This application is a Continuation of U.S. patent application Ser. No. 16/751,946, filed on Jan. 24, 2020, which claims the priority benefit of U.S. Patent Application Ser. No. 62/796,994, filed on Jan. 25, 2019.

BACKGROUND

Aspects of the disclosure relate generally to wireless communication networks, and more particularly, to precoding multicarrier waveforms for orthogonal multiple access (OMA) or non-orthogonal multiple access (NOMA).

The background description includes information that may be useful in understanding the present inventive subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed inventive subject matter, or that any publication, specifically or implicitly referenced, is prior art.

Wireless communication systems provide various telecommunication services, such as telephony, video, data, messaging, and broadcasts. Wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, power). Typically, a wireless system reserves a sufficient amount of spectral resources to meet the system's peak demand, which seldom occurs. Thus, spectral resources are often under-utilized. Examples of multiple-access technologies include code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency divisional multiple access (SC-FDMA), and discrete Fourier transform spread orthogonal division multiplexing (DFT-s-OFDM). It should be understood that SC-FDM and DFT-s-OFDM are two names of essentially similar technologies, known as Carrier Interferometry (CI). However, DFT-s-OFDM is the terminology used in 3GPP specifications.

These multiple access technologies have been adopted in various telecommunication and wireless network standards. For example, fifth generation (5G) (also called New Radio (NR)) wireless access is being developed with three broad use case families in mind: enhanced mobile broadband (eMBB), massive or enhanced machine-type communications (MTC), and ultra-reliable low-latency communications (URLLC). Beyond 5G refers to visions for future generations of wireless communications (e.g., 5G-Advanced, 5G-Extreme, 6G) that enable groundbreaking high-bandwidth, low-latency, massive capacity, and massive connectivity. As demand for telecommunication and wireless access continues to increase, improvements in NR communications technology and beyond may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects.

To realize 5G and Beyond 5G, various technologies are proposed, including Massive multiple-input multiple output (MIMO), Cooperative MIMO, millimeter wave (mmWave) communications, NOMA, device-to-device (D2D), proximity services (ProSe), mobile relays, airborne relays, software-defined networking, fog computing, and distributed Artificial Intelligence (AI). Many infrastructure functions can be pushed to the network's edge to reduce latency, extend coverage, enhance versatility, and exploit the computational resources of the vast number of user devices. Mobile edge computing (MEC) can promptly process computationally intensive jobs offloaded from mobile devices, thus reducing end-to-end latency. Edge computing modules can be in a base transceiver stations (BTSs), relay, or user equipment (UE).

Aspects disclosed herein are broadly applicable to wireless standards and use case families disclosed herein, including (but not limited to) cellular, mobile broadband, vehicular ad-hoc networks, fixed broadband, Internet of Things (IoT), peer-to-peer networks, mesh networks, wireless personal area networks (WPANs), wireless local area networks (WLANs), wireless sensor networks, airborne networks, satellite networks, network fabrics, software-defined networks (SDNs), and hybrid networks.

In one aspect, a method of communication by a wireless device configured for communicating in a wireless network comprises spreading a data signal with at least one spreading code to produce a spread data signal; and modulating the spread data signal onto an OFDM signal to generate a discrete-time spread-OFDM signal to be transmitted in a communication link. The spreading can employ a function of a power-efficiency criterion for the wireless device or a spectral efficiency criterion for the communication link, for selecting one of a plurality of spreading code roll-off factors that provides the discrete-time spread-OFDM signal with a low Peak-to-Average-Power Ratio (PAPR).

An apparatus may include a means for spreading, a means for modulating, and a means for selecting one of a plurality of roll-off factors (e.g., pulse shapes) in the code space of the spread-OFDM signal based on the power-efficiency criterion for the wireless device or the spectral efficiency criterion for the communication link, such as described in the above method.

In another aspect, a method for wireless communication comprises encoding data bits of a first layer to a set of coded symbols; generating spread symbols using discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) spreading codes; and modulating the spread symbols onto a set of OFDM subcarrier frequencies to produce a discrete-time OFDM signal. The generating comprises mapping the coded symbols to a first sparse DFT-s-OFDM code space in a DFT-s-OFDM symbol, wherein the first sparse DFT-s-OFDM code space is different from a second sparse DFT-s-OFDM code space in the DFT-s-OFDM symbol, the second sparse DFT-s-OFDM code space being employed by a second layer. A sparse DFT-s-OFDM code space is a DFT-s-OFDM code space that has fewer than the total number of DFT-s-OFDM codes in a DFT-s-OFDM symbol.

An apparatus may include a means for encoding, a means for generating, and a means for modulating, wherein the means for generating includes a means for mapping the coded symbols to the first sparse DFT-s-OFDM code space in a DFT-s-OFDM symbol, such as described in the above method.

