WO2019157699A1

WO2019157699A1 - Techniques and apparatuses for time-domain spreading in non-orthogonal multiple access

Info

Publication number: WO2019157699A1
Application number: PCT/CN2018/076815
Authority: WO
Inventors: Jing LEI; Joseph Binamira Soriaga; Seyong PARK; Naga Bhushan; Renqiu Wang; Tingfang Ji; Yiqing Cao; Wanshi Chen
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2018-02-14
Filing date: 2018-02-14
Publication date: 2019-08-22
Anticipated expiration: 2020-08-14

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may select a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and process the data stream based at least in part on the hopping pattern. Numerous other aspects are provided.

Description

TECHNIQUES AND APPARATUSES FOR TIME-DOMAIN SPREADING IN NON-ORTHOGONAL MULTIPLE ACCESS

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication, and more particularly to techniques and apparatuses for time-domain spreading in non-orthogonal multiple access (NOMA) .

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) . A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , anew radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New radio (NR) , which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP) . NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In some aspects, a method for wireless communication performed by a user equipment (UE) may include selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and processing the data stream based at least in part on the hopping pattern.

In some aspects, a user equipment for wireless communication may include one or more processors configured to select a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and process the data stream based at least in part on the hopping pattern.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a user equipment, may cause the one or more processors to select a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and process the data stream based at least in part on the hopping pattern.

In some aspects, an apparatus for wireless communication may include means for selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and means for processing the data stream based at least in part on the hopping pattern.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, wireless communication device, and processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 2 is a block diagram conceptually illustrating an example of a base station in communication with a user equipment (UE) in a wireless communication network, in accordance with various aspects of the present disclosure.

Figs. 3A-3C are diagrams illustrating examples of time-domain spreading for NOMA, in accordance with various aspects of the present disclosure.

Fig. 4 is a diagram illustrating an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

In 5G/NR, some communications may use CP-OFDM with non-orthogonal multiple access (NOMA) . NOMA refers to transmission/reception schemes characterized by non-orthogonal, inter-UE resource allocation (e.g. time, frequency, code, space, etc. ) . One technique for achieving NOMA is resource spread multiple access (RSMA) . In general, NOMA can use a variety of waveforms, including CP-OFDM and DFT-s-OFDM, which may work on the uplink. CP-OFDM with NOMA may be used for both DL and UL transmission.

For a NOMA UE using CP-OFDM, a data tone transmission of the UE may be orthogonalized using OFDM. That is, the data tones belonging to a single UE will not interference with each other. Among multiple NOMA UEs belonging to the same cell, resource allocations of the multiple NOMA UEs are non-orthogonal. That is, data tones/spreading codes/time slots/spatial beams of the UEs will interfere with each other. This mutual interference may be controlled or configured by the NOMA codebook. At the receiver side, by invoking advanced algorithms for multi-UE detection, such controlled interference can be mitigated. As a result, the sum rate of NOMA can be enhanced.

However, some NOMA techniques, such as RSMA, may increase a peak-to-average power ratio (PAPR) of the waveform. This may be exacerbated as an overloading ratio of the waveform (e.g., a number of NOMA UEs divided by a spreading factor of the waveform) increases. A high PAPR is undesirable because an amplifier requires a higher backoff than for a low PAPR.

Techniques and apparatuses described herein may provide spreading techniques to reduce PAPR of the waveform. For example, some techniques and apparatuses described herein may provide for selection of a time-domain hopping pattern for selecting a short code to use to spread a data stream. In some aspects, different UEs may be assigned different hopping patterns, and the different hopping patterns may be configured to improve PAPR of the waveform. In this way, PAPR may be reduced, thereby permitting a lower transmit power backoff to be used for UEs.

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It is noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Fig. 1 is a diagram illustrating a network 100 in which aspects of the present disclosure may be practiced. The network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. Wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in Fig. 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the access network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Fig. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 Watts) .

A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, such as sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE) . UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed. In such a case, the RAT may use a NOMA configuration for radio access of UEs covered by the RAT.

In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity’s service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. This scheduling may be non-orthogonal in some cases (e.g., when using RSMA or another NOMA technique) .

Base stations are not the only entities that may function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (e.g., one or more other UEs) . In this example, the UE is functioning as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication. A UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may optionally communicate directly with one another in addition to communicating with the scheduling entity.

