WO2017028755A1

WO2017028755A1 - Method and apparatus for device-to-device communications between different networks

Info

Publication number: WO2017028755A1
Application number: PCT/CN2016/094942
Authority: WO
Inventors: Qianxi Lu
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-08-14
Filing date: 2016-08-12
Publication date: 2017-02-23

Abstract

Embodiments of the present disclosure relate to a method for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator. The method is performed at a first network element in the first network and comprises: obtaining information on coordinated resources and enabling the first terminal device in the first network to communicate directly with the second terminal device in the second network according to the information on the coordinated resources. Embodiments of the present disclosure also relate to a method for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator. The method is performed at the first terminal device and comprises: obtaining information on coordinated resources and communicating directly with the second terminal device according to the information on the coordinated resources. Embodiments of the present disclosure further relate to a corresponding apparatus, and computer program product.

Description

METHOD AND APPARATUS FOR DEVICE-TO-DEVICE COMMUNICATIONS BETWEEN DIFFERENT NETWORKS

TECHNICAL FIELD

The non-limiting and exemplary embodiments of the present disclosure generally relate to the technical field of wireless communications， and specifically to a method and apparatus for device-to-device communications between different networks， e.g. Public Land Mobile Networks (PLMNs) operated by different operators.

BACKGROUND

This section introduces aspects that may facilitate better understanding of the disclosure. Accordingly， the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

In the 3rd Generation Partnership Project (3GPP) Release 12 (Rel-12) ， the Long Term Evolution (LTE) standard has been extended with support of device-to-device (D2D) (specified as “sidelink” ) features targeting both commercial and public safety applications. Some applications enabled by Rel-12 relate to device discovery， where a device is able to sense proximity of another device and associated application by broadcasting and detecting discovery messages that carry device and application identities. Some other applications relate to direct communications based on physical channels terminated directly between devices.

One of potential extensions for the D2D work consists of support of Vehicle to X (V2X) communications， which includes any direct communications， such as vehicle-to -vehicle (V2V) ， vehicle-to-pedestrian (V2P) and vehicle-to-infrastructure/network (V2I/N) communications. V2X communications may take advantage of network infrastructures when they are available， however at least basic V2X connectivity should be possible even in the case of lack of coverage of the network. LTE-based V2X technology may enable tighter integration of communications with network infrastructures and V2X communications， as compared to using dedicated V2X technology. An LTE-based V2X interface may also be economically advantageous because of the economies of scale provided by LTE.

V2X communications may carry both non-safety and safety information， where each of applications and services may be associated with specific requirements， e.g.， in terms of latency， reliability， capacity， etc..

A study of the LTE-based V2X technology is urgently desired from market requirements. There are many research projects and field tests of connected vehicles in some countries or regions， such as United States， Europe， Japan， Korea and China. 3GPP Service and System Aspect Work Group 1 (SA1) meeting #69 recently agreed a new Rel-14 study on LTE support for V2X services to investigate use cases and requirements for the following：

V2V： covering LTE-based communications between vehicles.

V2P： covering LTE-based communications between a vehicle and a device carried by an individual， e.g. a handheld terminal carried by a pedestrian， cyclist， driver or passenger.

V2I/N： covering LTE-based communications between a vehicle and a roadside unit/network. A roadside unit (RSU) is a transportation infrastructure entity， e.g. an entity transmitting speed notifications， implemented in an eNodeB or a stationary user equipment (UE) .

The SA1 study considers both safety services and non-safety services and a possibility of using existing LTE technology for unicast/multicast/broadcast communications.

A Rel-13 Radio Access Network Study Item (RAN SI) is also approved to start， with an objective to evaluate new functionalities needed to operate LTE-based V2X (V2V， V2I/N， and V2P) ， and to investigate potential enhancements for vehicular services defined in 3GPP SA1 Technical Report 22.885.

At present， spectrum allocation for LTE-based V2X services turns into a primary problem for the further study of this topic. Generally， there would be two main solutions for the spectrum allocation：

1) allocating a spectrum in a service-specific way so as to allow multiple PLMNs operated by different operators sharing the spectrum for V2X service communications using a direct D2D-type interface， while cellular-type service communications still happen in a PLMN-specific licensed spectrum； and

2) allocating a dedicated spectrum to a third authority. For example， a dedicated spectrum is allocated to the First Responder Network Authority (First Net) in the United States for National Security and Public Safety (NSPS) services.

As for the above solution 2) ， the spectrum allocation is relatively simple， since it is limited within a PLMN operated by a same operator.

However， as for the above solution 1) ， which is more promising since its implementation may leverage the existing infrastructures， the spectrum allocation for the direct D2D-type communications between PLMNs operated by different operators is mainly contention-based. Thus， there may be a high possibility of collisions between the PLMNs.

