SSB beam identification

Abstract

Example embodiments of the present disclosure provide a solution for synchronization signal block (SSB) beam identification In an example method, a network device transmits, to a terminal device, an SSB comprising at least one demodulation reference signal (DMRS). At least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB. After receiving the SSB, the terminal device determines an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

Description

SSB BEAM IDENTIFICATIONFIELD

[0001] Various example embodiments relate to the field of communication, and in particular, to devices, methods, apparatuses, and a computer readable medium for synchronization signal block (SSB) beam identification.BACKGROUND

[0002] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network.

[0003] Such communication networks operate in accordance with standards, such as those promulgated by 3 GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of such standards include the so-called 5G (5th Generation) standard or other standards promulgated by 3GPP.SUMMARY

[0004] In general, example embodiments of the present disclosure provide a solution for communication, especially for SSB beam identification. In this solution, there is provided a mechanism for a terminal device (such as user equipment (UE)) to identify an SSB beam. With this solution, the SSB index of the SSB beam is enabled to be determined based on new network information in case that the primary synchronization signal (PSS) / secondary synchronization signal (SSS) are decoupled from the PBCH / master information block (MIB) / system information block type 1 (SIB 1) within an SSB, for example, in the context of sixth generation (6G).

[0005] In a first aspect, there is provided a terminal device. The terminal device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to receive, from a network device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS); and determine an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0006] In a second aspect, there is provided a network device. The network device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to transmit, to a terminal device, an SSB comprising at least one DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0007] In a third aspect, there is provided a method. The method comprises: receiving, from a network device, an SSB comprising at least one DMRS; and determining an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0008] In a fourth aspect, there is provided a method. The method comprises: transmitting, to a terminal device, an SSB comprising at least one DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0009] In a fifth aspect, there is provided an apparatus. The apparatus comprises: means for receiving, from a network device, an SSB comprising at least one DMRS; and means for determining an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0010] In a sixth aspect, there is provided an apparatus. The apparatus comprises: means for transmitting, to a terminal device, an SSB comprising at least one DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0011] In a seventh aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least method of the above third aspect or fourth aspect.

[0012] In an eighth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform at least the method of the above third aspect or fourth aspect.

[0013] In a ninth aspect, there is provided a terminal device. The terminal device comprises: receiving circuitry configured to receive, from a network device, an SSB comprising at least one DMRS; and determining circuitry configured to determine an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0014] In a tenth aspect, there is provided a network device. The network device comprises: transmitting circuitry configured to transmit, to a terminal device, an SSB comprising at leastone DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0015] In an eleventh aspect, there is provided a terminal device. The terminal device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to receive, from a network device, an SSB comprising at least one physical broadcast channel (PBCH); and determine an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0016] In a twelfth aspect, there is provided a network device. The network device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to transmit, to a terminal device, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0017] In a thirteenth aspect, there is provided a method. The method comprises: receiving, from a network device, an SSB comprising at least one PBCH; and determining an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0018] In a fourteenth aspect, there is provided a method. The method comprises: transmitting, to a terminal device, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0019] In a fifteenth aspect, there is provided an apparatus. The apparatus comprises: means for receiving, from a network device, an SSB comprising at least one PBCH; and means for determining an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0020] In a sixteenth aspect, there is provided an apparatus. The apparatus comprises: means for transmitting, to a terminal device, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0021] In a seventeenth aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least method of the above third aspect or fourth aspect.

[0022] In an eighteenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform at least the method of the above third aspect or fourth aspect.

[0023] In a nineteenth aspect, there is provided a terminal device. The terminal device comprises: receiving circuitry configured to receive, from a network device, an SSB comprising at least one PBCH; and determining circuitry configured to determine an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0024] In a twentieth aspect, there is provided a network device. The network device comprises: transmitting circuitry configured to transmit, to a terminal device, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0025] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0027] FIG. 1A illustrates an example communication network in which embodiments of the present disclosure may be implemented;

[0028] FIG. IB illustrates the design of SSB in 5G;

[0029] FIG. 1C illustrates the location of the DMRS within the PBCH transmission in 5G;

[0030] FIG. 2 illustrates a flowchart illustrating an example process for SSB beam identification according to some embodiments of the present disclosure;

[0031] FIG. 3 illustrates a flowchart illustrating another example process for SSB beam identification according to some embodiments of the present disclosure;

[0032] FIG. 4 illustrates a signaling flow of an example embodiment according to some embodiments of the present disclosure;

[0033] FIG. 5 illustrates a signaling flow of another example embodiment according tosome embodiments of the present disclosure;

[0034] FIG. 6 illustrates a flowchart of an example method implemented at a terminal device according to some embodiments of the present disclosure;

[0035] FIG. 7 illustrates a flowchart of an example method implemented at a network device according to some embodiments of the present disclosure;

[0036] FIG. 8 illustrates a flowchart of another example method implemented at a terminal device according to some embodiments of the present disclosure;

[0037] FIG. 9 illustrates a flowchart of another example method implemented at a network device according to some embodiments of the present disclosure;

[0038] FIG. 10 illustrates a simplified block diagram of a device that is suitable for implementing some example embodiments of the present disclosure; and

[0039] FIG. 11 illustrates a block diagram of an example of a computer-readable medium in accordance with some example embodiments of the present disclosure.

[0040] Throughout the drawings, the same or similar reference numerals represent the same or similar elements.DETAILED DESCRIPTION

[0041] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

[0042] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0043] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure,or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0044] It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0046] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor s) or a portion of a microprocessor s), that requires software (for example, firmware) for operation, but the software may not be present when it is not needed for operation.

