NETWORKS

TECHNICAL FIELD

The present disclosure relates to techniques for sharing a communication device, in particular a relay node (RN) or a small cell, between at least one first network and at least one second network, e.g. at least one first network operated by a first operator, for example a Local Operator, and at least one second network operated by a second operator, for example a Visited Operator. In particular, the present disclosure relates to techniques for dynamic Radio Access Network (RAN) sharing in a multi-operator environment.

BACKGROUND

Fifth generation (5G) networks are expected to have increased coverage and capacity requirements, varying in terms of time. One potential solution to this problem is the dynamic densification of the network. This may be achieved using static or moving relays, unplanned small cells, which however need to be operated or owned by the network operator or administrator and cannot be shared among the network operators. This implies that for every area the network operator has to have installed its own relays for handling potential bandwidth and/or service demands. A service demand can be categorized, for example, in terms of coverage or capacity needs. On the other hand the networks do not have all the time the same bandwidth requirements, thus facilitating the small cells, e.g., relays, to be inactive or idle for big amounts of time. In case of overlapping coverage regions of individual networks, (e.g., individual operators that cover the same regions) each individual network needs to have its own relays for covering the increased throughput requirements that may occur temporarily, which implies that the operators need to make extensive investments for temporal densification. Hence, there is a need for an efficient and flexible cooperation of these individual networks.

SUMMARY

It is the object of the invention to provide a flexible network concept for a mobile communication network, in particular a 5G mobile network, fulfilling the combined requirements of individual networks of different network operators. This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

The invention is based on the idea that the individual networks described above may enable sharing of the equipment (e.g., access nodes like small cells and relays) among them. This can facilitate substantial cost savings and reduce computational complexity.

Thus, the individual networks are enabled to share small cells, e.g., self-backhauled unplanned small cells and relays. Various embodiments hereinafter are described by taking a relay as an example. Nevertheless, the described mechanisms apply to small cells with wireless backhaul connection to the network, under which relays and unplanned small cells can be considered. The relays may be owned by the individual network operators or by other organizations which undertake the maintenance and deployment of the relays. The relays may also be fixed or moving, depending on the deployment scenario. A moving relay can be mounted on a vehicle which can serve in-vehicle users and/or out-vehicle users. The moving relay which particularly serves out-vehicle users when the vehicle is parked or slow moving is referred to a nomadic node or vehicular nomadic relay. The disclosure includes techniques for, after interactions (dynamic exchange of information) among individual networks (i.e., network operators, network slices, etc.) to enable them to force RN(s) or small cells to roam to other individual networks for covering the latter's coverage or capacity needs. The needs can be classified as service requirements and/or network requirements and/or slice requirements. Additionally, the disclosure presents techniques for configuring the operation of the RN(s)/small cells under the new individual network.

After the dynamic exchange of information among the individual networks, a Relay Node may be dynamically shared among them so as to cover coverage or capacity demands. This can be performed by forcing a Relay Node to roam to another operator.

The presented solution implies that the network operators may communicate and negotiate for the sharing of the equipment. Once this takes place the Relay Node will be forced by the operator that has deployed it to roam to the operator that has particular coverage or capacity requirements. The former, from now on will be called "Local Operator" and the latter will be called "Visited Operator". The Relay Node will then attach to the visited operator and will start operating according to the dictations of the visited operator as all the devices deployed by this operator.

The disclosed solution is to force a RN or a small cell to register to another network. The idea enables signaling reduction and reduction of the delay for the registration of a RN to a network. It is based on a unique signaling in the radio interface, which involves exchange of new messages. All the disclosed messages and entities are relevant to standardization. The devices, systems and methods described hereinafter are based on communication devices, e.g. Small Cells and Relay Nodes. Small Cells are low-power nodes whose transmit (Tx) power is typically lower than macro node and can take the form of Planned/Unplanned pico-cells, femto-cells and relays. Relaying is standardized in LTE (Long Term Evolution) Release 10 and is also part of the fifth generation (5G) new radio (NR) Standardization 3GPP TR 38.801 : "Study on new RAT; Radio Access Architecture and Interfaces (Release 14)".

The devices described herein may be implemented in wireless communication networks, in particular communication networks based on mobile communication standards such as LTE, in particular LTE-A and/or OFDM-based system and totally new systems/technologies so called 5G. The devices described herein may further be implemented in a mobile device (or mobile station or User Equipment (UE)), for example in the scenario of device-to-device (D2D) communication where one mobile device communicates with another mobile device. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives. D2D communications in cellular networks is defined as direct communication between two mobile devices or mobile users without traversing the Base Station (BS) or eNodeB or the core network. D2D communications is generally non-transparent to the cellular network and can occur on the cellular spectrum (i.e., inband) or unlicensed spectrum (i.e., outband). D2D communications can highly increase spectral efficiency, improve throughput, energy efficiency, delay, and fairness of the network. The transmission and reception devices described herein may be implemented in mobile devices communicating under D2D scenarios. However, the transmission and reception devices described herein may also be implemented in a base station (BS) or eNodeB.

