WO2020069455A1 - Peak-to-average power ratio (papr) reduction in reference signals - Google Patents

Abstract

Technology for a Next Generation NodeB (gNB) operable to generate a downlink reference signal having a reduced peak-to-average power ratio (PAPR) is disclosed. The gNB can map complex pseudo noise (PN) sequence symbols to one or more codedivision- multiplexed (CDM)-Groups. The gNB can perform, on each CDM-Group of the one or more CDM-Groups, a CDM-Group specific linear non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the downlink reference signal having the reduced PAPR. The gNB can encode, at the gNB, the downlink reference signal having the reduced PAPR for transmission to a user equipment (UE).

Description

PEAK-TO-AVERAGE POWER RATIO (PAPR)

REDUCTION IN REFERENCE SIGNALS

BACKGROUND

[0001] Wireless systems typically include multiple User Equipment (UE) devices communicatively coupled to one or more Base Stations (BS). The one or more BSs may be Long Term Evolved (LTE) evolved NodeBs (eNB) or New Radio (NR) next generation NodeBs (gNB) that can be communicatively coupled to one or more UEs by a Third- Generation Partnership Project (3GPP) network.

[0002] Next generation wireless communication systems are expected to be a unified network/system that is targeted to meet vastly different and sometimes conflicting performance dimensions and services. New Radio Access Technology (RAT) is expected to support a broad range of use cases including Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), Mission Critical Machine Type Communication (uMTC), and similar service types operating in frequency ranges up to 100 GHz.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosure; and, wherein:

[0004] FIG. 1 illustrates a block diagram of a Third-Generation Partnership Project (3GPP) New Radio (NR) Release 15 frame structure in accordance with an example;

[0005] FIG. 2 illustrates New Radio (NR) Release-l5 demodulation reference signal (DM-RS) types in accordance with an example;

[0006] FIG. 3 illustrates a PAPR degradation in Release 15 single symbol Type 1 and Type 2 DMRS in accordance with an example;

[0007] FIG. 4 illustrates a PAPR improvement in Type 1 DMRS in accordance with an example;

[0008] FIG. 5 illustrates a PAPR improvement in Type 1 DMRS in accordance with an example;

[0009] FIG. 6 illustrates a code-division-multiplexed (CDM) group specific Cmtt based pseudo-random (PN) sequence generation and mapping in accordance with an example;

[0010] FIG. 7 depicts functionality of a user equipment (UE) operable to generate a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR) in accordance with an example;

[0011] FIG. 8 depicts functionality of a Next Generation NodeB (gNB) operable to generate a downlink reference signal having a reduced peak-to-average power ratio (PAPR) in accordance with an example;

[0012] FIG. 9 depicts functionality of a generating a demodulation reference signal (DM-

RS) having a reduced peak-to-average power ratio (PAPR) in accordance with an example;

[0013] FIG. 10 illustrates an architecture of a wireless network in accordance with an example;

[0014] FIG. 11 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example;

[0015] FIG. 12 illustrates interfaces of baseband circuitry in accordance with an example; and

[0016] FIG. 13 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example.

[0017] Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. DETAILED DESCRIPTION

[0018] Before the present technology is disclosed and described, it is to be understood that this technology is not limited to the particular structures, process actions, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element. Numbers provided in flow charts and processes are provided for clarity in illustrating actions and operations and do not necessarily indicate a particular order or sequence.

DEFINITIONS

[0019] As used herein, the term“User Equipment (UE)” refers to a computing device capable of wireless digital communication such as a smart phone, a tablet computing device, a laptop computer, a multimedia device such as an iPod Touch®, or other type computing device that provides text or voice communication. The term“User Equipment (UE)” may also be referred to as a "mobile device," "wireless device," of "wireless mobile device."

[0020] As used herein, the term“Base Station (BS)” includes“Base Transceiver Stations (BTS),”“NodeBs,”“evolved NodeBs (eNodeB or eNB),”“New Radio Base Stations (NR BS) and/or“next generation NodeBs (gNodeB or gNB),” and refers to a device or configured node of a mobile phone network that communicates wirelessly with UEs.

[0021] As used herein, the term“cellular telephone network,”“4G cellular,”“Long Term Evolved (LTE),”“5G cellular” and/or“New Radio (NR)” refers to wireless broadband technology developed by the Third Generation Partnership Project (3GPP).

EXAMPLE EMBODIMENTS

[0022] An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter.

[0023] FIG. 1 provides an example of a 3GPP NR Release 15 frame structure. In particular, FIG. 1 illustrates a downlink radio frame structure. In the example, a radio frame 100 of a signal used to transmit the data can be configured to have a duration, T/, of 10 milliseconds (ms). Each radio frame can be segmented or divided into ten subframes llOi that are each 1 ms long. Each subframe can be further subdivided into one or multiple slots l20a, l20i, and l20x, each with a duration, T slot, of 1 / m ms, where m = 1 for l5kHz subcarrier spacing, m = 2 for 30kHz, m = 4 for 60kHz, m = 8 for 120kHz, and u = 16 for 240kHz. Each slot can include a physical downlink control channel (PDCCH) and/or a physical downlink shared channel (PDSCH).

[0024] Each slot for a component carrier (CC) used by the node and the wireless device can include multiple resource blocks (RBs) l30a, l30b, 130i, l30m, and 130h based on the CC frequency bandwidth. The CC can have a carrier frequency having a bandwidth. Each slot of the CC can include downlink control information (DCI) found in the PDCCH. The PDCCH is transmitted in control channel resource set (CORESET) which can include one, two or three Orthogonal Frequency Division Multiplexing (OFDM) symbols and multiple RBs.

[0025] Each RB (physical RB or PRB) can include 12 subcarriers (on the frequency axis) and 14 orthogonal frequency-division multiplexing (OFDM) symbols (on the time axis) per slot. The RB can use 14 OFDM symbols if a short or normal cyclic prefix (CP) is employed. The RB can use 12 OFDM symbols if an extended cyclic prefix is used. The resource block can be mapped to 168 resource elements (REs) using short or normal cyclic prefixing, or the resource block can be mapped to 144 REs (not shown) using extended cyclic prefixing. The RE can be a unit of one OFDM symbol 142 by one subcarrier (i.e., 15 kHz, 30kHz, 60kHz, l20kHz, and 240kHz) 146.

[0026] Each RE l40i can transmit two bits l50a and l50b of information in the case of quadrature phase-shift keying (QPSK) modulation. Other types of modulation may be used, such as 16 quadrature amplitude modulation (QAM) or 64 QAM to transmit a greater number of bits in each RE, or bi-phase shift keying (BPSK) modulation to transmit a lesser number of bits (a single bit) in each RE. The RB can be configured for a downlink transmission from the eNodeB to the UE, or the RB can be configured for an uplink transmission from the UE to the eNodeB.

