WO2018166579A1

WO2018166579A1 - Apparatus and method for nomadic relay node deployment

Info

Publication number: WO2018166579A1
Application number: PCT/EP2017/055869
Authority: WO
Inventors: Sandip GANGAKHEDKAR; Ömer BULAKCI; Josef Eichinger
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2017-03-13
Filing date: 2017-03-13
Publication date: 2018-09-20
Also published as: CN110326322A

Abstract

The present invention provides a control apparatus 100 for relay node configuration and positioning in a nomadic relay network. The control apparatus 100 is configured to receive an indication that a relay node 200 arrives at a predetermined area 300 and relay node information of the arriving relay node 200. When receiving the indication, it determines a configuration and/or position for the arriving relay node 200 in the predetermined area 300 according to the received relay node information and based on coverage and/or connectivity requirements. Finally, it informs the arriving relay node 200 of the determined configuration and/or position.

Description

APPARATUS AND METHOD FOR NOMADIC RELAY NODE DEPLOYMENT

TECHNICAL FIELD The present invention relates to a control apparatus, a relay node, and to methods, for relay node configuration and positioning in a nomadic relay node network. Positioning thereby means finding a position for a given relay node in the network, akin to node deployment. The control apparatus of the present invention may be located at a base station (BS) side of the network, or at a side of nomadic relay nodes in the network. That is, the control apparatus may be implemented either in a centralized or a distributed manner. A relay node of the present invention is preferably a nomadic relay node, i.e. a relay node that can change its position within the network.

BACKGROUND

Providing ubiquitous cellular network coverage is a great challenge, particularly in underground areas or deep indoor areas, like urban parking lots. This is mainly due to the cumulative penetration losses caused by walls, floors, and ceilings in such areas. Cellular macro-network deployments are rarely optimized for these kinds of deep coverage situations. However, ubiquitous coverage is especially important for new automotive Machine Type Communications (MTC) use-cases, such as for remote services like checking the status of a vehicle, locating vehicles in a public parking garage, autonomous-valet parking etc. Conventional solutions for providing coverage based on macro-cell deployments generally fall under the following two categorical approaches.

A first approach uses narrowband (NB) technologies for Internet of Things (IoT) or MTC based on Low Power Wide Area Networks (LPWAN). This includes 3GPP-based technologies like NB-IoT (or NB-CIoT), NB-LTE, LTE-MTC, EC-GSM-IoT etc., as well as non-3GPP technologies like LoRaWAN, SigFox etc. These solutions introduce several new developments over legacy cellular technologies, for instance: new narrowband air- interface designs, multiple-retransmission schemes, multi-subframe channel estimation, longer acquisition times, and other receiver processing related innovations. With these developments, the solutions achieve up to a 20dB link budget improvement over legacy cellular standards like LTE, almost close to the thermal noise floor. The used narrowband technologies target typical IoT and MTC scenarios like smart electricity meters, smart- water meters, smart irrigation sensors, etc., and have several attractive features like very low power consumption, long battery life, low cost chipsets, and support for massive number of connected devices.

However, the link budget improvement provided by said narrowband technologies is still not sufficient for ubiquitous coverage in deep indoor scenarios, such as underground multi-level garages, in which significant propagation losses are caused by multiple walls, grounds, floors, and other parked vehicles.

A second approach uses additional infrastructure such as Multi-Hop fixed relays and In- Building Distributed Antenna Systems (DAS). Adding, for example, fixed outdoor-to- indoor (O-to-I) relays, or using dedicated in-building DAS, can indeed solve the problem of providing coverage to deep indoor or underground areas. A telecom operator or facility owned may deploy such O-to-I relays in specific areas of a city, in order to provide indoor coverage extensions in specific areas. Similarly, DAS can deal with isolated spots of poor coverage inside, for example, large buildings, namely by installing networks of relatively small antennas throughout the buildings to serve as repeaters. The main drawbacks of fixed relays, however, are the added infrastructure costs, the accordingly increased network planning and deployment costs, and the poor scalability of the approach (because each target area requires site-specific planning and deployment).

SUMMARY

In view of the above-mentioned problems and disadvantages, the present invention aims to improve the conventional approaches. The present invention has specifically the object to provide an improved solution for cellular network deployment in deep coverage situations. The present invention thereby targets specifically automotive MTC applications. For instance, the key use-case of providing connectivity to vehicles parked in an underground and multi-level parking lot. The object of the present invention is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present invention are further defined in the dependent claims. The main idea of the present invention is maximizing the coverage in indoor/underground areas through a network of on-demand configured and/or positioned nomadic relay nodes. The nomadic relay nodes may be integrated into, or otherwise mounted onto, vehicles. Advantageously, coverage redundancy is thus maintained. Coverage redundancy can conceptually be understood as the reduction in coverage resulting from changing the position of a single relay node in a given topology of relay nodes. Hence, maintaining coverage redundancy implies a coverage guarantee or robustness against a time-varying topology of a nomadic network. It is worth noting in this respect, that to fulfill certain service requirements of the network, different key performance indicators (KPIs) or performance criteria can be defined.

Since in a network of nomadic relay nodes (called a nomadic relay network), there are inevitably relay nodes with varying relay capabilities, battery status, duration of deployment (for example, parking duration), the present invention especially provides an intelligent method for nomadic network configuration and/or positioning, in order to provide improved network coverage and a reduced number of 'coverage holes' in deep coverage situations.