SUMMARY

Various embodiments of the present disclosure aim at providing an efficient and effective solution to enable D2D-type communications between PLMNs operated by different operators based on the existing network infrastructures with a reduced collision probability or without a collision between the PLMNs. Other features and advantages of embodiments of the disclosure will also be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings， which illustrate the principles of embodiments of the present disclosure.

In a first aspect of the present disclosure， there is provided a method for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator. The method is performed at a network element in the first network. Particularly， the method comprises obtaining information on coordinated resources and enabling a first terminal device in the first network to communicate directly with a second terminal device in the second network according to the information on the coordinated resources.

In an embodiment that the first network element is located in a core network of the first network， the information on the coordinated resources may be obtained from at least one of the following： resource coordination with a second network element located in a core network of the second network； an application server； and a predetermined agreement on resource allocation between the first and second operators.

In another embodiment， the first network element may inform the first terminal device of the information on the coordinated resources so as to enable the first terminal device to communicate directly with the second terminal device.

In yet another embodiment， the first network element may inform a base station in an access network of the first network of the information on the coordinated resources and thereby the base station may schedule the first terminal device according to the information on the coordinated resources， such that the first terminal device may be enabled to communicate directly with the second terminal device.

In yet another embodiment， the base station may be informed of the information on the coordinated resources through one or more other network elements in the core network of the first network.

In a further embodiment， the base station may be informed of the information on the coordinated resources via an interface between the first network element and a mobility management entity， MME and an interface between the MME and the base station. Alternatively， the base station may be informed of the information on the coordinated resources via an interface between the first network element and a home subscriber server， HSS， an interface between the HSS and the MME， and the interface between the MME and the base station.

In an embodiment that the first network element is located in an access network of the first network， the information on the coordinated resources may be obtained from at least one of the following： a network element in a core network of the first network； a predetermined agreement on resource allocation between the first and second operators； detection of a usage condition of resources； and a measurement report of the first terminal device that indicates the usage condition of resources.

According to the first aspect of the present disclosure， the direct communications between terminal devices in different operator’s networks can be conducted according to the information on the coordinated resources. In other words， the method of the first aspect of the present disclosure enable device-to-device communications to be conducted based on coordination between networks rather than contention-based， so that the collision possibility between the different networks may be reduced or avoided.

In a second aspect of the present disclosure， there is provided a method for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator. The method is performed at the first terminal device. The method comprises obtaining information on coordinated resources and communicating directly with the second terminal device according to the information on the coordinated resources.

In an embodiment， the information on the coordinated resources may be obtained from at least one of the following： a network element in a core network of the first network； scheduling of a base station in an access network of the first network； and an application server.

In another embodiment， the method may further comprise measuring a usage condition of resources and reporting a measurement result to the base station in the access network. In this embodiment， the information on the coordinated resources may be obtained from the scheduling of the base station based on the measurement result.

According to the second aspect of the present disclosure， the direct communications between the first and second terminal devices in different operator’s networks can be conducted according to the information on the coordinated resources， which means this kind of device-to-device communications is based on coordination between networks rather than contention-based， so that the collision possibility between the different networks may be reduced or avoided.

In a third aspect of the present disclosure， there is provided an apparatus for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator. The apparatus is embodied at or as at least part of a network element in the first network. Particularly， the apparatus comprises an obtaining unit and a communications enabling unit. The obtaining unit is configured to obtain information on coordinated resources. The communications enabling unit is configured to enable a first terminal device in the first network to communicate directly with a second terminal device in the second network according to the information on the coordinated resources. The various embodiments of the first aspect may equivalently be applied to the third aspect.

In a fourth aspect of the present disclosure， there is provided an apparatus for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator. The apparatus is embodied at or as at least part of the first terminal device. Particularly， the apparatus comprises an obtaining unit and a communicating unit. The obtaining unit is configured to obtain information on coordinated resources. The communicating unit is configured to communicate directly with the second terminal device according to the information on the coordinated resources. The various embodiments of the second aspect may equivalently be applied to the fourth aspect.

In a fifth aspect of the present disclosure， there is provided an apparatus for device-to-device communications between a first network operated by a first operator and a second network operated by a second operator. The apparatus comprises a processor and a memory. The memory containing instructions executable by the processor， whereby the apparatus is operative to perform the method of the first aspect or the method of the second aspect.

In a sixth aspect of the present disclosure， there is provided an apparatus for device-to-device communications between a first network operated by a first operator and a second network operated by a second operator. The apparatus comprises processing means adapted to perform the method of the first aspect or the method of the second aspect.

