Patent Description:
Wireless communications networks may operate using millimeter wave (mmW) spectrum that may be associated with greater path loss for transmitted signals. In such cases, beamforming may be used to increase the strength of wireless signals, including signals that are broadcast from a base station and used by a UE. However, various transmission configurations may affect power ratios associated with certain signals, and it may be desirable to implement techniques related to such signals.

<NPL>discloses avoiding a high MPR due to increased cubic metric in a contiguous carrier aggregation case. <NPL> discloses different aspects of the synchronization in a mmwave system. <NPL>discloses controlling CM for downlink transmissions by applying different phase offsets to different component carriers. <NPL> discloses comparing different multiplexing methids to transmit sync signals within a SS block. <NPL> discloses different aspects of synchronization in a mmwave system.

A method performed by a base station and a base station are defined by the appended independent claims <NUM>, <NUM> respectively.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying the set of phase offsets based at least in part on a number of component carriers of a set of component carriers, or a sequence of synchronization signals associated with different component carriers of the set of component carriers, or both. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying a PAPR or a cubic metric (CM) associated with the set of phase offsets, wherein identifying the set of phase offsets may be based at least in part on minimizing the identified PAPR or the identified CM.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying a PAPR or a CM associated with the set of phase offsets, wherein identifying the set of phase offsets may be based at least in part on whether the identified PAPR or the identified CM may be less than a predetermined threshold. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting one or more sequences for the set of synchronization signals. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the one or more sequences comprise a Zadoff-Chu sequence, or a M sequence, or a combination thereof.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, selecting the one or more sequences comprises: selecting one or more combinations of a root and a cyclic shift of a Zadoff-Chu sequence that minimizes a PAPR or a CM. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting one or more combinations of a polynomial and a cyclic shift of a M sequence that minimized the PAPR or the CM.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, selecting the one or more sequences comprises: selecting one or more combinations of a root and a cyclic shift of a Zadoff-Chu sequence that corresponds to a PAPR value or a CM value that may be below a predetermined threshold. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting one or more combinations of a polynomial and a cyclic shift of an M sequence that corresponds to a PAPR value or a CM value that may be below a predetermined threshold.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for transmitting a synchronization signal block using the selected phase offsets, wherein the synchronization signal block comprises at least one or more of a PSS, an SSS, a physical broadcast channel (PBCH), and a demodulation reference signal (DMRS) of the PBCH.

A method of wireless communication is described. The method may include identifying a set of synchronization signal blocks and transmitting each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier.

An apparatus for wireless communication is described. The apparatus may include means for identifying a set of synchronization signal blocks and means for transmitting each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier.

Another apparatus for wireless communication is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to identify a set of synchronization signal blocks and transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier.

A non-transitory computer readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to identify a set of synchronization signal blocks and transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting each synchronization signal block comprises: transmitting each synchronization signal block using a different antenna port of the base station or using a same antenna port of the base station. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for generating a synchronization signal block corresponding to the different antenna port. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for transmitting the synchronization signal block in a different component carrier of the set of component carriers from the different antenna port.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting each synchronization signal block on the one or more component carriers comprises: transmitting each synchronization signal block on different component carriers of the set of component carriers, each synchronization signal block associated with a different component carrier of the set of component carriers.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting each synchronization signal block comprises: transmitting each synchronization signal block using a first beam configuration having a first width greater than a second width of a second beam configuration, the second beam configuration associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first beam configuration may be based at least in part on a plurality of beam directions. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying a first transmit power greater than a second transmit power, the second transmit power associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port, wherein transmitting each synchronization signal block in the one or more component carriers of the set of component carriers includes using the first transmit power.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, each synchronization signal block comprises at least one or more of a PSS, an SSS, a PBCH, and a DMRS of the PBCH. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying an indication of an antenna port associated with different component carriers, or a selected transmission beam, or both, wherein transmitting the synchronization signal block comprises transmitting the indication. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting each synchronization signal block comprises: refraining from transmitting another signal while transmitting each synchronization signal block.

Some wireless communication systems may operate in millimeter wave (mmW) frequency ranges, e.g., <NUM>, <NUM>, <NUM>, etc. Wireless communication at these frequencies may be associated with increased signal attenuation (e.g., path loss), which may be influenced by various factors, such as temperature, barometric pressure, diffraction, etc. As a result, signal processing techniques, such as beamforming, may be used to coherently combine energy and overcome the path losses at these frequencies.

The transmission of synchronization signals and synchronization signal blocks by a base station (e.g., including primary synchronization signals (PSSs), secondary synchronization signals (SSSs), and physical broadcast channels (PBCHs)) may be utilized by a user equipment (UE) to synchronize its timing with the base station. Additionally, in wireless communications systems using mmW frequency ranges, synchronization signals may utilize beamforming techniques to meet a link budget. In such cases, a base station may use several antenna ports (e.g., <NUM>, <NUM>, <NUM>, <NUM> antenna ports) connected to subarrays of antennas to form beams in various directions using a number of analog weight factors, and synchronization signals associated with the antenna ports may be transmitted in different directions. That is, the base station may sweep beams in multiple directions, where the synchronization signal may be transmitted for a relatively short duration in each direction.

Synchronization signals may be transmitted by a base station using time division multiplexing (TDM) or frequency division multiplexing (FDM), although TDM may, in some cases, be associated with a reduced peak-to-average power ratio (PAPR) of synchronization signals, such as PSSs. In some cases, if the PSS is transmitted using multiple component carriers (such as with the simultaneous transmission of PSS in multiple directions from different antenna ports) the reduction of PAPR for synchronization signals may not be maintained through the use of TDM alone. Accordingly, there may be techniques in which signals may be transmitted using TDM or FDM that reduce the PAPR (or cubic metric (CM)) of synchronization signals.