The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio frequency lying in a range of about 3 kHz to 300 GHz. The frequency range may correspond to frequencies of alternating current electrical signals used to produce and detect radio waves. The devices described herein may include small cells and may use network slicing. Small cells and network slicing as described hereinafter are two key enablers of 5G, e.g. as described by Next Generation Mobile Networks (NGMN) Alliance: "5G White Paper", Feb. 2015 and it is very likely that they will be standardized for 5G RAN (radio access network) also known as NR (next radio) in 3GPP. Small-cells can improve coverage and/or capacity, e.g. as highlighted in Next Generation Mobile Networks (NGMN) Alliance: "5G White Paper", Feb. 2015. Furthermore, Network Slicing is a composition of network functions, specific function settings and associated resources and can have different impacts on radio access network (RAN) design. In RAN, various slice-based target KPIs can comprise, e.g., throughput / spectral efficiency for enhanced mobile broadband (eMBB) communications, high reliability and low latency for ultra-reliable and low latency communications (URLLC), and connection density for massive machine-type communications (mMTC). Slices may have different requirements in terms of throughput and latency, which necessitate enabling different operations for different types of traffic to meet certain KPIs.

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

DSC: Dynamic Small Cell

RN: Relay Node

NMS: Network Management System

OP-A, OP-B Operator A, Operator B

RAN: Radio Access Network

RRC: Radio Resource Control

MME: Mobility Management Entity

CN: Core Network

NR: New Radio KPI: Key Performance Indicator

D2D: Device-to-device

OFDM: Orthogonal Frequency Division Multiplex

DL: Downlink

UL: Uplink

BS: Base Station, eNodeB, eNB, gNB

UE: User Equipment, e.g. a mobile device or a machine-type communication device

5G: 5 ^th generation according to 3GPP standardization

LTE: Long Term Evolution

RF: Radio Frequency

MBB: Mobile BroadBand

eMBB: enhanced Mobile BroadBand

URLLC: Ultra-Reliable Low Latency Communications

MTC: Machine Type Communication

TX: Transmit

RX: Receive

OAM: Operation and maintenance According to a first aspect, the invention relates to a communication device, in particular a relay node (RN) or a small cell, sharable between at least one first network and at least one second network, the communication device comprising: a transceiver, configured to receive a force roam message from at least one first base station (BS) associated with the at least one first network, the force roam message forcing the communication device to attach via at least one second base station (BS) associated with the at least one second network to the at least one second network; and a processor, configured to generate an attach message responsive to receiving the force roam message and to transmit the attach message via the transceiver to the at least one second BS associated with the at least one second network, the attach message requesting the at least one second network to attach the communication device to the at least one second network.

Such a communication device can be shared between multiple networks. Thus, the individual networks are enabled to share small cells, e.g., self-backhauled unplanned small cells and relays providing an efficient and flexible communication.

In a first possible implementation form of the communication device according to the first aspect, the force roam message comprises first information elements including an identifier of the at least one second network and a duration of the attachment to the at least one second network.

This provides the advantage that the communication device can derive the at least one second network, e.g. the visited operator network, by exploring the force roam message. The identifier and the duration of attachment can be simply extracted from that information.

In a second possible implementation form of the communication device according to the first implementation form of the first aspect, the processor is configured to attach the communication device as a User Equipment (UE) during a first phase UE attach based on the first information elements of the force roam message.

This provides the advantage that the communication device can exploit the information from the force roam message to apply the existing mechanisms derived by the 3GPP standard TS 36.300 to attach as a UE to the second network and receive configuration information from the second network.

In a third possible implementation form of the communication device according to the second implementation form of the first aspect, the processor is configured to attach the communication device as a Relay Node (RN) during a second phase RN attach based on configuration information received from the at least one second network during the first phase UE attach. This provides the advantage that the communication device can use the configuration information received from the second network to attach as RN to the second network by exploiting the existing mechanisms derived by the 3GPP standard TS 36.300.

In a fourth possible implementation form of the communication device according to the first implementation form of the first aspect, the force roam message further comprises second information elements including at least one of the following: configuration information and network parameters of the at least one second network, in particular an identification of the at least one second BS, security information, initial access information for fast connection, in particular Random Access Channel (RACH) preambles.

This provides the advantage that the communication device can use these information elements to establish a fast and robust connection to the second network. In a fifth possible implementation form of the communication device according to the fourth implementation form of the first aspect, the processor is configured to attach the communication device as a Relay Node (RN) during a second phase RN attach based on the first and second information elements of the force roam message.

This provides the advantage that the communication device can receive the configuration of the second network from the second information elements and can avoid the first phase of attaching as a UE to receive configuration information from the second network. In a sixth possible implementation form of the communication device according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured to transmit a Relay Initial Attach message to the at least one first network before receiving the force roam message from the at least one first BS, the Relay Initial Attach message comprising an indicator of the communication device, in particular an RN indicator.

This provides the advantage that the communication device is known to the first network and the first network can provide the force roam message to the communication device by using its Relay Node Indicator as identification.

In a seventh possible implementation form of the communication device according to the sixth implementation form of the first aspect, the Relay Initial Attach message further comprises Slice Type Support information indicating a support of the communication device for specific logical network (Slice) functions.

