Synchronization for dynamic spectrum sharing between cellular systems

Abstract

The present disclosure relates to an apparatus comprising: means for receiving (800) a synchronization signal block for a first cellular system from a network element; means for receiving (802) a synchronization signal block extension for the second cellular system from the network element or another network element based on the synchronization signal block for the first cellular system; and means for deriving (804) the content of the synchronization signal block for the second cellular system based at least on the synchronization signal block extension for the second cellular system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an apparatus, a method, and a computer program for transmitting and receiving a synchronization signal block for a first cellular system and a second cellular system.

[0002] For the purposes of the present disclosure, the phrases "at least one of A or B," "at least one of A and B," "A and / or B" mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrases "A or B" and "A and / or B" mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). BACKGROUND

[0003] A communication system can be seen as a facility that enables communication sessions between two or more entities such as communication devices, base stations, and / or other nodes by providing carriers for use as bearers of the data involved in the communication sessions.

[0004] The communication system can be a wireless communication system. Examples of wireless systems include public land mobile networks (PLMN) based on radio standards such as those provided by 3GPP, satellite based communication systems and different wireless local networks, e.g., wireless local area networks (WLAN). Wireless systems can typically be divided into cells, and are therefore often referred to as cellular systems.

[0005] Communication systems and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are allowed to do and / or required to do. The communication protocols and / or parameters to be used are also typically defined. An example of a standard is the so-called 5G standard. SUMMARY

[0006] According to one aspect, there is provided an apparatus comprising means for: receiving, from a network element, a synchronization signal block for a first cellular system; receiving, from the network element or another network element, a synchronization signal block extension for a second cellular system based on the synchronization signal block for the first cellular system; and deriving, based on at least the synchronization signal block extension for the second cellular system, content of a synchronization signal block for the second cellular system.

[0007] The apparatus can include means for receiving, from a network element, a synchronization signal block for a first cellular system, the synchronization signal block including a physical broadcast channel for the first cellular system; means for receiving, from the network element or another network element, a physical broadcast channel extension for a second cellular system based on the physical broadcast channel for the first cellular system; and means for deriving content of a physical broadcast channel for the second cellular system based at least on the physical broadcast channel extension for the second cellular system.

[0008] The first cellular system can include an NR cellular system, and the other second cellular system can include a 6G cellular system.

[0009] The content of the physical broadcast channel for the second cellular system can include a broadcast channel for the second cellular system.

[0010] The apparatus can include means for deriving the content of the physical broadcast channel for the second cellular system based only on the physical broadcast channel extension for the second cellular system.

[0011] The apparatus can include means for deriving the content of the physical broadcast channel for the second cellular system based on the physical broadcast channel for the first cellular system and the physical broadcast channel extension for the second cellular system.

[0012] Information included in the physical broadcast channel extension for the second cellular system can override some information included in the physical broadcast channel for the first cellular system.

[0013] The apparatus can include means for receiving, from the network element or another network element, a physical downlink shared channel for the second cellular system based on the physical broadcast channel extension for the second cellular system, the physical downlink shared channel for the second cellular system including a system information block for the second cellular system; and means for deriving the content of the physical broadcast channel for the second cellular system based on the physical broadcast channel for the first cellular system, the physical broadcast channel extension for the second cellular system, and the system information block for the second cellular system.

[0014] The apparatus can include means for receiving, from the network element or another network element, a physical downlink shared channel for the second cellular system based on the physical broadcast channel extension for the second cellular system, the physical downlink shared channel for the second cellular network system including a system information block for the second cellular system; and means for deriving the content of the physical broadcast channel for the second cellular system based on the physical broadcast channel extension for the second cellular system and the system information block for the second cellular system.

[0015] The physical broadcast channel extension for the second cellular system can include an indication of a physical downlink control channel configuration (e.g., control resource set). The apparatus can receive a physical downlink control channel for the second cellular system using the physical downlink control channel configuration. The physical downlink control channel for the second cellular system can schedule a physical downlink shared channel for the second cellular system. The physical downlink shared channel for the second cellular system can include a system information block for the second cellular system.

[0016] The apparatus can include means for receiving a physical downlink shared channel for the first cellular system from a network element or another network element, the physical downlink shared channel for the first cellular system including a system information block for the second cellular system; and means for deriving a content of a physical broadcast channel for the second cellular system based on the physical broadcast channel for the first cellular system, the physical broadcast channel extension for the second cellular system, and the system information block for the second cellular system.

[0017] The apparatus can include means for receiving a physical downlink shared channel for the first cellular system from a network element or another network element, the physical downlink shared channel for the first cellular system including a system information block for the second cellular system; and means for deriving a content of a physical broadcast channel for the second cellular system based on the physical broadcast channel extension for the second cellular system and the system information block for the second cellular system.

[0018] The apparatus can include means for detecting that a physical broadcast channel extension is available based on an indication included in a synchronization signal block for the first cellular system.

[0019] The apparatus can include means for detecting that a synchronization signal block for the first cellular system is received on a predetermined frequency location, wherein the predetermined frequency location indicates that a physical broadcast channel extension is available.

[0020] The apparatus can include means for detecting that a physical broadcast channel extension is available based on an indication included in a physical broadcast channel for the first cellular system.

[0021] The apparatus can include means for detecting that a master information block includes a reserved bit, the master information block being transmitted via a physical broadcast channel for the first cellular system, wherein the reserved bit indicates that a physical broadcast channel extension is available.

[0022] The apparatus can include means for detecting that a demodulation reference signal is received on resources allocated to a physical broadcast channel for the first cellular system and additional resources not allocated to the physical broadcast channel for the first cellular system, wherein the demodulation reference signal received on the additional resources indicates that a physical broadcast channel extension is available.

[0023] The apparatus can include means for blindly detecting that a physical broadcast channel extension for the second cellular system is available based on predetermined candidate locations of the physical broadcast channel extension for the second cellular system.

[0024] The synchronization signal block for the first cellular system and the synchronization signal block for the second cellular system have a same periodicity; or the synchronization signal block for the first cellular system and the synchronization signal block for the second cellular system have different periodicities.