In another aspect, a method of communications comprises synthesizing a kernel waveform, wherein the kernel waveform has a sparse DFT-s-OFDM code space (i.e., a code space that has fewer than the total number of DFT-s-OFDM codes in a DFT-s-OFDM symbol); and performing a cyclic shift of the kernel waveform to produce a cyclic-shifted waveform having a DFT-s-OFDM code space that is different than the DFT-s-OFDM code space of the kernel waveform. The cyclic-shifted waveform may be transmitted in a communication channel; or may be modulated with data and transmitted; or may be combined with at least one other signal and transmitted. The kernel waveform may have a selectable pulse shape. An apparatus may include a means for synthesizing and a means for performing the cyclic shift, such as described in the above method. An apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory, wherein the instructions are operable to cause the processor to perform the above methods. A non-transitory computer-readable medium may include instructions operable to cause a processor to perform the above methods.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include determining occupancy or availability of resource blocks in the communication link, and the spectral efficiency criterion may be determined by listening to at least one of a random access channel, an uplink control channel, an uplink shared channel, a downlink control channel, or a downlink shared channel. The aforementioned channels may include a physical random access channel (PRACH), a physical downlink control channel (PDCCH), a physical downlinks channel (PDSCH), a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), or a physical control format indicator channel (PCFICH). Any of the aforementioned channels may be employed to communicate pulse-shaping and/or code-space information. Those of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those described, such as other traffic, control, and feedback channels. Some aspects provide for request and grant mechanisms for selecting and/or scheduling frequency-domain pulse shaping to be used, such as by a UE, BTS, or relay. Uplink and/or downlink grants may comprise DFT-s-OFDM code space grants, such as to enable multiple layers to share the same physical resource blocks (PRBs), also referred to as resource blocks.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may employ a downlink, an uplink, a relay link, or a peer-to-peer link; or wherein access to resources is grant-based or grant-free; or wherein the discrete-time spread-OFDM signal is transmitted by a BTS, a UE, a relay, or a cooperative group of wireless devices; or wherein the OFDM signal is configured for at least one of orthogonal multiple access and non-orthogonal multiple access. Code spaces within an OFDM symbol interval can be provisioned for any combination of uplink and downlink communications. Some aspects can switch between uplink and downlink based on the needs of the network, the needs of the devices, and the required communications flow in each direction.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may employ a spreading code roll-off factor that is one of a plurality of selectable spreading code roll-off factors, each of the plurality of spreading code roll-off factors providing for a different capacity when the OFDM signal comprises a fixed set of resource blocks; or wherein the spreading code roll-off factor is one a plurality of selectable spreading code roll-off factors that provide for a constant capacity when the OFDM signal comprises a variable set of resource blocks.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may be used in at least one of eMBB, MTC, URLLC, mmWave, D2D, ProSe, MEC, vehicular network communications, or IOT communications. D2D and ProSe includes use cases wherein a UE supports ProSe Discovery and/or ProSe Communication (e.g., a ProSe-enabled UE). 3GPP Services working group defined use cases and scenarios for ProSe in TR 22.803, which is incorporated by reference in its entirety. In this document, conditions for service flows and potential requirements for different use cases are analyzed to support D2D systems design.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, each layer can be assigned to its own sparse DFT-s-OFDM code space, and each layer may have its coded symbols transmitted thereon; or each layer can be assigned a unique identity symbol value, and each selected sparse DFT-s-OFDM code space may be selected for transmission based on one or more of the set of NOMA symbols, and each layer has its unique identity symbol value transmitted in the selected sparse DFT-s-OFDM code space.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, data symbols to be transmitted are NOMA symbols, and a first sparse DFT-s-OFDM code space is provisioned to overlap a second sparse DFT-s-OFDM code space; or the data symbols are Quadrature Amplitude Modulated symbols; or the first sparse DFT-s-OFDM code space is inside an OMA code-space subset of the DFT-s-OFDM symbol's full code space; or wherein the first sparse DFT-s-OFDM code space comprises a first DFT-s-OFDM code in a first DFT-s-OFDM symbol and at least a second DFT-s-OFDM code in a second DFT-s-OFDM symbol. The order of a sequence or block of symbols into a DFT spreader can provide for mapping particular symbols to particular DFT-s-OFDM codes. Thus, mapping each symbol to a particular code can be effected by selecting the order (i.e., where in the sequence or block each symbol is located). In some examples of the method, apparatus, and non-transitory computer-readable medium described above, sparse DFT-s-OFDM codes instead of the relatively short sparse code multiple access (SCMA) codes are configured to provide for higher spreading (processing) gain, improved frequency diversity, and/or SCMA-OFDM with improved power efficiency via PAPR-reduction.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above are anticipated to operate with D2D communication, which enables direct communication between two physically close terminals. D2D can be used for some ultra-low latency applications, as it provides a direct link between wireless devices without going through the network infrastructure. D2D might use inband or outband communication, where inband may use underlay inband D2D mode or overlay inband D2D mode. Aspects disclosed herein can be configured for Proximity Services (ProSe) operations, such as to provide for D2D, cooperative processing, smart industrial sensor networks, mobile sensor networks, mobile ad-hoc networks, vehicular ad-hoc networks, navigation sensor networks, mobile relay networks, cooperative content sharing, and content delivery in mobile radio networks.