In a seventh aspect of the present disclosure， there is provided a computer program product， comprising instructions which， when executed on at least one processor， cause the at least one processor to perform the method of the first aspect or the method of the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects， features， and benefits of various embodiments of the disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings， in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale， in which：

FIG. 1 shows a high level view of network architecture for providing proximity-based services according to 3GPP TS 23.303 V13.0.0；

FIG. 2 illustrates a flowchart of a method for facilitating direct communications between terminal devices located in networks operated by different operators according to embodiments of the present disclosure；

FIG. 3 illustrates a flowchart of a method for communications between terminal devices located in networks operated by different operators according to embodiments of the present disclosure；

FIG. 4 illustrates a schematic block diagram of an apparatus for facilitating communications between terminal devices located in networks operated by different operators according to embodiments of the present disclosure；

FIG. 5 illustrates a schematic block diagram of an apparatus for communications between terminal devices located in networks operated by different operators according to embodiments of the present disclosure； and

FIG. 6 illustrates a simplified block diagram of another apparatus for device-to-device communications between networks operated by different operators according to embodiments of the present disclosure.

DETAILED DESCRIPTION

Hereinafter， the principle and spirit of the present disclosure will be described with reference to the illustrative embodiments. It should be understood， all these embodiments are given merely for the skilled in the art to better understand and further practice the present disclosure， but not for limiting the scope of the present disclosure. For example， features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity， not all features of an actual implementation are described in this specification.

References in the specification to “an embodiment， ” “another embodiment， ” “yet another embodiment， ” etc.， indicate that the embodiment described may include a particular feature， structure， or characteristic， but every embodiment may not necessarily include the particular feature， structure， or characteristic. Moreover， when a particular feature， structure， or characteristic is described in connection with an embodiment， it is submitted that it is within the knowledge of one skilled in the art to affect such feature， structure， or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that， although the terms “first” and “second” etc. may be used herein to describe various elements， these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example， a first element could be termed a second element， and similarly， a second element could be termed a first element， without departing from the scope of example embodiments. As used herein， the term “and/or” includes any and all combinations of one or more of the associated listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit example embodiments. As used herein， the singular forms “a” ， “an” and “the” are intended to include the plural forms as well， unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” ， “comprising” ， “has” ， “having” ， “includes” and/or “including” ， when used herein， specify the presence of stated features， elements， and/or components etc.， but do not preclude the presence or addition of one or more other features， elements， components and/or combinations thereof.

In the following description and claims， unless defined otherwise， all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. For example， the term “base station” used herein may refer to e.g. Access Node (AN) ， eNB， eNodeB， NodeB， Base Transceiver Station (BTS) or Access Point and the like， depending on the technology and terminology used. Likewise， the term “terminal device” or UE used herein may refer to any terminal having wireless communications capabilities， including but not limited to， mobile phones， cellular phones， smart phones， or personal digital assistants (PDAs) ， portable computers， image capture devices such as digital cameras， gaming devices， music storage and playback appliances and any portable units or terminals that have wireless communications capabilities， or Internet appliances permitting wireless Internet access and browsing and the like. Hereafter， the terms “terminal device” and “UE” may be used interchangeably and the terms “base station” and “eNodeB” may be used interchangeably.

For better understanding of the present disclosure， a reference architecture model and some general concepts related to proximity-based services (ProSe) will be introduced first according to 3GPP Technical Specification (TS) 23.303 V13.0.0， which however will not constitute a limitation to the present disclosure.

FIG. 1 shows a high level view of network architecture for providing proximity-based services according to 3GPP TS 23.303 V13.0.0.

In FIG. 1， two PLMNs， i.e. PLMN A and PLMN B， operated by two different operators are illustrated. Each of the PLMNs may comprise a core network and at least one access network. As illustrated， the core network may comprise various network elements， for example， a Mobility Management Entity (MME) ， a Serving Gateway/Packet Data Network Gateway (S/PGW) ， a Home Subscriber Server (HSS) ， a Secure User Plane Location (SUPL) Location Platform (SLP) ， and a ProSe function (ProSe-F) . The access network may comprise an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) ， in which a base station， e.g. eNodeB， provides coverage for various UEs， including UE A or UE B. The UEs in this context are all ProSe-enabled. The ProSe-F is a logical function that is used for network related actions required for ProSe. Furthermore， the ProSe-F in the core network may interact with a ProSe Application Server， which hosts ProSe applications for the ProSe-enabled UEs. In FIG. 1， UE A uses a subscription ofPLMN A and UE B uses a subscription ofPLMN B.

In the illustrated architecture， interfaces between various network elements are labeled as reference points as follows：

PC1： The reference point between the ProSe application in the UE and the ProSe Application Server. PC1 is used to define application level signalling requirements.

PC2： The reference point between the ProSe Application Server and the ProSe-F. It is used to define interaction between the ProSe Application Server and ProSe functionality provided via the ProSe-F.

PC3： The reference point between the UE and the ProSe-F.

PC4a： The reference point between the HSS and ProSe-F.

PC4b： The reference point between the SLP and the ProSe-F.

PC5： The reference point between ProSe-enabled UEs used for control and user plane for ProSe direct discovery， ProSe direct communications and ProSe UE-to-Network Relay.

PC6： The reference point between ProSe Functions in different PLMNs or between the ProSe-F in a home PLMN and the ProSe-F in a Local PLMN.

S6a： The reference point between the HSS and the MME.