This provides the advantage that the communication device can be applied to any kind of independent networks, including slices. Particularly the slices may belong to different operators. According to a second aspect, the invention relates to a network entity, in particular an operation and maintenance entity, of at least one second network, the network entity comprising: a processor, configured to generate a Relay Request message, the Relay Request message configured to request for a communication device, in particular a Relay Node (RN) or a small cell, which communication device is attached to at least one first network and is sharable with the at least one second network; and a transceiver, configured to transmit the Relay Request message to the at least one first network and configured to receive a Relay Offer message from the at least one first network, wherein the Relay Offer message comprises information about at least one communication device that is sharable with the at least one second network, in particular an RN indicator.

Such a network entity enables sharing of a communication device between multiple networks. Thus, the network entity enables the individual networks to share small cells, e.g., self-backhauled unplanned small cells and relays providing an efficient and flexible communication.

In a first possible implementation form of the network entity according to the second aspect, the Relay Request message comprises at least one of the following information elements: location, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern; and the Relay Offer message comprises at least one of the following information elements: RN indicator, cost, power availability, mobility patterns, management information.

This provides the advantage that the network entity can provide the first network with all information required for configuring the Relay Node enabling flexible and fast roaming.

In a second possible implementation form of the network entity according to the second aspect as such or according to the first implementation form of the second aspect, the processor is configured to generate a Relay Commit message based on the information of the Relay Offer message, wherein the Relay Commit message comprises information about at least one preferred communication device which the at least one second Network prefers to share with the at least one first network; and the transceiver is configured to transmit the Relay Commit message to the at least one first Network to which the at least one preferred communication device is attached to.

This provides the advantage that the second network can select a preferred communication device and inform the first network about its selection. Selection of the suitable roaming device is thus flexible and dynamic.

In a third possible implementation form of the network entity according to the second implementation form of the second aspect, the Relay Commit message comprises information about the at least one preferred communication device, in particular a Relay Node (RN) identifier of the at least one preferred communication device.

This provides the advantage that the Relay Node can be precisely and safely identified. In a fourth possible implementation form of the network entity according to the third implementation form of the second aspect, the Relay Commit message further comprises at least one of the following information elements: a duration of attaching the communication device to the at least one second network, configuration and security information for enabling the communication device to attach to the at least one second network.

This provides the advantage that the network entity can provide the configuration information to the communication device such that the communication device can avoid the first phase of attaching as a UE to receive configuration information from the second network.

In a fifth possible implementation form of the network entity according to the fourth implementation form of the second aspect, the processor is configured to initiate transmission of a force roam message via at least one base station (BS) associated with the at least one first network to the at least one preferred communication device, the force roam message forcing the at least one preferred communication device to attach via at least one second base station associated with the at least one second network to the at least one second network.

This provides the advantage that the network entity can trigger the roaming process to enable the communication device attach to the second network.

In a sixth possible implementation form of the network entity according to the second aspect as such or according to any of the preceding implementation forms of the second aspect, the transceiver is configured to receive an intermediate Relay Offer message from the at least one first network responsive to transmitting the Relay Request message if no communication device is attached to the at least one first network, the intermediate Relay Offer message indicating that no communication device is available.

This provides the advantage that the second network is informed about available or not available communication devices that may be applied for roaming for improving the roaming process. In a seventh possible implementation form of the network entity according to any of the first to the sixth implementation forms of the second aspect, the Relay Request message further comprises Slice Type Support information indicating a desired support of the communication device for specific logical network (Slice) functions.

This provides the advantage that the network entity can be applied to any kind of independent networks, including slices. Particularly the slices may belong to different operators.

According to a third aspect, the invention relates to a communication system supporting sharing of a communication device between at least one first network and at least one second network, in particular a Relay Node (RN) or a small cell, the communication system comprising: at least one second network with at least one network entity according to the second aspect as such or according to any of the implementation forms of the second aspect; at least one first network with at least one communication device according to the first aspect as such or according to any of the implementation forms of the first aspect, in particular a RN or a small cell, attached to the at least one first network, wherein the at least one second network is configured to interact with the at least one first network in order to roam the communication device from the at least one first network to the at least one second network. Such a communication system enables sharing of a communication device between multiple networks. Thus, the communication system enables the individual networks to share small cells, e.g., self-backhauled unplanned small cells and relays providing an efficient and flexible communication. According to a fourth aspect, the invention relates to a method for sharing a communication device, in particular a relay node (RN) or a small cell, between at least one first network and at least one second network, the method comprising: receiving, by the communication device, a force roam message from at least one first base station (BS) associated with the at least one first network, the force roam message forcing the communication device to attach via at least one second base station (BS) associated with the at least one second network to the at least one second network; generating an attach message responsive to receiving the force roam message, the attach message requesting the at least one second network to attach the communication device to the at least one second network; and transmitting the attach message to the at least one second BS associated with the at least one second network. Such a method enables sharing of communication devices between multiple networks. Thus, the method enables the individual networks to share small cells, e.g., self- backhauled unplanned small cells and relays providing an efficient and flexible communication.

According to a fifth aspect, the invention relates to methods for determining the relays/small cells (static or dynamic) that are based on a number of parameters such as: Location, Duration, Monetary cost, Slice Type Support, Slice requirements. The determined relays/small cells are then forced to roam and operate under the domain of the receiving PLMN. The determined relays/small cells may receive configuration information on how to operate under the receiving operation such as: Configuration of antennas, Backhaul configuration information, Type of relay/small cell they are going to operate as, Transmission power, Duration, Slice-specific Configurations. Inter-PLMN Information exchange may be based on the needed information elements above. According to a sixth aspect, the invention relates to the relay/small cell that performs the methods according to the fifth aspect. According to a seventh aspect, the invention relates to the system comprising the relay/small cell, gNBs, and the methods above.

