Patent Description:
Examples of such multiple-access systems 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 (or multiplexing) (SC-FDMA) systems, and discrete Fourier transform spread orthogonal division multiplexing (DFT-s-OFDM) systems. It should be understood that SC-FDM and DFT-s-OFDM are two names of essentially similar technologies, however, DFT-s-OFDM is the terminology used in 3GPP specifications.

For example, a fifth generation (<NUM>) wireless communications technology (which can be referred to as new radio (NR)) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, <NUM> communications technology can include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, further improvements in NR communications technology and beyond may be desired.

For example, for NR communications technology, the NR physical layer includes physical channels encoded and transmitted on a single OFDM symbol. Examples of such physical channels include PDCCH on the downlink (DL), and short-PUCCH on the uplink (UL), and PDSCH/PUSCH in a 'mini-slot' transmission (where a mini-slot is a <NUM>-symbol slot). SC-FDM and/or DFT-s-OFDM versions of the same transmissions are also desirable, such as in UL link-budget limited case, and also in the DL for high carrier frequency (e.g., > <NUM>) transmissions. Also, a transmit diversity scheme may be desired for such transmissions.

Thus, improvements in wireless communications for NR technology and beyond may be desired.

<NPL> discusses channel estimation for timeslot structured single-carrier block transmission (SCBT) over space-, time-, and frequency-selective fading multiple-input multiple-output (MIMO) channels,.

<NPL> proposes an effective way of improving the performance of channel estimation for MIMO single-carrier Mock transmission (SCBT) systems.

<CIT> describes a method that allow reference and data-conveying modulations symbols to be multiplexed in the time domain to form an SC-FDM waveform.

<NPL> discusses phase tracking reference signals for CPE compensation in the context of a common framework.

<NPL> studied various methods to identify good training sequences for systems employing multiple transmit antennas over frequency-selective channels.

<NPL>, discloses a transmit diversity scheme over a single SC-FDM symbol and pilots for channel estimation.

The invention is set out in independent claims <NUM>, <NUM> and <NUM>.

Additionally, the term "component" as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software stored on a computer-readable medium, and may be divided into other components.

The present disclosure generally relates to using pilots inserted before the discrete Fourier transform (DFT) spreading as phase noise tracking reference signal (PTRS). More specifically, disclosed is an apparatus and method of splitting single symbol DFT-s-OFDM data and reference signal into two specially-formatted time domain signals to be transmitted over two antennas to enable transmit diversity. The present solution overcomes problems in combining DFT-s-OFDM and transmit diversity, in some aspects, by splitting the DFT-s-OFDM symbol to avoiding breaking the single-carrier property of the DFT-s-OFDM transmission, and by including the reference signal (e.g., a demodulation reference symbol (DMRS) or a PTRS) within each time domain signal to allow for separate channel estimation on each antenna.

Although the description herein and examples may refer to the case of two transmit antennas, it is clear that the same technique could be applied to more than two antennas. One approach to this is by grouping the antennas into pairs and applying the technique on each pair. Another approach is to split the single DFT-s-OFDM symbol into more than two sub parts, apply the space-time block coding (STBC) encoding across the resulting sub parts, and including a TDM RS (DMRS or phase noise tracking reference signal (PTRS)) for each transmit antenna, to create the transmitted signal for each transmit antenna.

In other non-claimed implementations, rather than being used for transmit diversity, the two specially-formatted time domain signals may be utilized instead to support user equipment (UE) multiplexing.

In another implementation, the two transmit antennas described above may be virtual antennas that are mapped to a physical antenna using a precoding matrix. In this case, the TDM separation of the reference signals from the two transmit antennas may be utilized for the virtual antennas but not for the physical antennas.

In a further implementation, when the above-described solution is applied to a single DFT-s-OFDM symbol, then no separate PTRS may be necessary. If the above-described solution is applied to multiple DFT-s-OFDM symbols, the above-described reference signal may be a PTRS, at least on a subset of DFT-s-OFDM symbols.

Additionally, in another non-claimed implementation, the input into a discrete Fourier transform (DFT) to create the DFT-s-OFDM symbols described above may instead be split and input into two smaller DFTs, whose outputs are multiplexed into a larger inverse discrete Fourier transform (IDFT). In this case, the two smaller DFTs by themselves would result in a single carrier waveform, however, the multiplexing makes the resulting waveform a multi-cluster transmission. In an aspect, the reference signal (e.g., DMRS or PTRS) can be inserted into each cluster.

Additional features of the present aspects are described in more detail below with respect to <FIG>.

It should be noted that the techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, DFT-s-OFDMA, and other systems. The terms "system" and "network" are often used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to <NUM> networks or other next generation communication systems).

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth, with the scope of protection being defined by the appended claims.

Referring to <FIG>, in accordance with various aspects of the present disclosure, an example wireless communication network <NUM> includes at least one UE <NUM> with a modem <NUM> having a signal processing component <NUM> having a signal coding/decoding scheme <NUM> that, in one aspect, is configured to generate and transmit, or alternatively to receive, a single-carrier waveform <NUM> from multiple transmit antennas including both a reference signal and data in a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol. As mentioned above, it should be understood that SC-FDM and DFT-s-OFDM are two names of essentially similar technologies, however, DFT-s-OFDM is the terminology used in 3GPP specifications. In another aspect, signal coding/decoding scheme <NUM> may be applied to multiple DFT-s-OFDM symbols, in which case the reference signal may be a phase noise tracking reference signal (PTRS). In a further, non-claimed aspect, signal coding/decoding scheme <NUM> may be modified such that the input is fed into two smaller discrete Fourier transforms (DFTs), and the outputs are multiplexed into a larger inverse DFT (IDFT), making a multi-cluster DFT output that may have reference signals in each cluster. In another aspect, signal coding/decoding scheme <NUM> may be further modified such that two time domain signals that are transmitted over different antennas for transmit diversity may be associated with one or more virtual antennas that are mapped to a physical antenna using a precoding matrix. In yet another, non-claimed aspect, instead of the two time domain signals being associated with two different transmit antennas, they may associated with different UE to support UE multiplexing. Thus, in general, the present aspects relate to using pilots inserted before the discrete Fourier transform (DFT) spreading as phase noise tracking reference signal (PTRS).

Further, wireless communication network <NUM> includes at least one base station <NUM> with a modem <NUM> having a signal processing component <NUM> with a signal coding/decoding scheme <NUM> complimentary to signal coding/decoding scheme <NUM> (and its aspects described above) on UE <NUM>. Signal coding/decoding scheme <NUM> is complimentary in the sense that it can receive and decode transmissions generated by signal coding/decoding scheme <NUM>, and/or it can generate and transmit similar transmissions as those described above for signal coding/decoding scheme <NUM>.

The wireless communication network <NUM> may include one or more base stations <NUM>, one or more UEs <NUM>, and a core network <NUM>. The core network <NUM> may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations <NUM> may interface with the core network <NUM> through backhaul links <NUM> (e.g., S1, etc.). The base stations <NUM> may perform radio configuration and scheduling for communication with the UEs <NUM>, or may operate under the control of a base station controller (not shown). In various examples, the base stations <NUM> may communicate, either directly or indirectly (e.g., through core network <NUM>), with one another over backhaul links <NUM> (e.g., X1, etc.), which may be wired or wireless communication links.

The base stations <NUM> may wirelessly communicate with the UEs <NUM> via one or more base station antennas. In some examples, base stations <NUM> may be referred to as a base transceiver station, a radio base station, an access point, an access node, a radio transceiver, a NodeB, eNodeB (eNB), gNB, Home NodeB, a Home eNodeB, a relay, or some other suitable terminology. The geographic coverage area <NUM> for a base station <NUM> may be divided into sectors or cells making up only a portion of the coverage area (not shown). The wireless communication network <NUM> may include base stations <NUM> of different types (e.g., macro base stations or small cell base stations, described below). Additionally, the plurality of base stations <NUM> may operate according to different ones of a plurality of communication technologies (e.g., <NUM> (New Radio or "NR"), fourth generation (<NUM>)/LTE, <NUM>, Wi-Fi, Bluetooth, etc.), and thus there may be overlapping geographic coverage areas <NUM> for different communication technologies.

In some examples, the wireless communication network <NUM> may be or include one or any combination of communication technologies, including a NR or <NUM> technology, a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) or MuLTEfire technology, a Wi-Fi technology, a Bluetooth technology, or any other long or short range wireless communication technology. In LTE/LTE-A/MuLTEfire networks, the term evolved node B (eNB) may be generally used to describe the base stations <NUM>, while the term UE may be generally used to describe the UEs <NUM>. The wireless communication network <NUM> may be a heterogeneous technology network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station <NUM> may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs <NUM> with service subscriptions with the network provider.

A small cell may include a relative lower transmit-powered base station, as compared with a macro cell, that may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access and/or unrestricted access by UEs <NUM> having an association with the femto cell (e.g., in the restricted access case, UEs <NUM> in a closed subscriber group (CSG) of the base station <NUM>, which may include UEs <NUM> for users in the home, and the like).

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A user plane protocol stack (e.g., packet data convergence protocol (PDCP), radio link control (RLC), MAC, etc.), may perform packet segmentation and reassembly to communicate over logical channels. For example, a MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat/request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and the base stations <NUM>. The RRC protocol layer may also be used for core network <NUM> support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs <NUM> may be dispersed throughout the wireless communication network <NUM>, and each UE <NUM> may be stationary or mobile. A UE <NUM> may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may be a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a smart watch, a wireless local loop (WLL) station, an entertainment device, a vehicular component, a customer premises equipment (CPE), or any device capable of communicating in wireless communication network <NUM>. Additionally, a UE <NUM> may be Internet of Things (IoT) and/or machine-to-machine (M2M) type of device, e.g., a low power, low data rate (relative to a wireless phone, for example) type of device, that may in some aspects communicate infrequently with wireless communication network <NUM> or other UEs. A UE <NUM> may be able to communicate with various types of base stations <NUM> and network equipment including macro eNBs, small cell eNBs, macro gNBs, small cell gNBs, relay base stations, and the like.

UE <NUM> may be configured to establish one or more wireless communication links <NUM> with one or more base stations <NUM>. The wireless communication links <NUM> shown in wireless communication network <NUM> may carry uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each wireless communication link <NUM> may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (reference signals, control channels, etc.), overhead information, user data, etc. In an aspect, the wireless communication links <NUM> may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type <NUM>) and TDD (e.g., frame structure type <NUM>). Moreover, in some aspects, the wireless communication links <NUM> may represent one or more broadcast channels.

In some aspects of the wireless communication network <NUM>, base stations <NUM> or UEs <NUM> may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations <NUM> and UEs <NUM>. Additionally or alternatively, base stations <NUM> or UEs <NUM> may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication network <NUM> may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. The base stations <NUM> and UEs <NUM> may use spectrum up to Y MHz (e.g., Y = <NUM>, <NUM>, <NUM>, or <NUM>) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x = number of component carriers) used for transmission in each direction. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The wireless communications network <NUM> may further include base stations <NUM> operating according to Wi-Fi technology, e.g., Wi-Fi access points, in communication with UEs <NUM> operating according to Wi-Fi technology, e.g., Wi-Fi stations (STAs) via communication links in an unlicensed frequency spectrum (e.g., <NUM>). When communicating in an unlicensed frequency spectrum, the STAs and AP may perform a clear channel assessment (CCA) or listen before talk (LBT) procedure prior to communicating in order to determine whether the channel is available.

Additionally, one or more of base stations <NUM> and/or UEs <NUM> may operate according to a NR or <NUM> technology referred to as millimeter wave (mmW or mmwave) technology. For example, mmW technology includes transmissions in mmW frequencies and/or near mmW frequencies. Extremely high frequency (EHF) is part of the radio frequency (RF) in the electromagnetic spectrum. For example, the super high frequency (SHF) band extends between <NUM> and <NUM>, and may also be referred to as centimeter wave. Communications using the mmW and/or near mmW radio frequency band has extremely high path loss and a short range. As such, base stations <NUM> and/or UEs <NUM> operating according to the mmW technology may utilize beamforming in their transmissions to compensate for the extremely high path loss and short range.

