Patent Description:
The following relates generally to wireless communication, and more specifically to synchronization signal design.

Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system or a New Radio (NR) system).

In wireless communication systems, such as an LTE system, multiple synchronization signals are used for cell acquisition. One signal is a primary synchronization signal (PSS), which is used for timing and frequency synchronization and may also indicate a portion of the cell identifier (ID) associated with a given cell. In LTE systems, for instance, there are three different PSS sequences, each of which is generated using a different Zadoff-Chu root. A secondary synchronization signal (SSS) may carry additional synchronization information and system information such as the remaining portion of the cell ID and the frame boundary index. These synchronization signals may be transmitted from a base station to a UE over adjacent symbols using one or more sub-carriers of a carrier frequency. Document <CIT> discloses a method of generating a code sequence and method of adding additional information using the same, by which a code sequence usable for a channel for synchronization is generated and by which a synchronization channel is established using the generated sequence. The additional information is added to a cell common sequence for time synchronization and frequency synchronization, includes the steps of generating the sequence repeated in time domain as many as a specific count, masking the sequence using a code corresponding to the additional information to be added, and transmitting a signal including the masked sequence to a receiving end. Document <CIT> discloses that in a heterogeneous network deployment that includes one or more macro base stations and one or more low power nodes, a technique can be provided to encode network operational information using phase differences in synchronization signals transmitted by a network node. The synchronization signals may be one of the first signals that a user equipment (UE) attempts to locate when attempting to join a wireless network. The phase-encoded network operational information indicates to the UE where to locate a geometry indicator transmission from a low power node that is a part of the network, but is not the node that transmits the synchronization signals. The geometry indicator transmission may include identity information for the transmitting node and may be transmitted at a pre-determined nominal transmit power. Document 3GPP, R1-<NUM> relates to NR Initial Access Procedure with multi-stage synchronization signals.

The invention is defined in independent claims. Dependent claims concern particular embodiments of the invention. Any subject matter presented in the description but not falling under the claims constitutes an aspect of the disclosure which may be useful for understanding the invention.

The described techniques relate to improved methods, systems, devices, or apparatuses that support synchronization signal design. Generally, the described techniques provide for the communication of information based on a channel correlation between synchronization signals. In some cases, this information may indicate a physical channel timing parameter, a physical channel presence indicator, or a system information parameter.

The channel correlation may indicate a phase shift between two or more signals such as synchronization signals (e.g., primary synchronization signal (PSS), secondary synchronization signal (SSS)), broadcast channels (e.g., physical broadcast channel (PBCH), demodulation reference signals (DMRS) for PBCH, beam reference signals, channel reference signals, or other timing reference signals). The channel correlation may also be associated with a precoding matrix used for transmission of the synchronization reference signals or broadcast channels. In some instances, channel estimations for each of multiple synchronization signals may be compared and based on the comparison, the precoding matrix used for transmission may be determined. Based on the channel correlation or channel estimate(s), various communication information may be transmitted or received.

In some wireless communications system, such as a New Radio (NR) system, certain resources may be periodically allocated for the transmission of synchronization signals and broadcast channels, which are used during cell acquisition. Resources for synchronization signals and broadcast channels may be multiplexed according to a Frequency Division Multiplexing (FDM) scheme or a Time Division Multiplexing (TDM) scheme. In FDM, two or more signals are transmitted concurrently using different frequencies (e.g., different sub-carriers). In TDM, two or more signals may be communicated using the same or different frequency but over different time periods (e.g., different symbol periods). In some TDM cases, a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) may be transmitted in adjacent symbols using the same sub-carriers. For example, the PSS and the SSS may be transmitted periodically (e.g., every <NUM> milliseconds (ms)) and may be transmitted over adjacent symbols. Each set of resources may be referred to as a synchronization signal burst (SSBurst) or SSBurst set. Within a single SSBurst or SSBurst set, there may be multiple synchronization signal blocks (SSBlocks) which span multiple sub-carriers. In some examples, a PSS, an SSS, and one or more Physical Broadcast Channels (PBCHs) may be transmitted within each SSBlock and may be multiplexed according to a TDM scheme. In some cases, one or more demodulation reference signals (DMRS) may be transmitted within one or more PBCH symbols. The SSBurst or SSBurst set may be transmitted by a base station (e.g., periodically) to facilitate cell acquisition. In a New Radio system, for example, the SSBurst or SSBurst set may transmitted by a base station using a beamforming sweep pattern. During a beamforming transmission of the SSBurst, each SSBlock within the SSBurst or SSBurst set, may be transmitted in a different direction.

In some examples, a precoding relationship between a first synchronization signal (e.g., the PSS) and a second synchronization signal (e.g., the SSS) may be established and may be used during transmission of the PSS and SSS. The precoding relationship may be a shift in the phase between the PSS and the SSS or a precoding matrix applied across subcarriers and antenna ports for transmission of the PSS and the SSS. In some cases, the techniques described may apply to other examples of synchronization or reference signals. For instance, the first synchronization signal may be one of a primary synchronization signal or a secondary synchronization signal, and the second synchronization signal may be a DMRS signal. In some other cases, the first synchronization signal may be one of a first DMRS signal or a first beam reference signal, and the second synchronization signal may be one of a second DMRS signal or a second beam reference signal. According to some aspects, a UE receiving the PSS and SSS may determine a channel correlation between the PSS and SSS to determine various communication information, which may be used by the UE to enhance cell acquisition. For example, the communication information may indicate a physical channel timing parameter associated with the synchronization signals or broadcast channels such as a synchronization periodicity, a PBCH periodicity, a beam sweep periodicity, etc. In other examples, the communication information may include a physical channel presence indicator that indicates the presence of a PBCH transmission, a mobility reference signal (MRS) transmission, a beam or channel reference signal transmission, or combinations thereof. In some cases, the communication information may also include other timing parameters or system information, such as a cyclic prefix (CP) type, a cell identifier (ID), timing or frequency synchronization information, or other system information associated with the cell. In some cases, the precoding relationship or channel correlation between the PSS and SSS may convey opportunistic (e.g., non-essential or redundant) information to optimize UE receiver processing. For example, in some cases, an index of PBCH within a BCH TTI may be utilized by the UE to acquire system timing. In some cases, this information pertaining to PBCH timing may assist a UE in optimizing the number of PBCH blind decodes. In some other cases, the opportunistic information may be used to provide an indication of a physical channel timing parameter (e.g., relative position of SSS within a frame, BCH TTI boundaries including an index of the SSBurst set within PBCH TTI and/or a redundancy version of PBCH), an indication of synchronization modes (e.g., initial acquisition, RRC-idle mode, or RRC-connected mode), DMRS information (e.g., DMRS resources, DMRS configuration in PBCH), or a combination thereof. Furthermore, in some cases, the UE may not be able to determine the opportunistic information through the phase of the SSS. In such cases, the communication information may also be transmitted in other signals (e.g., a master information block (MIB) or system information block (SIB), etc.), or acquired through blindly checking multiple hypotheses while processing the other signals or channels.