[0047] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0048] As used herein, the term “network”, “communication network” or “data network” refers to a network following any suitable communication standards, such as long-term evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), narrow band Internet of things (NB-IoT), wireless fidelity (Wi-Fi) and so on. Furthermore, the communications between a terminal device and a network device / element in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G), 4.5G, the fifth generation (5G), the future sixth generation (6G), IEEE 802.11 communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0049] As used herein, the term “network device” refers to a node in a communication network via which a terminal device receives services (e.g., positioning services) therefrom. The network device may refer to a core network device or access network device, such as base station (BS) or an access point (AP) or a transmission and reception point (TRP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a new radio (NR) NB (also referred to as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a WiFi device, a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. In the following description,the terms “network device”, “AP device”, “AP” and “access point” may be used interchangeably.

[0050] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), a station (STA) or station device, or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (for example, remote surgery), an industrial device and applications (for example, a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. In the following description, the terms “station”, “station device”, “STA”, “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0051] FIG. 1 A illustrates a schematic diagram of an example communication network 100 in which some embodiments of the present disclosure can be implemented. As shown in FIG. 1A, the communication network 100 may include terminal device 110 and network device 120. The network device 120 comprises at least one cell 130 to serve the terminal device 110.

[0052] It is to be understood that the number of network devices, terminal devices and cells is only for the purpose of illustration without suggesting any limitations. The communication network 100 may include any suitable number of network devices, terminal devices and cells adapted for implementing embodiments of the present disclosure.

[0053] Communications in the communication network 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the thirdgeneration (3G), the fourth generation (4G), the fifth generation (5G) and the sixth generation (6G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0054] 3GPP has developed network energy saving (NES)solutions in Releases 18 and 19 of 5G-Advanced (5G-A), but the MIB and PBCH (which carries the MIB) were not addressed due to the necessity of maintaining backwards compatibility for legacy devices. However, in the context of, for example, 6G, these back-compatibility constraints are eliminated, allowing for the conception of a completely new SSB / PBCH / MIB design.

[0055] The synchronization signal / PBCH block (also referred to as SS-block or SSB) in 5G NR comprises the primary synchronization signal (PSS), secondary synchronization signal (SSS), and the PBCH. Similar to LTE, NR defines two types of synchronization signals: the PSS and SSS.

[0056] Cell search is the procedure by which a terminal device (such as a user equipment (UE)) obtains time and frequency synchronization with a cell and identifies the physical cell identity (PCI) of the cell. This procedure may occur during various scenarios, such as when the terminal device is powered on, during mobility in connected mode, idle mode mobility (e.g., reselections), and inter-radio access technology (RAT) mobility to the NR system. To access the cell, the terminal device may utilize NR synchronization signals and PBCH to acquire the necessary information. The PCI of a cell can be determined by using the following equation:

[0057] The terminal device may determine the PCI group numberby using the SSS and the physical-layer identityby using the PSS. Additionally, the synchronization signals can be used by the terminal device for multiple purposes, including measurements for reference signal received power (RSRP) and reference signal receiving quality (RSRQ), aswell as beam management, and the like.

[0058] FIG. IB illustrates the design of SSB in 5G. As illustrated in FIG. IB, the SSB may include the PBCH which carries the MIB of the cell. It is worth noting that the PBCH may further convey supplementary information, including part of the system frame number (SFN) and the SSB subcarrier offset. The PSS, SSS, and PBCH are always grouped together within successive orthogonal frequency-division multiplexing (OFDM) symbols. In the time domain, an SS / PBCH block consists of 4 OFDM symbols, numbered in increasing order from 0 to 3 within the SS / PBCH block, where PSS, SSS, and PBCH with associated DMRS are mapped to symbols as given by Table 1 below (Table 7.4.3.1-1 in section 7.4.3 of TS 38.212).

[0059] In the frequency domain, an SS / PBCH block consists of 240 contiguous subcarriers (equivalent to 20 Resource Blocks (RBs), each RB may contain 12 subcarriers) with the subcarriers numbered in increasing order from 0 to 239 within the SS / PBCH block. The quantities k and I represent the frequency and time indices, respectively, within one SS / PBCH block. The terminal device may assume that the complex-valued symbols corresponding to resource elements denoted as 'Set to O' in Table 1 are set to zero. The quantity v in Table 1 is given by v = / Vfj1mod 4. The quantity fcSSBis the subcarrier offset from subcarrier 0 in common resource blockto the lowest-numbered subcarrier of the SS / PBCH block, or the SS / PBCH block after puncturing if applicable, whereis obtained from the higher-layer parameter offsetToPointA.

[0060] Table 1 below illustrates resources within an SS / PBCH block for PSS, SSS, PBCH, and DMRS for PBCH, according to 3GPP TS 38.212.Table 1 : Resources within an SS / PBCH block for PSS, SSS, PBCH, and DMRS for PBCH

[0061] One SSB burst (also referred to as an SSB burst set or an SSB set) may comprise one or more SSBs transmitted within a 5ms period of SSB transmissions. Within an SSB burst, each SSB is assigned a unique index, which may correspond to the beam in which the SSB was transmitted. The SSB index can be used by the terminal device for various purposes. For instance, during a random-access channel (RACH) procedure or initial access procedure, the terminal device may utilize the selected SSB index to map to a valid RACH occasion (RO). Similarly, when reporting the RSRP measurements, the terminal device may indicate the corresponding SSB index of the measurement.