[0025] The apparatus can include means for determining that the apparatus operates on one of a plurality of frequency bands, wherein both the first cellular system and the second cellular system operate on the plurality of frequency bands and dynamic spectrum sharing is applicable to the plurality of frequency bands.

[0026] The apparatus can include means for receiving a synchronization signal block for the first cellular system from a network element, the synchronization signal block for the first cellular system comprising at least one synchronization signal for the first cellular system and a physical broadcast channel for the first cellular system; and means for synchronizing to the network element based on the at least one synchronization signal for the first cellular system.

[0027] The at least one synchronization signal can be for the first cellular system and for the second cellular system. The first cellular system and the second cellular system can be synchronized.

[0028] According to one aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to receive a synchronization signal block for a first cellular system from a network element; receive a synchronization signal block extension for a second cellular system from the network element or another network element based on the synchronization signal block for the first cellular system; and derive content of a synchronization signal block for the second cellular system based at least on the synchronization signal block extension for the second cellular system.

[0029] According to one aspect, there is provided an apparatus comprising circuitry configured to receive a synchronization signal block for a first cellular system from a network element; receive a synchronization signal block extension for a second cellular system from the network element or another network element based on the synchronization signal block for the first cellular system; and derive content of a synchronization signal block for the second cellular system based at least on the synchronization signal block extension for the second cellular system.

[0030] According to an aspect, there is provided a method comprising: receiving, from a network element, a synchronization signal block for a first cellular system; receiving, from the network element or another network element, a synchronization signal block extension for a second cellular system based on the synchronization signal block for the first cellular system; and deriving, based on at least the synchronization signal block extension for the second cellular system, content of a synchronization signal block for the second cellular system.

[0031] According to an aspect, there is provided a computer program comprising computer executable code which, when run on at least one processor, is configured to: receive, from a network element, a synchronization signal block for a first cellular system; receive, from the network element or another network element, a synchronization signal block extension for a second cellular system based on the synchronization signal block for the first cellular system; and derive, based on at least the synchronization signal block extension for the second cellular system, content of a synchronization signal block for the second cellular system.

[0032] According to an aspect, there is provided an apparatus comprising means for: transmitting a synchronization signal block for a first cellular system; and transmitting a synchronization signal block extension for a second cellular system, from which content of a synchronization signal block for the second cellular system can be derived from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

[0033] The apparatus can comprise means for transmitting a synchronization signal block for a first cellular system, the synchronization signal block for the first cellular system comprising a physical broadcast channel for the first cellular system; and means for transmitting a physical broadcast channel extension for a second cellular system, from which content of a physical broadcast channel for the second cellular system can be derived from at least the physical broadcast channel extension for the second cellular system.

[0034] The synchronization signal block for the first cellular system comprises an indication indicating that a physical broadcast channel for the second cellular system is available.

[0035] The apparatus can comprise means for transmitting the synchronization signal block for the first cellular system on a predetermined frequency location, wherein the predetermined frequency location indicates that a physical broadcast channel extension for the second cellular system is available.

[0036] The physical broadcast channel for the first cellular system comprises an indication indicating that a physical broadcast channel extension for the second cellular system is available.

[0037] The apparatus can comprise means for transmitting, via the physical broadcast channel for the first cellular system, a master information block, the master information block comprising a reserved bit, wherein the reserved bit indicates that a physical broadcast channel extension is available.

[0038] The apparatus can comprise means for transmitting a demodulation reference signal on resources allocated to a physical broadcast channel for the first cellular system and additional resources not allocated to the physical broadcast channel for the first cellular system, wherein the demodulation reference signal transmitted on the additional resources indicates that a physical broadcast channel extension is available.

[0039] According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured to, with the at least one processor, cause the apparatus at least to transmit a synchronization signal block for a first cellular system; and transmit a synchronization signal block extension for a second cellular system, from which content of the synchronization signal block for the second cellular system can be derived from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

[0040] According to an aspect, there is provided an apparatus comprising circuitry configured to transmit a synchronization signal block for a first cellular system; and transmit a synchronization signal block extension for a second cellular system, from which content of the synchronization signal block for the second cellular system can be derived from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

[0041] According to an aspect, there is provided a method comprising transmitting a synchronization signal block for a first cellular system; and transmitting a synchronization signal block extension for a second cellular system, from which content of the synchronization signal block for the second cellular system can be derived from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

[0042] According to an aspect, there is provided a computer program comprising computer executable code which when run on at least one processor is configured to transmit a synchronization signal block for a first cellular system; and transmit a synchronization signal block extension for a second cellular system, from which content of the synchronization signal block for the second cellular system can be derived from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

[0043] According to an aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

[0044] According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

[0045] According to an aspect, there is provided a non-transitory tangible storage medium comprising program instructions stored thereon for performing at least one of the above-described methods.

[0046] In the foregoing, many different aspects have been described. It should be understood that any of the above-described aspects can be provided, implemented, and / or facilitated by a combination of any two or more of the above-described aspects.

[0047] Various other aspects are also described in the following detailed description and in the appended claims. List of Abbreviations AF: Application Function AMF: Access and Mobility Management Function API: Application Programming Interface BS: Base Station CU: Central Unit DL: Downlink DSS: Dynamic Shared Spectrum DU: Distributed Unit gNB: gNodeB GSM: Global System for Mobile Communications HSS: Home Subscriber Server IoT: Internet of Things LTE: Long Term Evolution MAC: Medium Access Control MIB: Master Information Block MRSS: Multi-Radio Spectrum Sharing MS: Mobile Station MTC: Machine Type Communication NEF: Network Exposure Function NF: Network Function NR: New Radio NRF: Network Repository Function PBCH: Physical Broadcast Channel PDCCH: Physical Downlink Control Channel PDSCH: Physical Downlink Shared Channel PDU: Packet Data Unit PSS: Primary Synchronization Signal RAM: Random Access Memory (R)AN: (Radio) Access Network RB: Resource Block ROM: Read-Only Memory SIB: System Information Block SIBCH: Synchronization Information and Initial System Information or Broadcast Channel SMF: Session Management Function SSB: Synchronization Signal / PBCH Block SSS: Secondary Synchronization Signal TR: Technical Report TS: Technical Specification UE: User Equipment UMTS: Universal Mobile Telecommunication System 3GPP: Third Generation Partnership Project 5G: Fifth Generation 5GC: 5G Core Network 6G: Sixth Generation BRIEF DESCRIPTION OF DRAWINGS

