WO2019168451A1

WO2019168451A1 - Method and node(s) for providing synchronization signals of a wireless communication network

Info

Publication number: WO2019168451A1
Application number: PCT/SE2018/050197
Authority: WO
Inventors: Ulf HÄNDEL; Pål FRENGER; Reza Moosavi; Peter LOBORG
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2018-03-01
Filing date: 2018-03-01
Publication date: 2019-09-06

Abstract

Method and one or more nodes (210; 230; 240; 310; 510) for providing synchronization signals of a wireless communication network (200). Transmission is initiated (701) of a first set of radio beams (212a-b; 312a-d; 512a-d) comprising Synchronization Signal Blocks, "SSBs", respectively, for enabling a wireless device (220; 320; 520) receiving such SSB to establish connection with the wireless communication network (200). Said SSBs of the first set belong to a certain sequence of SSBs and thereby associated with SSB sequence numbers, respectively. Transmission is initiated (702) of a second set of radio beams (213a-b; 313a-d; 513a-d) comprising SSBs, respectively, also belonging to said certain sequence. The second set comprises at least one changed radio beam (213b; 313d; 513a-d) comprising a SSB associated with the same sequence number as a SSB of a radio beam (212b; 312d; 512a-d) of the first set but covering another area, whereby a total area (218; 318; 518) covered by the first set and second set in combination becomes larger than covered by each set alone.

Description

METHOD AND NODE(S) FOR PROVIDING SYNCHRONIZATION SIGNALS OF A WIRELESS COMMUNICATION NETWORK

TECHNICAL FIELD

Embodiments herein relate to a method and one or more nodes for providing synchronization signals of a wireless communication network, e.g. telecommunication network.

BACKGROUND

Communication devices such as wireless communication devices, that simply may be named wireless devices, may also be known as e.g. user equipments (UEs), mobile terminals, wireless terminals and/or mobile stations. A wireless device is enabled to communicate wirelessly in a wireless communication network, that alternatively e.g. may be named cellular communication network, wireless

communication system, radio communication system, cellular radio system, cellular network or cellular communication system. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone and/or between a wireless device and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the cellular communication network. The wireless device may further be referred to as a mobile telephone, cellular telephone, laptop, Personal Digital Assistant (PDA), tablet computer, just to mention some further examples. Wireless devices may be so called Machine to Machine (M2M) devices or Machine Type of Communication (MTC) devices, i.e. devices that are not associated with a conventional user. The wireless device may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data, via the RAN, with another entity, such as another wireless device or a server. The wireless communication network covers a geographical area in which radio coverage is provided and enables wireless devices to connect and communicate in the network. The area may be divided into subareas, e.g. cell areas, wherein each subarea is served by at least one base station, or Base Station (BS), e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. "eNB", "eNodeB", "NodeB", "B node", or BTS (Base Transceiver Station), gNB, depending on the technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The base station at a base station site typically provides radio coverage for one or more cells. A cell is typically identified by one or more cell identities and may be associated with a geographical area where radio coverage for that cell is provided by the base station at the base station site. Cells may overlap so that several cells cover the same geographical area. By the base station providing or serving a cell is meant that the base station provides radio coverage such that one or more wireless devices located in the geographical area where the radio coverage is provided may be served by the base station in said cell. When a wireless device is said to be served in or by a cell this implies that the wireless device is served by the base station providing radio coverage for the cell. One base station may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the wireless device within range of the base stations.

UMTS is a 3G, or third generation, mobile communication system, which evolved from Global System for Mobile communications (GSM) that belongs to the so called 2nd generation or 2G. UMTS provides improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for wireless devices. High Speed Packet Access (HSPA) is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink PacketAccess (HSUPA), defined by 3GPP, that extends and improves the performance of existing 3G mobile telecommunication networks utilizing the WCDMA. Such networks may be named WCDMA/HSPA.

The 3rd Generation Partnership Project (3GPP) has further evolved the UTRAN and GSM based radio access network technologies, for example into evolved UTRAN (E-UTRAN) used in Long Term Evolution (LTE) that is a 4G, i.e. 4^th generation, mobile communication system.

3GPP is also involved in standardizing yet another new generation wide area networks, which may be referred to as fifth generation (5G). 5G New Radio (5G NR), or simply NR, is the new radio air interface being developed for 5G. However, NR may also be used to denote 5G in general. Another acronym being used to denote 5G is Next Generation (NG). The first release of a set of 5G standard specifications was Release 15, in late 2017. See e.g.“NG-RAN - Architecture description”, 3GPP TS 38.401 v.15.0.0. for an overview of the architecture, and e.g.“NR Radio Resource Control (RRC) protocol specification”, 3GPP TS 38.331 v.15.0.0.

A design principle for 5G is ultra-lean design. This i.a. implies that "always on signals" shall be avoided in the network as much as possible. A benefit from this design principle is to enable lower network energy consumption, better scalability, higher degree of forward compatibility, lower interference from system overhead signals and consequently higher throughput in low load scenario, and also improved support for user centric beam-forming.

Advanced Antenna Systems (AAS) is an area where technology has advanced significantly in recent years and where it is also foreseen a rapid technology development also in the years to come. Advanced antenna systems in general, and massive Multiple Input Multiple Output (MIMO) transmission and reception in particular, are beneficially used for 5G.

As beam-forming becomes increasingly popular and capable, it becomes natural to use it not only for transmission of data but also for transmission of control information and synchronization signals.

One of the distinguishing characteristics of 5G, or NR as will be used in the following, is the frequency range of NR deployments. More precisely, NR can allow for frequency deployments from 0 up to 100 GHz. In comparison to the current frequency bands allocated to LTE, some of the new bands will have much more challenging propagation properties such as lower diffraction and higher outdoor and indoor penetration losses. Consequently, signals will have less ability to propagate around corners and penetrate walls. In addition, in high frequency bands atmospheric, such as rain, attenuation and higher body losses render the coverage of NR signals even spottier. Fortunately, the operation in higher frequencies makes it possible to use smaller antenna elements as well as antennas with larger maximum electrical distance between antenna elements compared to antennas with the same physical size at lower frequencies. This facilitates beamforming, where the larger maximum electrical distance between antenna elements in combination with multiple antenna elements are used to form narrower beams with higher antenna gain than at lower frequencies and thereby compensate for the challenging propagation properties at higher frequencies. A beam is considered narrower than another beam if its radiation is focused in a smaller, possibly discontinuous, total angular range than the other beam. For these reasons, it is widely accepted that NR will massively rely on beamforming to provide coverage, which sometimes make people call it a beam-based system.

Using beamforming, while helping in mitigating some of the effects of higher frequency deployments, creates also some challenges that should be addressed.

In for example LTE, a UE discovers a cell and perform Radio Resource

Management (RRM) measurements based on signals transmitted in an omnidirectional or cell-wide, also known as sectored, manner. In NR, on the other hand, the UE should be able to perform cell discovery and RRM measurements on signals that can be beamformed.

To cope with beamforming, a certain signal structure is planned for NR to carry synchronization signals for cell discovery and RRM measurements, in particular directed to UEs in Radio Resource Control (RRC) idle mode and RRC connected mode, i.e. RRCJDLE and RRC_CONNECTED UEs. See e.g.“NR Physical channels and modulation”, 3GPP TS 38.211 v.15.0.0, in particular chapter 7.4.3. However, in RRC_CONNECTED, additional reference signals, such as Channel State Information Reference Signal (CSI-RS), can also be used. In any case, for NR, said signal structure is referred to as a Synchronization Signals (SS) Block Set, or SSB set. Within one SS Block (SSB), an NR Primary Synchronization Signal (NR-PSS), an NR

Secondary Synchronization Signal (NR-SSS) and an NR Physical Broadcast Channel (NR-PBCH) are transmitted. More specifically, a SSB consists of four consecutive Orthogonal Frequency Division Multiplex (OFDM) symbols, where in the first and the third OFDM symbols, NR-PSS and NR-SSS are transmitted, respectively, while NR- PBCH is transmitted in the second and the fourth OFDM symbols. A UE shall from an SSB be able to identify at least OFDM symbol index, slot index in a radio frame and radio frame number. A single set of possible SSB time locations, e.g. with respect to radio frame of 10 msec duration, is specified per frequency band. In other words, it is specified per frequency band where the SSBs shall and will occur. One slot may consist of e.g.14 OFDM symbols and it is thus defined per frequency band which of these OFDM symbols per slot are allowed locations of SSBs. The duration of one slot is also frequency dependent.

