Patent Description:
Radio-based channel sensing may be considered as an emerging technology at least for cellular communication networks. Possible use cases of radio-based sensing comprise, for example, intruder detection (home, railway, highway), rainfall monitoring, sensing assisted transportation (maneuvering and navigation, cross-roads clearance), management of unmanned aerial vehicles (trajectory tracing, collision avoidance), sleep monitoring, positioning and health monitoring. Sensing may be generally used to sense environment, comprising also static or other objects which might not be connected to a network, like passive objects. Radio-based sensing may be exploited in various cellular communication networks, such as, in cellular communication networks operating according to <NUM> radio access technology and/or future <NUM> radio access technology. <NUM> radio access technology may also be referred to as New Radio, NR, access technology. 3rd Generation Partnership Project, 3GPP, develops standards for <NUM>/NR. In general, there is a need to provide enhanced methods, apparatuses and computer programs for enhancing radio-based sensing in cellular communication networks. Such enhancements may also be beneficial in other wireless communication networks, such as in <NUM> networks in the future. <CIT> discloses techniques and apparatuses for remaining minimum system information (RMSI) physical downlink control channel (PDCCH) monitoring. A method for wireless communications by a user equipment (UE) is provided. During initial access of a cell, the UE determines a default first periodicity to monitor for at least a first PDCCH scheduling RMSI. After the initial access, the UE determines a second periodicity to monitor at least a second PDCCH scheduling RMSI based on the default first periodicity or based on an indication received in a previous RMSI from the cell. The UE monitors for at least the first PDCCH during initial access at the default first periodicity and monitors for at least the second PDCCH at the second periodicity after the initial access. <CIT> discloses a method and system for enabling a UE to determine whether the UE can skip the acquisition of SIB1-BR. An indication (e.g., a one bit flag) in the MIB is provided, which indication is set to a particular value if the UE needs to read SIB1-BR, otherwise the indication is set to a different value indicating that the UE can skip reading SIB1-BR assuming other conditions are met (e.g., assuming that the UE has previously read SIB1-BR within a MIB indication time period).

According to some aspects, there is provided the subject-matter of the independent claims. Some example embodiments are defined in the dependent claims.

To achieve the foregoing objective, the invention is as defined in the claims. The following aspects are provided for illustrative purposes.

According to a first aspect of the present disclosure, there is provided an apparatus comprising means for determining first information for reception of a synchronization signal block from a cell of a source wireless network node, means for determining second information for reception of at least one part of a system information block from the cell of the source wireless network node, wherein the second information is unchanged compared to at least one part of a previous system information block, means for determining third information for reception of a physical downlink control channel from the cell of the source wireless network node, wherein the third information is unchanged compared to a previous physical downlink channel, means for receiving the synchronization signal block and the system information block, means for receiving the physical downlink control channel, means for performing processing of the first information of the synchronization signal block and the second information of the at least one part of the system information block, and means for performing channel sensing based on the first information of the synchronisation signal block and the second information of the at least one part of the system information block and the third information of the physical downlink control channel. The apparatus of the third aspect may be a user equipment or observing wireless network node, or a control device configured to control the functioning thereof, possibly when installed therein.

According to a second aspect, there is provided a method comprising determining, by an apparatus, first information for reception of a synchronization signal block from a cell of a source wireless network node, determining, by the apparatus, second information for reception of at least one part of a system information block from the cell of the source wireless network node, wherein the second information is unchanged compared to at least one part of a previous system information block, determining, by the apparatus, third information for reception of a physical downlink control channel from the cell of the source wireless network node, wherein the third information is unchanged compared to a previous physical downlink channel, receiving, by the apparatus, the synchronization signal block and the system information block, receiving, by the apparatus, the physical downlink control channel, performing, by the apparatus, processing of the first information of the synchronization signal block and the second information of the at least one part of the system information block, and performing, by the apparatus, channel sensing based on the first information of the synchronisation signal block and the second information of the at least one part of the system information block and the third information of the physical downlink control channel. The method of the fifth aspect may be performed by a user equipment or observing wireless network node, or a control device configured to control the functioning thereof, possibly when installed therein.

According to a third aspect of the present disclosure, there is provided a computer program comprising instructions which, when the program is executed by an apparatus, cause the apparatus to carry out the method of the second aspect.

Sensing in cellular communication networks may be enhanced by the procedures described herein. More specifically, sensing in cellular communication networks may be enhanced by utilizing jointly transmissions of Synchronization Signal Blocks, SSBs, and System Information Block <NUM>, SIB1, for example for sensing a channel. A SIB1 may refer to higher layer signalling content while a Physical Downlink Shared Channel, PDSCH, may be the physical channel that carries the SIB1. A Physical Downlink Control Channel, PDCCH, may be used to schedule time and frequency resources for the PDSCH.

At least one part of a SIB1 may comprise information which is suitable for sensing, like unchanged information compared to a previous SIB1, such as a previously decoded SIB1. Hence, the SIB1 transmission may be exploited to provide wider bandwidth and longer time for sensing, and enhanced measurement time-granularity. Sensing performance, such as ranging accuracy and velocity estimation accuracy, may be therefore substantially improved without increasing radio interface overhead.

<FIG> illustrates an example of a network scenario in accordance with at least some example embodiments. According to the example scenario of <FIG>, there may be a cellular communication system, which comprises UE <NUM>, source wireless network node <NUM>, observing wireless network node <NUM> and core network element <NUM>. UE <NUM> may be connected to source wireless network node <NUM> via air interface <NUM>. Source wireless network node <NUM> may be considered as a serving node of UE <NUM> and one cell of wireless network node <NUM> may be a serving cell of UE <NUM>.