In some examples, a base station may use a selected set of phase offsets for the transmission of synchronization signals (e.g., PSSs) that are simultaneously transmitted using FDM, where a different phase offset may be applied to one or more synchronization signals transmitted on one or more component carriers. That is, a first synchronization signal transmitted in a first component carrier is phase shifted (e.g., using a first phase offset) relative to a second synchronization signal transmitted in a second component carrier (e.g., using a second phase offset). The synchronization signal may then be transmitted during a symbol period on the one or more component carriers. For example, the synchronization signals is transmitted on different component carriers. In an unclaimed alternative, a base station may transmit a synchronization signal of a set of synchronization signals using only one component carrier for each transmit antenna port. For instance, PSSs from different antenna ports may be transmitted on different respective component carriers. The application of the phase offsets to PSSs transmitted over a set of component carriers and transmitting PSSs from different antenna ports on one or more component carriers may reduce the PAPR of the transmitted signal and provide other benefits. In some examples, synchronization signal blocks may be transmitted on the one or more component carries, or may be transmitted simultaneously on a wideband carrier. In such cases, the synchronization signal blocks may be transmitted using a same or different antenna port of the base station.

Aspects of the disclosure are initially described in the context of a wireless communications system. Further examples are then provided of synchronization signal transmission schemes. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to synchronization signal transmission techniques for PAPR reduction.

<FIG> illustrates an example of a wireless communications system <NUM> in accordance with various aspects of the present disclosure. The wireless communications system <NUM> includes base stations <NUM>, UEs <NUM>, and a core network <NUM>. In some examples, the wireless communications system <NUM> may be a LTE (or LTE-Advanced) network, or a New Radio (NR) network. In some cases, wireless communications system <NUM> may support enhanced broadband communications, ultra-reliable (i.e., mission critical) communications, low latency communications, and communications with low-cost and low-complexity devices. Wireless communications system <NUM> may be an example of a system that enables a sustained PAPR reduction when transmitting synchronization signals.

Each base station <NUM> may provide communication coverage for a respective geographic coverage area <NUM>. Control information and data may be multiplexed on an uplink channel or downlink according to various techniques. Control information and data may be multiplexed on a downlink channel, for example, using TDM techniques, FDM techniques, or hybrid TDM-FDM techniques. In some examples, the control information transmitted during a transmission time interval (TTI) of a downlink channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region and one or more UE-specific control regions).

A UE <NUM> may also be referred to as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may also be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a personal electronic device, a handheld device, a personal computer, a wireless local loop (WLL) station, an Internet of things (IoT) device, an Internet of Everything (IoE) device, a machine type communication (MTC) device, an appliance, an automobile, or the like.

The core network may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW).

Wireless communications system <NUM> may operate in an ultra-high frequency (UHF) frequency region using frequency bands from <NUM> to <NUM> (<NUM>), although in some cases wireless local area networks (WLANs) may use frequencies as high as <NUM>. This region may also be known as the decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may propagate mainly by line of sight, and may be blocked by buildings and environmental features. However, the waves may penetrate walls sufficiently to provide service to UEs <NUM> located indoors. Transmission of UHF waves is characterized by smaller antennas and shorter range (e.g., less than <NUM>) compared to transmission using the smaller frequencies (and longer waves) of the high frequency (HF) or very high frequency (VHF) portion of the spectrum. In some cases, wireless communications system <NUM> may also utilize extremely high frequency (EHF) portions of the spectrum (e.g., from <NUM> to <NUM>). This region may also be known as the millimeter band, since the wavelengths range from approximately one millimeter to one centimeter in length. Thus, EHF antennas may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE <NUM> (e.g., for directional beamforming). However, EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than UHF transmissions.

Wireless communications system <NUM> may support millimeter wave (mmW) communications between UEs <NUM> and base stations <NUM>. Devices operating in mmW or EHF bands may have multiple antennas to allow beamforming. That is, a base station <NUM> may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM>. Beamforming (which may also be referred to as spatial filtering or directional transmission) is a signal processing technique that may be used at a transmitter (e.g. a base station <NUM>) to shape and/or steer an overall antenna beam in the direction of a target receiver (e.g. a UE <NUM>). This may be achieved by combining elements in an antenna array in such a way that transmitted signals at particular angles experience constructive interference while others experience destructive interference.

Multiple-input multiple-output (MIMO) wireless systems use a transmission scheme between a transmitter (e.g. a base station <NUM>) and a receiver (e.g. a UE <NUM>), where both transmitter and receiver are equipped with multiple antennas. Some portions of wireless communications system <NUM> may use beamforming. For example, base station <NUM> may have an antenna array with a number of rows and columns of antenna ports that the base station <NUM> may use for beamforming in its communication with UE <NUM>. Signals may be transmitted multiple times in different directions (e.g., each transmission may be beamformed differently). A mmW receiver (e.g., a UE <NUM>) may try multiple beams (e.g., antenna subarrays) while receiving the synchronization signals.

In some cases, the antennas of a base station <NUM> or UE <NUM> may be located within one or more antenna arrays, which may support beamforming or MIMO operation. One or more base station antennas or antenna arrays may be collocated at an antenna assembly, such as an antenna tower. A base station <NUM> may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM>.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit (which may be a sampling period of Ts = <NUM>/<NUM>,<NUM>,<NUM> seconds). Time resources may be organized according to radio frames of length of <NUM> (Tf = 307200Ts), which may be identified by a system frame number (SFN) ranging from <NUM> to <NUM>. Each frame may include ten <NUM> subframes numbered from <NUM> to <NUM>. A subframe may be further divided into two <NUM> slots, each of which contains <NUM> or <NUM> modulation symbol periods (depending on the length of the cyclic prefix prepended to each symbol). Excluding the cyclic prefix, each symbol contains <NUM> sample periods. In some cases the subframe may be the smallest scheduling unit, also known as a TTI. In other cases, a TTI may be shorter than a subframe or may be dynamically selected (e.g., in short TTI bursts or in selected component carriers using short TTIs).

Wireless communications system <NUM> may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier, a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink component carriers and one or more uplink component carriers for carrier aggregation. Carrier aggregation may be used with both frequency division duplexed (FDD) and time division duplexed (TDD) component carriers.

An eCC may be characterized by one or more features including: wider bandwidth, shorter symbol duration, shorter TTIs, and modified control channel configuration. An eCC may also be configured for use in unlicensed spectrum or shared spectrum (where more than one operator is allowed to use the spectrum). An eCC characterized by wide bandwidth may include one or more segments that may be utilized by UEs <NUM> that are not capable of monitoring the whole bandwidth or prefer to use a limited bandwidth (e.g., to conserve power).

