The present invention relates to the field of telecommunications. Within this field, the invention relates more particularly to methods of communicating system information relating to the access network. It applies in particular to portable telecommunications devices.

Prior art

An access network generally consists of several base stations which allow a user equipment (UE: User Equipment) also called later terminal or UE, to have access to a telecommunications network and to establish a connection to exchange data.

A powered-on terminal is either in standby mode (idle) or in connected mode

(connected) to the network.

The standby mode is such that no radio or network resources are allocated to the user equipment. The terminal is not attached to any base station but is located by the network in a region containing several cells (Registration Area). It has no communication established to transmit data (DATA).

A cell schematically represents an area covered by a base station (BS: Base Stations) for a given radio access technique (RAT: Radio Access Technology) knowing that a base station can simultaneously have several cells, for example when is equipped with several directional antennas.

As part of the work carried out within 3GPP which led to version 15 of the so-called 5G standard, two main mechanisms have been defined for a terminal to select the cell on which it will camp in standby mode: the cell selection and the cell re-selection mechanism.

The selection mechanism is used by a terminal which is not yet camping on a cell. The re-selection mechanism is used by a terminal which is already camping on a cell. This re-selection can take place on the same radio frequency RF (Radio Frequency), the mechanism is called intra-frequency, on different RF radio frequencies, the mechanism is called inter-frequency (inter-frequency) or between different radio access techniques, the mechanism is said to be inter-RAT.

We say that a terminal camps on a cell A if it reads the system information broadcast by cell A (which among other things gives it the configuration of the paging channel of cell A) and if it listens to the “paging” channel ( broadcast to all the cells of the registration area) informing it of a communication intended for it from cell A. Furthermore, a terminal camping on cell A proceeds, following a request from a high layer (application layer) or following receipt of a notification of a paging message from cell A, on initial access to cell A to establish a communication.

During the cell selection or reselection mechanism, the terminal attempts to detect the SS synchronization signals. The SS synchronization signals consist of the primary synchronization signal PS S (Primary Synchronization Signal) and the secondary synchronization signal SSS (Secondary Synchronization Signal). The detection of SS synchronization signals (PSS and SSS) allows a terminal to synchronize in time and frequency and to decode the PBCH (Physical Broadcast Channel). The PBCH has a given periodicity and occupies time-frequency resources known in advance by the terminal.

In 5G, the physical PBCH channel is transmitted together with the synchronization signals (PSS and SSS). According to the terminology of the 5G specifications, an SSB block (SS / PBCH block) groups the SS synchronization signals and the PBCH physical broadcast channel.

For each of the cell selection and re-selection mechanisms, the terminal must decode the master information block MIB (Master Information Block) contained in the PBCH (which is part in 5G of an SSB block). The MIB information block gives the information needed by the terminal UE to be able to receive and decode a certain system information block, SIB1 in LTE and RMSI in 5G (corresponding to SIB1 and SIB2 of LTE) later called SIB1. The SIB1 comprises the identity of the public land mobile network PLMN (Public Land Mobile Network) and the identity of the physical cell, Cell-id.

When selecting a cell, the terminal decodes system information block 1, SIB1, of each detected cell. The terminal then camps on the cell selected via the selection mechanism as a function of the information contained in the blocks SIB1 of the cells detected.

When re-selecting a cell, the terminal is already camping on a cell. It must decode other system information blocks SIBs transmitted by the cell on which it camps which have a lower periodicity or which are transmitted at its request (SIBs transmitted on demand) knowing that the block SIB1 gives information to receive and decode the other SIBs system information blocks.

The so-called 4G LTE specifications do not use the term SSB block. However, LTE uses SS sync signals including PSS and SSS and uses PBCH. The transmission of SS and PBCH according to LTE follows a pattern with fixed periodicity as well as frequency positioning. The periodicity of the synchronization signals SS is thus 5 ms while that of the PBCH is 10 ms. For the re-selection of inter RAT cell re-selection between LTE and NR, according to the 4G TS36.331 V15.4.0 specifications, section 6.3.1, System information blocks, a single periodicity value per frequency of the SSBs of the neighboring 5G cells is broadcast by the SIB24 system information block. This single value per frequency is noted "measTimingConfig" in block SIB24. By "frequency",

