WO2018007642A1

WO2018007642A1 - Mobility node selection

Info

Publication number: WO2018007642A1
Application number: PCT/EP2017/067209
Authority: WO
Inventors: Lars-Bertil Olsson; Tomas BRÄNNLUND; Jonas Nilsson; Björn NORDSTRÖM
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-07-08
Filing date: 2017-07-10
Publication date: 2018-01-11

Abstract

A method for an access node (AN), and an apparatus such as an eNodeB, eNB, being adapted for per-forming radio access at least to a specific Internet of Things (IoT) device and a legacy mobile broad band device, the AN communicating with an IoT mobile management node (IoT MME) and a legacy mobile broadband mobility management node (MBB MME), the method comprising: - receiving (110) a Radio Resource Connection (RRC), connection setup complete message (34), - assessing (140) UE capability information (140) as to specific IoT device capability for the UE, or legacy mobile broad band device capability. Then - if specific IoT device capabilities for the UE is found, selecting (155) the IoT MME, - if legacy MBB device capabilities for the UE is found, selecting (150) the MBB MME, - transmitting (160) a Network Access Stratum message, NAS message (42, 44), to the selected MME.

Description

Mobility node selection

This invention is directed to a selection of core net resources for among other Internet of Things, loT, devices.

Background

In the prior art, the selection of a MME (Mobility Management Entity) for a given UE (User Equipment) depends on the PLMN (Public Land Mobile Network).

In figj. a prior art solution based on 3GPP TS 36.331 v 13.1 .0 (2016-04) and 3GPP TS 36.413 v 13.2.0 (2016-03), both 3GPP RAN (Radio Access Network) specifications is indicated.

- The use of RRC (Radio Resource Control) signalling (as illustrated by the included flows 32 - 34 as the signalling between UE and the eNB (E-UTRAN NodeB)) is specified by 36.331 ,

- The use of S1 AP (S1 Application Protocol) signalling (as illustrated by the included flow 42 as the signalling between eNodeB and MME) is specified by 36.413.

In 3GPP Release 13, two main device types have been defined supporting loT. Narrow band loT, N B-loT is one such type and the other is UE Category M1 , Cat-M1 .

Cat-M1 allows an extended battery life of more than 10 years for a wide range of ma- chine type communication use cases mainly through the use of power saving mode

(PSM) and extended idle-mode Discontinuous Reception (eDRX), and connected mode eDRX, Cellular loT (CloT) control plane and user plane Evolved Packet System (EPS) optimisations for small data-transmission. Narrowband loT (NB-loT) is a 3GPP Release 13 feature that reuses various principles and building blocks of the LTE physical layer and higher protocol layers to enable rapid standardisation and product development. NB-loT has been designed to offer extended coverage compared to the traditional GSM networks. Summary

It is an object of the present invention to set forth improved apparatuses and methods for Internet of Things device handling. It is envisioned by the inventors of the present appli- cation, that an operator with a cellular network may want to have separate Core Network (CN) resources for different types of devices. By way of example, the operator may want to handle all Internet of Things (loT) devices using CN resources separated from the CN resources used to handle legacy (Mobile Broadband, MBB) E-UTRAN (Evolved Universal Terrestrial Radio Access Network) devices.

When a UE requests to become RRC (Radio Resource Control) connected in an E-UTRAN cell where the UE is not registered by the core network, the serving MME may not be available to continue to serve the UE in the particular cell. In that case, the eNB must make an MME selection using the NAS (Network Access Stratum) Node Selection Func- tion (NNSF).

An embodiment of the present invention is related to the NNSF logic and information used as input for deciding which MME to select for the UE when the UE is not registered by any of the available MMEs.

According to an aspect of the invention there is defined a method for an access node, AN, such as an eNodeB, eNB, being adapted for per-forming radio access at least to a specific Internet of Things, loT, device and a legacy mobile broad band device, the AN communicating with an loT mobile management node, loT MME and a legacy mobile broadband mobility management node, MBB MME,

the method comprising

- receiving a Radio Resource Connection, RRC, connection setup complete message,

- assessing UE capability information as to specific loT device capability for the UE, or legacy mobile broad band device capability.

Then - if specific loT device capabilities for the UE is found, selecting the loT MME,

- if legacy MBB device capabilities for the UE is found, selecting the MBB MME,

- transmitting a Network Access Stratum message, NAS message, to the selected MME.

There is also provided a method for a loT user entity, UE, adapted for communicating with an Access Node, AN, comprising - transmitting a Radio Resource Connection, RRC, connection setup complete message, to a AN,

upon receiving a UE capability enquiry from the AN

- UE capability information to the AN concerning specific loT device capabilities.