<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 an LTE/LTE-A network, a millimeter wave (mmW) network, or an 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.

Each base station <NUM> may provide communication coverage for a respective geographic coverage area <NUM>. Communication links <NUM> shown in wireless communications system <NUM> may include uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. 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 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.

In some cases, an MTC device may operate using half-duplex (one-way) communications at a reduced peak rate. MTC devices may also be configured to enter a power saving "deep sleep" mode when not engaging in active communications. In some cases, MTC or IoT devices may be designed to support mission critical functions and wireless communications system may be configured to provide ultra-reliable communications for these functions.

The core network may be an evolved packet core (EPC), which may include at least one Mobile Management Entity (MME), at least one Serving Gateway (S-GW), and at least one Packet Data Network Gateway (P-GW). All user IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The operators IP services may include the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a Packet-Switched (PS) Streaming Service (PSS).

Each access network entity may communicate with a number of UEs <NUM> through a number of other access network transmission entities, each of which may be an example of a smart radio head, or a transmission/reception point (TRP).

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 (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation.

An eCC may be characterized by one or more features including: wider bandwidth, shorter symbol duration, shorter transmission time interval (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).

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 Network (WLAN) networks 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.

Thus, wireless communications system <NUM> may support 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) and a receiver (e.g., a UE), where both the transmitter and receiver are equipped with multiple antennas. 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 multiple use antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM>.

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 aspects, a base station <NUM> may transmit at least one of a PSS, an SSS, a PBCH, a DMRS, or a beam reference signal, which may be used by a UE <NUM> during cell acquisition. The base station <NUM> may establish a precoding relationship between two or more of the PSS, SSS, PBCH, DMRS, or beam reference signal, which indicates communication information such as a physical channel timing parameter (e.g., indication of BCH TTI boundaries), a physical channel presence indicator, or a system information parameter. The system information parameter may be, for example, an indicator of an operation mode (e.g., initial acquisition, synchronization, or beam or mobility management, in an RRC-idle or RRC-connected mode) or DMRS configuration. A UE <NUM> may determine a channel estimation for the PSS, SSS, PBCH, or beam reference signal based on channel correlation(s) associated with the precoding relationship and may then use the determined channel estimation(s) to obtain various communication information. In some cases, the information conveyed through the phase of the SSS (e.g., by using PSS as a phase reference), may be opportunistic in nature. For example, in some cases, the SSS phase may carry information about PBCH timing, which in turn may assist a UE in reducing the number of PBCH blind decodes.

<FIG> illustrates an example of a wireless communication system <NUM> for synchronization signal design. Wireless communications system <NUM> may include base station <NUM>-a and UE <NUM>-a, which may be examples of the corresponding devices described with reference to <FIG>.

In wireless communication system <NUM>, base station <NUM>-a may transmit a first synchronization signal and a second synchronization signal to UE <NUM>-a using beamforming. For instance, the base station <NUM>-a may transmit (e.g., radially) synchronization signal beams <NUM> in different directions. The synchronization signal beams <NUM> may each include an SSBlock of an SSBurst and may be transmitted periodically. Each of the synchronization signal beams <NUM> may correspond to a single SSBlock of an SSBurst such that each SSBlock of the SSBurst is transmitted in a different direction.

The SSBlock may span multiple tones or multiple resource blocks (RBs) over multiple symbols. In a TDM scheme, each of the multiple symbols may be allocated for transmission of either a PSS, an SSS, or a PBCH. In some instances, the base station <NUM>-a may identify communication information corresponding to a cell and based on the communication information, the base station <NUM>-a may establish a channel correlation between two or more signals of the SSBlock (e.g., the PSS and the SSS). In some examples, the channel correlation may be a phase shift between the PSS and the SSS and may be used to indicate the communication information. For instance, the base station <NUM>-a may transmit the SSBlock (and the corresponding PSS and SSS of the SSBlock) based on the channel correlation such that the PSS and SSS are transmitted having a phase shift with respect to each other.

In some cases, the phase shift or channel correlation between the PSS and SSS, or any other combination of synchronization signals (e.g., PSS and DMRS, or SSS and DMRS) may convey non-essential and/or opportunistic information to optimize UE receiver processing. For example, in some cases, an index of PBCH within a BCH TTI may be utilized by the UE to acquire system timing. In some cases, this information pertaining to PBCH timing may assist a UE in optimizing the number of PBCH blind decodes. In some other cases, the opportunistic information may be used to provide an indication of a physical channel timing parameter (e.g., relative position of SSS within a frame, BCH TTI boundaries including an index of the SSBurst set within PBCH TTI and/or a redundancy version of PBCH), an indication of synchronization modes (e.g., initial acquisition, RRC-idle mode, or RRC-connected mode), DMRS information (e.g., DMRS resources, DMRS configuration in PBCH), or a combination thereof. In some cases, the non-essential and/or opportunistic information may comprise <NUM> or <NUM> bits. Furthermore, in some cases, the opportunistic information may comprise a portion of the SS block index.

In some examples, the precoding relationship may be established by using a precoding matrix applied across multiple antenna ports and sub-carriers (e.g., SFBC) for transmission of the PSS, the SSS, and/or the DMRS. For instance, the UE <NUM>-a may receive the SSBlock transmitted by base station <NUM>-a and may determine a channel estimation of the SSS and the PSS over different sets of tones. Based on the channel estimation for the PSS and the SSS, the UE <NUM>-a may determine a channel estimation difference, which may be used to obtain or otherwise determine the precoding matrix used by the base station for transmitting the PSS or the SSS over the multiple antenna ports.

<FIG> illustrates an example of a frame structure <NUM> for synchronization signal design. In <FIG>, an example of a first SSBurst or SSBurst set <NUM>-a and a second SSBurst or SSBurst set <NUM>-b, that may be used for transmitting communication information is shown. In some cases, the first SSBurst <NUM>-a and the second SSBurst <NUM>-b may be similar in that transmission of the SSBursts <NUM>-a and <NUM>-b is periodic. In some cases, the first SSBurst <NUM>-a and the second SSBurst <NUM>-b represent aspects of techniques performed by a UE <NUM> or base station <NUM> as described with reference to <FIG> and <FIG>.