In some example embodiments, air interface <NUM> may be a beam-based air interface. UE <NUM> and observing wireless network node <NUM> may receive and measure signals transmitted by source wireless network node <NUM> over air interface <NUM>. Hence, UE <NUM> and observing wireless network node <NUM> may perform channel sensing based on signal transmitted by source wireless network node <NUM> over air interface <NUM>. In case of Joint Communication and Sensing, JCAS, source wireless network node <NUM> may perform sensing. For example, source wireless network node <NUM> may perform sensing, like mono-static sensing, in addition to bi-static sensing by observing wireless network node <NUM> or UE <NUM>.

In some example embodiments, a mono-static radar may allow for sensing with one wireless network node, but not more than one, where a receiver and a transmitter may be co-located and the mono-static radar may exploit an entire transmitted grid known to the receiver. In a bi-static or a multi-static case, a transmitter and a receiver may be separately placed in several nodes and the receiving nodes may have prior knowledge of the transmitted signal, meaning that sensing enablers may be common reference signals or additional synchronization signaling between all wireless network nodes. Signal processing related to sensing may be, e.g., correlation based signal detection to obtain range and/or velocity relationship for the reflected signals. So also the delay and Doppler shift of the received signal reflection may be estimated for the range and velocity, and potentially an angle of arrival as well.

Thus, transmitted and received in-phase and quadrature samples may be used for channel sensing in addition to the received power. The fundamental aspects of channel sensing may be delay estimation and Doppler estimation, which map to target/object distance and velocity. Depending on more specific arrangements related to an antenna system, target direction may be estimated, which together with distance maps already to a target position. Channel sensing might be also referred to as sensing, radio-based sensing or object sensing.

UE <NUM> may comprise, for example, a smartphone, a cellular phone, a Machine-to-Machine, M2M, node, Machine-Type Communications, MTC, node, an Internet of Things, IoT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, any kind of suitable wireless terminal. Air interface <NUM> between UE <NUM> and wireless network nodes <NUM>, <NUM> may be configured in accordance with a Radio Access Technology, RAT, which both UE <NUM> and wireless network nodes <NUM>, <NUM> are configured to support. Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which may also be known as fifth generation, <NUM>, radio access technology, <NUM>, and MulteFire. For instance, UE <NUM> and wireless network nodes <NUM>, <NUM> may be configured to operate according to at least one 3rd Generation Partnership Project, 3GPP, standard.

For example in the context of LTE, wireless network nodes <NUM> and <NUM> may be referred to as eNBs while wireless network nodes: source wireless network node <NUM>, and observing wireless node <NUM> may be referred to as gNBs in the context of NR. Wireless network nodes <NUM> and <NUM> may, in general, be referred to as base stations, base station nodes or radio access nodes. In some example embodiments, wireless network nodes <NUM> and <NUM> may comprise entities like a gNB-Distributed Unit, DU, and gNB-Centralized Unit, CU. The gNB-DU and the g-NB-CU may be connected by an interface such as F1.

In some example embodiments, wireless network nodes <NUM> and <NUM> may be referred to as Transmission and Reception Points, TRPs, or control multiple TRPs that may be co-located or non-co-located. In any case, example embodiments of the present disclosure are not restricted to any particular wireless technology. Instead, example embodiments may be exploited in any wireless communication system, wherein channel sensing may be performed based on SSBs and SIB1s.

Wireless network nodes <NUM> and <NUM> may be connected, directly or via at least one intermediate node, with core network <NUM> via interface <NUM>. Core network <NUM> may be, in turn, coupled via interface <NUM> with another network (not shown in <FIG>), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network. Wireless network nodes <NUM> and <NUM> may be connected with each other directly via inter-BS interface <NUM>, e.g., using an Xn interface or an X2 interface. In some example embodiments, direct inter-BS interface <NUM> may be absent though. In such a case, wireless network nodes <NUM> and <NUM> may communicate with each other via interface <NUM> and core network <NUM>.

In some example embodiments, the network scenario may comprise a relay node instead of, or in addition to, at least one of UE <NUM>, source wireless network node <NUM> and observing wireless network node <NUM>. Relaying may be used for example when operating on millimeter-wave frequencies. One example of the relay node may be an Integrated Access and Backhaul, IAB, node. The IAB node may be referred to as a self-backhauling relay as well. Another example of a relay may be an out-band relay. For instance, the relay node may comprise two parts:.

Integrated sensing and communications functionalities may be exploited in various wireless communication networks, such as in cellular communication networks, like <NUM>/NR networks. In addition, integrated sensing and communications functionalities may be exploited at least in upcoming <NUM> networks. At least some use cases may require bi-static sensing operation, where source wireless network node <NUM> may act as a transmitter and UE <NUM> may act as a receiver, and potentially observing wireless network node <NUM> as well. To support this kind of bi-static sensing operation, frequent and wide bandwidth transmissions of known reference signals may be required for accurate and low-latency sensing operation.

The use of such reference signals would increase the system overhead and reduce the communications capacity though. In addition, considering the ever-tightening requirements for energy-efficiency, the introduction of additional reference signals would have a negative influence on the energy budget. Thus, it would be beneficial to bring sensing capability for example to <NUM>-Advanced without introducing additional reference signals. In some example embodiments of the present disclosure, existing signals may be therefore utilized for channel sensing, to make best use of the system for both sensing and communications.

Regarding the overhead and energy issues, sensing-related reference signals may introduce a larger negative impact compared to, for example, positioning-related reference signals. This is because, in many sensing-related use cases, like in case of home intruder detection, it would be beneficial if the sensing functionality would work in always-on principle to enable continuous monitoring and sensing of the environment. On the other hand, a positioning service may be needed only during an active operation of UE <NUM>.