Thus, in a wireless communication network with a scheduled access to time–frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a BS 110 as an intermediary to communicate with one another) . For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like) , a mesh network, and/or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the BS 110.

As indicated above, Fig. 1 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 1.

Fig. 2 shows a block diagram of a design 200 of BS 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 1. BS 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and 5 ≥ 1.

At BS 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS (s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) , etc. ) and control information (e.g., CQI requests, grants, upper layer signaling, etc. ) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE 120, antennas 252a through 252r may receive the downlink signals from BS 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , reference signal received quality (RSRQ) , channel quality indicator (CQI) , etc.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, etc. ) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc. ) , and transmitted to BS 110. In some aspects, the transmit processor 264, the TX MIMO processor 266, and/or modulator 254 may encode or process the data based at least in part on a hopping pattern and/or a short code described herein.

At BS 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240. BS 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

In some aspects, one or more components of UE 120 may be included in a housing. Controller/processor 240 of BS 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with time-domain spreading for NOMA, as described in more detail elsewhere herein. For example, controller/processor 240 of BS 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 400 of Fig. 4 and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

The stored program codes, when executed by controller/processor 280 and/or other processors and modules at UE 120, may cause the UE 120 to perform operations described with respect to process 400 of Fig. 4 and/or other processes as described herein. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes; means for processing the data stream based at least in part on the hopping pattern; means for performing spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern; and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2.

While blocks in Fig. 2 are illustrated as distinct components, the functions described above with respect to the blocks may be implemented in a single hardware, software, or combination component or in various combinations of components. For example, the functions described with respect to the transmit processor 264, the receive processor 258, and/or the TX MIMO processor 266 may be performed by or under the control of controller/processor 280.

As indicated above, Fig. 2 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 2.

Figs. 3A-3C are diagrams illustrating examples 300 of time-domain spreading for NOMA, in accordance with various aspects of the present disclosure.

Fig. 3A shows an example of time-domain spreading for a CP-OFDM transmission. As shown by reference number 305, a UE 120 may obtain (e.g., receive, generate, determine, etc. ) a data stream. As shown by reference number 310, the UE 120 may select a hopping pattern of spreading codes. For example, the hopping pattern may identify a pattern for selecting a code (e.g., a spreading code) of a codebook that is to be applied to a corresponding symbol of the data stream. In some aspects, the hopping pattern may indicate that a first spreading code is to be applied for a first symbol, that a second spreading code is to be applied for a second symbol, and so on.

In some aspects, the hopping pattern may be specific to UE 120. For example, different UEs 120 may be assigned different hopping patterns (e.g., based at least in part on identifiers of the UEs 120 or a different means of assigning different hopping patterns) . As an example, assume that a set of UEs 120 are to use a codebook of size 6 (e.g., including 6 codewords for spreading codes) to perform spreading of respective data streams of the set of UEs 120. The codebook may be associated with indexes of {1 2 3 4 5 6} . In such a case, a first UE 120 may be associated with a hopping pattern of {1, 2, 3, 4, 5, 6} , a second UE 120 may be associated with a hopping pattern of {2, 3, 4, 5, 6, 1} , a third UE 120 may be associated with a hopping pattern of {3, 4, 5, 6, 1, 2} , and so on. In other words, each UE 120 may be associated with a different permutation of the code indexes of the codebook.

In this way, different spreading codes may be applied by different UEs 120 for each symbol of data streams for NOMA. Thus, PAPR of the different data streams may be reduced, thereby reducing a backoff performed for the UEs 120. Furthermore, this technique can be applied for various NOMA multiple-access schemes, such as resource spread multiple access, multi-user shared access, non-orthogonal coded multiple access, pattern division or interleaving based multiple access, and/or the like.

In some aspects, a UE 120 may select a subset of codewords within a codebook, such as C_x, C_y, C_z, wherein x, y, and z denote the index of the codeword within the codebook. The selection of {x, y, z} may be UE-specific. In some aspects, a UE 120 may arrange or order the subset of codewords in the order of C_x, C_y, C_z, and the ordering or permutation of the index set {x, y, z} may be UE-specific. In some aspects, the UE 120 may concatenate the subset of codewords periodically into [C_x C_y C_z] [C_x C_y C_z] [C_x C_y C_z] or a similar arrangement.