There is further provided an access node, AN, such as an eNodeB, eNB, being adapted for per-forming radio access at least to a specific Internet of Things, loT, device and a legacy mobile broad band device, the AN communicating with an loT mobile management node, loT MME and a legacy mobile broadband mobility management node, MBB MME,

the AN comprising a processor and a memory having stored therein instructions being configured to

- assessing UE capability information as to specific loT device capability for the UE, or legacy mobile broad band device capability,

- if specific loT device capabilities for the UE is found, selecting the loT MME,

- if legacy MBB device capabilities for the UE is found, selecting the MBB MME,

- transmitting a Network Access Stratum message, NAS message, to the selected MME. Further, there is provided an Internet of things, loT user entity, UE, adapted for communicating with an Access Node, AN, the UE comprising a processor, and memory comprising instructions adapted for

- transmitting a Radio Resource Connection, RRC, connection setup complete message, to a AN,

Upon receiving a UE capability enquiry from the AN, the UE is

- transmitting 39 UE capability information to the AN concerning specific loT device capabilities.

The Internet of Tings, loT, user entity, UE, may be a Category M, Cat-M1 , UE.

The specific loT device capability may correspond to a Category M1 UE, Cat-M1 UE and the legacy mobile broad band device capability may correspond to Wide Band Evolved Universal Terrestrial Radio Access, WB-E-UTRAN, devices except Cat-M1 devices. More specifically, this invention makes it possible for the eNB to treat Cat-M1 devices differently compared to non-Cat-M1 devices in the NNSF, hereby allowing the operator to have separate and dedicated CN resources to serve loT traffic from Cat-M1 devices.

Brief description of the drawings

Fig. 1 shows an exemplary scenario for a known transmission procedure, fig. 2 shows an exemplary signalling flow for a selection and transmission procedure according to an embodiment of the invention, fig. 3 is a flow diagram relating to fig. 2, and fig. 4 shows embodiments of an access node, e Node B, eNB, a Mobile Broadband

MME, a loT MME and a user entity, UE.

Detailed description

An NB-loT device will access the eNB in a NB-loT cell. The scenario will be obvious for the eNB when decoding the signals from the UE when it finds that a NB-loT UE seeks access, because of separate NB-loT channels are defined that will only be accessed by NB-loT devices. This means that it will be straightforward for the NNSF to identify ac- cess attempts by NB-loT devices and discriminate such attempts from access attempts by legacy (MBB) devices. With use of local configuration at the eNB, the eNB is aware of which particular MMEs that are suitable to serve NB-loT devices and the eNB selects one such suitable MME as target for the S1AP Initial UE Message. For Cat-M1 devices it is not equally straightforward. A Cat-M1 device will access the network using CE (Coverage Enhancement) PRACH (Physical Random Access Channel) resources. Such CE PRACH resources are separate from normal PRACH resources in a cell in frequency, time and/or preamble domain. However, it is a problem that also other devices than Cat-M1 can use CE PRACH resources to access the network. More specif- ically, UEs that are in bad coverage and have support for Coverage Enhancement (CE) may also access via CE PRACH. To enable eNB to select a CN resource suitable to serve a Cat-M1 device there is a need to do something out of the ordinary: if the NNSF were to always forward UEs that have accessed via CE PRACH also non-Cat-M1 UEs that support Coverage Enhance- ment would fall into this category: i.e. the solution is unable to detect Cat-M1 devices. The information available to eNodeB from using the normal RRC connection setup signalling does not include sufficient information to enable eNB to identify Cat-M1 devices. The available information makes it possible to identify a device which is using E-UTRAN and is handled using coverage enhancement but not to identify Cat-M1 alone.

According to an embodiment of the invention, the following is provided:

The eNodeB has as part of a connection request from a UE received an RRC message RRC Connection Request with no S-TMSI (SAE-Temporary Mobile Subscriber Identity) included, and, as part of the same connection request, also received an RRC message RRC Connection Setup Complete message. The absent S-TMSI from the RRC message RRC Connection Request is a consequence from that the UE has detected that the cell is not included as part of its registered area.

The RRC message RRC Connection Setup Complete is able to convey a GUMMEI (Globally Unique Mobility Management Entity Identifier) value as the message I E (Information Element) registered MME.

For the case when the RRC Connection Setup Complete either does not include a GUMMEI parameter or when an included GUMMEI is not associated with an available MME, the eNodeB is triggered to perform MME selection.

If the network in which the eNodeB is part supports use of enhanced coverage, and the UE has accessed the network via the CE PRACH resources, the eNodeB shall

- Temporarily store the received UE-related data

- Start the UE Capability Enquiry procedure and by that request the UE to send the UE Capability Information message as response

- Use the content of a received UE Capability Information message to determine if the UE is a Cat-M1 device.