As shown in this example, resources are periodically allocated for the transmission of synchronization signals, which may be used by a UE (e.g., UE <NUM>) during cell acquisition. For instance, synchronization signals may be allocated for transmission periodically every time period T<NUM> <NUM>. The time period <NUM> may be predetermined by a base station (e.g., base station <NUM>) and in some cases, T<NUM> may be <NUM>. Each SSBurst <NUM> spans a time duration T<NUM> <NUM> and in some examples, T<NUM> may be at most <NUM>.

Within one SSBurst <NUM>, there may be multiple SSBlocks (<NUM> through n). For instance, each SSBurst <NUM> may include a Oth SSBlock <NUM> and a 1st SSBlock <NUM>. In some examples, each SSBlock may span multiple RBs (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>). Each RB may span multiple tones having a given tone spacing (e.g., <NUM>, <NUM>, <NUM>, etc.). In some examples, each SSBlock may allocate resources for the transmission of multiple signals according to a TDM scheme. For instance, SSBlock <NUM>-a is shown allocating a first symbol for a broadcast channel <NUM> (e.g., a PBCH), a second symbol for a first synchronization signal <NUM> (e.g., PSS or SSS), a third symbol for a second synchronization signal <NUM> (e.g., a PSS or SSS), and fourth symbol for a second broadcast channel <NUM> (e.g., PBCH). Therefore, in some cases, a PSS, an SSS, and multiple PBCHs may be transmitted within SSBlock <NUM>-a. In some cases, the PBCH may be wider in frequency domain than the PSS, the SSS, or both. For example, the PBCH may occupy <NUM> tones, whereas the PSS or SSS may occupy <NUM> tones. Furthermore, in some cases, the center frequency of all three may be aligned. In some cases, pilot tones (e.g., DMRS) may be transmitted at least in the frequency regions where PSS or SSS are not transmitted.

According to some aspects, there may be a maximum of <NUM> SSBlocks within each SSBurst (or SSBurst set) <NUM> and each SSBlock may be transmitted directionally using different transmission beams. Therefore, during the transmission of the SSBurst <NUM>, each SSBlock is transmitted towards a different direction. The SSBurst may cover an angular range (e.g., <NUM> degrees, etc.) of a cell.

In some examples, the first synchronization signal <NUM> and the second synchronization signal <NUM> are transmitted back to back in adjacent symbols and a broadcast channel may be transmitted in the first and last symbols of the SSBlock. Thus, as the first synchronization signal <NUM> and the second synchronization signal <NUM> are surrounded by the first broadcast channel <NUM> and the second broadcast channel <NUM>, a UE receiving the transmitted SSBlock may be able to detect a frequency offset between the first broadcast channel <NUM> and the second broadcast channel <NUM>. For instance, a carrier frequency offset may be calculated using a phase difference between the first symbol and the fourth symbol of SSBlock <NUM>-a.

In some wireless communication systems, the base station <NUM> may transmit multiple first synchronization signals <NUM> in different directions. The UE <NUM> may receive multiple spatially separated first synchronization signals <NUM> from different base stations <NUM>. In some examples, the base station <NUM> may transmit multiple second synchronization signals <NUM> in different directions. The UE <NUM> may receive multiple spatially separated second synchronization signals <NUM> from different base stations <NUM>. Therefore in some wireless communication systems, because of beam forming, the interference pattern on the first synchronization signal <NUM>, observed by the UE <NUM>, is similar to the interference pattern on the second synchronization signal <NUM>. In other words, in wireless communication systems, a channel estimation for the first synchronization signal <NUM> is similar to a channel estimation for the second synchronization signal <NUM>. A coherent detection of the second synchronization signal <NUM> based on the first synchronization signal <NUM> is therefore possible by the UE <NUM>. In wireless communication systems, the base station <NUM> may transmit the first synchronization signal <NUM>. In some examples, the base station <NUM> may configure the second synchronization signal <NUM> to transmit extra information through a precoding relationship of the second synchronization signal <NUM> with respect to the first synchronization signal. In this example, the first synchronization signal <NUM> may be a primary synchronization signal and the second synchronization signal <NUM> may be a secondary synchronization signal. In yet other examples, the locations of the primary synchronization signal and the secondary synchronization signal may be reversed. The UE <NUM> receiving the first synchronization signal <NUM> and the second synchronization signal <NUM> may be configured to decode the extra information by examining the precoding relationship between the first synchronization signal <NUM> and the second synchronization signal <NUM>.

In some NR systems, although one or more neighboring synchronous cells may be configured to transmit the SSBlocks using the same resources, the SSBlocks are likely to be transmitted in different directions when each of the neighboring cells is transmitting using beamforming. Due to this spatial separation, the UE <NUM> receiving the first synchronization signal <NUM> and the second synchronization signal <NUM> may experience limited interference and if the signals are transmitted in adjacent or proximal symbols having relatively short symbol durations (e.g., ~<NUM>), the first synchronization signal <NUM> and the second synchronization signal <NUM> may experience similar effects from, for example, carrier frequency offset, phase noise, Doppler shift, etc. (i.e., may experience similar channels). Thus, in some cases, the channel observed and estimated for the first synchronization signal <NUM> may be used to equalize the channel observed for the second synchronization signal <NUM>.

In one example, a phase shift between the first synchronization signal <NUM> and the second synchronization signal <NUM> may be introduced in a single-layer transmission. In some examples, a base station <NUM> may transmit the first synchronization signal <NUM> and the second synchronization signal <NUM> on all ports without precoding (i.e., the same symbol is transmitted from each port of the base station <NUM>). In such a case, a first sequence associated with the first synchronization signal <NUM> may be defined as b(<NUM>,. , N - <NUM>), where N represents the number of tones used for transmission of the first synchronization signal <NUM> and b(<NUM>) is the Oth tone of the first synchronization signal <NUM>. The first synchronization signal <NUM> may be transmitted from port i of a base station antenna and if the first synchronization signal <NUM> is a PSS, it may be represented as <MAT>, where n is the tone used for transmission. As the first synchronization signal <NUM> transmitted from port i undergoes a channel (represented by Hi(n)), the received signal (e.g., received by a UE <NUM>) may be represented as ypss(n) using the following equation: <MAT> where Hpss(n) = H<NUM>(n) + ··· + HP-<NUM>(n), P is the number of ports and w<NUM>(n) is noise.