The transmission of S SB blocks according to 5G NR specifications is carried out according to a certain time-frequency pattern. The pattern is repeated at a certain periodicity taken from a set of determined values: 5, 10, 20, 40, 80 and 160 ms with a default value of 20 ms. Figure 1 illustrates for a periodicity of 20 ms and for two different values ​​of spacing between SCS subcarriers the possible positions of the SSB blocks in accordance with technical specification 38.213 of 5G. An SSB burst called SS burst set is confined over a maximum duration of 5 ms every 20 ms and consists of several SSB blocks, each SSB block being mapped in time on four OFDM symbols. In FIG. 1 the 1 ms rectangles with a pattern of dots represent the subframes having SSB blocks forming a burst. The flexibility on the choice of the periodicity of the SSB blocks introduced in the 5G NR specifications has led to adapting to a certain extent the cell re-selection mechanism by providing for the broadcast by the cell on which the terminal is camped of a value of periodicity associated with the transmission of SSBs from neighboring cells for a frequency. This adaptation attempts to cover the case where the transmission periodicity of SSBs from neighboring cells is adjusted to a value other than the default value of 20ms. Thus, according to the technical specification of 3 GPP TS38.331 V15.4.0, section 6.3.1, System information blocks, a unique SSB periodicity value is broadcast by the system information block SIB2 to help an intra cell re-selection. -frequency, and a single SSB periodicity value is broadcast by the system information block SIB4 to aid inter-frequency cell reselection by frequency. For intra-frequency cell re-selection, the periodicity value SSB is denoted “smtc” in the block SIB2. For the inter-frequency cell reselection, the periodicity value SSB by frequency is noted "smtc" in the block SIB4.

Thus, the terminal which performs a cell re-selection can refer to these values ​​broadcast by the cell on which it is camping in order to adapt its synchronization procedure by using the single SSB periodicity value broadcast by one of the information blocks. system.

The specifications of the 5G network are such that 5G communications should benefit from a speed that is a thousand times greater than the previous generation. This performance is based in particular on the densification of base stations.

An increase in the number of base stations complicates the techniques for reducing the energy consumption of telecommunications networks. In order to be able to put some of these base stations on standby (ASM: Advanced Sleep Mode), a network operator must be able to control the load between the cells in his network. In addition, to increase the efficiency of placing a station on standby, the operator has an interest in using the SSB as long as possible to extend standby ie 160 ms.

To control the load on an operator's access network, it is essential that the terminals are camped on the right cells, ie those which allow the operator's criteria for proper management of his network to be respected. During a selection or a re-selection, the terminal attempts to detect the energy at the frequency positions of the SSBs specified by the standard over a default window of 20ms. In the absence of sufficient detected energy, the terminal can conclude that there is no network or that there is no SSB transmitted during its measurement window of 20 ms.

It happens that a terminal may not identify a cell A whose SSB periodicity is greater than 20ms if its measurement window of 20ms does not coincide with a transmission of at least one SSB of cell A. The terminal goes by against finding a B cell with a periodicity less than or equal to 20ms (which ensures that at least one SSB is transmitted in any 20ms measurement window) with certainty if the terminal is under its coverage. In the absence of detection of the cell, the terminal obviously cannot select it. This risk of non-selection is therefore a serious obstacle to the implementation by the operator of putting base stations on standby with an SSB rate of 160 ms.

Once camped on cell B, the terminal can attempt a cell re-selection, for example to find another higher priority cell (the priorities of the different frequencies chosen by the operator are broadcast in the SIBs relating to the re-selection of cell). The terminal can detect with certainty the cell A if the cell B broadcasts in its SIBs a periodicity value fixed at 160 ms. As only one periodicity value can be broadcast by the SIBs, this implies that the terminal scans systematically respecting this periodicity which imposes a measurement window of 160ms even if other cells may have a smaller periodicity and be of interest for the terminal. Indeed, if the terminal is configured with a window of 160ms,

There is therefore a need for a technique making it possible to improve the selection and re-selection procedures.

Disclosure of the invention

The invention proposes a communication method implemented by a base station having at least one cell, the base station forming part of a mobile access network comprising cells neighboring the cell. The process includes:

broadcasting at a first periodicity value of so-called SSB blocks intended for the

synchronization of a terminal and intended to allow the reception by this terminal of system information blocks of which at least one of these system information blocks comprises an identifier of at least one neighboring cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell.