A first aspect of the present invention provides a control apparatus for relay node configuration and positioning in a nomadic relay network, the control apparatus being configured to receive an indication that a relay node arrives at a predetermined area and relay node information of the arriving relay node, determine, when receiving the indication, a configuration and/or position for the arriving relay node in the predetermined area according to the received relay node information and based on coverage requirements and/or connectivity requirements, inform the arriving relay node of the determined configuration and/or position.

The predetermined area may also be an area that is changed or updated during operation of the control apparatus. Hence, the term "predetermined" does not only mean a predetermination before the nomadic node enters the area or network, but also a predetermination after this event.

A nomadic relay network may be any kind of network, in which at least one relay node, e.g. a base station or user equipment, is nomadic.

The control apparatus can be arranged in a base station or in a terminal, i.e. also in a distributed manner, in particular also as a software function. With the control apparatus of the first aspect, on-demand (through triggering by the indication) configuration and/or positioning of arriving nomadic relay nodes is enabled, especially based on coverage and/or connectivity requirements. These requirements may be defined according to a desired coverage or connectivity goal of the area. The control apparatus is able to provide nearly ubiquitous cellular network coverage, even in deep coverage situations .

Because the relay node configuration and/or positioning bases on a certain connectivity criterion and/or coverage criterion, an optimum position and/or configuration of a given relay node can be determined, in order to satisfy the desired goals. A coverage goal may, for instance, be defined based on service KPIs. The relay node's positions and/or configurations may after their initial determination, be updated dynamically and/or updated on-demand, depending, for instance, on local information from other relay nodes, in order to satisfy and maintain the desired coverage goal. A relay node may also be reconfigured depending, for instance, on the status/capabilities of any active and/or candidate relay node in the network.

The control apparatus may further provide updates to the network, e.g. to a base station or to one or more relay nodes in the area, about local changes of the coverage of the predetermined area, about current vehicle locations, and/or about vehicle capabilities (like battery status, relaying capability, antenna configurations, and/or carrier frequency support such as mm- Wave).

In a first implementation form of the control apparatus according to the first aspect, the control apparatus is included in, or associated with, a base station or another network node serving the predetermined area, or is distributed over a plurality of relay nodes in the predetermined area, or in a cloud, or in an operator-independent entity.

Thus, either a centralized control apparatus or a distributed control apparatus can be implemented for implementing the relay node configuration and/or positioning, and particularly for maintaining a dynamic relay connectivity in the predetermined area over time.

In a second implementation form of the control apparatus according to the first aspect as such or according to the first implementation form of the first aspect, the coverage requirements include that a coverage achieved by the arriving relay node at the determined position is maximized, and/or the connectivity requirements include that a number of connections between the arriving relay node at the determined position and other active relay nodes in the predetermined area is above a threshold value.

With these requirements, the coverage and/or connectivity of the predetermined area can be optimized. Alternative coverage requirements may include service requirements, for instance, defined by certain KPIs that must be fulfilled. An example of such a KPI is the minimum received power for UE's served by a particular relay node, which translates to a latency range for a particular packet size.

In a third implementation form of the control apparatus according to the first aspect as such or according to any previous implementation form of the first aspect, the control apparatus is further configured to maintain the network as an unbroken network, in which each active relay node is connected to a base station.

The term "connected" in this respect means a connectivity/reachability in terms of preferably a graph theory. This means that each connected active relay node is able to communicate, at least indirectly (e.g. over one or more other nodes), with a base station or other serving node.

As an example, the control apparatus may be configured to maintain a connectivity graph that models, preferably dynamically, the nomadic relay network at least in the predetermined area. In the connectivity graph, a node may represent an active relay node, candidate relay node, or user equipment, and an edge may represent a connection between two active relay nodes. The connectivity requirements then preferably include an unbroken graph, in which each active relay node is connected to a base station or to another network node serving at least a part of the predetermined area.

The use and maintenance of such a connectivity graph enables assessing in a simple but efficient manner, whether an unbroken network and/or the connectivity requirements are fulfilled and maintained over time. Additionally, cycles in the graph may be monitored, wherein cycles indicate that connectivity redundancies are provided, i.e. redundant connections of a certain node to the serving base station or other serving node, in particular an active relay node. Thereby, connectivity robustness in the predetermined area is significantly improved.

In a fourth implementation form of the control apparatus according to the first aspect as such or according to any previous implementation form of the first aspect, the configuration includes a relay mode that defines how information is relayed to other nodes.

A relay mode can be an amplify-and-forward (AF) mode or a decode-and-forward (DF) mode, and/or an outband mode or an inband mode, and/or an inactive mode, etc. An inactive mode is, for instance, a non-relay mode, like a UE mode or a RRM configuration. By configuring specifically the relay mode, the coverage and performance of the network can be further improved. In a fifth implementation form of the control apparatus according to the first aspect as such or according to any previous implementation form of the first aspect, the relay node information includes a relaying capability, maximum transmit power, battery status, and/or expected duration in the predetermined area of the arriving relay node. Taking into account this specific relay node information allows further optimizing the coverage and reliability of the network in the predetermined area. Further, the relay node information may also include a relay node ID and/or an ID of the predetermined area. In a sixth implementation form of the control apparatus according to the first aspect as such or according to any previous implementation form of the first aspect, the control apparatus is further configured to determine a new configuration and/or position for at least one other active or inactive relay node in the predetermined area based on the coverage and/or connectivity requirements based on an information about a status change of the network.