A shorter symbol duration may be associated with increased subcarrier spacing. A TTI in an eCC may consist of one or multiple symbols. In some cases, the TTI duration (that is, the number of symbols in a TTI) may be variable. A shorter symbol duration is associated with increased subcarrier spacing. A device, such as a UE <NUM> or base station <NUM>, utilizing eCCs may transmit wideband signals (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) at reduced symbol durations (e.g., <NUM> microseconds). A TTI in eCC may consist of one or multiple symbols. In some cases, the TTI duration (that is, the number of symbols in a TTI) may be variable.

A UE <NUM> attempting to access a wireless network may perform an initial cell search by detecting a PSS from a base station <NUM>. The PSS may enable synchronization of slot timing and may indicate a physical layer identity value. The UE <NUM> may then receive an SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The SSS may also enable detection of a duplexing mode and a cyclic prefix length. Some systems, such as TDD systems, may transmit an SSS but not a PSS. Both the PSS and the SSS may be located in the central <NUM> and <NUM> subcarriers of a carrier, respectively. After receiving the PSS and SSS, the UE <NUM> may receive a master information block (MIB), which may be transmitted in the physical broadcast channel (PBCH). The MIB may contain system bandwidth information, a system frame number (SFN), and a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH) configuration. After decoding the MIB, the UE <NUM> may receive one or more system information blocks (SIBs). For example, SIB1 may contain cell access parameters and scheduling information for other SIBs. Decoding SIB1 may enable the UE <NUM> to receive SIB2. SIB2 may contain radio resource control (RRC) configuration information related to random access channel (RACH) procedures, paging, physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), power control, sounding reference signal (SRS), and cell barring.

In some examples, synchronization signals that are transmitted using beamforming may be used to identify a best transmission and reception beam pair that meets a certain link budget (such as with a RACH Message-<NUM>). In some cases, synchronization signals in the frequency domain may be limited to a minimum bandwidth. For example, synchronization signal transmissions may be associated with a bandwidth between <NUM> and <NUM>. Additionally, orthogonal frequency division multiplexing (OFDM) symbols used for synchronization signals may not be frequency division multiplexed with other signals, which may support a full transmission power by a base station.

Wireless communications system <NUM> may support the transmission of synchronization signals using a set of phase offsets that are simultaneously transmitted using FDM. The described techniques also provide for the transmission of synchronization signal blocks, where each synchronization signal block is transmitted on one or more component carriers or transmitted simultaneously on a wideband carrier. For example, a base station <NUM> may identify a set of synchronization signals (e.g., a set of PSSs) to be transmitted over one or more component carriers. In some cases, each PSS may be associated with a different component carrier, and the base station <NUM> may apply a different phase offset to each PSS when transmitting the set of PSSs on the different component carriers. In some examples, the base station <NUM> may transmit the synchronization signal blocks on the component carriers using a different antenna port for each component carrier.

<FIG> illustrates an example of a wireless communications system <NUM> for synchronization signal transmission techniques for PAPR reduction. Wireless communications system <NUM> may include a base station <NUM>-a and a UE <NUM>-a, which may be examples of the corresponding devices described with reference to <FIG>. Wireless communications system <NUM> may be an example of the transmission of PSS from base station <NUM>-a using a set of phase offsets. Additionally or alternatively, wireless communications system <NUM> may be an example of the transmission of PSS in one component carrier for each antenna port.

Wireless communications system <NUM> may be an example of a mmW communications system, and may accordingly use beamforming to overcome path loss within the system. The transmission of synchronization signals (e.g., PSSs, SSSs, PBCHs) from base station <NUM>-a may be used by UE <NUM>-a to synchronize its timing with base station <NUM>-a. For instance, base station <NUM>-a may use beams <NUM> to transmit synchronization signals in multiple directions, where different antenna ports of base station <NUM>-a are used to transmit in the different directions. Additionally, the synchronization signals transmitted by base station <NUM>-a may be swept through each direction, where the signals corresponding to different directions may be transmitted in different symbol periods (e.g., OFDM symbols). In some cases, base station <NUM>-a may also refrain from multiplexing data with a PSS.

Synchronization signals may be transmitted by base station <NUM>-a using TDM or FDM. However, if the PSS is transmitted using multiple component carriers, the reduction of PAPR for PSS may not be maintained solely through the use of TDM. As a result, there may be several techniques in which synchronization signals may be transmitted by base station <NUM>-a using FDM that reduce the PAPR (or a cubic metric (CM)) of synchronization signals.

In some examples, base station <NUM>-a may use a set of phase offsets for the transmission of synchronization signals sent simultaneously in an FDM manner, where a different phase offset is applied to synchronization signals transmitted on one or more component carriers. For example, a first PSS transmitted in a first component carrier may be phase shifted relative to a second PSS in a second component carrier, where the PSSs may be simultaneously transmitted in the different component carriers. Accordingly, the application of the phase offsets to synchronization signals transmitted over a set of component carriers may reduce the PAPR of the transmitted signal. For example, a PAPR associated with the transmission of PSSs including the phase offset may be lower than the PAPR when PSSs are transmitted without the phase offset. In some cases, a component carrier may include PSS transmission for multiple antenna ports, where the antenna ports each transmit in different directions at the same time. Additionally or alternatively, the synchronization signals having different phase offsets may be transmitted in the frequency domain within a wideband carrier.

Base station <NUM>-a may use a number of techniques for the application of phase offsets to synchronization signals transmitted across one or more component carriers. For example, a phase ramp may be applied across synchronization signals that are associated with different component carriers, or a phase ramp may be applied across synchronization signals that are associated with a same component carrier. In other examples, a sequence may also be used across different component carriers. For instance, a Zadoff-Chu or a maximum length (M) sequence may be applied across different component carriers. In such cases, a short Zadoff-Chu sequence or a short M sequence may be used across respective carriers. Additionally or alternatively, an extended Zadoff-Chu sequence or extended M sequence may be used across the different component carriers.

In some cases, base station <NUM>-a may use different aspects of synchronization signal transmissions when determining the set of phase offsets. For example, the set of phase offsets base station <NUM>-a selects may be based on the number of component carriers within a set of component carriers used to transmit the synchronization signal. The set of phase offsets may also be based on a sequence of synchronization signals. Additionally, the set of phase offsets may also be chosen such that the PAPR or a CM is minimized, or chosen such that the PAPR or CM is less than a threshold. Base station <NUM>-a may determine the set of phase offsets based on a measurement of the PAPR or CM within wireless communications system <NUM>. For example, base station <NUM>-a may perform an initial measurement of PAPR, determine the set of phase offsets based on the measurement, and proceed to use the set of phase offsets going forward.