[0027] This example of the 3GPP NR Release 15 frame structure provides examples of the way in which data is transmitted, or the transmission mode. The example is not intended to be limiting. Many of the Release 15 features will evolve and change in the 5G frame structures included in 3GPP LTE Release 15, MulteFire Release 1.1, and beyond. In such a system, the design constraint can be on co-existence with multiple 5G numerologies in the same carrier due to the coexistence of different network services, such as eMBB (enhanced Mobile Broadband), mMTC (massive Machine Type

Communications or massive IoT) and URLLC (Ultra Reliable Low Latency

Communications or Critical Communications). The carrier in a 5G system can be above or below 6GHz. In one embodiment, each network service can have a different numerology.

[0028] In one configuration, in Release- 15 NR, a demodulation reference signal (DMRS) is a user specific reference signal which can be used for channel estimation for physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) data demodulation. In Rel-l5 NR, a DM-RS is generated using a length 31 Gold Sequence similar to LTE, in the case when a CP-OFDM waveform is used for the PDSCH and the PUSCH. Zadoff-Chu (ZC) sequences can be used for a Discrete Fourier Transform (DFT) spread Orthogonal Frequency Division Multiplexing (OFDM) (i.e., when transform precoding is enabled) waveform for the PUSCH. There can be two different DM-RS configurations, configuration Type 1 and Type 2. Type 1 DM-RS has 2 code-division- multiplexed (CDM) port groups with each group occupying 6 orthogonal frequency resource elements (REs) within a physical resource block (PRB) on a single OFDM symbol. Type 1 single symbol DM-RS can support a maximum of 4 orthogonal DMRS ports with 2 DM-RS ports multiplexed within each CDM-group using frequency domain orthogonal cover codes (FD-OCC). Type 2 DM-RS has 3 CDM port groups with each group occupying 4 orthogonal REs within a PRB on a single OFDM symbol. Type 2 single symbol DM-RS can support a maximum of 6 orthogonal DMRS ports with each CDM-group having 2 DM-RS ports multiplexed using FD-OCC. Furthermore, both Type 1 and Type 2 DM-RS can occupy two OFDM symbols with ports multiplexed using time- domain (TD) OCC in addition to FD-OCC. Two-symbol Type 1 DM-RS can support a maximum of 8 ports with 4 ports in each CDM-Group. Two-symbol Type 2 DM-RS can support a maximum of 12 orthogonal ports with 4 ports in each CDM-Group.

[0029] In one example, the length 31 -Gold sequence is mapped to DM-RS ports such that the sequence values are identical (before applying precoder and OCC) for all DMRS ports, which can lead to an increase in peak-to-average power ratio (PAPR) of the time domain OFDM signal for some specific cases of configuration, e.g., when only port 0 and port 2 are configured together for Type 1 and Type 2 DMRS and non-diagonal precoders are used, or when ports 0-3 or higher are configured for Type 1 and Type 2 DMRS and non-diagonal precoders are used.

[0030] In one example, a similar problem exists for channel state information (CSI) reference signals, and the solution described below can similarly apply for CSI-RS.

[0031] In one configuration, a NR multiple-input multiple-output (MIMO) low PAPR reference signal design is described herein. The low PAPR reference signal design can implement a PAPR reduction in reference signals. The PAPR reduction can be achieved by randomizing the time-domain sequences corresponding to different ports or corresponding to ports belonging to different CDM groups using mathematical operations. For example, three different techniques for randomization can be used as follows: (1) using a CDM-Group specific sequence operation such as complex conjugation; (2) using a CDM-Group specific time domain cyclic shift; or (3) using

CDM-Group specific initialization values for generating uniquely random sequences for each CDM-Group.

[0032] FIG. 2 illustrates an example of New Radio (NR) Release- 15 demodulation reference signal (DM-RS) types. In NR Release-l5, two different DM-RS types are used, namely Type-l and Type-2 DM-RS. For a single symbol case, Type 1 DMRS can use a comb-2 structure with 2 CDM-Groups and length-2 FD-OCC per pair of alternating REs in each CDM-Group, while Type 2 DMRS can use a comb-3 structure with 3 CDM- Groups and length-2 FD-OCC per pair of adjacent REs in each CDM-Group. The length- 2 FD-OCC is given by [i i_{, i -i}] . For the case of a CP-OFDM waveform, both Type 1 and Type 2 DM-RS can use a complex quadrature phase shift keying (QPSK) sequence r(n) generated as

where c(i) is a pseudo-random length-31 Gold sequence initialized by:

[0033] In one example, the generated sequence is then mapped to the physical resources as follows: (2n + k')

Configuration type 1

(UL)

Configuration type 2

k' = 0, 1; / = / + l';n = 0, 1, ... ; j = 0, 1, ..., u - 1

[0034] In one example, values of the different parameters k ' . h. A are specified in 3GPP TS 38.211 vl5. l.0, NR Physical Channels and Modulation (Release 15), Tables 6.4.1.1.3-1 and 7.4.1.1.2-1 respectively for uplink and downlink. Following the sequence mapping, the DM-RS is pre-coded and transmitted from physical antenna ports. Note that DM-RS ports are equivalent to MIMO layers and not physical antenna ports. The precoding is performed as follows:

[0035] In one example, this precoder is applied per sub-carrier for all the sub-carriers within the same PRG. The dimensions of the precoder matrix are [ ] i.e., number of antenna ports times the number of MIMO layers. The mapping of MIMO layers or DMRS antenna ports follows the comb/sub-carrier structure defined by each DMRS Type. For example, consider the case of single symbol DM-RS Type 2 with 6 DM-RS ports i.e., u = 6. In this case, for the first sub-carrier in the PRB, the precoder will be applied only to ports 0, 1 since these are the only ports in the I^st CDM-Group. The remaining ports are replaced with zeros and the precoding will be as follows:

[0036] In one example, for antenna port 0, the precoding can be expressed in terms of the first row of the precoder matrix as:

[0037] Based on the NR Rel-l5 sequence mapping, the mapping r(2n + k ') is independent of the CDM-Group i.e., ports within each CDM-Group share the same DMRS sequence values. Due to this mapping structure, when two ports from different

CDM-Groups have identical FD-OCC values, they also have identical values of <¾^/ _/ ⁾ , for adjacent subcarriers. For example, the case of Type 1 DMRS with scheduling of ports 0, 2 which belong to CDM-Groups 1 and 2 respectively with identical FD-OCC values,

_<¾^o) = a[^p, ^{2 )} = r(0)

can lead to the case where:

[0038] For this example, consider a precoding matrix such thatRj, ₀, W_{n 2} = 1. After precoding considering all the sub-carriers within a PRB, the DMRS sequence is repeated in the frequency domain, as follows:

[0039] Similarly for DM-RS Type 2, the repetition of the sequence values for the case when ports 0, 2 are scheduled are of the following form:

[0040] In one example, this repetition of the DMRS sequence in the frequency domain can lead to a coherent combination of signals in the time domain post inverse fast Fourier transform (IFFT) for OFDM symbol generation, leading to a degradation in PAPR in comparison to CP-OFDM with random QPSK in every sub-carrier. This issue can occur for most non-diagonal pre-coders. Similar issues can potentially occur in the case of Type 2 DMRS. Furthermore, in the case when all possible layers are scheduled for both Type 1 and Type 2 DMRS, the degradation still exists for some non-diagonal pre-coders and antenna ports. [0041] FIG. 3 illustrates an example of PAPR degradation in Release 15 single symbol Type 1 and Type 2 DMRS. A plot is shown of a complementary cumulative distribution function (CCDF) of the per antenna port PAPR of Rel-l5 DMRS for all possible precoding matrix indicators (PMIs) for each rank. For fully loaded cases, the PAPR across all antenna ports and pre-coders is degraded for the Rel-l5 DMRS design due to the fact that same sequence values are mapped to multiple CDM-Groups. This issue is common to both DL and UL operation. However, the case of UL with Type 2 DMRS is limited to rank-4 operation, and therefore, the problems for both Type 1 and Type 2 are identical since, from a UE perspective, all 3 CDM-Groups are never simultaneously scheduled.