A further subject of the invention is a communication method implemented by a terminal. The process includes:

the detection of so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

the decoding of these blocks to obtain information to be able to receive blocks

system information broadcast by the cell, at least one of these system information blocks comprising an identifier of at least one neighboring cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell,

the selection of this cell by the terminal.

According to a particular embodiment of the invention, the method implemented by a terminal comprises:

the detection of so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

the decoding of these blocks to obtain information in order to be able to receive system information blocks broadcast by the cell, at least one of these system information blocks comprising an identifier of at least one neighboring cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell,

the re-selection of the neighboring cell by the terminal if this neighboring cell has more priority. A further subject of the invention is a mobile terminal capable of implementing a method according to the invention. The terminal includes:

a receiver,

a detector for detecting so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

a decoder decoding these blocks to obtain information in order to be able to receive by the receiver system information blocks broadcast by the cell, at least one of these system information blocks comprising an identifier of at least one neighboring cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell,

a microprocessor for selecting or re-selecting the neighboring cell by the terminal if this neighboring cell has higher priority.

A further subject of the invention is a base station capable of implementing a method according to the invention. The base station includes:

a transmitter for broadcasting at a first periodicity value SSB blocks intended for the synchronization of a terminal and intended to allow the reception by this terminal of system information blocks of which at least one of these system information blocks comprises an identifier of at least one neighboring cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell.

A further subject of the invention is a digital signaling signal transmitted or received comprising so-called SSB blocks broadcast at a first periodicity value intended for the synchronization of a

terminal and intended to allow the reception by this terminal of system information blocks of which at least one of these system information blocks comprises an identifier of at least one neighboring cell of a cell, a second periodicity value of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell.

A terminal within the radio coverage of the cell can receive the SSB blocks broadcast by this cell. The primary utility of these SSB blocks is to allow the terminal to synchronize with the cell. These SSB blocks also allow the terminal to identify a neighboring station with higher priority than the cell and to search for it efficiently by providing the terminal with sufficient information, ie the identifier of this neighboring cell, the frequency position of an SSB block of this neighboring cell as well as the periodicity value of the SSB blocks broadcast by this neighboring cell, in order to finally select or re-select it easily. Since the addition of broadcast information has a cost (in time and frequency resources used, in energy required to manage this information), the number of information added is limited. Thus, the identifier of a cell, the frequency position of its SSB blocks and the periodicity of its SSB blocks can optionally be added for a second neighboring cell. The addition for other neighboring cells beyond the second is not possible for reasons of cost if this addition occurs in the system information block 1 SIB1.

According to a particular embodiment of the invention, the neighboring cells are synchronous with the cell and the at least one of these system information blocks further comprises a temporal positioning of these SSB blocks broadcast by this neighboring cell.

In a transmission context based on several beams or based on a single beam (which can be repeated in several SSBs), SSB blocks are transmitted in bursts (SS burst set) during a certain window (of maximum duration 5 ms for the specifications NR of 3GPP but the frame number, System Frame Number in English, which may contain SSB blocks is not specified in the standard). The number L of possible SSB blocks in a burst depends on the frequency band (band below 3GHz L is equal to 4, band between 3 and 6GHz L is equal to 8, band between 6 and 53GHz L is equal to 64) . The set of possible time locations (Time location) of the SSB blocks among a burst of synchronization signals (SS burst set) depends on OFDM numerology (OFDM numerology) which in most cases is uniquely identified by the frequency band. Knowing the temporal positioning of the SSB blocks broadcast by the neighboring cell (frame number, position (s) occupied in the frame) thus allows the terminal to position itself exactly at the right time to receive and decode these blocks. Selection or re-selection is therefore even more efficient.

According to a particular embodiment of the invention, at least one of these system information blocks is a so-called SIB1 block and the cell is of the 4G or 5G type.

According to a particular embodiment of the invention, at least one of these system information blocks is a so-called SIB24 block, the cell is of the 4G type, the neighboring cell is of the 5G type.

According to a particular embodiment of the invention, at least one of these system information blocks is a so-called SIB3 block, the cell and the neighboring cell are of the 5G type.

According to a particular embodiment of the invention, at least one of these system information blocks is a so-called SIB4 block, the cell and the neighboring cell are of the 5G type.