One or multiple SSB(s) further compose an SS burst set, or series, where the maximum number of allowed SSBs, L, within an SS burst set is frequency dependent: • For frequency range up to 3 GHz, L is 4.

• For frequency range from 3 GHz to 6 GHz, L is 8.

• For frequency range from 6 GHz to 52.6 GHz, L is 64.

The starting locations of SSBs within a SS burst set are pre-defined, starting from a first slot. As the number of the SS blocks within a SS burst can vary, the duration of a SS burst might vary as well, but should always confined within 5 ms, regardless the number of SSBs. From physical layer specification perspective, at least one periodicity of SS burst set is supported. From UE perspective, the SS burst set transmission is typically periodic, i.e. repeated periodically. At least for initial cell selection, a UE may assume a default periodicity of SS burst set transmission for a given carrier frequency, e.g. a periodicity that is one of 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms. By default, the UE may neither assume the gNB, i.e. a node corresponding to a base station in NR, transmits the same number of physical beam(s), nor the same physical beam(s) across different SS-blocks within an SS burst set.

SUMMARY

In view of the above, an object is to provide one or more

improvements regarding provision of synchronization signals in a wireless

communication network, which improvements should be compatible with such signal structure for synchronization signals as discussed above and should be suitable for NR communication networks.

According to a first aspect of embodiments herein, the object is achieved by a method, performed by one or more nodes, for providing synchronization signals of a wireless communication network. Said one or more nodes initiate transmission of a first set of radio beams comprising Synchronization Signal Blocks (SSBs),

respectively, for enabling a wireless device receiving such SSB to establish connection with the wireless communication network. Said SSBs of the first set belong to a certain sequence of SSBs and are thereby associated with SSB sequence numbers, respectively. Said one or more nodes also initiate transmission of a second set of radio beams comprising SSBs, respectively, also belonging to said certain sequence of SSBs. The second set comprises at least one changed radio beam comprising a SSB associated with the same sequence number as a SSB of a radio beam of the first set but covering another area, whereby a total area covered by the first set and second set in combination becomes larger than covered by each set alone.

According to a second aspect of embodiments herein, the object is achieved by a computer program comprising instructions that when executed by a processing circuit causes said one or more nodes to perform the method according to the first aspect.

According to a third aspect of embodiments herein, the object is achieved by a carrier comprising the computer program according to the second aspect, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

According to a fourth aspect of embodiments herein, the object is achieved by one or more nodes for providing synchronization signals of a wireless communication network. Said one or more nodes are configured to initiate transmission of a first set of radio beams comprising Synchronization Signal Blocks (SSBs), respectively, for enabling a wireless device receiving such SSB to establish connection with the wireless communication network. Said SSBs of the first set belong to a certain sequence of SSBs and are thereby associated with SSB sequence numbers, respectively. Said one or more nodes are also configured to initiate transmission of a second set of radio beams comprising SSBs, respectively, also belonging to said certain sequence of SSBs. The second set comprises at least one changed radio beam comprising a SSB associated with the same sequence number as a SSB of a radio beam of the first set but covering another area, whereby a total area covered by the first set and second set in combination becomes larger than covered by each set alone.

Conventionally, a synchronization signal and e.g. a SSB with the same sequence number as in a preceding SS burst, would be retransmitted in a beam with the same coverage. However, according to embodiments herein, at least one changed beam means that one or more SSBs with the same sequence number are transmitted in different areas, enabling a larger total area to be covered than possible by one set of radio beams carrying the SSBs, but without necessarily having to transmit with higher power or causing higher energy consumption. A wireless device that else could not be reached, can be reached by changed radio beams. Embodiments herein thereby e.g. enable idle mode coverage in NR to be extended to become closer to that of the connected mode, thus reducing a mismatch that else typically would occur. Such mismatch may else e.g. cause a UE experiencing dropped calls and connections to be unable to reconnect to the network due to lack of idle mode coverage and thus lack of synchronization signals.

In general, use of certain radio beams that change coverage as in embodiments herein increases flexibility and versatility for how synchronization signal can be provided. This for example also includes situations where e.g. the number of SSBs that can be used in a certain time interval is limited, e.g. due to that the sequence is limited, such as owing to a limited number of SSBs of a SS burst set when the wireless communication network is or is based on 5G or NR.

Further advantages from embodiment herein e.g. include:

additional interference caused by transmission of NR-SS to achieve extended coverage can be kept low, and

it is enabled to reduce the time required to be able to use narrow connected mode radio beams.

Embodiments herein thus enable improved provision of synchronization signals.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail with reference to the appended schematic drawings, which are briefly described in the following.

Figure 1 is a block diagram schematically illustrating an example of a

wireless communication network and situation associated with a problem addressed by embodiments herein.

Figure 2a is a block diagram schematically depicting an example of a

wireless communication network in which embodiments herein may be implemented and also schematically illustrates transmission of radio beams with synchronization signals, in accordance with some embodiments herein.

Figure 2b schematically depicts timing relations between Synchronization Signal Blocks (SSBs) comprised in radio beams as shown in Figure 2a. Figure 2c illustrates in a schematic manner that in a sequence of SSBs, e.g. a SS burst set, SSB(s) with certain sequence numbers can be predefined for use in certain radio beams in accordance with embodiments herein.

Figure 3 is another block diagram schematically depicting transmission of radio beams with synchronization signals, in accordance with some embodiments herein, at six different time periods, T 1 -T6.

Figure 4 schematically depicts timing relations between SSBs comprised in radio beams as shown in Figure 3.

Figure 5 is yet another block diagram schematically depicting transmission of radio beams with synchronization signals, in accordance with some embodiments herein.

Figure 6a schematically depicts a first example of timing relations between SSBs comprised in radio beams as shown in Figure 5.

Figure 6b schematically depicts a second example of timing and frequency relations between SSBs comprised in radio beams as shown in Figure 5.

Figure 7 is a flowchart schematically illustrating embodiments of a method performed by one or more nodes.

Figure 8 is a functional block diagram for illustrating embodiments of said one or more nodes.

Figure 9 is a schematic drawing illustrating embodiment relating to computer program(s) and carriers thereof to cause said one or more nodes to perform method actions.

DETAILED DESCRIPTION

As part of the development towards embodiments herein, the situation indicated in the Background will first be further elaborated upon.

As mentioned above, by using beamforming and narrow beams, users can be reached at further distances than when using conventional wide beam transmissions. Given that the synchronization signals in NR, i.e. NR-SS, should be transmitted in a relatively short time interval and that they should cover a whole idle-mode coverage area, it is typically desirable to transmit them in wider beams than the beams used for data transmission. Flowever, it has been realized that this would result in that the idle mode cell coverage in NR-SS will be less than the achievable connected mode cell coverage. In other words, a UE outside the idle-mode coverage area cannot access the cell even though the cell could still serve it. This also means that if a connection for a UE is dropped in such an area, the UE will not be able to reconnect to the network from within that area.

Figure 1 illustrates such a situation, corresponding to what would be the case if the signal structure for NR synchronization signals as discussed in the Background would be applied“straight on” based on how synchronization signals have been provided in the prior art. A UE1 is within the coverage area of the four radio beams transmitting synchronization signals in 4 SSBs of a SS burst set with L=4. However, a UE2 is outside the coverage of the synchronization signals, i.e. outside idle-mode coverage, although it could be reached by data transmission, i.e. is inside connected mode coverage, using beamforming and a narrow beam. In the shown situation, the SS burst set is repeated every 20 ms and thus a SSB can be expected at any location in the coverage area every 20 ms.

