TECHNICAL FIELD

The present disclosure generally relates to the field of wireless network communications, and, more particularly, to mobile alert systems.

BACKGROUND

In Long Term Evolution (LTE), there is a feature for providing Public Warning System (PWS) notifications to user equipments (UEs) that can be used to provide warning messages to users. For example, if there is an earthquake, the network can indicate this to the UEs by broadcasting PWS messages. This is expected to be introduced for New Radio (NR) as well.

The PWS messages for the Earthquake and Tsunami Warning System (ETWS) are broadcast in SystemInformationBlockType10 (ETWS primary notification) or SystemInformationBlockType11 (ETWS secondary notification), and PWS-messages for the Commercial Mobile Alert System (CMAS) are broadcast in SystemInformationBlockType12. These system information block types are defined in the LTE Radio Resource Control (RRC) specification 3GPP TS 36.331. It should be noted that other types of Public Warning Systems include European Union (EU) Alert and Korean Public Alert System (KPAS).

If an ETWS secondary notification message or a CMAS notification message is large, the message can be divided into several segments and the segments are sent sequentially to the UE. There can be at most 64 segments, per the specifications for LTE, and the base station (e.g., eNB) indicates the number of each segment. Further, the eNB can indicate whether a certain segment is the last segment or not. When the UE has acquired all segments of a message, the RRC-layer in the UE reassembles all segments and forwards them to upper layers, to be presented to the user. Segmentation is not supported for the ETWS primary notification message, because it is a small message that is intended to be received by the UEs within a very limited time frame.

It is possible to send multiple PWS messages by sending them sequentially. So, if a first and a second message is to be sent to the UE, the eNB would first send all segments of the first message and then send all the segments of the second message. Each message can be sent periodically. Each message is further associated with a message identifier and a serial number.

Some PWS notifications may only be applicable for certain areas, such as an area close to a mall. To ensure that only users that are within the area are getting these notifications, the PWS notifications may have an associated area indication. This may, for example, be implemented by only providing the PWS notification in only one, or some, cells. As an alternative, the PWS notification can be included in an RRC message with an indication of the applicable area. The UE, upon receiving the PWS notification, determines whether it is inside or outside the area. If the UE is inside the area, the UE would then display the indication to the user. Otherwise, the UE will not display the indication.

In LTE and NR, system information is sent in so-called System Information Blocks (SIBs). In LTE, the physical layer imposes a limit to the maximum size of an SIB. When downlink control information (DCI) format 1C is used, the maximum allowed by the physical layer is 1736 bits (217 bytes) while for format 1A the limit is 2216 bits (277 bytes) (TS 36.212 and TS 36.213). For bandwidth-reduced low-complexity (BL) UEs and UEs in enhanced coverage (CE), the maximum SIB and system information message size is 936 bits (TS 36.213). For narrowband Internet-of-Things (NB-IoT), the maximum SIB and system information size is 680 bits (TS 36.213).

In LTE systems, CMAS PWS messages are sent in SystemInformationBlockType12. SystemInformationBlockType12 has a mandatory present field carrying a segment of, or the complete, PWS message. This means that the network must send at least a segment of a PWS message each time it sends SystemInformationBlockType12.

A legacy UE that receives, for example, a SystemInformationBlockType12 must be able to successfully decode the message. The corresponding requirement applies for SystemInformationBlockType11 (for ETWS secondary notification) and for SystemInformationBlockType10 (for ETWS primary notification). The latter however always includes the full message (ETWS primary notification) in a single SystemInformationBlockType10.

SUMMARY

Area information for public warning system (PWS) messages may be large when providing information for complex area structures. To be able to send this information for complex area structures, the PWS messages may need to be segmented into smaller parts, in order to fit in a transmission of a SIB. In some cases, the PWS message may be small and thus can be sent in a small number of segments, while the associated area information is large and thus requires a larger number of segments in order to transmit them. The embodiments described herein enable a network node to account for the sizes of both the PWS message and area information when transmitting the PWS message and area information via system information. The PWS messages and their associated area information can be segmented such that they can be sent to UEs via the system information.

In a first example, the network may segment area information for a PWS message such that the number of segments for the PWS message is at least as large as the number of segments of the area information. In another example, the network may extend the PWS message such that it can be segmented into at least as many segments as needed for the area information. In a third example, the network may send the PWS message in a first SIB and send the associated area information in a second SIB. The UE receiving the PWS message can receive and assemble the segments for the PWS message in the SIBs and then display the PWS message to the user if the UE determines from the area information that the PWS message is relevant to the user.

According to some embodiments, method, in at least one network node of a wireless communication system serving a plurality of UEs, includes obtaining a message to be transmitted as a public warning system notification to multiple UEs, via one or more SIBs. The method also includes obtaining area information corresponding to the message, the area information indicating an area for which the message is relevant and determining how many SIBs are needed for transmitting the area information. The method further includes segmenting the message into a plurality of segments, based on how many SIBs are needed for transmitting the area information and transmitting the message and the area information via SIBs, such that no more than one segment of the message is included in any of the transmitted SIBs and such that each portion of the area information included in a transmitted SIB is accompanied by a segment of the message.

According to some embodiments, a method, in at least one network node of a wireless communication system serving a plurality of UEs, includes obtaining a message to be transmitted as a public warning system notification to multiple UEs, via one or more SIBs, and obtaining area information corresponding to the message, where the area information indicates an area for which the message is relevant. The method further includes transmitting at least some of the message via a first SIB and transmitting at least some of the area information via a second SIB, such that the second SIB contains linking information indicating that the included area information corresponds to the message sent via the first SIB.

According to some embodiments, a method, in a UE served by a wireless communication network, includes receiving a plurality of SIBs. The method includes obtaining, from each of the SIBs, a portion of area information indicating an area for which a public warning system notification is relevant, and obtaining, from each of these same SIBs, a segment of a message. The method also includes assembling area information from the portions of area information and assembling the message from at least the corresponding segments of the message. The method further includes determining, based on the area information, that the message is relevant to the UE and displaying the message, in response to the determining.

According to some embodiments, a method, in a UE served by a wireless communication network, includes receiving at least a portion of a public warning system notification message via a first SIB and receiving at least a portion of area information via a second SIB. The method further includes determining, based on linking information included in the second SIB, that the area information included in the second SIB corresponds to the message received via the first SIB and determining, based on the area information, that the message is relevant to the UE. The method further includes displaying the message, in response to the determining.

Further aspects of the present invention are directed to an apparatus, network node, base station, wireless device, UE, computer program products or computer readable storage medium corresponding to the methods summarized above and functional implementations of the above-summarized apparatus and UE.

Of course, the present invention is not limited to the above features and advantages. Those of ordinary skill in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