[0048] Embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

[0049] Figure 1 a schematic representation of a NR system is shown;

[0050] Figure 2 a schematic representation of a control device is shown;

[0051] Figure 3 a schematic representation of a user equipment is shown;

[0052] Figure 4 a structure of a NR synchronization signal block is shown;

[0053] Figure 5 a structure of a NR synchronization signal block frequency division multiplexed with a physical broadcast channel is shown;

[0054] Figure 6 a structure of a NR synchronization signal block time division multiplexed with a physical broadcast channel is shown;

[0055] Figure 7 a block diagram of a method performed by a 6G UE for receiving synchronization signal blocks for a NR system and a 6G system is shown;

[0056] Figure 8 a block diagram of a method performed by a device, such as a user equipment, for receiving synchronization signal blocks for a first cellular system and a second cellular system is shown;

[0057] Figure 9 a block diagram of a method performed by a device, such as a base station, for receiving synchronization signal blocks for a first cellular system and a second cellular system is shown; and

[0058] Figure 10 a schematic representation of a non-volatile memory medium storing instructions which, when executed by a processor, allow the processor to perform one or more of the steps of the method according to Figure 8 and Figure 9 . DETAILED DESCRIPTION

[0059] In the following, certain embodiments are explained with reference to mobile communication devices capable of communicating via a wireless cellular system and a mobile communication system serving such mobile communication devices. Before explaining the example embodiments in detail, it is to be understood that Figure 1 , Figure 2 and Figure 3 Certain general principles of wireless communication systems, their access systems, and mobile communication devices are briefly explained to help understand the technology underlying the described examples.

[0060] Figure 1 An illustrative representation of a NR system (i.e., a 5G system or a 5G-Advanced system) is shown. The NR system can comprise a user equipment (UE), a (radio) access network ((R)AN), a 5G core network (5GC), one or more application functions (AFs), and one or more data networks (DNs).

[0061] The 5G (R)AN can comprise one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) central unit functions. The gNB distributed unit functions can be part of a relay node (e.g., a distributed unit part of an integrated access and backhaul node).

[0062] The 5GC can comprise an access and mobility management function (AMF), a session management function (SMF), an authentication server function (AUSF), a user data management (UDM), a user plane function (UPF), and / or a network exposure function (NEF).

[0063] Figure 2 An example of a control apparatus 200 for controlling a function of a (R)AN or a 5GC as shown in Figure 1 The control apparatus can comprise at least one random access memory (RAM) 211a, at least one read-only memory (ROM) 211b, at least one processor 212, a processor 213, and an input / output interface 214. The at least one processor 212, the processor 213 can be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, the processor 213 can be configured to execute appropriate software code 215. For example, the software code 215 can allow to perform one or more steps to perform one or more aspects. The software code 215 can be stored in the ROM 211b. The control apparatus 200 can be interconnected with another control apparatus 200 controlling another function of the 5G (R)AN or the 5GC. In some embodiments, each function of the (R)AN or the 5GC comprises a control apparatus 200. In alternative embodiments, two or more functions of the (R)AN or the 5GC can share a control apparatus.

[0064] Figure 3The UE 300 (such as) is shown Figure 1 The example of the UE shown above. UE 300 can be provided by any device capable of transmitting and receiving radio signals. Non-limiting examples include mobile stations (MS) or mobile devices (such as mobile phones or so-called "smartphones"), computers provided with wireless interface cards or other wireless interface facilities (e.g., USB dongles), personal digital assistants (PDAs) or tablets provided with wireless communication capabilities, machine-type communication (MTC) devices, cellular Internet of Things (CIoT) devices, or any combination of these devices. UE 300 can be part of a relay node (e.g., a mobile terminal portion integrating access and backhaul nodes). For example, UE 300 can provide communication for carrying data. Communication can be one or more of voice, email, text messages, multimedia, data, machine data, etc.

[0065] UE 300 can receive signals via air or radio interface 307 through appropriate means for receiving, and can transmit signals via appropriate means for transmitting radio signals. Figure 3 In this diagram, the transceiver unit is schematically designated by block 306. For example, the transceiver unit 306 may be provided by a radio section and an associated antenna arrangement. This antenna arrangement may be located inside or outside the mobile device.

[0066] UE 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b, and other possible components 303 for assisting in the performance of tasks designed to be performed in software and hardware, including control of access to and communication with access systems and other communication devices. At least one processor 301 is coupled to RAM 302b and ROM 302a. At least one processor 301 may be configured to execute appropriate software code 308. Software code 308 may, for example, allow the execution of one or more of these aspects. Software code 308 may be stored in ROM 302a.

[0067] Processors, storage, and other related control devices may be provided on a suitable circuit board and / or chipset. This feature is indicated by reference numeral 304. The device may optionally have a user interface, such as a keypad 305, a touch-sensitive screen or board, or a combination thereof. Optionally, depending on the type of device, one or more of a display, speakers, and microphone may be provided.

[0068] One or more aspects of the present disclosure relate to dynamic spectrum sharing (DSS) between cellular systems, in particular between an NR system and a 6G system. DSS can include resource element DSS (i.e., frequency- and time-domain DSS, time-domain DSS only, or frequency-domain DSS only). DSS can sometimes be referred to as multi-radio spectrum sharing (MRSS). MRSS can be implemented in FR1 bands (i.e., sub-7 GHz) or FR2 bands (mmWave).

[0069] A 6G system will be the next generation cellular system to be standardized by 3GPP. 6G systems are currently being developed and aligned across the telecommunication industry in various research projects and forums. 3GPP studies on 6G system radio interface aspects are expected to start in time in 2025 or even 2024.

[0070] DSS between cellular systems means that the cellular systems share the same spectrum in a dynamic manner. As an example, DSS can be supported between an LTE system and an NR system. DSS between an NR system and a 6G system can also be important as it allows a gradual migration from 5G bands to 6G bands, and from 5G UEs to 6G UEs.