When transmitting the synchronization signals, base station <NUM>-a may select a sequence to transmit the synchronization signals on the different component carriers. In such cases, the sequence used by base station <NUM>-a (e.g., including a root and a cyclic shift, or a length of a base sequence) may be chosen to reduce the PAPR or CM within the system. For instance, a root and a cyclic shift (or the root and a base sequence length) of the Zadoff-Chu sequence may be chosen to minimize the PAPR or CM. Additionally or alternatively, the Zadoff-Chu sequence may be chosen so that the PAPR or CM of the system remains below a predetermined threshold. Similar techniques may be used for choosing an M sequence such that the PAPR or CM of the system is minimized or remains below a predetermined threshold. For instance, a polynomial and a cyclic shift, or combinations thereof, may be selected to minimize the PAPR or CM, or both.

In some cases, additional synchronization signals may be transmitted with the same phase offset as the PSS in each component carrier. For example, base station <NUM>-a may transmit other synchronization signals (e.g., SSS and PBCH) using the same phase offset as the PSS in each component carrier. The SSS or PBCH in a given component carrier may therefore have a same phase offset relative to the PSS within that component carrier, and SSS and PBCH in other component carriers may have different phase offsets. However, in some cases, the additional synchronization signals may have a different phase offset than the transmitted PSS.

In some examples, base station <NUM>-a may transmit a synchronization signal (e.g., PSS) using only one component carrier for each transmit antenna port. That is, PSSs from different antenna ports may be transmitted on respective component carriers. In such cases, the PAPR (or CM) for the PSS may be reduced, the transmission of a single Zadoff-Chu sequence for the PSS in each component carrier may be associated with a lower PAPR than when multiple Zadoff-Chu sequences are used for antenna ports transmitting PSS across multiple component carriers.

Each antenna port used to transmit the PSS in a single component carrier may also be associated with a wider beam <NUM>. That is, an antenna port of base station <NUM>-a may be transmitting in multiple directions (e.g., using different beams <NUM>) during each symbol, and the beam <NUM> may be wider than when the antenna port is transmitting in a single direction or using a narrow beam <NUM>. Additionally, each antenna port may have a boosted power to transmit the PSS, where the boosted power is greater than when the antenna port is transmitting PSS across multiple component carriers (e.g., in a single direction during each symbol). For example, the antenna port may only be using one of n component carriers for the PSS transmission, and therefore the transmit power for that antenna port may be boosted by a factor of n (e.g., due to the use of a wider beam <NUM>). While the area gain may drop with the wider beam <NUM>, the boosted transmit power may result in a receive power at UE <NUM>-a that is the same as if a signal was transmitted using a single beam <NUM> over multiple component carriers.

In some cases, additional synchronization signals may be transmitted with the same configuration as the PSS transmission. That is, SSS and PBCH from each antenna port may also be transmitted in a single component carrier when PSS is transmitted in this manner. In some cases, this configuration of synchronization signals may indicate an antenna port associated with each component carrier, or may also indicate the choice of transmission beam <NUM>.

<FIG> illustrates an example of a synchronization signal block configuration <NUM> for synchronization signal transmission techniques for PAPR reduction. The synchronization signal block configuration <NUM> may be used by a base station <NUM> to transmit synchronization signals (e.g., PSS, SSS, PBCH, etc.) to a UE <NUM>. For example, synchronization signal block configuration <NUM> may include a number of synchronization signal bursts <NUM> that a UE <NUM> uses for initial access to a cell.

The synchronization signal bursts <NUM> may have a certain duration (e.g., T2) and may be transmitted periodically, where resources may be separated in the time domain by a certain period (e.g., T<NUM>). For example, a synchronization signal burst <NUM> may have a duration of <NUM>, and may be transmitted every <NUM>. Additionally, each synchronization signal burst <NUM> may include a multiple symbols <NUM> (e.g., <NUM> OFDM symbols) where resources for synchronization signals may be allocated.

For example, within a synchronization signal burst <NUM>, multiple consecutive synchronization signal blocks <NUM> may be transmitted in the symbols <NUM>. Each synchronization signal block may include a number of synchronization signals <NUM>, which may include PSS, SSS, PBCH, or mobility reference signal (MRS), or a combination thereof. In some cases, each synchronization signal block <NUM> may be associated with a direction transmission of synchronization signals. That is, synchronization signal blocks <NUM> in each symbol <NUM> may be designated for a transmission in a different direction.

A synchronization signal block <NUM> may include synchronization signals <NUM> that are multiplexed according to TDM or FDM. For example, synchronization signal block <NUM> may include at least one or more PSS, SSS, and PBCH. In some cases, a PAPR of a PSS may improve with TDM (e.g., relative to FDM), where a Zadoff-Chu sequence or M sequence based synchronization signal may maintain a relatively lower PAPR if the PSS is not multiplexed with other signals. Additionally, PBCH demodulation may use the SSS as a reference (e.g., as compared to cases using dedicated reference tones), and may provide more efficient resource utilization.

<FIG> illustrates an example of a transmission scheme <NUM> for synchronization signal transmission techniques for PAPR reduction. Transmission scheme <NUM> may be used by a base station <NUM> to broadcast synchronization signals in multiple directions, where each beam of an antenna port may be associated with a different direction. Additionally, transmission scheme <NUM> may be an example of different antenna ports transmitting synchronization signals across multiple component carriers using a set of phase offsets.

Transmission scheme <NUM> may include multiple antenna port transmissions <NUM> originating from different antenna ports of a base station <NUM>. Each antenna port transmission <NUM> may include multiple symbols <NUM> that correspond to a transmission of synchronization signals using a different beam, where each beam (e.g., b1 through b8) may be associated with a different direction. For instance, a first antenna port transmission <NUM>-a may include symbols <NUM> for four different beams (e.g., b1 through b4) from a first antenna port (AP1). Similarly, a second antenna port transmission <NUM>-b may include symbols <NUM> for four different beams (e.g., b5 through b8) from a second antenna port (AP2).