In some examples of method, apparatus, and non-transitory computer-readable medium aspects, a receiver may employ a pulse-shaping filter configured to process pulse-shaped signals and/or a DFT-s-OFDM code space demultiplexer configured to demultiplex one or more layers that are sparsely distributed in a DFT-s-OFDM code space. Components in the examples of the method, apparatus, and non-transitory computer-readable medium described with respect to transmitter operations may have corresponding complementary components in receiver method, apparatus, and non-transitory computer-readable medium examples disclosed herein.

In some examples of method, apparatus, and non-transitory computer-readable medium aspects, individual transmissions from separate devices can produce a multiplexed data stream when received by a receiver. NOMA DFT-s-OFDM codewords include sparse DFT-s-OFDM codewords that overlap in the code space, and therefore can be identified upon reception of the multiplexed data stream using a low complexity algorithm, such as a message-passing algorithm (MPA), turbo decoder (TD), successive interference cancellation (SIC), maximum likelihood estimation (MLE), or an artificial neural network (ANN). In one aspect, the sparsity pattern of each sparse DFT-s-OFDM codeword uniquely identifies its layer, and the receiver estimates the data transmitted in each layer. In another aspect, each data symbol value is mapped (e.g., transformed) to a unique sparse DFT-s-OFDM codeword, and each layer is uniquely identified by an identity symbol value. The identity symbol value can be configured to be unique and separable from others when received at the receiver, which can be achieved by a BTS that carefully assigns identity symbol values to the layers based on channel state information (CSI) or received signal strength (RSS). The receiver can determine which layer(s) transmitted each data symbol, such as by using MPA, TD, SIC, MLE, or an ANN.

Groupings of alternative elements or aspect of the disclosed subject matter disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified, thus fulfilling the written description of all Markush groups used in the appended claims.

All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain aspect herein is intended merely to better illuminate the inventive subject matter and does not pose a limitation on the scope of the inventive subject matter otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the inventive subject matter.

All patent applications and patents mentioned in this disclosure are hereby incorporated by reference in their entireties: U.S. Pat. Nos. 8,670,390, 9,225,471, 9,270,421, 9,325,805, 9,473,226, 8,929,550, 7,430,257, 6,331,837, 7,076,168, 7,965,761, 8,098,751, 7,787,514, 9,673,920, 9,628,231, 9,485,063, patent application Ser. Nos. 10/145,854, 14/789,949, Pat. Appl. No. 62/197,336, patent application Ser. No. 14/967,633, Pat. Appl. No. 60/286,850, patent application Ser. Nos. 14/709,936, 14/733,013, 14/789,949, 13/116,984, 15/218,609, 15/347,415, 15/988,898, 16/021,001, 16/307,039, Pat. Appl. No. 62/510,987, Pat. Appl. No. 62/527,603, Pat. Appl. No. 62/686,083, Pat. Appl. No. 62/778,894, Pat. Appl. No. 62/662,140, Pat. Appl. No. 62/536,955, and PCT/US16/43852.

All publications disclosed herein are incorporated by reference in their entireties, including: J. S. Chow, J. M. Cioffi, J. A. C. Bingham; “Equalizer Training Algorithms for Multicarrier Modulation Systems,” Communications, 1993. ICC '93 Geneva. Technical Program, Conference Record, IEEE International Conference on; Vol: 2, 23-26 May 1993, pp. 761-765; Vrcelj et al. “Pre- and post-processing for optimal noise reduction in cyclic prefix based channel equalizers.” Communications, 2002. ICC 2002. IEEE International Conference on. Vol. 1. IEEE, 2002; LTE: Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation (3GPP TS 36.211 version 8.7.0 Release 8), 06/2009; LTE: Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (3GPP TS 36.212 version 8.8.0 Release 8), 01/2010; 3GPP TR 21.914 version 0.8.0 Release 14: Technical Specification Group Services and Systems Aspects; and 3GPP TR 21.915 version 0.5.0 Release 15: Technical Specification Group Services and Systems Aspects.