As shown by reference number 315, the UE 120 may perform spreading using short codes corresponding to codebook indexes identified by the hopping pattern. For example, in the above example, the first UE 120 may perform spreading of a first symbol using a codeword with the index 1, may perform spreading of a second symbol using a codeword with the index 2, and so on. Since each UE 120 is associated with a different permutation of the codebook, each UE 120 may apply a different short code with regard to a particular symbol. Thus, PAPR of the multiple-access waveform generated by the UEs 120 is reduced.

As shown by reference number 320, the UE 120 may perform serialization/parallelization (S/P) with regard to the processed data stream. As shown by reference number 325, the UE 120 may perform OFDM modulation with regard to the processed data stream. In some aspects, the UE 120 may transmit the processed data stream. In this way, the UE 120 generate a processed data stream using spreading techniques in a time domain, thereby reducing PAPR of the processed data stream.

Fig. 3B shows an example of time-domain spreading for a DFT-s-OFDM transmission. As shown in Fig. 3B, the UE 120 may receive or generate a data stream, as described in more detail in connection with Fig. 3A, above. As further shown, the UE 120 may select a hopping pattern, as also described in more detail in connection with Fig. 3A, above. As further shown, the UE 120 may perform spreading using a short code, identified based at least in part on the hopping pattern, in a time domain, as described in more detail in connection with Fig. 3A, above. As shown, the UE 120 may perform S/P with regard to the processed data stream, as described in more detail above.

As shown by reference number 330, the UE 120 may perform DFT spreading of the processed data stream, and, as shown by reference number 335, the UE 120 may perform zero padding of the processed data stream. For example, the UE 120 may apply DFT to the processed data stream to spread the processed data stream, and may perform zero padding with regard to the spread processed data stream. The UE 120 may perform OFDM modulation with regard to the processed data stream. In some aspects, the UE 120 may transmit the processed data stream. In this way, the UE 120 may process a data stream for NOMA transmission using DFT-s-OFDM and using a time-domain hopping pattern, which reduces PAPR of the data stream, particularly when multiple, different UEs 120 are to perform NOMA.

Fig. 3C shows examples of ordering and concatenation of codewords based at least in part on a spreading sequence. In Fig. 3C, each codeword of a codebook is represented by a rectangle with a different fill. Each symbol of a data stream is represented by d (n) (n is an integer) . As shown in the top half of Fig. 3C, in some aspects, a UE 120 may spread each data symbol using one of the short codewords identified by the codebook. For example, and as shown, the UE 120 may spread data symbols as follows: {C_x*d (1) } , {C_y*d (2) } , {C_z*d (3) } , {C_u*d (4) } , {C_v*d (5) } , {C_w*d (6) } . As shown in the bottom half of Fig. 3C, in some aspects, the UE 120 may spread each data symbol using a subset of concatenated codewords (e.g., {C_x*d (1) , C_y*d (1) } , {C_z*d (2) , C_u*d (2) } , {C_v*d (3) , C_w*d (3) } , and so on) . In some aspects (not shown) , the UE 120 may spread each data symbol using a concatenated codeword (e.g., {C_x*d (1) , C_y*d (1) , C_z*d (1) } , {C_u*d (2) , C_v*d (2) , C_w*d (2) } , and so on) . This may provide a larger processing gain with lighter NOMA loads.

As indicated above, Figs. 3A-3C are provided as examples. Other examples are possible and may differ from what was described with respect to Figs. 3A and 3B.

Fig. 4 is a diagram illustrating an example process 400 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 400 is an example where a UE (e.g., UE 120) performs time-domain spreading based at least in part on a hopping pattern for NOMA.

As shown in Fig. 4, in some aspects, process 400 may include selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain (block 410) . For example, the UE (e.g., using controller/processor 280 and/or the like) may select a hopping pattern for a data stream. In some aspects, the UE may receive information identifying the hopping pattern, and may select the hopping pattern based at least in part on the information. The data stream may be a data stream for which a spreading technique is to be performed using short codes, such as short codes of a codebook for NOMA. In some aspects, a short code may be referred to herein as a spreading sequence. The hopping pattern may be for spreading sequence selection, ordering, and concatenation in a time domain.