Based on the above it has been identified a need to come up with a solution of how NR synchronization signals, i.e. SSBs, as discussed in the Background can be provided and be able to reach both a wireless device that is within a wide beam coverage area as above and a wireless device that is outside this area but that would still be within reach of data transmission using beamforming. The wireless device addressed by these synchronization signals may be wireless devices, or UEs, in so called RRC idle mode and/or RRC inactive and/or RRC connected mode, e.g. named RRCJDLE and/or RRCJNACTIVE and/or RRC_CONNECTED. Embodiments herein can thus be seen as removing or at least reducing the above indicated problem with mismatch between idle mode coverage and connected mode coverage.

Figure 2 schematically depicts, among other things, a simplified example of a wireless communication network 200, e.g. a telecommunication network, in which embodiments herein may be implemented. The wireless communication network 200 may e.g. be a NR communication network or at least a NR supporting and/or based communication network. The figure further shows an example of a wireless device 220 for wireless communication in the wireless communication network 200. The wireless communication network 200 comprises a radio network node 210 such as base station that in case of NR, or 5G, may be named gNB. The radio network node 210 may be part of a Radio Access Network (RAN) of the wireless communication network 200.

The figure also shows a further node 230 and a further network 240. The further node 230 may be located outside the wireless communication network 200, i.e. be an external node, as indicated in the figure, or alternatively (not indicated in the figure) be comprised in the wireless communication network 200 and thus be a network node thereof, e.g. a management node thereof. The further network node 230 may in principle be any node communicatively connected to the radio network node 210.

Likewise, the further network 240 may be located outside the wireless communication network 200, i.e. be an external network, as indicated in the figure, e.g. corresponding to a so-called computer cloud, often simply referred to as cloud, that may provide and/or implement services and/or functions relating to the wireless communication network 200. The further network 240 may in alternatively (not indicated in the figure) be comprised in the communication network 200 and thus e.g. correspond to a subnetwork thereof, e.g. a core network. It is implied that a network and the further network 240 comprises interconnected network nodes and may e.g. include the further node 230 as indicated in the figure. The further network 240 may in principle be any network communicatively connected to the radio network node 210.

Moreover, the figure additionally schematically illustrates transmission of radio beams with synchronization signals, in accordance with some embodiments herein. More particularly, the figure illustrates that the radio network node 210 transmits, at a time period TO, a radio beam 212a comprising a SSB named SSB0 and a radio beam 212b comprising a SSB named SSB1 . The radio beams 212a-b are part of a first set of radio beams 212a-b transmitted at time period TO. Further, as also indicated in the figure, the radio network node 210 transmits, at a time period T1 , a radio beam 213a comprising SSB0 and a radio beam 213b comprising SSB1 . The radio beams 213a-b are part of a second set of radio beams 213a-b transmitted at time period T 1 .

Radio beams are schematically illustrated in figures herein by their radio coverage areas. It can be noted that radio beams 212a and 213a have the same radio coverage area at TO and T 1 , i.e. in both sets, i.e. SSB0 is provided in the same area at TO and T1 . In contrast, radio beams 212b and 213b cover different areas at TO and T 1 , the coverage is thus changed between the sets. Thus, SSB1 is provided in different areas at TO and T 1 . However, as schematically illustrated in the figure, in combination the two sets, i.e. seen over both TO and T 1 , approximately cover a total coverage area 218 that is larger than covered by each set taken alone and larger than if both sets would be provided with only static radio beams, i.e. beams that do not change coverage between the sets. Provision of such static beams would correspond to the situation illustrated in Figure 1. The radio beams 212a and 213a at TO and T 1 with SSBO may be wide beams that are static and provide a more short range coverage as in Figure 1 , while the radio beams 212b and 213b with SSB1 may be more narrow, longer or extended range beams, e.g. provided by beamforming, and thereby be able to reach longer and e.g. reach the wireless device 220 that could not be reached by the radio beams 212a, 213a. The wireless device 220 would thus not receive any SSB at TO but would at least receive SSB1 at T1.

Above, and in general herein, SSBx denotes a certain SSB in a sequence of SSBs, e.g. at a position x in the sequence, i.e. x may denote the order of occurrence of the SSB in the sequence. In other words, x may denote a sequence number associated with the SSB and denoting the order of the SSB in the sequence. SSBO may thus indicate the first SSB of the sequence, SSB1 the second SSB of the sequence, etc. The sequence may correspond SSBs of a so-called SS burst set as discussed above, i.e. the sequence may at most comprise a certain number L of sequentially occurring SSBs, where L may be predefined and frequency dependent.

Attention is drawn to that Figure 2a is only schematic and for exemplifying purpose and that not everything shown in the figure may be required for all

embodiments herein, as should be evident to the skilled person. Also, a wireless communication network or networks that in reality correspond(s) to the wireless communication network 200, will typically comprise several further network nodes, such as base stations, etc., as realized by the skilled person, but which are not shown herein for the sake of simplifying.

Figure 2b schematically depicts timing relations between SSBs comprised in radio beams as shown in Figure 2a. In the figure, TO is shown as a time period 262 and T1 as a time period 263. It is exemplified that there is a predetermined period 250 between provision of the first set of radio beams 212a-b and the second set of radio beams 213a-b, which predetermined period e.g. may correspond to the 20 ms period illustrated in Figure 1 and may thus be associated with a requirement of how often synchronization signals should be provided in an idle mode coverage area. The predetermined period 250 may correspond to or be based on a periodicity of the SS burst set, i.e. SS burst set period. The figure can be considered to illustrate a situation with a SS burst set where L=2, i.e. there are two SSBs, SSBO and SSB1 , in a sequence corresponding to the burst set. The figure also illustrates that there is a repetition of the transmission of the sets with radio beams, i.e. there is pattern that is repeated and thus after a repeat period 270, SSB1 is again provided in the same area, here corresponding to radio beam 212b, etc. This can be viewed upon as if radio beams 212b and 213b with SSB1 are“moved” or“swept”, which in this example thus would back and forth between two positions and radio beam coverage areas where SSB1 is provided.

During the repeat period 270 there will be at least one SSB is receivable at any location within said total area 218, although in a coverage area of radio beams 212a, 213a, SSBO will be provided twice within the repeat period, while SSB1 will only be provided once in the coverage areas of radio beams 212b, 213b.

Figure 2c schematically illustrates that in a sequence of SSBs, e.g. a SS burst set, where certain SSB(s) with certain sequence numbers are predefined for use in radio beams that change coverage between sets of radio beams. The shown sequence comprises SSB1 to SSB_N+M or SSB1 ... SSB_N... SSB_N+M. There may be predefined or predetermined that an absolute or relative number of SSBs of a sequence, e.g. SS burst set, e.g. a certain, such as last, part of the sequence, are to be used by radio beams that change coverage between the sets and e.g. may be used to provide extended coverage compared to other radio beams of the sets. These SSBs may be identified by their sequence numbers and may e.g. be reserved and/or allocated for said use, which for example may be specified in a standard specification that may also indicate purpose and/or use of such SSBs.

In the example of Figures 2a-b, there may be L=2 and the sequence of Figure 2c would only consist of SSBO and SSB1 , i.e. L=N+M, where N=1 and M=1 and thus SSB1 is a SSB predefined for use in radio beams that change coverage between the sets, i.e. for radio beams 212b, 213b.

Figure 3 is another block diagram schematically depicting transmission of radio beams with synchronization signals, in accordance with some embodiments herein, this time at six different time periods, T1 -T6, to more clearly illustrate the principle discussed above in relation to Figures 2a-b. Figure 3 is supported by Figure 4 that schematically depicts timing relations between SSBs comprised in radio beams as shown in Figure 3.

Figures 3 and 4 should be readily understood in view of the similarities with what already has been discussed above and shown for Figures 2a-c, the following will therefore primarily focus on differences. Figure 3 shows a radio network node 310, e.g. gNB, that transmits six different sets of radio beams at different time periods, T 1 - T6, respectively. Each set comprise four radio beams comprising four SSBs, SSB0- SSB3, respectively. The SSBs are part of a SSB sequence that may correspond to a SS burst set. What is shown may thus correspond to a situation where L=4.

The radio network node 310 may correspond to the radio network node 210 and is comprised in a wireless communication network (not shown) that may be or correspond to the wireless communication network 200.

