Enabling use of multiple transmission and reception points during initial access in wireless networks

Abstract

Devices, methods and computer programs for enabling use of multiple transmission and reception points during initial access in wireless networks are disclosed. At least some example embodiments may allow enabling TRP level granularity for synchronization signal block (SSB) transmissions in a cell comprising one or multiple TRPs.

Description

[0001] ENABLING USE OF MULTIPLE TRANSMISSION AND RECEPTION

[0002] POINTS DURING INITIAL ACCESS IN WIRELESS NETWORKS

[0003] TECHNICAL FIELD

[0004] The disclosure relates generally to communications and, more particularly but not exclusively, to enabling use of multiple transmission and reception points during initial access in wireless networks, as well as related devices, methods and computer programs.

[0005] BACKGROUND

[0006] Synchronization signals and channels such as a physical broadcast channel (PBCH) are utilized in mobile telecommunications (e.g., fifth generation (5G) and sixth generation (6G) wireless networks) to facilitate a user equipment (UE) to perform an initial access procedure (including, e.g., an initial system and cell search, as well as time and frequency synchronizations) .

[0007] E.g., 5G wireless networks support beamforming for the synchronization signals and PBCH by defining multiple time domain locations in a periodic manner for synchronization signal and PBCH blocks (SSBs) .

[0008] However, 5G wireless networks were originally designed with a single transmission and reception point (TRP) scenario in mind for the initial access. Although later releases of 5G wireless networks have been updated with support for multiple TRPs, it is still only for connected mode UEs.

[0009] Also, currently SSBs are defined and transmitted at cell level, i.e., SSBs represent beams of a cell rather than beams of TRPs of the cell. Yet, since there can be multiple TRPs in a cell and each TRP may have a certain spatial aperture or sector to cover with the SSBs (or in general with blocks providing UE with syn- chroni zation signals and PBCH) , at least in some s ituations it may be beneficial at least from an ef ficiency point of view for UEs to get into a TRP level granularity already in an initial access phase .

[0010] BRIEF SUMMARY

[0011] The scope of protection sought for various example embodiments of the invention is set out by the independent claims . The example embodiments and features , i f any, described in this speci fication that do not fall under the scope o f the independent claims are to be interpreted as examples useful for understanding various example embodiments of the invention .

[0012] An example embodiment of a user device comprises at least one processor, and at least one memory storing instructions that , when executed by the at least one processor, cause the user device at least to initiate an initial acces s procedure in a radio access network cell comprising one or more transmission and reception points , TRPs . The instructions , when executed by the at least one processor, further cause the user device at least to obtain synchroni zation signal information . The instructions , when executed by the at least one processor, further cause the user device at least to determine at least one of a cell identi fier of the radio access network cell or one or more TRP indices of the one or more TRPs based on the obtained synchronization signal information . The instructions , when executed by the at least one processor, further cause the user device at least to proceed with the initial access procedure for the one or more TRPs based on at least one of the determined cell identi fier or the determined one or more TRP indices . The synchroni zation signal information comprises one or more TRP speci fic synchroni zation signal blocks , SSBs . The obtaining of the synchroni zation signal information comprises detecting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs .

[0013] In an example embodiment, alternatively or in addition to the above-described example embodiments, the one or more TRP specific SSBs are received in temporally subsequent synchronization signal bursts, each burst including an SSB specific to one TRP of the one or more TRPs .

[0014] In an example embodiment, alternatively or in addition to the above-described example embodiments, each burst is comprised in a half-frame.

[0015] In an example embodiment, alternatively or in addition to the above-described example embodiments, the one or more TRP specific SSBs are received such that each TRP specific SSB includes a same primary synchronization signal, PSS, in each frequency division multiplexing, FDM, related location.

[0016] In an example embodiment, alternatively or in addition to the above-described example embodiments, each TRP specific SSB is located on a same synchronization raster.

[0017] In an example embodiment, alternatively or in addition to the above-described example embodiments, the instructions, when executed by the at least one processor, further cause the user device to determine whether the radio access network cell comprises more than one TRP.

[0018] In an example embodiment, alternatively or in addition to the above-described example embodiments, the instructions, when executed by the at least one processor, further cause the user device to determine at least one of a number of TRPs comprised in the radio access network cell or a maximum number of TRPs for the radio access network cell.

[0019] In an example embodiment, alternatively or in addition to the above-described example embodiments, the instructions , when executed by the at least one processor, further cause the user device to determine one or more spatial parameters for other TRP speci fic SSBs in the radio access network cell .

[0020] In an example embodiment , alternatively or in addition to the above-described example embodiments , the instructions , when executed by the at least one processor, further cause the user device to determine at least one of a frequency resource or a time resource for other TRP speci fic SSBs in the radio access network cell .

[0021] An example embodiment of a method comprises initiating, by a user device , an initial acces s procedure in a radio access network cel l comprising one or more transmission and reception points , TRPs . The method further comprises obtaining, by the user device , synchroni zation signal information . The method further comprises determining, by the user device , at least one of a cell identi fier of the radio access network cell or one or more TRP indices of the one or more TRPs based on the obtained synchroni zation signal information . The method further comprises proceeding, by the user device , with the initial access procedure for the one or more TRPs based on at least one of the determined cell identi fier or the determined one or more TRP indices . The synchroni zation signal information comprises one or more TRP speci fic synchroni zation signal blocks , SSBs . The obtaining of the synchroni zation signal information comprises detecting the one or more TRP specific SSBs from the speci fic TRP of the one or more TRPs .

