GB2569989A

GB2569989A - Paging in cellular communication systems

Info

Publication number: GB2569989A
Application number: GB1800247.7A
Authority: GB
Inventors: Assouline Benny; Cayron Noam; Palgy Michal; Marco Olivier; Liu Guang
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2018-01-08
Filing date: 2018-01-08
Publication date: 2019-07-10
Anticipated expiration: 2038-01-08
Also published as: GB201800247D0; CN111328453A; WO2019134537A1; GB2569989B

Abstract

A paging message to a UE in a cellular wireless communications network comprises a service indication indicating the service to which the paging message relates. On receipt of the message, the UE determines whether the currently camped-on cell can support the required service. If not, a cell reselection process is initiated. The paging message may comprise a UNI (UE-Network Slice Identification) which corresponds to at least one allowed S-NSSAI (single network slice selection assistance information). Alternatively the paging message comprises an S-TMSI corresponding to a service to be provided to the UE. A connection establishment message may be received from the UE and the network determines whether a service to be provided to the UE using the requested connection can be provided by the resources or cell to which the UE is connected. If the service cannot be provided the connection is refused and the UE is redirected to a resource or cell which can provide the service. The service indication may only be provided if the current cell cannot provide the service.

Description

Paging in Cellular Communication Systems

Technical Field

The following disclosure relates to paging systems for wireless cellular communication systems, and in particular to the indication of service information in conjunction with paging messages.

Background

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network where one or more macrocells are supported by a base station known as an eNodeB or eNB (evolved NodeB). More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB.

User Equipment (UE) connected by a wireless link to a Radio Access Network (RAN) do not necessarily remain in continuous communication with the RAN, but rather may enter an idle mode (typically an RRC state) in which there is only intermittent contact over the wireless link. A paging process is utilised to locate a specific UE in a cellular network, for example to establish a connection for a Mobile Terminating (MT) call, or other service. Paging messages are transmitted over one or more cells in which the UE may be located at predefined times. UEs are configured to listen to the cell on which they are camped at the predefined times to receive paging messages. If a UE receives a paging message the UE initiates an access procedure to establish a connection to the RAN.

Cellular communication standards define a range of services which may be provided by cellular networks, but not all cells of a network will necessarily support all services. When receiving a paging message a UE may thus be camped on a cell that does not support the service to which the paging message relates.

In conventional paging and access arrangements a UE is not aware of the service to which a paging message relates until a connection is established. For example, Figure 1 shows the process according to the LTE standards.

At step 100 the network transmits a paging message and at step 101 the UE initiates a contention-based random access procedure (CBRA), leading to a secured connection at step 102. At step 103 the network configures the UE with the appropriate measurement configuration and the UE transmits the measurement report to the network at step 104. The network now initiates, at step 105, handover to another cell which can support the required service, which entails a further access procedure (albeit potentially more efficient than the initial access procedure at step 101, for example a CFRA procedure). At step 106 the requested service can be started. The network-controlled handover cannot be initiated until receipt of the measurement reports such that there is significant delay and overhead, and also UE power consumption, before a connection is established which can support the required service.

The present invention is seeking to solve at least some of the outstanding problems in this domain.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

There is provided a method of paging a user equipment in a cellular wireless network, the method comprising the steps of determining a UE-Network Slice Instance Identification (UNI) applicable for a service for which a paging message is to be transmitted to a user equipment; and transmitting a paging message from a cell of a base station to the user equipment to be paged, wherein the paging message comprises the UNI.

The UNI may be a 3 bit field.

Values of the UNI field may correspond to at least one allowed S-NSSAI.

The paging message comprising the UNI may be only transmitted if the cell cannot support the service to which the paging message relates.

There is also provided a method of paging a user equipment in a cellular wireless network, the method comprising the steps of a user equipment receiving a paging message comprising a UE-Network Slice Instance Identification (UNI); the user equipment determining that the cell from which the paging message is received cannot support the service to which the paging message relates; and initiating a cell reselection procedure to establish a connection to a cell which can support the service to which the paging message relates.

The UNI may be a 3 bit field.

Values of the UNI field may correspond to at least one allowed S-NSSAI.