[0062] The SSB index is a sequential number starting from 0 and incrementing by 1 for each SSB within the burst. This number may reset to 0 at the beginning of the next SSB burst, which may occur in the next 5ms after the completion of the SSB transmission cycle (e.g., 20ms). The SSB index can be communicated to the terminal device through two distinct components within the SSB. One part of the SSB index is carried by DMRS for PBCH and another part is carried by the PBCH payload.

[0063] According to 3 GPP specification, within a half-frame, the candidate SS / PBCH blocks are indexed sequentially from 0 to L-l (which represents the number of candidate SSBs). For L = 4, the terminal device may determine the 2 LSB bits of the SS / PBCH block index per half-frame via a one-to-one mapping with the index of the DMRS sequence transmitted in the PBCH. For L > 4, this extends to 3 LSB bits. Specifically, for L = 64, the terminal device may determine the 3 MSB bits of the SS / PBCH block index per half-frame through the PBCH payload bits.

[0064] DMRS may help the terminal device to accurately decode radio channels from different channels such PBCH. FIG. 1C illustrates the location of the DMRS within the PBCH transmission in 5G. As illustrated in FIG. 1C, the DMRS for PBCH will be available in symbols 1, 2, and 3, and will be assigned every fourth resource element (RE) based on PCI mod 4, occupying 25% of PBCH resources, as shown in Table 1 above. Specifically, in symbols 1 and 3, it occupies 60 REs (calculated as 240 total REs divided by 4). In symbol 2, it occupies 24 REs (calculated as total 96 REs (12 subcarriers multiplied by 8 Physical Resource Blocks (PRBs)) divided by 4).

[0065] According to Table 1 (Table 7.4.3.1-1 in section 7.4.3 of TS 38.212), the OFDM symbol numbers may be corresponding to their respective subcarrier numbers for each channel or signal. For example, the PSS is mapped to OFDM symbol number 0 and subcarriernumbers 56, 57, ..., 182; the SSS is mapped to OFDM symbol number 2 and the same subcarrier range as PSS; and the DMRS for PBCH is mapped to OFDM symbol numbers 1 and 3, with its subcarrier number ranging from 0+v to 44+v, and 192+v to 239+v, including a pattern that changes with the physical cell ID.

[0066] This indicates that the location of the PBCH DMRS moves along the frequency domain as the PCI changes. The variable “v” in the DMRS resource mapping can be calculated as a function of the PCI modulo 4.

[0067] In another aspects, the payload size of the PBCH, inclusive of a 24-bit CRC, totals 56 bits. Table 2 below provides an overview of the number of bits occupied by the information / field within the PBCH / MIB.Table 2: The number of bits occupied by the information / field within the PBCH / MIB

[0068] As shown in Table 2, the SSB index (0 or 3 bits) is not conveyed through the MIB; instead, the PBCH payload includes the required 3 bits for FR2. The index indicating a specific SSB within an SSB burst set is crucial for achieving frame synchronization. The maximum number of candidate SSBs (Lmax) within an SS burst set varies based on the carrier frequency. By way of example, for sub-6 GHz frequencies (Lmax= 8), each of the 8 PBCH scrambling sequences (section 7.3.3.1 of TS 38.211) used for PBCH scrambling implicitly indicates one of the 8 SSB indices. In this case, no explicit bits are required to indicate the SSB index. For frequencies above 6 GHz (Lmax= 64), each of the 8 PBCH scrambling sequences (section 7.3.3.1 of TS 38.211) used for PBCH scrambling implicitly indicates the 3 least significant bits (LSB) of the SSB index. To represent all 64 SSB indices, an additional 3 bits (most significant bits, MSB) are required and are explicitly carried within the PBCH payload.

[0069] In the SSB design of 5G NR, as illustrated in Figure IB, the SSB comprises PSS, SSS, and PBCH, all of which may be transmitted when SSB is transmitted. In this case, once the terminal device has read the PBCH and its contained MIB, for example, to acquire the scheduling information for SIB1, there is no need for the terminal device to re-read the MIB. However, for mobility and synchronization purposes, the terminal device may need to periodically receive the SSB to measure the PSS or the SSS. Typically, in such scenarios, the terminal device may ignore the MIB payload within the PBCH and maybe even the entire PBCH payload.

[0070] Multiple concepts for 6G have been proposed to separate / decouple the transmission of synchronization signals (PSS / SSS) from the transmission of PBCH / MIB, aiming to optimize the energy consumption for network and the terminal device and to reduce signaling overhead. For instance, in some solutions, it is suggested to operate PSS / SSS with a shorter periodicity and PBCH / MIB (which schedules SIB1) with a longer periodicity. These solutions allow the network to transmit PBCH / MIB less frequently than PSS / SSS, enabling an energy saving mechanism: the network device (such as gNB) can enter microsleep mode during the symbols #1 and #3 of an SSB (i.e. 50% of the SSB time duration), where PBCH would usually be sent when PBCH and PSS / SSS have the same periodicity. Additionally, SIB1 (repetition) transmissions can follow the PBCH / MIB transmission periodicity.