[0022] An example embodiment of an apparatus comprises means for carrying out a method according to any of the above-described example embodiments .

[0023] An example embodiment of a computer program comprises instructions for causing a user device to perform at least the following : initiating an initial access procedure in a radio access network cell comprising one or more transmission and reception points , TRPs ; obtaining synchroni zation signal information; determining at least one of a cell identi fier of the radio access network cell or one or more TRP indices of the one or more TRPs based on the obtained synchroni zation signal information; and proceeding with the initial access procedure for the one or more TRPs based on at least one of the determined cell identi fier or the determined one or more TRP indices . The synchroni zation signal information comprises one or more TRP speci fic synchroni zation signal blocks , SSBs . The obtaining of the synchroni zation signal information comprises detecting the one or more TRP speci fic SSBs from the speci fic TRP of the one or more TRPs .

[0024] An example embodiment of a network node 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 node device at least to transmit, to a user device , synchroni zation signal information . The synchroni zation signal information comprises at least one of a cell identi fier of a radio access network cell or one or more transmission and reception point , TRP, indices of one or more TRPs in the radio access network cell . The instructions , when executed by the at least one processor, further cause the network node device at least to receive , from the user device , a signal for the one or more TRPs based on at least one o f the cel l identi f ier or the one or more TRP indices . The synchroni zation signal information comprises one or more TRP specific synchroni zation signal blocks , SSBs . The transmitting the synchroni zation signal information comprises transmitting the one or more TRP speci fic SSBs from the specific TRP of the one or more TRPs .

[0025] An example embodiment of a method comprises transmitting, from a network node device to a user device , synchroni zation signal information . The synchroni zation signal information comprises at least one of a cell identi fier of a radio access network cell or one or more transmission and reception point , TRP, indices of one or more TRPs in the radio access network cell . The method further comprises receiving, at the network node device from the user device , a signal for the one or more TRPs based on at least one of the cell identi fier or the one or more TRP indices . The synchroni zation signal information comprises one or more TRP speci fic synchroni zation signal blocks , SSBs . The transmitting the synchroni zation signal information comprises transmitting the one or more TRP speci fic SSBs from the speci fic TRP of the one or more TRPs .

[0026] An example embodiment of an apparatus comprises means for carrying out a method according to any of the above-described example embodiments .

[0027] An example embodiment of a computer program comprises instructions for causing a network node device to perform at least the following : transmitting to a user device synchroni zation signal information comprising at least one of a cell identi fier of a radio access network cel l or one or more transmis sion and reception point , TRP, indices of one or more TRPs in the radio access network cell ; and receiving from the user device a signal for the one or more TRPs based on at least one of the cel l identi f ier or the one or more TRP indices . The synchronization signal information comprises one or more TRP speci fic synchroni zation signal blocks , SSBs . The transmitting the synchroni zation signal information comprises transmitting the one or more TRP speci fic SSBs from the speci fic TRP of the one or more TRPs .

[0028] DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings , which are included to provide a further understanding of the embodiments and constitute a part of this specification, illustrate embodiments and together with the description help to explain the principles of the embodiments . In the drawings :

[0030] FIG . 1 shows an example embodiment of the subj ect matter described herein illustrating an example system, where various embodiments of the present disclosure may be implemented;

[0031] FIG . 2A shows an example embodiment of the subj ect matter described herein illustrating a user device ;

[0032] FIG . 2B shows an example embodiment of the subj ect matter described herein illustrating a network node device ;

[0033] FIG . 3A shows an example embodiment of the subj ect matter described herein illustrating a method for a user device ;

[0034] FIG . 3B shows an example embodiment of the subj ect matter described herein illustrating a method for a network node device ;

[0035] FIG . 4 shows an example embodiment of the subj ect matter described herein illustrating a disclosed SSB ;

[0036] FIG . 5 shows an example embodiment of the subj ect matter described herein illustrating transmission of SSBs of di f ferent TRPs in a spatial multiplexing manner ; and

[0037] FIG . 6 shows an example embodiment of the subj ect matter described herein illustrating transmission of a TRP index as non-scrambled .

[0038] Like reference numerals are used to designate like parts in the accompanying drawings .

[0039] DETAILED DESCRIPTION

[0040] Reference will now be made in detail to embodiments , examples of which are illustrated in the accompanying drawings . The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0041] Fig. 1 illustrates example system 100, where various embodiments of the present disclosure may be implemented. System 100 may comprise radio access network cell 110 of a fifth generation (5G) new radio (NR) network or of a network beyond 5G wireless networks. An example representation of system 100 is shown depicting user device 200, network node device 220, and transmission and reception points (TRPs) 210A, 210B. At least in some embodiments, the network of radio access network cell 110 may be comprised in a massive machine-to-ma- chine (M2M) network, massive machine type communications (mMTC) network, internet of things (loT) network, industrial internet-of-things (IIoT) network, enhanced mobile broadband (eMBB) network, ultra-reliable low-latency communication (URLLC) network, and / or the like. In other words, the network of radio access network cell 110 may be configured to serve diverse service types and / or use cases, and it may logically be seen as comprising one or more networks.

[0042] User device 200 may include, e.g., a mobile phone, a smartphone, a tablet computer, a smart watch, or any hand-held, portable and / or wearable device. User device 200 may also be referred to as a user equipment (UE) . Network node device 220 may comprise, e.g., a base station. The base station may include, e.g., any device suitable for providing an air interface for user devices to connect to a wireless network via wireless transmissions .