In some examples, synchronization signals sent by each antenna port transmission <NUM> may use multiple component carriers <NUM> with a set of phase offsets applied to the synchronization signals across the component carriers <NUM>. For example, the PSSs in the first antenna port transmission <NUM>-a and the second antenna port transmission <NUM>-b may be sent using a first component carrier <NUM>-a. Additionally, PSSs sent in a third antenna port transmission <NUM>-c and a fourth antenna port transmission <NUM>-d may be included in a second component carrier <NUM>-b. In the example of <FIG>, the third antenna port transmission <NUM>-c includes transmissions from the same beams as the first antenna port transmission <NUM>-a. The same is illustrated with respect to the fourth antenna port transmission <NUM>-d and the second antenna port transmission <NUM>-b. The synchronization signals corresponding to a given beam may be simultaneously transmitted in a symbol <NUM> of different component carriers. Accordingly, transmission scheme <NUM> may illustrate the transmission of eight different beams for two different antenna ports (e.g., eight different directions for each antenna port) during four symbols <NUM>.

As mentioned above, the synchronization signals transmitted in each component carrier <NUM> may use a set of phase offsets, where the synchronization signals for respective component carriers have a different phase offset. For instance, the first component carrier <NUM>-a may include PSSs with a different phase offset from PSSs transmitted in the second component carrier <NUM>-b. Other synchronization signals (e.g., SSS, PBCH, etc.) transmitted in the component carriers <NUM> may have a same phase offset as the PSSs transmitted in the respective component carrier <NUM>. In some examples, the other synchronization signals may have a different phase offset.

<FIG> illustrates an example of a transmission scheme <NUM> for synchronization signal transmission techniques for PAPR reduction. Transmission scheme <NUM> may be used by base station <NUM> to broadcast synchronization signals in multiple directions, where each beam of an antenna port may be associated with a different direction. Additionally, transmission scheme <NUM> may be an example of different antenna ports transmitting synchronization signals across multiple component carriers using a set of phase offsets.

Transmission scheme <NUM> may include multiple antenna port transmissions <NUM> originating from different antenna ports of base station <NUM>. Each antenna port transmission <NUM> may include multiple symbols <NUM> that correspond to a transmission of synchronization signals using multiple beams, where each beam (e.g., b1 through b8) may be associated with a different direction. For instance, a first antenna port transmission <NUM>-a may include four symbols <NUM> for eight different beams (e.g., b1 through b8) from a first antenna port (AP1), where each symbol <NUM> is associated with two different beams. Similarly, a second antenna port transmission <NUM>-b may include four symbols <NUM> for eight different beams (e.g., b1 through b8) from a second antenna port (AP2).

Synchronization signals sent by each antenna port transmission <NUM> may use a single component carriers <NUM>. For example, the PSSs in the first antenna port transmission <NUM>-a and the second antenna port transmission <NUM>-b may be sent using one component carrier <NUM>. Accordingly, transmission scheme <NUM> may illustrate the transmission of eight different beams for two different antenna ports (e.g., eight different directions for each antenna port) across four symbols <NUM>, but using a single component carrier <NUM>.

In some cases, transmission scheme <NUM> may be associated with a relatively lower PAPR (e.g., as compared to the transmission scheme <NUM> as described with reference to <FIG>). For instance, transmission scheme <NUM> may be used to transmit the PSS for a same number of beams within a same time interval as transmission scheme <NUM>. Accordingly, a single Zadoff-Chu sequence may be used for PSS transmissions using transmission scheme <NUM>, as compared to multiple Zadoff-Chu sequences used across multiple component carriers, which may lead to a reduced PAPR or reduced CM.

<FIG> illustrates an example of a process flow <NUM> in a system that supports synchronization signal transmission techniques for PAPR reduction. Process flow <NUM> may include UE <NUM>-b and base station <NUM>-b, which may be examples of the corresponding devices described with reference to <FIG> and <FIG>. For example, base station <NUM>-b and UE <NUM>-b may operate in a mmW communications system. Process flow <NUM> may illustrate the application of a set of phases to synchronization signals transmitted across multiple component carriers.

At step <NUM>, base station <NUM>-b may optionally measure a current PAPR (or CM) within a system. In some examples, this measurement may be used to determine a set of phase offsets. Additionally or alternatively, this measurement may be a one-time measurement completed by base station <NUM>-b.

At step <NUM>, base station <NUM>-b may identify a set of synchronization signals. For example, base station <NUM>-b identifies a set of PSSs, where each PSS is associated with a different component carrier of a set of component carriers. Base station <NUM>-b identifies a set of SSSs, and multiplexes each PSS and each SSS using TDM.

At step <NUM>, base station <NUM>-b may select a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals. In some cases, the selection of the phase offset may include applying a phase ramp across the synchronization signal each associated with the different component carriers of the set of component carriers. Additionally or alternatively, selecting the phase offset includes applying a sequence, such as a short Zadoff-Chu sequence, an extended Zadoff-Chu sequence, a short M sequence, or an extended M sequence, across the different component carriers of the set of component carriers.

In some examples, base station <NUM>-b may identify the set of phase offsets based at least in part on a number of component carriers of the set of component carriers, or a sequence of the synchronization signals associated with the different component carriers of the set of component carriers, or both. Base station <NUM>-b may also identify a PAPR or a CM associated with the set of phase offsets. Accordingly, identifying the set of phase offsets may be based on minimizing the identified PAPR or the identified CM. In some cases, base station <NUM>-b may identify the PAPR or the CM associated with the set of phase offsets, where identifying the set of phase offsets is based on whether the identified PAPR or the identified CM is less than a predetermined threshold.

At step <NUM>, base station <NUM>-b may transmit synchronization signals to UE <NUM>-b. For example, base station <NUM>-b may transmit each synchronization signal on the different component carriers of the set of component carriers using the selected phase offset. In some cases, the synchronization signals may be transmitted simultaneously using FDM. In some cases, base station <NUM>-b may transmit a synchronization signal block using the selected phase offset, where the synchronization signal block comprises at least one or more of a PSS, an SSS, and a PBCH. That is, the transmission to UE <NUM>-b at step <NUM> may include a number of different synchronization signals that may be multiplexed into a synchronization signal block (such as the synchronization signal block <NUM> described with reference to <FIG>).