[0071] However, as previously mentioned, the terminal device may need to determine the SSB beam index (also referred to as “SSB index” elsewhere in this description) from thereceived SSB for various operational purposes. In some instances, the terminal device may determine the SSB index by identifying the beam number of the SSB beam. Crucially, this index is utilized by the terminal device to determine basic timing information for time synchronization, including determining the frame boundary based on the 3 -bit MSB of the SSB index information element (IE) and the 1 -bit half-frame index IE present in the PBCH payload. Moreover, the terminal device may select a RACH occasion (RO) corresponding to the selected SSB beam, for example, the strongest beam received by the terminal device. This selection is guided by the “RO to SSB beam mapping” specified in the standard. Consequently, when the network device receives a PRACH preamble in a specific RO, it can determine the appropriate SSB beam to be used for responding to the terminal device based on this defined mapping where the beam may be identified based on the SSB index. Furthermore, the terminal device may perform L3 / L1-RSRP measurements for each SSB beam and submit the measurement reports to the network device, indicating both the RSRP value and the corresponding SSB beam.

[0072] Currently, the determination of the SSB beam by the terminal device relies on the DMRS associated with the PBCH when up to 8 SSB beams are used, and on both the PBCH DMRS and PBCH payload when more than 8 SSB beams are used. However, in scenarios where the PBCH and its associated DMRS are removed from certain SSB occurrences, a challenge arises regarding how the terminal device identifies the SSB beam index in those SSB occurrences, given that the current method of SSB beam identification cannot be applied.

[0073] According to some embodiments of the present disclosure, there is provided a solution for a terminal device (such as UE) to identify an SSB beam. With this solution, the SSB index of the SSB beam is enabled to be determined based on new network information in case that the PSS / SSS are decoupled from the PBCH / MIB / SIB1 within an SSB, for example, in the context of 6G.

[0074] FIG. 2 illustrates a flowchart illustrating an example process 200 for SSB beam identification according to some embodiments of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to FIG. 1A. The process 200 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1 A. It would be also appreciated that although the process 200 for link has been described in the communication network 100 of FIG. 1A, this process may be likewise applied to other communication scenarios where different network devices are jointly deployed to provide respective services.

[0075] As shown in FIG. 2, at 212, the network device 120 may transmit, to a terminal device 110, a synchronization signal block (SSB) 214 comprising at least one DMRS. In the SSB 214, at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0076] In some embodiments, the at least one frequency location may comprise a frequency offset value (also referred to as frequency shift value) of the at least one DMRS from a reference frequency location. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSB beams. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,Jerepresents a physical cell identifier (PCI) of a cell of the network device, Lmaxrepresents the max number of the SSBs (i.e. maximum number of SSB beams), and SSBJndex represents the SSB index of the SSB.

[0077] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB. For example, the frequency location of a PSS / SSS can be the first subcarrier of the PSS / SSS, the center subcarrier of the PSS / SSS, or the last subcarrier of the PSS / SSS.

[0078] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs) in frequency domain. In these embodiments, the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0079] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0080] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one DMRS.

[0081] In some embodiments, the at least one DMRS may be in at least one symbol (suchas symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0082] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be transmitted in cases where the legacy PBCH is not present.

[0083] Then, upon receiving the SSB 214 at 216, at 220, the terminal device 110 may determine an SSB index of the SSB based on at least one frequency location of the at least one DMRS. In some embodiments, the determined SSB index may be applied to various operations, for example, time synchronization, selection of valid RACH occasion (RO), or the like.

[0084] FIG. 3 illustrates a flowchart illustrating another example process 300 for SSB beam identification according to some embodiments of the present disclosure. For the purpose of discussion, the process 300 will be described with reference to FIG. 1A. The process 300 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1 A. It would be also appreciated that although the process 300 for link has been described in the communication network 100 of FIG. 1A, this process may be likewise applied to other communication scenarios where different network devices are jointly deployed to provide respective services.

[0085] As shown in FIG. 3, at 312, the network device 120 may transmit, to a terminal device 110, an SSB 214 comprising at least one PBCH. In these embodiments, at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0086] In some embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. It is noted that, the term “start of the SSB” here may be understood as referring to either the first subcarrier of the PSS / SSS, or the first subcarrier set to zero of the first symbol. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB — Index mod Lm / I t-nL rr'V wherein k represents the start subcarrier number, Lmaxrepresents the max number of theSSBs (i.e. maximum number of SSB beams), and SSBJndex represents the SSB index of the SSB.

[0087] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one PBCH in the SSB.

[0088] Then, upon receiving the SSB 314 at 316, at 320, the terminal device 110 may determine an SSB index of the SSB based on at least one frequency location of the at least one PBCH. In some embodiments, the determined SSB index may be applied to various operations, for example, time synchronization, selection of valid RACH occasion (RO), or the like.

[0089] The present disclosure proposes network signaling (between the serving cell and the terminal device) and behaviors of the terminal device that allows the terminal device to determine the SSB index based on either the PBCH DMRS frequency location or the PBCH frequency location. This solution can be applicable in scenarios where the PSS and SSS are decoupled from PBCH / MIB / SIB1 transmissions, such as in the 6G radio interface. Furthermore, the PSS and SSS may also change in terms of time position, frequency position and bandwidth, but the SSB index may still be determined based on either the PBCH DMRS frequency location or the PBCH frequency location. The terminal device can utilize the determined SSB index in various operations as needed.

[0090] Specifically, the present disclosure provides two options. In the first option, the SSB beam index information can be implicit signaled via a (PBCH) DMRS frequency location. In each SSB occurrence, the SSB can incorporate at least the PBCH DMRS, which implicitly indicates the SSB index. Even if the PBCH itself is not transmitted, the PBCH DMRS is still transmitted alongside the PSS / SSS. Subsequently, the terminal device may determine the SSB index of a particular SSB occurrence based on information derived from the DMRS.