Such methods enable sharing of communication devices between multiple networks providing an efficient and flexible communication.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a schematic diagram illustrating a standard procedure 100 for the attach of a Relay Node in a network according to 3GPP TS 36.300; Fig. 2 shows a schematic diagram of a communication system 200 including a first network 210 operated by a first operator (OP-A) and a second network 220 operated by a second operator (OP-B), where a communication device 800 is forced to roam from the first network 210 to the second network 220 during a first communication phase according to an implementation form; Fig. 3 shows a schematic diagram of the communication system 200 of Fig. 2 in a second communication phase when the communication device 800 is attached to the second network 220 according to an implementation form; Fig. 4 shows a message sequence diagram 400 illustrating an exemplary message exchange sequence where the operators exchange information for the RN configuration according to a first alternative implementation form;

Fig. 5 shows a message sequence diagram 500 illustrating an exemplary message exchange sequence where the operators do not exchange information for the RN configuration according to a second alternative implementation form;

Fig. 6 shows a message sequence diagram 600 illustrating an exemplary message exchange sequence where the operators exchange information for the RN configuration but the operators do not have registered RN according to a third alternative implementation form;

Fig. 7 shows a message sequence diagram 700 illustrating an exemplary message exchange sequence where slices belonging to different operators are used according to a fourth alternative implementation form;

Fig. 8 shows a block diagram of an exemplary communication device 800 according to an implementation form; Fig. 9 shows a block diagram of an exemplary network entity 900 according to an implementation form; and

Fig. 10 shows a schematic diagram illustrating an exemplary method 1000 for sharing a communication device between at least one first network and at least one second network according to an implementation form.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The temporal densification has been considered very important up to now as a paradigm enabling the networks to meet potential higher capacity demands and also providing an efficient (in terms of energy consumption, and cost) solution. 3GPP has defined the standard operation of the relays in TS 36.300 "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2". The devices, systems and methods described hereinafter may be attached to a network by using the standard procedure 100 for attaching a Relay Node in a network according to 3GPP TS 36.300 as illustrated in Fig. 1 .

The attachment of a Relay Node (RN) in the network comprises two phases 1 10, 130. In the first phase 1 10, when a Relay 101 is being turned on 107 initially performs the regular attach process 1 12 of a user equipment (UE) 1 1 1 , during which it is being authenticated and authorized to operate as relay. Afterwards, it receives from the Operation and Maintenance (OAM) function 106 of the network its initial configuration 1 13 and afterwards it detaches from the network 1 14. In the second phase 130, the Relay Node 101 attaches to the network 132 and receives the rest of the required configuration parameters 134 from the respective servers (e.g., Serving Gateway 104, Subscriber Server, in the LTE system. After attachment as relay 133 and configuration updates 135, 136, 137, 138 the RN starts to operate as a relay 139. The network may include RN 101 , eNB 102, MME 103, S/P-GW 104, HSS 105 and OAM 106 as shown in Fig. 1 .

However, the previous solution has the following disadvantages: It does not enable the individual network operator to share the operator's equipment; it does not enable the flexibility of on-demand sharing of a Relay Node to another network based on the network and/or service and/or slice requirements. The latter can be a very important enabler in the emerging paradigm called "network slice". A "network slice" is considered to be fully operational logical network containing all required protocols and network resources. In some deployments, network slices can be considered as completely individual networks which however belong to the same network operator. This gives to the network operator the ability to share resources among the network slices for meeting the respective slice demands.

Please note that even though that the disclosed concept is applicable to both sharing of equipment among operators and among slices the following description uses as an example the sharing of RNs among different operators. However the same principles may be applied to different slices. In some cases some particular examples for slices are provided as well.

Fig. 2 shows a schematic diagram of a communication system 200 including a first network 210 operated by a first operator (OP-A) and a second network 220 operated by a second operator (OP-B), where a communication device 800 is forced to roam from the first network 210 to the second network 220 during a first communication phase according to an implementation form. Fig. 3 shows the second communication phase when the communication device 800 is attached to the second network 220.

Note that although Figs. 2 and 3 depict only two networks 210, 220 associated to two different operators (OP-A and OP-B), the techniques described in this disclosure may be applied to a plurality of first (or also referred to as local) networks associated to a plurality of different (local) operators and a plurality of second (or also referred to as visited) networks associated to a plurality of different (visited) operators. Figs. 2 to 7 illustrate only two different operators and networks due to simplicity reasons. In Figs. 8 to 10 a more general description is presented using the terms "at least one first network" and "at least one second network". In the first communication phase depicted in Fig. 2, the communication device 800, e.g. a relay node (RN) may be associated to the first network 210. A network management system 221 of the second network 220 identifies coverage and capacity issues 201 and informs a network management system 21 1 of the first network 210 about identification 202 of a small cell to be used by other operators. The first network 210 sends a force roam message 203 via a first base station 212 to the communication device 800 in order to force the communication device 800 roaming to the second network 220. In Fig. 2, operator-A (OP-A) of first network 210 may be considered to be local operator and operator-B (OP-B) of second network 220 may be considered to be visited operator, for example. Note that there may be a plurality of first networks 210 and a plurality of second network 220 associated to different network operators. When an operator, in Fig. 2, OP-B, identifies that it has certain capacity/coverage needs