Furthermore， S 1 represents an interface between the eNodeB and the MME and LTE-Uu represents an interface between the UE and the eNodeB， on which radio protocols of E-UTRAN are running.

More detailed definitions and functionalities of these reference points or interfaces are defined in 3GPP standards， such as 3GPP TS 23.303 V13.0.0， which thus will not be repeated herein for the sake of brevity.

Hereafter， various embodiments of the present disclosure will be described in reference to FIGs. 2-4.

FIG. 2 illustrates a flowchart of a method 200 for facilitating direct communications between terminal devices located in respective networks operated by different operators according to embodiments of the present disclosure. The terminal devices include a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator. For example， the first and second networks may correspond respectively to PLMN A and PLMN B， and the first and second terminal devices may correspond respectively to UE A and UE B as illustrated in FIG. 1. Each of the first and second networks may comprise a core network and an access network. The method 200 may be implemented at a network element in the core network of the first network， e.g. the ProSe-F in PLMN A of FIG. 1. Alternatively， the method 200 may be implemented at a network element， i.e. a base station， in the access network of the first network， e.g. the eNodeB in E-UTRAN of PLMN A of FIG. 1. The alternative network elements will be collectively referred to as a first network element hereafter.

In FIG. 2， operations in blocks with a solid line are essential while operations in blocks with a broken line are optional depending on various embodiments of the present disclosure.

Particularly， the method 200 enters at block 210， in which information on coordinated resources (which is sometimes simplified as “coordination information” hereafter) is obtained at the first network element in the first network.

In a first embodiment that the first network element is located in the core network of the first network， e.g. the ProSe-F in PLMN A of FIG. 1， there are at least three options that the information on the coordinated resources may be obtained. The information on the coordinated resources used herein indicates resources， including time-frequency resources， which can be used by the first terminal device in the first network for direct communications with the second terminal device in the second network without a collision.

As a first option， the first network element in the first network may coordinate with a second network element in a core network of the second network so as to， for example， determine which resources can be used for direct communications between the terminal devices in the first and second networks without incurring a collision and/or which resources cannot be used for a possibility of incurring a collision， thereby obtaining the information on the coordinated resources. In this option， each of the first network element and the second network element is capable of acquiring a usage condition of resources for D2D-type communications， particularly for V2X communications， in the corresponding network， which makes the resource coordination possible. In an example using the network architecture as illustrated in FIG. 1， the first network element， i.e. the ProSe-F in PLMN A， may perform such coordination with the ProSe-F in PLMN B via an interface labelled as PC6.

As a second option， the first network element in the first network may obtain the information on the coordinated resources from an application server， which is located at a layer higher than the access layer of the first and second networks. The application server is capable of performing resource coordination between respective networks operated by different operators and thus acquiring a usage condition of resources in each network. Thereby， the application server may get knowledge of some information on which resources can be used for direct communications between the terminal devices in different networks without incurring a collision and/or which resources cannot be used for a possibility of incurring a collision. Accordingly， the application server may provide such information to the first network element， from which the coordination information may be obtained by the first network element. Alternatively， the application server may generate and provide the coordination information directly to the fire network element. In the example using the network architecture as illustrated in FIG. 1， the application server is the ProSe Application Server which may be a same network entity in both PLMN A and PLMN B. The first network element， i.e. the ProSe-F in PLMN A， may obtain such coordination information from the ProSe Application Server via an interface labelled as PC2.

As a third option， an agreement on resource allocation may be predetermined between different operators (e.g. the first and second operators) for example under government guidance or control. In this option， the first network element may obtain the coordination information based on the predetermined agreement.

The above three options of obtaining the coordination information may be used alone. However， it shall be appreciated that these options are not mutually exclusive. By contrast， two or more of the options may be combined together so as to more efficiently obtain the information on the coordinated resources. In this case， the first network element may take a comprehensive consideration of the information from various sources， such as the application server， the predetermined agreement， or the coordination with the second network element， thereby obtaining the information on the coordinated resources.

In a second embodiment that the first network element is located in the access network of the first network， e.g. the eNodeB in E-TRAN of FIG. 1， there are at least four options that the information on the coordinated resources may be obtained.

As a first option， the first network element may obtain the information on the coordinated resources from a network element in the core network of the first network. In the example using the network architecture as illustrated in FIG. 1， the first network element， i.e. the eNodeB in E-UTRAN， may obtain such coordination information from the ProSe-F via interfaces labelled as S1， S6a and PC4a. As for how the network element in the core network may obtain the information on the coordinated resources， it has been described according to the above three options and will not be repeated herein for the sake of brevity.

As a second option， the first network element in the access network may likewise obtain the information on the coordinated resources based on an agreement on resource allocation predetermined between different operators (i.e. the first and second operators) for example under government guidance or control as described above.