The figure illustrates that the radio network node 310: at a time period T 1 transmits a first set of radio beams 312a-d, at time period T2 transmits a second set of radio beams 313a-d, at time period T3 transmits a third set of radio beams 314a- d, at time period T4 transmits a fourth set of radio beams 314a-d, at time period T5 transmits a fifth set of radio beams 315a-d and at time period T6 transmits a sixth set of radio beams 316a-d. In Figure 4 the time periods T 1 -T6 are numbered as time periods 462-467.

In Figure 3, radio beams 312a-c to 317a-c comprising SSBs SSB0-SSB2, cover substantially the same area at all time periods T 1 -T6 and may thus be considered as static radio beams in said sets. On the other hand, radio beams 312d to 317d comprising SSB3 change between the sets and time periods T1 -T6 and may thus be considered as changed radio beams in said sets. The changed radio beams 312d to 317d have extended coverage compared to the other, static beams.

The radio beams 312d to 317d thus correspond to radio beams 212b to 213b in Figure 2a and radio beams 312a-c to 317a-c thus correspond to radio beams 212a to 213a in Figure 2a.

Similar as in Figure 2b, it is in Figure 4 exemplified a predetermined period 350 between provision of the first set of radio beams 312a-d and the second set of radio beams 313a-d, which predetermined period may correspond to the predetermined period 250 and e.g. the 20 ms period of previous examples. The predetermined period 350 may thus also here correspond to or be based on a periodicity of a SS burst set, i.e. SS burst set period, that contains the SSBs. Typically it is the same time period, here the predetermined period 350, between provision of each set of radio beams, i.e. the sets are provided with an equal time period between each set that may be given by the SS burst set periodicity.

Further, as shown, there is a total area 318 covered by said sets of radio beams during said repeat period 470. A wireless device 320, e.g. UE, that may correspond to the wireless device 220 and that may be in idle mode, is shown in the total area 318, but outside radio coverage provided by the static radio beams 312a-c to 317a-c. The wireless device 320 is thus within the radio coverage provided by the changed radio beam 317d with SSB3 at time period T6, but outside radio coverage provided by other radio beams of the sets. The wireless device 320 will thus at least be able to receive synchronization signals through SSB3 at T6 and thereby be able to connect to the wireless communication network that radio network node 310 is part of.

It is clearly seen that the changed beams 312d to 317d change position over the sets and time periods T1 -T6 in order to contribute to coverage of the total area 318, and that the change resemble that of a“sweep” and thus that said changed beams can be provided by beamforming where a radio beam is“swept” or provided at certain subsequent directions, e.g. given by angular directions, at different points in time, here at time periods T 1 -T6. After provision of the sixth set of radio beams 317a-d at time period T6, a transmission sequence of the sets of radio beams may be repeated, etc. This is illustrated by a repeat period 470 indicated in Figure 4. Flence, any wireless device within the total area 318 should be able to at least receive a SSB and synchronization signals once within the repeat period 470.

It should be noted that the radio beams, both static and changed beams, need not necessarily be transmitted or be“on” all the time during the time periods T1 -T6. At least from a perspective of SSB provision, it is sufficient that the radio beams are transmitted when the SSBs are to be provided, e.g. during a SSB sequence, such as during the SS burst sets, or at least when the SSB of each radio beam is to be provided according to the sequence. This is the case also for other examples herein. Flence, the radio beams may be transmitted or“on” quite frequently, but not necessarily all the time although they may be referred to as“always on” radio beams, at least the static radio beams. Any of the static radio beams in Figure 3 may appear as“on” a factor 6 more often for a wireless device (not shown) that is positioned so that it can receive both a static and a changed radio beam. In the above examples, e.g. of NR-SS transmission, the radio beams that change between the sets, i.e. changing radio beams, that typically are extended-range radio beams, can be considered to form or create an extended cell. However, at a given location, transmission of SSBs in such changed radio beam will be less frequent in time than transmission of SSBs in static radio beams. A wireless device that at a location is able to detect both a SSB of a changed beam and of a static beam, will thus be able to detect the SSB of the static beam with a smaller periodicity (e.g. every 20 ms or 5 ms) compared to the SSB of the changing radio beam that can be detected at a longer periodicity (e.g. every 160 ms or 20 ms).

A wireless device, e.g., the wireless devices 220 or 320, detecting the SSB of a changing radio beam may use a Random Access CHannel (RACH) resources associated with this SSB to connect to the radio network node transmitting the SSB, e.g. the radio network node 310 or 510.

It may be advantageous to configure wireless devices, e.g., the wireless devices 220 and 320, to be able to distinguish SSBs of changing radio beams from other SSBs, e.g. of static radio beams, and/or making these SSBs distinguishable from said other SSBs. The wireless devices are then enabled and can be configured to act differently when receiving such SSB compared to said other SSBs. This can e.g. be accomplished, at least partly, through predefined SSBs of SS burst set as discussed above in connection with Figure 2c. However, there are also other possibilities to accomplish this, e.g. identification of timing between the received SSBs, and/or it may be utilized timing knowledge of when certain SSBs in a SS burst set are transmitted. Further, there may be additional information in these SSBs.

Wireless devices, e.g., the wireless devices 220 and 320, may further be informed in advance about the existence of SSBs of changing radio beams, i.e. that may form said extended cell, for example by providing certain information together with information about SSB positions in the sequence, e.g. sequence numbers. This may be done when a wireless device first connects to an operator’s network, e.g. the wireless communication network 200, or when in active mode, when the wireless device enters a certain, e.g. given, area.

In case a wireless device receives both a SSB of a changing radio beam and of a static radio beam, it may be prioritized to use RACH resources associated with the SSB of the static radio beam, and the wireless device may even be restrained from accessing the RACH resources of the changing radio beams.

In order to assist wireless devices to save battery, the search for SSBs of changing radio beams may be restricted to certain frequencies. Since these SSBs, as explained above, may have long periodicity, a wireless device may need to be awake longer to be able to detect them, thus experiencing an effect of increased energy consumption, but if these SSBs are provided on and/or searched for on a sparser frequency grid compared to other SSBs, the effect can be reduced. For example, a search grid used by wireless devices may be limited to only a single frequency location per operator.

A wireless device may e.g. determine one or more search frequencies for SSBs of changing radio beams based on a coarse positioning. E.g. by first determining a country where the wireless device is located, e.g. by receiving a country code from another frequency band or by using a positioning mechanism such as GPS. The wireless device may then obtain country specific information on possible frequencies where SSBs of changing radio beams, such as with extended range, should be transmitted, if any. There may e.g. be a location-based table with potential frequencies of SSBs of changing, e.g. extended range, radio beams, which frequencies the wireless device can use and thereby only need to perform search over a small number of relevant frequencies with less energy consumption and less draining of battery than else would be the case.

Further, it may be advantageous if the SSBs of changing radio beams, e.g. with extended range, use different PSS and/or SSS and/or PBCH than the other SSBs, e.g. of static radio beams. This way it can be created two virtual cells where a second cell thus transmits SSBs of changing radio beams, e.g. with extended range, that extends another, first cell that e.g. corresponds to a“normal cell”, e.g. with coverage as illustrated in Figure 1. This means that embodiments herein may reduce impact on how wireless devices may have to change operation

Figure 5 is yet another block diagram schematically depicting transmission of radio beams with synchronization signals, in accordance with some embodiments herein. Figure 5 is supported by Figures 6a-b that schematically depicts two examples, respectively, of timing and frequency relations between SSBs comprised in radio beams as shown in Figure 5.

Figure 5 and 6a-b should at least partly be understood in view of the similarities with what already has been discussed above and shown for Figures 2a-b and 3-4, the following will therefore primarily focus on differences.

Figure 5 shows a radio network node 510, e.g. gNB, that transmits four different sets of radio beams. Each set comprise four radio beams comprising four SSBs, SSB0-SSB3, respectively. The SSBs are part of a SSB sequence that may correspond to a SS burst set. What is shown may thus correspond to a situation where L=4.

The radio network node 510 may correspond to the radio network node 210 or 310 and is comprised in a wireless communication network (not shown) that may be or correspond to the wireless communication network 200.