A status change of the network can be based on a reception of a notification indicating that: a node leaves the predetermined area, a relay node leaves the predetermined area, and/or a node changes its status, for example, with respect to battery status, etc. The control apparatus is accordingly able to provide on-demand reconfiguration and/or positioning of the network, which provides additional coverage robustness and reliability. Thus, the control apparatus is able to better maintain coverage and/or connectivity over time.

In a seventh implementation form of the control apparatus according to the sixth implementation form of the first aspect, the apparatus is further configured to determine a new position for at least one active relay node in the predetermined area, and inform said active relay node of the new position, and/or determine an active configuration for at least one inactive relay node or inactive configuration for at least one active relay node in the predetermined area, and inform said inactive relay node of the active configuration.

A second aspect of the present invention provides a relay node for a nomadic relay network, configured to send an indication that the relay node arrives at a predetermined area and own relay node information, obtain a configuration and position for the relay node in the predetermined area, execute the obtained configuration at the obtained position, and determine and send an updated coverage of the predetermined area, after the configuration is executed. The relay node is moved to the obtained position, where the obtained configuration is executed. The position may be obtained from a control apparatus that is either implemented in a centralized manner at the BS, a network node, cloud etc., as described above, or implemented in a distributed manner at the relay node itself. Thereby, the relay node participates in optimizing the coverage and/or connectivity in the network. The coverage update may be sent only once, but coverage updates may also be sent more often, for instance, periodically. A coverage update may only include a coverage gain compared to a current coverage, but may also include a complete new coverage.

In a first implementation form of the relay node according to the second aspect, the relay node is further configured to determine the updated coverage by collecting signal quality measurements from connected relay nodes or user equipment, and deriving the updated coverage from the collected measurements, or estimating the updated coverage based on measured distances between the relay node and surrounding objects and/or of a transmit power level of the relay node.

Thereby, the relay node is able to provide precise and practical coverage updates based on actual surroundings in the predetermined area, and obstacles, walls, and/or floors etc. in the predetermined area, respectively.

In a second implementation form of the relay node according to the second aspect as such or according to the first implementation form of the second aspect, the relay node is further configured to construct a radio environment map of the predetermined area based on the updated coverage and/or based on at least one received radio environment map of the predetermined area.

Thereby, over time, a complete radio fingerprint of the predetermined area can be produced, which allows identifying easily potential positions for arriving relay nodes or relay nodes to be rearranged. Further, a load on the active relay nodes in terms of number of served user equipments, can be monitored. Third party maps or sensor measurements may be combined with the radio environment map, if available, for an even more precise environment map.

In a third implementation form of the relay node according to the second aspect as such or according to any previous implementation form of the second aspect, the relay node is further configured to obtain the configuration and position by determining autonomously its configuration and position in the predetermined area based on at least one radio environment map of the predetermined area periodically received or requested by the relay node from other active relay nodes in the predetermined area and/or triggered by changes in the network.

In a fourth implementation form of the relay node according to the second aspect as such or according to any previous implementation form of the second aspect, the relay node is further configured to, when in an inactive state, monitor the coverage of the predetermined area and, transmit, in particular broadcast, own relay node information, when the coverage drops below a threshold value, or when it receives an indication from another relay node.

With such relay nodes in the predetermined area, the coverage and/or connectivity of the network may be maintained in a self-organized and very reactive manner.

In a fifth implementation form of the relay node according to the second aspect as such or according to any previous implementation form of the second aspect, the relay node is further configured to send a notification that it leaves the predetermined area, identify a suitable replacement relay node in the predetermined area, before leaving the predetermined area, send a configuration to the identified replacement relay node, in order to configure said replacement relay node according to the configuration, and in particular inform other relay nodes in the predetermined area about the configuration of the replacement relay node.

Thereby, the relay nodes in the predetermined area can maintain coverage and/or connectivity in a self-organized manner over time. Notably, the informing of the other relay nodes can also be performed by the replacement relay node.

In a sixth implementation form of the relay node according to the fourth implementation form of the second aspect, the relay node is further configured to, if being unable to identify a replacement relay node, accordingly inform at least one other relay node in the predetermined area, or instruct at least one other relay node to move into a new position in the predetermined area determined based on coverage and/or connectivity requirements. Thus, a failure in finding a suitable replacement relay node is moderated, and coverage and/or connectivity robustness is accordingly improved.

A third aspect of the present invention provides a method for relay node configuration and positioning in a nomadic relay network, the method comprising the steps of receiving an indication that a relay node arrives at a predetermined area and receiving relay node information of the arriving relay node, determining, when receiving the indication, a configuration and/or position for the arriving relay node in the predetermined area according to the received relay node information and based on coverage requirements and/or connectivity requirements, informing the arriving relay node of the determined configuration and position.

In a first implementation form of the method according to the third aspect, the method is carried out by a control apparatus included in, or associated with, a base station or another network node serving the predetermined area, or is carried out distributed over a plurality of relay nodes in the predetermined area, or in a cloud, or in an operator- independent entity.

In a second implementation form of the method according to the third aspect as such or according to the first implementation form of the third aspect, the coverage requirements include that a coverage achieved by the arriving relay node at the determined position is maximized, and/or the connectivity requirements include that a number of connections between the arriving relay node at the determined position and other active relay nodes in the predetermined area is above a threshold value.

In a third implementation form of the method according to the third aspect as such or according to any previous implementation form of the third aspect, the network is maintained as an unbroken network. In a fourth implementation form of the method according to the third aspect as such or according to any previous implementation form of the third aspect, the configuration includes a relay mode that defines how information is relayed to other nodes. In a fifth implementation form of the method according to the third aspect as such or according to any previous implementation form of the third aspect, the relay node information includes a relaying capability, maximum transmit power, battery status, and/or expected duration in the predetermined area of the arriving relay node.