As a third option， the first network element in the access network itself may detect a usage condition of resources， particularly in the V2X spectrum for V2X communications， for example， by detecting which resources are used in other operator’s networks and which resources are available for its served terminal device， i.e. the first terminal device， to conduct direct communications with another terminal device， i.e. the second terminal device in the second network. Accordingly， the first network element may autonomously determine the information on the coordinated resources without relying on the coordination between core networks or the predetermined agreement.

As a fourth option， terminal devices， including the first terminal device， under coverage of the first network element in the access network may perform measurement on resource usage conditions of resources， particularly for V2X communications， and then report measurement results to the first network element. According to the reported measurement results， the first network element may get a knowledge of which resources can or cannot be used for the direct communications between terminal devices in different operator’s networks， thereby obtaining the information on the coordinated resources.

According to the third and fourth options， the first network element may obtain the information of the coordinated resources without involvement of the core network or assistance of the predetermined agreement， so that signaling overhead between the access network and the core network may be reduced. In this regard， the third and fourth options are preferably not used in combination of the first and second options. Even though， it shall be appreciated that the first and second options themselves may still be combined together to obtain the more accurate information on the coordinated resources， while the third and four options themselves may also be combined together to more efficiently obtain the information on the coordinated resources.

Now reference is made back to FIG. 2. The flow proceeds to block 220， in which the first terminal device in the first network is enabled to directly communicate with the second terminal device in the second network according to the information on the coordinated resources.

In the embodiment that the first network element is located in the core network， it may inform the first terminal device of the information on the coordinated resources at block 221， so as to enable the first terminal device to communicate directly with the second terminal device on the resources as indicted by that information. In the example using the network architecture as illustrated in FIG. 1， the first network element， i.e. the ProSe-F， may inform the UE A of the information on the coordinated resources via the interface labelled as PC3 in FIG. 1.

Alternatively， the first network element may inform the base station in the access network of the first network， which provides coverage for the first terminal device， of the information on the coordinated resources at block 222， so that the base station may schedule， according the information on the coordinated resources， the first terminal device to conduct direct communications with the second terminal device.

Particularly， the first network element may inform the base station through one or more other network elements in the core network of the first network， of the information on the coordinated resources. In the example using the network architecture as illustrated in FIG. 1， the first network element， i.e. the ProSe-F， may inform the eNodeB in E-UTRAN of the information on the coordinated resources via an interface labelled as PC4a between the ProSe-F and the HSS， an interface labelled as S6a between the HSS and the MME， and the interface labelled as S1 between the MME and the eNodeB. In particular， the information on the coordinated resources may be first written to the HSS by the ProSe-F and then read by the MME， which in turn forwards the information to the eNodeB.

Alternatively， the first network element， i.e. the ProSe-F， may inform the base station of the information on the coordinated resources via an interface (not shown in FIG. 1) between the first network element and the MME and the interface labelled as S1 between the MME and the base station. In this case， a direct interface between the ProSe-F and the MME is used bypassing the HSS， which enables a quicker response to the ProSe-F or the ProSe Application Server.

FIG. 3 illustrates a flowchart of a method 300 for conducting direct communications between a first terminal device and a second terminal device located respectively in a first network operated by a first operator and a second network operated by a second operator， according to embodiments of the present disclosure. For example， the first and second networks may correspond respectively to PLMN A and PLMN B， and the first and second terminal devices may correspond respectively to UE A and UE B as illustrated in FIG. 1. Each of the first and second networks may comprise a core network and an access network. The method 300 is implemented at the first terminal device in the first network， e.g. UE A in PLMN A of FIG. 1.

In FIG. 3， operations in blocks with a solid line are essential while operations in blocks with a broken line are optional depending on various embodiments of the present disclosure. The description will be started from the essential operation in block 310.

As illustrated， the method 300 enters at block 310， in which the first terminal device obtains information on coordinated resources. Then at block 320， the first terminal device conducts direct communications with the second terminal device according to the information on the coordinated resources.

In an embodiment， the first terminal device may obtain the information on the coordinated resources from a network element in the core network of the first network. In the example using the network architecture as illustrated in FIG. 1， the first terminal device， i.e. UE A may obtain this information from the ProSe-F in PLMN A via the interface labelled as PC3. Various embodiments of the method for obtaining and informing the information by the network element in the core network have been detailed above in relation to method 200 and with reference to FIG. 2， and thus will be omitted herein for the sake of brevity.

In another embodiment， the first terminal device may obtain the information on the coordinated resources from an application server， which is located at a layer higher than the access layer of the first and second networks. In the example using the network architecture as illustrated in FIG. 1， the first terminal device， i.e. UE A may obtain this information from the ProSe Application Server via the interface labelled as PC 1. Various embodiments of the method for obtaining and informing the information by the application server have been detailed above in relation to method 200 and with reference to FIG. 2， and thus will be omitted herein for the sake of brevity.

According to the above two embodiments， even in the case that the coverage of the base station in the access network is not available， the D2D connectivity between the first and second terminal devices may also be established on the coordinated resources without a collision. It shall be appreciated that the above embodiments may be implemented alone or together.