[0043] At least in some embodiments, TRPs 210A, 210B may comprise a set of geographically co-located antennas (e.g., an antenna array with one or more antenna elements) supporting a transmit processing functionality and / or a receive processing functionality. An example scenario is a multiple room apartment with a transmitter in each room. When user device 200 moves within a cell, it may transit between beams on the same TRP and between beams on different TRPs to maintain connection. The TRP may be transparent to user device 200 since user device 200 may see mobility only between beams. In outdoor scenarios, radio access network cell 110 may also comprise multiple TRPs, e.g., TRPs located on lamp posts.

[0044] In the following, various example embodiments will be discussed. At least some of these example embodiments described herein may allow enabling use of multiple transmission and reception points during initial access in wireless networks.

[0045] Furthermore, at least some of the example embodiments described herein may allow enabling TRP level granularity for synchronization signal block (SSB) transmissions in a cell comprising one or multiple TRPs.

[0046] Furthermore, at least some of the example embodiments described herein may allow establishing multi- TRP connections already in the initial access phase, thereby making it possible to reduce needed configuration signalling (from UE specific to cell specific) and the related latency.

[0047] Furthermore, at least some of the example embodiments described herein may allow enabling a time and frequency offset tracking at a TRP level already in the initial access phase, thereby facilitating leveraging of different multi-TRP operations.

[0048] Furthermore, at least some of the example embodiments described herein may allow enabling a user device to identify SSBs already at the TRP level, and / or to identify reference signal (s) associated with the SSB already at the TRP level. Furthermore , at least some of the example embodiments described herein may allow enabling the use of multiple transmission and reception points during the initial access in the wireless networks in a way that makes it possible to use a narrow bandwidth in order to reduce searcher complexity and power consumption .

[0049] Fig . 2A is a block diagram of user device 200 , in accordance with an example embodiment .

[0050] User device 200 comprises one or more processors 202 and one or more memories 204 that comprise computer program code . User device 200 may also include other elements , such as transceiver 206 configured to enable user device 200 to transmit and / or receive information to / from other devices , as well as other elements not shown in Fig . 2A. In one example , user device 200 may use transceiver 206 to transmit or receive signalling information and data in accordance with at least one cellular communication protocol . Transceiver 206 may be configured to provide at least one wireless radio connection, such as for example a 3GPP mobile broadband connection ( e . g . , 5G or 6G) . Transceiver 206 may comprise , or be conf igured to be coupled to , at least one antenna to transmit and / or receive radio frequency signals .

[0051] Although user device 200 is depicted to include only one processor 202 , user device 200 may include more processors . In an embodiment , memory 204 i s capable of storing instructions , such as an operating system and / or various applications . Furthermore , memory 204 may include a storage that may be used to store , e . g . , at least some of the information and data used in the disclosed embodiments .

[0052] Furthermore , processor 202 is capable of executing the stored instructions . In an embodiment , processor 202 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, processor 202 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP) , a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , a microcontroller unit (MCU) , a hardware accelerator, a special-purpose computer chip, a neural network (NN) chip, an artificial intelligence (Al) accelerator, a tensor processing unit (TPU) , a neural processing unit (NPU) , or the like. In an embodiment, processor 202 may be configured to execute hard-coded functionality. In an embodiment, processor 202 is embodied as an executor of software instructions, wherein the instructions may specifically configure processor 202 to perform the algorithms and / or operations described herein when the instructions are executed.

[0053] Memory 204 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, memory 204 may be embodied as semiconductor memories (such as mask ROM, PROM (programmable ROM) , EPROM (erasable PROM) , flash ROM, RAM (random access memory) , etc . ) .

[0054] User device 200 may comprise any of various types of devices used directly by an end user entity and capable of communication in a wireless network, such as a user equipment (UE) . Such devices include but are not limited to smartphones, tablet computers, smart watches, lap top computers, internet-of-things (loT) devices, massive machine-to-machine (M2M) devices, massive machine type communications (mMTC) devices, industrial internet-of-things (IIoT) devices, enhanced mobile broadband (eMBB) devices, ultra-reliable low-latency communication (URLLC) devices, relay nodes (such as integrated access and backhaul nodes) configured to facilitate backhaul connections, and / or devices mounted in vehicles, etc.

[0055] When executed by at least one processor 202, instructions stored in at least one memory 204 cause user device 200 at least to initiate an initial access procedure in radio access network cell 110 comprising one or more transmission and reception points (TRPs) 210A, 210B. For example, user device 200 may search primary synchronization signals (PSSs) according to a predetermined synchronization raster in given band(s) , and upon PSS detection, user device 200 may detect a secondary synchronization signal (SSS) according to a fixed resource (time-frequency) relation between the PSS and SSS, as discussed below in more detail.

[0056] The instructions, when executed by at least one processor 202, further cause user device 200 at least to obtain synchronization signal information.

[0057] The instructions, when executed by at least one processor 202, further cause user device 200 at least to determine a cell identifier of radio access network cell 110 and / or one or more TRP indices of one or more TRPs 210A, 210B based on the obtained synchronization signal information.

[0058] The instructions, when executed by at least one processor 202, further cause user device 200 at least to proceed with the initial access procedure for one or more TRPs 210A, 210B based on the determined cell identifier and / or the determined one or more TRP indices.

[0059] The synchronization signal information comprises one or more TRP specific synchronization signal blocks (SSBs) . The obtaining of the synchronization signal information comprises detecting the one or more TRP specific SSBs from the specific TRP of one or more TRPs 210A, 210B. In other words, TRP specific SSBs may be transmitted across the TRPs, e.g., in a TDM manner or an FDM manner .