The figure illustrates that the radio network node 310 transmits a first set of radio beams 512a-d, transmits a second set of radio beams 513a-d, transmits a third set of radio beams 514a-d, and transmits a fourth set of radio beams 514a-d.

In Figure 5, all radio beams change coverage, i.e. change location between the sets, i.e. all beams here correspond to changed beams.

Further, as shown, there is a total area 518 covered by said sets of radio beams. Each of the fourth sets thus provide approximately 1/4 of the total area 518. In the figure it is also shown a comparison area 519 corresponding to an area that could be covered using the same transmit power if the radio beam of one set would be wider radio beams instead of being more narrow beams as shown and that has extended coverage compared to the wider beams. Such wider may correspond to such radio beams as shown in Figure 1 . Flence, the four set of radio beams here provide extended radio coverage and covers a total area 518 that is larger and includes an area, see said comparison area 519, that could be coved if only one or more sets with static radio beams would be used instead.

A wireless device 520, e.g. UE, that may correspond to the wireless device 220 or 320, and that may be in idle mode, is shown in the total area 518. The wireless device 320 is within the radio coverage provided by the fourth set of radio beams 515a-d, in particular by the radio beam thereof comprising SSB1 . The wireless device 520 will thus at least be able to receive synchronization signals through SSB1 and thereby be able to connect to the wireless communication network that radio network node 510 is part of. The wireless device 520 would not be able to do this in case if only static, wider radio beams instead would be used and cover only the comparison area 519.

The example of Figure 6a illustrates a situation where the radio beams of Figure 5 are separated in time, i.e. correspond to the situations discussed in the foregoing. Flere the four sets of radio beams are provided at time periods 662-665, respectively. It is also in Figure 6a exemplified a predetermined period 550, which predetermined period may correspond to the predetermined period 250 and 450, e.g. the 20 ms period, of previous examples and may thus be associated with a requirement of how often synchronization signals should be provided in an idle mode coverage area. Flere, however, the time periods between the sets of radio beams do not each correspond to the predetermined period 350, but they are all are comprised in the predetermined period 350, i.e. all radio beams of all the sets are transmitted within the predetermined period 650. The predetermined period 650 here correspond to a repeat period 670 determined by when a transmission sequence of the sets of radio beams is repeated. An advantage with this is that a wireless device, independent on where it is located within the total area, is able to receive a synchronization signal within the

predetermined period 650. In previous examples this has only been the case for wireless device located within coverage of static radio beams of the sets. On the other hand, the sequence of SSBs, e.g. SS burst sets, must then be provided more often, here 4 times as often as in the example of Figures 3 and 4, which also may result in higher energy consumption. The SSBs of the sequence, e.g. SS burst set, may here thus be transmitted more often than a wireless device, e.g. the wireless device 520, are able to detect them all, although they are transmitted in different subareas of the total area 518.

In these embodiments, the SSBs of different radio sets may carry different PSS and/or SSS and/or PBCH, thereby creating a hyper cell that consists of several cells each covering parts of the hyper cells total coverage area that correspond to the total area 518 and is larger than a conventional coverage corresponding to the comparison area 519.

The example of Figure 6b illustrates a situation where the radio beams of Figure 5 instead are separated in frequency, or rather both in time and frequency. Flere the four sets of radio beams are provided at the predetermined period 650, still e.g. 20 ms, but at different frequencies, i.e. separated in frequency, but may all be within a bandwidth 680 that thus may be 4 times a bandwidth for providing the sets of radio beams as illustrated in Figure 6a. The predetermined period 650 also here

corresponds to the repeat period 670. In this case, the sequence of SSBs, e.g. SS burst sets, ned not be provided more often than in the example of Figures 3 and 4, but the energy consumption would be higher due to that the sets of radio beams are transmitted at four frequencies during the predetermined period 650, typically at the same time, which would require also higher transmit power.

The sets of radio beams may correspond to, or be provided as cells,

respectively. For example, the first set of radio beams 512a-d may correspond to a first cell 1 , the second set of radio beams 513a-d may correspond to a second cell 2, the third set of radio beams 514a-d may correspond to a third cell 3 and the fourth set of radio beams 515a-d may correspond to a fourth cell 4. Said bandwidth 680 may then correspond to total, e.g. overlapping, system bandwidth of said cells 1 -4.

Figure 7 is a flowchart schematically illustrating embodiments of a method based on what has been discussed above. The method is for providing

synchronization signals of a wireless communication network, e.g. the wireless communication network 200. The wireless communication network may thus be a 5G and/or NR wireless communication network, such as defined by 3GPP. The method may be performed by one or more nodes, e.g. any one of the radio network nodes 210, 310, 510, the further node 230 or the further network 240, e.g. a computer cloud and then at least partly be provide as a service of the computer cloud.

The method comprises the following actions, which actions may be taken in any suitable order and/or be carried out fully or partly overlapping in time when this is possible and suitable.

Action 701

It is initiated transmission, e.g. by said one or more nodes, of a first set of radio beams, e.g. any one of the first sets 212a-b, 312a-d, 512a-d. When the one or more nodes is any of said radio network nodes, the one or more nodes may transmit, which includes initiation, in the present action. The transmission and initiation thereof may in that case be triggered by receiving some triggering information, e.g. an instruction, from another node, e.g. the further node 230 and/or the further network 240, and/or it may result from the radio network node is configured, e.g. programmed, to perform transmission based on occurrence of a certain event, e.g. at a certain time. When the one or more nodes is another node than the node actually making the transmission, the initiation of transmission in the present action may be that the one or more nodes sends said triggering information to one or more radio network node performing the actual transmission. The one or more nodes may in that case be configured, e.g.

programmed, to perform the initiation based on occurrence of a certain event, e.g. at a certain time.

The first set comprises SSBs, respectively, for enabling a wireless device, e.g. any one of the wireless devices 220, 320, 520, receiving such SSB to establish connection with the wireless communication network. Said SSBs of the first set belong to a certain sequence of SSBs and are thereby associated with SSB sequence numbers, respectively.

Said certain sequence of SSBs refers to a sequence of sequentially occurring SSBs and may correspond SSBs of a so-called SS burst set as discussed herein, which may comprise at most a certain number, e.g. L, of sequentially occurring SSBs, where L may be predefined and e.g. frequency dependent. Said certain sequence may thus be predefined and/or predetermined, and limited in length, i.e. there may be only a certain limited number of SSBs in the sequence and thus only a limited number of SSBs that are available and can be used during the length of a SS burst, i.e. during a certain time interval. Further, as should be understood, the sequence number that a SSB of the sequence is associated with, corresponds to an order of occurrence of the SSB in the sequence.

As used herein, a SSB, i.e. a synchronization signal block, corresponds to data structured in a predetermined way, e.g. according to a modulation format used, and that comprises one or more synchronization signals, and may be SSB corresponding to SSB as described above, e.g. comprising a PSS and/or SSS and/or PBCH. Further, the SSB may e.g. comprise or consist of one or more consecutive OFDM symbols, such as 4 consecutive OFDM symbols.

Action 702

It is initiated transmission, e.g. by said one or more nodes, of a second set of radio beams, e.g. any one of the second sets 212a-b, 312a-d, 512a-d. Said second set of radio beams comprise SSBs, respectively, that also belong to said certain sequence of SSBs. The second set comprises at least one changed radio beam, e.g. the radio beam 213b, the radio beam 313d or the radio beams 513a-d. Said at least one changed radio beam comprises a SSB associated with the same sequence number as a SSB of a radio beam of the first set, e.g. the radio beam 212b, the radio beam 312b or the radio beams 512a-d. However, the radio beam comprising this SSB is in the second set covering another area compared to the radio beam comprising this SSB in the first set. Thereby, a total area, e.g. any one of the total areas 218, 318 and 518, covered by the first set and second set in combination becomes larger than covered by each set alone.

In the context above it should be understood that by“the radio beam covering another area” means that the radio beam is provided to, i.e. is provided on purpose, to cover said another area, i.e. that is has and is provided to have a different coverage area.