201 in the specific area that it may not cover using its infrastructure it will communicate

202 with the other operators in the specific region for identifying RN 800 that is available for being used for certain amount of time. Assume that in the specific region there is collocated another operator (OP-A in Fig. 2) who has in this area deployed a RN (indicated as RN, 800 in Fig. 2). This may be a preinstalled fixed RN, an unplanned small cell, a moving relay node, or any type of moving small cell (e.g., Nomadic Node, etc.). This RN 800 may be in use or idle. If the OP-A 210 decides to offer/share the RN 800 with OP-B 220 then it will send a Force Roam message 203 to the RN 800 and it will command the RN 800 to attach to OP-B 220. Then the RN 800 will attach 304 to OP-B 220 and receive the respective configuration from the OP-B 220 as shown in Fig. 3.

The previous process requires specific enhancements in the communication among the operators, the BSs and the RN(s); these particular enhancements will be described in details in the following sections.

As described above, a mechanism for enabling individual networks to share network nodes such as (moving or static) Relay Nodes (RN), small cells, etc. is presented. This process requires interaction among the network operators for forcing a RN or small cell to attach to another network. Please note that the following description focuses on the RNs but similar process can be applied in other type of nodes such as small cells, nomadic nodes, etc.

The following description presents alternative exemplary implementations for the forcing of a RN to roam from one network to another. Additional embodiments are provided for the case of the network slices (see Fig. 7).

Fig. 4 shows a message sequence diagram 400 illustrating an exemplary message exchange sequence where the operators exchange information for the RN configuration according to a first alternative implementation form.

Fig. 4 presents the first alternative implementation, where the network operators 210, 220 communicate directly and exchange information regarding the configuration that the RN 800 should have after it roams. In particular, as shown in the Fig. 4, once the Operation and Maintenance (OAM) function 421 of OP-B 220 identifies a coverage/capacity issue 401 it communicates directly with the OAM function 416 of the other operators in the respective region (in Fig. 4 it is OP-A 210, however it may be multiple other operators) and performs a certain request (RELAY REQ, 402) with a description of its particular requirements regarding its needs. The message will contain one or more of the following information fields 402b: location, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern, etc. The OAM functions of the other operators in the region will provide their offer based on their availability using a message (RELAY OFFER 403) containing at least one of the RN(s) identification number 403a, the cost, power availability, mobility patterns, management information 403b. Then the OP-B 220 will, if one of the offers that it receives meets its requirements, commit the use of the RN(s) using a RELAY COMMIT message 404, in which it will provide the information 404b regarding the IDs 403a of the RN(s) that it wants to commit, the duration that it wants to commit these nodes, and configuration and security information for enabling the RN to attach to the OP-B 220. The security information is required for the RN to attach and operate in the network of OP-B 220, whereas the RN configuration will also enable the RN 800 to skip the initial phase 1 10 of the RN attachment in the network as described above with respect to Fig. 1 , which requires that the RN 800 attaches in the network 1 1 1 as a UE at first, it receives its configuration 1 13 afterwards and then it detaches 1 14 and re-attaches 132 as a RN. Afterwards, the OAM 416 of the OP-A 210 will inform the BS 212 to which coverage is the RN 800 that it should send a Forced_Roaming message 405, 203 to the RN 800. The latter contains at least one of the following information fields, based on the previous message exchange between the operators: OP ID, duration of the lease 405a, configuration information 405b (donor BS from OP-B), and security information. Then the BS 212 will forward this Forced_Roaming message 405, 203 to the RN 800 which will use it for attaching directly 407 as a RN to OP-B, as described above with respect to Fig. 1 , e.g., the second phase 130 of the standard procedure. Fig. 5 shows a message sequence diagram 500 illustrating an exemplary message exchange sequence where the operators do not exchange information for the RN configuration according to a second alternative implementation form.

Fig. 5 presents a second alternative implementation, where the network operators 210, 220 interact for the lease of the RN 800 but without exchanging information regarding the future configuration of the RN 800. In particular, as shown in the Fig. 5, once the Operation and Maintenance (OAM) function 421 of OP-B 220 identifies a coverage/capacity issue 401 it communicates directly with the OAM function 416 of the other operators in the respective region (in Fig. 5 it is OP-A 210, however it may be multiple other operators) and performs a certain request (RELAY REQ 402) with a description of its particular requirements regarding its needs. The message it will contain one or more of the following information fields: location, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern, etc. The OAM functions of the other operators in the region will provide their offer based on their availability using a message (RELAY OFFER 403) containing at least one of the RN(s) identification number 403a, the cost, power availability, mobility patterns, management information. Then the OP-B 220 will, if one of the offers that it receives meets its requirements, commit the use of the RN(s) using a RELAY COMMIT message 404, in which it will provide the information regarding the IDs of the RN(s) 403a that it wants to commit, and the duration that it wants to commit these nodes. Afterwards, the OAM 416 of the OP-A 210 will inform the BS 212 to which coverage is the RN 800 that it should send a Forced_Roaming message 405, 203 to the RN 800; the same process applies for multiple BS and RNs. The latter contains at least one of the following information fields 405a, based on the previous message exchange between the operators: OP ID, and duration of the lease. Then the BS 212 will forward this Forced_Roaming message 405, 203 to the RN 800 which will use it for attaching 507 to OP-B 220, e.g., following the standard procedure as described above with respect to Fig. 1 .