The user equipment may initiate cell reselection to a cell indicated in transmitted system information as providing the required service.

There is also provided a method of connection establishment performed in a cellular wireless network, the method comprising the steps of receiving a connection establishment message at a radio access network from a user equipment, determining whether a service to be provided to the user equipment using the requested connection can be provided by the resources to which the user equipment is connected; and if the service cannot be provided transmitting a message to the user equipment refusing the connection, wherein the message includes redirection information to a resource which can provide the service.

The redirection information may be to another frequency or radio access technology.

The redirection information may be to another cell, or a list of cells.

The radio access network may transmit a message to the user equipment refusing the connection, wherein the message includes a UE-Network Slice Instance Identification ID related to the service for which the connection is requested.

There is also provided a method of paging a user equipment in a cellular wireless network, the method comprising the steps of selecting an S-TMSI for a user equipment to be paged, wherein the S-TMSI is selected from a plurality of S-TMSIs assigned to the user equipment and corresponds to a service to be provided to the user equipment; and transmitting a paging message to the user equipment including the selected S-TMSI.

The S-TMSI may relate to an allowed S-NSSAI.

The method may further comprise the step of allocating a plurality of S-TMSI values to a corresponding to at least one allowed S-NSSAI, and transmitting an indication to a user equipment of the allocation.

There is also provided a method of paging a user equipment in a cellular wireless network, the method comprising the steps of configuring a user equipment with a set of S-TMSI values and corresponding service types; receiving a paging message at the user equipment comprising one of the configured S-TMSI values; determining whether the cell to which the user equipment is connected can provide the service indicated by the S-TMSI value; and initiating a cell reselection procedure if the cell cannot provide the indicated service.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

Brief description of the drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

Figure 1 shows a paging and handover process;

Figure 2 shows a paging process; and

Figure 3 shows a further example of a paging process.

Detailed description of the preferred embodiments

Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Figure 2 shows a process for paging including transmission of a service indication. At step 200 a paging message is transmitted from the network in at least one cell in which the UE being paged may be camped. The paging message may include a service indication indicating the service to be provided to the UE. The service indication may be provided in any appropriate manner.

In an example a service indication in the paging message is provided by a network slice Instance Identifier. The NR standards introduce the concept of a network slice which is a specific network supporting a particular service. Network slices allow network providers to create networks optimised for specific services. Network slices may be described by terminology including:-

Network Slice Instance (NSI) - A set of Network Function instances and the required resources (e.g. compute, storage, and networking resources) which form a deployed Network Slice. UE NSI ID (UNI) - An identifier for an NSI within the context of a single UE. NSSAI - Network Slice Selection Assistance Information. The NSSAI is a collection of S-NASSAIs. S-NSSAI - Single Network Slice Selection Assistance Information. An S-NSSAI can be associated with one or more Network Slice Instances. At most 8 S-NSSAIs can be included in signalling messages between a UE and the network.

When a UE is registering to a network, it provides the NW with requested NSSAI. The Requested NSSAI signalled by the UE to the network allows the network to select the Serving AMF, Network Slice(s) and Network Slice instance(s) for this UE and the UE is provided with allowed NSSAI. During registration, the UE is also provided with a pseudo random S-TMSI (5G-S-TMSI in the context of the 5G standards) used for paging.

In an example, the service indication in the paging message may be an NSI identifier. For example, a UNI may be utilised, which in a particular example may be a 3-bit field with values being mapped to S-NSSAIs allocated to the UE. The use of three bits corresponds to the limit of 8 allowed S-NSSAIs per UE.

The UE is provided during registration with mapping of the UE’s allowed S-NSSAI to a UNI value. For example, the first S-NSSAI in the allowed S-NSSAI message is implicitly assigned with UNI value 000, the second S-NSSAI in the allowed S-NSSAI message is implicitly assigned with UNI value 001 and so on. At paging time, this value should be also provided by the AMF to the base station (eNB/gNB) over the NG-C interface to be included as part of the paging record. In order to support the same functionality with RAN level paging (i.e. in RRCJNACTIVE) the UNI mapping to allowed S-NSSAI may be added to the RAN UE context.