Conventionally, a synchronization signal and e.g. a SSB with the same sequence number as in a preceding SS burst, would be retransmitted in a beam with the same coverage. However, with the method above and Actions 701 -701 according to embodiments herein, the at least one changed beam means that one or more SSBs with the same sequence number are transmitted in different areas, enabling a larger total area to be covered than possible by one set of radio beams carrying the SSBs, but without necessarily having to transmit with higher power or higher energy consumption. A wireless device that else could not be reached, can be reached by changed radio beams. Embodiments herein thereby e.g. enable idle mode coverage in NR to be extended to become closer to that of the connected mode, thus reducing a mismatch that else typically would occur. Such mismatch may else e.g. cause a UE experiencing dropped calls and connections to be unable to reconnect to the network due to lack of idle mode coverage and thus lack of synchronization signals.

In general, use of certain radio beams that change coverage as in embodiments herein increase flexibility and versatility for how synchronization signal can be provided. This for example also includes situations where e.g. the number of SSBs that can be used in a certain time interval is limited, e.g. due to that the sequence is limited, such as owing to a limited number of SSBs of a SS burst set when the wireless communication network is or is based on 5G or NR.

Further advantages from embodiment herein e.g. include:

additional interference caused by transmission of NR-SS to achieve extended coverage can be kept low, and it is enabled to reduce the time required to be able to use narrow connected mode radio beams.

Embodiments herein thus enable improved provision of synchronization signals.

In some embodiments, SSBs associated with certain one or more sequence numbers of the sequence are predefined to be used by radio beams that change coverage between the sets. An advantage with this is that it facilitates provision of changed radio beams and keeps apart radio beams and SSBs associated with changed radio beams from other radio beams and SSBs that may be provided in a more conventional manner. For example, if a SS burst set at most comprises a sequence of L SSBs, there may be predefined or predetermined that an absolute or relative number of these, e.g. a certain last part of the sequence, are to be used by radio beams that change coverage between the sets.

Further, in some embodiments, said second set is transmitted a certain time period, e.g. any one of the time periods 262, 462 and 662, after the first set, which time period is equal to or shorter than a predetermined period, e.g. any one of the predetermined periods 250, 450 and 650, associated with a requirement to provide a SSB in an area served by the wireless communication network. The predetermined period may be determined by or based on a periodicity of the SS burst set, and e.g. be 20 ms, such as when the wireless communication network is an NR based, such as a 5G, network. As mentioned above and in the Background, a main idea behind synchronization signals as provided by the SSBs is that they should be“always on”, such as always being transmitted, but which in practice means that they at least are very often retransmitted. Flow often may be related to said predetermined period, which may correspond to how often synchronization signals at least are and/or should be provided by the wireless communication network. The predetermined period may e.g. be explicitly or implicitly specified in a standard specification, whereby wireless devices for receiving SSBs can be configured to expect a SSB and synchronization signal to occur at least once within the predetermined period. Changed beam(s) of the second set that are transmitted shorter than the predetermined period after the first set, enables synchronization signals in the total area to occur at least once within the predetermined period, or at least more often than else would be the case, since each set alone does not cover the full total area. This is e.g. the case in Figure 6a.

Said at least one changed radio beam, e.g. any one of the radio beams 213b, 313d and 513a-d, may cover said another area by being transmitted in another direction in the second set compared to in the first set. Radio beams with SSB(s) having sequence numbers of said at least one changed radio beam may e.g. be “swept” over the sets, such as being formed and/or shaped the in the same way but directed differently in each set, such as offset with a certain angle in each set compared to the preceding set. Each set may e.g. be associated with a certain direction and/or coverage of a certain sector and/or angular range, for example so that the sets in combination provide a continuous coverage and the changed beams during a sequence of sets may thus“sweep” over the sector. This was e.g. discussed above in relation to Figure 3.

In some embodiments, said at least said at least one changed radio beam, e.g. any one of the radio beams 213b, 313d and 513a-d, is transmitted at other frequencies in the second set compared to in the first set. This e.g. enable simultaneous provision of the first set and the second set, e.g. if the first set is provided at frequencies different than the second set, and/or simultaneous provision of at least the changed radio beams of the sets, e.g. if at least the changed radio beams are at different frequencies. Sets, and/or radio beams, transmitted at different frequencies may belong to the same cell or different cells, e.g. such virtual cells or cells of a hypercell as discussed above. See e.g. what was described above in relation to Figure 6b.

Flowever, the sets of radio beams discussed for embodiments herein may belong to the same cell. They may be transmitted at same frequencies but with different coverage of the cell. Using different frequencies results in that the repeat period can be smaller but may require higher transmit power in total, e.g. in order to provide simultaneous transmission at multiple frequencies.

The radio beams, e.g. the radio beams 212b, 213b, 312d, 313d, 512a-d and 513a-d, comprising SSBs associated with sequence numbers of said least one changed radio beam, e.g. the radio beams 213b, 313d, 512a-d and 513a-d, are preferably narrower radio beams with longer range, i.e. have extended coverage, compared to other radio beams of the sets. The narrower beams may thus reach longer compared to the other radio beams that may be wider beams with shorter range, e.g. corresponding to more conventional radio beams providing SSBs. This way a wireless device, such as discussed in the Background, that conventionally would be outside an idle-mode coverage area and not able to access a cell even although the cell could still serve it, can be reached and be enabled to access the cell and thereby the wireless communication network.

The first set of radio beams, e.g. any one of the first sets of radio beams 212a-b, 312a-d and 512a-d, and the second set of radio beams, e.g. any one of the second sets of radio beams 213a-b, 313a-d and 513a-d, may comprise static radio beams, e.g. the radio beams 212a, 213a, 312a-c and 313a-c, that are radio beams having corresponding coverage areas in both sets. In this context corresponding coverage areas refers to that the coverage areas do not change, i.e. are static or the same, or substantially the same, between the sets. The static radio beams are thus other radio beams than said at least one changed radio beam and radio beams with SSBs associated with sequence number(s) of such changed radio beam(s) The static radio beams may correspond to said narrower radio beams with longer range. An advantage with these static radio beams is that they may correspond to and be used as conventional radio beams providing SSBs. The static radio beams may thus e.g. fulfil requirements as conventionally, such as providing SSBs within said predetermined period associated with a requirement to provide a SSB in an area, while radio beams with SSBs associated with sequence number(s) of changed radio beam(s) can be used to provide synchronization signals in addition to this, e.g. with improved coverage. This facilitate implementation and compatibility of embodiments herein with existing solutions.

In some embodiments, SSBs associated with sequence numbers of said least one changed radio beam, e.g. radio beams 213b, 313d, 512a-d and 513a-d, are associated with different PSS and/or SSS and/or PBCH than SSBs associated with other sequence numbers. The other sequence numbers may thus be of SSBs comprised in radio beams that do not change coverage between the sets. This way two virtual cells can be created, where one cell transmits SSB of changed radio beams, e.g. extended-range beams. A wireless device need not to be aware of the different cell types but the network can know which type of cell the wireless device connects to. An advantage is thus that wireless devices may need no special adaptation in this case, which facilitate implementation.

Action 703

It may further be initiated transmission, e.g. by said one or more nodes, of further one or more sets of radio beams, e.g. of one or more of the third sets 314a-d, 514a-d, the fourth sets 315a-d, 515a-d, fifth set 316a-d and sixth set 317a-d. These further one or more sets also comprise SSBs, respectively, that belong to said certain sequence of SSBs as the first and second sets. Any one of the further one or more sets may also comprise at least one changed radio beam, e.g. the radio beam 314d, the radio beam or the radio beams 514a-d. Said at least one changed radio beam of the further one or more sets may also comprises a SSB associated with the same sequence number as the SSB of the changed radio beam of the second set.

Action 704

It may then be initiated repeated transmission, e.g. by said one or more nodes, of Actions 701 -702 or Actions 701 -703, thereby accomplishing repeated transmission of a sequence with the sets of radio beams. In other words, said one or more nodes may initiate repeated transmission of a transmission sequence comprising the first set of radio beams, e.g. any one of the first sets with radio beams 212a-b, 312a-d and 512a-d, and the second set of radio beams, e.g. of the second sets with radio beams 213a-b, 313a-d and 513a-d. Thereby at least one SSB is receivable at any location within said total area, e.g. in any one of the total areas 218, 318 and 518, under a repeat period, e.g. any one of the repeat periods 270, 470 and 670, that is given by the repetition of the transmission sequence. Hence, the repeat period determines the time for the total area to be provided with synchronization signals through SSBs although there may be parts of the total area that are provided with SSBs more frequently by radio beams that do not change between the sets, such as said static radio beams.