[0060] At least in some embodiments, the one or more TRP specific SSBs may be received in temporally subsequent synchronization signal bursts, each burst including an SSB specific to one TRP of one or more TRPs 210A, 210B. For example, each burst may be comprised in a half-frame .

[0061] In other words, TRP specific SSBs may be transferred in a TDM manner so that one TRP may transmit SSBs in one SSB burst (e.g., within a half frame) , the next TRP may transmit SSBs in the next SSB burst (e.g., in the next occurring half frame) , and so on. There may be, e.g., up to four TRPs transmitting within an 80 millisecond (ms) period so that each TRP transmits with an 80 ms periodicity.

[0062] At least in some embodiments, the one or more TRP specific SSBs may be received such that each TRP specific SSB includes a same primary synchronization signal (PSS) in each frequency division multiplexing (FDM) related location. For example, each TRP specific SSB may be located on a same synchronization raster.

[0063] In other words, TRP specific SSBs may be transferred in an FDM manner. In this scenario, each TRP- specific SSB may also comprise a separate PSS which may be configured to be the same PSS in each FDM location. Each TRP specific SSB may be located on the same synchronization raster, thereby allowing the initial user device 200 search to be made agnostic to TRP.

[0064] At least in some embodiments, the instructions, when executed by at least one processor 202, may further cause user device 200 to determine whether radio access network cell 110 comprises more than one TRP.

[0065] At least in some embodiments, the instructions, when executed by at least one processor 202, may further cause user device 200 to determine a number of TRPs 210A, 210B comprised in radio access network cell 110 and / or a maximum number of TRPs 210A, 21 OB for radio access network cell 110.

[0066] At least in some embodiments, the instructions, when executed by at least one processor 202, may further cause user device 200 to determine one or more spatial parameters for other TRP specific SSBs in radio access network cell 110.

[0067] At least in some embodiments, the instructions, when executed by at least one processor 202, may further cause user device 200 to determine a frequency resource and / or a time resource for other TRP specific SSBs in radio access network cell 110.

[0068] At least in some embodiments, the synchronization signal information may comprise an SSB. The obtaining of the synchronization signal information may comprise detecting a TRP specific SSS and / or a PBCH DMRS . An SSS sequence initialization and / or a PBCH DMRS sequence initialization may be based on the determined cell identifier and / or the determined one or more TRP indices .

[0069] At least in some embodiments, the TRP specific SSS may comprise the cell identifier and the TRP index of each TRP.

[0070] In other words, the SSS signal may be TRP specific and have both the cell identifier and the TRP index as components in sequence initialization. The PBCH DMRS may also have the cell identifier and the TRP index as components in sequence initialization, e.g., in addition to three least significant bits (LSBs) of slot timing information (i.e., three LSBs of an SSB index) .

[0071] At least in some embodiments, the SSB may further include a primary synchronization signal (PSS) common to each TRP of one or more TRPs 210A, 210B.

[0072] In other words, the PSS signal may be common to all the TRPs, and optionally may be transmitted simultaneously by multiple TRPs. At least in some embodiments, at least the cell identifier and the one or more TRP indices may be included in the PBCH scrambling code initialization. Furthermore, the instructions, when executed by at least one processor 202, may further cause user device 200 to combine PBCHs transmitted from different TRPs after descrambling the PBCHs with the PBCH scrambling code including the cell identifier and the one or more TRP indices .

[0073] In other words, the PBCH scrambling code initialization may have at least either the cell identifier or both the cell identifier and TRP index / indices as components .

[0074] When the PBCH scrambling code initialization has at least the cell identifier as a component, the PBCH may be transmitted, e.g., in a system frame number (SFN) manner from multiple TRPs. Each TRP may have a TRP specific DMRS based on which user device 200 may determine TRP specific doppler and time domain channel estimate parameters for channel estimation filters to receive an SFN based PBCH.

[0075] When the PBCH scrambling code initialization has at least the cell identifier and TRP index / indices as components, user device 200 may combine the PBCHs after descrambling the PBCHs with the cell identifier and TRP index / indices -based scrambling code. Also, this may be advantageous when user device 200 is soft-combining PBCHs of a same TRP since it also allows randomizing interference among the TRPs.

[0076] At least in some embodiments, the one or more TRP indices may be included in the PBCH DMRS sequence when defining the length of a sequence from which a part is selected to be transmitted according to the SSB index, or according to a timing index and a TRP index of the SSB.

[0077] For example, an SSB index may index SS block time locations from 0 to L-l in an increasing order within a half radio frame. For the case of L = 8 or L = 64, three LSBs of an SS block time index may be indicated by eight different PBCH-DMRS sequences {a_0,..., a_7 } . For the case of L = 4, two LSBs of an SS block time index may be indicated by four different PBCH-DMRS sequences {b_0,..., b_3 } . One remaining bit out of three LSBs may be set to 0 and not transmitted by the PBCH, or indicate, e.g., whether an SS block is transmitted in the first or second 5 millisecond (ms) half-frame of a radio frame .

[0078] In other words, the PBCH DMRS sequence may also have the TRP index as a component when initializing the PBCH DMRS sequence, and / or when defining the length of the (long) sequence from which a certain part is selected to be transmitted according to the SSB index, or according to the timing index and the TRP index of the SSB. It is to be noted that the DMRS having both at least the SSB index and the TRP index as components resulting in having up to eight TRP indices embedded in the DMRS resulting in 64 different DMRS sequences does not impact on performance significantly compared to, e.g., 32 different sequences when the RS density is kept in three or four within an PRB .