- If the UE is a Cat-M1 device, let NNSF select an MME which is suitable to serve Cat- M1 .

- If the UE is not a Cat-M1 device, use NNSF to - select an MME which is suitable to serve any E-UTRAN device,

alternatively,

- select an MME which is suitable to serve WB-E-UTRAN devices except for Cat-M1 devices.

In fig. 2 an embodiment of the invention is shown in more detail.

The UE transmits a RRC connection request with an establishment cause and a UE ID set to a random value, 32, to the eNB.

The eNB performs RRC connection setup, 33.

The UE responds with a RRC connection setup complete message including message information elements registered MME and selected PLMN, 34.

The eNB determines 120 that additional information is needed for selecting a suitable MME and queries 38, the UE of its UE capabilities.

The UE responds with a message 39 comprising the capability information, e.g. whether it is a specific loT device such as a Cat-M1 device.

Based on this information, the eNB selects 150-155 the suitable MME and transmits message 42 or 44 depending on the selection. Both messages 42 and 44 are the S1AP Initial UE message and comprises a NAS message such as a NAS Attach Request message.

If the UE is not a Cat-M1 device, and the MBB MME is intended to serve devices which are not of type Cat-M1 , the MBB MME is selected and message 42 is transmitted to the MBB MME.

If the UE is a Cat-M1 device, and the loT MME is intended to serve devices which are of type Cat-M1 , the loT MME is selected and message 44 is transmitted to the loT MME. Advantages of embodiments of the invention The operator can easily deploy separate CN resources dedicated to serve

- Cat-M1 devices alone

- loT devices (loT devices in this context including NB-loT devices and Cat-M1 devices) separately from other network use.

According to embodiments of the invention, an obstacle is overcome that the operator may only differentiate between a use of coverage enhancement and no use of coverage enhancement.

According to embodiments of the invention, the operator is enabled to select CN resources specifically designated to serve Cat-M1 devices, the combination of Cat-M1 and NB-loT devices, and all E-UTRAN except Cat-M1 devices.

In fig. 3, a flow diagram pertaining to an Access Node, AN, such as an eNB is shown.

In step 1 10, An RRC Connection Request Complete message 34 is received, by AN.

In 120, it is assessed whether additional information is needed for MME selection.

In step 130, the AN requests 38 and potentially receives 39 UE capability information. In 140, the UE capability information is assessed and if the UE is not of type Cat-M1 step 150 select MBB MME is carried out and if the UE is of type Cat-M1 step 155 select loT MME is carried out.

Consequently, in step 160, a S1AP message such as a NAS Attach Request is transmit- ted by the AN to the selected MME.

In fig. 4, embodiments of an access node, AN, e.g. an E-UTRAN Node B, eNB, a Mobile Broadband MME, MBB MME, an loT MME and a user equipment, UE, are shown.

The eNB comprises a processor PCU_N and a memory MEM_N having stored therein instructions being configured to, when carried out on the processor PCU_N, carrying out the steps shown in the figures above. The eNB is moreover comprising and interface IF_N, through which the eNB communicates with other nodes. The MBB MME comprises a processor PCU_M and a memory MEM_M having stored therein instructions being configured to, when carried out on the processor PCU_M, carrying out the steps shown in the figures above. The MBB MME moreover comprises and interface I F_M, through which the MBB MME communicates with other nodes.

The loT MME comprises a processor PCIM and a memory MEMJ having stored therein instructions being configured to, when carried out on the processor PCIM , carrying out the steps shown in the figures above. The loT MME moreover comprises and interface I F_I , through which the loT MME communicates with other nodes.

There is also shown a user equipment, UE, comprising a processor, UE_PCU, memory, UE_MEM and an interface, I F_UE. The processor is adapted to carry out instructions as described above, which instructions are moreover adapted to be stored in the memory of the UE, UE_MEM. The UE communicates with the eNB through the interface I FJJE.

There are also provided computer programs and computer program products according to the above description.

In other words there is provided:

A method for an access node, AN, such as an eNodeB, eNB, being adapted for performing radio access at least to a specific Internet of Things, loT, device and a legacy mobile broad band device, the AN communicating with an loT mobile management node, loT MME and a legacy mobile broadband mobility management node, MBB MME, the method comprising

- receiving 1 10 a Radio Resource Connection, RRC, connection setup complete message 34,

- assessing 140 UE capability information 140 as to specific loT device capability for the UE, or legacy mobile broad band device capability.

Then - if specific loT device capabilities for the UE is found, selecting 155 the loT MME,

- if legacy MBB device capabilities for the UE is found, selecting 150 the MBB MME,

- transmitting 160 a Network Access Stratum message, NAS message 42, 44, to the selected MME.