In yet another embodiment， the first terminal device may get knowledge of the information on the coordinated resources， including time-frequency resources， from scheduling of the base station in the access network of the first network. In the example using the network architecture as shown in FIG. 1， the first terminal device， i.e. UE A in PLMN A， may be scheduled by the base station， i.e. the eNodeB in E-UTRAN， according to the information on the coordinated resources obtained by the base station itself， to conduct direct communications with the second terminal device， UE B in PLMN B. Through this scheduling and further usage of the resources， the first terminal device may get to know the information regarding the coordinated resources.

In a further embodiment， the first terminal device may measure at block 301 a usage condition of resources， particularly in the V2X spectrum for V2X communications， and report at block 302 a result of the measurement to the base station， e.g. in the form of Received Signal Strength Indication (RSSI) . According to the reported measurement results from the first terminal device and other terminal devices under coverage of the base station， the base station may determine the overall usage condition of the resources in the V2X spectrum， thereby obtain information on which resources can or cannot be used for the first terminal device to conduct direct communications with the second terminal device. According to this， the base station may schedule the first terminal device to conduct the direct communications with the second terminal device.

It shall be appreciated that although the first terminal device conducts direct communications with the second terminal device according to the information the coordinated resources， it does not mean the first terminal device must only use the resources allocated to it by that coordination information； instead， the first terminal device may give priority in use of the resources indicated by the coordination information but may be allowed to use other resources with a certain percentage， which may be allocated to another terminal device in the second network， e.g. when the load on the first terminal device is high.

FIG. 4 illustrates a schematic block diagram of an apparatus 400 for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator， according to embodiments of the present disclosure. For example， the first and second networks may correspond to PLMN A and PLMN B， and the first and second terminal devices may correspond to UE A and UE B as illustrated in FIG. 1. Each of the first and second networks may comprise a core network and an access network. The apparatus 400 may be embodied at or as at least part of the first network element in the core network of the first network， e.g. the ProSe-F in PLMN A of FIG. 1. Alternatively， the apparatus 400 may be embodied at or as at least part of a network element， i.e. a base station， in the access network of the first network， e.g. the eNodeB in E-UTRAN of PLMAN A of FIG. 1.

Particularly， the apparatus comprises an obtaining unit 410 and a communications enabling unit 420. The obtaining unit 410 is configured to obtain information on coordinated resources. The communications enabling unit 420 is configured to enable a first terminal device in the first network to communicate directly with a second terminal device in the second network according to the information on the coordinated resources.

In an embodiment that the first network element is located in the core network of the first network， the obtaining unit 410 may be configured to obtain the information on the coordinated resources from at least one of the following： resource coordination with a second network element located in a core network of the second network； an application server； and a predetermined agreement on resource allocation between the first and second operators.

In another embodiment， the communications enabling unit 420 may be configured to inform the first terminal device of the information on the coordinated resources.

In yet another embodiment， the communications enabling unit 420 may be configured to inform the base station in the access network of the first network of the information on the coordinated resources. In this embodiment， the first terminal device is scheduled by the base station according to the information on the coordinated resources.

In a further embodiment， the communications enabling unit 420 may be further configured to inform the base station， through one or more other network elements in the core network， of the information on the coordinated resources. In particular， the communications enabling unit 420 may be configured to inform the base station of the information on the coordinated resources via an interface between the first network element and a mobility management entity， MME and an interface between the MME and the base station； or to inform the base station of the information on the coordinated resources via an interface between the first network element and a home subscriber server， HSS， an interface between the HSS and the MME， and the interface between the MME and the base station.

In an embodiment that the first network element is located in the access network of the first network， the obtaining unit 410 may be configured to obtain the information on the coordinated resources from at least one of the following： a network element in the core network of the first network； a predetermined agreement on resource allocation between the first and second operators； detection of a usage condition of resources； and a measurement report of the first terminal device that indicates the usage condition of resources.

The above units 410-420 may be configured to implement the corresponding operations or steps as described above in relation to the method 200 and thus will not be detailed herein for the sake of brevity.

FIG. 5 illustrates a schematic block diagram of an apparatus 500 for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator， according to embodiments of the present disclosure. For example， the first and second networks may correspond respectively to PLMN A and PLMN B and the first and second terminal devices may correspond respectively to UE A and UE B as illustrated in FIG. 1. Each of the first and second networks may comprise a core network and an access network. The apparatus 500 may be embodied at or as at least part of the first terminal device， e.g. UE A in PLMN A of FIG. 1.

Particularly， the apparatus 500 comprises an obtaining unit 510 and a communicating unit 520. The obtaining unit 510 is configured to obtain information on coordinated resources. The communicating unit 520 is configured to communicate directly with the second terminal device according to the information on the coordinated resources.

In an embodiment， the obtaining unit 510 may be configured to obtain the information on the coordinated resources from at least one of the following： a network element in a core network of the first network； scheduling of a base station in an access network of the first network； and an application server.