[0079] At least in some embodiments, the SSB may include a separate reference signal indicating a TRP index. For example, the separate reference signal may be used as the PBCH DMRS or as an additional PBCH DMRS.

[0080] In other words, a separate reference signal within an SSB may be transmitted that indicates the TRP index. It may also be used as a PBCH DMRS or as an additional PBCH DMRS. For instance, the additional reference signal (RS) may be frequency domain multiplexed with an SSS, and PBCH symbols may be transmitted without an embedded DMRS. For example, an SSS and a TRP index RS may be used as a PBCH DMRS. At least in some embodiments, a synchronization signal included in the synchronization signal information may be based on a constant amplitude zero autocorrelation (CAZAC) sequence in which different root sequences represent cell identifiers.

[0081] In other words, a synchronization signal, e.g., an SSS or a PBCH DMRS signal may be based on a CAZAC sequence where different root sequences represent physical cell identifiers.

[0082] At least in some embodiments, an orthogonal cover code (OCC) , a Walsh sequence, or a discrete Fourier transform (DFT) sequence may be included for resource elements of the PBCH DMRS.

[0083] In other words, e.g., an orthogonal cover code (OCC) or a Walsh sequence (e.g., with a length K) may be defined for resource elements of a PBCH DMRS to enable TRP separation, where K>1, e.g., 2 or 4 or 8. This may be applied in addition to the TRP and cell specific initialization of the PBCH DMRS, on top of a cell-specific comb-offset hopping to enable interference randomization among a potential set of TRPs under a certain cell identifier. Furthermore, the cell-specific DMRS comb-offset hopping may be defined for a group of TRPs based comb-offset hopping, where each group may include at least one TRP which is associated with a specific frequency offset associated with the PBCH DMRS combtype .

[0084] At least in some embodiments, the maximum number of TRPs may be specific to a frequency layer, and this may be signalled to user device 200 once it is in a connected mode. At least in some embodiments, this may reduce the number of hypotheses user device 200 may use in decoding the TRP information.

[0085] To summarize, the disclosure allows enabling TRP level granularity for the SSB transmissions in a cell comprising one or multiple TRPs. This principle is illustrated in diagram 500 of Fig. 5 in which SSBs of different TRPs are transmitted in a spatial multiplexing manner. In other words, diagram 500 represents an SSB 501 supporting a multi-TRP scenario. In the example of diagram 500, there are 16 SSB indices (from 0 to 15) 503 with a unique time position. On top of them, there are TRP indices 502. Diagram 500 covers an example scenario with three TRPs. The parallel SSBs (for the three TRPs) may be transmitted on same frequency / time resources since they are spatially separated with unique DMRS sequences. In another scenario, multiple parallel SSBs may be transmitted on different frequency resources, e.g., frequency division multiplexed with each other.

[0086] As discussed above, at least in some embodiment, the SSB detection may be made agnostic to the TRP dimension. That is, when receiving an SSB (and / or, e.g., an associated system information block #1 (SIB1) ) correctly, user device 200 is able to determine at least one of the following:

[0087] - multi-TRP usage in cell 110 (yes / no) ;

[0088] - the number of TRPs used in cell 110 (or a maximum number, e.g., from a set of maximum numbers 1, 2, 4) . User device 200 may use this information, e.g., for detecting or using it for a hypothesis for the measurement of one or more other SSBs in cell 110;

[0089] - spatial parameters for (other) TRP -specific SSBs in cell 110;

[0090] - frequency / time resources for (other) TRP - specific SSBs in cell 110.

[0091] At least in some embodiments, the TRP index RS may be defined so that the sequence initialization has at least one of the following:

[0092] - a cell identifier (SSS) ;

[0093] - an SSB index; or

[0094] - a TRP index.

[0095] Diagram 400 of Fig. 4 illustrates a disclosed SSB including PSS 401, PBCHs 402, RSs 403, and SSS 404. As can be seen from diagram 400, at least in some embodiments, the TRP index RS sequence or sequence initialization may comprise information providing user device 200 the number or maximum number of TRPs used in cell 110. The resulting sequence may thus identify the TRP ID and the number of TRPs. Thus, user device 200 may determine the TRP ID and the number of TRPs based on one detection .

[0096] At least in some embodiments, any RS sequence or sequence initialization that is used to identify TRPs may comprise information providing user device 200 the number or maximum number of TRPs used in cell 110. The resulting sequence may thus identify the TRP ID and the number of TRPs. Thus, user device 200 may determine the TRP ID and the number of TRPs based on one detection.

[0097] At least in some embodiments, different sets of sequences identifying TRPs may be used for different number of TRPs in cell 110:

[0098] - one set of sequences for one TRP in cell 110;

[0099] - one set of sequences for two TRPs in cell 110; and

[0100] - one set of sequences for four TRPs in cell 110.

[0101] As discussed above, at least in some embodiments, the SSS may have both the cell identifier and the TRP index as components. Yet, having up to four TRP indices embedded in the SSS resulting in 2016 different sequences does not impact detection performance.

[0102] At least in some embodiments, the obtaining of the synchronization signal information comprising the SSB may comprise detecting a PBCH DMR. The one or more TRP indices may be included in one or more first PBCH scrambling codes. The obtaining of the synchronization signal information may further comprise detecting a secondary synchronization signal (SSS) . In other words, the TRP index may be added as a component to the first scrambling code, e.g., to enable more robust soft-combining of the PBCHs of the same TRP (when combining before the descrambling) and across the TRPs (when combining after the descrambling) .