Fig. 6 shows a message sequence diagram 600 illustrating an exemplary message exchange sequence where the operators exchange information for the RN configuration but the operators do not have registered RN according to a third alternative implementation form.

Fig. 6 presents a third alternative implementation, where the network operators communicate directly and exchange information regarding the configuration that the RN should have after it roams. In particular, as shown in the Fig. 6, once the Operation and Maintenance (OAM) function 421 of OP-B 220 identifies a coverage/capacity issue 401 it communicates directly with the OAM function 416 of the other operators in the respective region (in Fig. 6 it is OP-A 210, however it may be multiple other operators) and performs a certain request (RELAY REQ 402) with a description of its particular requirements regarding its needs. The message contains one or more of the following information fields: location, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern, etc. In the presented sequence none of the operators has an available RN 800 to offer and thus replying the unavailability 403b of RN or the available RNs do not fulfill the requirements of the visited operator, here PLMN-B (i.e., OP-B, 220). Then at certain point of time a RN 800 attaches to the network of one of the operators (i.e., OP-A 210) and it performs the initial attachment process 605 (e.g., Phase 1 , 1 10 as described above with respect to Fig. 1 ) with the RN indicator 605a. By means of the RN indicator 605a, PLMN-A (i.e., OP-A, 210) can be informed by messages 605, 606 about the RN functionality already in the first phase of the attachment. Then the negotiation process takes place between the operators 210, 220. In particular, The OAM function 416 of OP-A 210 will provide his offer based on the availability using a message (RELAY OFFER 403) containing at least one of the RN(s) identification number, the cost, power availability, mobility patterns, management information. Then the OP-B 220 will, if one of the offers that it receives meets its requirements, commit the use of the RN(s) 800 using a RELAY COMMIT message 404, in which it will provide the information regarding the IDs of the RN(s) 800 that it wants to commit, the duration that it wants to commit these nodes, and configuration and security information for enabling the RN 800 to attach to the OP-B 220. The security information is required for the RN 800 to attach and operate in the network 220 of OP-B, whereas the RN configuration will also enable the RN 800 to skip the initial phase 1 10 of the RN attachment in the network (described above with respect to Fig. 1 ), which requires that the RN 800 attaches in the network as a UE at first 1 1 1 , it receives its configuration 1 13 afterwards and then it detaches 1 14 and re-attaches as a RN 132. Afterwards, the OAM 416 of the OP-A 210 will inform the BS 212 to which coverage is the RN 800 that it should send a Forced_Roaming message 405, 203 to the RN 800. The latter contains at least one of the following information fields, based on the previous message exchange between the operators: OP ID, Duration of the lease, configuration information (donor BS from OP-B), and security information. Then the BS 212 will forward this Forced_Roaming message 405, 203 to the RN 800 which will use it for attaching directly 610 as a RN to OP-B 220, as described above.

Fig. 7 shows a message sequence diagram 700 illustrating an exemplary message exchange sequence where slices belonging to different operators are used according to a fourth alternative implementation form.

The techniques described in this disclosure may also be applied in any type of independent networks, including slices 71 1 , 721 . In a particular implementation, when the slices 71 1 , 721 belong to different operators 210, 220 some updates are required. Fig. 7 provides the messages exchange for this particular implementation. For instance, in the initial attachment 704 of the RN 800, RN indicator 605a and slice-type (or slice or slice RAN configuration) support 605b can be communicated to OP-A 210. In details, once the core network functions (e.g., the mobility function of a slice, the OAM of a slice, or any similar function that undertakes these processes) of one slice instance 721 identifies the need of additional resources 701 (in case of coverage/capacity needs) it will communicate 702 with the OAM function 421 of the network operator (i.e., OP-B 220 in Fig. 7) and it will require additional resources. Then, in case of unavailable resources 703, the OAM 421 of OP-B 220 will proceed in direct communication with the OAM functions 416 of the other operators in the respective region (in Fig. 7 it is OP-A 210) and will perform a certain request (RELAY REQ 402) with a description of its particular requirements regarding its needs. The message will contain one or more of the following information fields: location, slice ID or slice type 402c, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern, etc. The OAM function 416 of the other operators (i.e., OP-A 210 in Fig. 7) will communicate with the core network functions of the slices that are operational requesting for underutilized RNs in the respective region/location. Once available RNs 800 are identified the negotiation process takes place between the operators 210, 220. In particular, the OAM function 416 of OP-A 210 will provide his offer based on the availability using a message (RELAY OFFER 403) containing at least one of the RN(s) identification number 708, the cost, power availability, mobility patterns, management information. Then the OP-B 220 will if one of the offers that it receives meets its requirements commit the use of the RN(s) using a RELAY COMMIT message 404, in which it will provide the information regarding the IDs of the RN(s) that it wants to commit, the duration that it wants to commit these nodes, and configuration and security information for enabling the RN 800 to attach to the OP-B 220. The security information is required for the RN 800 to attach and operate in the network 220 of OP-B, whereas the RN configuration will also enable the RN 800 to skip the initial phase of the RN attachment in the network, which according to the description with respect to Fig. 1 requires that the RN attaches 1 1 1 in the network as a UE at first, it receives its configuration 1 13 afterwards and then it detaches 1 14 and re-attaches 132 as a RN. Afterwards, the OAM 416 of the OP-A 210 will forward this information to the core network functions of the slice that it will offer the RN 800 and the latter will forward to the core network functions of the slice of OP-B 220 that requests the resources the RN ID and additional information required for admitting the RN 800 once it attaches to the slice. Additionally, the OAM 416 of OP-A 210 will inform the BS 212 to which coverage is the RN that it should send a Forced_Roaming message 405, 203 to the RN. The latter contains at least one of the following information fields, based on the previous message exchange between the operators: OP ID, Duration of the lease, configuration information (donor BS from OP-B), and security information. Then the BS 212 will forward this Forced_Roaming message 405, 203 to the RN 800 which will use it for attaching directly 715 as a RN to OP-B, as described above with respect to Fig. 1 .