In a sixth implementation form of the method according to the third aspect as such or according to any previous implementation form of the third aspect, the method includes determining a new configuration and/or position for at least one other active or inactive relay node in the predetermined area based on the coverage and/or connectivity requirements based on an information about a status change of the network.

In a seventh implementation form of the method according to the sixth implementation form of the third aspect, the method further comprises determining a new position for at least one active relay node in the predetermined area, and informing said active relay node of the new position, and/or determining an active configuration for at least one inactive relay node or inactive configuration for at least one active relay node in the predetermined area, and informing said inactive relay node of the active configuration.

The method of the third aspect and its implementation forms achieves the same advantages as the apparatus of the first aspect and its implementation forms.

A fourth aspect of the present invention provides a method for relay node configuration and positioning in a nomadic relay network, the method comprising the steps of sending an indication that a relay node arrives at a predetermined area and sending relay node information, obtaining a configuration and position for the relay node in the predetermined area, executing the obtained configuration at the obtained position, and determining and sending an updated coverage of the predetermined area, after the configuration is executed. In a first implementation form of the method according to the fourth aspect, the method further comprises determining the updated coverage by collecting signal quality measurements from connected relay nodes or user equipment, and deriving the updated coverage from the collected measurements, or estimating the updated coverage based on measured distances between the relay node and surrounding objects and/or of a transmit power level of the relay node.

In a second implementation form of the method according to the fourth aspect as such or according to the first implementation form of the fourth aspect, the method further comprises constructing a radio environment map of the predetermined area based on the updated coverage and/or based on at least one received radio environment map of the predetermined area. In a third implementation form of the method according to the fourth aspect as such or according to any previous implementation form of the fourth aspect, the method further comprises obtaining the configuration and position by determining autonomously its configuration and position in the predetermined area based on at least one radio environment map of the predetermined area periodically received or requested by the relay node from other active relay nodes in the predetermined area and/or triggered by changes in the network.

In a fourth implementation form of the method according to the fourth aspect as such or according to any previous implementation form of the fourth aspect, the method further comprises monitoring the coverage of the predetermined area, and transmitting, in particular broadcasting, own relay node information, when the coverage drops below a threshold value or when it receives an indication from another relay node.

In a fifth implementation form of the method according to the fourth aspect as such or according to any previous implementation form of the fourth aspect, the method further comprises sending a notification that a relay node leaves the predetermined area, identifying a suitable replacement relay node in the predetermined area, before the relay node leaves the predetermined area, sending a configuration to the identified replacement relay node, in order to configure said replacement relay node according to the configuration, and in particular informing other relay nodes in the predetermined area about the configuration of the replacement relay node.

In a sixth implementation form of the method according to the fourth implementation form of the fourth aspect, the method further comprises, if being unable to identify a replacement relay node, accordingly informing at least one other relay node in the predetermined area, or instructing at least one other relay node to move into a new position in the predetermined area determined based on coverage and/or connectivity requirements.

The method of the fourth aspect and its implementation forms achieves the same advantages as the relay node of the second aspect and its implementation forms.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities.

Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which:

Fig. 1 shows a control apparatus according to an embodiment of the present invention, which is configured to carry out a method according to an embodiment of the present invention.

Fig. 2 shows a relay node according to an embodiment of the present invention, which is configured to carry out a method according to an embodiment of the present invention. shows a scenario of a relay node according to the present invention entering a predetermined area and leaving a cellular coverage area. shows a connectivity graph modeling the nomadic relay network. shows a centralized mechanism for maintaining coverage and/or connectivity in case of a relay node entering a predetermined area. shows a centralized mechanism for maintaining coverage and/or connectivity in case of a relay node leaving a predetermined area. shows a distributed mechanism for maintaining coverage and/or connectivity in case of a relay node entering a predetermined area. shows a distributed mechanism for maintaining coverage and/or connectivity in case of a relay node leaving a predetermined area. shows a table comparing the present invention with the state of the art. shows a functional architecture of an Intelligent Coverage Extension Module. shows a positioning scenario of a relay node according to an embodiment of the present invention. shows tables of measurements obtained by a relay node at a position.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 shows a control apparatus 100 according to an embodiment of the present invention. The control apparatus 100 is configured to perform a method 110 according to another embodiment of the present invention for relay node configuration and positioning in a nomadic relay network. In particular, the control apparatus 100 is configured to receive 111 an indication that a relay node 200 arrives at a predetermined area 300 and relay node information of the arriving relay node 200. The control apparatus 100 may receive this indication and/or the information directly from the arriving relay node 200, and/or indirectly from a BS 301 or other node serving the predetermined area 300, and/or from one or more other relay nodes. Further, the control apparatus 100 is configured to determine 112, when receiving the indication about the arriving relay node 200, a configuration and/or position for the arriving relay node 200 in the predetermined area 300 according to the received relay node information and based on coverage requirements and/or connectivity requirements. Finally, the control apparatus 100 is configured to inform 113 the arriving relay node 200 of the determined configuration and/or position. The arriving relay node 200 may thereby be informed directly and/or indirectly, for instance via BS 301 and/or one or more other relay nodes. The arriving relay node 200 can then assume the determined position, for instance, a parking space, and/or can execute the configuration, preferably at the determined position.

Fig. 2 shows a relay node 200 according to another embodiment of the present invention. The relay node 200 is configured to perform a method 210 according to another embodiment of the present invention for relay node configuration and positioning in a nomadic relay network.