In cellular communication networks, synchronization signals and common broadcast channels, such as Primary Synchronization Signal, PSS, Secondary Synchronization Signal, SSS, and Physical Broadcast Channel, PBCH, in <NUM> NR, may be repeatedly transmitted which is generally good for sensing. However, said synchronization signals and common broadcast channels may lack in sensing performance due to limited bandwidth, which would further limit the range estimation capabilities. Also, said synchronization signals and common broadcast channels may lack in sensing performance due to limited duration, which would further limit the velocity estimation capabilities. Thus, in some example embodiments, the use of said synchronization signals and common broadcast channels may be enhanced for channel sensing. More specifically, the use of said synchronization signals and common broadcast channels for channel sensing may be incorporated with the use of SIB1 transmission framework, to enable enhanced sensing capabilities.

Some example embodiments may be applied to enable, e.g., improved sensing performance for a mono/bi-static downlink-signal-based sensing. For instance, joint utilization of SSBs, and semi-persistent downlink transmission of SIB1 transmitted on a PDSCH and associated PDCCH information (Type#<NUM>-PDCCH information), also referred to as Control Resource Set #<NUM>, CORESET#<NUM>, may be enabled efficiently. In some example embodiments, said associated PDCCH information may also be referred to as a downlink assignment or Downlink Control Information, DCI. CORESET#<NUM> may refer to Type#<NUM>-PDCCH on CORESET#<NUM> resources although also other PDCCHs may be transmitted on the CORESET#<NUM>.

In some example embodiments, each of the SSB and SIB1 may have a predetermined transmission periodicity, defined in a 3GPP standard for example, to ensure continuous sensing availability. For instance, transmission periodicity may be defined as <NUM>-<NUM> for the SSB and <NUM> for the SIB1/CORESET#<NUM>. For cell search, the SSB periodicity assumed by UE <NUM> may be <NUM>, e.g., in <NUM>/NR networks. In some example embodiments, it may be defined in a 3GPP standard that SSBs need to be transmitted by source wireless network node <NUM> with a given periodicity. However, source wireless network node <NUM> may be allowed to decide how to deal with PDCCH for CORESET#<NUM> and SIB1. For example, source wireless network node <NUM> may decide whether or not to transmit PDCCH for CORESET#<NUM> and SIB1. PDCCH for CORESET#<NUM> may correspond to Type#<NUM>-PDCCH and used to schedule SIB1 (transmitted via PDSCH) In any case, the transmission interval should be enough frequent though, or otherwise, the initial access performance would be decreased, i.e., delayed.

Information for reception of a SSB may be referred to as first information and information for reception of at least one part of a SIB1 may be referred to as second information. The first information may comprise a content of the SSB and resources of the SSB. The second information may be unchanged compared to at least one part of a previous SIB1, like a previously decoded SIB1. That is, even though in some example embodiments a previously decoded SIB1 is used as an example, the example embodiments may be applied similarly when the second information is unchanged compared to at least one part of a previous SIB1.

The first information in SSBs, including PSS, SSS, and PBCH, may be considered static as a function of time, but the second information in SIB1 may vary over time. That is, the changes in the first information may be known if the timing of the cell is known. For instance, systemFrameNumber in a Master Information Block, MIB, may be known if the timing of the cell is known. However, in practice the SIB1, carrying for example mandatory information on random access, may remain constant for long times and change only infrequently. In some example embodiments of the present disclosure, sensing measurements based on SSB and SIB1 transmissions may be therefore obtained by not only the node transmitting SSBs and SIBs, like source wireless network node <NUM>, but also both receivers, UE <NUM> and observing wireless network node <NUM>.

In some example embodiments, a SIB1-optimized sensing framework may be provided. Possible changes in the SIB1 information, i.e., second information for channel sensing, may be handled for example as follows.

In some example embodiments, SIB1s may be assumed unchanged unless a change is separately indicated by source wireless network node <NUM>. For instance, the information in SIB1s, or at least a part of it, may be assumed unchanged compared to a previously decoded SIB1. For instance, source wireless network node <NUM> may transmit an indication to UE <NUM>, the indication indicating that information of SIB1 is changed. That is, the indication may indicate that the information, which has been unchanged compared to a previously decoded SIB1, has been changed now. In some example embodiments, multiple UEs may be informed separately, e.g., via a paging message. That is, UE <NUM> may receive the indication in a paging message. Other wireless network nodes may be informed via inter-BS interface <NUM>, e.g., using Xn-signaling, to support for a bi-static sensing scenario. For instance, source wireless network node <NUM> may transmit the indication to observing wireless network node <NUM> via inter-BS interface <NUM>.

UE <NUM> may use every SIB1 for sensing as long as they are unchanged, after the SIB1 has been decoded once. That is, UE <NUM> may use a received SIB1 for channel sensing if the received SIB1 is unchanged compared to a previously decoded SIB1. The received SIB1 may be a known signal, defined in a 3GPP standard for example. That is, one use case is to use PDCCH/SIB as always on known signal that may be used to improve channel estimation and/or frequency/time synchronization (similarly as a reference signal). In some example embodiments, source wireless network node <NUM> may configure the transmission periodicity according to channel sensing needs.

In some example embodiments, a SIB1 may be divided into two parts. A first part of the SIB1 may comprise unchanged information, compared to a first part of a previously decoded SIB1 for example, and a second part of the SIB1 may comprise variable information. The first part may thus comprise unchanged information that is feasible for channel sensing. Said information may be assumed practically as stable as the information in PBCH. Hence, the indication indicating the change may not be needed. If changes are needed, source wireless network node <NUM> may perform a system information update or a cell reset. The second part may comprise variable information that is not usable for channel sensing. The second part may be referred to as another part as well. In some example embodiments, there may be more than one second part, i.e., at least two other parts.