[0103] For example, the first scrambling code of a two-stage scrambling of PBCH encoding may be based on, e.g., the cell identifier, and second and third LSBs of an SFN. A second scrambling code of the two-stage scrambling of the PBCH encoding may be based on, e.g., the cell identifier, and second and / or third LSBs of an SSB index .

[0104] At least in some embodiments, the one or more first PBCH scrambling code bits comprise one or more physical layer bits of the PBCH not scrambled with a second level scrambling code. For example, the one or more physical layer bits may further comprise system frame number (SFN) bits.

[0105] In other words, a number of SFN bits may be added into such physical layer bits of the PBCH that are not scrambled with a second level scrambling code.

[0106] At least in some embodiments, the instructions, when executed by at least one processor 202, may further cause user device 200 to determine time domain information based on the SFN bits. For example, the time domain information may comprise a slot index.

[0107] Diagram 600 of Fig. 6 illustrates transmission of a TRP index as non-scrambled, showing SS block 610 having 10-bit SFN 601, 3-bit TRP index 602, 1-bit HF 603, 6-bit SS block position index 604, and symbol timing 605. Diagram 600 further shows PBCH scrambled part (1st scrambling) 620, PBCH non-scrambled part 630, and PBCH DMRS 640. In other words, user device 200 may determine time domain information (e.g., a slot index) from DMRS 640 (e.g., three LSBs when the number of SSBs is not more than eight, and three most significant bits (MSBs) when the number of SSBs is between eight and 64) from the physical layer bits. The timing information may be sent, e.g., in an SFN manner from the simultaneous TRPs while TRP index 602 may be transmitted in a nonscrambled (i.e., the first scrambling code) manner. That is, TRP index 602 may not be scrambled by the first scrambling code in this embodiment, as illustrated by dashed line 650.

[0108] Fig. 3A illustrates an example flow chart of method 300 for user device 200, in accordance with an example embodiment.

[0109] At operation 301, user device 200 initiates the initial access procedure in radio access network cell 110 comprising one or more TRPs 210A, 210B.

[0110] At operation 302, user device 200 obtains the synchronization signal information.

[0111] At optional operation 303, user device 200 may determine whether radio access network cell 110 comprises more than one TRP.

[0112] At optional operation 304, user device 200 may determine the number of TRPs 210A, 210B comprised in radio access network cell 110 and / or the maximum number of TRPs 210A, 210B for radio access network cell 110.

[0113] At optional operation 305, user device 200 may determine the one or more spatial parameters for the other TRP specific SSBs in radio access network cell 110.

[0114] At optional operation 306, user device 200 may determine the frequency resource and / or the time resource for the other TRP specific SSBs in radio access network cell 110.

[0115] At operation 307, user device 200 determines the cell identifier of radio access network cell 110 or the one or more TRP indices of one or more TRPs 210A, 210B based on the obtained synchronization signal information .

[0116] At operation 308, user device 200 proceeds with the initial access procedure for one or more TRPs 210A, 210B based on the determined cell identi fier and / or the determined one or more TRP indices . As discus sed above in more detail , synchroni zation signal information comprises one or more TRP speci fic SSBs . The obtaining 302 of the synchronization signal information comprises detecting the one or more TRP specific SSBs from the speci fic TRP of one or more TRPs 210A, 210B .

[0117] Embodiments and examples with regard to Fig . 3A may be carried out by user device 200 of Fig . 2A. Operations 301-308 may, for example , be carried out by at least one processor 202 and at least one memory 204 . Further features of method 300 directly resulting from the functionalities and parameters of user device 200 are not repeated here . Method 300 can be carried out by computer program ( s ) or portions thereof .

[0118] Another example of an apparatus suitable for carrying out the embodiments and examples with regard to Fig . 3A comprises means for : initiating, at operation 301 , the initial access procedure in radio access network cell 110 comprising one or more TRPs 210A, 210B ; obtaining, at operation 302 , the synchroni zation signal information; determining, at operation 307 , the cell identi fier of radio access network cell 110 or the one or more TRP indices of one or more TRPs 210A, 210B based on the obtained synchroni zation signal information; and proceeding, at operation 308 , with the initial access procedure for each of one or more TRPs 210A, 210B based on at least one of the determined cell identi fier or the determined one or more TRP indices , wherein : the synchroni zation signal information comprises the one or more TRP speci fic SSBs ; and the obtaining, at operation 302 , of the synchroni zation signal information comprises detecting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs 210A, 210B.

[0119] Fig. 2B is a block diagram of network node device 220, in accordance with an example embodiment.

[0120] Network node device 220 comprises one or more processors 222 and one or more memories 224 that comprise computer program code. Network node device 220 may also include other elements, such as transceiver 226 configured to enable network node device 220 to transmit and / or receive information to / from other devices, as well as other elements not shown in Fig. 2B. In one example, network node device 220 may use transceiver 226 to transmit or receive signalling information and data in accordance with at least one cellular communication protocol. Transceiver 226 may be configured to provide at least one wireless radio connection, such as for example a 3GPP mobile broadband connection (e.g., 5G advanced or beyond) . Transceiver 226 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals.

[0121] Although network node device 220 is depicted to include only one processor 222, network node device 220 may include more processors. In an embodiment, memory 224 is capable of storing instructions, such as an operating system and / or various applications. Furthermore, memory 224 may include a storage that may be used to store, e.g., at least some of the information and data used in the disclosed embodiments.