[0042] In one configuration, techniques are described to address the high PAPR issue of

Release- 15 NR DM-RS sequence mapping.

[0043] In one example, conjugate sequences can be used for Type 1 and Type 2 DM-RS. In this example, for Type 1 and 2 DM-RS, the sequence mapping of Rel-l5 NR is used to map complex QPSK PN sequence to the ports within the first CDM Group in the frequency domain. For the ports within the second CDM-Group, a complex conjugate of the sequence values in the first comb can be used. The use of complex conjugate sequences in the frequency domain can lead to a time-reversed circularly shifted sequence in the time domain corresponding to the second CDM-Group. This leads to a reduction in PAPR of the time domain OFDM symbol.

[0044] An example of this mapping for Type 1 DM-RS is as follows:

') for A = 0

r(2n + k '

k') ffor A = 1

k = 4n + Configuration Type 1

£' = 0,1;

0,1

[0045] Here r * (2 n + k ') denotes the complex conjugate of the sequence values r(2n + k ')

[0046] FIG. 4 illustrates an example of a PAPR improvement in Type 1 DMRS. The PAPR improvement in Type 1 DMRS is achieved using the preceding technique of using conjugate sequences for Type 1 DM-RS.

[0047] In one example, for Type 2 DM-RS, the following can be used: Rel-l5 NR DM RS mapping in CDM-Group 1, the conjugate of the sequence values of CDM-Group 1 mapped to ports in CDM-Group 2, and a complex phase shift of e ^{J kn} applied to the sequence values of CDM-Group 1 and mapped to ports in CDM-Group 3. The phase shift of the sequence values in CDM-Group 3 can lead to a time domain circular shift of N/4, where N is the IFFT size. This decreases the PAPR of the overall OFDM signal.

[0048] An example of this mapping for Type 2 DM-RS is as follows:

1

[0049] FIG. 5 illustrates an example of a PAPR improvement in Type 2 DMRS. The PAPR improvement in Type 2 DMRS is achieved using the preceding technique of using conjugate sequences for Type 2 DM-RS.

[0050] In one example, this technique can reduce PAPR for all non-diagonal pre-coders that can be applied to DM-RS. The technique applies equally to downlink and uplink DMRS.

[0051] In one example, a phase shift only approach can be used, whereby a CDM-Group specific phase shift is applied to all the sequence values in CDM-Group 2 for Type 1 DMRS and CDM Groups 2 and 3 for Type 2 DMRS.

[0052] For example, for Type 1 DM-RS, the sequence values r(2n + k ') can be mapped to the first CDM-Group while for the second CDM-Group, a CDM-group specific phase- shift of e ^{J kn} can be applied to the sequence values i.e., the sequence values e ^{! k i}r(2n + k ') can be mapped to the ports in CDM-Group 2. This would decrease PAPR of the OFDM symbol carrying DM-RS. The phase shifts take values in the set

[i -J -i J] ·

[0053] In another example, for Type 2 DM-RS, the sequence values r(2n + k ') can be mapped to the first CDM-Group. For the second CDM-Group, a CDM-group specific phase-shift of e ^{] kn} can be applied to the sequence values i.e., the sequence values e ^{1 kn}r{2n + k ') can be mapped to the ports in CDM-Group 2. This would decrease PAPR of the OFDM symbol. For the third CDM-Group, a phase shift of e ^]Mi can be applied to the sequence values of CDM-Group 1 i.e., the sequence values e ^J’^klir(2n + k ') can be mapped to the ports in CDM Group 3. This reduces the PAPR of the OFDM symbol carrying DM-RS.

[0054] In yet another example, a phase shift of b ^]LI6 applied to sequence values in CDM-Group 2 and e ^{J k 112} applied to CDM-Group 3 also reduces PAPR of the OFDM Symbol carrying DM-RS.

[0055] In one example, CDM-Group specific phase shifts can be applied to sequence values mapped to different CDM-Groups for CSI-RS to reduce PAPR of the OFDM symbol carrying CSI-RS.

[0056] For example, for CSI-RS. the sequence mapping from Release 15 NR can be used for the first CDM-Group. For the remaining CDM-Groups, CDM-Group specific phase- shifts the form e ^{2< 1} can be applied to sequences mapped to CDM-Groups

N _cdm e {2, 3, ... , 6} . This can reduce the PAPR of the OFDM symbol carrying CSI-RS.

[0057] In one example, different sequences can be generated for each CDM-Group for both Type 1 and Type 2 DM-RS by making the PN sequence initialization CDM-Group specific.

[0058] As an example, for generating CDM-Group specific PN sequences, the following initialization can be used for the length-31 Gold sequence:

where N_cim is the total number of CDM groups. A^, _cdm = 2 for DM-RS Type 1 and

A^, _cdm = 3 for DM-RS Type 2. n_CDMID e {0, 1, 2} is the ID associated with the CDM-Group for which the sequence is being generated. Therefore, the proposed c is CDM-Group specific. The sequence values generated using this c can be denoted by

(n) , which are then mapped to the CDM-Group n_CDMID as per

(2 n + k ') .

[0059] FIG. 6 illustrates an example of a CDM group specific emit based pseudo-random (PN) sequence generation and mapping. For the CDM group specific c_,nH based PN sequence generation and mapping, two sequences can be used for DMRS Type 1, while up to 3 sequences can be used for DMRS Type 2.

[0060] In one example, for DMRS Type 2, the following initialization of the Gold

Sequence can be used for PDSCH and PUSCH based on CP-OFDM waveform:

[0061] In another example, n_CDMID = D where D is specified in 3GPP TS 38.211 vl5. l.0, NR Physical Channels and Modulation (Release 15).

[0062] The above example can also be extended to the case of two-symbol DMRS and for any additional DMRS which may be configured in the later part of the slot. In the following, additional techniques of CDM group specific c_imt generation are described.