[0091] The PBCH DMRS frequency location can change with the SSB index, for example, by applying a modulo operation. The DMRS locations defined in Table 1 (Table 7.4.3.1-1 in section 7.4.3 of TS 38.212) can be modified based on the following equation:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device, Lmaxrepresents the max number of SSBs, and SSBJndex represents theSSB index of the SSB.

[0092] In some embodiments, the terminal device may firstly determine the frequency locations of the PSS and SSS which for example will start in subcarrier 56. Then the terminal device may determine the location the first DMRS, for example, in subcarrier 0, 1, 2, 4, etc. In some embodiments, assuming Lmax= 8, then the DMRS associated with SSB index = 0 may start at subcarrier number 0; the DMRS associated with SSB index = 1 may start at subcarrier number 8; the DMRS associated with SSB index = 2 may start at subcarrier number 16, and so forth.

[0093] In such embodiments, the time / frequency location of the DMRS can be further optimized either as an alternative or as a complement to the aforementioned embodiments. For the frequency-domain allocation of DMRS, in some embodiments under the context of 5G, DMRSs for the PBCH may be interleaved with the PBCH, specifically every fourth RE of the PBCH. However, in some other embodiments, DMRSs can be transmitted in contiguous REs in frequency domain, with the utilized REs indicating the SSB index based on specified mapping configuration or information.

[0094] Additionally, if the primary purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0095] For the time-domain allocation of DMRS, in some embodiments, aiming to minimize network transmission times, the DMRSs can be transmitted only in symbols 0 and 2 of the SSB, which align with the PSS and SSS transmissions. Alternatively, in some embodiments, the DMRSs can be transmitted only in symbol 2 of the SSB, which align with the SSS transmissions. Alternatively, in some embodiments, the DMRSs can be transmitted in only one symbol of the SSB, such as symbol 0, 1, 2, or 3.

[0096] In some embodiments, the DMRSs can be are transmitted even in cases where the legacy PBCH is not present.

[0097] FIG. 4 illustrates a signaling flow 400 of an example embodiment according to some embodiments of the present disclosure. In FIG. 4, the SSB index can be implicitly signaled to the terminal device based on (PBCH) DMRS frequency location. For the purpose of discussion, the signaling flow 400 will be described with reference to FIG. 1 A. The signaling flow 400 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1 A. It would be also appreciated that although the signaling flow 400 for link has been described in the communication network 100 of FIG. 1 A, this signaling flow may be likewiseapplied to other communication scenarios where different network devices are jointly deployed to provide respective services.

[0098] As illustrated in FIG. 4, at 410, the terminal device 110 can operate in various modes, including Radio Resource Control (RRC) idle mode, RRC inactive mode, or RRC connected mode. At 420, the network device 120 may transmit an SS / PBCH block (SSB) comprising PSS / SSS and DMRS including an SSB index indication.

[0099] After receiving the SSB from the network device 120, at 430, the terminal device 110 may determine the SSB index based on a frequency resource location of the DMRS. In some embodiments, the SSB index may be determined further based on a time resource location of the DMRS

[0100] Then, at 440, the terminal device 110 may apply the determined SSB index in some required operations, for example, time synchronization, selection of valid RACH occasion (RO), or the like.

[0101] Alternatively, in the second option of the present disclosure, the SSB beam index information can be implicit signaled via a PBCH frequency location. In each SSB occurrence, the SSB may incorporate at least the PBCH, which may not include the MIB payload. In this case, the frequency location of the PBCH may indicate implicitly the SSB index. Subsequently, the terminal device may determine the SSB index of a particular SSB occurrence based on information derived from the frequency location of the PBCH, for example, a start frequency location of the PBCH.

[0102] The PBCH frequency location can change with the SSB index, for example, by applying a modulo operation. The PBCH locations defined in Table 1 (Table 7.4.3.1-1 in section 7.4.3 of TS 38.212) can be modified based on the following equation: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0103] In some embodiments, assuming the maximum number of SSBs (Lmax) is 8, then the PBCH associated with SSB index = 0 may start at subcarrier number 0; the PBCH associated with SSB index = 1 may start at subcarrier number 8; the PBCH associated with SSB index = 2 may start at subcarrier number 16, and so forth.

[0104] FIG. 5 illustrates a signaling flow 500 of another example embodiment according tosome embodiments of the present disclosure. In FIG. 5, the SSB index can be implicitly signaled to the terminal device based on PBCH frequency location. For the purpose of discussion, the signaling flow 500 will be described with reference to FIG. 1 A. The signaling flow 500 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1 A. It would be also appreciated that although the signaling flow 500 for link has been described in the communication network 100 of FIG. 1A, this signaling flow may be likewise applied to other communication scenarios where different network devices are jointly deployed to provide respective services.

[0105] As illustrated in FIG. 5, at 510, the terminal device 110 can operate in various modes, including Radio Resource Control (RRC) idle mode, RRC inactive mode, or RRC connected mode. At 520, the network device 120 may transmit an SS / PBCH block (SSB) comprising PSS / SSS and PBCH including an SSB index indication.

[0106] After receiving the SSB from the network device 120, at 530, the terminal device 110 may determine the SSB index based on a frequency resource location of the PBCH. In some embodiments, the SSB index may be determined further based on a time resource location of the PBCH

[0107] Then, at 540, the terminal device 110 may apply the determined SSB index in some required operations, for example, time synchronization, selection of valid RACH occasion (RO), or the like.