[0071] With DSS between an NR system and a 6G system, resources allocated to the NR system can be flexibly shared with the 6G system based on at least one of a number of 6G UEs and a 6G traffic volume. It can make that a 6G band dedicated to the 6G system has only a limited number (as opposed to a 6G band shared between the NR system and the 6G system), in particular at lower frequencies. Thus, DSS can facilitate a smooth introduction of the 6G system with sufficient coverage. Additionally, network vendors and operators can want to facilitate a smooth (software) upgrade of 5G hardware to 6G hardware.

[0072] DSS between a 5G system and a 6G system can require a tight frequency and time synchronization between the 5G system and the 6G system. DSS can also require coordination between schedulers to avoid unintended collisions on resource allocations. Thus, the 6G system can use a waveform and / or numerology that is compatible with the 5G system for efficient DSS (e.g., to avoid excessive guard bands and guard times between NR transmissions and 6G transmissions). For example, the waveform and / or numerology of the NR system can form a subset of the waveform and / or numerology of the 6G system. This can also be beneficial from an implementation perspective.

[0073] An NR channel raster defines a set of frequency locations on which an UL carrier or a DL carrier can be centered.

[0074] An NR synchronization signal / PBCH block (SSB) is a core building block of the NR system. The NR SSB is used for initial cell search and selection, beam and cell measurements, new beam identification in radio link monitoring and beam recovery procedures. The NR SSB can include an NR primary synchronization signal (PSS), an NR secondary synchronization signal (SSS), and an NR physical broadcast channel (PBCH). The NR PBCH can include a demodulation reference signal (DMRS) for NR PBCH demodulation.

[0075] Figure 4 The structure of the NR SSB is shown. The NR SSB can span twenty resource blocks (RBs) in the frequency domain and four orthogonal frequency-division multiplexing (OFDM) symbols in the time domain. The NR PSS can be communicated in a first OFDM symbol. The NR PBCH can be communicated in a second OFDM symbol. The NR PBCH and the NR SSS can be communicated in a third OFDM symbol. The NR PBCH can be communicated on a fourth OFDM symbol.

[0076] The NR synchronization raster defines a set of frequency locations on which the NR SSB can be located. The NR synchronization raster can set a set of frequency locations that need to be searched by the NR UE for initial cell search. To speed up cell search, the synchronization raster can be much sparser than the channel raster. For example, in the NR frequency range 1, the channel raster typically has a spacing of 100 kHz. The synchronization raster has a cluster of three frequency locations per 1.2 MHz, with offsets of 50 kHz, 150 kHz, and 250 kHz in each cluster.

[0077] The NR PBCH can include a master information block (MIB). The MIB can include at least one of the following: a system frame number, a subcarrier spacing for the cell, a frequency offset for the cell relative to the NR SSB, and an NR PDCCH configuration (e.g., for control resource set or CORESET #0). The NR PDCCH configuration can define a set of resources that the NR UE should monitor to obtain scheduling information for the NR PDSCH. The NR PDSCH can include a system information block 1 (SIB1). The MIB can include a reserved bit.

[0078] A technical problem of the DSS between the NR system and the 6G system can be that the NR system needs NR control signaling (e.g., the NR SSB, which includes the NR PSS, the NR SSS, and the NR PBCH), and the 6G system needs 6G control signaling (e.g., the 6G SSB, which includes the 6G PSS, the 6G SSS, and the 6G PBCH). The 6G control signaling incurs significant overhead.

[0079] In this disclosure, a 6G SSB can include any 6G control signaling or initial control signaling. A 6G SSB can include synchronization information and initial system information or broadcast channel (SIB CH).

[0080] In beam-based NR systems and beam-based 6G systems, the overhead can be even more significant, where NR control signaling (e.g., NR SSB, which includes NR PSS, NR SSS, and NR PBCH) and 6G control signaling (e.g., 6G SSB, which includes 6G PSS, 6G SSS, and 6G PBCH) are transmitted to different beams sequentially (at least to some extent).

[0081] One or more aspects of the disclosure provide a mechanism to allow DSS between NR systems and 6G systems while minimizing the overhead caused by 6G control signaling.

[0082] One or more aspects of the disclosure provide a mechanism to allow DSS between NR systems and 6G systems while providing NR SSBs to NR UEs and 6G SSBs to 6G UEs in an efficient manner (e.g., reduced overhead).

[0083] One or more aspects of the disclosure provide a mechanism to allow DSS between NR systems and 6G systems while synchronizing NR UEs with NR systems and 6G UEs with 6G systems in an efficient manner (e.g., reduced overhead).

[0084] One or more aspects of the disclosure provide a mechanism to allow DSS between NR systems and 6G systems while providing system information for NR systems to NR UEs and system information for 6G systems to 6G UEs in an efficient manner (e.g., reduced overhead).

[0085] Efficient DSS between NR systems and 6G systems can require time and frequency synchronization between NR systems and 6G systems. Therefore, using NR timing and frequency can not provide a significant limitation.

[0086] 6G PBCH extensions can provide additional information to 6G UEs (e.g., additional 6G synchronization signals if synchronization implemented with NR SSBs is not suitable or sufficient for 6G systems).

[0087] 6G PBCH extensions can not need to follow the 5G NR air interface design beyond timing, frequency positioning, and having sufficient orthogonality to 5G NR signals (e.g., by using OFDM with the same subcarrier spacing or by using a guard band).

[0088] One or more aspects of the present disclosure provide a mechanism in which NR SSB and 6G SSB are provided in a hierarchical structure. A portion of 6G SSB (e.g., 6G PSS and 6G SSS) can be a portion of NR SSB and can be derived from NR SSB. A portion of 6G SSB (e.g., 6G PBCH) can not be a portion of NR SSB and can be derived from an extension (e.g., 6G PBCH extension) separate from NR SSB.

[0089] Alternatively, all of 6G SSB (e.g., 6G PSS, 6G SSS, and 6G PBCH) can not be a portion of NR SSB and can be derived from an extension (e.g., 6G PSS extension, 6G SSS extension, and 6G PBCH extension) separate from NR SSB.

