CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/EP2019/053333, filed Feb. 11, 2019, which claims priority to EP 18157035.9, filed Feb. 15, 2018, the entire contents of each are incorporated herein by reference.

BACKGROUND

Field

The present disclosure relates to wireless communications apparatus and methods for the transmission of an identifier generated by a core network entity to a radio access network entity by a mobile device.

Description of Related Art

The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.

As mobile telecommunications technology has developed, successive generations of technology have resulted in not only new radio techniques, which are typically implemented in a radio access network and at the lower layers of the protocol stack of a wireless communications device, but also in developments to so-called ‘core network’ functionality and the corresponding higher layer protocols. Nodes or entities within a radio access network typically provide geographically localised service to mobile devices within their respective localities. On the other hand, a single core network entity may serve many radio access network entities, providing services such as security (encryption), charging, and addressing.

In principle, functionality may be divided between the core network and a radio access network (and their respective protocols) in any appropriate manner; however, typically a core network will provide functionality that is independent of the location of the mobile device, although in order to minimize end-to-end latency, core network entities may preferably serve radio access network nodes which are geographically nearby. Moreover, a core network will typically provide the functionality by which connectivity external to the telecommunications network is obtained e.g. to the internet, or to the public switched telephone network (PSTN).

In operation, therefore, a given mobile device will obtain service via both a radio access network (for the management of radio connections) and a core network (e.g. for obtaining external connectivity).

In order to provide efficient use of core network resources, core network nodes may be grouped into pools; each pool serving a pre-configured group of radio access nodes, for example according to a load-balancing algorithm.

As described above, core network nodes generally perform functions which are not directly related to the exact location of a mobile device. In order to simplify implementation therefore, it is generally preferable that when a mobile device moves, such that its serving radio access node changes, its serving core network node does not change.

In order to identify mobile devices both for mobile-originated communications and for mobile-terminated communications while maintaining the privacy of the mobile device, either or both of the radio access network and the core network may assign temporary identifiers to the mobile terminal. These may differ in scope and as such be unique to varying degrees. For example, a core network may assign a globally unique identifier to a mobile terminal, while a radio access network may assign an identifier which is unique only within a limited geographic scope.

A core network node may include its own identity (or the identity of a group or ‘pool’ of core network nodes to which it belongs) in an identity which it assigns to a mobile device. When a mobile device connects to a new radio access node then, by providing the radio access node its core network identifier as part of a connection setup procedure, the radio access node is able to establish a connection to the same core network node or pool (i.e. the core network node from which the identity was obtained). This is preferable to the radio access node establishing a connection to an arbitrary core network node, since this may require the subsequent transfer of the core network context associated with the mobile device from the old to new core network nodes.

In [3], this challenge was addressed in the context of the use of core network identifiers issued by a 2G/3G core network, when establishing a connection in a long term evolution (LTE) network, and vice versa.

As described above, as different generations of radio access networks have been standardised, the core network technology has developed. In particular, for packet switched services (that is, as distinct from circuit switched services available in 2G and 3G radio access networks) the general packet radio service (GPRS) core network is used for 2G (GPRS/Enhanced Data rates for Global Evolution (EDGE)) and 3G (universal mobile telecommunications system (UMTS)) radio access networks, while an enhanced packet core (EPC) network is used with 4G (LTE) radio access networks. Work is ongoing to develop a 5G core network for use with new radio (NR) or 5G radio access networks. It is, however, expected that LTE radio access networks will be able to connect to either (or both) EPC and 5G core networks.

There is, therefore, a need to ensure that radio access nodes are able to establish connections for mobile devices with appropriate core network nodes, in light of the various generations of technology (and combinations thereof) which may be deployed.

SUMMARY

The present disclosure can help address or mitigate at least some of the issues discussed above.

Respective aspects and features of the present disclosure are defined in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