The second synchronization signal <NUM> may be defined as d(<NUM>,. , N - <NUM>), where N represents the number of tones used for transmission of the second signal d(<NUM>) is the Oth tone of the second synchronization signal <NUM>. In this example, the second synchronization signal <NUM> may be an SSS and transmitted from port i of a base station antenna, and thus may be represented as <MAT>, where n is the tone used for transmission. As the second synchronization signal <NUM> undergoes a channel (represented by Hi(n)), the received signal (e.g., received by a UE <NUM>) may be represented by ysss(n) using the following equation: <MAT> where Hsss(n) = H<NUM>(n) + ··· + HP-<NUM>(n), P is the number of ports and w<NUM>(n) is noise. We note that, as mentioned above, the channels, observed on a port p and tone n, in the PSS and SSS symbols are expected to be similar, and hence it is denoted by Hp(n) for both PSS and SSS.

To illustrate1-bit of information carried through the phase of the second synchronization signal <NUM>, the transmitted second synchronization signal <NUM> may include either a base sequence represented by d(<NUM>,. , N - <NUM>) or a π shifted base sequence represented by -d(<NUM>,. , N - <NUM>). Thus, if Hpss(n) = Hsss(n) := H(n), The received second synchronization signal for base sequence d may be represented using the following equation: <MAT>
and the received second synchronization signal for base sequence - d (i.e., with π shift) may be represented using the following equation: <MAT>.

After receiving the second synchronization signal <NUM>, the channel H(n) may be estimated using the received first synchronization signal <NUM> with base sequence b (i.e., PSS (b)) by comparing it with the channel estimated using the second synchronization signal <NUM> with base sequence d (i.e., SSS(d)). In one example, if the phase between the PSS(b) and the SSS(d) observed by the UE <NUM> is approximately zero, then the UE <NUM> may be able to determine that d was transmitted by the base station <NUM>, while if the phase between PSS(b) and SSS(d) observed by the UE <NUM> is about π, then the UE <NUM> may be able to determine that -d was transmitted by the base station <NUM>. Based on this phase shift, a UE <NUM> may be able to determine various communication information.

In some cases, the PSS and SSS may be transmitted on the same antenna port, which may allow for coherent detection of SSS by using PSS as a phase reference. Furthermore, in some cases, <NUM> or <NUM> bits of information may be transmitted through the phase of the SSS signal, for example, opportunistic (e.g., non-essential or redundant) information to optimize UE receiver processing. For example, in some cases, reliability acquiring the <NUM> or <NUM> bits of information may serve to decrease or optimize complexity associated with receiving subsequent signals or channels, while system acquisition does not depend on acquiring the information.

In some cases, the opportunistic information may be utilized to provide an indication of a PBCH index within a BCH TTI. For example, in some cases, the transmission periodicity of PBCH for initial acquisition may be <NUM>, and the BCH TTI may be a duration of <NUM>. Thus, a UE may need some indication of an index of PBCH within a BCH TTI to acquire system timing. In such cases, the opportunistic information carried via the phase of the SSS may assist a UE in optimizing the number of PBCH blind decodes, in order to acquire system timing. In some other cases, the UE may blindly decode multiple redundancy versions of NR-PBCH to acquire system timing. Alternatively, in some cases, the UE may not reliably decode or receive the <NUM> or <NUM> bit information through the phase of the SSS. In such cases, since the <NUM> or <NUM> bit information is opportunistic in nature, the UE may acquire the PBCH index through other means, such as through the MIB or SIB. Furthermore, in such cases, the UE may need to check multiple hypotheses when combining two or more PBCH channels across SSBurst sets.

In some other cases, the opportunistic information may be used to provide an indication of a physical channel timing parameter (e.g., relative position of SSS within a frame, BCH TTI boundaries including an index of the SSBurst set within PBCH TTI and/or a redundancy version of PBCH), an indication of synchronization modes (e.g., initial acquisition, RRC-idle mode, or RRC-connected mode), DMRS information (e.g., DMRS resources, DMRS configuration in PBCH), or a combination thereof. In some cases, synchronization mode for UEs may vary (e.g., in periodicity) based in part on the UE status, for example, idle or RRC connected mode. In some cases, the SFN may comprise a plurality of bits (e.g., <NUM> bits). Furthermore, a portion of those bits (e.g., <NUM> bits) may explicitly be a part of MIB, and the remainder (e.g., <NUM> bits) may be conveyed (e.g., implicitly) through PBCH. Thus, in some cases, a UE may utilize the <NUM> or <NUM> bit opportunistic information to decode the PBCH or determine the LSBs of the SFN, following which processing or decoding for the SFN may be optimized.

<FIG> illustrate example communications of a communications system including a transmitter <NUM>-a and a receiver <NUM>-b that support synchronization signal design. In some cases, the transmitter <NUM>-a and the receiver <NUM>-b may represent aspects of techniques performed by a base station <NUM> or a UE <NUM> as described with reference to <FIG>. As shown, transmitter <NUM>-a includes a sync signal sequence generator <NUM>, a precoding matrix generator <NUM>, a first antenna port <NUM>-a, and a second antenna port <NUM>-b. The receiver <NUM>-b includes a first antenna port <NUM>-a, a second antenna port <NUM>-b, a channel estimator <NUM>, a sequence detector <NUM>, and a channel estimation processor <NUM>. Each of the antenna ports <NUM> or <NUM> may be mapped to one or more antennas of the transmitter <NUM>-a or receiver <NUM>-b.

The sync signal sequence generator <NUM> may be used to generate a first synchronization signal and a second synchronization signal. In some examples, the first synchronization signal may be a PSS and the second synchronization signal may be an SSS. Once the first and second synchronization signals are generated, symbols associated with the first synchronization signal are mapped to antenna ports <NUM>-a and <NUM>-b. Similarly, the symbols associated with the second synchronization signal are also mapped to antenna ports <NUM>-a and <NUM>-b.

To map the symbols to the antenna ports <NUM>, a precoding matrix generated by the precoding matrix generator <NUM> may be used. The precoding matrix generator <NUM> may generate a different precoding matrix to map the symbols of the first and second synchronization signals for transmission by the antenna ports <NUM>-a and <NUM>-b. In some examples, a subset of tones used for transmission of the first synchronization signal and second synchronization signal may be configured to be transmitted using the same combined channel from the antenna ports <NUM> of the transmitter <NUM>-a. For instance, the precoding matrix may be used to map a synchronization signal to even tones. In some examples, the precoding matrix may be used to map a synchronization signal to the odd tones using a phase shift. Further, the choice of a second precoding matrix for the second synchronization signal <NUM>, when different from the first precoding matrix for the first synchronization signal <NUM>, may carry communication information.