In some examples, transmitting each PSS on one or more component carriers includes transmitting each PSS in a different frequency band. Additionally, base station <NUM>-b may select a Zadoff-Chu sequence for the PSS that are transmitted. In some cases, the selection of the Zadoff-Chu sequence may include selecting one or more combinations of a root and a cyclic shift or a base sequence length of the Zadoff-Chu sequence that minimizes a PAPR or a CM. The Zadoff-Chu sequence may also be selected such that the root and the cyclic shift of the Zadoff-Chu sequence corresponds to a PAPR value or a CM value that is below a predetermined threshold. In some examples, base station <NUM>-b may not transmit another signal (e.g., such as another data signal) while transmitting each synchronization signal.

At step <NUM>, UE <NUM>-a may achieve synchronization with base station <NUM>-a based on the received PSS, SSS, and PBCH. That is, UE <NUM>-a may identify a radio frame, a subframe, a slot, and a symbol synchronization in the time domain, and may proceed with access procedures with base station <NUM>-a.

<FIG> illustrates an example of a process flow <NUM> in a system that supports synchronization signal transmission techniques for PAPR reduction. Process flow <NUM> may include a UE <NUM>-c and a base station <NUM>-c, which may be examples of the corresponding devices described with reference to <FIG> and <FIG>. For example, base station <NUM>-c and UE <NUM>-c may operate in a mmW communications system. Process flow <NUM> may illustrate the transmission of PSSs from different antenna ports of base station <NUM>-c using a single component carrier for each antenna port.

At step <NUM>, base station <NUM>-c may identify synchronization signals to be broadcast to multiple UEs <NUM> (e.g., including UE <NUM>-c). For example, a set of PSSs may be identified, where each PSS of the set of PSSs may be associated with a different component carrier of a set of component carriers. In some examples, each PSS of the set of PSSs is associated with a same PSS sequence.

At step <NUM>, base station <NUM>-c may generate a set of synchronization signal blocks (e.g., a synchronization signal block <NUM> as described with reference to <FIG>), where the synchronization signal block may correspond to the different antenna ports. The synchronization signal block may include each PSS, SSS, PBCH, or a combination thereof.

At step <NUM>, base station <NUM>-c may transmit, and UE <NUM>-c may receive the synchronization signal blocks. In some cases, the synchronization signals may be associated with directional transmission from base station <NUM>-c. Transmitting the synchronization signal blocks may include transmitting each synchronization signal block in one or more component carriers of the set of component carriers using a different antenna port of base station <NUM>-c. Additionally or alternatively, transmitting the synchronization signal blocks may include transmitting the synchronization signal blocks simultaneously on a wideband carrier. In some examples, base station <NUM>-c may transmit the synchronization signal blocks in the different component carriers from respective antenna ports of base station <NUM>-c (e.g., where each antenna port uses a single component carrier to transmit the synchronization signal block).

Transmitting the synchronization signal blocks may also include, for example, transmitting each synchronization signal block of the set of synchronization signal blocks using a relatively wider beam. For instance, base station <NUM>-c may use a first beam configuration having a first width greater than a second width of a second beam configuration, where the second beam configuration may be associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port (such as described with reference to <FIG>, <FIG>, <FIG>, and <FIG>). In some cases, the first beam configuration may be based on multiple beam directions used by base station <NUM>-c, where signals may be swept through the different directions.

Base station <NUM>-c may also identify a first transmit power that is greater than a second transmit power, where the second transmit power is associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from the same antenna port. As a result, base station <NUM>-c may transmit each synchronization signal block on one or more component carriers of the set of component carriers from the different antenna ports using the first transmit power. In some cases, base station <NUM>-c may identify an indication of an antenna port associated with the different component carriers, or a selected transmission beam, or both, and transmitting the synchronization signal block may include transmitting the indication. In some examples, base station <NUM>-c may not transmit another signal while transmitting each synchronization signal block.

At step <NUM>, UE <NUM>-c may achieve synchronization with base station <NUM>-c based on the received PSS, SSS, and PBCH. That is, UE <NUM>-c may identify a radio frame, a subframe, a slot, and a symbol synchronization in the time domain, and may proceed with access procedures with base station <NUM>-c.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports synchronization signal transmission techniques for PAPR reduction in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> as described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, synchronization signal manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Receiver <NUM> may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to synchronization signal transmission techniques for PAPR reduction, etc.). Information may be passed on to other components of the device. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>.

Synchronization signal manager <NUM> may be an example of aspects of the synchronization signal manager <NUM> described with reference to <FIG>. Synchronization signal manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the synchronization signal manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The synchronization signal manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, synchronization signal manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, synchronization signal manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to a receiver, a transmitter, a transceiver, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

Synchronization signal manager <NUM> may identify a set of synchronization signals, where, in some cases, each synchronization signal of the set of synchronization signals may be associated with a different component carrier of a set of component carriers. Synchronization signal manager <NUM> may also select a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals and transmit each synchronization signal using the selected phase offsets, the set of synchronization signals being simultaneously transmitted using FDM. In some examples, the synchronization signal manager <NUM> may identify a set of synchronization signal blocks and may transmit each synchronization signal block of the set of synchronization signal blocks. In such cases, each synchronization signal block may be transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier.

<FIG> shows a block diagram <NUM> of wireless device <NUM> that supports synchronization signal transmission techniques for PAPR reduction in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a base station <NUM> (e.g., a base station that operates in mmW frequency spectrum) as described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, synchronization signal manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Synchronization signal manager <NUM> may be an example of aspects of the synchronization signal manager <NUM> described with reference to <FIG>. Synchronization signal manager <NUM> may also include synchronization signal component <NUM>, phase offset component <NUM>, and component carrier manager <NUM>.

Synchronization signal manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the synchronization signal manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a DSP, an ASIC, a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

Synchronization signal component <NUM> may identify a set of synchronization signals. In some cases, each synchronization signal may be associated with a different component carrier of a set of component carriers. In some examples, the set of synchronization signals includes PSSs, or SSSs, or a combination thereof. In some cases, each synchronization signal of the set of synchronization signal is associated with a same sequence. In some examples, synchronization signal component <NUM> may identify a set of synchronization signal blocks. In some cases, each synchronization signal block includes at least one or more of a PSS, a SSS, a PBCH, and a DMRS of the PBCH.