In some example embodiments, the first and the second parts of the SIB1 may be multiplexed, e.g., to maximize suitability for sensing. One potential reason may be to ensure that sensing part occupies high enough bandwidth, to increase range estimation accuracy accordingly For instance, the first part may be spread over a PDSCH bandwidth in a comb-like pattern. The PDSCH may be for transmission of the first and second parts of the SIB1.

In some example embodiments, SIB1s may be assumed unchanged for a predefined time period. That is, SIB1s may comprise unchanged information, compared to a previously decoded SIB1 for example, and said information may be assumed unchanged for the time period. UEs participating in sensing may be required to detect and decode a SIB1 at a beginning of each new time period. That is, for example UE <NUM> may determine that the time period has ended and after that, detect and decode the next SIB1. Other wireless network nodes may be informed via inter-BS interface <NUM>, e.g., using Xn-signaling. For instance, source wireless network node <NUM> may transmit an indication about the change to observing wireless network node <NUM> via inter-BS interface <NUM>. In some example embodiments, the SIB1 may comprise parameters for SIB1 transmission periodicity that source wireless network node <NUM> follows for the time period, as well as parameters, like period and time offset, defining the time period for the unchanged SIB1.

The SIB1 periodicity may be included in the SIB1 content to enable more dynamic adaptation, so that sensing may benefit from it compared to traditional system information signalling. For instance, the SIB1 may be transmitted more frequently than <NUM> to facilitate sensing. The periodicity of SIB1s may be adjustable, e.g., to adjust the trade-off between current needs for sensing and overhead caused by more frequent SIB1 transmissions, depending for example on the traffic load of the cell.

The at least one part of the SIB1, and potentially the associated PDCCH, may be defined to be always on and transmitted using a predefined content/resources/format. The predefined content/resources/format may be referred to as second information. The predefined content/resources/format for SIB1 may mean that the payload, time and frequency resources, coding, modulation, etc., are not changed. In the case of type#<NUM> PDCCH, the payload, aggregation level or CORESET#<NUM> resources used for type#<NUM> PDCCH might not be changed. UE <NUM> may obtain such information when it decodes SIB1 correctly. The payload, aggregation level or CORESET#<NUM> resources used for type#<NUM> PDCCH may be referred to as third information.

That is, predefined (if not all) SSB occasions may be defined to comprise both, the SIB1 and the associated PDCCH. Alternatively, the SIB1 with predefined information, like at least one content, resources and format, may be triggered by means of the associated PDCCH, even though said information of the SIB may still be predefined. In some example embodiments, UE <NUM> may assume that the predefined SIB1 is transmitted only if the associated PDCCH is received.

The presence of "always on SIB1" may be indicated by source wireless network node <NUM> by means of broadcast signaling. For example, the SIB1, some other predefined SIBx or MIB may be used to indicate that the associated cell of source wireless network node <NUM> follows procedures defined for "always on SIB1".

The example embodiments of the present disclosure may be applied similarly for any other SIB with similar functionality than SIB1. That is, even though SIB1 is used as an example in the example embodiments of the present disclosure, the example embodiments of the present disclosure are not specifically limited to SIB1. Instead, SIB1 may be replaced with any other SIB with similar functionality. In some example embodiments, a system information block, like SIB1 or some other SIB with similar functionality, may comprise cell-specific information of the cell of source wireless network node <NUM>. Alternatively, or in addition, a system information block, like SIB1 or some other SIB with similar functionality, may comprise Remaining Minimum System Information, RMSI.

<FIG> illustrates a first example in accordance with at least some embodiments. In <FIG>, SSB is denoted by <NUM>, CORESET#<NUM><NUM> and SIB1 <NUM>. SIB <NUM> may be carried on a PDSCH. In the first example illustrated in <FIG>, SIB1 <NUM> may comprise unchanged information <NUM> compared to a previously decoded SIB1.

<FIG> illustrates different exemplary multiplexing scenarios for SSB <NUM>, CORESET#<NUM><NUM> and SIB1 <NUM>. More specifically, <FIG> illustrates an example, wherein SSB <NUM> may be transmitted at a different time than SIB1 <NUM> comprising unchanged information <NUM>. <FIG> illustrates an example, wherein SSB <NUM> may be transmitted on a different frequency than SIB1 <NUM> but at the same time as SIB1 <NUM> comprising unchanged information <NUM>. <FIG> illustrates an example, wherein SSB <NUM> may be transmitted on a different frequency than CORESET#<NUM><NUM> and SIB1 <NUM> but at the same time as CORESET#<NUM><NUM> and SIB <NUM><NUM>.

<FIG> illustrates a second example in accordance with at least some embodiments. On the vertical axes are disposed, from the left to the right, UE <NUM>, source wireless network node <NUM> and observing wireless network node <NUM>. Time advances from the top towards the bottom.

In some example embodiments, in the beginning of the sensing procedure, UE <NUM> may indicate its interest on channel sensing, and the sensing session is set up. Such an indication may not be needed in all scenarios. Alternatively, UE <NUM> may indicate that it supports sensing based on a signal of a wireless network node or that it may leverage SIB <NUM> as a known signal.