For example, a <NUM> layer transmission in which transmitter <NUM>-a has two antenna ports <NUM>-a and <NUM>-b and receiver <NUM>-b has two antenna ports <NUM>-a and <NUM>-b. In some examples, the precoding matrix generator <NUM> may determine a precoding matrix for transmission of the first synchronization signal <NUM> and the second synchronization signal <NUM>. The choice of the precoding matrix may indicate additional communication information, which may be used by the receiver <NUM>-b to obtain the additional communication information to be used for cell acquisition, communication, or the like.

In one example, the channels for the first synchronization signal and the second synchronization signal observed by receiver <NUM>-b may be the same for even tones and different for odd tones. For instance, the first synchronization signal may be transmitted from all antenna ports <NUM> without precoding. Thus, the channel estimate equation for transmission of the first synchronization signal using antenna ports <NUM> may be defined as: <MAT>.

Referring now to <FIG>, in some examples, the SSS may be transmitted from first and second antenna ports of the transmitter <NUM>-a. As shown, transmitter <NUM>-a includes a first set of antenna ports <NUM>-a and a second set of antenna ports <NUM>-b. For even tones, the channel estimate for received SSS is the summation between H<NUM> and H<NUM>. The channel estimate for SSS signals for even ports is described in the following equation: <MAT>.

And, for odd tones, the received SSS signal is the difference between H<NUM> and H<NUM>. The channel estimate for SSS signals for odd ports is described in the following equation: <MAT>.

Therefore, when the UE <NUM> compares the channel between the PSS and the SSS on even tones, it expects to detect that the channel for the PSS is same as the channel for the SSS. When the UE <NUM> compares the channel between the PSS and the SSS on odd tones, it expects to detect that the channel for the PSS is different than the channel for the SSS. That is, the channel estimate for the PSS is the same (e.g., approximately equal) as the channel estimate for the SSS on even tones and the channel estimate for the PSS is different than the channel estimate for the SSS on odd tones. This may further be described using the following equations: <MAT> <MAT>.

In some examples, the SSS may be transmitted with a precoding matrix over even and odd tones. The SSS base sequence may be described as d and the SSS base sequence may be transmitted from <NUM>th tone to (N - <NUM>)th tone, where N describes the total number of tones occupied by an SSBlock. The base sequence for the SSS may be described as <MAT>. The SSS base sequence d may be transmitted using a precoding matrix <IMG>. In one example, the rows of the precoding matrix <IMG> may represent tones and the columns of the precoding matrix P may represent antenna ports. The precoding matrix P may be described as
<MAT>
In an example where the antenna port is <NUM> (i.e., even), the SSS base sequence may be <MAT> and represented by the following equation.

Where the antenna port is <NUM> (i.e., odd), the SSS base sequence may be <MAT> and represented by the following equation.

Based on the above, the SSS base sequence d transmitted from the Oth tone on an even port and the 1st tone on an even port may be d(<NUM>) shown by <NUM>-a and <NUM>-a. The SSS base sequence d transmitted from the Oth tone on an odd port may be d(<NUM>) <NUM>-b, while the SSS base sequence d transmitted from the 1st tone on an odd port, may be -d (<NUM>) <NUM>-b.

Further, the SSS base sequence d transmitted from the 2nd tone on an even port and the 3rd tone on an even port may be d(<NUM>) shown by <NUM>-a and <NUM>-a. The SSS base.

sequence d transmitted from the 2nd tone on an odd port may be d(<NUM>) <NUM>-b, while the SSS base sequence d transmitted from the 3rd tone on an odd port, may be -d(<NUM>) <NUM>-b. By comparing the base sequence received on sets of sub-carriers for a given port, the receiver <NUM>-b may determine a correlation between the SSS and the PSS and obtain additional communication information.

In some examples, the SSS base sequence may be received by the receiver <NUM>-b either from antenna port <NUM> or from antenna port <NUM>. The received SSS signal may be calculated using the following equation: <MAT>.

In some examples, the receiver <NUM>-b may be configured to determine the precoding matrix using the received PSS and the received SSS. In this example, the transmitter <NUM>-a may send <NUM> bit of information through the phase of the second synchronization signal by selecting a precoding matrix from one of the following:
<MAT>
where the rows in each of the precoding matrices map to different tones and the columns map to different antenna ports.

The receiver <NUM>-b may determine the precoding matrix used for transmission and therefore obtain the <NUM> bit of information by comparing the channel estimate for the received first synchronization signal and the channel estimate for the received second synchronization signal on even tones. The channel estimates may be determined by the channel estimator and using the channel estimates, the channel estimation processor may determine the addition information using the following:
<MAT>
was used
<MAT>
was used.

For instance, if the channel estimate for the received first synchronization signal is the same as the channel estimate for the received second synchronization signal, then the receiver <NUM>-b may determine that <IMG> was used as the precoding matrix. If the channel estimate for the received first synchronization signal is shifted by <NUM> degrees (i.e., inverted or phase shifted by π) when compared to the channel estimate for the received second synchronization signal, then the receiver <NUM>-b may determine that <IMG> was used as the precoding matrix.

In another example, the transmitter <NUM>-a may be configured to send <NUM> bits of information to the receiver <NUM>-b. The transmitter <NUM>-a may send <NUM> bit of information through the phase of the second synchronization signal and another bit of information through swapping a port mapping using the precoding matrix. In some examples, the transmitter <NUM>-a may have multiple choices for a precoding matrix, which may be different based on the port mapping. In one example, swapping the port mapping may involve generating a precoding matrix by using different phase relationships between antenna ports on various sets of tones. For instance, example precoding matrices are as follows:
<MAT>
where ai ∈ {<NUM>, -<NUM>}.

The receiver <NUM>-b may identify the precoding matrix by comparing the channel estimate of the first synchronization signal (e.g., PSS) over even tones with the channel estimate of the second synchronization signal (e.g., SSS) over even tones and the channel estimate of the first synchronization signal over odd tones with the channel estimate of the second synchronization signal over odd tones. In one example, the comparison is performed by the receiver <NUM>-b by comparing: <MAT>.

Over even and odd tones, the channel estimation for the first synchronization signal (e.g., PSS) may be calculated as a sum-channel and represented by the following equation: <MAT>.

During half of the tones, the channel estimation for the second synchronization signal (e.g., SSS) may be calculated as a delta-channel and represented by the following equation: <MAT>.