Phase offset component <NUM> may select a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals and may identify the set of phase offsets based on a number of component carriers of the set of component carriers, or a sequence of the synchronization signals associated with the different component carriers of the set of component carriers, or both. In some examples, phase offset component <NUM> may identify a PAPR or a CM associated with the set of phase offsets, where identifying the set of phase offsets is based on minimizing the identified PAPR or the identified CM. Additionally or alternatively, phase offset component <NUM> may identify a PAPR or a CM associated with the set of phase offsets, where identifying the set of phase offsets is based on whether the identified PAPR or the identified CM is less than a predetermined threshold. In some cases, selecting the phase offset includes applying a phase ramp across the synchronization signals each associated with the different component carriers of the set of component carriers.

In some cases, selecting the phase offset includes applying a sequence across different component carriers of a set of component carriers. The sequence may include a short Zadoff-Chu sequence, or an extended Zadoff-Chu sequence, or a short M sequence, or an extended M sequence. In some examples, selecting the phase offset includes applying a short Zadoff-Chu sequence across the different component carriers of the set of component carriers. In some cases, selecting the phase offset includes applying an extended Zadoff-Chu sequence across the different component carriers of the set of component carriers.

Component carrier manager <NUM> may transmit each synchronization signal on one or more component carriers of a set of component carriers using the selected phase offset. In some examples, component carrier manager <NUM> may transmit the set of synchronization signals using the selected phase offsets, the set of synchronization signals being simultaneously transmitted using FDM. In some cases, transmitting the set of synchronization signals includes transmitting each synchronization signal on one or more component carriers of a set of component carriers. In some examples, transmitting each synchronization signal on the different component carriers includes transmitting each synchronization signal in a different radio frequency band. In some cases, transmitting the set of synchronization signals includes transmitting the set of synchronization signals simultaneously in a frequency domain within a wideband carrier.

Additionally or alternatively, component carrier manager <NUM> may transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier. In some cases, transmitting each synchronization signal on one or more component carriers includes transmitting each synchronization signal in a different frequency band. In some cases, transmitting each synchronization signal includes transmitting each synchronization signal on different component carriers of a set of component carriers, where each synchronization signal may be associated with a different component carrier of the set of component carriers. In some cases, transmitting each PSS includes refraining from transmitting another signal while transmitting each synchronization signal. Additionally or alternatively, transmitting each synchronization signal includes refraining from transmitting a data signal while transmitting each synchronization signal.

In some examples, transmitting each synchronization signal block includes transmitting each synchronization signal block using a different antenna port of the base station or using a same antenna port of the base station. In some cases, transmitting each synchronization signal block on the one or more component carriers includes transmitting each synchronization signal block on different component carriers of the set of component carriers, each synchronization signal block associated with a different component carrier of the set of component carriers. In some examples, transmitting each synchronization signal block includes transmitting each synchronization signal block using a first beam configuration having a first width greater than a second width of a second beam configuration, the second beam configuration associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port. In some cases, the first beam configuration is based at least in part on a plurality of beam directions. In some examples, transmitting each synchronization signal block includes refraining from transmitting another signal while transmitting each synchronization signal block.

<FIG> shows a block diagram <NUM> of a synchronization signal manager <NUM> that supports synchronization signal transmission techniques for PAPR reduction in accordance with various aspects of the present disclosure. The synchronization signal manager <NUM> may be an example of aspects of a synchronization signal manager <NUM>, a synchronization signal manager <NUM>, or a synchronization signal manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The synchronization signal manager <NUM> may include synchronization signal component <NUM>, phase offset component <NUM>, component carrier manager <NUM>, SSS manager <NUM>, multiplexing component <NUM>, sequence selector <NUM>, synchronization signal block manager <NUM>, and transmit power component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Additionally or alternatively, component carrier manager <NUM> may transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier. In some cases, transmitting each synchronization signal on one or more component carriers includes transmitting each synchronization signal in a different frequency band. In some cases, transmitting each synchronization signal includes transmitting each synchronization signal on different component carriers of a set of component carriers, where each synchronization signal may be associated with a different component carrier of the set of component carriers. In some cases, transmitting each synchronization signal block includes refraining from transmitting another signal while transmitting each synchronization signal block. Additionally or alternatively, transmitting each synchronization signal block includes refraining from transmitting a data signal while transmitting each synchronization signal block.

SSS manager <NUM> may identify a set of SSSs. Multiplexing component <NUM> may multiplex each PSS and each SSS of a set of synchronization signals using time division multiplexing. Sequence selector <NUM> may select one or more sequences for the set of synchronization signals. In some cases, the one or more sequences may include a Zadoff-Chu sequence, or a M sequence, or a combination thereof. In some cases, selecting the Zadoff-Chu sequence includes selecting a root and a base sequence length of the Zadoff-Chu sequence that minimizes a PAPR or a CM. In some cases, selecting the Zadoff-Chu sequence includes selecting a root and a base sequence length of the Zadoff-Chu sequence that corresponds to a PAPR value or a CM value that is below a predetermined threshold. In some cases, selecting the one or more sequences includes selecting one or more combinations of a root and a cyclic shift of a Zadoff-Chu sequence that minimizes a PAPR or a CM; or selecting one or more combinations of a polynomial and a cyclic shift of an M sequence that minimized the PAPR or the CM. In some examples, selecting the one or more sequences includes selecting one or more combinations of a root and a cyclic shift of a Zadoff-Chu sequence that corresponds to a PAPR value or a CM value that is below a predetermined threshold; or selecting one or more combinations of a polynomial and a cyclic shift of an M sequence that corresponds to a PAPR value or a CM value that is below a predetermined threshold.

Synchronization signal block manager <NUM> may generate a synchronization signal block corresponding to the different antenna port, transmit the synchronization signal block in one or more component carriers of the set of component carriers from the different antenna port. Synchronization signal block manager <NUM> may also identify an indication of an antenna port associated with the component carriers, or a selected transmission beam, or both, where transmitting the synchronization signal block includes transmitting the indication. In some cases, synchronization signal block manager <NUM> may transmit a synchronization signal block using the selected phase offset, where the synchronization signal block includes at least one or more of a PSS, an SSS, and a PBCH.