Source wireless network node <NUM> may be configured to transmit SSBs, like SSB <NUM> illustrated in <FIG>, CORESET#<NUM> signals, like CORESET#<NUM><NUM> illustrated in <FIG>, and SIB1 signals, like SIB1 <NUM> illustrated in <FIG>. In some example embodiments, source wireless network node <NUM> may be referred to as a source gNB. In addition to UEs, other wireless network nodes, like observing wireless network node <NUM>, may be involved in the sensing process, either by observing and/or measuring the signals in the considered session or providing more measurement opportunities by additional SSB and SIB <NUM>/CORESET#<NUM> transmissions. In some example embodiments, source wireless network node <NUM> may be involved in the sensing process, e.g., in case of mono-static sensing.

At step <NUM>, channel sensing session may be started. For example, initialization, measurement setup and assistance data may be provided. Source wireless network node <NUM> may transmit a SSB and a SIB1. UE <NUM> may detect and decode the SSB and SIB1. UE <NUM> may determine, based on the decoded SSB and SIB1, information, i.e., content and arrangement, for sensing based on a SSB and at least one part of a SIB1, respectively. Observing wireless network node <NUM> may determine said information for reception of a SSB and for reception of at least one part of a SIB1 similarly for channel sensing. The decoded SIB1 may referred to as a previously decoded SIB1. After setting up the initial sensing session configurations, UE <NUM> and observing wireless network node may be able to use SSB and SIB <NUM>/CORESET#<NUM> transmissions for channel sensing purposes.

Sensing process may be ongoing at steps <NUM> and <NUM>. At step <NUM>, source wireless network node <NUM> may transmit a SSB and a SIB1 for sensing a channel. Similarly, at step <NUM>, source wireless network node <NUM> may transmit the SSB and the SIB1 again for sensing the channel Consequently, UE <NUM> and observing wireless network node <NUM> may receive the SSBs and the SIB1s. The transmissions, at steps <NUM> and <NUM>, may be beam sweeping transmission.

UE <NUM> and observing wireless network node <NUM> may further assume that said information of the at least one part of the SIB1 is unchanged. For instance, UE <NUM> and observing wireless network node <NUM> may assume that information in the received CORESET#<NUM>, like CORESET#<NUM><NUM> in <FIG>, and information in the received SIB1, like SIB <NUM><NUM> in <FIG>, are unchanged compared to the previously decoded CORESET#<NUM> and SIB1, like the CORESET#<NUM> and SIB1 transmitted at step <NUM>. The information in the received SIB1 may refer to a format and resources on which the SIB1 (and CORESET#<NUM>) are transmitted.

UE <NUM> and observing wireless network node <NUM> may then perform sensing with unchanged SIB1 information. That is, UE <NUM> and observing wireless network node <NUM> perform channel sensing based on said information of the SSB and said information of the at least one part of the SIB1. Said sensing may be performed using the SIB1 as a known reference signal. Alternatively, reception of the SIB1 may be skipped by UE <NUM> or at least channel decoding of the SIB1. In some example embodiments, "always on PBCH/SIB" with known content may be used as an additional reference signal, which may be available also for "other-than-sensing" purposes, for example for maintaining frequency/time synch without periodical tracking reference signal). That is, UE <NUM> and observing wireless network node <NUM> may perform processing of the first information of the SSB and the second information of the at least one part of the SIB1.

At step <NUM>, source wireless network node <NUM> may determine that there is a need to change said information in the SIB1. In the occasion of a change in SIB <NUM>/CORESET#<NUM>, source wireless network node <NUM> may trigger the change. For example, the change may be triggered if cell load changes considerably and there is a need for additional random access channel resources. Alternatively, or in addition, the change may be triggered due to reconfiguration of some parameters of a serving cell or source wireless network node <NUM> by an operator.

At step <NUM>, source wireless network node <NUM> may transmit an indication to UE <NUM>, the indication indicating that information for reception of SIB <NUM> is changed. The indication may be transmitted in a paging message, i.e., source wireless network node <NUM> may perform paging with indication on the change in the SIB <NUM>. Hence, UE <NUM> may be notified about the change in SIB <NUM>, for example, based on a paging message for an idle UE, or specific Radio Resource Control, RRC, signalling for an active UE.

At step <NUM>, source wireless network node <NUM> may transmit the indication to observing wireless network node <NUM>. For instance, if the SIB1 change occurs in a neighbouring wireless network node, i.e., not source wireless network node <NUM>, the change in SIB1 may be conveyed to UE <NUM>, for example, through an Xn-interface between the neighbouring wireless network node and source wireless network node <NUM>. In addition, observing wireless network node <NUM> may be indicated about the change in SIB1 using inter-BS interface <NUM>, e.g., using the Xn-interface.

At step <NUM>, source wireless network node <NUM> may transmit the SSB and the changed SIB1 for sensing a channel. The transmission, at step <NUM>, may be a beam sweeping transmission. At steps <NUM> and <NUM>, UE <NUM> and observing wireless network node <NUM>, may detect and decode the SSB and the changed SIB1. The SIB1, decoded at steps <NUM> and <NUM>, may become a previously decoded SIB1. Hence, UE <NUM> and observing wireless network node <NUM> may determine, based on the previously decoded SIB1, information for reception of a subsequent SSB and for reception of at least one part of a subsequent SIB1, for channel sensing.

Sensing process may be again ongoing at steps <NUM> and <NUM>. At step <NUM>, source wireless network node <NUM> may transmit the subsequent SSB and the subsequent SIB1 for sensing a channel. Similarly, at step <NUM>, source wireless network node <NUM> may transmit the subsequent SSB and the subsequent SIB1 again for sensing the channel Consequently, UE <NUM> and observing wireless network node <NUM> may receive the subsequent SSBs and the subsequent SIB1s. The transmissions, at steps <NUM> and <NUM>, may be beam sweeping transmission.