[0108] It is noted that, the first and second options of the present disclosure can be used in combination to indicate all the SSB indices, especially when Lmaxis larger than 8.

[0109] In summary, some embodiments of the present disclosure herein provide a solution for a terminal device (such as UE) to identify an SSB beam. With this solution, the SSB index of the SSB beam is enabled to be determined based on new network information in case that the PSS / SSS are decoupled from the PBCH / MIB / SIB1 within an SSB, for example, in the context of 6G. In addition, since the PBCH frequency location is adjusted with an offset based on the SSB index, there is no need to alter the PSS / SSS frequency location, therefore the detection of PSS / SSS can be simplified.

[0110] FIG. 6 illustrates a flowchart of an example method 600 implemented at a terminal device according to some embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the terminal device 110 with reference to FIG. 1 A.

[0111] At block 610, the terminal device 110 may receive, from a network device 120, an SSB comprising at least one DMRS. Then, at block 620, the terminal device 110 may determine an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0112] In some embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device 120, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device 120, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0113] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0114] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs). In such embodiments, the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0115] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0116] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one DMRS.

[0117] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a thirdsymbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0118] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0119] Alternatively, in some embodiments, the SSB index of the SSB may be determined further based on at least one frequency location of at least one PBCH in the SSB. In such embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0120] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one PBCH in the SSB.

[0121] FIG. 7 illustrates a flowchart of an example method 700 implemented at a network device according to some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the network device 120 with reference to FIG. 1 A.

[0122] At block 710, the network device 120 may transmit, to a terminal device 110, an SSB comprising at least one DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0123] In some embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the frequency offset value may indicate the SSB index of the SSB based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,^11represents a PCI of a cell of the network device 120, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0124] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0125] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0126] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0127] In some embodiments, at least one time location of the at least one DMRS may further be used for indicating the SSB index of the SSB.

[0128] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0129] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0130] Alternatively, in some embodiments, at least one frequency location of at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB. In such embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the start subcarrier number may indicate the SSB index of the SSB based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:k = SSB — Index mod Lm / Inrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0131] In some embodiments, at least one time location of the at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB.

[0132] FIG. 8 illustrates a flowchart of an example method 800 implemented at a terminal device according to some embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the terminal device 110 with reference to FIG. 1 A.

[0133] At block 810, the terminal device 110 may receive, from a network device 120, an SSB comprising at least one PBCH. Then, at block 820, the terminal device 110 may determine an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0134] In some embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0135] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one PBCH in the SSB.

[0136] Alternatively, in some embodiments, the SSB index of the SSB may be determined further based on at least one frequency location of at least one DMRS.

[0137] In such embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device 120, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on thefollowing equations:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device 120, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0138] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0139] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0140] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0141] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one DMRS.

[0142] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0143] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0144] FIG. 9 illustrates a flowchart of an example method 900 implemented at a network device according to some embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the network device 120 with reference to FIG. 1 A.

[0145] At block 910, the network device 120 may transmit, to a terminal device 110, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0146] In some embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the start subcarrier number may indicate the SSB index of the SSB based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0147] In some embodiments, at least one time location of the at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB.

[0148] Alternatively, in some embodiments, at least one frequency location of at least one DMRS in the SSB may further be used for indicating the SSB index of the SSB.

[0149] In such embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the frequency offset value may indicate the SSB index of the SSB based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device 120, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device 120, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0150] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0151] In some embodiments, the at least one DMRS may be located in contiguous resourceelements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0152] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0153] In some embodiments, at least one time location of the at least one DMRS may further be used for indicating the SSB index of the SSB.

[0154] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0155] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0156] In some embodiments, an apparatus capable of performing any of the method 600 (for example, the terminal device 110) may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0157] In some embodiments, the apparatus may comprise means for receiving, from a network device, an SSB comprising at least one DMRS; and means for determining an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

[0158] In some embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,^11represents a PCI of a cell of the network device, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0159] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0160] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0161] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0162] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one DMRS.

[0163] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0164] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0165] Alternatively, in some embodiments, the SSB index of the SSB may be determined further based on at least one frequency location of at least one PBCH in the SSB. In such embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:k = SSB — Index mod Lm / Inrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0166] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one PBCH in the SSB.

[0167] In some embodiments, the apparatus may further comprise means for performing other steps of some embodiments of method 600. In some embodiments, the means may comprise at least one processor and at least one memory comprising computer program code, wherein the at least one memory and computer program code are configured with the at least one processor to cause the performance of the apparatus.

[0168] In some embodiments, an apparatus capable of performing any of the method 700 (for example, the network device 120) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0169] In some embodiments, the apparatus may comprise means for transmitting, to a terminal device, an SSB comprising at least one DMRS, wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

[0170] In some embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the frequency offset value may indicate the SSB index of the SSB based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0171] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0172] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0173] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0174] In some embodiments, at least one time location of the at least one DMRS may further be used for indicating the SSB index of the SSB.

[0175] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0176] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0177] Alternatively, in some embodiments, at least one frequency location of at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB. In such embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the start subcarrier number may indicate the SSB index of the SSB based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0178] In some embodiments, at least one time location of the at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB.

[0179] In some embodiments, the apparatus may further comprise means for performingother steps of some embodiments of method 700. In some embodiments, the means may comprise at least one processor and at least one memory comprising computer program code, wherein the at least one memory and computer program code are configured with the at least one processor to cause the performance of the apparatus.