[0090] One or more aspects of the present disclosure provide a mechanism in which NR SSB and 6G SIBCH are provided in a hierarchical structure. A portion of 6G SIBCH (e.g., 6G synchronization information) can be a portion of NR SSB. A portion of 6G SIBCH (e.g., 6G initial system information or broadcast channel) can not be a portion of NR SSB and can be derived from an extension (e.g., 6G initial system information or broadcast channel extension) separate from NR SSB.

[0091] NR SSB and 6G SSB can have the same periodicity. That is, there can be a one-to-one mapping between NR SSB and 6G SSB. Alternatively, NR SSB and 6G SSB can have different periodicities. That is, there can be an N-to-1 mapping between NR SSB and 6G SSB. For example, there can be a two-to-one mapping between NR SSB and 6G SSB (i.e., one 6G SSB is transmitted every other NR SSB).

[0092] A 6G UE can have prior knowledge of a predetermined frequency band on which both an NR system and a 6G system can operate and on which a DSS can be applied. When the 6G UE determines that the 6G UE operates on a frequency band in the predetermined frequency band, the 6G UE can receive a 6G SSB, as described below.

[0093] Initially, a 6G UE can receive an NR SSB from a BS. The 6G UE can be served by the BS or by another BS. The NR SSB can include an NR PSS, an NR SSS, and an NR PBCH. The NR system and the 6G can be synchronized, and thus the NR PSS and the NR SSS can also serve as a 6G PSS and a 6G SSS (or 6G synchronization signals or to provide 6G synchronization information). Thus, based on the NR PSS and the NR SSS, the 6G UE can synchronize to the BS.

[0094] Based on the NR SSB, the 6G UE can detect that a 6G PBCH extension is available for the 6G UE. The NR SSB can include an indication that the 6G PBCH extension is available for the 6G UE. The indication that the 6G PBCH extension is available for the 6G UE can be explicit or implicit.

[0095] The explicit indication can be conveyed in a reserved bit of an NR MIB transmitted via the NR PBCH. The NR UE can ignore the reserved bit.

[0096] The implicit indication that the 6G PBCH extension is available for the 6G UE can be conveyed by transmitting a DMRS on resources allocated to the NR PBCH and on additional resources not allocated to the NR PBCH. That is, the DMRS is transmitted on more than twenty physical resource blocks, unlike in the legacy NR system. If the 6G UE detects that the DMRS is transmitted on resources allocated to the NR PBCH and on additional resources not allocated to the NR PBCH, the 6G UE can detect the indication that the 6G PBCH extension is available for the 6G UE.

[0097] Another implicit indication that the 6G PBCH extension is available for the 6G UE can be conveyed by transmitting the NR SSB on a frequency location (i.e., a grid point) among a plurality of predetermined frequency locations (i.e., grid points). The predetermined frequency locations can be a subset of frequency locations allowed to transmit the NR SSB. If the 6G UE detects that the frequency location (i.e., a grid point) on which the NR SSB is transmitted is among the predetermined frequency locations, the 6G UE can detect the indication that the PBCH extension is available for the 6G UE.

[0098] Based on the NR SSB, the 6G UE can determine the location of PBCH extension (i.e., timing, frequency, and / or quasi-co-location). The 6G UE can use time and / or frequency synchronization determined based on the NR SSB. The 6G UE can apply predetermined time and / or frequency offsets to the time and / or frequency location of the NR SSB detection thereon to determine the time and / or frequency resources for 6GPBCH extension. In other words, the 6G PBCH extension time and / or frequency location may be relative to the NR SSB time and / or frequency location. Furthermore, the 6G UE can also use the same beam, spatial domain filter, or spatial receiver parameters (see 3GPP TS 38.214) determined for PBCH extension reception.

[0099] like Figure 5 As shown, the 6G PBCH extension can be frequency-division multiplexed with the NR SSB. The 6G PBCH extension can reside on a resource block adjacent to the NR SSB resource block.

[0100] Additional or alternative land, such as Figure 6 As shown, the 6G PBCH extension can be time-division multiplexed with the NR SSB. Some locations within the NR SSB can carry the 6G PBCH extension instead of the NR PBCH.

[0101] It should be understood that the NR SSB does not necessarily need to include an indication that the 6G PBCH extension is available for the 6G UE. Based on the predetermined candidate positioning for the 6G PBCH extension, the 6G UE can blindly detect that the 6G PBCH extension is available for the 6G UE. The predetermined candidate positioning can be relative to the NR SSB.

[0102] A 6G UE can receive a 6G PBCH extension from a BS. Based on the 6G PBCH extension or NR PBCH, a 6G UE can receive a 6GSIB (e.g., 6G SIB1). The 6G PBCH extension or NR PBCH can include information for receiving the 6G SIB from the BS. This information can include a 6G PDCCH configuration (e.g., 6G CORESET#0). The 6G PDCCH can schedule a 6G PDSCH (or a 6G physical downlink data channel) that includes the 6G SIB. Alternatively, the NR PDCCH can schedule an NR PDSCH that includes the 6G SIB. The NRPDCCH can be transmitted on NR CORESET#0, where the NR PDCCH is identified using a 6G-specific RNTI. This identification can be based on masking the PDCCH cyclic redundancy check using the 6G-specific RNTI. The 6G-specific RNTI can be predetermined (e.g., in the standard) or indicated on the 6G PBCH extension.

[0103] The 6G PBCH extension can include an indication to indicate whether the 6G UE can obtain the content of the 6G PBCH, i.e., 6G broadcast channel (BCH) (i.e., logical channel), based on only the 6G PBCH extension, or based on the 6G PBCH extension and the NR PBCH, or based on the 6G PBCH extension, the NR PBCH and the 6G SIB, as described below.

[0104] The 6G UE can obtain the 6G BCH based on at least the 6G PBCH extension. The 6G BCH, similar to the NR BCH, can include system information.

[0105] In an example, the 6G UE can obtain the 6G BCH based on only the 6G PBCH extension (i.e., not based on the NR PBCH). The information included in the 6G BCH includes the information included in the 6G PBCH extension and does not include the information included in the NR PBCH.