The channel estimation for the PSS and the channel estimation for the SSS are expected to match with <NUM> or π phase shift on half of the tones, and be different on the other half of the tones as represented by the following equations:
<MAT>
<MAT>
<MAT>
<MAT>.

For example, if the channel estimation for the PSS is equal to the channel estimation for the SSS on even tones, and the channel estimation for the PSS is not equal to the channel estimation for the SSS with <NUM> or π phase shift on odd tones, then the receiver <NUM>-b may determine that the precoding matrix used for transmission processing was <IMG>. In another example, if the channel estimation for the PSS is equal to the channel estimation for the SSS on odd tones, and the channel estimation for the PSS is not equal to the channel estimation for the SSS with <NUM> or π phase shift on even tones, then the receiver <NUM>-b may be able to calculate the precoding matrix as <IMG>. In another example, if the channel estimation for the PSS is equal to the negative of the channel estimation for the SSS on even tones, and the channel estimation for the PSS is not equal to the channel estimation for the SSS with <NUM> or π phase shift on odd tones, then the receiver <NUM>-b may be able to calculate the precoding matrix as <IMG>. In another example, if the channel estimation for the PSS is equal to the negative of the channel estimation for the SSS on odd tones, and the channel estimation for the PSS is not equal to the channel estimation for the SSS with <NUM> or π phase shift on even tones, then the receiver <NUM>-b may be able to calculate the precoding matrix as <IMG>.

In some examples, the second synchronization signal (e.g., SSS) may also be used for channel estimation of another signal such as a PBCH. For instance, the precoding matrix used during transmission of the SSS may determine the precoding matrix used during transmission of the PBCH. In some examples, during port swapping for the SSS, the transmitter <NUM>-a may generate a precoding matrix by swapping the rows for even tones with the rows for odd tones and thus, the transmission of the PBCH may also be based on the precoding matrix swapping the even tones with the odd tones. Further, the SSS may be a pilot signal for a PBCH.

In some examples, for PBCH, a Space-Frequency Block-Code (SFBC) matrix may be generated by transmitter <NUM>-a (e.g., using the precoding matrix generator <NUM>) for a particular precoding matrix <IMG>, which may be represented by the following precoding matrix <IMG> and PBCH SFBC matrix M:
<MAT>
<MAT>.

In some examples, the receiver <NUM>-b receives PBCH samples on two consecutive tones and the PBCH samples for even tones and odd tones may be calculated using the following equation: <MAT>.

The channel estimation for the SSS may be calculated by the using channel estimator <NUM> using the following equation: <MAT>.

An algorithm for estimating a channel at the receiver <NUM>-b may be based on the channel estimation for the SSS over even tones and the channel estimation for the SSS over odd tones. The receiver algorithm for channel estimation may be described using the following equation: <MAT>.

An algorithm for PBCH processing at the receiver <NUM>-b may be based on the channel estimates and the received PBCH over even tones and the channel estimates and the received PBCH over odd tones. The SFBC matrix M may be calculated using the PBCH processing algorithm using the following equation: <MAT>.

In some examples, transmitter <NUM>-a may change a precoding matrix <IMG> = <MAT> to another precoding matrix <MAT>. In some examples, precoding matrix <MAT> is chosen by swapping two ports and performing π rotation over the <NUM>nd port. If the precoding matrix is chosen to be <IMG>, then PBCH SFBC matrix correspondingly changes to <MAT> from <MAT> by swapping two ports and performing π rotation over the <NUM>nd port. The receiver <NUM>-b may receive PBCH samples on two consecutive tones. The calculation of received PBCH over even tones and odd tones may be based on following equation: <MAT>.

During even tones, the receiver <NUM>-b may receive SSS using H<NUM> - H<NUM>. During odd tones, the receiver <NUM>-b may receive SSS using -H<NUM> - H<NUM>. The calculation of the received SSS over even tones and odd tones is described in more details in the following equation: <MAT>.

The algorithm for estimating the channel at the receiver <NUM>-b may be based on the channel estimation for the SSS over even tones and the channel estimation for the SSS over odd tones. Using the receiver algorithm, the UE <NUM> may determine the value of H̃<NUM> as -H<NUM> and the value of H̃<NUM> as H<NUM>. The receiver algorithm for channel estimation may be described using the following equation: <MAT>.

In another example, the algorithm for PBCH processing at the receiver <NUM>-b may be based on the channel estimates and the received PBCH over even tones and the channel estimates and the received PBCH over odd tones. The SFBC matrix M may be calculated using the PBCH processing algorithm. The following example describes calculating the value of the SFBC matrix M using the PBCH processing algorithm for channel estimation using the following equation: <MAT>.

Thus, based on the above, regardless of the precoding matrix used for transmission by the transmitter <NUM>-a, the receiver <NUM>-b may be capable of receiving the correct samples.

<FIG> illustrates an example of a process flow <NUM> for synchronization signal design. Process flow <NUM> may include base station <NUM>-a and UE <NUM>-a, which may be examples of the corresponding devices described with reference to <FIG> and <FIG>.

At <NUM>, base station <NUM>-b may identify communication information associated with a cell. The identified communication information may indicate a physical channel timing parameter such as a synchronization periodicity or a PBCH periodicity (e.g., relative position of SSS within a frame, a redundancy version of PBCH), a beam sweep periodicity (e.g., an index of the SSBurst set within PBCH TTI), a CP type, etc. In some examples, the communication information may include a physical channel presence indicator that indicates the presence of a PBCH transmission, an MRS transmission, a beam or channel reference signal transmission, or combinations thereof. In some cases, the communication information may additionally or alternatively include a system information parameter, which may correspond to a cell ID, timing or frequency synchronization information, or other system information associated with the cell. For example, the system information parameter may be an indicator of an operation mode (e.g., initial acquisition, synchronization, or beam or mobility management, in an RRC-idle or RRC-connected mode) or DMRS configuration.

At <NUM>, base station <NUM>-b may establish a precoding relationship between a first synchronization signal (e.g., a PSS, a SSS, a DMRS, or a beam reference signal) and a second synchronization signal (e.g., a PSS, a SSS, a DMRS, or a beam reference signal). The precoding relationship may indicate or convey the communication information identified at <NUM>. In some examples, establishing the precoding relationship may include introducing a phase shift between the first synchronization signal and the second synchronization signal. The precoding relationship may additionally or alternatively indicate a precoding matrix for transmission of the first synchronization signal and/or the second synchronization signal.