[0122] Furthermore, processor 222 is capable of executing the stored instructions. In an embodiment, processor 222 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, processor 222 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP) , a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , a microcontroller unit (MCU) , a hardware accelerator, a special-purpose computer chip, a neural network (NN) chip, an artificial intelligence (Al) accelerator, a tensor processing unit (TPU) , a neural processing unit (NPU) , or the like. In an embodiment, processor 222 may be configured to execute hard-coded functionality. In an embodiment, processor 222 is embodied as an executor of software instructions, wherein the instructions may specifically configure processor 222 to perform the algorithms and / or operations described herein when the instructions are executed.

[0123] Memory 224 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, memory 224 may be embodied as semiconductor memories (such as mask ROM, PROM (programmable ROM) , EPROM (erasable PROM) , flash ROM, RAM (random access memory) , etc . ) .

[0124] Network node device 220 may comprise a base station, and / or a relay node (such as an integrated access and backhaul node) configured to facilitate child (access) links for client devices connected to the relay node. The base station may include, e.g., a 5G advanced or 6G base station (gNB) or any such device providing an air interface for user device 200 to connect to a wireless network via wireless transmissions, e.g., through TRPs 210A, 21 OB.

[0125] When executed by at least one processor 222, instructions stored in at least one memory 224 cause network node device 220 at least to transmit to user device 200 the synchronization signal information comprising the cell identifier of radio access network cell 110 or one or more TRP indices of one or more TRPs 210A, 210B in radio access network cell 110.

[0126] The instructions, when executed by at least one processor 222, further cause network node device 220 at least to receive from user device 200 a signal for one or more TRPs 210A, 210B based on the cell identifier and / or the one or more TRP indices.

[0127] The synchronization signal information comprises one or more TRP specific SSBs, and the transmitting (311) the synchronization signal information comprises transmitting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs 210A, 210B.

[0128] Further features of network node 220 directly result from the functionalities and parameters of user device 200 and thus are not repeated here.

[0129] Fig. 3B illustrates an example flow chart of method 310 for network node device 220, in accordance with an example embodiment.

[0130] At operation 311, network node device 220 transmits to user device 200 the synchronization signal information comprising the cell identifier of radio access network cell 110 and / or the one or more TRP indices of one or more TRPs 210A, 210B in radio access network cell 110.

[0131] At operation 312, network node device 220 receives from user device 200 the signal for one or more TRPs 210A, 210B based on the cell identifier and / or the one or more TRP indices. As discussed above, the synchronization signal information comprises one or more TRP specific SSBs, and the transmitting (at operation 311) the synchronization signal information comprises transmitting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs 210A, 210B.

[0132] Embodiments and examples with regard to Fig. 3B may be carried out by user device 200 of Fig. 2B. Operations 311-312 may, for example, be carried out by at least one processor 222 and at least one memory 224 . Further features of method 310 directly resulting from the functionalities and parameters of network node device 220 are not repeated here . Method 310 can be carried out by computer program ( s ) or portions thereof .

[0133] Another example of an apparatus suitable for carrying out the embodiments and examples with regard to Fig . 3B comprises means for : transmitting, at operation 311 , to user device 200 the synchroni zation signal information comprising the cell identi fier of radio access network cell 110 and / or the one or more TRP indices of one or more TRPs 210A, 210B in radio access network cell 110 . receiving, at operation 312 , from user device 200 the signal for one or more TRPs 210A, 210B based on the cell identifier and / or the one or more TRP indices , such that the synchroni zation signal information comprises one or more TRP speci fic SSBs , and the transmitting, at operation 311 , the synchroni zation signal information comprises transmitting the one or more TRP speci fic SSBs from the speci f ic TRP of the one or more TRPs 210A, 210B .

[0134] The functionality described herein can be performed, at least in part , by one or more computer program product components such as software components . According to an embodiment , user device 200 and / or network node device 220 may comprise a processor or processor circuitry, such as for example a microcontroller, configured by the program code when executed to execute the embodiments of the operations and functionality described . Alternatively, or in addition, the functionality described herein can be performed, at least in part , by one or more hardware logic components . For example , and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays ( FPGAs ) , Application-speci fic In- tegrated Circuits (ASICs) , Application-specific Standard Products (ASSPs) , System-on-a-chip systems (SOCs) , Complex Programmable Logic Devices (CPLDs) , Tensor Processing Units (TPUs) , and Graphics Processing Units (GPUs) .

[0135] Any range or device value given herein may be extended or altered without losing the effect sought. Also, any embodiment may be combined with another embodiment unless explicitly disallowed.

[0136] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter 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 examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

[0137] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items.

[0138] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought.

[0139] The term 'comprising' is used herein to mean including the method, blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements .

[0140] It will be understood that the above descrip- tion is given by way of example only and that various modi f ications may be made by those s kil led in the art . The above speci fication, examples and data provide a complete description of the structure and use of exemplary embodiments . Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments , those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this speci fica- tion .

Claims

CLAIMS :

1. A user device (200) , comprising: at least one processor (202) ; and at least one memory (204) storing instructions that, when executed by the at least one processor (202) , cause the user device (200) at least to: initiate an initial access procedure in a radio access network cell (110) comprising one or more transmission and reception points, TRPs (210A, 210B) ; obtain synchronization signal information; determine at least one of a cell identifier of the radio access network cell (110) or one or more TRP indices of the one or more TRPs (210A, 210B) based on the obtained synchronization signal information; and proceed with the initial access procedure for the one or more TRPs (210A, 210B) based on at least one of the determined cell identifier or the determined one or more TRP indices, wherein : the synchronization signal information comprises one or more TRP specific synchronization signal blocks, SSBs; and the obtaining of the synchronization signal information comprises detecting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs (210A, 210B) .