List of Figures

[Fig 1] FIG. 1 is a diagram illustrating the broadcasting of SSB blocks at a periodicity of 20 ms for two different values ​​of spacing between SCS subcarriers,

[Fig 2] Figure 2 is a flowchart of a communication method according to the invention implemented by a base station,

[Fig 3] Figure 3 is a flowchart of a communication method according to the invention implemented by a terminal,

[Fig 4] Figure 4 is a diagram of an example of an access network implementing the invention, [Fig 5] Figure 5 is a diagram of the simplified structure of a base station according to l invention capable of implementing a communication method according to the invention,

[Fig 6] FIG. 6 is a diagram of the simplified structure of a terminal according to the invention capable of implementing a communication method according to the invention.

Description of an embodiment of the invention

The general principle of the invention is based on the broadcasting by a cell of a pointer to a higher priority cell so that a terminal can select or re-select this higher priority cell even if the latter broadcasts its SSB blocks at a higher frequency. larger than the default size of the terminal synchronization window.

The pointer groups together several pieces of information: a Cell-Id identifier of a neighboring cell with a higher priority called secondary idle cell, the GSCN position in frequency of the SSB blocks of this neighboring cell and the T SSB value of periodicity of the SSB blocks broadcast by this neighboring cell .

The priority between cells is defined by the operator and is broadcast by the SIBs relating to cell re-selection. In a context where the cell and the neighboring cell are synchronized, the pointer can also comprise the temporal positioning of the SSB blocks broadcast by this neighboring cell.

Of course, the cell can broadcast several pointers to several neighboring cells with higher priority. However, the number of pointers is a function of the cost generated by the distribution of these pointers.

FIG. 2 represents a flowchart of a communication method according to the invention implemented by a base station. The base station has at least one cell. The base station is part of a mobile access network comprising neighboring cells of this cell.

The method 1 comprises the broadcasting 11 at a first periodicity value of so-called SSB blocks intended for the synchronization of a terminal and intended to allow the reception by this terminal of system information blocks. At least one of these system information blocks includes a

Cell-Id identifier of at least one neighboring cell, a second value T SSB of periodicity of SSB blocks broadcast by this neighboring cell and a GSCN position in frequency of an SSB block of this neighboring cell.

According to one embodiment, the neighboring cells are synchronous with the cell. In this case, the at least one of these system information blocks further comprises a temporal positioning T0 of these SSB blocks broadcast by this neighboring cell.

FIG. 3 represents a flowchart of a communication method according to the invention implemented by a terminal. The terminal wants to communicate via an access network. The access network includes at least one base station with at least one cell. The cell has one or more neighboring cells which belong either to the same base station or to different base stations which may be co-located.

Method 2 implemented by the terminal comprises:

the detection 21 of so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

the decoding 22 of these blocks to obtain information in order to be able to receive 23 of the system information blocks broadcast by the cell, at least one of these system information blocks comprising a Cell-Id identifier of at least one neighboring cell, a second value T SSB of periodicity of SSB blocks broadcast by this neighboring cell and a GSCN position in frequency of an SSB block of this neighboring cell,

the selection 24 of the neighboring cell by the terminal if this neighboring cell has more priority or the selection 24 by the terminal of the cell.

According to an exemplary implementation illustrated by FIG. 4, the operator of a telecommunications system has deployed cells of the 4G type and of the 5G type. A first 5G cell operates with a band A and with broadcasting of the SSB blocks at a periodicity greater than the default value of 20ms, for example 160ms. The choice by the operator of a periodicity of 160ms can be motivated by the implementation of a standby mode called ASM (Advanced Sleep Mode) of the base station BS with which the 5G cell is associated. In fact, the higher the broadcast frequency of the SSB blocks, the longer and deeper the standby can be. For example, the “IEEE Standards Association” has defined 3 standby modes with a minimum standby time of 71ps, 1ms and 10ms respectively.

A second 5G cell co-located with the first 5G cell operates with a B band and with a broadcast of the SSB blocks at a periodicity equal to the default value of 20ms. Another co-located cell can be a 4G cell operating in a C band with broadcast of the SSB blocks at a periodicity equal to the default value of 5ms.

The first 5G cell is the neighboring cell with a higher priority known as the secondary idle cell compared to the co-located cells.