In particular, the relay node 200 is configured to send 211 an indication that the relay node arrives at a predetermined area 300 and send own relay node information. It may send the indication and/or information to a control apparats 100, and/or to a BS 301 or other serving node of the network, and/or may distribute it among one or more other relay nodes. Further, the relay node 200 is configured to obtain 212 a configuration and position for the relay node 200 in the predetermined area 300, and to execute 213 the obtained configuration at the obtained position. After the configuration is executed, the relay node 200 is configured to determine and send 213 an updated coverage of the predetermined area 300. The updated coverage may particularly be sent to a control apparatus 100, a BS 301 or other serving node of the area 300, or to one or more other relay nodes in the area 300. Fig. 3 shows a typical application scenario of the present invention. In particular, Fig. 3 shows as the predetermined area 300 a parking garage with two levels (labeled Level 0 and Level -1). The predetermined area 300 is served by at least one BS 301. The BS 301 may include or be associated with the control apparatus 100. Several vehicles (labelled Cars 1-3) are shown in the predetermined area 300. Each vehicle may each equipped with a relay node 200. The control apparatus 100 may also be distributed amongst the relay nodes 200 of the vehicles in the predetermined area 300.

A first relay node 200 is shown to enter the predetermined area 300 mounted on Car 1. A second and third relay node 200 is mounted on parked Cars 2 and 3, respectively. Upon entering the area 300, the relay node 200 of Car 1 sends a trigger indicating its arrival and own relay node information. Further, it may receive an indoor map of the area 300 from the serving BS 301. From this point onwards, one or more sensors of Car 1 (e.g. GPS/IMU, LiDAR, mm- Wave radar etc.) may determine the current position of the arriving relay node 200 in the predetermined area 300, for example, by using indoor navigation techniques.

The arriving relay node 200 of Car 1 then obtains a configuration and/or position in the predetermined area 200. For instance, the control apparatus 100 determines the configuration and/or position for the arriving relay node 200 according to the relay node information of said relay node 200 and based on coverage requirements and/or connectivity requirements. The control apparatus 100, and the BS 301, may then inform the arriving relay node 200, directly or indirectly, of the determined configuration and/or position. For instance, a nearest other relay node 200 in the area 300 (e.g. of Car 2) may provide the arriving relay node 200 of Car 1 with the configuration and/or position.

The position may particularly be determined from potential positions 401, for example, available and known parking spaces in the predetermined area 300, and may be based on a coverage metric and/or connectivity metric that is associated with each potential position 401. A coverage metric associated with a potential position 401 may indicate, for example, an estimated non-overlapping 3D coverage, should the relay node 200 of Car 1 finally occupy that potential position 401 as its determined position. The connectivity metric associated with a potential position 401 may indicate, for example, a number of active or candidate relay nodes 400 that could potentially communicate with the entering relay node 200, should it finally be placed in that potential position 401 as its determined position.

Alternatively, in case the control apparatus 100 is distributed amongst multiple or all relay nodes 200 in the predetermined area 300, the relay node 200 of Car 1 may be provided with the potential positions 401 and also with the coverage metric and/or connectivity metric associated with the potential positions 401. Then, said relay node 200 can determine the final position from the potential positions 401, either on its own or with support of other relay nodes 200 in the area 300.

Each relay node 200 in the predetermined area 300, i.e. each vehicle equipped with a relay capability, should in the end occupy a position in the area 300 such that a coverage requirement is fulfilled, for instance, that the coverage metric is maximized. Also a connectivity requirement is fulfilled, for instance, the connectivity metric is maintained above a minimum threshold.

Associated with each potential position 401 is preferably also a requirement on a relay capability and/or power consumption of the relay node 200. Thereby, some positions may not require any relay capability (due to the presence of other active relay nodes 200 in their proximity), while other positions do require a relay capability (for example, with different duty cycles, transmit powers etc.).

As over time relay nodes 200 move in and out of determined positions (parking spaces) and/or the predetermined area 300 as a whole, the network topology in the predetermined area 300 changes, and accordingly also a relaying and/or connectivity status of the network changes.

A preferred goal of the present invention is to ensure that the network is maintained as an unbroken network at all times. That is, that each relay node 200 in the predetermined area 300 should always be connected directly or indirectly to the BS 301 or to another serving node of the area 300. To this end, preferably a connectivity graph, which dynamically models the network, should be unbrokenly connected. The (dynamic) connectivity graph may be checked and maintained by the control apparatus 100 using either a centralized or a distributed signaling mechanism. Preferred signaling mechanisms are described further below.

An example of a connectivity graph, which dynamically models a nomadic relay network, is shown in Fig. 4, and may as such be used by the control apparatus 100, in order to ensure connectivity to the BS 301 or other serving node. Every node in the connectivity graph is a BS 301 or network node, an active relay node 200, a candidate relay node 400, or a regular user equipment (UE) 402. Additionally, candidate locations 401 (i.e. potential relay node positions) may preferably be included as well. Active relay nodes 200 can be connected to each other, and may in some cases be connected to more than one other active relay node 200. Candidate relay nodes 400 are, for example, parked vehicles that can become active relay nodes 200, for example, should a nearby active relay node 200 leave the predetermined area 300. Preferred signaling mechanisms ensure that such a configuration change occurs smoothly, wherein the change may necessitate re- deploying some of the existing nodes in the predetermined area 300 to maintain unbroken connections in the connectivity graph.