In one alternative implementation, the network operators interact for the lease of the RN but without exchanging information regarding the future configuration of the RN. In this case the RN will have to perform regular attach, e.g., as described above with respect to Fig. 1 .

It is to be noted that part of the described implementation aspects of above embodiments can be straightforwardly combined. For example, the RN indicator and slice type support as mentioned with respect to Fig. 7 can be performed in the Phase II 130 of RN attach procedure as described with respect to Fig. 1 . Besides, the two-phase attach procedure can also be applied in the embodiment described with respect to Fig. 7. Furthermore, such different combinations of the mechanisms can be determined based on the target design criteria, such as, latency reduction and/or signaling reduction and/or complexity implication.

Fig. 8 shows a block diagram of an exemplary communication device 800 according to an implementation form. The communication device 800 may be a RN or a small cell as described above with respect to Figs. 2 to 7. The communication device 800 is sharable between at least one first network, e.g. a network 210 of a first operator OP-A as described above with respect to Figs. 2 to 7, and at least one second network, e.g. a network 220 of a second operator OP-B as described above with respect to Figs. 2 to 7. The communication device 800 includes a transceiver 801 and a processor 803. The transceiver 801 is configured to receive a force roam message, e.g. a force roam message 203 as described above with respect to Figs. 2 to 7, from at least one first base station (BS) 212 associated with the at least one first network 210. The force roam message 203 forces the communication device 800 to attach via at least one second base station 222 associated with the at least one second network 220 to the at least one second network 220, e.g. as described above with respect to Figs. 2 to 7.

The processor 803 is configured to generate an attach message, e.g. an attach message 304 as described above with respect to Figs. 2 to 7, responsive to receiving the force roam message 203 and to transmit the attach message 304 via the transceiver 801 to the at least one second BS 222 associated with the at least one second network 220. The attach message 304 requests the at least one second network 220 to attach the communication device 800 to the at least one second network 220, e.g. as described above with respect to Figs. 2 to 7.

The force roam message 203, 405 may include first information elements 405a including an identifier of the at least one second network 220 and a duration of the attachment to the at least one second network 220, e.g. as described above with respect to Figs. 2 to 7.

The processor 803 may be configured to attach the communication device 800 as a User Equipment UE during a first phase UE attach 1 10, 1 1 1 based on the first information elements 405a of the force roam message 203, 405, e.g. as described above with respect to Figs. 1 to 7.

The processor 803 may be configured to attach the communication device 800 as a Relay Node (RN) during a second phase RN attach 130, 132 based on configuration information 1 13 received from the at least one second network 220 during the first phase UE attach 1 10, 1 1 1 , e.g as described above with respect to Figs. 1 to 7.

The force roam message 203, 405 may further include second information elements 405b including at least one of the following: configuration information and network parameters of the at least one second network 220, in particular an identification of the at least one second BS 222, security information, initial access information for fast connection, in particular Random Access Channel (RACH) preambles, e.g. as described above with respect to Figs. 2 to 7. The processor 803 may be configured to attach the communication device 800 as a Relay Node (RN) during a second phase RN attach 130, 132 based on the first and second information elements 405a, 405b of the force roam message 203, 405, e.g. as described above with respect to Figs. 1 to 7. The processor 803 may be configured to transmit a Relay Initial Attach message 605 to the at least one first network 210 before receiving the force roam message 203, 405 from the at least one first BS 212. The Relay Initial Attach message 605 may include an indicator 605a of the communication device 800, in particular an RN indicator, e.g. as described above with respect to Figs. 2 to 7. The Relay Initial Attach message 605 may further include Slice Type Support information 605b indicating a support of the communication device 800 for specific logical network (Slice) functions, e.g. as described above with respect to Figs. 2 to 7. Fig. 9 shows a block diagram of an exemplary network entity 900 according to an implementation form. The network entity 900 may be located within the OAM 421 of the second network 220 OP-B as described above with respect to Figures 2 to 7. The network entity may implement the Operation and Maintenance (OAM) function 421 of OP-B 220 as described above with respect to Figs. 2 to 7. The network entity 900 may particularly be an operation and maintenance (OAM) entity 421 , of at least one second network 220, e.g. as described above with respect to Figs. 2 to 7.