In a further embodiment， the apparatus 500 may further comprise a measuring unit 501 configured to measure a usage condition of resources and a reporting unit 502 configured to report a measurement result to the base station in the access network. In this embodiment， the information on the coordinated resources may be obtained by the obtaining unit 510 from the scheduling of the base station based on the measurement result.

In FIG. 5， various units in blocks with a solid line are essential while units in blocks with a broken line are optional depending on various implementations of the present disclosure.

The

above units

501， 502， 510 and 520 may be configured to implement the corresponding operations or steps as described above in relation to the method 300 and thus will not be detailed herein for the sake of brevity.

FIG. 6 illustrates a simplified block diagram of an apparatus 600 for device-to-device communications between a first network operated by a first operator and a second network operated by a second operator， according to embodiments of the present disclosure. The apparatus 600 may be embodied at or as at least part of a network element in a core network or a base station in an access network of the first network， e.g. ProSe-F in PLMN A or eNodeB in E-UTRAN of FIG. 1. Alternatively， the apparatus 600 may be embodied at or as at least part of the first terminal device， e.g. UE A in PLMN A of FIG. 1.

Particularly， the apparatus 600 comprises at least one processor 610， such as a data processor (DP) and at least one memory (MEM) 620 coupled to the processor 610. The apparatus 600 may further comprise a transmitter TX and receiver RX 630 coupled to the processor 610 for establishing communications with other apparatuses. The MEM 620 stores a program (PROG) 640. The PROG 640 may include instructions that， when executed on the associated processor 610， enable the apparatus 600 to operate in accordance with the embodiments of the present disclosure， for example to perform the method 200 when the apparatus 600 is embodied at or as at least part of the network element in the core network or the base station in the access network of the first network， or to perform the method 300 when the apparatus 600 is embodied at or as at least part of the first terminal device.

A combination of the at least one processor 610 and the at least one MEM 620 may form processing means 650 that is adapted to implement the embodiments of the present disclosure， for example to implement the method 200 when the apparatus 600 is embodied at or as at least part of the network element in the core network or the base station in the access network of the first network， or to implement the method 300 when the apparatus 600 is embodied at or as at least part of the first terminal device.

The MEM 620 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology， such as semiconductor based memory devices， magnetic memory devices and systems， optical memory devices and systems， fixed memory and removable memory， as non-limiting examples.

The processors 610 may be of any type suitable to the local technical environment， and may include one or more of general purpose computers， special purpose computers， microprocessors， digital signal processors (DSPs) and processors based on multicore processor architecture， as non-limiting examples.

Further， the present disclosure may also provide a computer program product comprising instructions that when executed by at least one processor， cause the at least one processor to perform the

method

200 or 300.

In addition， the present disclosure may also provide a carrier containing the computer program as mentioned above， wherein the carrier is one of an electronic signal， optical signal， radio signal， or computer readable storage medium. The computer readable storage medium can be， for example， an optical compact disk or an electronic memory device like a RAM (random access memory) ， a ROM (read only memory) ， Flash memory， magnetic tape， CD-ROM， DVD， Blue-ray disc and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means， but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function， or means that may be configured to perform two or more functions. For example， these techniques may be implemented in hardware (one or more apparatuses) ， firmware (one or more apparatuses) ， software (one or more modules) ， or combinations thereof. For a firmware or software， implementation may be made through modules (e.g.， procedures， functions， and so on) that perform the functions described herein.

Exemplary embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations， and combinations of blocks in the block diagrams and flowchart illustrations， respectively， can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer， special purpose computer， or other programmable data processing apparatus to produce a machine， such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

While this specification contains many specific implementation details， these should not be construed as limitations on the scope of any implementation or of what may be claimed， but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely， various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover， although features may be described above as acting in certain combinations and even initially claimed as such， one or more features from a claimed combination can in some cases be excised from the combination， and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that， as the technology advances， the inventive concept can be implemented in various ways. The above described embodiments are given for describing rather than limiting the disclosure， and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the disclosure as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The protection scope of the disclosure is defined by the accompanying claims.

Claims

A method (200) for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator， the method comprising：

obtaining (210) ， at a first network element in the first network， information on coordinated resources； and

enabling (220) the first terminal device in the first network to communicate directly with the second terminal device in the second network according to the information on the coordinated resources.
The method according to Claim 1， wherein the first network element is located in a core network of the first network， and

the information on the coordinated resources is obtained from at least one of：

resource coordination with a second network element located in a core network of the second network；

an application server； and

a predetermined agreement on resource allocation between the first and second operators.
The method according to Claim 2， wherein enabling the first terminal device to communicate directly with the second terminal device comprises：

informing (221) the first terminal device of the information on the coordinated resources.
The method according to Claim 2， wherein enabling the first terminal device to communicate directly with the second terminal device comprises：

informing (222) a base station in an access network of the first network of the information on the coordinated resources， wherein