Cycles in the connectivity graph indicate connection redundancies, which increase the robustness of the connectivity to the changing topology of the nomadic network, especially when relay nodes 200 move in and out of the predetermined area 300 over time.

An example of coverage requirements and connectivity requirements, based on which the configuration and/or position of a relay node 200 may be determined, is now shown. Thereby, the following is assumed:

A_P ^r(t) denotes a 3D coverage at a time t achieved by a relay node r placed at a position p in the predetermined area 300.

T_P ^r(t) denotes a coverage set of UEs 402 served by the relay node r placed at the position p at the time t.

S_P ^r(t) denotes a set of connected relay nodes 200 connected to the relay node r placed at position p at the time t.

SINRij denotes the Signal to Interference and Noise Ratio for a transmission from node i to node j. Two relay nodes and j are connected, if SINRij > β∞ηη and SINRji > βοοηη, where β∞ηη is a minimum SINR threshold for node connectivity.

N^r _P(t) denotes a number of relay nodes 200 connected to a relay node r placed at position p at time t.

N^connmin is the minimum number of connected relay nodes 200 to a particular relay node. N^covmin is the minimum number of relay nodes 200 providing coverage to a particular UE 402.

A rule for a relay node r to choose a position p in the predetermined area 300 may be formulated as below:

N^r _P > N^connmin (Connectivity requirement)

Ap is maximized (Coverage requirement) An optional rule for a regular UE u to choose a position p in the predetermined area 300 may be formulated as below: u ET_P ^r , for N^covmin different relay nodes r = n,n.. N^covmm (Coverage redundancy)

= min(l, N^connmm) (relay deployment optimization) wherein it is assumed that u is a UE 402 placed at position p in the predetermined area 300.

Next, two preferred signaling mechanisms are described, which may alternatively be used to achieve and maintain an unbroken network by means of, for instance, a (dynamic) graph connectivity in a Multi-Hop relay node scenario.

In a centralized mechanism shown in the Figs. 5 and 6, the control apparatus 100 determines the optimum position and/or configuration of a relay node 200 arriving in the predetermined area 300 (shown in Fig. 5), in order to satisfy a coverage and/or connectivity goal, i.e. the control apparatus 100 determines the position based on the coverage and/or connectivity requirements. The control apparatus 100 also determines the configuration and/or positions of the relay nodes 200, in case a relay node 200 leaves the predetermined area 300 (shown in Fig. 6). The centralized mechanism has the benefit of having the global view of the predetermined coverage area 300, and the overall status of the network coverage and connectivity.

With reference to Fig. 5, the centralized signaling mechanism is described for the case that a new relay node 200 arrives together with Car 1 in the predetermined area 300. When the relay node 200 of Car 1 enters the area 300, it may send a trigger to the serving BS 301, in order to notify the event of it entering the area 300. The serving BS 301 may forward an update trigger to the control apparatus 100 (here named Control Unit) along with relay node context, such as, a relay ID (which can be mapped to a relay type and relay capability), a parking lot ID, and/or battery status.

Based on criteria comprising the relay node context, an existing coverage, an existing connectivity, and/or connectivity requirements obtained from, for example, an Intelligent Transportation System (ITS) App 500, the control apparatus 100 can then determine the optimum parking location for Car 1, i.e. the best position for the arriving relay node 200 in the predetermined area 300. The control apparatus 100 may also determine a configuration of the arriving relay node 200. The configuration may be sent to the arriving relay node 200, for example, via the serving BS 301. The configuration of the arriving relay node 200 can include parameters like a relay mode that defines how information is relayed to other nodes (e.g. including relaying operation such as AF or DF, outband or inband relaying), a UE mode, a radio resource management configuration (e.g. Tx power, antenna patterns, frequency bands), and/or the IDs of the neighboring relay nodes 200. Neighboring relay nodes 200 are those, to which a relay-to-relay link shall be established by the arriving relay node 200 (e.g. to Car 2 and/or Car 3).

Furthermore, a currently valid 3D map of the predetermined area 300 can be sent to the arriving relay node 200. On this basis, the position in the predetermined area 300 can be specified as coordinates on the provided 3D map, or as a relative location to any of the parked relay nodes 200. Besides, the position may also be defined by a radio parameter, for example, received signal power from an already parked relay node 200 with a given relay ID, to which a radio link connection can be reliably established. For example, the position may be assumed when the received power level reaches above a given threshold. The arriving relay node 200 executes the received configuration, for instance, by establishing a communication link to another relay node 200 (e.g. that of Car 3). Upon establishment of this communication link, the newly arrived relay node 200 of Car 1 can determine the current coverage, for example, by collecting the signal quality measurements from connected UEs 402, or by estimating the coverage using, for instance, parking sensors for measuring the distance to surrounding objects and/or a Tx power level. The coverage update may then be sent to the serving BS 301 over an existing connectivity link. Accordingly, in the centralized mechanism, a successful configuration of a new relay node 200 is conveyed as a coverage update.

With reference to Fig. 6, the centralized signaling mechanism is further described for the case that a relay node 200 leaves the predetermined area 300. When a relay node 200 (e.g. that of Car 3), leaves the area 300, the leaving relay node 200 may send a trigger to the serving BS 301 , in order to notify the event of leaving the area 300. The trigger can be generated, for example when the engine of Car 3 is started, or when a target location is entered into a navigation system of Car 3. The trigger message is then sent to the serving BS 301, preferably via the network of connected relay nodes 200 that maintain the connectivity, or directly when a communication link to the serving BS 301 can be established. The serving BS 301 may send the trigger, along preferably with the relay node context, as exemplified above to the control apparatus 100. The control apparatus 100 then determines the needed updates on, for example, the connectivity graph.