As shown in Fig. 4, in some aspects, process 400 may include processing the data stream based at least in part on the hopping pattern (block 420) . For example, the UE (e.g., using controller/processor 280 and/or the like) may process the data stream based at least in part on the hopping pattern. In some aspects, the UE may identify particular sequences or codewords based at least in part on which to perform spreading of particular symbols or portions of the data stream.

Process 400 may include additional aspects, such as any single aspect or any combination of aspects described below.

In some aspects, the UE may perform spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern. In some aspects, the hopping pattern is based at least in part on a permutation of a codeword index of a codebook. In some aspects, the hopping pattern is specific to the UE. In some aspects, a codebook that identifies the short spreading codes is for non-orthogonal multiple access. In some aspects, the data stream is to be transmitted using cyclic prefix orthogonal frequency division multiplexing (CP- OFDM) . In some aspects, the data stream is to be transmitted using discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .

Although Fig. 4 shows example blocks of process 400, in some aspects, process 400 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 4. Additionally, or alternatively, two or more of the blocks of process 400 may be performed in parallel.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term component is intended to be broadly construed as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software.

Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods, described herein, may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc. ) , and may be used interchangeably with “one or more. ” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication performed by a user equipment (UE) , comprising:

selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and

processing the data stream based at least in part on the hopping pattern.
The method of claim 1, wherein processing the data stream based at least in part on the hopping pattern further comprises:

performing spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern.
The method of claim 1, wherein the hopping pattern is based at least in part on a permutation of a codeword index of a codebook.
The method of claim 1, wherein the hopping pattern is specific to the UE.
The method of claim 1, wherein a codebook that identifies the short spreading codes is for non-orthogonal multiple access.
The method of claim 1, wherein the data stream is to be transmitted using cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) .
The method of claim 1, wherein the data stream is to be transmitted using discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .
A user equipment for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, the memory and the one or more processors configured to:

select a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and

process the data stream based at least in part on the hopping pattern.
The user equipment of claim 8, wherein the memory and the one or more processors, when processing the data stream based at least in part on the hopping pattern, are to:

perform spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern.
The user equipment of claim 8, wherein the hopping pattern is based at least in part on a permutation of a codeword index of a codebook.
The user equipment of claim 8, wherein the hopping pattern is specific to the user equipment.
The user equipment of claim 8, wherein a codebook that identifies the short spreading codes is for non-orthogonal multiple access.
The user equipment of claim 8, wherein the data stream is to be transmitted using cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) .
The user equipment of claim 8, wherein the data stream is to be transmitted using discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment, cause the one or more processors to:

select a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and

process the data stream based at least in part on the hopping pattern.
The non-transitory computer-readable medium of claim 15, wherein the one or more instructions, that cause the one or more processors to process the data stream based at least in part on the hopping pattern, further cause the one or more processors to:

perform spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern.
The non-transitory computer-readable medium of claim 15, wherein the hopping pattern is based at least in part on a permutation of a codeword index of a codebook.
The non-transitory computer-readable medium of claim 15, wherein the hopping pattern is specific to the user equipment.
The non-transitory computer-readable medium of claim 15, wherein a codebook that identifies the short spreading codes is for non-orthogonal multiple access.
The non-transitory computer-readable medium of claim 15, wherein the data stream is to be transmitted using cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) .
The non-transitory computer-readable medium of claim 15, wherein the data stream is to be transmitted using discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .
An apparatus for wireless communication, comprising:

means for selecting a hopping pattern for a data stream for which a spreading technique is to be performed using short codes, wherein the hopping pattern is for spreading sequence selection, ordering, and concatenation in a time domain; and

means for processing the data stream based at least in part on the hopping pattern.
The apparatus of claim 22, wherein the means for processing the data stream based at least in part on the hopping pattern further comprises:

means for performing spreading of symbols of the data stream using respective short spreading codes that are identified based at least in part on the hopping pattern.
The apparatus of claim 22, wherein the hopping pattern is based at least in part on a permutation of a codeword index of a codebook.
The apparatus of claim 22, wherein the hopping pattern is specific to the apparatus.
The apparatus of claim 22, wherein a codebook that identifies the short spreading codes is for non-orthogonal multiple access.
The apparatus of claim 22, wherein the data stream is to be transmitted using cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) .
The apparatus of claim 22, wherein the data stream is to be transmitted using discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .