Re muting for DFT-s-OFDM with ptrs

Abstract

A method, network node and user equipment (UE) for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS) are disclosed. According to one aspect, a method in a network node includes, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining locations of a plurality of phase tracking reference signals, PTRS, within a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

Description

[0001] RE MUTING FOR DFT-s-OFDM WITH PTRS

[0002] FIELD

[0003] The present disclosure relates to wireless communications, and in particular, to resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS).

[0004] BACKGROUND

[0005] The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile user equipments (UE), as well as communication between network nodes and between UEs. The 3GPP is also developing standards for Sixth Generation (6G) wireless communication networks.

[0006] 3GPP NR Standard

[0007] 3GPP New radio (NR) is being designed to provide service for multiple use cases such as enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), and machine type communication (MTC). Each of these services has different technical requirements. For example, the general requirement for eMBB is high data rate with moderate latency and moderate coverage, while URLLC service requires a low latency and high reliability transmission but perhaps for moderate data rates.

[0008] An NR slot consists of several orthogonal frequency division multiplexed (OFDM) symbols, according to current agreements either 7 or 14 symbol (for OFDM subcarrier spacing < 60 kHz) and 14 symbols (for OFDM subcarrier spacing > 60 kHz). The example of FIG. 1 shows a slot with 14 OFDM symbols. In FIG. 1, Tsand Tsymbdenote the slot and OFDM symbol duration, respectively.

[0009] Different types of duplex communication modes

[0010] To support the many types of targeted use cases with varying requirements, different duplex communication modes are considered in 3GPP standardization.

[0011] Moreover, the same device may be capable of operating using different duplex modes, for, e.g., to achieve different overall communication performance based on its needs.Transmission and reception from a wireless communication device, e.g., a basestation (BS, e.g., network node) or a user equipment (UE) in a cellular system, may be multiplexed in the frequency domain or in the time domain (or combinations thereof). Some duplex modes are considered below.

[0012] Definitions of different duplex modes

[0013] • Frequency Division Duplex (FDD), as illustrated in the example of FIG.

[0014] 2, implies that transmission (TX) and reception (RX) take place in different, sufficiently separated carriers. Thus, FDD requires a paired spectrum. In case of FDD operation, there are two carrier frequencies, one for uplink (UE) transmission and one for downlink (DE) transmission. At least with respect to the UE in a cellular communication system, FDD may be either full duplex (FD-FDD) or half duplex (HD-FDD). In the FD-FDD case, a UE may transmit and receive simultaneously, while in HD-FDD operation, the UE cannot transmit and receive simultaneously (the network node is still capable of simultaneous RX / TX though, e.g., receiving from one UE while simultaneously transmitting to another UE). In LTE, a HD-FDD terminal is monitors and receives in the DL except when explicitly being instructed to transmit in a certain subframe.

[0015] • Time Division Duplex (TDD), as illustrated in the example of FIG. 3, implies that TX and RX take place within the same carrier in different, non-overlapping time slots. Thus, TDD may operate in an unpaired spectrum. In case of TDD operation, there is only a single carrier frequency and UL and DL transmissions are always separated in time and also on a cell basis. As the same carrier frequency is used for UL and DL transmission, both the network node and the UEs switch from TX to RX and vice versa. An aspect of a TDD system is to provide the possibility for a sufficiently large guard time where neither DL nor UL transmissions occur. This is done to avoid interference between UL and DL transmissions. For NR, this guard time is provided by special slots, which are split into three parts: symbols for DL, a guard period (GP), and symbols for UL. The remaining slots are either allocated to UL or DL transmission.

[0016] • Sub-Band Full Duplex (SBFD), as illustrated in the example of FIG. 4, is being studied in 3GPP Technical Release 18 (3GPP Rel-18) as a part of the 5G- Advanced standardization. In case of SBFD operation, a portion of a wide bandwidth carrier, termed sub-band(s), may be used for a different communication direction than that of the rest of the carrier. This is unlike the conventional TDD operation wherein the entire bandwidth of the carrier is always used either for DL or UL. SBFD operation may also be performed across different carriers within the same frequency band, wherein one or more carrierswithin a frequency band may be used for a different communication direction than that of the other carriers. This is also unlike conventional TDD operation wherein all carriers within a frequency band are always used for the same communication direction. In the 3GPP Rel-18 study, the scope has been limited such that during SBFD operation, only network nodes transmit DL and receive UL simultaneously using corresponding nonoverlapping sub-bands. An individual UE is scheduled in only one direction (DL or UL) at a time, following conventional HD TDD operation, referred to as HD-SBFD. However, for future releases such as 3GPP Rel-19, SBFD operation at UEs is also being considered as a potential study topic, referred to as SBFD.

[0017] • Single frequency full duplex (SFFD), as illustrated in FIG. 5, has also been considered to be studied in 3GPP standardization. It was considered but excluded from the scope of 3GPP Rel-18, and it is now again being considered during scoping for 3GPP Rel-19. In case of SFFD operation, the entire bandwidth of the same carrier in a single carrier system or all carriers in a multi-carrier system may be simultaneously used for DL and UL operations. In other words, the same time and frequency resources may be used for both TX and RX at the same device. Similar to SBFD operation, SFFD operation is also being considered as a potential study topic for both network nodes and UEs.

[0018] SBFD self-interference

[0019] Since the network node transmits on the DL while at the same time receiving on the UL, there is the risk of strong self-interference. In an ideal situation with no RF / analog imperfections in transmitter or receiver, the fact that DL and UL are transmitted on different subbands, combined with the orthogonality between OFDM subcarriers, will effectively lead to no self-interference between TX and RX (at least if OFDM subcarrier grids in TX and RX side are assumed to be perfectly aligned.) However, in real equipment with imperfections, there will be self-interference through two mechanisms:

[0020] 1. The TX signal is distorted due to transmitter-side imperfections, in particular non-linearities in the power amplifier (PA). This will lead to power being transmitted also in the uplink (UL) subband, and hence cause interference to the desired UL signal; and

[0021] 2. The receiver analog components, e.g., the low-noise amplifier (LNA), have non-linearities. This causes the receiver to capture power from the downlink (DL) subband.

[0022] These two effects are illustrated in the examples of FIGS. 6 and 7.Cubic metric (CM) and peak-to-average power ratio (PAPR)

[0023] In a practical implementation, the transmitted signal may become heavily distorted if its peak power becomes larger than the power amplifier may handle. For maximum power efficiency, one should therefore strive to have a transmitted signal with as little variation of power around its average power as possible. Two measures of such variations are peak-to-average power ratio (PAPR) and cubic metric (CM):

[0024] The peak-to-average power of a signal s(t) in continuous time t is defined as max |s(t)|2(8) PAPR [dB] = 10log10*

[0025]

[0026] -Jo|s(t)|2dt where T is the duration of the signal.

[0027] In some cases, especially for UL transmission, CM is usually considered a more appropriate measure than PAPR. The CM accounts not only for the maximum peak of the signal, but also for the number of large peaks. The CM is may be calculated as: where the signal s(t) is assumed to be normalized, i.e.,

[0028] CM [dB] = 10log10[T∫₀ᵀ|s(t)|⁶dt]-1.52 (9) / 1.56

[0029]

[0030] = i. <10)However, there are other possible choices of the constants 1.52 and 1.56. There are also other possible measures of variation than PAPR and CM. The methods and technical benefits disclosed herein are generally applicable without regard to the variation measure that is used.

[0031] DFT-s-OFDM and CP-OFDM

[0032] A primary target for SBFD is increased coverage, which is achieved through longer UE transmission time (up to 5 slots per 5-slot group instead of just 1 as in legacy time division duplex (TDD) pattern DDDDU).

[0033] In coverage-limited situations, it may be desirable to maximize the TX power that the UE may use. Maximum TX power is achieved if discrete Fourier transform (DFT)-spread OFDM (DFT-s-OFDM) rather than non-DFT-spread OFDM (henceforth referred to a cyclic prefix (CP)-OFDM for brevity) is used, the reason being that DFT-s-OFDM has lower cubic metric (CM) than CP-OFDM, and therefore a higher average transmission power is possible without experiencing significant distortion in the UE power amplifier (PA).

[0034] The principle of CP-OFDM is illustrated in the example of FIG. 8 and the principle of DFT-s-OFDM is shown in the example of FIG. 9. The difference between DFT-s-OFDM and CP-OFDM is that DFT-s-OFDM has a DFT for converting modulated symbols (e.g., quadrature amplitude modulation (QAM) symbols) to the frequency domain before mapping to subcarriers, while in CP-OFDM, modulated symbols are directly mapped to subcarriers in the frequency domain.

[0035] The typical generation of frequency-domain resource elements (REs) (subcarriers) in a legacy system without muting is that first a discrete Fourier transform (DFT) is taken of M modulated symbols s, forming s = DFT(s), which are then mapped to subcarriers in consecutive order, possibly after first performing a “DFT shift”. The term “DFT shift” refers here to exchanging the first and second halves of s, i.e., for a length-M DFT:

[0036] SDFT-shifted(m) = sbefore-DFT-shift(M / 2 + m), for m = 0,1,... M / 2 - 1 SDFT-shifted(M / 2 + m) = Sbefore-DFT-Shift(m), for m = 0,1,... M / 2 - 1 Furthermore, similar to DFT shift, there may be an “IDFT shift” before or after the inverse DFT (IDFT) operation. For even-length, an IDFT shift is mathematically equivalent to a DFT shift.

[0037] A DFT-shift (or IDFT shift) may sometimes be seen as an integral part of the DFT (IDFT) operation, and is then not explicitly indicated.

[0038] NR phase tracking reference symbols (PTRS)

[0039] The phase tracking reference symbols (PTRS) are defined in the NR specifications to enable the receivers to estimate effects of phase noises. These reference symbols are particularly useful for NR carriers in higher frequency ranges (such as the FR2). The PTRS are defined for both downlink and uplink transmissions in NR.

[0040] For a physical downlink shared channel (PDSCH) or physical uplink shared channel (PUSCH), the accompanying PTRS are confined to the scheduled bandwidth in the frequency domain and the scheduled OFDM symbols in the time domain. For a PDSCH or PUSCH with a CP-OFDM waveform, different frequency domain density and time domain density are supported:

[0041] • The time domain density may be one of LPT-RS= 1, 2 or 4. These densities correspond to one PTRS presence every OFDM symbol, every two OFDM symbols, or every four OFDM symbols; and

[0042] • The frequency domain density may be one of KPT-RS= 2 or 4. These densities correspond to one PTRS subcarrier every two resource blocks (RBs) or every four RBs.

[0043] For example, FIG. 10 shows an example PTRS configuration of time domain density of LPT-RS= 1 and frequency domain density of KPT-RS= 2. FIG. 11 shows anexample of time domain density of LPT-RS= 2 and frequency domain density of KPT-RS= 4. It is noted that the legend in FIG. 11 also applies to FIG. 10.

[0044] In the current NR specifications, the time domain density is determined in two steps:

[0045] • First the network may provide radio resource control (RRC) configuration of a set of three threshold MCS (modulation and coding scheme): ptrs-MCSl, ptrs-MCS2 and ptrs-MCS3. If the configuration is not provided by the network, specific threshold values are listed in the NR 3GPP Technical Standard (TS) 38.213; and

[0046] • The actual time domain density accompanying a PDSCH or a PUSCH is determined by comparing the MCS for the schedule PDSCH or a PUSCH, which is denoted by IMCS, to the three MCS thresholds as shown in Table 1.

[0047] Table 1 Time density of PT-RS as a function of scheduled MCS Time density Scheduled MCS

[0048] (LpT-Rs)

[0049] IMCS < ptrs-MCS1 PT-RS is not present ptrs-MCS 1 < IMCS < ptrs- 4

[0050] MCS2

[0051] ptrs-MCS2 < IMCS < ptrs- 2

[0052] MCS3

[0053] ptrs-MCS3 < IMCS < ptrs- 1

[0054] MCS4

[0055]

[0056] In the current NR specifications, the frequency domain density is determined in two steps:

[0057] • First the network may provide RRC configuration of a set of two threshold RB sizes: NRBO and NRBI. If the configuration is not provided by the network, specific threshold values are listed in the 3GPP TS 38.213; and

[0058] • The actual frequency domain density accompanying a PDSCH or a PUSCH is determined by comparing the allocated number of RBs for the schedule PDSCH or a PUSCH, which is denoted by NRB, to the two RB size thresholds as shown in Table 2.Table 2 Frequency density of PT-RS as a function of scheduled bandwidth Scheduled Frequency density bandwidth (K PT-RS)

[0059] NRB < NRBO PT-RS is not present

[0060] NRBO - NRB < NRBI 2

[0061] NRBI - NRB 4

[0062]

[0063] For a PUSCH with DFT-S-OFDM waveform, the PTRS are inserted in the time domain amongst the modulated symbols of the PUSCH data. This is illustrated in FIG. 12.

[0064] The time density of a PT-RS for a DFT-s-OFDM waveform is either LPT-RS= 2 if the network provides such time density configuration, or LPT-RS= 1 if the network does not provide a configuration of time density.

[0065] In the current 3GPP specifications, the sample density of the PT-RS for a DFT-s-OFDM waveform within an OFDM symbol is a function of the number of PT-RS groups and the number of samples per group. The sample density is determined in two steps:

[0066] • First the network provides RRC configuration of a set of five threshold RB sizes: NRBi, where i=0, 1,..., 5; and

[0067] • The actual sample density accompanying the PUSCH with DFT-S-OFDM waveform is determined by comparing the allocated number of RBs for the schedule PUSCH, which is denoted by NRB, to the five RB size thresholds as shown in Table 3. This determines the number of PT-RS groups and number of samples per group.

[0068] Table 3 Sample density of PT-RS for PUSCH with DFT-S-OFDM waveform within an OFDM symbol as a function of scheduled bandwidth

[0069] Scheduled Number of PT-RS groups Number of samples per group bandwidth IUFT-RS ly group

[0070] 1* groupvsample

[0071] NRBO -NRB < NRBI 2 2

[0072] NRBI - NRB < NRB2 2 4

[0073] NRB2 - NRB < NRB3 4 2

[0074] NRB3 ≤ NRB < NRB4 4 4

[0075] NRB4 - NRB 8 4

[0076]

[0077] When a PTRS is configured for a PDSCH or a PUSCH, the PTRS is associated with the demodulation reference signal (DMRS) port of the scheduled PDSCH or PUSCH.In the current 3GPP specifications, at most two PTRS ports may be configured for PDSCH or PUSCH with an CP-OFDM waveform.

[0078] The current higher layer configuration for downlink PTRS is shown below:

[0079] - ASN1 START

[0080] PTRS-DownlinkConfig::= SEQUENCE {

[0081] frequencyDensity SEQUENCE (SIZE (2)) OF INTEGER ( 1..276) OPTIONAL, - NeedS

[0082] timeDensity SEQUENCE (SIZE (3)) OF INTEGER (0..29) OPTIONAL, - NeedS

[0083] epre-Ratio INTEGER (0..3) OPTIONAL, - Need S

[0084] resourceElementOffset ENUMERATED { offsetOl, offset 10, offset 11 } OPTIONAL, - NeedS

[0085] [[

[0086] maxNrofPorts-rl6 ENUMERATED {nl, n2}

[0087] OPTIONAL - Need R

[0088] ]]

[0089] }

[0090] - ASN1STOP

[0091] The current higher layer configuration for uplink PTRS is shown below for both CP-OFDM (transformPrecoderDisabled) and DFT-s-OFDM (transformPrecoderEnabled):

[0092] - ASN1 START

[0093] PTRS-UplinkConfig::= SEQUENCE { transformPrecoderDisabled SEQUENCE {

[0094] frequencyDensity SEQUENCE (SIZE (2)) OF INTEGER (1..276) OPTIONAL, - NeedS

[0095] timeDensity SEQUENCE (SIZE (3)) OF INTEGER (0..29) OPTIONAL, - NeedS

[0096] maxNrofPorts ENUMERATED { n 1, n2 }, resourceElementOffset ENUMERATED {offsetOl, offsetlO, offsetll } OPTIONAL, - NeedS

[0097] ptrs-Power ENUMERATED {p00, pOl, plO, pl 1 }

[0098] } OPTIONAL, - NeedRtransformPrecoderEnabled SEQUENCE {

[0099] sampleDensity SEQUENCE (SIZE (5)) OF INTEGER (1..276), timeDensityTransformPrecoding ENUMERATED { d2 } OPTIONAL - Need S

[0100] } OPTIONAL, - Need R

[0101] • • • 9

[0102] [[

[0103] maxNrofPorts-SDM-rl8 ENUMERATED {nl, n2}

[0104] OPTIONAL - Need R

[0105] ]]

[0106] }

[0107] - ASN1STOP

[0108] NR PTRS generation and placement for PUSCH with DFT-S-OFDM waveform For an OFDM symbol carrying PTRS in PUSCH with an DFT-S-OFDM waveform, five different sample densities for the PTRS are defined in NR. The corresponding placement patterns for these five sample densities based on the configured number of groups, denoted by Ngroups. and the number of samples per group, denoted by ^sampP’as wc"asthe available number of REs denoted by MscPUSCHare provided in 3GPP TS 38.211, which is reproduced in Table 4.

[0109] The PTRS rm(m'') to be mapped in position m before transform precoding (given in Table 4) is computed as:

[0110] jm mod 2

[0111] r̃(m') = w(k') · jm mod 2· [(1 - 2c(m')) + j(1 - 2c(m'))]

[0112] m' = Nl^s' + k'

[0113] S' = 0,1. iVj’roup3- 1

[0114]

[0115] £' = 0,1. Nsampp- 1

[0116] where c(m') is a pseudo random sequence described in the and w( / c') is an orthogonal spreading sequence of length Nsampp- The value of the w( / c') is determined by Nsamppand the radio network temporary identification (RNTI), denoted by nRNTI, as defined in 3GPP TS 38.211, which is reproduced in Table 5.Table 4 PTRS placement indices for an OFDM symbol carrying PTRS in PUSCH with DFT-S-OFDM waveform corresponding to the five sample densities in NR.

[0117] Number Number Index m of PT-RS samples in OFDM symbol I prior to of of transform precoding

[0118] PT-RS samples

[0119] groups per PT / W gPrTo-uRpS RS

[0120] group

[0121] yygroup

[0122] 1 vsamp

[0123] 2 2 S[MPUSCH / 4] + k — 1 where s = 1,3 and k = 0,1

[0124] 2 4 sMscPUSCH / 8 + k - 1 where s = 0, and k = 0, 1, 2, 3,

[0125] sc(s = 1 and k = — 4, — 3, — 2, — 1

[0126] 4 2 |s MPUSCH / 8] + k — 1 where s = 1,3, 5, 7 and k = 0,1 4 4 sMscPUSCH / 4 + n + k where

[0127] fs = 0 and k = 0, 1,2,3 n = 0

[0128] | s = 1,2 and k = -2, -1,0,1 n = [MPUSCH / 8] (s = 4 and k = — 4, — 3, — 2, — 1 n = 0

[0129] 8 4 |s MPUSCH / 8] + n + k where

[0130] fs = 0 and k = 0,1, 2, 3 n = 0

[0131] J s = 1,2, 3, 4, 5, 6 and k = -2, -1,0,1 n = [MPUSCH / 16 (s = 8 and k = — 4, — 3, — 2, — 1 n = 0

[0132]

[0133] Table 5 The orthogonal spreading sequence for PTRS in PUSCH with DFT-S-OFDM waveform.

[0134] nRNTi mod IVf™uppyygroup _ 2 ^group= 4

[0135] 1 vsamp ’ samp

[0136] [w(0)W(l)] [w(0) w(l) w(2) w(3)]

[0137] 0 [+1+1] [+1 +1 +1 +1]

[0138] 1 [+1 -1] [+1 -1 +1 -1]

[0139] 2 - [+1 +1 -1 -1]

[0140] 3 - [+1 -1 -1 +1]

[0141]

[0142] RE muting (consideration for standardization in 3GPP)

[0143] It has been considered in 3GPP Technical Report (TR) 38.858 that some resource elements of an OFDM symbol in UL transmissions may be muted in order to allow the network node to more accurately estimate DL interference (by measuring it on the muted RE where it is not influenced by UL signals). Muting may be either a (or multiple) full OFDM symbols or a subset of the subcarriers, e.g., every Nth subcarrier, as illustrated in FIG. 13. Data is supposed to be rate-matched around the muted RE, i.e., muting in principle does not change the code rate, but does reduce the number of transmitted bits and hence, decreases throughput.

[0144] Lower Layer Split (LLS) Architecture in O-RAN WG4

[0145] A typical network node implementation is based on a split architecture, where some aspects of PHY layer processing are located within a distributed unit (DU) and other aspects are located within a radio unit (RU) where the DU and RU communicated over a fronthaul interface as illustrated in the example of FIG. 14. This split architecture is referred to as lower layer split (LLS).

[0146] In O-RAN standards, the DU is referred to as O-DU, the RU as O-RU. Working Group 4 (WG4) in O-RAN generates specifications for the fronthaul interface.

[0147] The benefits of massive multiple input-multiple output (MIMO) introduce challenges at the base-station with regards to signaling over the fronthaul interface. The legacy common public radio interface (CPRI)-type fronthaul transports time-domain IQ samples per antenna branch. As the number of antennas scales up in massive MIMO systems, the required fronthaul capacity also increases proportionally, which significantly drives up the fronthaul costs. To help address this challenge, the fronthaul interface has evolved from CPRI to enhanced CPRI (eCPRI) which is a packet-basedfronthaul interface. O-RAN WG4 specifications are based on eCPRI. With eCPRI, the frequency-domain beamforming function is moved from DU to RU so that frequency samples of beamformed streams (UL) or user-data layers (DL) are transported over the fronthaul interface instead of time domain samples per-antenna as in CPRI. This helps reduce required fronthaul bitrates since the number of beamformed streams / user-data layers is typically much smaller than the number of antennas in massive MIMO.

[0148] Control, User, and Synchronization (CUS) Plane Specifications in O-RAN WG4 Signaling over the fronthaul interface between O-DU and O-RU is specified in the following WG4 specifications: O-RAN ALLIANCE “O-RAN Control, User and Synchronization Plane Specification 16.0", 0-RAN. WG4. CUS.0-R004-vl6.00, July 2024; O-RAN ALLIANCE “O-RAN Management Plane Specification 16.0", O-RAN. WG4. MP.0-R004-vl6.00, July 2024; O-RAN ALLIANCE “O-RAN Management Plane Specification - YANG Models 16.0", O-RAN. WG4. MP-YANGs-R004-vl 6.00, July 2024. These specifications include the following types of signaling:

[0149] • Control plane (C-Plane) signaling:

[0150] ■ For controlling the O-RU and providing RRM measurement reports;

[0151] • User plane (U-Plane) signaling:

[0152] ■ For carrying frequency domain I-Q sample data between O-DU and O-RU for both DL and UL;

[0153] • Synchronization plane (S-Plane) signaling:

[0154] ■ For synchronizing O-DU and O-RU; and

[0155] • Management plane (M-Plane) signaling:

[0156] ■ For reporting O-RU capabilities to the O-DU, e.g., at start-up; and ■ For providing configuration commands to the O-RU based on reported capabilities, e.g., at start-up.

[0157] For each slot, the O-DU first sends C-plane message(s) to convey scheduling information to the O-RU. The scheduling information includes the resource elements (REs) and the OFDM symbols within the slot to be scheduled, e.g., for PUSCH, for all scheduled UEs. The O-RU receives the scheduling information and then processes the scheduled RBs according to the scheduling information received. Then the O-RU sends the processed REs (i.e., U-plane data) in U-plane messages to the O-DU.

[0158] Control-Plane Signaling

[0159] The scheduling information is contained in a C-plane message, for example, using the so-called Section Type 5 (ST5) format. The ST5 format is shown in Table7.4.7- 1 of O-RAN ALLIANCE “O-RAN Control, User and Synchronization Plane Specification 16.0", 0-RAN. WG4. CUS.0-R004-vl6.00, July 2024, reproduced in FIG. 15. The different color shadings used in this table indicate different “sections” of the slot, where a section corresponds to a certain physical resource block (PRB) range and OFDM symbol range which is allocated to PUSCH for one or more users. In other words, a section corresponds to a certain rectangle in the time / frequency grid. For the case of contiguous RB allocation, the PRB range of the section is indicated using fields for the starting PRB (startPrbc) and number of PRBs (numPrbc). The OFDM symbol range is indicated using fields for the starting symbol within a slot (startSymbolId) in the message header and number of symbols (numSymbol) and / or symbol increment (symlnc). The field reMask may be used to indicate the specific REs within all RBs and all OFDM symbols of the section for which the C-plane message applies.

[0160] If the flag “ef” in a section description is set to ‘1’, then one or more Section Extensions may be appended to the section description (e.g., see Octets 25 and N+8 in FIG. 15). Section Extensions carry additional information that applies to the section.

[0161] Management Plane Signaling

[0162] In O-RAN, the O-RU reports its capability at start up so that the O-DU may obtain information about what functionality the O-RU supports, what capacity it has, and what limitations it has. This capability reporting is performed over the management plane (M-plane), which uses Network Configuration Protocol (NETCONF). Based on the reported capabilities, the O-DU may manage the O-RU by sending configuration commands to the O-RU also over M-Plane based on these capabilities. For example, the O-DU may configure a DL carrier (tx-array-carrier) and an UL carrier (rx- array-carrier) and activate them such that C-plane and U-Plane messages may be sent over the fronthaul interface on C-Plane and U-plane, respectively. The O-RAN M-plane specifications are contained in: O-RAN ALLIANCE “O-RAN Management Plane Specification 16.0", O-RAN. WG4. MP.0-R004-vl6.00, July 2024; and O-RAN ALLIANCE “O-RAN Management Plane Specification - YANG Models 16.0", O-RAN. WG4. MP-YANGs-R004-vl6.00, July 2024. The M-plane specifications use the YANG (Yet Another Next Generation) modeling language. This modular language is used to represent data structures in an extended markup language (XML) tree format for signaling configuration parameters to the O-RU.

[0163] As explained above, it may be helpful to use DFT-s-OFDM in scenarios where SBFD is used. For frequency range 2, it may be helpful to be able to track and compensatefor phase noises by configuring PTRS to be present in every PUSCH OFDM symbol. There is currently no solution as to how to combine RE muting and PTRS transmission for DFT-s-OFDM with low cubic metrics.

[0164] SUMMARY

[0165] Some embodiments advantageously provide methods, network nodes and user equipments (UEs) for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS).

[0166] Methods of PTRS generation and placement to support RE muting for DFT-s-OFDM transmissions are disclosed. Principles disclosed herein are applicable not only to SBFD, but also to dynamic TDD. The SBFD considerations are for simplicity focused on the case with an UE subband between two DE subbands, but the disclosed methods are equally applicable to other SBFD arrangements. Some embodiments regarding ratematching around muted REs are disclosed.

[0167] According to one aspect, a method in a user equipment, UE, configured to communicate with a network node is provided. The method includes, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

[0168] According to this aspect, in some embodiments, the number of available nonmuted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domainlocations of PTRS uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node is a core network node in a core network. In some embodiments, the method includes transmitting the uplink transmission comprising the PTRS in the determined time domain locations.

[0169] According to another aspect, a user equipment, UE, configured to communicate with a network node is provided. The UE includes processing circuitry configured to, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available nonmuted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

[0170] According to this aspect, in some embodiments, the number of available nonmuted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domain locations uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node is a core network node in a core network. In some embodiments, the processing circuitry is configured to cause transmission of the uplink transmission comprising the PTRS in the determined time domain locations.

[0171] According to yet another aspect, a method in a network node configured to communicate with a user equipment, UE, is provided. The method includes, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-mutedresource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

[0172] According to this aspect, in some embodiments, the number of available nonmuted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domain locations uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node is a core network node in a core network. In some embodiments, the method includes receiving the uplink transmission and obtaining the plurality of PTRS from the determined time domain locations in the uplink transmission.

[0173] According to another aspect, a network node configured to communicate with a user equipment, UE, is provided. The network node includes processing circuitry configured to, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a number of available nonmuted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

[0174] According to this aspect, in some embodiments, the number of available nonmuted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS withindices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domain locations uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node is a core network node in a core network. In some embodiments, the processing circuitry is configured to receive the uplink transmission and obtain the plurality of PTRS from the determined time domain locations in the uplink transmission.

[0175] BRIEF DESCRIPTION OF THE DRAWINGS

[0176] A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

[0177] FIG. 1 is an example of an NR slot;

[0178] FIG. 2 is an example of FDD;

[0179] FIG. 3 is an example of TDD;

[0180] FIG. 4 is an example of SBFD;

[0181] FIG. 5 is an example of SFFD;

[0182] FIG. 6 is an example of network node self-interference;

[0183] FIG. 7 is an example of DE TX power distribution;

[0184] FIG. 8 is an example of OFDM waveform generation;

[0185] FIG. 9 is an example of DFT-S-OFDM waveform generation;

[0186] FIG. 10 is an example of a PTRS configuration of a first time density;

[0187] FIG. 11 is an example of a PTRS configuration for a second time density;

[0188] FIG. 12 is an example of a PTRS structure for a PUSCH with a DFT-s-OFDM waveform;

[0189] FIG. 13 is an example of muting of resource elements;

[0190] FIG. 14 is an example of a fronthaul interface between an RU and a DU;

[0191] FIG. 15 a table of an example UE scheduling information frame format;FIG. 16 is a schematic diagram of an example network architecture illustrating a communication system according to principles disclosed herein;

[0192] FIG. 17 is a block diagram of a network node in communication with a user equipment over a wireless connection according to some embodiments of the present disclosure;

[0193] FIG. 18 is a schematic diagram of another example network architecture illustrating a communication system according to principles disclosed herein;

[0194] FIG. 19 is a flowchart of an example process in a network node for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS) according to some embodiments of the present disclosure;

[0195] FIG. 20 is a flowchart of an example process in a user equipment for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS) according to some embodiments of the present disclosure;

[0196] FIG. 21 is a flowchart of another example process in a network node for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS) according to some embodiments of the present disclosure;

[0197] FIG. 22 is a flowchart of another example process in a user equipment for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS) according to some embodiments of the present disclosure; and

[0198] FIG. 23 is a block diagram of an example virtualization environment.

[0199] DETAILED DESCRIPTION

[0200] Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS). Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure withdetails that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0201] As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0202] In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

[0203] In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and / or wireless connections.

[0204] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0205] The term “network node” used herein may be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio networkcontroller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multistandard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a user equipment (UE) such as a wireless device (WD) or a radio network node.

[0206] In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The UE herein may be any type of user equipment capable of communicating with a network node or another UE over radio signals, such as a wireless device (WD). The UE may also be a radio communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), low-cost and / or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device etc.

[0207] Also, in some embodiments the generic term “radio network node” is used. It may be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell / multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

[0208] Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and / or New Radio (NR) and / or 6G, may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. It is contemplated that other 3GPP systems may make use of the concepts and arrangements disclosed herein. For example, a disclosure relating to NR may also be implementable in a 6G system and / or an LTE system, a disclosure relating to 6G may also be implementable in a NR and / or LTE system, and a disclosure relating to LTE may also be implementable in a NR and / or 6G system. Other wireless systems, including withoutlimitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

[0209] Note further, that functions described herein as being performed by a user equipment or a network node may be distributed over a plurality of user equipments and / or network nodes. In other words, it is contemplated that the functions of the network node and user equipment described herein are not limited to performance by a single physical device and, in fact, may be distributed among several physical devices.

[0210] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0211] Some embodiments are directed to resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS).

[0212] Returning to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 16 a schematic diagram of a communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as UTE and / or NR (5G) and / or 6G, which comprises an access network 12, such as a radio access network, and a core network 14. The core network 14 includes one or more network nodes 15. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first user equipment (UE) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second UE 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of UEs 22a, 22b (collectively referred to as user equipments 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to thecorresponding network node 16. Note that although only two UEs 22 and three network nodes 16 are shown for convenience, the communication system may include many more UEs 22 and network nodes 16.

[0213] As one example, in certain embodiments, access network 12 may contain some access network nodes 16 that support 3GPP radio access technologies (RAT), such as LTE or NR, while other access network nodes 16 support (or the same access network nodes 16 additionally support) non-3GPP RATs, such as Wi-Fi or a proprietary RAT. As another example, communication system 10 may support multiple generations of related communication standards (e.g., 4G, 5G and 6G 3GPP communication standards) and, as a result, may include an access network 12 and / or a core network 14 that supports multiple different standard generations or may include multiple access networks 12 and / or multiple core networks 14 with individual networks supporting different standards generations.

[0214] Also, it is contemplated that a UE 22 may be in simultaneous communication and / or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a UE 22 may have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, UE 22 may be in communication with an eNB for LTE / E-UTRAN, a gNB for NR / NG-RAN (i.e. being configured for multiradio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC) and / or Wi-Fi.

[0215] A network node 16 (eNB or gNB) or core network node 15 is configured to include a network node (NN) PTRS unit 24 which may be configured to, for a DFT-s-OFDM symbol with muting, determining locations of a plurality of PTRS within a limit of ^PUSCH / 2, / V / (’1, S( H / 2 being a number of available REs with muting, M^USCHbeing a number of available REs without muting. A user equipment 22 may be configured to include a UE PTRS unit 26 which is configured to, for a DFT-s-OFDM symbol with muting, determining locations of a plurality of PTRS within a limit of M^USCH / 2, M^USCH / 2 being a number of available REs with muting, M^USCHbeing a number of available REs without muting.

[0216] Example implementations, in accordance with an embodiment, of the UE 22 and network node 16 and core network node 15 discussed in the preceding paragraphs will now be described with reference to FIG. 16.

[0217] The communication system 10 includes a network node 16 provided in a communication system 10 and including hardware 28 enabling it to communicate with theUE 22. The hardware 28 may include a communication interface 29 comprising a radio interface 30 for setting up and maintaining at least a wireless connection 32 with a UE 22 located in a coverage area 18 served by the network node 16. The radio interface 30 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 30 includes an array of antennas 34 to radiate and receive signal(s) carrying electromagnetic waves.

[0218] In the embodiment shown, the hardware 28 of the network node 16 further includes processing circuitry 36. The processing circuitry 36 may include a processor 38 and a memory 40. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 36 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 38 may be configured to access (e.g., write to and / or read from) the memory 40, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read-Only Memory).

[0219] Thus, the network node 16 further has software 42 stored internally in, for example, memory 40, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 42 may be executable by the processing circuitry 36. The processing circuitry 36 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by network node 16.

[0220] Processor 38 corresponds to one or more processors 38 for performing network node 16 functions described herein. The memory 40 is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 42 may include instructions that, when executed by the processor 38 and / or processing circuitry 36, causes the processor 38 and / or processing circuitry 36 to perform the processes described herein with respect to network node 16. For example, processing circuitry 36 of the network node 16 may include a network node (NN) PTRS unit 24 which may be configured to, for a DFT-s-OFDM symbol with muting, determining locations of a plurality of PTRS within a limit of M^USCH / 2, M^USCH / 2 being a number of available REs with muting, M^USCHbeing a number of available REs without muting.The network node 16 may be composed of multiple distinct network entities (e.g., a NodeB entity and a RNC entity, or a BTS entity and a BSC entity, etc.), which may each have or utilize their own respective physical components. In certain scenarios in which the network node 16 comprises multiple such entities (e.g., BTS and BSC), one or more of the separate entities may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 16 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories 40 or portions of memory 40 for different RATs) and some components may be reused (e.g., a same antenna may be shared by different RATs). The network node 16 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 16, for example GSM, WCDMA, LTE, NR, Wi-Fi (e.g., according to an IEEE 802.11 family standard), Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 16.

[0221] In certain alternative embodiments, network node 16 may be capable of wireless communication but does not include separate radio front-end circuitry, instead, the processing circuitry 36 includes radio front-end circuitry and is connected to the antenna 34. Similarly, in some embodiments, all or some of the RF receivers, transmitters and / or transceivers are part of the radio interface 30. In still other embodiments, the communication interface 29 includes one or more ports or terminals, the radio interface 30, and the RF receiver, transmitter and / or transceiver, and the communication interface 31 communicates with baseband processing circuitry, which is part of a digital unit (not shown).

[0222] The antenna 34 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 34 may be coupled to the radio front-end circuitry in radio interface 30 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 34 is separate from the network node 16 and connectable to the network node 16 through one or more interfaces or ports.

[0223] Network node 15 may include one or more components described above with respect to network node 16, e.g., communication interface 29, radio interface 30, antenna34, ports, processing circuitry 36, processor 38, memory 40, software 42 and NN PTRS unit 24. These elements of network node 15 may be arranged such that network node 15 may perform various core network functions. Network node 15 may communicate wirelessly or via a wired connection with network nodes 16 via communication link 59.

[0224] The communication system 10 further includes the UE 22 already referred to. The UE 22 may have hardware 44 that may include a radio interface 46 configured to set up and maintain a wireless connection 32 with a network node 16 serving a coverage area 18 in which the UE 22 is currently located. The radio interface 46 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 46 includes an array of antennas 48 to radiate and receive signal(s) carrying electromagnetic waves.

[0225] Communication functions of the radio interface 46 may include cellular communication, Wi-Fi communication (e.g., according to an IEEE 802.11 family standard), LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0226] The hardware 44 of the UE 22 further includes processing circuitry 50. The processing circuitry 50 may include a processor 52 and memory 54. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 50 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 52 may be configured to access (e.g., write to and / or read from) memory 54, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM(Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read-Only Memory).

[0227] Thus, the UE 22 may further comprise software 56, which is stored in, for example, memory 54 at the UE 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the UE 22. The software 56 may be executable by the processing circuitry 50. The software 56 may include a client application 58. The client application 58 may be operable to provide a service to a human or non-human user via the UE 22.

[0228] The processing circuitry 50 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by UE 22. The processor 52 corresponds to one or more processors 52 for performing UE 22 functions described herein. The UE 22 includes memory 54 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 56 and / or the client application 58 may include instructions that, when executed by the processor 52 and / or processing circuitry 50, causes the processor 52 and / or processing circuitry 50 to perform the processes described herein with respect to UE 22. For example, the processing circuitry 50 of the user equipment 22 may include a UE PTRS unit 26 which is configured to, for a DFT-s-OFDM symbol with muting, determining locations of a plurality of PTRS within a limit of M^USCH / 2, M^USCH / 2 being a number of available REs with muting, M^USCHbeing a number of available REs without muting.

[0229] In some embodiments, the inner workings of the network node 16 and UE 22 may be as shown in FIG. 17 and independently, the surrounding network topology may be that of FIG. 16.

[0230] The wireless connection 32 between the UE 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and / or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc. In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve.

[0231] Although FIGS. 16 and 17 show various “units” such as NN PTRS unit 24 and UE PTRS unit 26 as being within a respective processor, it is contemplated that these unitsmay be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

[0232] FIG. 18 is another example of a communication system 10 according to some embodiments. As used herein, the communication system 10 of FIG. 18 includes multiple access points (APs) 60 (with four example APs 60a, 60b, 60c, and 60d being depicted) and multiple wireless devices, referred to in the context of communication system 10 of FIG.

[0233] 18 as stations (STAs) 62 (referred to individually as STA 62a, STA 62b, STA 62c, STA 62d, and STA 62e). STA 62a is served by AP 60a in a first basic service set (BSS) 64a. STA 62b and STA 62c are served by AP 60b in a second BSS, BSS 64b. STA 62d is served by AP 60c in a third BSS, BSS 64c. STA 62e is served by AP 60d in a fourth BSS, BSS 64d. Stations 62 may be non-AP STAs and correspond to various kinds of wireless devices, for example, user terminals, such as mobile or stationary computing devices like smartphones, laptop computers, desktop computers, tablet computers, gaming devices, head-mounted displays (HMDs) for Augmented Reality (AR) or Virtual Reality (VR), or the like, including UEs 22 that are shown and described with respect to FIGS. 16 and 17. In other words, in some embodiment, STA 62 is a UE 22. Further, stations 62 may, for example, correspond to other kinds of equipment like smart home devices, printers, multimedia devices, data storage devices, or the like.

[0234] Each of STAs 62 may connect through a radio link to one of APs 60. For example, depending on location or channel conditions experienced by a given STA 62, the STA may select an appropriate AP and BSS for establishing the radio link. The radio link may be based on one or more orthogonal frequency-division multiplexing (OFDM) carriers from a frequency spectrum that is shared on the basis of a contention-based mechanism, e.g., an unlicensed or license exempt band like 2.4 GHz Industrial, Scientific, and Medical (ISM) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band.

[0235] Each AP 60 may provide data connectivity to STAs 62 connected to a particular AP 60. As illustrated, APs 60 may be connected to a data network 66. In this way, APs 60 may also provide data connectivity between STAs 62 and other entities, e.g., to one or more servers, service providers, data sources, data sinks, user terminals, or the like.

[0236] Accordingly, the radio link established between a given STA 62 and its serving AP 60 may be used for providing various kinds of services to STA 62, e.g., a voice service, a multimedia service, or other data service. Such services may be based on applications that are executed on STA 62 and / or on a device linked to STA 62. By way of example, FIG. 18illustrates an application service platform 68 provided in data network 66. The application(s) executed on STA 62 and / or on one or more other devices linked to STA 62 may use the radio link for data communication with one or more other STA 62 and / or the application service platform 68, thereby enabling utilization of the corresponding service(s) at STA 62.

[0237] FIG. 19 is a flowchart of an example process in a network node 16 or core network node 15 for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS). One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the NN PTRS unit 24), processor 38, and / or radio interface 30. Network node 16 such as via processing circuitry 36 and / or processor 38 and / or radio interface 30 is configured to, for a discrete Fourier transform spread orthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determining locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, MPUSCH / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting (Block S10).

[0238] In some embodiments, the locations of the PTRS are based at least in part on a number NgroupsPTRS groups and a number Ngroupsampof samples per PTRS group without muting. In some embodiments, the PTRS locations are based at least in part on Ngroups / 2 PTRS groups. In some embodiments, the PTRS locations are based at least in part on / Vsea™ pP / 2 samples per PTRS group. In some embodiments, PTRS locations withMPUSCH

[0239] indices higher than — - 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, the method includes operating the network node 16 in an Open Radio Access Network (O-RAN).

[0240] FIG. 20 is a flowchart of an example process in a user equipment 22 according to some embodiments of the present disclosure. One or more blocks described herein may be performed by one or more elements of user equipment 22 such as by one or more of processing circuitry 50 (including the UE PTRS unit 26), processor 52, and / or radio interface 46. User equipment 22 such as via processing circuitry 50 and / or processor 52 and / or radio interface 46 is configured to, for a discrete Fourier transform spreadorthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determining locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, MPUSCH / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting (Block S12).

[0241] In some embodiments, the locations of the PTRS are based at least in part on a number NgroupsPTRS groups and a numberNgroupsampof samples per PTRS group without muting. In some embodiments, the PTRS locations are based at least in part on Ngroups / 2 PTRS groups. In some embodiments, the PTRS locations are based at least in part on Ngroupsamp / 2 samples per PTRS group. In some embodiments, PTRS locations withMPUSCH

[0242] indices higher than — - 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, the method includes operating the UE 22 in an Open Radio Access Network (O-RAN).

[0243] In some embodiments, the telecommunication system 10 includes one or more Open-RAN (ORAN) network nodes 16. An ORAN network node 16 is a node in the telecommunication system 10 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication system 10, including one or more network nodes 16 in the access network 12 and / or core network nodes 14.

[0244] FIG. 21 is a flowchart of an example process in a network node 16 or core network node 15 for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS). One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the NN PTRS unit 24), processor 38, and / or radio interface 30. Network node 16 such as via processing circuitry 36 and / or processor 38 and / or radio interface 30 is configured to, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available nonmuted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission (Block S14).In some embodiments, the number of available non-muted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domain locations of PTRS uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node 16 is a core network 15 node in a core network 14. In such instances, the network node would not be in the location of network node 16 as shown in FIG. 16. In some embodiments, the method includes receiving the uplink transmission and obtaining the plurality of PTRS from the determined time domain locations in the uplink transmission.

[0245] FIG. 22 is a flowchart of an example process in a user equipment 22 according to some embodiments of the present disclosure. One or more blocks described herein may be performed by one or more elements of user equipment 22 such as by one or more of processing circuitry 50 (including the UE PTRS unit 26), processor 52, and / or radio interface 46. User equipment 22 such as via processing circuitry 50 and / or processor 52 and / or radio interface 46 is configured to, for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission (Block S16).

[0246] In some embodiments, the number of available non-muted REs is one half of a number of allocated REs for uplink transmission. In some embodiments, the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of PTRSgroups. In some embodiments, the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting. In some embodiments, the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used. In some embodiments, a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting. In some embodiments, determining time domain locations of PTRS uses only a first one half of a number of PTRS groups. In some embodiments, the network node is an Open Radio Access Network (O-RAN) network node. In some embodiments, the network node is a core network node in a core network. In some embodiments, the method includes transmitting the uplink transmission comprising the PTRS in the determined time domain locations.

[0247] Examples of an ORAN network node 16 include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 16 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 22a, 22b, 22c, and 22d (one or more of which may be generally referred to as UEs 22) to the core network 14 over one or more wireless connections.

[0248] FIG. 23 is a block diagram illustrating a virtualization environment 94 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As usedherein, virtualization may be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 94 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 94 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0249] Applications 96 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 94 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0250] Hardware 98 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth.

[0251] Software may be executed by the processing circuitry to instantiate one or more virtualization layers 100 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 102a and 102b (one or more of which may be generally referred to as VMs 102), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 100 may present a virtual operating platform that appears like networking hardware to the VMs 102.

[0252] The VMs 102 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 100. Different embodiments of the instance of a virtual appliance 96 may be implemented on one or more of VMs 102, and the implementations may be made in different ways.

[0253] Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which may be located in data centers, and customer premise equipment.In the context of NFV, a VM 102 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 102, and that part of hardware 98 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 102 on top of the hardware 98 and corresponds to the application 96.

[0254] Hardware 98 may be implemented in a standalone network node with generic or specific components. Hardware 98 may implement some functions via virtualization. Alternatively, hardware 98 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 104, which, among others, oversees lifecycle management of applications 96. In some embodiments, hardware 98 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling may be provided with the use of a control system 106 which may alternatively be used for communication between hardware nodes and radio units.

[0255] Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for resource element (RE) muting for discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) with phase tracking reference signals (PTRS).

[0256] In the following disclosure, the case of RE muting in every other subcarrier is discussed as a nonlimiting example to describe the methods and procedures. The disclosed methods and procedures apply to other RE muting configurations. “Modulated symbols” may here be, e.g., quadrature amplitude modulation (QAM) symbols, quadrature phase shift keying (QPSK) symbols, binary phase shift keying (BPSK) symbols, pi / 2 BPSK symbols, etc. “Non-muted” and “unmuted” are used interchangeably herein.Embodiments

[0257] As described above, for a PUSCH DFT-s-OFDM symbol without muting, MPUSCHmodulated symbols are transform coded using a size MPUSCHDFT into the frequency domain. The transform coded symbols are mapped to the scheduled frequency subcarriers while zeros are inserted to the unscheduled frequency subcarriers. The frequency domain values are then transformed back to the time domain for transmission. In one non-limiting example implementation, this may be based on using a size N IDFT.

[0258] For the specific nonlimiting example case of muting every other subcarrier where there are MPUSCH / 2 modulated symbols, the following muting transform coding procedures may be used in any of the subsequent embodiments:

[0259] 1. Procedure TCI: The length MPUSCH / 2 modulated symbols may be transformed to the frequency domain with a size Mpl, S( H / 2 DFT. The frequency domain values are mapped to the unmuted scheduled subcarriers, which are either (1) even indexed-subcarriers or (2) odd-indexed subcarriers. The muted scheduled subcarriers are set to zero. In one non-limiting example implementation, the frequency domain values are transformed back to the time domain using a size N IDFT.

[0260] 2. Procedure TC2: The length Mpl, S( H / 2 modulated symbols are block spread by [+1, +1] or [+1, —1] into a length MPUSCHmodulated symbols, which are then transformed to the frequency domain with a size MPUSCHDFT. The frequency domain values are mapped to the MPUSCHscheduled subcarriers. In one non-limiting example implementation, the frequency domain values are transformed back to the time domain using a size N IDFT.

[0261] 3. Procedure TC3: The length Mpl, S( H / 2 modulated symbols are block repeated, which are then transformed to the frequency domain with a size MPUSCHDFT. The frequency domain values are either (1) mapped “as is” to the MPUSCHscheduled subcarriers; or (2) cyclically shifted by one before being mapped to the MPUSCHscheduled subcarriers. In one non-limiting example implementation, the frequency domain values are transformed back to the time domain using a size N IDFT.

[0262] 4. Procedure TC4: The length Mpl, S( H / 2 modulated symbols are block repeated, multiplied elementwise by a complex phase ramp exp(— 2n ■ j ■ c ■ m / Mpl, S( H) for m = 0, 1,... MPUSCH— 1, where j is the imaginary unit and c is either 0 or 1, and then transformed to the frequency domain with a size MPUSCHDFT. In one non-limiting example implementation, the frequency domain values are transformed back to the timedomain using a size N ID FT. Alternatively, one may us two other even and odd numbers, e.g., 0 and -1.

[0263] The current 3GPP specifications provide descriptions on how to generate and where to place the PTRS based on the configured number of groups, denoted by Ngroups, and the number of samples per group, denoted by lVfa™pP, as well as the available number of REs denoted by M^JSC l.

[0264] However, for a DFT-s-OFDM symbol with muting, only MPUSCH / 2 REs are available. The following nonlimiting example embodiments are disclosed to construct PTRS for a DFT-s-OFDM symbol with muting.

[0265] In example embodiment Al, the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but with MPUSCHreplaced by MPUSCH / 2. As a nonlimiting example, consider the case of Ngroups= 2 and lVfa™pP= 2. Instead of placing the PTRS at:

[0266] m = MPUSCH / 4] - 1, MPUSCH / 4], 3 MPUSCH / 4] - 1, 3 MPUSCH / 4] which would exceed the available number of subcarriers. This embodiment includes placing the PTRS at:

[0267] m = MPUSCH / 8] - 1, [M 'SCH / 8], 3 [MrscH / 8j - 1, 3 MPUSCH / 8]

[0268] As may be verified from the above listed indices, the PTRS locations are all within the limit of MPUSCH / 2.

[0269] Using the example embodiment Al with any of the transform coding procedures TCI, TC2, TC3, and TC4 listed above, there will be 2 / Vgr^ ~pSgroups of PTRS in the DFT-s-OFDM symbol with muting. For TC2, TC3, and TC4, this is obvious from the block repetition step in the construction. For the TCI method, it may be deduced, e.g., by applying a size MPUSCHID FT of the frequency-domain signal after the mapping to subcarriers, while recalling the well-known mathematical fact that f^1

[0270]

[0271] =[x, x], where fKand fK^2denote the size K discrete Fourier and inverse Fourier transform, respectively, z is the operation of doubling the vector size by interspersing a zero after each element, and [x, x] denotes block repetition of the vector x.

[0272] For the nonlimiting example of Ngroups=

[0273]

[0274] 2 and = 2, there will be PTRS at locations:

[0275] m = [MPUSCH / 8] - 1, [MPUSCH / 8], 3[MPUSCH / 8] - 1, 3[MPUSCH / 8]

[0276]

[0277] MPUSCH / 2 + [MPUSCH / 8] - 1, MPUSCH / 2 + [MPUSCH / 8],MPUSCH / 2 + 3 MPUSCH / 8] - l, MPUSCH / 2 + 3 MPUSCH / 8]

[0278] In other words, the actual time density of PTRS samples is doubled compared to what is configured. The following example embodiments address approaches to avoid doubling the time density.