The network entity 900 includes a processor 903 and a transceiver 901 . The processor 903 is configured to generate a Relay Request message, e.g. a Relay Request message 402 as described above with respect to Figs. 2 to 7. The Relay Request message 402 is configured to request for a communication device, e.g. a communication device 800 as described above with respect to Figs. 2 to 8, in particular a Relay Node (RN) or a small cell, which communication device 800 is attached to at least one first network 210 and is sharable with the at least one second network 220, e.g. as described above with respect to Figs. 2 to 7.

The transceiver 901 is configured to transmit the Relay Request message 402 to the at least one first network 210 and to receive a Relay Offer message 403 from the at least one first network 210, e.g. as described above with respect to Figs. 2 to 7. The Relay Offer message 403 includes information about at least one communication device 800 that is sharable with the at least one second network 220, in particular an RN indicator 403a, e.g. as described above with respect to Figs. 2 to 7.

The Relay Request message 402 may include at least one of the following information elements 402b: location, capabilities, operating frequencies, battery levels, power availability, lease duration, mobility pattern, e.g. as described above with respect to Figs. 2 to 7. The Relay Offer message 403 may include at least one of the following information elements 403b: RN indicator 403a, cost, power availability, mobility patterns, management information, e.g. as described above with respect to Figs. 2 to 7.

The processor 903 may be configured to generate a Relay Commit message, e.g. a Relay Commit message 404 as described above with respect to Figs. 2 to 7, based on the information 403b of the Relay Offer message 403. The Relay Commit message 404 may include information about at least one preferred communication device 800 which the at least one second Network 220 prefers to share with the at least one first network 210, e.g. as described above with respect to Figs. 2 to 7. The transceiver 901 may be configured to transmit the Relay Commit message 404 to the at least one first Network 210 to which the at least one preferred communication device 800 is attached to, e.g. as described above with respect to Figs. 2 to 7.

The Relay Commit message 404 may include information about the at least one preferred communication device 800, in particular a Relay Node (RN) identifier 403a of the at least one preferred communication device 800, e.g. as described above with respect to Figs. 2 to 7.

The Relay Commit message 404 may further include at least one of the following information elements 404b: a duration of attaching the communication device 800 to the at least one second network 220, configuration and security information for enabling the communication device 800 to attach to the at least one second network 220, e.g. as described above with respect to Figs. 2 to 7. The processor 903 may be configured to initiate transmission of a force roam message 203, 405 via at least one base station 212 associated with the at least one first network 210 to the at least one preferred communication device 800, e.g. as described above with respect to Figs. 2 to 7. The force roam message 203, 405 forces the at least one preferred communication device 800 to attach via at least one second base station 222 associated with the at least one second network 220 to the at least one second network 220.

The transceiver 901 may be configured to receive an intermediate Relay Offer message 403b from the at least one first network 210 responsive to transmitting the Relay Request message 402 if no communication device 800 is attached to the at least one first network 210, as described above with respect to Fig. 6. The intermediate Relay Offer message 403b indicates that no communication device 800 is available.

The Relay Request message 402 may further include Slice Type Support information 402c indicating a desired support of the communication device 800 for specific logical network (Slice) functions, e.g. as described above with respect to Fig. 7. Beside the messages described above, the processor 903 may receive further messages, e.g. messages within the context of relay node attach procedures and/or messages as described above within the context of Figs. 4 to 7. One or more of the communication devices 800 and one or more of the network entities 900 may form a communication system, e.g. a communication system 200 as described above with respect to Figs. 2 to 3, supporting sharing of a communication device 800 between at least one first network 210 and at least one second network 220, in particular a Relay Node (RN) or a small cell as described above with respect to Figs. 2 to 7. Such communication system 200 includes: at least one second network 220 with at least one network entity 900 as described with respect to Fig. 9; and at least one first network 210 with at least one communication device 800 as described above with respect to Fig. 8, in particular a RN or a small cell, attached to the at least one first network 210. The at least one second network 220 may be configured to interact with the at least one first network 210 in order to roam the communication device 800 from the at least one first network 210 to the at least one second network 220 as described above with respect to Figs. 2 to 7.

Fig. 10 shows a schematic diagram illustrating an exemplary method 1000 for sharing a communication device between at least one first network and at least one second network according to an implementation form.

The method 1000 can be applied for sharing a communication device, e.g. a communication device 800 as described above with respect to Figs. 2 to 9, in particular a relay node (RN) or a small cell, between at least one first network 210 and at least one second network 220, e.g. as described above with respect to Figs. 2 to 9.

The method 1000 includes: Receiving 1001 , by the communication device 800, a force roam message 203 from at least one first base station 212 associated with the at least one first network 210, the force roam message 203 forcing the communication device 800 to attach via at least one second base station 222 associated with the at least one second network 220 to the at least one second network 222, e.g. as described above with respect to Figs. 2 to 9.

The method 1000 further includes: generating 1002 an attach message 304 responsive to receiving the force roam message 203, the attach message 304 requesting the at least one second network 220 to attach the communication device 800 to the at least one second network 220, e.g. as described above with respect to Figs. 2 to 9. The method 1000 further includes: transmitting 1003 the attach message 304 to the at least one second BS 222 associated with the at least one second network 220, e.g. as described above with respect to Figs. 2 to 9.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the method 1000 described above with respect to Fig. 10. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the method 1000 described above. While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence. Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.