Two example options are here considered: determining a new position for one of the existing relay nodes 200 (e.g. that of Car 1), such that the connectivity graph is maintained. Alternatively (or additionally), configuring a new active relay node 200 from available, currently inactive candidate relay nodes 400, such that the connectivity graph is maintained unbrokenly.

The second option is illustrated in Fig. 6. Accordingly, the new relay node configuration is sent to the candidate relay node 400 of Car 2, which is currently in a UE mode, via the serving relay node 200 of Car 1. The candidate relay node 400 of Car 2 is then activated as a relay node 200, and a communication link between Car 1 and Car 2 is established. Upon the establishment of this communication link between Car 1 and Car 2, a leave ACK may be sent to Car 3, for example, by the control apparatus 100 through the serving BS 301 and eventually other connected relay nodes 200. When Car 2 is activated as a new relay node 200, an updated coverage is determined as detailed above, and the coverage update is sent to the control apparatus 100, preferably via the serving BS 301 and the relay nodes 200 in the connectivity graph. Based on the update of the coverage, the control apparatus 100 updates the currently valid 3D map of the area 300.

It is to be noted that a part of, or all of the control apparatus 100, or of its control functionality mentioned in the Figs. 5 and 6, can be located in the BS 301 or another serving node of the area 300, but also in a RAN aggregation point, or in the ITS App 500.

In a distributed mechanism shown in the Figs. 7 and 8, the control apparatus 100 for the relay configuration, node location and maintaining the connectivity is distributed across several relay nodes 200, resulting in a self-organizing ad-hoc network of nomadic relay nodes 200 that cooperatively ensure connectivity of each relay node 200 to a BS 301 of the network. That is, the control apparatus 100 is distributed over a plurality of relay nodes 200.

With reference to Fig. 7, the distributed signaling mechanism is described for the case that a relay node 200 (together with Car 1) enters the predetermined area 300 (here a parking lot), sends an indication to the BS 301, and receives a currently valid environment map of the area 300, preferably along with information on active relay nodes 200. The environment map preferably includes potential positions 401 (candidate parking locations) depending, for example, on the relaying capability of Car 1, its expected parking duration (if available), and its battery status. The information on active relay nodes 200 may include the network identities and transmission schedules of the active relay nodes 200 with reference to the timing of the serving BS 301.

All active relays nodes 200 may periodically broadcast their own version of the environment map, including available and suitable positions 401 depending on a status of an incoming relay node 200 (i.e. relay capability, expected parking duration, battery status). The transmission schedule and periodicity of active relay nodes 200 can be pre- configured by the network, or can be chosen by the relay nodes 200 in a decentralized manner from a finite set of possibilities. Any relay node 200 may sense and monitor the coverage of the BS 301. As soon as, for example, Car 1 senses the coverage of the BS 301 being below a certain threshold (e.g. based on RSSI or RSRP measurements), it may immediately broadcast its own status information (relay capability, expected parking duration, battery status etc.). This information is then picked up by nearest active relay node 200 (here that of Car 2), which may update its own periodic broadcast to contain this new information. The update is received by the at least one active relay node 200 (e.g. by Car 3) and other non-active relay nodes 400 and non-relay nodes in the coverage of Car 2. The other active relay nodes 200 (here that of Car 3) may broadcast their own updated environment maps to the nearest active relay nodes 200 (here that of Car 1, via. Car 2), which in turn updates its own environment map broadcast. Car 1 thus receives a wider environment map update of all the active relay nodes 200 in the area 300 via this chain of connected relay nodes 200.

The final position of Car 1 and its relay node 200 is decided by itself, preferably based on the cumulative and fused environment map information obtained as described above. Once Car 1 and its relay node are parked at the determined position, the relay node 200 sends an indication containing the position to the nearest active relay node 200, which then relays this indication via multi-hop relaying to the BS 301. With reference to Fig. 8, the distributed signaling mechanism is described for the case that a relay node 200 leaves the predetermined area 300. The following steps are identified in the distributed signaling mechanism.

The relay node 200 (here that of Car 2) leaving the predetermined area 300 sends an indication to, for instance, its neighbor active relay node 200, and then proceeds to identify a suitable replacement for itself. This may be based on on-demand or periodic measurement reports triggered by the serving relay node 200, or initiated by the served UEs 402 (such as that of Car 3). The measurement reports are not restricted to signal quality measurements (like RSSI, RSRP etc.), but may include vehicle status reports containing relay capability, battery levels, expected parking duration and so on.

Once the leaving relay node 200 decides on a suitable replacement, it configures and activates this as new relay node 200 (e.g. that of Car 3), and informs its connected active relay node(s) 200 (e.g. that of Car 1) about this action. On receiving the relay configuration and activation command from its serving relay node 200, the new relay node 200 establishes a link with the old relay node 200, as well as with at least one active relay node 200 connected to the old relay node 200. The active relay node(s) 200 connected to the leaving relay node 200, on receiving the communication from the new relay node 200, sends an acknowledgement to the leaving relay node 200. The newly configured active relay node 200 begins its periodic broadcasting of updated environment map, and UEs 402 in its coverage area eventually associate themselves to the newly active relay node 200 according to their sleep/wake cycles.