[0180] In some embodiments, an apparatus capable of performing any of the method 800 (for example, the terminal device 110) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0181] In some embodiments, the apparatus may comprise means for receiving, from a network device, an SSB comprising at least one PBCH; and means for determining an SSB index of the SSB based on at least one frequency location of the at least one PBCH in the SSB.

[0182] In some embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0183] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one PBCH in the SSB.

[0184] Alternatively, in some embodiments, the SSB index of the SSB may be determined further based on at least one frequency location of at least one DMRS.

[0185] In such embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the SSB index of the SSB may be determined based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,^11represents a PCI of a cell of the network device, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0186] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determined based on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0187] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0188] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0189] In some embodiments, the SSB index of the SSB may be determined further based on at least one time location of the at least one DMRS.

[0190] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0191] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0192] In some embodiments, the apparatus may further comprise means for performing other steps of some embodiments of method 800. In some embodiments, the means may comprise at least one processor and at least one memory comprising computer program code, wherein the at least one memory and computer program code are configured with the at least one processor to cause the performance of the apparatus.

[0193] In some embodiments, an apparatus capable of performing any of the method 900(for example, the network device 120) may comprise means for performing the respective steps of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0194] In some embodiments, the apparatus may comprise means for transmitting, to a terminal device, an SSB comprising at least one PBCH, wherein at least one frequency location of the at least one PBCH is used for indicating an SSB index of the SSB.

[0195] In some embodiments, the at least one frequency location of the at least one PBCH may comprise a start subcarrier number of the at least one PBCH relative to a start of the SSB. In such embodiments, the start subcarrier number may indicate the SSB index of the SSB based on a modulo operation related to the start subcarrier number and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations: k = SSB Index mod Lmnrwherein k represents the start subcarrier number, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0196] In some embodiments, at least one time location of the at least one PBCH in the SSB may further be used for indicating the SSB index of the SSB.

[0197] Alternatively, in some embodiments, at least one frequency location of at least one DMRS in the SSB may further be used for indicating the SSB index of the SSB.

[0198] In such embodiments, the at least one frequency location may be associated with a frequency offset value of the at least one DMRS from a reference frequency location. In such embodiments, the frequency offset value may indicate the SSB index of the SSB based on a modulo operation related to the frequency offset value, a PCI of a cell of the network device, and a max number of SSBs. For example, the SSB index of the SSB can be determined based on the following equations:wherein v represents the frequency offset value, N,Jel1represents a PCI of a cell of the network device, Lmaxrepresents the max number of SSBs, and SSBJndex represents the SSB index of the SSB.

[0199] In such embodiments, the reference frequency location can be predetermined. Alternatively, in such embodiments, the reference frequency location can be determinedbased on a frequency location of a PSS in the SSB or a frequency location of an SSS in the SSB.

[0200] In some embodiments, the at least one DMRS may be located in contiguous resource elements (REs), wherein the contiguous REs can be used for indicating the SSB index based on, for example, specified mapping configuration or information.

[0201] In some embodiments, the number of REs for the at least one DMRS may be less than a predetermined value. For example, if the main purpose of the DMRS is to convey specific information, such as the SSB index (and potentially the MIB / PBCH periodicity), the number of REs allocated to DMRSs can be reduced compared to the legacy usage (60 REs + 24 REs).

[0202] In some embodiments, at least one time location of the at least one DMRS may further be used for indicating the SSB index of the SSB.

[0203] In some embodiments, the at least one DMRS may be in at least one symbol (such as symbol 0, 1, 2, or 3) of the SSB. In such embodiments, the at least one DMRS may be in either a first symbol (i.e. symbol 0) of the SSB coincide with PSS transmission or a third symbol (i.e. symbol 2) of the SSB coincide with SSS transmission in the SSB. Alternatively, the at least one DMRS may be in both a first symbol of the SSB coincide with PSS transmission or a third symbol of the SSB coincide with SSS transmission in the SSB.

[0204] In some embodiments, the SSB may not include any PBCH, which means that the DMRSs can be are transmitted in cases where the legacy PBCH is not present.

[0205] In some embodiments, the apparatus may further comprise means for performing other steps of some embodiments of method 900. In some embodiments, the means may comprise at least one processor and at least one memory comprising computer program code, wherein the at least one memory and computer program code are configured with the at least one processor to cause the performance of the apparatus.

[0206] FIG. 10 illustrates a simplified block diagram of a device 1000 that is suitable for implementing some example embodiments of the present disclosure.

[0207] The device 1000 may be provided to implement the communication device, for example the terminal device 110 and the network device 120 as shown in FIG. 1 A. As shown, the device 1000 includes one or more processors 1010, one or more memories 1020 coupled to the processor 1010, and one or more communication modules 1040 coupled to theprocessor 1010.

[0208] The communication module 1040 is for bidirectional communications. The communication module 1040 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

[0209] The processor 1010 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1000 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0210] The memory 1020 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1024, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 1022 and other volatile memories that will not last in the power-down duration.

[0211] A computer program 1030 includes computer executable instructions that are executed by the associated processor 1010. The program 1030 may be stored in the ROM 1024. The processor 1010 may perform any suitable actions and processing by loading the program 1030 into the RAM 1022.

