However, in some embodiments, the number of spreading sequences used by the user equipment may not be greater than eight due to considerations of receiver complexity. Referring back to fig. 2A, the encoded bits may be modulated to obtain a symbol block comprising a plurality of modulated symbols. The number of modulation symbols may be spread to obtain (k · x) symbols. The (k · x) symbols may be spread using more than one spreading sequence. As an example, a first set of modulated symbols can be spread using a first spreading sequence, and a second set of modulated symbols can be spread using a second spreading sequence. As a further example, a first spreading sequence may be used to spread the first half of the modulated symbols and a second spreading sequence may be used to spread the second half of the modulated symbols.

A scrambling function may then be performed on the spread symbol blocks including the symbol blocks spread using the first and second spreading sequences. A scrambling sequence of length (k · x) may be used to scramble (k · x) symbols. Each k-length symbol sequence may be scrambled by a corresponding k-length scrambling sequence.

In some embodiments, the plurality of source bits are encoded at a low coding rate, or the plurality of first coded bits are repeated k times to obtain coded bits. After the encoding or repetition, the plurality of encoded bits are modulated to obtain (k · x) modulation symbols. Using the scrambling operation described in this patent document, (k · x) symbols are scrambled to obtain (k · x) first symbols. In this embodiment, for a value of k that may be selected to be four, an exemplary scrambling sequence may be described as follows:

s ═ S1, S1, S1, S1) · (c1, c2, c3, c4) · (r1, r2, r3, r4) in some embodiments, multiple source bits are encoded at a low coding rate, or multiple first coded bits are repeated k times to obtain coded bits. After encoding or repetition, the plurality of encoded bits are scrambled using the techniques described in this patent document to obtain a plurality of scrambled bits, which are then modulated to obtain (k · x) first symbols.

In some embodiments, the plurality of source bits are encoded at a low coding rate, or the plurality of first coded bits are repeated k times or with an inserted space to obtain coded bits. After encoding or repeating or inserting spaces, a plurality of encoded bits are modulated to obtain (k · x) modulation symbols. The plurality of modulation symbols are interleaved to obtain (k · x) interleaved symbols. Using the scrambling technique described in this patent document, (k · x) symbols may be scrambled to obtain (k · x) first symbols. In some embodiments, the coded bits may be modulated by a Binary Phase Shift Keying (BPSK) modulation scheme.

In some embodiments, user equipment located in the same cell region may use one or more scrambling sequences. In this embodiment, the scrambling sequence may be preconfigured based on the identity of the cell or the identity of the group, or both. A group may comprise one or more user devices. Further, a cell region may include one or more groups of user equipment. In some embodiments, if a cell region contains only one set of user equipment, user equipment located in the same cell region may use the same scrambling sequence. In some embodiments, if a cell region includes more than one set of user equipment, then user equipment located in the same cell region may use at least one scrambling sequence.

In some embodiments, the spreading sequence may be selected from a pre-configured spreading sequence setting. In some embodiments, it may be advantageous to design the spreading sequences in a pre-configured spreading sequence arrangement to have a reduced average cross-correlation, e.g., a minimum average cross-correlation, between different sequences. In some embodiments, if the number of active user equipments is known in advance, a set of spreading sequences with the smallest average cross-correlation may be configured for the set of user equipments. Sequence set however, if the number of active user equipments is not known in advance, a set of spreading sequence settings may be configured for all user equipments in the cell, and each user equipment may randomly select a spreading sequence. In some embodiments, the spreading sequence may comprise a complex sequence, or a Walsh sequence, or a Discrete Fourier Transform (DFT) sequence, or a Zadoff-Chu (ZC) sequence, or a pseudo-noise (PN) sequence, or a sequence whose elements are from {1+ j, 1-j, -1+ j, -1-j } or a sequence whose elements are from {1, -1, j, -j }.

Fig. 5 shows an exemplary flow chart of a wireless communication procedure implemented in a user equipment. The processing may be used to generate a wireless transmission signal for transmission. At a modulation operation 502, bits are modulated to obtain a block of symbols. In some embodiments, each symbol block includes a plurality of modulated symbols. At an extension operation 504, the symbol block is extended to obtain an extended symbol block. The number of spreading symbol blocks may be an integer multiple of the number of symbol blocks. At a scrambling operation 506, a scrambling sequence may be used to scramble the spread symbol blocks for transmission. Various embodiments using the spreading and scrambling operations described with reference to fig. 2A through 2G, fig. 3, and fig. 4 may be used for this process. In some embodiments, the user equipment may perform the scrambling and spreading operations in one step, and may use, for example, a look-up table or circuitry that may implement the final scrambled spread signal.