[0063] In one example, for DMRS Type 1, the original Release- 15 c_{in r} can be used for the first CDM-group (ports 0, 1, for one symbol DMRS and ports 0,1, 4, 5 for 2 symbol DMRS) i. e. , c⁰ _itjl = ( 2‘ ' (N^, ^ 1 1) ( 2L¾™ + 1 ) 2L¾^au -·- ¾_CiD J mod 2^J‘ . In this case, a scrambling ID n_sr;D e {0,1} can be signaled using DCI 0 1 for UL and 1 1 for DL with a cyclic redundancy check (CRC) scrambled by a cell radio network temporary identifier (C-RNTI), configured scheduling cell radio network temporary identifier (CS-RNTI) or a modulation coding scheme cell radio network temporary identifier (MCS-C-RNTI). For the second, CDM-group (ports 2, 3 for one symbol DMRS and 2, 3, 6, 7 for two symbol DMRS), the following

can be used: mod 2^Jl

[0064] In one example, for multi-transmission reception point (TRP) operation or dynamic TRP switching, the UE can be configured with n_saD = 0 for one TRP and n_sclD ^::: Ifor another TRP. Such a solution would incur no additional RRC impact as compared to Release- 15 NR.

[0065] In one example, for the case of a default DMRS configuration by DCI formats 1 0 for DL and 0 0 UL or DMRS configuration using DCI formats with CRC scrambled by RNTIs other than C-RNTI, CS-RNTI or MCS-C-RNTI, the UE can use the same initialization as in legacy Release- 15 NR with the default value of /?_{S( i!,} = 0. [0066] In one example, for DMRS Type 1, any two of the following e_¾t. values can be used for each CDM-group based on the « _C]D indicated by the DCI:

[0067] In one example, for DMRS Type 2, any three of the following c._tyi values can be used for each CDM-group based on the n_SCSD indicated by the DCI:

[0068] In one example, when the UE is configured with M_SC!D e {0,1} by DCI format l_l for DL and 0 1 for UL with CRC scrambled by C-RNTI, CS-RNTI or MCS-C-RNTI, the following e_{m t} can be used in the three CDM-groups:

where can be given by any of the following:

lly shifted version of i¥_ro by s bits

[0069] In one example, for multi-TRP operation or dynamic TRP switching, the UE can be configured with «_SCID = 0 for one TRP and n_scm = 1 for another TRP. Such a solution would incur no additional RRC impact compared to Rel-l5 NR.

[0070] In one example, a UE can be higher layer configured (using radio resource control (RRC) signaling) with two sets each containing two l6-bit V,_D values. Set 1 contains values {A^ ₀, N)_{D 0}} and Set 2 contains values {N , , N)_D , } . I n the case that only CDM-

Group 1 and 2 are used, the following initialization values can be used for the two CDM groups:

where n_{scm -} 1 /¾_CID and A^’J indicates IDs from set 1

[0071] In this case, the scrambling ID n_SCID e {0, 1} can be signaled using DCI 0_l for UL and 1 1 for DL with CRC scrambled by the C-RNTI, CS-RNTI or MCS-C-RNTI. In the case that the third CDM-Group is used, the following initialization can be used in the third CDM-group using the configured value of n_SCID e {0,1} and

values from Set 2:

[0072] In one example, for multi-TRP operation or dynamic TRP switching, the UE can be configured with n_scm = 0 for one TRP and «_SCiD = 1 for another TRP. Such a solution would maintain maximum backward compatibility with Release- 15 NR.

[0073] In one example, the sequence for one of the CDM groups for DM-RS type 2 can be also obtained using an XOR operation of the two sequences generated by

= 1 - «_SC1D .

[0074] In one example, a choice of using the Release- 15 cw, or the new proposed c_,nit for Release- 16 can be configured to the UE by a higher layer RRC parameter.

[0075] In one configuration, a technique is described for PAPR reduction of downlink and uplink reference signals by performing CDM-Group specific non-linear operations on complex PN sequence symbols mapped to each CDM-Group. The reference signals can be DM-RS and/or CSI-RS.

[0076] In one example, CDM-Group specific shifts can be applied to sequence values mapped to ports in CDM-Group 2 in Type 1 DMRS. In another example, CDM-Group specific shifts can be applied to sequence values mapped to ports in CDM-Group 2 and a different CDM-Group specific phase shift can be applied to ports in CDM-Group 3 for Type 2 DM-RS. In yet another example, different CDM-Group specific phase shifts can be applied to ports in different frequency domain CDM groups for CSI-RS.

[0077] In one configuration, a technique is described for PAPR reduction in DMRS wherein CDM-Group specific unique PN sequences are generated using CDM-Group specific initialization values. In one example, the CDM-Group specific PN sequences can be used to map sequence values to ports within each CDM Group for both DMRS Type 1 and Type 2. In another example, the CDM group specific PN sequence initialization values for Type 1 and Type 2 DMRS can be implicitly derived from the DCI indicated values of the binary scrambling ID (ⁿsc_{; D}

)·

[0078] In one example, the new sequences can be used only when DCI formats 0 1 and 1 1 with CRC scrambled by C-RNTI, CS-RNTI and MCS-C-RNTI are used. In another example, for DMRS Type 2, RRC can configure two sets each containing two 16 bit Nm s. In yet another example, for CDM-groups 0 and 1, the two N_iD from the first set can be used while for CDM-Group 2, one of the two N_ID from the second set can be used. In a further example, the choice of N_ID for CDM-Group 2 from the second RRC configured N _r: set can be dynamically indicated by the n_SCJD bit DCI format l_l for DL or 0_l for UL with CRC scrambled by C-RNTI, CS-RNTI or MCS-C-RNTI. In yet a further example, the choice of using new techniques described herein or using Release- 15 techniques may be configurable to the UE and can be configured by an RRC parameter.

[0079] Another example provides functionality 700 of a user equipment (UE) operable to generate a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), as shown in FIG. 7. The UE can comprise one or more processors configured to map, at the UE, complex pseudo noise (PN) sequence symbols to one or more code-division-multiplexed (CDM)-Groups, as in block 710. The UE can comprise one or more processors configured to perform, on each CDM-Group of the one or more CDM-Groups, a CDM-Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the DM-RS having the reduced PAPR, as in block 720. The UE can comprise one or more processors configured to encode, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB), as in block 730. In addition, the UE can comprise a memory interface configured to send to a memory the mapped complex PN sequence symbols.

[0080] Another example provides functionality 800 of a Next Generation NodeB (gNB) operable to generate a downlink reference signal having a reduced peak-to-average power ratio (PAPR), as shown in FIG. 8. The gNB can comprise one or more processors configured to map, at the gNB, complex pseudo noise (PN) sequence symbols to one or more code-division-multiplexed (CDM)-Groups, as in block 810. The gNB can comprise one or more processors configured to perform, on each CDM-Group of the one or more CDM-Groups, a CDM-Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the downlink reference signal having the reduced PAPR, as in block 820. The gNB can comprise one or more processors configured to encode, at the gNB, the downlink reference signal having the reduced PAPR for transmission to a user equipment (UE), as in block 830. In addition, the gNB can comprise a memory interface configured to retrieve from a memory the mapped complex PN sequence symbols.