Referring to <FIG>, in one example from the transmission perspective, a first time domain transmission symbol vector <NUM> for a first antenna (TxAnt <NUM>) and a second time domain transmission symbol vector <NUM> for a second antenna (TxAnt <NUM>) are based on a first version (scheme <NUM>) <NUM> of signal coding/decoding scheme <NUM>. Further, in another example, a first time domain transmission symbol vector <NUM> for a first antenna (TxAnt <NUM>) and a second time domain transmission symbol vector <NUM> for a second antenna (TxAnt <NUM>) are based on a second version (scheme <NUM>) <NUM> of signal coding/decoding scheme <NUM>.

In each of first version (scheme <NUM>) <NUM> and second version (scheme <NUM>) <NUM>, the data represents a single DFT-s-OFDM data symbol that is split (e.g., prior to input to DFT-spreading, two symbols each with their own cyclic prefix are created), and then encoded according to a space-time block code (STBC), such as an Alamouti code, to create two time domain signals having spatial and temporal transmit diversity.

Additionally, a reference signal, such as a DMRS or a PTRS, may be inserted in each of the <NUM> split symbols that are created, as described above.

In first version (scheme <NUM>) <NUM>, the reference signal is transmitted only from one antenna on the first symbol, and from the other antenna in second symbol, which allows separate channel estimation for each antenna.

In contrast, in second version (scheme <NUM>) <NUM>, the reference signal is transmitted from both antennas on both symbols, but in a TDM fashion across the two antennas. Also, in this version, cyclic prefix also accounts for blank durations caused due to TDM. For example, TDM time allocations for the reference signal could be different in the two split symbols for each transmission, although the TDM time allocations maintain a total time across symbols to be same for both transmissions.

In some scenarios, second version (scheme <NUM>) <NUM> may be preferred. For example, distributing the reference signal over both symbols leads to better channel estimation in a high Doppler case.

Alternatively, in a low-Doppler case, all the reference signals can be placed prior to the first symbol. For instance, when the entire reference signal precedes all data, then channel estimation can begin earlier, which results in a better (more efficient) decoding timeline.

Thus, UE <NUM> operating signal processing component <NUM> and/or base station <NUM> operating signal processing component <NUM> according to either first version (scheme <NUM>) <NUM> or second version (scheme <NUM>) <NUM> of signal processing scheme <NUM> or signal processing scheme <NUM> can generate and transmit a single-carrier waveform from multiple transmit antennas including both a reference signal and data in a single-carrier frequency division multiplexing (DFT-s-OFDM) symbol.

Referring to <FIG>, an example method <NUM> of wireless communications includes, at block <NUM>, generating a single-carrier waveform for multiple transmit antennas including both a reference signal and data in a DFT-s-OFDM symbol. Additionally, at block <NUM>, method <NUM> further includes transmitting the single-carrier waveform across the multiple antennas.

According to the invention, the method <NUM> includes transmitting the reference signal from only a first antenna on a first symbol, and from only a second antenna on a second symbol, or transmitting the reference signal from both a first antenna and a second antenna on both of a first symbol and a second symbol and in a TDM fashion. In this option, a TDM time allocation for the reference signal may be different in each of the first symbol and the second symbol, although a total time of the TDM time allocation is the same across both the first symbol and the second symbol. Further, this option may include positioning all of the reference signal prior to the first symbol, or distributing the reference signal over both of the first symbol and the second symbol.

For example, in an aspect, the generating and transmitting of the single-carrier waveform may be performed by UE <NUM> operating signal processing component <NUM> and signal processing scheme <NUM>, and/or base station <NUM> operating signal processing component <NUM> and signal processing scheme <NUM> in conjunction with one or more processors, memories, transceivers, RF front ends, and antennas.

Further, for example, in some aspects the generating of the single-carrier waveform may include inputting N blocks of symbols (or at least the split symbols)(e.g., in time domain) into an N-point DFT to obtain a frequency domain representation of the input symbols, mapping each of the N DFT outputs to one of M (>N) orthogonal subcarriers that can be transmitted, resulting in a set of complex carrier amplitudes, performing an M-point inverse DFT (IDFT) to transform the complex carrier amplitudes to a complex time domain signal, where each complex time domain signal modules a single frequency carrier and all the symbols are transmitted sequentially. The receiver can utilize a reverse process to decode the received signal.