Fig. 6 shows an exemplary flow chart describing the demodulation, despreading and descrambling processes implemented at the receiver side (e.g., in the receiver function of the base station). At receiving operation 602, a signal comprising a block of spread and scrambled symbols is received. At a descrambling operation 604, the scrambled symbol block is descrambled using a descrambling sequence to recover the extended symbol block. The base station may use one or more descrambling sequences for user equipment located in the same cell region. In some embodiments, the same descrambling sequence may be used for user equipment located in the same cell region that includes only one set of user equipment. Furthermore, in some embodiments, at least one descrambling sequence may be for user equipment located in the same cell region comprising more than one group of user equipment. In some embodiments, the length of the descrambling sequence may be equal to the number of spreading symbol blocks. At a despreading operation 606, the spread symbol blocks are despread to recover the symbol blocks. In some embodiments, despreading of the symbol blocks may be performed using a Matched Filter (MF), Zero Forcing (ZF), or Minimum Mean Square Error (MMSE) approach. In addition, for MMSE despreading or ZF despreading, only 1 matrix inversion calculation is done for one ue detection. If more spreading sequences are used by the user equipment, more matrix inversion calculations will be performed for MMSE despreading or ZF despreading for one user equipment detection. In some embodiments, the number of spreading symbol blocks may be an integer multiple of the number of symbol blocks. At generating operation 608, bits may be generated by demodulating symbols from the block of symbols. Various embodiments of the despreading and descrambling operations described with reference to figures 2A through 2G, figure 3 and figure 4 may be used for this process.

Fig. 7 shows a block diagram of a user equipment 700 implementing the modulation, spreading and scrambling features. The user equipment includes one or more processors 710, which may read code from memory 705 and perform operations associated with other blocks of the user equipment 700. The user equipment includes a transmitter 715 capable of transmitting NOMA or a conventional orthogonal access signal. The user equipment also includes a receiver 720 capable of receiving signals from the base station. The user equipment comprises a modulator 725 capable of modulating the bits using e.g. QPSK modulation. As described in this patent document, the module for spreading 730 spreads the modulated bits to obtain spread bits. The module for scrambling 735 may use a scrambling sequence to scramble the spread bits as described in this patent document.

Fig. 8 shows a block diagram of a base station 800 implementing demodulation, despreading, and descrambling features. The base station 800 includes one or more processors 810 that can read the code from the memory 805 and perform operations associated with other blocks of the base station 800. The base station includes a transmitter 815 capable of transmitting a signal to one or more user equipments. The base station also includes a receiver 820 capable of receiving NOMA or conventional orthogonal signals from one or more user equipment. As described in this patent document, the module for descrambling 835 can descramble the scrambled symbol block using a descrambling sequence to obtain an extended symbol block. A module for despreading 830 despreads the spread symbol blocks as described in this patent document to obtain symbol blocks. The base station also includes a demodulator 835 that can demodulate symbols from the symbol block.

The term "exemplary" is used to mean "an example", and does not imply an ideal or preferred embodiment unless otherwise indicated.

Some embodiments described herein are described in the broad context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. The computer readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), Compact Discs (CDs), Digital Versatile Discs (DVDs), and the like. Thus, a computer-readable medium may include a non-transitory storage medium. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer (or processor) executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Some of the disclosed embodiments, modules, and blocks may be implemented as devices or modules using hardware circuitry, software, or a combination thereof. For example, a hardware circuit implementation may include discrete analog and/or digital components that are integrated as part of a printed circuit board, for example. Alternatively or additionally, the disclosed components or modules may be implemented as Application Specific Integrated Circuits (ASICs) and/or as Field Programmable Gate Array (FPGA) devices. Some embodiments may additionally or alternatively include a Digital Signal Processor (DSP), which is a special purpose microprocessor having an architecture optimized for the operational requirements of digital signal processing associated with the disclosed functionality of the present application. Similarly, various components or sub-components within the various modules may be implemented in software, hardware, or firmware. Connections between modules and/or components within modules may be provided using any of a variety of connection methods and media known in the art, including, but not limited to, communications over the internet, wired or wireless networks using suitable protocols.