Transmit power component <NUM> may identify a first transmit power greater than a second transmit power, the second transmit power associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port, where transmitting each synchronization signal block in one or more component carriers of the set of component carriers from the different antenna port includes using the first transmit power.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports synchronization signal transmission techniques for PAPR reduction in accordance with various aspects of the present disclosure. Device <NUM> may be an example of or include the components of wireless device <NUM>, wireless device <NUM>, or a base station <NUM> as described with reference to <FIG>, <FIG> and <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including synchronization signal manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, network communications manager <NUM>, and base station communications manager <NUM>. These components may be in electronic communication via one or more busses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more UEs <NUM>.

Processor <NUM> may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a central processing unit (CPU), a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting synchronization signal transmission techniques for PAPR reduction).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support synchronization signal transmission techniques for PAPR reduction. Software <NUM> may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software <NUM> may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

Network communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the network communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a DSP, an ASIC, a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The network communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, network communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, network communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to a receiver, a transmitter, a transceiver, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

Base station communications manager <NUM> may manage communications with other base stations <NUM>, and may include a controller or scheduler for controlling communications with UEs <NUM> in cooperation with other base stations <NUM>. For example, the base station communications manager <NUM> may coordinate scheduling for transmissions to UEs <NUM> for various interference mitigation techniques such as beamforming or joint transmission. In some examples, base station communications manager <NUM> may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations <NUM>.

Base station communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the base station communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, DSP, an ASIC, a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The base station communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, base station communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, base station communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to a receiver, a transmitter, a transceiver, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

<FIG> shows a flowchart illustrating a method <NUM> for synchronization signal transmission techniques for PAPR reduction in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a base station <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a synchronization signal manager as described with reference to <FIG>. In some examples, a base station <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station <NUM> may perform aspects the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> may identify a set of synchronization signals. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a synchronization signal component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may select a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit the set of synchronization signals using the selected phase offsets, the set of synchronization signals being simultaneously transmitted using frequency division multiplexing. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a component carrier manager as described with reference to <FIG>.

After identifying the set of synchronization signals, the base station <NUM> may select a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals. In some examples, the base station <NUM> may use various techniques to select the phase offset. For instance, at block <NUM> the base station may optionally select the phase offset by applying a phase ramp across the synchronization signals each associated with different component carriers of a set of component carriers. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

At block <NUM>, the base station <NUM> may optionally select the phase offset by applying a short Zadoff-Chu sequence or a short M sequence across the different component carriers of the set of component carriers. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

Additionally or alternatively, the base station <NUM> may optionally select the phase offset by applying an extended Zadoff-Chu sequence or an extended M sequence across the different component carriers of the set of component carriers at block <NUM>. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may identify a set of phase offsets based at least in part on a number of component carriers of a set of component carriers, or a sequence of the synchronization signals associated with different component carriers of the set of component carriers, or both. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may select a phase offset from a set of phase offsets for each synchronization signal. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a phase offset component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may identify a set of synchronization signal blocks. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a synchronization signal component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a component carrier manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may identify a first transmit power greater than a second transmit power, the second transmit power associated with transmitting a synchronization signal block over multiple component carriers of a set of component carriers from a same antenna port. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a transmit power component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit each synchronization signal block of the set of synchronization signal blocks, each synchronization signal block being transmitted on one or more component carriers of a set of component carriers or transmitted simultaneously on a wideband carrier, where transmitting each synchronization signal block includes using the first transmit power and using a first beam configuration having a first width greater than a second width of a second beam configuration. In some examples, the first beam configuration is based at least in part on a plurality of beam directions. Additionally, the second beam configuration may be associated with transmitting a synchronization signal block over multiple component carriers of the set of component carriers from a same antenna port. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by a component carrier manager as described with reference to <FIG>.

In some examples, aspects from two or more of the methods <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> described with reference to <FIG> may be combined. It should be noted that the methods <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are just example implementations, and that the operations of the methods <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> may be rearranged or otherwise modified such that other implementations are possible.

The terms "system" and "network" are often used interchangeably. A code division multiple access (CDMA) system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-<NUM>, IS-<NUM>, and IS-<NUM> standards. A time division multiple access (TDMA) system may implement a radio technology such as Global System for Mobile Communications (GSM).

An orthogonal frequency division multiple access (OFDMA) system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications system (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of Universal Mobile Telecommunications System (UMTS) that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, NR, and Global System for Mobile communications (GSM) are described in documents from the organization named "3rd Generation Partnership Project" (3GPP). While aspects an LTE or an NR system may be described for purposes of example, and LTE or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE or NR applications.

In LTE/LTE-A networks, including such networks described herein, the term evolved node B (eNB) may be generally used to describe the base stations. The wireless communications system or systems described herein may include a heterogeneous LTE/LTE-A or NR network in which different types of evolved node B (eNBs) provide coverage for various geographical regions. For example, each eNB, next generation NodeB (gNB), or base station may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNB, gNB, Home NodeB, a Home eNodeB, or some other suitable terminology. The non-transitory computer-readable media may comprise RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure.

By way of example, and not limitation, non-transitory computer-readable media may comprise RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.

Claim 1:
A method (<NUM>, <NUM>, <NUM>, <NUM>) for wireless communication, the method performed by a base station (<NUM>), the method comprising:
identifying (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) a set of synchronization signals, wherein the set of synchronization signals comprises primary synchronization signals, PSSs, secondary synchronization signals, SSSs, or a combination thereof, and multiplexing each PSS and each SSS of the set of synchronization signals using time division multiplexing;
selecting (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) a phase offset from a set of phase offsets for each synchronization signal of the set of synchronization signals, the set of phase offsets including a first phase offset and a second phase offset; and
transmitting (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) each synchronization signal of the set of synchronization signals on different component carriers of a set of component carriers using the selected phase offset, the set of synchronization signals being simultaneously transmitted using frequency division multiplexing, wherein each synchronization signal is associated with a different component carrier of the set of component carriers, and wherein a first synchronization signal of the set of synchronization signals is phase shifted according to the first phase offset and a second synchronization signal of the set of synchronization signals is phase shifted according to the second phase offset, wherein the first phase offset is different to the second phase offset.