the first terminal device is scheduled by the base station according to the information on the coordinated resources.
The method according to Claim 4， wherein informing the base station of the information on the coordinated resources comprises：

informing the base station， through one or more other network elements in the core network， of the information on the coordinated resources.
The method according to Claim 5， wherein informing the base station， through the one or more other network elements， of the information on the coordinated resources is implemented by：

informing the base station of the information on the coordinated resources via an interface between the first network element and a mobility management entity， MME and an interface between the MME and the base station； or

informing the base station of the information on the coordinated resources via an interface between the first network element and a home subscriber server， HSS， an interface between the HSS and the MME， and the interface between the MME and the base station.
The method according to Claim 1， wherein the first network element is located in an access network of the first network， and

wherein the information on the coordinated resources is obtained from at least one of：

a network element in a core network of the first network；

a predetermined agreement on resource allocation between the first and second operators；

detection of a usage condition of resources； and

a measurement report of the first terminal device that indicates the usage condition of resources.
A method (300) for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator， the method comprising：

obtaining (310) ， at the first terminal device， information on coordinated resources； and

communicating (320) directly with the second terminal device according to the information on the coordinated resources.
The method according to Claim 8， wherein

the information on the coordinated resources is obtained from at least one of：

a network element in a core network of the first network；

scheduling of a base station in an access network of the first network； and

an application server.
The method according to Claim 9， further comprising：

measuring (301) a usage condition of resources； and

reporting (302) a measurement result to the base station in the access network， wherein

the information on the coordinated resources is obtained from the scheduling of the base station based on the measurement result.
An apparatus (400) for facilitating communications between a first terminal device in a first network operated by a first operator and a second terminal device in a second network operated by a second operator， the apparatus comprising：

an obtaining unit (410) configured to obtain， at a first network element in the first network， information on coordinated resources； and

a communications enabling unit (420) configured to enable the first terminal device in the first network to communicate directly with the second terminal device in the second network according to the information on the coordinated resources.
The apparatus according to Claim 11， wherein the first network element is located in a core network of the first network， and

the obtaining unit is configured to obtain the information on the coordinated resources from at least one of：

resource coordination with a second network element located in a core network of the second network；

an application server； and

a predetermined agreement on resource allocation between the first and second operators.
The apparatus according to Claim 12， wherein the communications enabling unit is configured to：

inform the first terminal device of the information on the coordinated resources.
The apparatus according to Claim 12， wherein the communications enabling unit is configured to：

inform a base station in an access network of the first network of the information on the coordinated resources， wherein

the first terminal device is scheduled by the base station according to the information on the coordinated resources.
The apparatus according to Claim 14， wherein the communications enabling unit is further configured to：

inform the base station， through one or more other network elements in the core network， of the information on the coordinated resources.
The apparatus according to Claim 15， wherein the communications enabling unit is further configured to：

inform the base station of the information on the coordinated resources via an interface between the first network element and a mobility management entity， MME and an interface between the MME and the base station； or

inform the base station of the information on the coordinated resources via an interface between the first network element and a home subscriber server， HSS， an interface between the HSS and the MME， and the interface between the MME and the base station.
The apparatus according to Claim 11， wherein the first network element is located in an access network of the first network， and

wherein the obtaining unit is configured to obtain the information on the coordinated resources from at least one of：

a network element in a core network of the first network；

a predetermined agreement on resource allocation between the first and second operators；

detection of a usage condition of resources； and

a measurement report of the first terminal device that indicates the usage condition of resources.
An apparatus (500) for a first terminal device in a first network operated by a first operator to communicate with a second terminal device in a second network operated by a second operator， the apparatus comprising：

an obtaining unit (510) configured to obtain， at the first terminal device， information on coordinated resources； and

a communicating unit (520) configured to communicate directly with the second terminal device according to the information on the coordinated resources.
The apparatus according to Claim 18， wherein

the obtaining unit (510) is configured to obtain the information on the coordinated resources from at least one of：

a network element in a core network of the first network；

scheduling of a base station in an access network of the first network； and

an application server.
The apparatus according to Claim 19， further comprising：

a measuring unit (501) configured to measure a usage condition of resources； and

a reporting unit (502) configured to report a measurement result to the base station in the access network， wherein

the information on the coordinated resources is obtained by the obtaining unit from the scheduling of the base station based on the measurement result.
An apparatus (600) for device-to-device communications between a first network operated by a first operator and a second network operated by a second operator， the apparatus comprising a processor (610) and a memory (620) ， said memory containing instructions executable by said processor， whereby said apparatus is operative to perform the method of any of Claims 1-7 or the method of any of Claims 8-10.
An apparatus (600) for device-to-device communications between a first network operated by a first operator and a second network operated by a second operator， the apparatus comprising processing means (650) adapted to perform the method of any of Claims 1-7 or the method of any of Claims 8-10.
A computer program product (640) ， comprising instructions which， when executed on at least one processor， cause the at least one processor to perform the method of any of Claims 1-7 or the method of any of Claims 8-10.