2. The user device (200) according to claim 1, wherein the one or more TRP specific SSBs are received in temporally subsequent synchronization signal bursts, each burst including an SSB specific to one TRP of the one or more TRPs (210A, 210B) .

3. The user device (200) according to claim 2, wherein each burst is comprised in a half-frame.

4. The user device (200) according to claim 1, wherein the one or more TRP specific SSBs are received such that each TRP specific SSB includes a same primary synchronization signal, PSS, in each frequency division multiplexing, FDM, related location.

5. The user device (200) according to claim 4, wherein each TRP specific SSB is located on a same synchronization raster.

6. The user device (200) according to any of claims 1 to 5, wherein the instructions, when executed by the at least one processor (202) , further cause the user device (200) to determine whether the radio access network cell (110) comprises more than one TRP .

7. The user device (200) according to any of claims 1 to 6, wherein the instructions, when executed by the at least one processor (202) , further cause the user device (200) to determine at least one of a number of TRPs (210A, 210B) comprised in the radio access network cell (110) or a maximum number of TRPs (210A, 210B) for the radio access network cell (110) .

8. The user device (200) according to any of claims 1 to 7, wherein the instructions, when executed by the at least one processor (202) , further cause the user device (200) to determine one or more spatial parameters for other TRP specific SSBs in the radio access network cell (110) .

9. The user device (200) according to any of claims 1 to 8, wherein the instructions, when executed by the at least one processor (202) , further cause the user device (200) to determine at least one of a frequency resource or a time resource for other TRP specific SSBs in the radio access network cell (110) .

10. A method (300) , comprising: initiating (301) , by a user device (200) , an initial access procedure in a radio access network cell (110) comprising one or more transmission and reception points, TRPs (210A, 210B) ; obtaining (302) , by the user device (200) , synchronization signal information; determining (307) , by the user device (200) , at least one of a cell identifier of the radio access network cell (110) or one or more TRP indices of the one or more TRPs (210A, 210B) based on the obtained synchronization signal information; and proceeding (308) , by the user device (200) , with the initial access procedure for the one or more TRPs (210A, 210B) based on at least one of the determined cell identifier or the determined one or more TRP indices, wherein : the synchronization signal information comprises one or more TRP specific synchronization signal blocks, SSBs; and the obtaining (302) of the synchronization signal information comprises detecting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs (210A, 210B) .

11. An apparatus, comprising means for carrying out the method (300) according to claim 10.

12. A computer program comprising instructions for causing a user device to perform at least the following : initiating an initial access procedure in a radio access network cell comprising one or more transmission and reception points, TRPs; obtaining synchronization signal information;determining at least one of a cell identifier of the radio access network cell or one or more TRP indices of the one or more TRPs based on the obtained synchronization signal information; and proceeding with the initial access procedure for the one or more TRPs based on at least one of the determined cell identifier or the determined one or more TRP indices, wherein : the synchronization signal information comprises one or more TRP specific synchronization signal blocks, SSBs; and the obtaining of the synchronization signal information comprising the one or more TRP specific SSBs comprises detecting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs.

13. A network node device (220) , comprising: at least one processor (222) ; and at least one memory (224) storing instructions that, when executed by the at least one processor (222) , cause the network node device (220) at least to: transmit, to a user device (200) , synchronization signal information, wherein the synchronization signal information comprises at least one of a cell identifier of a radio access network cell (110) or one or more transmission and reception point, TRP, indices of one or more TRPs (210A, 210B) in the radio access network cell (110) ; and receive, from the user device (200) , a signal for the one or more TRPs (210A, 210B) based on at least one of the cell identifier or the one or more TRP indices, wherein : the synchronization signal information comprises one or more TRP specific synchronization signal blocks, SSBs; andthe transmitting the synchronization signal information comprises transmitting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs (210A, 210B) .

14. A method (310) , comprising: transmitting (311) , from a network node device (220) to a user device (200) , synchronization signal information, wherein the synchronization signal information comprises at least one of a cell identifier of a radio access network cell (110) or one or more transmission and reception point, TRP, indices of one or more TRPs (210A, 210B) in the radio access network cell(110) ; and receiving (312) , at the network node device(220) from the user device (200) , a signal for the one or more TRPs (210A, 210B) based on at least one of the cell identifier or the one or more TRP indices, wherein : the synchronization signal information comprises one or more TRP specific synchronization signal blocks, SSBs; and the transmitting (311) the synchronization signal information comprises transmitting the one or more TRP specific SSBs from the specific TRP of the one or more TRPs (210A, 210B) .

15. An apparatus, comprising means for carrying out the method (310) according to claim 14.

16. A computer program comprising instructions for causing a network node device to perform at least the following: transmitting to a user device synchronization signal information, wherein the synchronization signal information comprises at least one of a cell identifierof a radio access network cell or one or more transmission and reception point , TRP, indices of one or more TRPs in the radio access network cell ; and receiving from the user device a signal for the one or more TRPs based on at least one of the cell identi fier or the one or more TRP indices , wherein : the synchroni zation signal information comprises one or more TRP specific synchroni zation signal blocks , SSBs ; and the transmitting the synchroni zation signal information comprises transmitting the one or more TRP speci fic SSBs from the speci f ic TRP of the one or more TRPs .

Images