UE <NUM> and observing wireless network node <NUM> may further assume that information of the at least one part of the subsequent SIB1 is unchanged, compared to the SIB1 detected and decoded at steps <NUM> and <NUM>. For instance, UE <NUM> and observing wireless network node <NUM> may assume that information in the received CORESET#<NUM>, like CORESET#<NUM><NUM> in <FIG>, and information in the received SIB1, like SIB1 <NUM> in <FIG>, are unchanged compared to the previously decoded SIB1. UE <NUM> and observing wireless network node <NUM> may then perform sensing with unchanged SIB1 information. That is, UE <NUM> and observing wireless network node <NUM> may perform channel sensing based on said information of the SSB, i.e., the first information and said information of the at least one part of the SIB1, i.e., the second information.

That is, UE <NUM> and observing wireless network node <NUM> may perform processing of the first information of the SSB and the second information of the at least one part of the SIB1. The processing of the first information and the second information may be performed by performing at least one of the following: channel sensing, skipping reception of the SIB1, skipping channel decoding of the SIB1, or considering the SIB1 as a known signal.

<FIG> illustrates a third example in accordance with at least some embodiments. In <FIG>, SSB <NUM>, CORESET#<NUM><NUM> and SIB <NUM><NUM> are illustrated as in <FIG>. In addition, unhanged, first part is denoted by <NUM> and variable, second part is denoted by <NUM>. As illustrated in <FIG>, CORESET#<NUM><NUM> and SIB1 <NUM> may be divided into two parts. First part <NUM> may comprise unchanged SIB1 and/or CORESET#<NUM> information, valid for sensing the channel and a second part <NUM> may comprise variable SIB1 and/or CORESET#<NUM> information, invalid for sensing. That is, first part <NUM> of SIB <NUM> may comprise unchanged information, compared to a previously decoded SIB1, and second part <NUM> of SIB <NUM> may comprise variable information.

In some example embodiments, first part <NUM> comprising unchanged SIB <NUM>/CORESET#<NUM> information may comprise persistent information similar to the PBCH. In case of any change in first part <NUM> comprising unchanged information, a cell reset procedure may be used. Second part <NUM> of SIB1/CORESET#<NUM> information may be freely varied in time-sensitive manner, as it might not be considered for sensing measurements.

In some example embodiments, the split between the two parts may be different for CORESET#<NUM><NUM> and SIB1 <NUM>. For instance, SIB1 <NUM> may comprise of unchanged part <NUM> and variable part <NUM> while CORESET#<NUM><NUM> may be unchanged. For instance, Control Channel Elements, CCEs, within CORESET#<NUM><NUM> used for type#<NUM> PDCCH may be unchanged. SSB <NUM>, and the PBCH, may be always unchanged.

In <FIG>, the diagonal split of the SIB1/CORESET#<NUM> block represents the possibility of having different multiplexing options for the unchanged and variable parts. Moreover, multiplexing of unchanged and variable parts in the SIB1/CORESET#<NUM> block may be performed in time and/or frequency domain, comprising also a possibility for comb-like structures. The exact split between the two parts may be indicated to all involved observers, like UE <NUM> and/or observing wireless network node <NUM>, in the beginning of the sensing process. Alternatively, the split may be defined in a standard, like a 3GPP standard.

<FIG> illustrates a fourth example in accordance with at least some embodiments. On the vertical axes are disposed, from the left to the right, UE <NUM>, source wireless network node <NUM> and observing wireless network node <NUM>. Time advances from the top towards the bottom. The fourth example illustrated in <FIG> is similar compared to the second example illustrated in <FIG>, because in both examples a sensing device, like UE <NUM> and/or observing wireless network node <NUM> may assume that a SIB1 is unchanged, compared to a previously decoded SIB1. However, unlike in the second example illustrated in <FIG>, wherein any changes in the SIB1 information may be signalled by source wireless network node <NUM>, in the fourth example illustrated in <FIG> the SIB1 may be considered as unchanged for a predefined time period, i.e., over a given time period.

Step <NUM> may correspond to step <NUM>. After setting up the initial sensing session configurations, source wireless network node <NUM> may indicate at step <NUM>, the time period for which the SIB1, and the information therein, may be assumed unchanged.

At step <NUM>, source wireless network node <NUM> may transmit a SSB and a SIB1. UE <NUM> and observing wireless network node <NUM> may detect and decode the SSB and SIB1, at steps <NUM> and <NUM>, respectively. UE <NUM> and observing wireless network node <NUM> may then determine, based on the decoded SSB and the decoded SIB1 information, i.e., content and arrangement, for sensing based on a SSB and at least one part of a SIB1, respectively.

Sensing with unchanged SIB1 may be ongoing for the predetermined time period at steps <NUM> and <NUM>. At step <NUM>, source wireless network node <NUM> may transmit the SSB and the SIB1 for sensing a channel. Similarly, at step <NUM>, source wireless network node <NUM> may transmit the SSB and the SIB1 again for sensing the channel. Consequently, UE <NUM> and observing wireless network node <NUM> may receive the SSBs and the SIB1s. UE <NUM> and observing wireless network node <NUM> may then perform channel sensing based on said information of the SSB and said information of the at least one part of the SIB1. The transmissions, at steps <NUM> and <NUM>, may be beam sweeping transmission.

After the time period expires, i.e., after step <NUM>, UE <NUM> and observing wireless network node <NUM> must again decode a SSB and a SIB1 if they wish to continue the sensing process. Alternatively, observing wireless network node <NUM> may be informed about a SIB1 change using interface <NUM>. Source wireless network node <NUM> may determine that there is a need to change said information in the SIB1 and, at step <NUM>, transmit the SSB and the changed SIB1 for sensing a channel. The transmission, at step <NUM>, may be a beam sweeping transmission. At steps <NUM> and <NUM>, UE <NUM> and observing wireless network node <NUM>, may detect and decode the SSB and the changed SIB1. The decoded changed SIB1 may be considered as a previously decoded SIB1. Hence, UE <NUM> and observing wireless network node <NUM> may detect and decode a SIB1 after the end of the time period, based on the previously decoded SIB1.