Accordin to the invention, the generating of the single-carrier waveform may include receiving a symbol sequence for transmission including the data and the reference signal, creating an DFT-s-OFDM data symbol for the data and an DFT-s-OFDM reference signal symbol for the reference signal, splitting the DFT-s-OFDM data symbol in to a first single carrier time domain (SC-TD) data symbol and a second SC-TD data symbol, splitting the DFT-s-OFDM reference signal symbol into a first SC-TD reference signal symbol and a second SC-TD reference signal symbol, applying a space-time block code (STBC) to the first SC-TD data symbol and the second SC-TD data symbol to define first STBC data and second STBC data corresponding to the first SC-TD data symbol and third STBC data and fourth STBC data corresponding to the second SC-TD data symbol, generating a first time domain signal that includes the first STBC data in a first part and the third STBC data in a second part, generating a second time domain signal that includes the fourth STBC data in the first part and the second STBC data in the second part, including the first SC-TD reference signal symbol in the first time domain signal and the second SC-TD reference signal symbol in the second time domain signal, wherein the first SC-TD reference signal symbol and the second SC-TD reference signal symbol are located in non-interfering symbols or non-interfering portions of symbols, and transmitting the first time domain signal and the second time domain signal over different antennas. Additionally, this aspect may include creating respective cyclic prefixes based on each of the respective STBC data and the SC-FD reference signal symbols in each of the first time domain signal and the second time domain signal.

As mentioned above, it should be noted that although the description herein and examples may refer to the case of two transmit antennas, it should be understood that the same technique could be applied to more than two antennas. One approach to this is by grouping the antennas into pairs and applying the technique on each pair. Another approach is to split the single DFT-s-OFDM symbol into more than two sub parts, apply the STBC encoding across the resulting sub parts, and including a TDM RS (DMRS or PTRS) for each transmit antenna, to create the transmitted signal for each transmit antenna.

In another aspect, the present disclosure provides considerations on PTRS with respect to the above-noted signal coding/decoding scheme <NUM> (or <NUM>). When using signal coding/decoding scheme <NUM> (or <NUM>) only for the single DFT-s-OFDM symbol, no separate PCRS may be required because phase noise mainly causes phase drift across multiple symbols. Thus, the above-described single symbol solution may be unaffected.

When extending signal coding/decoding scheme <NUM> (or <NUM>) for use across multiple DFT-s-OFDM symbols, however, then PCRS may be included in at least some portion of the above-described reference signal. For example, this extension of signal coding/decoding scheme <NUM> (or <NUM>) may be used for multiple symbols such as, but not limited to, long PUCCH/PUSCH with STBC.

In this case, this extension of signal coding/decoding scheme <NUM> (or <NUM>) may include splitting each of the multiple DFT-s-OFDM symbols as discussed above.

Alternatively, the DFT-s-OFDM symbols may be paired, and the above solution may be used across pairs. In this approach, splitting may be necessary only for a single unpaired symbol (if there is one).

Additionally, in an extension of signal coding/decoding scheme <NUM> (or <NUM>), the reference signal in <FIG>, that was a DMRS in the main solution, may be replaced with a PTRS, at least on a subset of the DFT-s-OFDM symbols. In this case of using PTRS, the reference signal overhead can be reduced relative to when DMRS is used as the reference signal, depending on a strength of the phase noise.

For example, one implementation of this aspect may include the procedure of signal coding/decoding scheme <NUM> (or <NUM>) either applied to split each of multiple DFT-s-OFDM symbols, or used across pairs of multiple DFT-s-OFDM symbols, wherein the reference signal includes a phase noise tracking reference signal on at least a subset of the multiple DFT-s-OFDM symbols.

Additionally, this extension of signal coding/decoding scheme <NUM> (or <NUM>) can be applied even in the absence of transmit diversity. For instance, the PTRS can be inserted within a single DFT-s-OFDM symbol, with possibly lower overhead, on at least a subset of the multiple DFT-s-OFDM symbols.