At <NUM>, base station <NUM>-b may transmit at least one of the first synchronization signal and the second synchronization signal. The transmission may be performed based on the precoding relationship. For instance, the first synchronization signal may be transmitted having a phase shift with respect to the second synchronization signal. In some examples, the first and second synchronization signals may be transmitted using different precoding matrices. The first synchronization signal may be transmitted during a first set of resources (e.g., a first set of subcarriers, a first symbol period, or both) and the second synchronization signal may be transmitted during a second set of resources (e.g., a second set of subcarriers, a second symbol period, or both). In some examples, the base station <NUM>-b may transmit an SSBurst or SSBurst set that may include a plurality of SSBlocks. Different beamforming coefficients may be used to transmit the plurality of SSBlocks.

At <NUM>, based on the transmitted synchronization signals, the UE <NUM>-b may determine a first channel estimation for the first synchronization signal and a second channel estimation for the second synchronization signal. The channel estimation may be used to determine a channel correlation between the first synchronization signal and the second synchronization signal. In some instances, the channel estimation may be used to determine a phase shift between the first and second synchronization signals or a precoding matrix used during transmission of at least one of the first and second synchronization signals.

At <NUM>, UE <NUM>-b may obtain communication information (e.g., the communication information identified by base station <NUM>-b at <NUM>), further described with reference to <FIG>. Obtaining the communication information may be based at least in part on a channel correlation between the first channel estimation and the second channel estimation. In some examples, the UE <NUM>-b may determine first channel estimation difference based on a first set of sub-carriers or the UE <NUM>-b may determine a second channel estimation difference based on a second set of sub-carriers. Using the channel estimation difference or based on the channel correlation, the UE <NUM>-b may obtain one or more information bits corresponding to the communication information. At <NUM>, the UE <NUM>-b may communicate, with the base station <NUM>-b, based at least in part on the communication information.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports synchronization signal design in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a UE <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, UE synchronization 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 design, 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>.

UE synchronization manager <NUM> may receive a first synchronization signal during a first set of resources and a second synchronization signal during a second set of resources, the first and second synchronization signals associated with a cell. UE synchronization manager <NUM> may determine a first channel estimation for the first synchronization signal and a second channel estimation for the second synchronization signal. UE synchronization manager <NUM> may obtain communication information based on a channel correlation between the first channel estimation and the second channel estimation, and communicate, with a base station, based on the communication information. UE synchronization manager <NUM> may be an example of aspects of the UE synchronization manager <NUM> described with reference to <FIG>.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports synchronization signal design 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 UE <NUM> as described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, UE synchronization 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).

UE synchronization manager <NUM> may be an example of aspects of the UE synchronization manager <NUM> described with reference to <FIG>.

UE synchronization manager <NUM> may also include signal receiving component <NUM>, channel estimation component <NUM>, channel correlation component <NUM>, and communication component <NUM>.

Signal receiving component <NUM> may receive a first synchronization signal during a first set of resources and a second synchronization signal during a second set of resources, the first and second synchronization signals associated with a cell. In some cases, the first synchronization signal is a primary synchronization signal and the second synchronization signal is a secondary synchronization signal.

Channel estimation component <NUM> may determine a first channel estimation for the first synchronization signal and a second channel estimation for the second synchronization signal.

Channel correlation component <NUM> may obtain communication information based on a channel correlation between the first channel estimation and the second channel estimation. In some cases, the communication information indicates a physical channel timing parameter, a physical channel presence indicator, or a system information parameter. In some cases, the physical channel timing parameter includes an indicator of a synchronization periodicity or a PBCH periodicity (e.g., relative position of SSS within a frame, a redundancy version of PBCH), a beam sweep periodicity (e.g., an index of the SSBurst set within PBCH TTI), a CP type, or combinations thereof. In some cases, the physical channel presence indicator includes an indicator of any of a PBCH transmission, an MRS transmission, a beam or channel reference signal transmission, or combinations thereof.

Communication component <NUM> may communicate, with a base station, based on the communication information.

<FIG> shows a block diagram <NUM> of a UE synchronization manager <NUM> that supports synchronization signal design in accordance with various aspects of the present disclosure. The UE synchronization manager <NUM> may be an example of aspects of a UE synchronization manager <NUM>, a UE synchronization manager <NUM>, or a UE synchronization manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The UE synchronization manager <NUM> may include signal receiving component <NUM>, channel estimation component <NUM>, channel correlation component <NUM>, communication component <NUM>, phase shift component <NUM>, difference component <NUM>, precoding component <NUM>, and broadcast channel component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Phase shift component <NUM> may determine the communication information based on the phase shift. In some cases, the phase shift component <NUM> may determine a phase shift between the first synchronization signal and the second synchronization signal based on the first channel estimation and the second channel estimation on a set of sub-carriers.

Difference component <NUM> may determine a second channel estimation difference between the first channel estimation and the second channel estimation for a second set of sub-carriers and determine one or more information bits corresponding to the communication information based on the first and second channel estimation differences. In some cases, the difference component <NUM> may determine a first channel estimation difference between the first channel estimation and the second channel estimation for a first set of sub-carriers.

Precoding component <NUM> may determine a precoding matrix. In some cases, the precoding component <NUM> may determine the precoding matrix applied to transmission of the first synchronization signal and the second synchronization signal via a set of antenna ports. In some cases, the precoding component <NUM> may determine one or more information bits based at least in part on the precoding matrix.

Broadcast channel component <NUM> may demodulate a broadcast channel based on the first synchronization signal, the second synchronization signal, or a combination thereof.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports synchronization signal design 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 UE <NUM> as described above, e.g., 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 UE synchronization manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, and I/O controller <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 base stations <NUM>.

Processor <NUM> may include an intelligent hardware device, (e.g., a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), an field-programmable gate array (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 design).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support synchronization signal design. 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.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports synchronization signal design 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>. Wireless device <NUM> may include receiver <NUM>, base station synchronization 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).

Base station synchronization manager <NUM> may be an example of aspects of the base station synchronization manager <NUM> described with reference to <FIG>.

Base station synchronization manager <NUM> may identify communication information associated with a cell, establish a precoding relationship between a first synchronization signal and a second synchronization signal, the precoding relationship indicating the communication information, and transmit, based on the precoding relationship, the first synchronization signal during a first symbol period and the second synchronization signal during a second symbol period.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports synchronization signal design 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> as described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, base station synchronization 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).

Base station synchronization manager <NUM> may also include communication information identifier <NUM>, precoding relationship component <NUM>, and signal transmitting component <NUM>.