[0081] Another example provides at least one machine readable storage medium having instructions 900 embodied thereon for generating a demodulation reference signal (DM- RS) having a reduced peak-to-average power ratio (PAPR), as shown in FIG. 6. The instructions can be executed on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The instructions when executed by one or more processors of a user equipment (UE) perform: identifying, at the UE, one or more code-division-multiplexed (CDM)-Group specific initialization values, as in block 910. The instructions when executed by the one or more processors perform: generating, at the UE, CDM-Group specific unique pseudo noise (PN) sequences using the one or more CDM-Group specific initialization values, as in block 920. The instructions when executed by the one or more processors perform: generating, at the UE, the DM-RS having the reduced PAPR using the CDM-Group specific unique PN sequences, as in block 930. The instructions when executed by the one or more processors perform: encoding, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB), as in block 940.

[0082] FIG. 10 illustrates an architecture of a system 1000 of a network in accordance with some embodiments. The system 1000 is shown to include a user equipment (UE) 1001 and a UE 1002. The UEs 1001 and 1002 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

[0083] In some embodiments, any of the UEs 1001 and 1002 can comprise an Internet of Things (IoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network

(PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network.

[0084] The UEs 1001 and 1002 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 1010— the RAN 1010 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), aNextGen RAN (NG RAN), or some other type of RAN. The UEs 1001 and 1002 utilize connections 1003 and 1004, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 1003 and 1004 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

[0085] In this embodiment, the UEs 1001 and 1002 may further directly exchange communication data via a ProSe interface 1005. The ProSe interface 1005 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

[0086] The UE 1002 is shown to be configured to access an access point (AP) 1006 via connection 1007. The connection 1007 can comprise a local wireless connection, such as a connection consistent with any IEEE 1102.15 protocol, wherein the AP 1006 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 1006 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0087] The RAN 1010 can include one or more access nodes that enable the connections 1003 and 1004. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 1010 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 1011, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 1012.

[0088] Any of the RAN nodes 1011 and 1012 can terminate the air interface protocol and can be the first point of contact for the UEs 1001 and 1002. In some embodiments, any of the RAN nodes 1011 and 1012 can fulfill various logical functions for the RAN 1010 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[0089] In accordance with some embodiments, the UEs 1001 and 1002 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 1011 and 1012 over a multicarrier communication channel in accordance various communication techniques, such as, but not limited to, an Orthogonal Frequency-Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

[0090] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 1011 and 1012 to the UEs 1001 and 1002, while uplink transmissions can utilize similar techniques. The grid can be a time- frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane

representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time- frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

[0091] The physical downlink shared channel (PDSCH) may carry user data and higher- layer signaling to the UEs 1001 and 1002. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 1001 and 1002 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 1002 within a cell) may be performed at any of the RAN nodes 1011 and 1012 based on channel quality information fed back from any of the UEs 1001 and 1002. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 1001 and 1002.

[0092] The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex- valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=l, 2,

4, or 11).

[0093] Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[0094] The RAN 1010 is shown to be communicatively coupled to a core network (CN) 1020— via an Sl interface 1013. In embodiments, the CN 1020 may be an evolved packet core (EPC) network, aNextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the Sl interface 1013 is split into two parts: the Sl-U interface 1014, which carries traffic data between the RAN nodes 1011 and 1012 and the serving gateway (S-GW) 1022, and the Sl-mobility management entity (MME) interface 1015, which is a signaling interface between the RAN nodes 1011 and 1012 and MMEs 1021.

[0095] In this embodiment, the CN 1020 comprises the MMEs 1021, the S-GW 1022, the Packet Data Network (PDN) Gateway (P-GW) 1023, and a home subscriber server (HSS) 1024. The MMEs 1021 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 1021 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 1024 may comprise a database for network users, including subscription-related information to support the network entities’ handling of

communication sessions. The CN 1020 may comprise one or several HSSs 1024, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 1024 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[0096] The S-GW 1022 may terminate the Sl interface 1013 towards the RAN 1010, and routes data packets between the RAN 1010 and the CN 1020. In addition, the S-GW 1022 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

[0097] The P-GW 1023 may terminate an SGi interface toward a PDN. The P-GW 1023 may route data packets between the EPC network 1023 and external networks such as a network including the application server 1030 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 1025. Generally, the application server 1030 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 1023 is shown to be communicatively coupled to an application server 1030 via an IP communications interface 1025. The application server 1030 can also be configured to support one or more communication services (e.g., Voice over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 1001 and 1002 via the CN 1020.

[0098] The P-GW 1023 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 1026 is the policy and charging control element of the CN 1020. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE’s Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE’s IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 1026 may be communicatively coupled to the application server 1030 via the P-GW 1023. The application server 1030 may signal the PCRF 1026 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 1026 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 1030.

[0099] FIG. 11 illustrates example components of a device 1100 in accordance with some embodiments. In some embodiments, the device 1100 may include application circuitry 1102, baseband circuitry 1104, Radio Frequency (RF) circuitry 1106, front-end module (FEM) circuitry 1108, one or more antennas 1110, and power management circuitry (PMC) 1112 coupled together at least as shown. The components of the illustrated device 1100 may be included in a UE or a RAN node. In some embodiments, the device 1100 may include less elements (e.g., a RAN node may not utilize application circuitry 1102, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 1100 may include additional elements such as, for example, memory /storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations).

[00100] The application circuitry 1102 may include one or more application processors. For example, the application circuitry 1102 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory /storage and may be configured to execute instructions stored in the memory /storage to enable various applications or operating systems to run on the device 1100. In some embodiments, processors of application circuitry 1102 may process IP data packets received from an EPC.

[00101] The baseband circuitry 1104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1104 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 1106 and to generate baseband signals for a transmit signal path of the RF circuitry 1106. Baseband processing circuity 1104 may interface with the application circuitry 1102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1106. For example, in some embodiments, the baseband circuitry 1104 may include a third generation (3G) baseband processor 1104a, a fourth generation (4G) baseband processor H04b, a fifth generation (5G) baseband processor H04c, or other baseband processor(s) H04d for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 1104 (e.g., one or more of baseband processors H04a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1106. In other embodiments, some or all of the functionality of baseband processors H04a-d may be included in modules stored in the memory H04g and executed via a Central Processing Unit (CPU) H04e. The radio control

functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments,

modulation/demodulation circuitry of the baseband circuitry 1104 may include Fast- Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 1104 may include convolution, tail-biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[00102] In some embodiments, the baseband circuitry 1104 may include one or more audio digital signal processor(s) (DSP) ll04f. The audio DSP(s) H04f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 1104 and the application circuitry 1102 may be implemented together such as, for example, on a system on a chip (SOC).

[00103] In some embodiments, the baseband circuitry 1104 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 1104 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 1104 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[00104] RF circuitry 1106 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 1106 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1106 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1108 and provide baseband signals to the baseband circuitry 1104. RF circuitry 1106 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1104 and provide RF output signals to the FEM circuitry 1108 for transmission.