For example, referring to <FIG>, one implementation of this aspect may include a method <NUM> for transmission of a single-carrier waveform including generating a single-carrier waveform from a single transmit antenna including both a reference signal and data in multiple DFT-s-OFDM symbols, the reference signal comprises a phase noise tracking reference signal (PTRS), at block <NUM>, and transmitting, at block <NUM>, the single-carrier waveform via the single transmit antenna.

In another, non-claimed aspect, the present disclosure includes a variation of the above signal coding/decoding scheme <NUM> (or <NUM>) that may be utilized, but that breaks the single-carrier property.

For example, instead of splitting the DFT-s-OFDM symbol into two, the input to the DFT precoding for DFT-s-OFDM could be split into two smaller DFTs, whose outputs are then multiplexed into the larger IDFT.

The multiplexing may include FDM multiplexing, either contiguous in frequency, or interleaved. In some instance, interleaved multiplexing is preferable so that Alamouti encoded symbol-pairs see approximately the same channel.

Each of the smaller DFT by itself would result in a single carrier waveform, however, the FDM may break this property, making it a "multi-cluster" transmission (<NUM> clusters). This result may contribute some peak-to-average power ratio (PAPR) increase.

Additionally, this aspect may further include applying Alamouti encoding across the clusters. Further, in this aspect, a reference signal, e.g.. , DMRS or PTRS, can be inserted into each cluster.

For example, referring to <FIG>, one implementation of this aspect may include a method <NUM> for transmission of a waveform including receiving modulation symbols at block <NUM> and inputting a first portion of the modulation symbols into a first discrete Fourier transform to obtain a first symbol cluster at block <NUM>. At block <NUM>, method <NUM> may further include inputting a first second portion of the modulation symbols into a second discrete Fourier transform to obtain a second symbol cluster. Further, at block <NUM>, method <NUM> may include multiplexing the first cluster and the second cluster as inputs into an inverse discrete Fourier transform to obtain a multi-cluster vector, and, at block <NUM>, space-time block encoding each of the first cluster and the second time domain cluster. Additionally, at block <NUM>, method <NUM> may include inserting a reference signal into at least one symbol of each of the first time domain cluster and the second time domain cluster, and transmitting, at block <NUM>, the multi-cluster vector. In this implementation, time-domain is at input to DFT, the output is in frequency domain, then the big inverse DFT (into which the <NUM> clusters are multiplexed) again outputs time-domain.

In another aspect, the present disclosure may include the use of virtual antennas and precoding to map the virtual antennas to a physical antenna. <FIG> shows TDM separation of the reference signal from two transmit antennas, however, this may not be strictly necessary. For instance, the transmit antennas shown in <FIG> could be virtual antennas that are mapped to actual antennas using a precoding matrix. It should be noted that a non-diagonal precoder may break the TDM property of the reference signals at the physical antennas. In this aspect, the precoder is either absorbed into the propagation channel (e.g., the same precoder for data and reference signal, but can be unknown to receiver), or is known to the receiver (e.g., the receiver can account for it). A non-diagonal precoder may also break the single-carrier property of the waveform at the physical antennas, due to the combining of two single-carrier waveforms necessary in such a precoding.

In another non-claimed aspect, signal coding/decoding scheme <NUM> (or <NUM>) may be used for multiplexing of transmitters instead of transmit diversity. For instance, the receiver of the multiplexed transmissions could be UE <NUM> receiving and decoding transmissions simultaneously or contemporaneously from two different eNodeBs <NUM>, or a single eNodeB <NUM> receiving and decoding transmissions simultaneously or contemporaneously from two different UEs <NUM>. For example, in this aspect, TxAnt <NUM> and TxAnt <NUM> are replaced by UE1 and UE2. Further, the Alamouti code is replaced by an overlay Walsh code. For instance, instead of (a, b) from TxAnt <NUM> and (-b*,a*) from TxAnt <NUM> based on the Alamouti code in the respective time domain transmission symbol vector <NUM>, <NUM> and <NUM>, <NUM>, this aspect would have (a, a) from UE1 and (b,-b) from UE2 based on an overlay Walsh code.