If needed, source wireless network node <NUM> may modify the time period during the sensing process by signalling a new time period to UE <NUM> and observing wireless network node <NUM>. Signalling between source wireless network node <NUM> and observing wireless network node <NUM> may be performed via inter-BS interface <NUM>, e.g., using an Xn-interface.

In some example embodiments, even though information in a SIB1 may change, predefined content, resources and/or format for SIB1 may not change. That is, a payload, time and frequency resources, coding, modulation, etc. are not changed. In the case of type#<NUM> PDCCH, the payload, aggregation level or CORESET#<NUM> resources used for type#<NUM> PDCCH may not be changed. UE <NUM> may obtain such information when it decodes SIB <NUM> correctly. That is, even though the SIB1 content, e.g., parameter values may change, the SIB1 size, and transmission parameters might not change.

In some example embodiments, a joint use of SSBs and SIB1s is therefore enabled, for example for bi-static sensing. Compared to using only SSBs, the joint use of SSBs and SIB <NUM> may provide wider bandwidth and enhanced measurement time-granularity. Hence, sensing performance, such as ranging accuracy and velocity estimation accuracy, may be improved substantially without increasing radio interface overhead.

In some example embodiments, each SSB may be divided into three parts, given as PSS, SSS and PBCH. The duration of a single SSB may be <NUM> Orthogonal Frequency Division Multiplexing, OFDM, symbols. The OFDM symbols may span over <NUM> subcarriers in frequency domain. With a subcarrier spacing of <NUM>, a SSB transmission may reach its maximum bandwidth of <NUM>. For example in Frequency Range <NUM>, FR1, and FR2, SSBs may be transmitted using beam sweeping. A set of SSBs may be transmitted with a full cycle of SSB-wise beams and referred to as a Synchronization Signal, SS, burst set. Depending on the used carrier frequency, one SS burst set may comprise a transmission of <NUM>-<NUM> beamformed SSBs. The duration of a single SS burst set may be always limited to <NUM>, and the full SS burst may be periodically repeated in every <NUM>-<NUM>. However, UEs performing an initial cell search may assume a maximum SS burst set interval of <NUM>.

Regarding sensing aspects, SSBs may offer an always-on signal which may be broadcasted over the complete cell area, and sensing can be carried in both idle and active states. However, due to the low bandwidth used for SSBs, the accuracy of SSB-based sensing may be rather limited. In addition, if only four consecutive OFDM symbols would be used a single SSB, the velocity accuracy estimation would be restricted.

In some example embodiments, SIBs may carry system information regarding the current cell as well as neighbouring cells and related carriers. From multiple SIB types, the essential information on accessing the system may be found from SIB1, which may be transmitted periodically and frequently enough for each SSB beam over the whole cell. However, in some example embodiments, a wireless network node may decide whether or not to transmit a SIB1 associated to certain SSB transmission. After decoding a MIB carried by the SSB in PBCH, decoding of SIB1, sometimes referred to as Remaining Minimum System Information, RMSI, may be needed in order to initiate the random access process. For this reason SIB1 may be transmitted in every <NUM> scheduled as common PDSCH transmissions.

The scheduling of SIB1 may be monitored through an associated CORESET information, referred to as type#<NUM> PDCCH or CORESET#<NUM>, whose resources in terms of search space may be indicated in the PBCH. Depending on the used Demodulation Reference Signal, DMRS, configuration, the CORESET#<NUM> block may be <NUM>-<NUM> OFDM symbols long. In frequency domain, a CORESET#<NUM> may be assigned to multiples of <NUM> PRBs and upper limited by the carrier bandwidth. In some example embodiments, CORESET#<NUM> transmission may refer to a type#<NUM> PDCCH transmission on CORESET#<NUM>. A type#<NUM> PDCCH may occupy whole CORESET#<NUM> or only a portion of CORESET#<NUM> resources, depending on the CORESET#<NUM> size and aggregation level used for type#<NUM> PDCCH.

From the channel sensing perspective, SIB1 and associated CORESET#<NUM>, which may be transmitted in identical directions with the SSBs, may be exploited to offer a significant increase in bandwidth compared to SSB. In addition, compared to SSB, SIB1 and CORESET#<NUM> may be used to provide a larger number of consecutive OFDM symbols. Therefore, together with the extended bandwidth and time duration, the sensing performance in terms of ranging and velocity estimation accuracy may be considerably improved compared to SSB. However, unlike with the SSBs, the information on SIB1/CORESET#<NUM> may not be fixed and may need to be occasionally modified, although the modification rate may be considered very low.

<FIG> illustrates an example apparatus capable of supporting at least some example embodiments. Illustrated is device <NUM>, which may comprise, for example, UE <NUM>, source wireless network node <NUM> or observing wireless network node <NUM>, or a control device configured to control the functioning thereof, possibly when installed therein. Comprised in device <NUM> is processor <NUM>, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor <NUM> may comprise, in general, a control device. Processor <NUM> may comprise more than one processor. Processor <NUM> may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. Processor <NUM> may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor <NUM> may comprise at least one application-specific integrated circuit, ASIC. Processor <NUM> may comprise at least one field-programmable gate array, FPGA. Processor <NUM> may be means for performing method steps in device <NUM>. Processor <NUM> may be configured, at least in part by computer instructions, to perform actions.