Messaging, for example across the NG interface, between the core network and RAN may be modified to communicate the required UE-NSI ID (UNI) to the RAN.

Upon receipt of the paging message, at step 201 the UE determines whether the cell on which it is currently camped can support the required service. If the service can be supported at step 202 a conventional connection establishment procedure is initiated to the currently camped cell. However, if the service cannot be supported, at step 203 a cell reselection process is initiated to establish a connection to a cell which can support the required service. As set out below a specific cell reselection procedure may be utilised to make this process more efficient. A connection establishment procedure is then conducted to the new cell at step 204.

Utilising the UNI as set out in the specific example incurs a 3-bit overhead on each paging message, but provides reduced latency to the service being established and corresponding reduction in UE power consumption.

In a further example, the service indication may be provided by utilising S-TMSI values related to the paged service. As noted above, during registration a UE is provided with a pseudo-random S-TMSI which is used for paging the UE. During the registration process the UE may be provided with a different S-TMSI for each allowed S-NSSAI (while one of the provided S-TMSI or another S-TMSI is assigned to be used for other procedures such as calculation of paging occasions) and an indication of the relationship from S-TMSI to S-NSSAI. When paging a UE for a particular service the network can then use the appropriate S-TMSI corresponding to the service, and upon receipt the UE can determine which service is required. The UE can then initiate cell reselection if required to provide the required service. Such a method does not incur a signalling overhead, but is limited by the number of UEs that can be supported per AMF.

Figure 3 shows a further example of a paging process allowing selection of an appropriate cell for a service. At step 300 a conventional paging message is transmitted and at step 301 the relevant UE initiates a connection establishment procedure. If the cell can provide the required service the connection establishment procedure is conducted as normal, but if the service cannot be provided by the relevant cell the connection request is rejected at step 302. For example, in a CBRA procedure the network may reject the request in Msg4, and in a CFRA procedure in Msg2. The connection rejection may include redirection information to assist the UE in selecting an appropriate cell.

Redirection information in the rejection message 302 may include redirection to another frequency, RAT, or cell/list of cells. Alternatively, the rejection message may include a network slice indication (for example the UNI field discussed above). Redirection information for each service may be broadcast in the SI.

At step 303 the UE initiates the cell reselection procedure to establish a connection to a cell that can provide the required service, utilising the information received in the rejection message as appropriate.

The process described with reference to Figure 3 thus avoids the completion of a full connection establishment procedure before redirecting the UE to a cell that can provide the required service.

In the above examples, the service indication may be included only if the relevant cell cannot provide the required service. That is, if the cell can provide the service the service indication is not included and the UE will respond to the paging message in the conventional manner. Since paging messages may be transmitted on multiple cells a different message may be transmitted in different cells depending on the capabilities of the cell such that the UE receives the correct indication for the cell the UE is camped on. If the UE receives an indication of the service required, it can therefore assume that the current cell cannot provide the required service and can thus commence reselection.

For Mobile Originating communications the higher layers of the UE (i.e. higher than the radio layer, for example the application layer) may inform the UE of the service required. If the cell on which the UE is camped broadcasts redirection information (for example over SI) for the required service the UE assumes the cell cannot provide the service and initiates a reselection process.

Any appropriate method may be utilised to broadcast service indication and/or redirection information. As discussed above a cell may broadcast redirection information for services that are not supported. Alternatively cells may broadcast a list of supported services and a UE can assume other services are not provided. In a further alternative a list of services that are not supported may be broadcast, thus providing a direct indication that cell reselection will be required.

If redirection information is available for a required service the UE reconsiders the indicated supporting frequencies/RATs to have the highest priority for cell reselection procedure and triggers a new cell reselection procedure. If a list of specific cell IDs are indicated as supporting the required service, the UE reselects to the highest ranking cell amongst the list of supporting cells.

The paging processes described hereinbefore may be applied to both core network and radio area network initiated paging (for example in NR for paging a UE in RRCJNACTIVE state, or in EUTRAN for a suspended UE).