The specific loT device capability may correspond to a Category M1 UE, Cat-M1 UE and wherein the legacy mobile broad band device capability corresponds to Wide Band Evolved Universal Terrestrial Radio Access, WB-E-UTRAN, devices except Cat-M1 devices.

There is also provided a method for a loT user entity, UE, adapted for communicating with an Access Node, AN, comprising

- transmitting a Radio Resource Connection, RRC, connection setup complete message 34, to a AN,

upon receiving a UE capability enquiry from the AN

The UE may be a Category M, Cat-M1 , UE and the UE capability information is then Cat-M1 UE capability.

the AN comprising a processor PCU_N and a memory MEM_N having stored therein in- structions being configured to

- assessing 140 UE capability information 140 as to specific loT device capability for the UE, or legacy mobile broad band device capability,

- if specific loT device capabilities for the UE is found, selecting 155 the loT MME,

- transmitting 160 a Network Access Stratum message, NAS message 42, 44, to the selected MME. The specific loT device capability may correspond to a Category M1 UE, Cat-M1 UE and the legacy mobile broad band device capability may correspond to Wide Band Evolved Universal Terrestrial Radio Access, WB-E-UTRAN, devices except Cat-M1 devices.

Further, there is provided an Internet of things, loT user entity, UE, adapted for com- municating with an Access Node, AN, the UE comprising a processor UE_PCU, and memory UE_MEM comprising instructions adapted for - transmitting a Radio Resource Connection, RRC, connection setup complete message 34, to a AN,

Upon receiving a UE capability enquiry from the AN, the UE is

The Internet of Tings, loT, user entity, UE, may be a Category M, Cat-M1 , UE and the UE capability information then concerns a Cat-M1 UE capability.

Claims

Method for an access node, AN, such as an eNodeB, eNB, being adapted for performing radio access at least to a specific Internet of Things, loT, device and a leg acy mobile broad band device, the AN communicating with an loT mobile manage ment node, loT MME and a legacy mobile broadband mobility management node, MBB MME,

the method comprising

- receiving (1 10 a Radio Resource Connection, RRC, connection setup complete message (34),

- assessing (140) UE capability information (140) as to specific loT device capability for the UE, or legacy mobile broad band device capability,

- if specific loT device capabilities for the UE is found, selecting (155) the loT MME,

- if legacy MBB device capabilities for the UE is found, selecting (150) the MBB MME,

- transmitting (160) a Network Access Stratum message, NAS message (42, 44), to the selected MME.

Method according to 1 wherein the specific loT device capability corresponds to a Category M1 UE, Cat-M1 UE and wherein the legacy mobile broad band device capability corresponds to Wide Band Evolved Universal Terrestrial Radio Access, WB-E-UTRAN, devices except Cat-M1 devices.

Computer program or computer program product according to claims 1 or 2.

4. Method for a loT user entity, UE, adapted for communicating with an Access Node, AN, comprising

- transmitting a Radio Resource Connection, RRC, connection setup complete message (34), to a AN, upon receiving a UE capability enquiry from the AN

5. Method according to claim 4, wherein the UE is a Category M, Cat-M1 , UE and the UE capability information is Cat-M1 UE capability.

6. Computer program or computer program product according to claims 4 or 5.

7. Access node, AN, such as an eNodeB, eNB, being adapted for performing radio access at least to a specific Internet of Things, loT, device and a legacy mobile broad band device, the AN communicating with an loT mobile management node, loT MME and a legacy mobile broadband mobility management node, MBB MME, the AN comprising a processor (PCU_N) and a memory (MEM_N) having stored therein instructions being configured to

- receiving (1 10) a Radio Resource Connection, RRC, connection setup complete message (34),

- if legacy MBB device capabilities for the UE is found, selecting (150) the MBB MME, and - transmitting (160) a Network Access Stratum message, NAS message (42, 44), to the selected MME.

Access node, AN, according to claim 7 wherein the specific loT device capability corresponds to a Category M1 UE, Cat-M1 UE and wherein the legacy mobile broad band device capability corresponds to Wide Band Evolved Universal Terrestrial Radio Access, WB-E-UTRAN, devices except Cat-M1 devices.

Internet of things, loT user entity, UE, adapted for communicating with an Access Node, AN, the UE comprising a processor (UE_PCU), and memory (UE_MEM) comprising instructions adapted for

- transmitting a Radio Resource Connection, RRC, connection setup complete message (34), to a AN, and upon receiving (38) a UE capability enquiry from the AN

- transmitting (39) UE capability information to the AN concerning specific loT device capabilities.

Internet of Tings, loT, user entity, UE, according to claim 9, wherein the UE is a Category M, Cat-M1 , UE and the UE capability information is Cat-M1 UE device capability.