A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

Device <NUM> may comprise a transmitter <NUM>. Device <NUM> may comprise a receiver <NUM>. Transmitter <NUM> and receiver <NUM> may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter <NUM> may comprise more than one transmitter. Receiver <NUM> may comprise more than one receiver. Transmitter <NUM> and/or receiver <NUM> may be configured to operate in accordance with Global System for Mobile communication, GSM, Wideband Code Division Multiple Access, WCDMA, Long Term Evolution, LTE, and/or <NUM>/NR standards, for example.

Device <NUM> may comprise a Near-Field Communication, NFC, transceiver <NUM>. NFC transceiver <NUM> may support at least one NFC technology, such as Bluetooth, Wibree or similar technologies.

Device <NUM> may comprise User Interface, UI, <NUM>. UI <NUM> may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device <NUM> to vibrate, a speaker and a microphone. A user may be able to operate device <NUM> via UI <NUM>, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory <NUM> or on a cloud accessible via transmitter <NUM> and receiver <NUM>, or via NFC transceiver <NUM>, and/or to play games.

Device <NUM> may comprise or be arranged to accept a user identity module <NUM>. User identity module <NUM> may comprise, for example, a Subscriber Identity Module, SIM, card installable in device <NUM>. A user identity module <NUM> may comprise information identifying a subscription of a user of device <NUM>. A user identity module <NUM> may comprise cryptographic information usable to verify the identity of a user of device <NUM> and/or to facilitate encryption of communicated information and billing of the user of device <NUM> for communication effected via device <NUM>.

Device <NUM> may comprise further devices not illustrated in <FIG>. For example, where device <NUM> comprises a smartphone, it may comprise at least one digital camera. Some devices <NUM> may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the front-facing camera for video telephony. Device <NUM> may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device <NUM>. In some example embodiments, device <NUM> lacks at least one device described above. For example, some devices <NUM> may lack a NFC transceiver <NUM> and/or user identity module <NUM>.

Processor <NUM>, memory <NUM>, transmitter <NUM>, receiver <NUM>, NFC transceiver <NUM>, UI <NUM> and/or user identity module <NUM> may be interconnected by electrical leads internal to device <NUM> in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device <NUM>, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the example embodiment, various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the example embodiments.

<FIG> is a flow graph of a first method in accordance with at least some example embodiments. The apparatus of the first method is a UE <NUM> or observing wireless network node <NUM>, or a control device configured to control the functioning thereof, possibly when installed therein. That is, the steps of the first method are performed by UE <NUM> or observing wireless network node <NUM>, or by a control device configured to control the functioning thereof, possibly when installed therein.

The first method comprises, at step <NUM>, determining, by an apparatus, first information for reception of a synchronization signal block from a cell of a source wireless network node. The first method also comprises, at step <NUM>, determining, by the apparatus, second information for reception of at least one part of a system information block from the cell of the source wireless network node, wherein the second information is unchanged compared to at least one part of a previous system information block and determining third information for reception of a physical downlink control channel from the cell of the source wireless network node, wherein the third information is unchanged compared to a previous physical downlink channel. The first method further comprises, at step <NUM>, receiving, by the apparatus, the synchronization signal block and the system information block and receiving the physical downlink control channel. Finally, the first method comprises, at step <NUM>, performing, by the apparatus, processing of the first information of the synchronization signal block and the second information of the at least one part of the system information and performing channel sensing based on the first information of the synchronization signal block and the second information of the at least one part of the system information block and the third information of the physical downlink control channel.

It should be understood that terminology employed herein is used for the purpose of describing particular example embodiments only and is not intended to be limiting.

Reference throughout this specification to one example embodiment or an example embodiment means that a particular feature, structure, or characteristic described in connection with the example embodiment is included in at least one example embodiment. Thus, appearances of the phrases "in one example embodiment" or "in an example embodiment" in various places throughout this specification are not necessarily all referring to the same example embodiment.

In addition, various example embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such example embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations.

In an example embodiment, an apparatus, such as, for example, UE <NUM>, source wireless network node <NUM> or observing wireless network node <NUM>, may comprise means for carrying out the example embodiments described above and any combination thereof.

In an example embodiment, a computer program may be configured to cause a method in accordance with the example embodiments described above and any combination thereof. In an example embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a process comprising the example embodiments described above and any combination thereof.

In an example embodiment, an apparatus, such as, for example, UE <NUM>, source wireless network node <NUM> or observing wireless network node <NUM>, may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform the example embodiments described above and any combination thereof.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of example embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the disclosure can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

While the forgoing examples are illustrative of the principles of the example embodiments in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the disclosure. Accordingly, it is not intended that the disclosure be limited, except as by the claims set forth below.

At least some example embodiments find industrial application in cellular communication networks, for example in 3GPP networks.

Claim 1:
An apparatus (<NUM>, <NUM>, <NUM>) comprising means for:
- determining (<NUM>, <NUM>, <NUM>) first information for reception of a synchronization signal block from a cell of a source wireless network node;
- determining (<NUM>) second information for reception of at least one part of a system information block from the cell of the source wireless network node, wherein the second information is unchanged compared to at least one part of a previous system information block;
- determining third information for reception of a physical downlink control channel from the cell of the source wireless network node, wherein the third information is unchanged compared to a previous physical downlink channel;
- receiving (<NUM>) the synchronization signal block and the system information block;
- receiving the physical downlink control channel;
- performing processing (<NUM>, <NUM>) of the first information of the synchronization signal block and the second information of the at least one part of the system information block; and
- performing channel sensing based on the first information of the synchronization signal block and the second information of the at least one part of the system information block and the third information of the physical downlink control channel.