[0106] In another example, the 6G UE can obtain the 6G BCH based on the 6G PBCH extension and the NR PBCH. The information included in the 6G BCH includes the information included in the 6G PBCH extension and the information included in the NR PBCH. The information included in the 6G PBCH extension can override some of the information included in the NR PBCH. For example, the “PDCCH configuration for SIB1 (8 bits)” can be overridden by the 6G BCH, while the system frame number (SFN) for 6G can be obtained based on the NR PBCH.

[0107] In another example, the 6G UE can obtain the 6G BCH based on the 6G PBCH extension, the NR PBCH and the 6G SIB. The information included in the 6G BCH includes the information included in the 6G PBCH extension, the information included in the NR PBCH and the information included in the 6G SIB.

[0108] The information included in the NR PBCH can include at least one of: SSB index, system frame number, half frame bit, reserved bits (2 or 0 bits), symbol time and frequency synchronization, cell barring.

[0109] The information included in the 6G PBCH extension can include at least one of: subcarrier spacing, SSB subcarrier offset, downlink control channel configuration, PDCCH configuration SIB1, offset to 6G downlink channel, or downlink waveform.

[0110] The information contained in the 6G BCH can include at least one of: SSB index from NR PBCH, system frame number, half frame bit, reserved bits (2 or 0 bits), symbol time and frequency synchronization, cell barring, and from 6G PBCH extension at least one of: subcarrier spacing, SSB subcarrier offset, downlink control channel configuration, PDCCH configuration SIB1, offset to 6G downlink channel, or downlink waveform.

[0111] The 6G PBCH can be transmitted in a manner that prevents NR UEs from decoding the 6G PBCH. The 6G PBCH can use different encoding, scrambling, and / or mapping to resources than the NR PBCH.

[0112] Figure 7 A block diagram illustrating an overview of a method performed by a 6G UE for receiving NR SSB and 6G SSB is shown.

[0113] In step 700, the 6G UE can receive, from a 6G BS, an NR SSB including an NR PSS, an NR SSS, and an NR PBCH.

[0114] In step 702, based on the NR PSS and the NR SSS, the 6G UE can synchronize to the BS.

[0115] In step 704, the 6G UE can detect that a 6G PBCH extension is available.

[0116] In step 706, the 6G UE can receive, from the BS, the 6G PBCH extension.

[0117] In step 708, the 6G UE can receive, from the BS, a 6G SIB.

[0118] In step 710, based on the 6G PBCH extension and possibly the NR PBCH and / or the 6G SIB, the 6G UE can derive the 6G PBCH.

[0119] Figure 8 A block diagram illustrating a method performed by an apparatus, such as a UE, for receiving SSBs for a first cellular system and for a second cellular system is shown.

[0120] In step 800, the apparatus can receive, from a network element, an SSB for a first cellular system. In step 802, based on the SSB for the first cellular system, the apparatus can receive, from the network element or another network element, an SSB extension for a second cellular system. In step 804, based at least on the SSB extension for the second cellular system, the apparatus can derive, from the network element, content of an SSB for the second cellular system.

[0121] The apparatus can receive, from the network unit, an SSB for the first cellular system, the SSB including a PBCH for the first cellular system. The apparatus can receive, from the network unit or another network unit, a PBCH extension for a second cellular system based on the SSB for the first cellular system. The apparatus can derive, from the network unit, content of the PBCH for the second cellular system based at least on the PBCH extension for the second cellular system.

[0122] The first cellular system can include an NR cellular system, and the other second cellular system can include a 6G cellular system.

[0123] The content of the PBCH for the second cellular system can include a BCH for the second cellular system.

[0124] The apparatus can derive the content of the PBCH for the second cellular system based only on the PBCH extension for the second cellular system.

[0125] The apparatus can derive the content of the PBCH for the second cellular system based on the PBCH for the first cellular system and the PBCH extension for the second cellular system.

[0126] Information included in the PBCH extension for the second cellular system can override some information included in the PBCH for the first cellular system.

[0127] The apparatus can receive, from the network unit or another network unit, a PDSCH for the second cellular system based on the PBCH extension for the second cellular system, the PDSCH for the second cellular system including a SIB for the second cellular system. The apparatus can derive the content of the PBCH for the second cellular system based on the PBCH for the first cellular system, the PBCH extension for the second cellular system, and the SIB for the second cellular system.

[0128] The apparatus can receive, from the network unit or another network unit, a PDSCH for the second cellular system based on the PBCH extension for the second cellular system, the PDSCH for the second cellular system including a SIB for the second cellular system. The apparatus can derive the content of the PBCH for the second cellular system based on the PBCH extension for the second cellular system and the SIB for the second cellular system.

[0129] The PBCH extension for the second cellular system can include an indication of a PDCCH configuration (e.g., a control resource set). The apparatus can receive a PDCCH for the second cellular system using the PDCCH configuration. The PDCCH for the second cellular system can schedule a PDSCH for the second cellular system. The PDSCH for the second cellular system can include a SIB for the second cellular system.

[0130] The apparatus can receive, from the network unit or another network unit, a PDSCH for the first cellular system, the PDSCH for the first cellular system including a SIB block for the second cellular system. The apparatus can derive content of a PBCH for the second cellular system based on the PBCH for the first cellular system, the PBCH extension for the second cellular system, and the SIB for the second cellular system.

[0131] The apparatus can receive, from the network unit or another network unit, a PDSCH for the first cellular system, the PDSCH for the first cellular system including a SIB block for the second cellular system. The apparatus can derive content of a PBCH for the second cellular system based on the PBCH extension for the second cellular system and the SIB for the second cellular system.

[0132] The apparatus can detect, based on an indication included in a SSB for the first cellular system, that a PBCH extension for the second cellular system is available.

[0133] The apparatus can detect that a SSB for the first cellular system is received on a predetermined frequency location, wherein the predetermined frequency location indicates that a PBCH extension is available.

[0134] The apparatus can detect, based on an indication included in a PBCH for the first cellular system, that a PBCH extension is available.

[0135] The apparatus can detect that a MIB includes a reserved bit, the MIB being transmitted via a PBCH for the first cellular system, wherein the reserved bit indicates that a PBCH extension is available.

[0136] The apparatus can detect that a DMRS is received on resources allocated to a PBCH for the first cellular system and additional resources not allocated to the PBCH for the first cellular system, wherein the DMRS received on the additional resources indicates that a PBCH extension is available.