The repeat period also determines when there will be a subsequent provision of SSBs of changed beams in certain subareas of the total area, e.g. next time a changed beam will have the same coverage as in the first set and thereby provide a SSB next within this coverage. A wireless device to receive SSBs and located at any location in the total area can thus expect to receive at least one SSB under the repeat period. The repeat period may be equal to or longer than said predetermined period. In case of longer, such as in Figures 2b and 4, there should be some radio beams in the sets that are not changed, i.e. are static beams, so that there will be at least some subarea in the total area where one or more SSBs are provided within the predetermined period.

Transmission in the method discussed above in relation to Figure 7 is

advantageously accomplished by means of beamforming, i.e. at least some of the radio beams are provided by beamforming, typically at least for transmission of said at least one radio beam that change between the sets.

Figure 8 is a schematic block diagram for illustrating embodiments of said one or more nodes, e.g. any one of the radio network nodes 210, 310, 510, the further node 230 or the further network 240, for providing synchronization signals of said wireless communication network, e.g. the wireless communication network 200.

The figure is particularly for illustrating how said one or more nodes may be configured to perform the method and actions discussed above in connection with Figure 7.

Said one or more nodes may comprise a processing module 801 , such as a means, one or more hardware modules, including e.g. one or more processors, and/or one or more software modules for performing said methods and/or actions.

Said one or more nodes may further comprise a memory 802 that may comprise, such as contain or store, a computer program 803. The computer program 803 comprises 'instructions' or 'code' directly or indirectly executable by Said one or more nodes so that they perform said method and/or actions. The memory 802 may comprise one or more memory units and may be further be arranged to store data, such as configurations and/or applications involved in or for performing functions and actions of embodiments herein.

Moreover, said one or more nodes may comprise a processing circuit 804 as an exemplifying hardware module and may comprise or correspond to one or more processors. In some embodiments, the processing module 801 may comprise, e.g. 'is embodied in the form of or 'realized by' the processing circuit 804. In these

embodiments, the memory 802 may comprise the computer program 803 executable by the processing circuit 804, whereby said one or more nodes are operative, or configured, to perform said method and/or actions. Typically, said one or more nodes, e.g. the processing module 801 , comprises an Input/Output (I/O) module 805, configured to be involved in, e.g. by performing, any communication to and/or from other units and/or nodes. The I/O module 805 may be exemplified by an obtaining, e.g. receiving, module and/or a providing, e.g. sending or transmitting, module, when applicable.

In further embodiments, said one or more nodes, e.g. the processing module 801 , may comprise an initiating module 806 as exemplifying hardware and/or software module(s).

In some embodiments, the initiating module 806 may be fully or partly implemented by the processing circuit 804.

Therefore, according to the various embodiments described above, said one or more nodes and/or the processing module 801 and/or the processing circuit 804 and/or the initiating module 806 and/or the I/O module 805, are operative, or configured, to initiate said transmission, and/or to transmit, said first set of radio beams.

Moreover, said one or more nodes and/or the processing module 801 and/or the processing circuit 804 and/or the initiating module 806 and/or the I/O module 805, are operative, or configured, to initiate said transmission, and/or to transmit, said second set of radio beams.

Further, in some embodiments, said one or more nodes and/or the processing module 801 and/or the processing circuit 804 and/or the initiating module 806 and/or the I/O module 805, are operative, or configured, to initiate said repeated transmission of the transmission sequence.

Figure 9 is a schematic drawing illustrating some embodiments relating to computer program(s) and carriers thereof to cause said one or more nodes discussed above in relation to Figures 7- 8, to perform the method actions. The computer program may be the computer program 803 and comprises instructions that when executed by the processing circuit 804 and/or the processing module 801 causes said one or more nodes to perform as described above. In some embodiments there is provided a carrier, or more specifically a data carrier, e.g. a computer program product, comprising the computer program 803. The carrier may be one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium, e.g. a computer readable storage medium 901 as schematically illustrated in the figure. The computer program 803 may thus be stored on the computer readable medium 901. By carrier may be excluded a transitory, propagating signal and the data carrier may correspondingly be named non-transitory data carrier. Non-limiting examples of the data carrier being a computer readable storage medium is a memory card or a memory stick, a disc storage medium such as a CD or DVD, or a mass storage device that typically is based on hard drive(s) or Solid State Drive(s) (SSD). The computer readable storage medium 901 may be used for storing data accessible over a computer network 902, e.g. the Internet or a Local Area Network (LAN). The computer program 803 may furthermore be provided as a pure computer program or comprised in a file or files. The file or files may be stored on the computer readable storage medium 901 and e.g. available through download e.g. over the computer network 902 as indicated in the figure, e.g. via a server. The server may e.g. be a web or File Transfer Protocol (FTP) server. The file or files may e.g. be executable files for direct or indirect download to and execution on said one or more nodes to make said one or more nodes to perform as described above, e.g. by execution by the processing circuit 804. The file or files may also or alternatively be for intermediate download and compilation involving the same or another processor to make them executable before further download and execution causing said one or more nodes to perform as described above.

Note that any processing module(s) mentioned in the foregoing may be implemented as a software and/or hardware module, e.g. in existing hardware and/or as an Application Specific Integrated Circuit (ASIC), a field-programmable gate array (FPGA) or the like. Also note that any hardware module(s) and/or circuit(s) mentioned in the foregoing may e.g. be included in a single ASIC or FPGA, or be distributed among several separate hardware components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

Those skilled in the art will also appreciate that the modules and circuitry discussed herein may refer to a combination of hardware modules, software modules, analogue and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in memory, that, when executed by the one or more processors may make the management node 130 to be configured to and/or to perform the above-described method. Identification by any identifier herein may be implicit or explicit. The identification may be unique in a certain context, e.g. in the wireless communication network or at least in a relevant part or area thereof.

The term "network node" or simply“node” as used herein may as such refer to any type of node that may communicate with another node in and be comprised in a communication network, e.g. the wireless communication network 200 or the further network 240. Further, such node may be or be comprised in a radio network node (described below) or any network node, which e.g. may communicate with a radio network node. Examples of such network nodes include any radio network node, a core network node, Operations & Maintenance (O&M), Operations Support Systems (OSS), Self Organizing Network (SON) node, etc.

The term "radio network node" as may be used herein may as such refer to any type of network node for serving a wireless device, e.g. a so called User Equipment or UE, and/or that are connected to other network node(s) or network element(s) or any radio node from which a wireless device receives signals from. Examples of radio network nodes are Node B, Base Station (BS), Multi-Standard Radio (MSR) node such as MSR BS, eNB, eNodeB, gNB, network controller, RNC, Base Station Controller (BSC), relay, donor node controlling relay, Base Transceiver Station (BTS), Access Point (AP), New Radio (NR) node, transmission point, transmission node, node in distributed antenna system (DAS) etc.

Each of the terms "wireless device", "user equipment" and "UE", as may be used herein, may as such refer to any type of wireless device arranged to communicate with a radio network node in a wireless, cellular and/or mobile communication system, and may thus be referred to as a wireless communication device. Examples include: target devices, device to device UE, device for Machine Type of Communication (MTC), machine type UE or UE capable of machine to machine (M2M) communication, Personal Digital Assistant (PDA), iPAD, Tablet, mobile, terminals, smart phone, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), Universal Serial Bus (USB) dongles etc.

While some terms are used frequently herein for convenience, or in the context of examples involving other a certain, e.g. 3GPP or other standard related, nomenclature, it must be appreciated that such term as such is non-limiting

Also note that although terminology used herein may be particularly associated with and/or exemplified by certain communication systems or networks, this should as such not be seen as limiting the scope of the embodiments herein to only such certain systems or networks etc.

As used herein, the term "memory" may refer to a data memory for storing digital information, typically a hard disk, a magnetic storage, medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like.