[00105] In some embodiments, the receive signal path of the RF circuitry 1106 may include mixer circuitry 1106a, amplifier circuitry 1106b and filter circuitry 1106c. In some embodiments, the transmit signal path of the RF circuitry 1106 may include filter circuitry 1106c and mixer circuitry 1106a. RF circuitry 1106 may also include synthesizer circuitry H06d for synthesizing a frequency for use by the mixer circuitry 1106a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 1106a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1108 based on the synthesized frequency provided by synthesizer circuitry H06d. The amplifier circuitry 1106b may be configured to amplify the down-converted signals and the filter circuitry 1106c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 1104 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 1106a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[00106] In some embodiments, the mixer circuitry 1106a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry H06d to generate RF output signals for the FEM circuitry 1108. The baseband signals may be provided by the baseband circuitry 1104 and may be filtered by filter circuitry 1106c.

[00107] In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may be configured for super-heterodyne operation.

[00108] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 1106 may include analog-to-digital converter (ADC) and digital -to-analog converter (DAC) circuitry and the baseband circuitry 1104 may include a digital baseband interface to communicate with the RF circuitry 1106.

[00109] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the

embodiments is not limited in this respect.

[00110] In some embodiments, the synthesizer circuitry H06d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry H06d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[00111] The synthesizer circuitry H06d may be configured to synthesize an output frequency for use by the mixer circuitry 1106a of the RF circuitry 1106 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry H06d may be a fractional N/N+l synthesizer.

[00112] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 1104 or the applications processor 1102 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1102.

[00113] Synthesizer circuitry H06d of the RF circuitry 1106 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[00114] In some embodiments, synthesizer circuitry H06d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 1106 may include an IQ/polar converter.

[00115] FEM circuitry 1108 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1110, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1106 for further processing. FEM circuitry 1108 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1106 for transmission by one or more of the one or more antennas 1110. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 1106, solely in the FEM 1108, or in both the RF circuitry 1106 and the FEM 1108.

[00116] In some embodiments, the FEM circuitry 1108 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNAto amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 1106). The transmit signal path of the FEM circuitry 1108 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1110).

[00117] In some embodiments, the PMC 1112 may manage power provided to the baseband circuitry 1104. In particular, the PMC 1112 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 1112 may often be included when the device 1100 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 1112 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation

characteristics.

[00118] While FIG. 11 shows the PMC 1112 coupled only with the baseband circuitry 1104. However, in other embodiments, the PMC 11 12 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 1102, RF circuitry 1106, or FEM 1108.

[00119] In some embodiments, the PMC 1112 may control, or otherwise be part of, various power saving mechanisms of the device 1100. For example, if the device 1100 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 1100 may power down for brief intervals of time and thus save power.

[00120] If there is no data traffic activity for an extended period of time, then the device 1100 may transition off to an RRC Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 1100 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 1100 may not receive data in this state, in order to receive data, it must transition back to RRC Connected state.

[00121] An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

[00122] Processors of the application circuitry 1102 and processors of the baseband circuitry 1104 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 1104, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 1104 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

[00123] FIG. 12 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 1104 of FIG. 11 may comprise processors H04a-ll04e and a memory H04g utilized by said processors. Each of the processors H04a-ll04e may include a memory interface, l204a-l204e, respectively, to send/receive data to/from the memory H04g.

[00124] The baseband circuitry 1104 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 1212 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 1104), an application circuitry interface 1214 (e.g., an interface to send/receive data to/from the application circuitry 1102 of FIG. 11), an RF circuitry interface 1216 (e.g., an interface to send/receive data to/from RF circuitry 1106 of FIG. 11), a wireless hardware connectivity interface 1218 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface 1220 (e.g., an interface to send/receive power or control signals to/from the PMC 1112.

[00125] FIG. 13 provides an example illustration of the wireless device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile

communication device, a tablet, a handset, or other type of wireless device. The wireless device can include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or, transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband processing unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), or other type of wireless wide area network (WWAN) access point. The wireless device can be configured to communicate using at least one wireless communication standard such as, but not limited to, 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The wireless device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The wireless device can communicate in a wireless local area network

(WLAN), a wireless personal area network (WPAN), and/or a WWAN. The wireless device can also comprise a wireless modem. The wireless modem can comprise, for example, a wireless radio transceiver and baseband circuitry (e.g., a baseband processor). The wireless modem can, in one example, modulate signals that the wireless device transmits via the one or more antennas and demodulate signals that the wireless device receives via the one or more antennas.

[00126] FIG. 13 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the wireless device. The display screen can be a liquid crystal display (LCD) screen, or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or another type of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. Anon-volatile memory port can also be used to provide data input/output options to a user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. A keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

Examples

[00127] The following examples pertain to specific technology embodiments and point out specific features, elements, or actions that can be used or otherwise combined in achieving such embodiments.

[00128] Example 1 includes an apparatus of a user equipment (UE) operable to generate a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the apparatus comprising: one or more processors configured to: map, at the UE, complex pseudo noise (PN) sequence symbols to one or more code division-multiplexed (CDM)-Groups; perform, on each CDM-Group of the one or more CDM-Groups, a CDM-Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the DM-RS having the reduced PAPR; and encode, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB), wherein the DM-RS is transmitted in a physical uplink shared channel (PUSCH) using a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) symbol; and a memory interface configured to send to a memory the mapped complex PN sequence symbols.

[00129] Example 2 includes the apparatus of Example 1, further comprising a transceiver configured to transmit the DM-RS to the gNB.

[00130] Example 3 includes the apparatus of any of Examples 1 to 2, wherein the one or more processors are further configured to: map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ; and map complex conjugates of the original sequence values to ports in a CDM-Group 2 to generate a Type 1 DM-RS.

[00131] Example 4 includes the apparatus of any of Examples 1 to 3, wherein the one or more processors are further configured to: map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ; map complex conjugates of the original sequence values to ports in a CDM-Group 2; and map phase- shifted sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 3 to generate a Type 2 DM-RS.

[00132] Example 5 includes the apparatus of any of Examples 1 to 4, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 to generate a Type 1 DM-RS.

[00133] Example 6 includes the apparatus of any of Examples 1 to 5, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 and apply a different CDM-Group specific phase shift to ports in a CDM-Group 3, to generate a Type 2 DM-RS.

[00134] Example 7 includes an apparatus of a Next Generation NodeB (gNB) operable to generate a downlink reference signal having a reduced peak-to-average power ratio (PAPR), the apparatus comprising: one or more processors configured to: map, at the gNB, complex pseudo noise (PN) sequence symbols to one or more code-division- multiplexed (CDM)-Groups; perform, on each CDM-Group of the one or more CDM- Groups, a CDM-Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the downlink reference signal having the reduced PAPR; and encode, at the gNB, the downlink reference signal having the reduced PAPR for transmission to a user equipment (UE) over a physical downlink shared channel (PDSCH); and a memory interface configured to retrieve from a memory the mapped complex PN sequence symbols.