[0137] The apparatus can blindly detect, based on a predetermined candidate location of a PBCH extension for the second cellular system, that the PBCH extension for the second cellular system is available.

[0138] A SSB for the first cellular system and a SSB for the second cellular system can have a same periodicity, or a SSB for the first cellular system and a SSB for the second cellular system can have different periodicities.

[0139] The apparatus can determine that the apparatus operates on a frequency band of a plurality of frequency bands, wherein both the first cellular system and the second cellular system operate on the plurality of frequency bands and wherein the DSS applies to the plurality of frequency bands.

[0140] The apparatus can receive, from a network unit, an SSB for a first cellular system, the SSB for the first cellular system including at least one synchronization signal for the first cellular system and a PBCH for the first cellular system. The apparatus can synchronize to the network unit based on the at least one synchronization signal for the first cellular system.

[0141] The at least one synchronization can be for the first cellular system and for a second cellular system. The first cellular system and the second cellular system can be synchronized.

[0142] Figure 9 A block diagram of a method performed by an apparatus, such as a BS, for receiving an SSB for a first cellular system and for a second cellular system is shown.

[0143] In step 900, the apparatus can transmit an SSB for a first cellular system. In step 902, the apparatus can transmit an SSB extension for a second cellular system from which content for the SSB for the second cellular system can be derived.

[0144] The apparatus can transmit an SSB for a first cellular system, the SSB for the first cellular system including a PBCH for the first cellular system. The apparatus can transmit a PBCH extension for a second cellular system from which content for the PBCH for the second cellular system can be derived.

[0145] The SSB for the first cellular system can include an indication indicating that a PBCH extension for a second cellular system is available.

[0146] The apparatus can transmit the SSB for the first cellular system on a predetermined frequency location, where the predetermined frequency location indicates that a PBCH extension for a second cellular system is available.

[0147] The PBCH for the first cellular system can include an indication indicating that a PBCH extension for a second cellular system is available.

[0148] The apparatus can transmit, via the PBCH for the first cellular system, a MIB including a reserved bit, where the reserved bit indicates that the PBCH extension is available.

[0149] The apparatus can transmit a DMRS on resources allocated to the PBCH for the first cellular system and additional resources not allocated to the PBCH for the first cellular system, where the DMRS transmitted on the additional resources indicates that the PBCH extension is available.

[0150] Figure 10A schematic representation of a non-volatile memory medium 1000 storing instructions and / or parameters which, when executed by a processor, allow the processor to perform Figure 8 and Figure 9 one or more of the steps of the method of

[0151] It is noted that while the above describes example embodiments, several changes and modifications to the disclosed solutions can be made without departing from the scope of the present application.

[0152] It should be appreciated that although the above concepts have been discussed in the context of NR and 6G systems, one or more of these concepts can be applied to other cellular systems.

[0153] Accordingly, embodiments can vary in scope within the scope of the appended claims. In general, some embodiments can be implemented in hardware or special-purpose circuits, software, logic or any combination thereof. For example, some aspects can be implemented in hardware, while other aspects can be implemented in

[0154] Embodiments can be realized by computer software stored in memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard, it should be noted that any procedures, e.g., as shown in Figure 8 and Figure 9 illustrated, can represent program steps, or interconnected logic circuits, blocks and functions, or combinations of program steps and logic circuits, blocks and functions. The software can be stored on such physical media as memory chips, or memory blocks implemented in the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and CD ROMs.

[0155] The memory can be of any type appropriate for the local technical environment and can be implemented using any appropriate data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processor can be of any type appropriate for the local technical environment, and can encompass one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), gate level circuits and processors based on multi core processor architectures, as non-limiting examples.

[0156] Alternatively or additionally, some embodiments can be implemented using circuitry. The circuitry can be configured to perform one or more of the previously described functions and / or method steps. The circuitry can be provided in a base station and / or a communication device.

[0157] As used in this application, the term "circuitry" can refer to one or more or all of the following: (a) hardware-only circuitry such as amongst others an analogue and / or digital circuitry; (b) combinations of hardware circuits and software such as: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any parts of hardware processor with software (including digital signal processor); and (c) hardware circuit(s) themselves, requiring software (e.g. firmware) for operation, e.g., a part of a microprocessor(s) or a part of a microprocessor(s) such as a digital signal processor, but software not being present when it is not required for operation.

[0158] This definition of circuitry applies to all uses of this term in this application including any claims. As a further example, as used in this application, the term circuitry also covers an implementation that has a sole hardware circuit or processor (or multiple processors) or a sole hardware circuit or processor plus software and / or firmware that work together to make up the circuitry does not require software to operate, but software can be needed when it is not required for operation.

[0159] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiments complete enough to enable a person of ordinary skill in the art to make or use the teachings without additional contributions from the patent literature. However, numerous modifications, adaptations, and changes will readily occur to those skilled in the art, some of which have been described in the description above. All such modifications, adaptations, and changes are intended to fall within the scope of the appended claims, which are to be interpreted in accordance with the principles of patent law including 35 U.S.C. § 101.

Claims

1. An apparatus comprising: means for receiving, from a network element, a synchronization signal block for a first cellular system; means for receiving, from the network element or another network element, a synchronization signal block extension for a second cellular system based on the synchronization signal block for the first cellular system; and means for deriving content of a synchronization signal block for the second cellular system based at least on the synchronization signal block extension for the second cellular system.

2. The apparatus of claim 1, comprising: means for receiving, from the network element, the synchronization signal block for the first cellular system, the synchronization signal block for the first cellular system comprising a physical broadcast channel for the first cellular system; means for receiving, from the network element or another network element, a physical broadcast channel extension for the second cellular system based on the physical broadcast channel for the first cellular system; and means for deriving content of a physical broadcast channel for the second cellular system based at least on the physical broadcast channel extension for the second cellular system.

3. The apparatus of claim 2, comprising: means for deriving the content of the physical broadcast channel for the second cellular system based only on the physical broadcast channel extension for the second cellular system.

4. The apparatus of claim 2, comprising: means for deriving the content of the physical broadcast channel for the second cellular system based on the physical broadcast channel for the first cellular system and the physical broadcast channel extension for the second cellular system.