While this document contains many specifics, these should not be construed as limitations on the scope of the invention as claimed or as may be claimed, but rather as descriptions of features specific to particular embodiments of the invention. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

Only some embodiments and examples are described and other embodiments, enhancements and variations can be made based on what is described and illustrated in this disclosure. .

Claims

1. A method of wireless communication, comprising:

modulating bits to obtain symbol blocks, wherein each symbol block comprises at least two modulated symbols;

expanding the symbol blocks to obtain expanded symbol blocks, wherein the number of expanded symbol blocks is an integer multiple of the number of symbol blocks; and

scrambling the spread block of symbols with a scrambling sequence for transmission;

wherein the spreading of a symbol block is performed using a spreading sequence selected from a preconfigured set of spreading sequences having a minimum average cross-correlation;

wherein the same scrambling sequence is used for user equipments located in the same cell area comprising only one group of user equipments.

2. The wireless communication method of claim 1, wherein one or more scrambling sequences are used by user equipment located in the same cell region.

3. The wireless communication method of claim 1, wherein at least one scrambling sequence is used by user equipment located in a same cell region comprising more than one user equipment group.

4. The wireless communications method of claim 2, wherein the one or more scrambling sequences are preconfigured according to an identification of a cell region or an identification of a group of user equipment.

5. The wireless communication method of claim 1, wherein a length of the scrambling sequence is equal to a number of the spread symbol blocks.

6. The wireless communication method of claim 1, wherein the spreading sequence comprises a complex sequence, a Walsh sequence, a Discrete Fourier Transform (DFT) sequence, a Zadoff-chu (zc) sequence, a pseudo-noise (PN) sequence, a sequence whose elements are from {1+ j, 1-j, -1+ j, -1-j }, or a sequence whose elements are from {1, -1, j, -j }.

7. The wireless communication method of claim 1, wherein the spreading of the symbol block is performed using more than one spreading sequence.

8. A method of wireless communication, comprising:

receiving a signal comprising a block of spread and scrambled symbols;

descrambling the scrambled symbol block using a descrambling sequence to recover an extended symbol block;

despreading the spread symbol blocks to recover symbol blocks, wherein the number of spread symbol blocks is an integer multiple of the number of symbol blocks; and

generating bits by demodulating symbols from a block of symbols;

wherein spreading in the spread and scrambled symbol block is performed using a spreading sequence selected from a preconfigured set of spreading sequences having a minimum average cross-correlation;

wherein each symbol block comprises at least two modulated symbols;

wherein the same descrambling sequence is used for user equipments located in the same cell area comprising only one group of user equipments.

9. The wireless communication method of claim 8, wherein the despreading of the symbol blocks is performed using a Matched Filter (MF), Zero Forcing (ZF), or Minimum Mean Square Error (MMSE) method.

10. The wireless communication method of claim 9, wherein for one user equipment detection, only one matrix inversion calculation is done for MMSE despreading or ZF despreading.

11. The wireless communication method of claim 8, wherein one or more descrambling sequences are used for user equipment located in the same cell region.

12. The wireless communication method of claim 8, wherein at least one descrambling sequence is used for user equipment located in a same cell region comprising more than one group of user equipment.

13. The wireless communication method of claim 8, wherein a length of the descrambling sequence is equal to a number of the extended symbol blocks.

14. A method of wireless communication, comprising:

generating a transmission signal to be transmitted from a user equipment in a wireless communication network, wherein

Said transmission signal comprising symbol blocks, each of said symbol blocks comprising at least two modulated symbols,

the transmission signal is the result of a spreading operation, thus making the number of spread symbol blocks an integer multiple of the number of symbol blocks, an

The transmission signal is a result of a scrambling operation performed on the spread symbol block;

15. An apparatus for wireless communication comprising a memory and a processor, wherein the processor reads code from the memory and implements the method of any of claims 1-7 or 14.

16. A computer readable program storage medium having code stored thereon, which when executed by a processor, causes the processor to implement the method of any one of claims 1 to 7 or 14.

17. An apparatus for wireless communication comprising a memory and a processor, wherein the processor reads code from the memory and implements the method of any of claims 8 to 13.

18. A computer readable program storage medium having code stored thereon, which when executed by a processor causes the processor to implement the method of any one of claims 8 to 13.