The invention has been described with respect to the examples and scenarios mentioned above. However, the invention may also apply to other situations and scenarios, such as for example, indication existence of very small packets of, e.g., gaming or remote control, services transmitted in similar way as pre-empting ongoing transmissions.

Although not shown in detail any of the devices or apparatus that form part of the network may include at least a processor, a storage unit and a communications interface, wherein the processor unit, storage unit, and communications interface are configured to perform the method of any aspect of the present invention. Further options and choices are described below.

The signal processing functionality of the embodiments of the invention especially the gNB and the UE may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a processor.

The computing system may also include an information storage system which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (CD) or digital video drive (DVD) read or write drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

In alternative embodiments, an information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, a removable storage unit and an interface , such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

In this document, the terms ‘computer program product’, ‘computer-readable medium’ and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally referred to as ‘computer program code’ (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory

In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module (in this example, software instructions or executable computer program code), when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP), or application-specific integrated circuit (ASIC) and/or any other sub-system element.

It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organisation.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented, at least partly, as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices. Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to ‘a’, ‘an’, ‘first’, ‘second’, etc. do not preclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ or “including” does not exclude the presence of other elements.

Claims

1. A method of paging a user equipment in a cellular wireless network, the method comprising the steps of determining a UE-Network Slice Instance Identification (UNI) applicable for a service for which a paging message is to be transmitted to a user equipment; and transmitting a paging message from a cell of a base station to the user equipment to be paged, wherein the paging message comprises the UNI.

2. A method according to claim 1, wherein the UNI is a 3 bit field.

3. A method according to claim 1 or claim 2, wherein values of the UNI field correspond to at least one allowed S-NSSAI.

4. A method according to claim 1, wherein the paging message comprising the UNI is only transmitted if the cell cannot support the service to which the paging message relates.

5. A method of paging a user equipment in a cellular wireless network, the method comprising the steps of a user equipment receiving a paging message comprising a UE-Network Slice Instance Identification (UNI); the user equipment determining that the cell from which the paging message is received cannot support the service to which the paging message relates; and initiating a cell reselection procedure to establish a connection to a cell which can support the service to which the paging message relates.

6. A method according to claim 5, wherein the UNI is a 3 bit field.

7. A method according to claim 5 or claim 6, wherein values of the UNI field correspond to at least one allowed S-NSSAI.

8. A method according to any of claims 5 to 7, wherein the user equipment initiates cell reselection to a cell indicated in transmitted system information as providing the required service.

9. A method of connection establishment performed in a cellular wireless network, the method comprising the steps of receiving a connection establishment message at a radio access network from a user equipment, determining whether a service to be provided to the user equipment using the requested connection can be provided by the resources to which the user equipment is connected; and if the service cannot be provided transmitting a message to the user equipment refusing the connection, wherein the message includes redirection information to a resource which can provide the service.

10. A method according to claim 9, wherein the redirection information is to another frequency or radio access technology.

11. A method according to claim 9, wherein the redirection information is to another cell, or a list of cells.

12. A method according to claim 9, wherein the radio access network transmits a message to the user equipment refusing the connection, wherein the message includes a UE-Network Slice Instance Identification ID related to the service for which the connection is requested.

13. A method of paging a user equipment in a cellular wireless network, the method comprising the steps of selecting an S-TMSI for a user equipment to be paged, wherein the S-TMSI is selected from a plurality of S-TMSIs assigned to the user equipment and corresponds to a service to be provided to the user equipment; and transmitting a paging message to the user equipment including the selected S-TMSI.

14. A method according to claim 14, wherein the S-TMSI relates to an allowed S-NSSAI.

15. A method according to claim 13 or claim 14, further comprising the step of allocating a plurality of S-TMSI values to a corresponding to at least one allowed S-NSSAI, and transmitting an indication to a user equipment of the allocation.

16. A method of paging a user equipment in a cellular wireless network, the method comprising the steps of configuring a user equipment with a set of S-TMSI values and corresponding service types; receiving a paging message at the user equipment comprising one of the configured S-TMSI values; determining whether the cell to which the user equipment is connected can provide the service indicated by the S-TMSI value; and initiating a cell reselection procedure if the cell cannot provide the indicated service.