For example, referring to <FIG>, one implementation of this aspect may include a method <NUM> of wireless communication including receiving a first transmission from a first transmitter having overlay Walsh code data a in a first time domain symbol and also in a second time domain symbol at block <NUM>. Also, at block <NUM>, method <NUM> may include receiving a second transmission from a second transmitter having overlay Walsh code data b in the first time domain symbol and overlay Walsh code -b in the second time domain symbol. Additionally, at block <NUM>, method <NUM> may include combining the symbols to decode the first transmission from the first transmitter and the second transmission from the second transmitter.

Referring to <FIG>, one example of an implementation of UE <NUM> may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM> and memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and signal processing component <NUM> and signal coding/decoding scheme <NUM> (and its modifications, described above) to enable one or more of the functions described herein. Further, the one or more processors <NUM>, modem <NUM>, memory <NUM>, transceiver <NUM>, RF front end <NUM> and one or more antennas <NUM>, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies.

In an aspect, the one or more processors <NUM> can include a modem <NUM> that uses one or more modem processors. The various functions related to signal processing component <NUM> and signal coding/decoding scheme <NUM> may be included in modem <NUM> and/or processors <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver <NUM>. In other aspects, some of the features of the one or more processors <NUM> and/or modem <NUM> associated with signal processing component <NUM> and signal coding/decoding scheme <NUM> may be performed by transceiver <NUM>.

Also, memory <NUM> may be configured to store data used herein and/or local versions of applications <NUM> or signal processing component <NUM> and/or one or more of its subcomponents being executed by at least one processor <NUM>. Memory <NUM> can include any type of computer-readable medium usable by a computer or at least one processor <NUM>, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory <NUM> may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining signal processing component <NUM> and/or one or more of its subcomponents, and/or data associated therewith, when UE <NUM> is operating at least one processor <NUM> to execute signal processing component <NUM> and/or one or more of its subcomponents.

Receiver <NUM> may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). Additionally, receiver <NUM> may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. Transmitter <NUM> may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium).

Referring to <FIG>, one example of an implementation of base station <NUM> may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM> and memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and signal processing component <NUM> and signal coding/decoding scheme <NUM> to enable one or more of the functions described herein.

Claim 1:
A method (<NUM>) of transmission in wireless communications, comprising:
generating (<NUM>) a single-carrier waveform for transmitting data and a reference signal, wherein the generating includes:
generating at least one discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, data symbol for the data, and a DFT-s-OFDM reference signal symbol for the reference signal;
splitting the at least one DFT-s-OFDM data symbol into a first single carrier time domain, SC-TD, data symbol and a second SC-TD data symbol;
splitting the DFT-s-OFDM reference signal symbol into a first SC-TD reference signal symbol and a second SC-TD reference signal symbol;
encoding, based on a space-time block code, STBC, the first SC-TD data symbol to define first STBC data and second STBC data, which collectively correspond to the first SC-TD data symbol;
encoding, based on the STBC, the second SC-TD data symbol to define third STBC data and fourth STBC data, which collectively correspond to the second SC-TD data symbol;
generating a first time domain signal vector configured to include the first STBC data and the third STBC data;
generating a second time domain signal vector configured to include the fourth STBC data and the second STBC data; and
inserting the first SC-TD reference signal symbol and the second SC-TD reference signal symbol respectively in the first time domain signal vector and the second time domain signal vector, wherein the first SC-TD reference signal symbol and the second SC-TD reference signal symbol are arranged in non-interfering symbols or non-interfering portions of symbols; and
transmitting (<NUM>), as the single-carrier waveform, the first time domain signal vector and the second time domain signal vector respectively from at least first and second antennas,
wherein inserting the first SC-TD reference signal symbol and the second SC-TD reference signal symbol respectively in the first time domain signal vector and the second time domain signal vector includes either one of:
including the first SC-TD reference signal symbol only with the first STBC data and the second SC-TD reference signal symbol with only the second STBC data; or
including the first SC-TD reference signal symbol with both the first STBC data and the third STBC data, and the second SC-TD reference signal symbol with both the fourth STBC data and the second STBC data, using a time division multiplexing, TDM, time allocation.