The UE terminal can initially camp on the second 5G cell in the B-band or on the other

4G cell in band C. The terminal has therefore detected the SSB blocks broadcast by one of these co-located cells and is therefore synchronized with one of these co-located cells. The decoding of these SSB blocks enables it to obtain information in order to be able to receive system information blocks broadcast by this cell on which it is synchronized.

By receiving these SIB system information blocks, the terminal is aware of the Cell-Id identifier of the first 5G cell, the value, 160 ms, the periodicity of the SSB blocks broadcast by this neighboring cell and the frequency position d 'an SSB block of this neighboring cell.

The Cell-Id identifier corresponds to the physical cell identifier of the 3GPP NR specifications. The frequency position of an SSB block is given by the number of the synchronization channel called “GSCN: Global Synchronization Channel Number” in the NR specifications of the 3GPP.

The terminal then adjusts its synchronization window to this value of 160 ms and positions it in frequency knowing the position in frequency of an SSB block. Optionally, the terminal also has knowledge via one of the system information blocks SIB of the temporal positioning of these SSB blocks broadcast by this neighboring cell, which allows it to position its synchronization window in time.

The terminal can thus reliably detect and with a high success rate the SSB blocks of the priority neighboring cell and synchronize on this cell and thus perform a selection (if the pointer is in SIB 1) or re-selection of this cell. neighboring cell.

The simplified structure of a base station according to the invention conforming to a first protocol, for example 4G or 5G, and capable of implementing a transmission method according to the invention is illustrated in FIG. 5.

The base station BS comprises a microprocessor mR whose operation is controlled by the execution of a program Pg whose instructions allow the implementation of a communication method according to the invention, a transmitter EM, a memory Mem comprising a buffer memory.

On initialization, the code instructions of the program Pg are for example loaded into the buffer memory Mem before being executed by the processor mR. The mR microprocessor controls the transmitter.

The transmitter EM broadcasts the SSB blocks at a first periodicity value. These SSB blocks are intended for the synchronization of a terminal and are intended to allow the reception by this terminal of SIB system information blocks. The transmitter has knowledge as input of the Cell-Id identifier of at least one neighboring cell, of the second value T SSB of periodicity of SSB blocks broadcast by this neighboring cell and of the GSCN position in frequency of an SSB block of this neighboring cell. At least one of the system information blocks SIB comprises the Cell-Id identifier of at least the neighboring cell, the second value T SSB of periodicity of SSB blocks broadcast by this neighboring cell and the GSCN position in frequency of a block SSB of this neighbor cell.

The simplified structure of a terminal according to the invention capable of implementing a communication method according to the invention is illustrated by FIG. 6.

The terminal UE comprises a microprocessor mR whose operation is controlled by the execution of a program Pg whose instructions allow the implementation of a communication method according to the invention, a Mem memory comprising a buffer memory, a detector DET, a DEC decoder, a REC receiver.

On initialization, the code instructions of the program Pg are for example loaded into the buffer memory Mem before being executed by the microprocessor mR. The mR microprocessor controls the DET detector, the DEC decoder and the REC receiver.

The detector DET receives as input blocks called SSB broadcast by a cell at a first periodicity and system information blocks SIB broadcast by the cell. The DET detector detects SSB blocks and their detection allows the terminal to synchronize with the cell.

The decoder DEC receives the SSB blocks as input and decodes them to obtain information in order to be able to receive by the receiver REC system information blocks SIB broadcast by the cell.

The reception by the receiver REC of the system information blocks SIB enables the terminal to have knowledge of the Cell-Id identifier of at least one neighboring cell, of a second value T SSB of periodicity of the SSB blocks broadcast by this neighboring cell and a GSCN position in frequency of an SSB block of this neighboring cell.

Knowledge of the Cell-Id identifier of at least one neighboring cell, of a second value T SSB of periodicity of the SSB blocks broadcast by this neighboring cell and of a GSCN position in frequency of an SSB block of this cell neighbor allows the microprocessor mR to select or re-select this neighboring cell if it has higher priority than the cell.

Consequently, the invention also applies to a computer program or more, in particular a computer program on or in an information medium, suitable for implementing the invention. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code such as in a partially compiled form, or in any other form. desirable for implementing a method according to the invention.

The information medium can be any entity or device capable of storing the program. For example, the medium may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or else a means

magnetic recording, for example a floppy disk or hard disk.

On the other hand, the information medium can be a transmissible medium such as an electrical or optical signal, which can be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can in particular be downloaded from an Internet type network.