[00135] Example 8 includes the apparatus of Example 7, further comprising a transceiver configured to transmit the downlink reference signal to the UE.

[00136] Example 9 includes the apparatus of any of Examples 7 to 8, wherein the downlink reference signal is a demodulation reference signal (DM-RS) or a channel state information reference signal (CSI-RS).

[00137] Example 10 includes the apparatus of any of Examples 7 to 9, wherein the one or more processors are further configured to: map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ; and map complex conjugates of the original sequence values to ports in a CDM-Group 2 to generate the downlink reference signal, wherein the downlink reference signal is a Type 1 demodulation reference signal (DM-RS).

[00138] Example 11 includes the apparatus of any of Examples 7 to 10, wherein the one or more processors are further configured to: map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ; map complex conjugates of the original sequence values to ports in a CDM-Group 2; and map phase- shifted sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 3 to generate the downlink reference signal, wherein the downlink reference signal is a Type 2 demodulation reference signal (DM-RS).

[00139] Example 12 includes the apparatus of any of Examples 7 to 11, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 to generate the downlink reference signal, wherein the downlink reference signal is a Type 1 demodulation reference signal (DM-RS).

[00140] Example 13 includes the apparatus of any of Examples 7 to 12, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 and apply a different CDM-Group specific phase shift to ports in a CDM-Group 3 to generate the downlink reference signal, wherein the downlink reference signal is a Type 2 demodulation reference signal (DM- RS).

[00141] Example 14 includes the apparatus of any of Examples 7 to 13, wherein the one or more processors are further configured to: apply different CDM-Group specific phase shifts to ports in different frequency domain CDM groups to generate the downlink reference signal, wherein the downlink reference signal is a channel state information reference signal (CSI-RS).

[00142] Example 15 includes at least one machine readable storage medium having instructions embodied thereon for generating a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the instructions when executed by one or more processors at a user equipment (UE) perform the following: identifying, at the UE, one or more code-division-multiplexed (CDM)-Group specific initialization values; generating, at the UE, CDM-Group specific unique pseudo noise (PN) sequences using the one or more CDM-Group specific initialization values; generating, at the UE, the DM-RS having the reduced PAPR using the CDM-Group specific unique PN sequences; and encoding, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB).

[00143] Example 16 includes the at least one machine readable storage medium of Example 15, further comprising instructions when executed perform the following: mapping sequence values to ports within each CDM Group for DM-RS Type 1 and DM- RS Type 2 using the CDM-Group specific unique PN sequences.

[00144] Example 17 includes the at least one machine readable storage medium of any of Examples 15 to 16, further comprising instructions when executed perform the following: determining the CDM-Group specific initialization values for the CDM-Group specific unique PN sequences for DM-RS Type 1 and DM-RS Type 2 using downlink control information (DCI) indicated values of a binary scrambling identifier (ID).

[00145] Example 18 includes the at least one machine readable storage medium of any of Examples 15 to 17, further comprising instructions when executed perform the following: using the CDM-Group specific unique PN sequences when downlink control information (DCI) formats 0 1 and 1 1 with cyclic redundancy check (CRC) scrambled by a cell radio network temporary identifier (C-RNTI), a configured scheduling cell radio network temporary identifier (CS-RNTI), or a modulation coding scheme cell radio network temporary identifier (MCS-C-RNTI) is used.

[00146] Example 19 includes the at least one machine readable storage medium of any of Examples 15 to 18, further comprising instructions when executed perform the following: decoding a radio resource control (RRC) configuration parameter received from the gNB for generating a low PAPR reference signal; and generating the DM-RS using the RRC configuration parameter.

[00147] Example 20 includes the at least one machine readable storage medium of any of Examples 15 to 19, wherein the DM-RS is a user specific reference signal used for channel estimation for physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) data demodulation.

[00148] Example 21 includes at least one machine readable storage medium having instructions embodied thereon for generating a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the instructions when executed by one or more processors at a Next Generation NodeB (gNB) perform the following: identifying, at the gNB, one or more code-division-multiplexed (CDM)-Group specific initialization values; generating, at the gNB, CDM-Group specific unique pseudo noise (PN) sequences using the one or more CDM-Group specific initialization values;

generating, at the gNB, the DM-RS having the reduced PAPR using the CDM-Group specific unique PN sequences; and encoding, at the gNB, the DM-RS having the reduced PAPR for transmission to a user equipment (UE).

[00149] Example 22 includes the at least one machine readable storage medium of Example 21, further comprising instructions when executed perform the following: mapping sequence values to ports within each CDM Group for DM-RS Type 1 and DM- RS Type 2 using the CDM-Group specific unique PN sequences.

[00150] Example 23 includes the at least one machine readable storage medium of any of Examples 21 to 22, further comprising instructions when executed perform the following: determining the CDM-Group specific initialization values for the CDM-Group specific unique PN sequences for DM-RS Type 1 and DM-RS Type 2 using downlink control information (DCI) indicated values of a binary scrambling identifier (ID).

[00151] Example 24 includes the at least one machine readable storage medium of any of Examples 21 to 23, further comprising instructions when executed perform the following: using the CDM-Group specific unique PN sequences when downlink control information (DCI) formats 0 1 and 1 1 with cyclic redundancy check (CRC) scrambled by a cell radio network temporary identifier (C-RNTI), a configured scheduling cell radio network temporary identifier (CS-RNTI), or a modulation coding scheme cell radio network temporary identifier (MCS-C-RNTI) is used.

[00152] Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, compact disc-read-only memory (CD-ROMs), hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and non volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a random-access memory (RAM), erasable programmable read only memory (EPROM), flash drive, optical drive, magnetic hard drive, solid state drive, or other medium for storing electronic data. The node and wireless device may also include a transceiver module (i.e., transceiver), a counter module (i.e., counter), a processing module (i.e., processor), and/or a clock module (i.e., clock) or timer module (i.e., timer). In one example, selected components of the transceiver module can be located in a cloud radio access network (C-RAN). One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.

[00153] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

[00154] It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very -large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[00155] Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module may not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

[00156] Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The modules may be passive or active, including agents operable to perform desired functions.

[00157] Reference throughout this specification to "an example" or“exemplary” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in an example" or the word“exemplary” in various places throughout this specification are not necessarily all referring to the same embodiment.

[00158] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present technology may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present technology.

[00159] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of embodiments of the technology. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[00160] While the forgoing examples are illustrative of the principles of the present technology in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the technology.

Claims

CLAIMS What is claimed is:

1. An apparatus of a user equipment (UE) operable to generate a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the apparatus comprising:

one or more processors configured to:

map, at the UE, complex pseudo noise (PN) sequence symbols to one or more code-division-multiplexed (CDM)-Groups;

perform, on each CDM-Group of the one or more CDM-Groups, a CDM- Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the DM-RS having the reduced PAPR; and

encode, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB), wherein the DM-RS is transmitted in a physical uplink shared channel (PUSCH) using a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) symbol; and

a memory interface configured to send to a memory the mapped complex PN sequence symbols.