[0212] The embodiments of the present disclosure may be implemented by means of the program 1030 so that the device 1000 may perform any process of the disclosure as discussed with reference to FIGS. 6 to 9. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0213] In some embodiments, the program 1030 may be tangibly contained in a computer readable medium which may be included in the device 1000 (such as in the memory 1020) or other storage devices that are accessible by the device 1000. The device 1000 may load the program 1030 from the computer readable medium to the RAM 1022 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

[0214] FIG. 11 illustrates a block diagram of an example of a computer-readable medium 1000 in accordance with some example embodiments of the present disclosure.

[0215] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0216] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods 600 to 900 as described above with reference to FIGS. 6 to 9. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0217] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0218] In the context of the present disclosure, the computer program codes or related datamay be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0219] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0220] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0221] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A terminal device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: receive, from a network device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS); and determine an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

2. The terminal device of claim 1, wherein the at least one frequency location is associated with a frequency offset value of the at least one DMRS from a reference frequency location.

3. The terminal device of claim 2, wherein the SSB index of the SSB is determined based on a modulo operation for the following: the frequency offset value; a physical cell identifier (PCI) of a cell of the network device; and a max number of SSBs.

4. The terminal device of claim 2 or 3, wherein the reference frequency location is predetermined.

5. The terminal device of claim 2 or 3, wherein the reference frequency location is determined based on: a frequency location of a primary synchronization signal (PSS) in the SSB; or a frequency location of a secondary synchronization signal (SSS) in the SSB.

6. The terminal device of any of claims 1 to 5, wherein the at least one DMRS is located in contiguous resource elements (REs), wherein the contiguous REs are used for indicating the SSB index.

7. The terminal device of any of claims 1 to 6, wherein a number of REs for the at least one DMRS is less than a predetermined value.

8. The terminal device of any of claims 1 to 7, wherein the SSB index of the SSB is determined further based on at least one time location of the at least one DMRS.

9. The terminal device of any of claims 1 to 8, wherein the at least one DMRS is in at least one symbol of the SSB.

10. The terminal device of claim 9, wherein the at least one DMRS is in at least one of the following: a first symbol of the SSB coincide with PSS transmission; and a third symbol of the SSB coincide with SSS transmission.

11. The terminal device of any of claims 1 to 10, wherein the SSB does not include a physical broadcast channel (PBCH).

12. The terminal device of any of claims 1 to 10, wherein the SSB index of the SSB is determined further based on at least one frequency location of at least one PBCH in the SSB.

13. The terminal device of claim 12, wherein the at least one frequency location of the at least one PBCH comprises a start subcarrier number of the at least one PBCH relative to a start of the SSB.

14. The terminal device of claim 13, wherein the SSB index of the SSB is determined based on a modulo operation for the following: the start subcarrier number; and a max number of SSBs.

15. The terminal device of any of claims 12 to 14, wherein the SSB index of the SSB is determined further based on at least one time location of the at least one PBCH in the SSB.

16. A network device comprising:39at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a terminal device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS), wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

17. The network device of claim 16, wherein the at least one frequency location is associated with a frequency offset value of the at least one DMRS from a reference frequency location.

18. The network device of claim 17, wherein the frequency offset value indicates the SSB index of the SSB based on a modulo operation for the following: the frequency offset value; a physical cell identifier (PCI) of a cell of the network device; and a max number of SSBs.

19. The network device of claim 17 or 18, wherein the reference frequency location is predetermined.

20. The network device of claim 17 or 18, wherein the reference frequency location is determined based on: a frequency location of a primary synchronization signal (PSS) in the SSB; or a frequency location of a secondary synchronization signal (SSS) in the SSB.

21. The network device of any of claims 16 to 20, wherein at least one DMRS is located in contiguous resource elements (REs), wherein the contiguous REs are used for indicating the SSB index.

22. The network device of any of claims 16 to 20, wherein a number of REs for the at least one DMRS is less than a predetermined value.

23. The network device of any of claims 16 to 22, wherein at least one time location of the at least one DMRS is further used for indicating the SSB index of the SSB.4024. The network device of any of claims 16 to 23, wherein the at least one DMRS is in at least one symbol of the SSB.

25. The network device of claim 24, wherein the at least one DMRS is in at least one of the following: a first symbol of the SSB coincide with PSS transmission; and a third symbol of the SSB coincide with SSS transmission.

26. The network device of any of claims 16 to 25, wherein the SSB does not include a physical broadcast channel (PBCH).

27. The network device of any of claims 16 to 25, wherein at least one frequency location of at least one PBCH in the SSB is further used for indicating the SSB index of the SSB.

28. The network device of claim 27, wherein the at least one frequency location of the at least one PBCH comprises a start subcarrier number of the at least one PBCH relative to a start of the SSB.

29. The network device of claim 28, wherein the start subcarrier number indicates the SSB index of the SSB based on a modulo operation for the following: the start subcarrier number; and a max number of SSBs.

30. The network device of any of claims 27 to 29, wherein at least one time location of the at least one PBCH in the SSB is further used for indicating the SSB index of the SSB.

31. A method comprising: receiving, from a network device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS); and determining an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

32. A method comprising: transmitting, to a terminal device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS), wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

33. An apparatus comprising: means for receiving, from a network device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS); and means for determining an SSB index of the SSB based on at least one frequency location of the at least one DMRS.

34. An apparatus comprising: means for transmitting, to a terminal device, a synchronization signal block (SSB) comprising at least one demodulation reference signal (DMRS), wherein at least one frequency location of the at least one DMRS is used for indicating an SSB index of the SSB.

35. A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method of claim 31 or 32.

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