Alternatively, the information medium can be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

CLAIMS

1. Method (1) of communication implemented by a base station having at least one cell, the base station forming part of a mobile access network comprising neighboring cells of the cell, the method comprising:

the broadcast (11) at a first periodicity value of so-called SSB blocks intended for the synchronization of a terminal and intended to allow the reception by this terminal of system information blocks (SIB) including at least one of these blocks of system information comprises an identifier (Cell-Id) of at least one neighboring cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a position (GSCN) in frequency of an SSB block of this neighboring cell.

2. Method (1) of communication according to the preceding claim such that the neighboring cells are synchronous with the cell and such that at least one of these system information blocks further comprises a temporal positioning (T0) of these broadcast SSB blocks. by this neighboring cell.

3. Method (2) of communication implemented by a terminal characterized in that it

understand :

the detection (21) of so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

the decoding (22) of these blocks to obtain information in order to be able to receive (23) system information blocks broadcast by the cell, at least one of these blocks

system information comprising an identifier (Cell-Id) of at least one neighboring cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this cell neighbor,

the selection (24) of this cell by the terminal.

4. Method (2) of communication implemented by a terminal characterized in that it

understand :

the detection (21) of so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

the decoding (22) of these blocks to obtain information in order to be able to receive (23) system information blocks broadcast by the cell, at least one of these blocks

system information comprising an identifier (Cell-Id) of at least one neighboring cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a position (GSCN) in frequency of an SSB block of this neighboring cell,

the re-selection (24) of the neighboring cell by the terminal if this neighboring cell has higher priority.

5. Method (1) of transmission according to one of claims 1, 2 and 4 such that at least one of these system information blocks is a so-called SIB1 block and the cell is of the 4G or 5G type.

6. Method (1) of transmission according to one of claims 1, 2 and 4 such that at least one of these system information blocks is a so-called SIB24 block, the cell is of 4G type, the neighboring cell is of type 5G.

7. Transmission method (1) according to one of claims 1, 2 and 4 such that at least one of these system information blocks is a so-called SIB3 block, the cell and the neighboring cell are of 5G type.

8. Method (1) of transmission according to one of claims 1, 2 and 4 such that at least one of these system information blocks is a so-called SIB4 block, the cell and the neighboring cell are of 5G type.

9. Base station (BS) characterized in that it comprises:

a transmitter (EM) for broadcasting at a first periodicity value S SB blocks intended for the synchronization of a terminal and intended to allow the reception by this terminal of system information blocks (SIB) including at least one of these blocks system information comprises an identifier (Cell-Id) of at least one neighboring cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a position (GSCN) in frequency of an SSB block of this neighboring cell.

10. Mobile terminal (EU) comprising:

a receiver (REC),

a detector (DET) for detecting (21) so-called SSB blocks broadcast by a cell at a first periodicity so that the terminal is synchronized with this cell,

a decoder (DEC) decoding (22) of these blocks in order to obtain information in order to be able to receive (23) by the receiver (REC) system information blocks broadcast by the cell, at least one of these system information blocks comprising an identifier (Cell-Id) of at least one neighboring cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a frequency position of an SSB block of this neighboring cell,

a microprocessor (mR) for selecting or re-selecting (24) the neighboring cell by the terminal if this neighboring cell has higher priority.

11. Computer program on an information medium, said program comprising

Program instructions suitable for implementing a method according to any one of claims 1 and 2 when said program is loaded and executed in a base station.

12. Information carrier comprising program instructions suitable for implementing a method according to any one of claims 1 and 2, when said program is loaded and executed in a base station.

13. Computer program on an information medium, said program comprising

program instructions adapted to the implementation of a method according to any one

of claims 3 to 7 when said program is loaded and executed in a mobile terminal.

14. Information carrier comprising program instructions suitable for implementing a method according to any one of claims 3 to 7, when said program is loaded and executed in a mobile terminal.

15. Digital signal transmitted or received comprising so-called S SB blocks broadcast at a first periodicity value intended for the synchronization of a terminal and intended to allow the reception by this terminal of system information blocks (SIB), at least one of which of these system information blocks comprises an identifier (Cell-Id) of at least one neighboring cell of a cell, a second value (T SSB) of periodicity of SSB blocks broadcast by this neighboring cell and a position (GSCN) in frequency of an SSB block of this neighboring cell.