Furthermore, the memory may be an internal register memory of a processor.

Also note that any enumerating terminology such as first node, second node, first base station, second base station, etc., should as such be considered non-limiting and the terminology as such does not imply a certain hierarchical relation. Without any explicit information in the contrary, naming by enumeration should be considered merely a way of accomplishing different names.

As used herein, the expression "configured to" may mean that a processing circuit is configured to, or adapted to, by means of software or hardware configuration, perform one or more of the actions described herein.

As used herein, the terms "number" or "value" may refer to any kind of digit, such as binary, real, imaginary or rational number or the like. Moreover, "number" or "value" may be one or more characters, such as a letter or a string of letters. Also, "number" or "value" may be represented by a bit string.

As used herein, the expression“may” and "in some embodiments" has typically been used to indicate that the features described may be combined with any other embodiment disclosed herein.

In the drawings, features that may be present in only some embodiments are typically drawn using dotted or dashed lines.

As used herein, the expression "transmit" and "send" are typically

interchangeable. These expressions may include transmission by broadcasting, uni casting, group-casting and the like. In this context, a transmission by broadcasting may be received and decoded by any authorized device within range. In case of uni casting, one specifically addressed device may receive and encode the transmission.

In case of group-casting, e.g. multicasting, a group of specifically addressed devices may receive and decode the transmission.

When using the word "comprise" or "comprising" it shall be interpreted as nonlimiting, i.e. meaning "consist at least of".

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the present disclosure, which is defined by the appending claims.

Claims

1 . A method, performed by one or more nodes (210; 230; 240; 310; 510), for providing synchronization signals of a wireless communication network (200), wherein the method comprises:

- initiating transmission (701 ) of a first set of radio beams (212a-b; 312a-d; 512a- d) comprising Synchronization Signal Blocks,“SSBs”, respectively, for enabling a wireless device (220; 320; 520) receiving such SSB to establish connection with the wireless communication network (200), said SSBs of the first set belonging to a certain sequence of SSBs and are thereby associated with SSB sequence numbers, respectively, and

- initiating transmission (702) of a second set of radio beams (213a-b; 313a-d; 513a-d) comprising SSBs, respectively, also belonging to said certain sequence of SSBs, wherein the second set comprises at least one changed radio beam (213b; 313d; 513a-d) comprising a SSB associated with the same sequence number as a SSB of a radio beam (212b; 312d; 512a-d) of the first set but covering another area, whereby a total area (218; 318; 518) covered by the first set and second set in combination becomes larger than covered by each set alone.

2. The method as claimed in claim 1 , wherein SSBs associated with certain one or more sequence numbers of the sequence are predefined to be used by radio beams that change coverage between the sets.

3. The method as claimed in any one of claims 1 -2, wherein said second set is transmitted a certain time period (262; 462; 662) after the first set, which time period is equal to or shorter than a predetermined period (250; 450; 650) associated with a requirement to provide a SSB in an area served by the wireless communication network (200).

4. The method as claimed in any one of claims 1 -3, wherein the method further comprises:

- initiating repeated transmission (704) of a transmission sequence comprising the first set of radio beams (212a-b; 312a-d; 512a-d) and the second set of radio beams (213a-b; 313a-d; 513a-d), whereby at least one SSB is receivable at any location within said total area (218; 318; 518) under a repeat period (270;470; 670) given by the repetition of the transmission sequence.

5. The method as claimed in any one of claims 1 -4, wherein said at least one

changed radio beam (213b; 313d; 513a-d) covers said another area by being transmitted in another direction in the second set compared to in the first set.

6. The method as claimed in any one of claims 1 -5, wherein at least said at least one changed radio beam (213b; 313d; 513a-d) is transmitted at other frequencies in the second set compared to in the first set.

7. The method as claimed in any one of claims 1 -6, wherein radio beams (212b, 213b; 312d, 313d; 512a-d, 513a-d) comprising SSBs associated with sequence numbers of said least one changed radio beam (213b; 313d; 512a-d, 513a-d) are narrower radio beams with longer range compared to other radio beams of the sets.

8. The method as claimed in any one of claims 1 -7, wherein the first set of radio beams (212a-b; 312a-d; 512a-d) and the second set of radio beams (213a-b; 313a-d; 513a-d) comprise static radio beams (212a, 213a; 312a-c, 313a-c) that are radio beams having corresponding coverage areas in both sets.

9. The method as claimed in any one of claims 1 .8, wherein SSBs associated with sequence numbers of said least one changed radio beam (213b; 313d; 512a-d, 513a-d) are associated with different Primary Synchronization Signal,“PSS”, and/or Secondary Synchronization Signal,“SSS”, and/or Physical Broadcast Channel,“PBCH”, than SSBs associated with other sequence numbers.

10. A computer program (803) comprising instructions that when executed by a processing circuit (804) causes the node (210; 230; 240; 310; 510) to perform the method according to any one of claims 1 -9.

1 1 . A carrier comprising the computer program (803) according to claim 10, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium (901 ).

12. One or more nodes (210; 230; 240; 310; 510) for providing synchronization

signals of a wireless communication network (200), wherein said one or more nodes (210; 230; 240; 310; 510) are configured to:

initiate transmission (701 ) of a first set of radio beams (212a-b; 312a-d;

512a-d) comprising Synchronization Signal Blocks,“SSBs”, respectively, for enabling a wireless device (220; 320; 520) receiving such SSB to establish connection with the wireless communication network (200), said SSBs of the first set belonging to a certain sequence of SSBs and are thereby associated with SSB sequence numbers, respectively, and

initiate transmission (702) of a second set of radio beams (213a-b; 313a-d; 513a-d) comprising SSBs, respectively, also belonging to said certain sequence of SSBs, wherein the second set comprises at least one changed radio beam (213b; 313d; 513a-d) comprising a SSB associated with the same sequence number as a SSB of a radio beam (212b; 312d; 512a-d) of the first set but covering another area, whereby a total area (218; 318; 518) covered by the first set and second set in combination becomes larger than covered by each set alone.

13. The one or more nodes (210; 230; 240; 310; 510) as claimed in claim 12,

wherein SSBs associated with certain one or more sequence numbers of the sequence are predefined to be used by radio beams that change coverage between the sets.

14. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of

claims 12-13, wherein said second set is transmitted a certain time period (262; 462; 662) after the first set, which time period is equal to or shorter than a predetermined period (250; 450; 650) associated with a requirement to provide a SSB in an area served by the wireless communication network (200).

15. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-14, wherein said one or more nodes (210; 230; 240; 310; 510) are further configured to:

initiate repeated transmission (704) of a transmission sequence comprising the first set of radio beams (212a-b; 312a-d; 512a-d) and the second set of radio beams (213a-b; 313a-d; 513a-d), whereby at least one SSB is receivable at any location within said total area (218; 318; 518) under a repeat period (270;470; 670) given by the repetition of the transmission sequence.

16. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-15, wherein said at least one changed radio beam (213b; 313d; 513a- d) covers said another area by being transmitted in another direction in the second set compared to in the first set.

17. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-16, wherein at least said at least one changed radio beam (213b;

313d; 513a-d) is transmitted at other frequencies in the second set compared to in the first set.

18. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-17, wherein radio beams (212b, 213b; 312d, 313d; 512a-d, 513a-d) comprising SSBs associated with sequence numbers of said least one changed radio beam (213b; 313d; 512a-d, 513a-d) are narrower radio beams with longer range compared to other radio beams of the sets.

19. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-18, wherein the first set of radio beams (212a-b; 312a-d; 512a-d) and the second set of radio beams (213a-b; 313a-d; 513a-d) comprise static radio beams (212a, 213a; 312a-c, 313a-c) that are radio beams having corresponding coverage areas in both sets.

20. The one or more nodes (210; 230; 240; 310; 510) as claimed in any one of claims 12-19, wherein SSBs associated with sequence numbers of said least one changed radio beam (213b; 313d; 512a-d, 513a-d) are associated with different Primary Synchronization Signal,“PSS”, and/or Secondary

Synchronization Signal,“SSS”, and/or Physical Broadcast Channel,“PBCH”, than SSBs associated with other sequence numbers.