2. The apparatus of claim 1, further comprising a transceiver configured to transmit the DM-RS to the gNB.

3. The apparatus of claim 1, wherein the one or more processors are further configured to:

map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1; and

map complex conjugates of the original sequence values to ports in a CDM-Group 2 to generate a Type 1 DM-RS.

4. The apparatus of any of claims 1 to 3, wherein the one or more processors are further configured to: map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ;

map complex conjugates of the original sequence values to ports in a CDM-Group 2; and

map phase-shifted sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 3 to generate a Type 2 DM-RS.

5. The apparatus of any of claims 1 to 3, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 to generate a Type 1 DM-RS.

6. The apparatus of any of claims 1 to 3, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 and apply a different CDM-Group specific phase shift to ports in a CDM-Group 3, to generate a Type 2 DM-RS.

7. An apparatus of a Next Generation NodeB (gNB) operable to generate a downlink reference signal having a reduced peak-to-average power ratio (PAPR), the apparatus comprising:

one or more processors configured to:

map, at the gNB, complex pseudo noise (PN) sequence symbols to one or more code-division-multiplexed (CDM)-Groups;

perform, on each CDM-Group of the one or more CDM-Groups, a CDM- Group specific linear or non-linear operation on the complex PN sequence symbols mapped to the one or more CDM-Groups, to generate the downlink reference signal having the reduced PAPR; and

encode, at the gNB, the downlink reference signal having the reduced PAPR for transmission to a user equipment (UE) over a physical downlink shared channel (PDSCH); and

a memory interface configured to retrieve from a memory the mapped complex PN sequence symbols.

8. The apparatus of claim 7, further comprising a transceiver configured to transmit the downlink reference signal to the UE.

9. The apparatus of claim 7, wherein the downlink reference signal is a

demodulation reference signal (DM-RS) or a channel state information reference signal (CSI-RS).

10. The apparatus of any of claims 7 to 9, wherein the one or more processors are further configured to:

map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1; and

map complex conjugates of the original sequence values to ports in a CDM-Group 2 to generate the downlink reference signal, wherein the downlink reference signal is a Type 1 demodulation reference signal (DM- RS).

11. The apparatus of any of claims 7 to 9, wherein the one or more processors are further configured to:

map original sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 1 ;

map complex conjugates of the original sequence values to ports in a CDM-Group 2; and

map phase-shifted sequence values associated with the complex PN sequence symbols to ports in a CDM-Group 3 to generate the downlink reference signal, wherein the downlink reference signal is a Type 2 demodulation reference signal (DM-RS).

12. The apparatus of any of claims 7 to 9, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 to generate the downlink reference signal, wherein the downlink reference signal is a Type 1 demodulation reference signal (DM-RS).

13. The apparatus of any of claims 7 to 9, wherein the one or more processors are further configured to: apply CDM-Group specific shifts to sequence values mapped to ports in a CDM-Group 2 and apply a different CDM-Group specific phase shift to ports in a CDM-Group 3 to generate the downlink reference signal, wherein the downlink reference signal is a Type 2 demodulation reference signal (DM-RS).

14. The apparatus of claim 7, wherein the one or more processors are further configured to: apply different CDM-Group specific phase shifts to ports in different frequency domain CDM groups to generate the downlink reference signal, wherein the downlink reference signal is a channel state information reference signal (CSI-RS).

15. At least one machine readable storage medium having instructions embodied thereon for generating a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the instructions when executed by one or more processors at a user equipment (UE) perform the following: identifying, at the UE, one or more code-division-multiplexed (CDM)- Group specific initialization values;

generating, at the UE, CDM-Group specific unique pseudo noise (PN) sequences using the one or more CDM-Group specific initialization values; generating, at the UE, the DM-RS having the reduced PAPR using the CDM-Group specific unique PN sequences; and

encoding, at the UE, the DM-RS having the reduced PAPR for transmission to a Next Generation NodeB (gNB).

16. The at least one machine readable storage medium of claim 15, further

comprising instructions when executed perform the following: mapping sequence values to ports within each CDM Group for DM-RS Type 1 and DM-RS Type 2 using the CDM-Group specific unique PN sequences.

17. The at least one machine readable storage medium of claim 15, further comprising instructions when executed perform the following: determining the CDM-Group specific initialization values for the CDM-Group specific unique PN sequences for DM-RS Type 1 and DM-RS Type 2 using downlink control information (DCI) indicated values of a binary scrambling identifier (ID).

18. The at least one machine readable storage medium of any of claims 15 to 17, further comprising instructions when executed perform the following: using the CDM-Group specific unique PN sequences when downlink control information (DCI) formats 0 1 and 1 1 with cyclic redundancy check (CRC) scrambled by a cell radio network temporary identifier (C-RNTI), a configured scheduling cell radio network temporary identifier (CS-RNTI), or a modulation coding scheme cell radio network temporary identifier (MCS-C- RNTI) is used.

19. The at least one machine readable storage medium of any of claims 15 to 17, further comprising instructions when executed perform the following:

decoding a radio resource control (RRC) configuration parameter received from the gNB for generating a low PAPR reference signal; and

generating the DM-RS using the RRC configuration parameter.

20. The at least one machine readable storage medium of any of claims 15 to 17, wherein the DM-RS is a user specific reference signal used for channel estimation for physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) data demodulation.

21. At least one machine readable storage medium having instructions embodied thereon for generating a demodulation reference signal (DM-RS) having a reduced peak-to-average power ratio (PAPR), the instructions when executed by one or more processors at a Next Generation NodeB (gNB) perform the following: identifying, at the gNB, one or more code-division-multiplexed (CDM)- Group specific initialization values;

generating, at the gNB, CDM-Group specific unique pseudo noise (PN) sequences using the one or more CDM-Group specific initialization values; generating, at the gNB, the DM-RS having the reduced PAPR using the CDM-Group specific unique PN sequences; and

encoding, at the gNB, the DM-RS having the reduced PAPR for transmission to a user equipment (UE).

22. The at least one machine readable storage medium of claim 21, further

comprising instructions when executed perform the following: mapping sequence values to ports within each CDM Group for DM-RS Type 1 and DM-RS Type 2 using the CDM-Group specific unique PN sequences.

23. The at least one machine readable storage medium of claim 21, further

comprising instructions when executed perform the following: determining the CDM-Group specific initialization values for the CDM-Group specific unique PN sequences for DM-RS Type 1 and DM-RS Type 2 using downlink control information (DCI) indicated values of a binary scrambling identifier (ID).

24. The at least one machine readable storage medium of any of claims 21 to 23, further comprising instructions when executed perform the following: using the CDM-Group specific unique PN sequences when downlink control information (DCI) formats 0 1 and 1 1 with cyclic redundancy check (CRC) scrambled by a cell radio network temporary identifier (C-RNTI), a configured scheduling cell radio network temporary identifier (CS-RNTI), or a modulation coding scheme cell radio network temporary identifier (MCS-C- RNTI) is used.