[0279] In example embodiment A2, the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but with MPUSCHreplaced by Mpl, S( H / 2 and ^groupSreplaced by Agr^ ~pS / 2. In other words, the UE 22 assumes that the actual number of PTRS groups is half the configured value. As a nonlimiting example, consider the case of A grloUuU?)J3= 4 and Asoeadrl°li'pip= 2. Instead of p ITlacing C the PTRS at:

[0280] m = MPUSCH / 8] - 1, MPUSCH / 8], 3MPUSCH / 8] - 1, 3MPUSCH / 8],

[0281] 5MPUSCH / 8] - 1, 5MPUSCH / 8], 7MPUSCH / 8] - 1, 7MPUSCH / 8] This embodiment includes placing the PTRS at:

[0282] m = MPUSCH / 8] - 1, MPUSCH / 8], 3 MPUSCH / 8] - 1, 3 MPUSCH / 8]

[0283] In example embodiment A3, the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but with MPUSCHreplaced by MPUSCH / 2 and only the first As8.™ pP / 2 samples in each group are used. In other words, the UE 22 assumes that the actual number of PTRS samples per group is half the configured value. As a nonlimiting example, consider the case of / Vgr^ ~pS= 2 and A8.™ pP= 2. Instead of placing the PTRS at:

[0284] m = [MPUSCH / 8] - 1, [MPUSCH / 8], 3[MPUSCH / 8] - 1, 3 MPUSCH / 8] This embodiment includes placing the PTRS at:

[0285]

[0286] m = [MPUSCH / 8] - 1, 3[MPUSCH / 8] - 1

[0287] As another nonlimiting example, consider the case of Agr^apS= 4 and A8.™ pP= 2. Instead of placing the PTRS at:

[0288] m = [MPUSCH / 8] - 1, [MPUSCH / 8], [3MPUSCH / 8] - 1, [3MPUSCH / 8],

[0289]

[0290] [5MPUSCH / 8] - 1, [5MPUSCH / 8], [7MPUSCH / 8] - 1, [7MPUSCH / 8] This embodiment includes placing the PTRS at:

[0291] m = MPUSCH / 8] - 1, 3MPUSCH / 8] - 1, 5MPUSCH / 8] - 1, 7MPUSCH / 8] - 1 The PTRS rm(m’') to be mapped in position m before transform precoding is computed as:

[0292] jm mod 2

[0293] rm(m') = w(k')—j=— [(1 — 2c(m')J + / (1 — 2c(m'))]

[0294]

[0295] 31

[0296] m' = N^s' + k'

[0297] s' = 0,1. AgprT0-£s- 1

[0298] £' = 0,1.

[0299]

[0300] <™pP / 2 - l

[0301] In example embodiment A4:

[0302] • the number of groups, Ngroups. and the number of samples per group, ^sampP’316determined according to current 3GPP specifications (i.e., Table 3) by replacing the number of RBs allocated for the PUSCH, NRB, with [1VRB / 2J; and / or

[0303] • the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but with MPUSCHreplaced by Msai / 2.

[0304] In other words, the UE 22 adjusts the number of PTRS groups and number of samples per group based on the actual useable allocated RBs. As a nonlimiting example, consider the case of Ngroups=

[0305]

[0306] 4 and = 2 as determined from Table 3 using the nominally allocated number of RBs, NRB. According to this embodiment, using the actual useable number of RBs, NRB / 2, the UE 22 may determine that / VroupS= 2 and lfa™pP= 4 should be applied instead. Hence, instead of placing the PTRS at:

[0307] m = [MPUSCH / 8] - 1, [MPUSCH / 8], [3MPUSCH / 8] - 1, [3MPUSCH / 8],

[0308] [5MPUSCH / 8] - 1, [5MPUSCH / 8], [7MPUSCH / 8] - 1, [7MPUSCH / 8] This embodiment includes placing the PTRS at:

[0309] m = 0, 1, 2, 3, MPUSCH / 2 - 4, MPUSCH / 2 - 3, MPUSCH / 2 - 2, MPUSCH / 2 - 1, MPUSCH / 2, MPUSCH / 2 + 1, MPUSCH / 2 + 2, MPUSCH / 2 + 3, MsPUSCH- 4, MPUSCH- 3, MPUSCH- 2, MPUSCH- 1 In another nonlimiting example according to this embodiment, the UE 22 may determine that Ngroups= 2 and A^a™ pP= 2 should be applied instead, which would place the PTRS at:

[0310]

[0311] m = [MPUSCH / 8] - 1, [MPUSCH / 8], 3[MPUSCH / 8] - 1, 3[MPUSCH / 8]

[0312] In example embodiment Bl, the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but only the first Ngroups / 2 groups are used. As a nonlimiting example, consider the case of Ngroups= 2 and lfa™pP= 2. This embodiment includes placing the PTRS at:

[0313] m = MPUSCH / 4] - 1, MPUSCH / 4]

[0314] As another nonlimiting example, consider the case of Ngroups= 4 and Nfa^,p= 2. This embodiment includes placing the PTRS at:m = MPUSCH / 8] - 1, |MPUSCH / 8], 3MPUSCH / 8] - 1, 3MPUSCH / 8], That is, the locations of the PTRS are determined according to current 3GPP specifications (i.e., Table 4) but the PTRS located in indices higher than Mpl, S( H / 2 — 1 are not used. The PTRS rm(rn') to be mapped in position m before transform precoding is computed as:

[0315] jm mod 2

[0316] hn(m') = w(k'y [(1 - 2c(m')) +j(l - 2c(m'))]

[0317] = N^s' + k’

[0318] s' = 0,1. AgP70-£s / 2 - 1

[0319]

[0320] fc' = o,i. Cp- i Embodiments on Extensions to Larger Combs

[0321] In some embodiments, TCI and A1 / A3 are generalized to comb-A with N > 2. The quantity Msai / 2 is then to be replaced by MPUSCH■ (A — 1) / A in the description of the methods.

[0322] 0-RAN -Related Embodiments

[0323] In some embodiments, the following is signaled from the O-DU to the O-RU over the fronthaul interface in an O-RAN-based base station:

[0324] 1. PTRS configuration for each UE 22;

[0325] 2. UL muting pattern for each UE 22. Depending on which of TCI, 2, 3, or 4 is used, the needed indication is either:

[0326] a. whether even / odd sub-carriers are mapped;

[0327] b. what OCC is used; and / or

[0328] c. phase ramp indication.

[0329] The signaling may be over the control plane, management plane, or a combination of both.

[0330] Some embodiments may include one or more of the following:

[0331] Embodiment Al. A network node configured to communicate with a user equipment (UE), the network node configured to, and / or comprising a radio interface and / or comprising processing circuitry configured to:

[0332] for a discrete Fourier transform spread orthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determine locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, MPUSCH / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting.Embodiment A2. The network node of Embodiment Al, wherein the locations of the PTRS are based at least in part on a number lVroupSPTRS groups and a number ^sampP°f samples per PTRS group without muting.

[0333] Embodiment A3. The network node of Embodiment A2, wherein the PTRS locations are based at least in part on lVroupS / 2 PTRS groups.

[0334] Embodiment A4. The network node of any of Embodiments A2 and A3, wherein the PTRS locations are based at least in part on iVa^pP / 2 samples per PTRS group.

[0335] Embodiment A5. The network node of any of Embodiments A2-A4, whereinMPUSCH PTRS locations with indices higher than — - 1 are not used.

[0336] Embodiment A6. The network node of any of Embodiments A1-A5, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting.

[0337] Embodiment A7. The network node of any of Embodiments A1-A6, wherein the network node is an Open Radio Access Network (O-RAN) network node.

[0338] Embodiment A8. The network node of any of Embodiments A1-A7, wherein the network node is a core network node in a core network.

[0339] Embodiment Bl. A method implemented in a network node that is configured to communicate with a user equipment (UE), the method comprising:

[0340] for a discrete Fourier transform spread orthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determining locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, MPUSCH / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting.

[0341] Embodiment B2. The method of Embodiment B 1, wherein the locations of the PTRS are based at least in part on a number NgroupsPTRS groups and a number lVfa™pPof samples per PTRS group without muting.

[0342] Embodiment B3. The method of Embodiment B2, wherein the PTRS locations are based at least in part on lVroupS / 2 PTRS groups.

[0343] Embodiment B4. The method of any of Embodiments B2 and B3, wherein the PTRS locations are based at least in part on Nfa^,p / 2 samples per PTRS group.Embodiment B5. The method of any of Embodiments B2-B4, wherein PTRSMPUSCH

[0344] locations with indices higher than — - 1 are not used.

[0345] Embodiment B6. The method of any of Embodiments B1-B5, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting.

[0346] Embodiment B7. The method of any of Embodiments B1-B6, further comprising operating the network node in an Open Radio Access Network (O-RAN).

[0347] Embodiment B8. The method of any of Embodiments B1-B7, wherein the network node operates as a core network node in a core network.

[0348] Embodiment Cl. A user equipment (UE) configured to communicate with a network node, the UE configured to, and / or comprising a radio interface and / or processing circuitry configured to:

[0349] for a discrete Fourier transform spread orthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determine locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, MPUSCH / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting.