Communication information identifier <NUM> may identify communication information associated with a cell. In some cases, the communication information indicates a physical channel timing parameter, a physical channel presence indicator, or a system information parameter. In some cases, the physical channel timing parameter includes an indicator of any of a synchronization periodicity or a PBCH periodicity (e.g., relative position of SSS within a frame, a redundancy version of PBCH), a beam sweep periodicity (e.g., an index of the SSBurst set within PBCH TTI), a CP type, or combinations thereof. In some cases, the physical channel presence indicator includes an indicator of any of a PBCH transmission, an MRS transmission, a beam or channel reference signal transmission, or combinations thereof.

Precoding relationship component <NUM> may establish a precoding relationship between a first synchronization signal and a second synchronization signal, the precoding relationship indicating the communication information.

Signal transmitting component <NUM> may transmit, based on the precoding relationship, the first synchronization signal during a first set of resources and the second synchronization signal during a second set of resources. In some cases, the first synchronization signal is a primary synchronization signal and the second synchronization signal is a secondary synchronization signal.

<FIG> shows a block diagram <NUM> of a base station synchronization manager <NUM> that supports synchronization signal design in accordance with various aspects of the present disclosure. The base station synchronization manager <NUM> may be an example of aspects of a base station synchronization manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The base station synchronization manager <NUM> may include communication information identifier <NUM>, precoding relationship component <NUM>, signal transmitting component <NUM>, phase shift component <NUM>, precoding component <NUM>, beamforming component <NUM>, and broadcast channel component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Communication information identifier <NUM> may identify communication information associated with a cell. In some cases, the communication information indicates a physical channel timing parameter, a physical channel presence indicator, or a system information parameter. In some cases, the physical channel timing parameter includes an indicator of a synchronization periodicity or a PBCH periodicity (e.g., relative position of SSS within a frame, a redundancy version of PBCH), a beam sweep periodicity (e.g., an index of the SSBurst set within PBCH TTI), a CP type, or combinations thereof. In some cases, the physical channel presence indicator includes an indicator of any of a PBCH transmission, an MRS transmission, a beam or channel reference signal transmission, or combinations thereof.

Phase shift component <NUM> may transmit the PBCH during a third symbol period, based at least in part on the precoding relationship. In some cases, the phase shift component <NUM> may establish a phase shift between the first synchronization signal and the second synchronization signal. In some cases, the phase shift component <NUM> may transmit the first and second synchronization signals based on the phase shift. In some cases, the phase shift component <NUM> may establish a phase shift between the PBCH and either the first synchronization signal or the second synchronization signal.

Precoding component <NUM> may transmit the PBCH based at least in part on the precoding matrix. In some cases, the precoding component <NUM> may determine a precoding matrix for transmission of the first synchronization signal and the second synchronization signal via a set of antenna ports. In some cases, the precoding component <NUM> may transmit the first and second synchronization signals based at least in part on the precoding matrix. In some cases, the precoding component <NUM> may determine a precoding matrix for transmission of the PBCH via a set of antenna ports based on the channel correlation.

Beamforming component <NUM> may determine different beamforming coefficients. In some cases, the beamforming component <NUM> may transmit a set of synchronization signal blocks including the first synchronization signal and the second synchronization signal using one or more of the different beamforming coefficients.

Broadcast channel component <NUM> may transmit, based on the channel correlation, a PBCH during a third symbol period.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports synchronization signal design in accordance with various aspects of the present disclosure. Device <NUM> may be an example of or include the components of base station <NUM> as described above, e.g., with reference to <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including base station synchronization 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 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 design).

Base station communications manager <NUM> may manage communications with other base station <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>.

<FIG> shows a flowchart illustrating a method <NUM> for synchronization signal design in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a UE synchronization manager as described with reference to <FIG>. In some examples, a UE <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 UE <NUM> may perform aspects the functions described below using special-purpose hardware.

At block <NUM> the UE <NUM> receives a first synchronization signal during a first set of resources and a second synchronization signal during a second set of resources, the first and second synchronization signals associated with a cell. 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 signal receiving component as described with reference to <FIG>.

At block <NUM> the UE <NUM> determines a first channel estimation for the first synchronization signal and a second channel estimation for the second 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 channel estimation component as described with reference to <FIG>.

At block <NUM> the UE <NUM> obtains communication information based at least in part on a channel correlation between the first channel estimation and the second channel estimation. 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 channel correlation component as described with reference to <FIG>.

At block <NUM> the UE <NUM> communicates, with a base station, based at least in part on the communication information. 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 communication component as described with reference to <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for synchronization signal design 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 base station synchronization 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 of the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> may identify communication information associated with a cell. 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 communication information identifier as described with reference to <FIG>.

At block <NUM> the base station <NUM> may establish a precoding relationship between a first synchronization signal and a second synchronization signal, the precoding relationship indicating the communication information. 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 channel correlation component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit, based at least in part on the precoding relationship, the first synchronization signal during a first set of resources and the second synchronization signal during a second set of resources. 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 signal transmitting component as described with reference to <FIG>.

Techniques described herein may be used for various wireless communications systems such as CDMA, TDMA, FDMA, OFDMA, single carrier frequency division multiple access (SC-FDMA), and other systems. The terms "system" and "network" are often used interchangeably.

An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), 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). "3rd Generation Partnership Project" (3GPP) LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, NR, and GSM are described in documents from the organization named 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 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 geographic coverage area for a base station may be divided into sectors making up only a portion of the coverage area. The wireless communications system or systems described herein may include base stations of different types (e.g., macro or small cell base stations). The UEs described herein may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like. There may be overlapping geographic coverage areas for different technologies.

Also, as used herein, including in the claims, "or" as used in a list of items (for example, a list of items prefaced by a phrase such as "at least one of" or "one or more of') indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

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 for wireless communication performed by an apparatus, the method comprising:
receiving (<NUM>) a first synchronization signal during a first set of resources and
a second synchronization signal during a second set of resources, the first and second synchronization signals associated with a cell;
determining (<NUM>) a first channel estimation for the first synchronization signal and a second channel estimation for the second synchronization signal;
obtaining (<NUM>) communication information based at least in part on a channel correlation between the first channel estimation and the second channel estimation,
wherein the communication information indicates a physical channel timing parameter, a physical channel presence indicator, or a system information parameter,
and wherein obtaining the communication information comprises:
determining a first channel estimation difference between the first channel estimation and the second channel estimation for a first set of sub-carriers;
determining a second channel estimation difference between the first channel estimation and the second channel estimation for a second set of sub-carriers; and
determining one or more information bits corresponding to the communication information based at least in part on the first and second channel estimation differences; and
communicating (<NUM>), with a base station, based at least in part on the communication information.