5. The apparatus of claim 2, comprising: means for receiving, from the network element or another network element, a physical downlink shared channel for the second cellular system based on the physical broadcast channel extension for the second cellular system, the physical downlink shared channel for the second cellular system comprising a system information block for the second cellular system; and means for deriving content of the physical broadcast channel for the second cellular system based on the physical broadcast channel for the first cellular system, the physical broadcast channel extension for the second cellular system, and the system information block for the second cellular system.

6. The apparatus of claim 2, comprising: means for receiving, from the network element or another network element, a physical downlink shared channel for the second cellular system based on the physical broadcast channel extension for the second cellular system, the physical downlink shared channel for the second cellular network system comprising a system information block for the second cellular system; and means for deriving content of the physical broadcast channel for the second cellular system based on the physical broadcast channel extension for the second cellular system and the system information block for the second cellular system.

7. The apparatus of claim 2, comprising: means for receiving, from the network element or another network element, a physical downlink shared channel for the first cellular system, the physical downlink shared channel for the first cellular system comprising a system information block for the second cellular system; and means for deriving, based on the physical broadcast channel for the first cellular system, the physical broadcast channel extension for the second cellular system, and the system information block for the second cellular system, content of the physical broadcast channel for the second cellular system.

8. The apparatus of claim 2, comprising: means for receiving, from the network element or another network element, a physical downlink shared channel for the first cellular system, the physical downlink shared channel for the first cellular system comprising a system information block for the second cellular system; and means for deriving, based on the physical broadcast channel extension for the second cellular system and the system information block for the second cellular system, content of the physical broadcast channel for the second cellular system.

9. The apparatus of any one of claims 1 to 7, comprising: means for detecting, based on an indication comprised in the synchronization signal block for the first cellular system, that the physical broadcast channel extension for the second cellular system is available.

10. The apparatus of claim 9, comprising: means for detecting that the synchronization signal block for the first cellular system is received on a predetermined frequency location, wherein the predetermined frequency location indicates that the physical broadcast channel extension is available.

11. The apparatus of claim 9, comprising: means for detecting, based on an indication comprised in the physical broadcast channel for the first cellular system, that the physical broadcast channel extension is available.

12. The apparatus of claim 11, comprising: means for detecting that a master information block comprises a reserved bit, the master information block being transmitted via the physical broadcast channel for the first cellular system, wherein the reserved bit indicates that the physical broadcast channel extension is available.

13. The apparatus of claim 11, comprising: means for detecting that a demodulation reference signal is received on resources allocated to the physical broadcast channel for the first cellular system and additional resources not allocated to the physical broadcast channel for the first cellular system, wherein the demodulation reference signal received on additional resources indicates that the physical broadcast channel extension is available.

14. The apparatus of any one of claims 1 to 5, comprising: means for blindly detecting, based on a predetermined candidate positioning of the physical broadcast channel extension for the second cellular system, that the physical broadcast channel extension for the second cellular system is available.

15. The apparatus of any one of claims 1 to 14, wherein the synchronization signal block for the first cellular system and the synchronization signal block for the second cellular system have a same periodicity; or wherein the synchronization signal block for the first cellular system and the synchronization signal block for the second cellular system have different periodicities.

16. The apparatus of any of claims 1 to 15, comprising: means for determining that the apparatus operates on a frequency band of a plurality of frequency bands, wherein both the first cellular system and the second cellular system operate on the plurality of frequency bands and dynamic spectrum sharing is applicable to the plurality of frequency bands.

17. The apparatus of any of claims 1 to 16, comprising: means for receiving, from the network unit, the synchronization signal block for the first cellular system, the synchronization signal block for the first cellular system comprising at least one synchronization signal for the first cellular system and the physical broadcast channel for the first cellular system; and means for synchronizing to the network unit based on the at least one synchronization signal for the first cellular system.

18. An apparatus, comprising: means for transmitting a synchronization signal block for a first cellular system; and means for transmitting a synchronization signal block extension for the second cellular system, such that content for a synchronization signal block for a second cellular system is obtainable from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

19. The apparatus of claim 16, comprising: means for transmitting the synchronization signal block for the first cellular system, the synchronization signal block for the first cellular system comprising a physical broadcast channel for the first cellular system; and means for transmitting a physical broadcast channel extension for the second cellular system, such that content for a physical broadcast channel for the second cellular system is obtainable at least from the physical broadcast channel extension for the second cellular system.

20. The apparatus of claim 19, wherein the synchronization signal block for the first cellular system comprises an indication indicating that the physical broadcast channel for the second cellular system is available.

21. The apparatus of claim 20, comprising: means for transmitting the synchronization signal block for the first cellular system on a predetermined frequency location, wherein the predetermined frequency location indicates that the physical broadcast channel extension for the second cellular system is available.

22. The apparatus of claim 20, wherein the physical broadcast channel for the first cellular system comprises an indication indicating that the physical broadcast channel extension for the second cellular system is available.

23. The apparatus of claim 22, comprising: means for transmitting, via the physical broadcast channel for the first cellular system, a master information block, the master information block comprising a reserved bit, wherein the reserved bit indicates that the physical broadcast channel extension is available.

24. The apparatus of claim 22, comprising: a component for transmitting a demodulation reference signal on resources allocated to the physical broadcast channel for the first cellular system and additional resources not allocated to the physical broadcast channel for the first cellular system, wherein the demodulation reference signal transmitted on the additional resources indicates that the physical broadcast channel extension is available.

25. A method comprising: receiving, from a network element, a synchronization signal block for a first cellular system; receiving, from the network element or another network element, a synchronization signal block extension for a second cellular system based on the synchronization signal block for the first cellular system; and obtaining, based at least on the synchronization signal block extension for the second cellular system, content of a synchronization signal block for the second cellular system.

26. A method comprising: transmitting a synchronization signal block for a first cellular system; and transmitting a synchronization signal block extension for the second cellular system such that content of a synchronization signal block for a second cellular system can be obtained from the synchronization signal block for the first cellular system and the synchronization signal block extension for the second cellular system.

27. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method according to claim 25 or claim 26.

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