[0350] Embodiment C2. The UE of Embodiment Cl, wherein the locations of the PTRS are based at least in part on a number NgroupsPTRS groups and a number lfa™pPof samples per PTRS group without muting.

[0351] Embodiment C3. The UE of Embodiment C2, wherein the PTRS locations are based at least in part on / VroupS / 2 PTRS groups.

[0352] Embodiment C4. The UE of any of Embodiments C2 and C3, wherein the PTRS locations are based at least in part on Ws8.™ pP / 2 samples per PTRS group.

[0353] Embodiment C5. The UE of any of Embodiments C2-C4, wherein PTRSMPUSCH

[0354] locations with indices higher than — - 1 are not used.

[0355] Embodiment C6. The UE of any of Embodiments C1-C5, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting.

[0356] Embodiment C7. The UE of any of Embodiments C1-C6, wherein the UE is configured to communicate with an Open Radio Access Network (O-RAN) network node.

[0357] Embodiment DI. A method implemented in a user equipment (UE) that is configured to communicate with a network node, the method comprising:for a discrete Fourier transform spread orthogonal frequency division multiplexed (DFT-s-OFDM) symbol with muting, determining locations of a plurality of phase tracking reference signals (PTRS) within a limit of MPUSCH / 2, Mpl, S( H / 2 being a number of available resource elements (REs) with muting, MPUSCHbeing a number of available REs without muting.

[0358] Embodiment D2. The method of Embodiment DI, wherein the locations of the PTRS are based at least in part on a number NgroupsPTRS groups and a number lVsea™ pPof samples per PTRS group without muting.

[0359] Embodiment D3. The method of Embodiment D2, wherein the PTRS locations are based at least in part on lVroupS / 2 PTRS groups.

[0360] Embodiment D4. The method of any of Embodiments D2 and D3, wherein the PTRS locations are based at least in part on Nfa^,p / 2 samples per PTRS group.

[0361] Embodiment D5. The method of any of Embodiments D2-D4, wherein PTRSMPUSCH

[0362] locations with indices higher than — - 1 are not used.

[0363] Embodiment D6. The method of any of Embodiments D1-D5, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting.

[0364] Embodiment D7. The method of any of Embodiments D1-D6, further comprising operating the UE in an Open Radio Access Network (O-RAN).

[0365] As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and / or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and / or functionality described herein may be performed by, and / or associated to, a corresponding module, which may be implemented in software and / or firmware and / or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that may be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.Some embodiments are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0366] These computer program instructions may also be stored in a computer readable memory or storage medium that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0367] The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0368] It is to be understood that the functions / acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

[0369] Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, suchas the " C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0370] Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments may be combined in any way and / or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

[0371] Abbreviations that may be used in the preceding description include:

[0372] Abbreviation Explanation

[0373] BSPK Binary phase shift keying

[0374] CM Cubic Metric

[0375] CP Cyclic prefix

[0376] DFT Discrete Fourier transform

[0377] DFT-s-OFDM DFT-spread OFDM

[0378] DL Downlink

[0379] gNB gNodeB (basestation)

[0380] IDFT Inverse discrete Fourier transform MCS Modulation and coding scheme OFDM Orthogonal frequency domain modulation PAPR Peak-to-average power ratio

[0381] PRB Physical resource block

[0382] PTRS, PT-RS Phase-tracking reference signals QAM Quadrature amplitude modulation QPSK Quadrature phase shift keying PDSCH Physical downlink shared channelPUSCH Physical uplink shared channel RE Resource Element

[0383] SBFD Subband full duplex

[0384] TDD Time-division duplex

[0385] TX Transmitter, transmission UE User Equipment

[0386] UL Uplink

[0387] It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.

Claims

What is claimed is:

1. A method in a user equipment, UE, (22), configured to communicate with a network node (16), the method comprising:for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining (SI 6) time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

2. The method of Claim 1, wherein the number of available non-muted REs is one half of a number of allocated REs for uplink transmission.

3. The method of any of Claims 1 and 2, wherein the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting.

4. The method of Claim 3, wherein the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups.

5. The method of Claim 3, wherein the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting.

6. The method of Claim 3, wherein the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used.

7. The method of any of Claims 1-6, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel, PUSCH, with muting is one half a number of RBs allocated for PUSCH without muting.

8. The method of any of Claims 1-7, wherein determining time domain locations of PTRS uses only a first one half of a number of PTRS groups.

9. The method of any of Claims 1-8, wherein the network node (16) is an Open Radio Access Network, O-RAN, network node (16).

10. The method of any of Claims 1-8, wherein the network node (16) is a core network node (15) in a core network (14).

11. The method of any of Claims 1-10, further comprising transmitting the uplink transmission comprising the PTRS in the determined time domain locations.

12. A user equipment, UE (22), configured to communicate with a network node (16), the UE (22) comprising processing circuitry (50) configured to:for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

13. The UE (22) of Claim 12, wherein the number of available non-muted REs is one half of a number of allocated REs for uplink transmission.

14. The UE (22) of any of Claims 12 and 13, wherein the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting.

15. The UE (22) of Claim 14, wherein the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups.

16. The UE (22) of Claim 14, wherein the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting.

17. The UE (22) of Claim 14, wherein the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used.

18. The UE (22) of any of Claims 12-17, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel, PUSCH, with muting is one half a number of RBs allocated for PUSCH without muting.

19. The UE (22) of any of Claims 12-18, wherein determining time domain locations of PTRS uses only a first one half of a number of PTRS groups.

20. The UE (22) of any of Claims 12-19, wherein the network node (16) is an Open Radio Access Network, O-RAN, network node (16).

21. The UE (22) of any of Claims 12-19, wherein the network node (16) is a core network node (15) in a core network (14).

22. The UE (22) of any of Claims 12-21, wherein the processing circuitry (50) is further configured to cause transmission of the uplink transmission comprising the PTRS in the determined time domain locations.

23. A method in a network node (16) configured to communicate with a user equipment, UE (22), the method comprising:for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining (S14) time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number of available non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

24. The method of Claim 23, wherein the number of available non-muted REs is one half of a number of allocated REs for uplink transmission.

25. The method of any of Claims 23 and 24, wherein the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting.

26. The method of Claim 25, wherein the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups.

27. The method of Claim 25, wherein the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting.

28. The method of Claim 25, wherein the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used.

29. The method of any of Claims 23-28, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel, PUSCH, with muting is one half a number of RBs allocated for PUSCH without muting.

30. The method of any of Claims 23-29, wherein determining time domain locations of PTRS uses only a first one half of a number of PTRS groups.

31. The method of any of Claims 23-30, wherein the network node (16) is an Open Radio Access Network, O-RAN, network node (16).

32. The method of any of Claims 23-30, wherein the network node (16) is a core network node (15) in a core network (14).

33. The method of any of Claims 23-32, further comprising:receiving the uplink transmission; andobtaining the plurality of PTRS from the determined time domain locations in the uplink transmission.

34. A network node (16) configured to communicate with a user equipment, UE (22), the network node (16) comprising processing circuitry (36) configured to:for a discrete Fourier transform spread orthogonal frequency division multiplexed, DFT-s-OFDM, symbol with muting, determining time domain locations of a plurality of phase tracking reference signals, PTRS, within a limit, the limit being a number ofavailable non-muted resource elements, REs, the available non-muted REs being a subset of allocated REs for uplink transmission.

35. The network node (16) of Claim 34, wherein the number of available nonmuted REs is one half of a number of allocated REs for uplink transmission.

36. The network node (16) of any of Claims 34 and 35, wherein the time domain locations of the PTRS are based at least in part on a number of PTRS groups and a number of samples per PTRS group without muting.

37. The network node (16) of Claim 36, wherein the time domain locations of the PTRS are based at least in part on one half the number of PTRS groups.

38. The network node (16) of Claim 36, wherein the time domain locations of the PTRS are based at least in part on one half the number of samples per PTRS group without muting.

39. The network node (16) of Claim 36, wherein the time domain locations of the PTRS with indices higher than one half the number of allocated REs for uplink transmission minus 1 are not used.

40. The network node (16) of any of Claims 34-39, wherein a number of resource blocks (RBs) allocated for a physical uplink shared channel (PUSCH) with muting is one half a number of RBs allocated for PUSCH without muting.

41. The network node (16) of any of Claims 34-40, wherein determining time domain locations of PTRS uses only a first one half of a number of PTRS groups.

42. The network node (16) of any of Claims 34-41, wherein the network node (16) is an Open Radio Access Network, O-RAN, network node (16).

43. The network node (16) of any of Claims 34-42, wherein the network node (16) is a core network node (15) in a core network (14).

44. The network node (16) of any of Claims 34-43, wherein the processing circuitry (36) is configured to:receive the uplink transmission; andobtain the plurality of PTRS from the determined time domain locations in the uplink transmission.

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