If there are no suitable relay nodes 200 that can satisfy the coverage and/or connectivity requirements, the leaving relay node 200 has two options: informing its connected active relay nodes 200 to find suitable replacements, in which case the process of finding a suitable replacement is repeated at these relay nodes 200, or instructing a candidate relay node 400 to move into a suitable position 401, so that it can fulfil the coverage and/or connectivity requirements.

The Table shown in Fig. 9 gives a qualitative comparison of the present invention with a conventional narrowband LPWAN solution, namely NB-IoT, as well as with a dedicated infrastructure-based solution, like Multi-Hop fixed relays. It can be seen that with the present invention, the existing infrastructure is advantageously utilized, which is not the case for the dedicated infrastructure-based solution. Further, the present invention is sufficient for deep indoor coverage, and fulfills automotive remote service use cases without extra cost, which is not the case for narrowband LPWAN solutions. Further, while the present invention introduces new signaling mechanisms, these are not delay- critical.

Further, specific use cases, to which the present invention can be applied, are described in the following.

One use case is an Intelligent Coverage Extension Module (ICEM) as shown in Fig. 10. It is specifically proposed to implement a control apparatus 100 according to an embodiment of the present invention as a new 5G feature in the ICEM. Thereby, 'Intelligent Coverage Extension' (ICE) may be implemented as a software module on an existing NB-IoT or LTE(-M/CatO) modems The result is a legacy NB-IoT or LTE- M/CatO modem with an Intelligent Coverage Extension Module (ICEM) providing intelligent and enhanced coverage extension according to the abilities of the control apparatus 100 according to embodiments of the present invention.

Another use case is a Dynamic Radio Environment Map (DREM) shown in Fig. 11. This proposed use case requires the nomadic nodes (relay nodes 200 or otherwise) to make radio measurements, and construct radio environment maps of the predetermined area 300, in order to participate in the scheme. These environment maps are also referred to as Dynamic Radio Environment Maps (LDREM), since they are dynamic, because they change over time and space, and are based on radio measurements.

Considering the specific scenario of Fig. 11, which shows the plan view of a predetermined area 300 (here a parking lot), the individual positions (here parking spaces) are marked as Al ... A30. Shaded vehicles are the currently active relay nodes 200 (nomadic), which provide coverage extension to the other vehicles. In Fig. 11, particularly the coverage provided by the active relay node 200 at positions A17 is shown. Each positioned relay node 200 triggers radio measurements from its served users (D2D) to construct a local dynamic radio environment map (LDREM). Local, because the measurements are local to the parked relay node 200 in question. For example, the LDREM of relay node 200 at position A17 might look as shown in the upper part of Fig. 12.

The upper part in Fig. 12 includes radio measurements, here exemplarily RSSI (dBM), of the relay node 200 at positions A17 with respect to the other nodes at positions Al ... A16, A18...A30. The upper part include empty places depending on the size and occupancy of the area 300, shadowing etc.

As all active relay nodes 200 should be connected (i.e. form an unbroken connectivity graph), no active relay node 200 is isolated or disconnected. Active relay nodes 200 may share their respective LDREMs, and may build a Global Dynamic Radio Environment Map (GDREM) of the area 300, as is shown in the lower part of Fig. 12. This crowdsourced GDREM can provide a complete RF-fmgerprint of the area 300, including potential free parking positions 401, and/or a load on the active relay nodes 200. It can also be supplemented with additional context information, such as node capability, estimated parking duration, battery status etc. The GDREM may be input to the above proposed mechanisms of centralized/distributed relay node 200 deployment and configuration. The LDREM/GDREMs may optionally integrate 3^rd party maps or sensor measurements, if available, for a more fine-grained environment map.

In summary, the present invention achieves the following differences to conventional solutions, particularly to conventional LTE relaying: LTE Relaying design is only for two-hop communication. Multi-hop is not supported therein, i.e. not more than two hops are possible. Further, there is no automated mechanism in LTE relaying to establish multi-hops. Battery consumption is not taken into account, because there is usually fixed power supply. Further, the mode of a relay node is fixed in LTE relaying, and is either AF or DF.

To the contrary, with the present invention more than two hops are supported, and the relay nodes 200 can be configured with modes based on coverage and/or connectivity requirements. The relay nodes 200 may also be configured as a UE 402. Further, the relay mode and connectivity among the relay nodes 200 can be decided based on the information elements (e.g., measurements collected), as well as battery status.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. Control apparatus for relay node configuration and positioning in a nomadic relay network, the control apparatus being configured to

receive an indication that a relay node arrives at a predetermined area and relay node information of the arriving relay node,

determine, when receiving the indication, a configuration and/or position for the arriving relay node in the predetermined area according to the received relay node information and based on coverage requirements and/or connectivity requirements,

inform the arriving relay node of the determined configuration and/or position.

2. Control apparatus according to claim 1, wherein the control apparatus

is included in, or associated with, a base station or another network node serving the predetermined area, or

is distributed over a plurality of relay nodes in the predetermined area, or in a cloud, or in an operator-independent entity.

3. Control apparatus according to claim 1 or 2, wherein

the coverage requirements include that a coverage achieved by the arriving relay node at the determined position is maximized, and/or

the connectivity requirements include that a number of connections between the arriving relay node at the determined position and other active relay nodes in the predetermined area is above a threshold value.

4. Control apparatus according to one of claims 1 to 3, further configured to

maintain the network as an unbroken network, in which each active relay node is connected to a base station.

5. Control apparatus according to one of the claims 1 to 4, wherein

the configuration includes a relay mode that defines how information is relayed to other nodes.

6. Control apparatus according to one of claims 1 to 5, wherein the relay node information includes a relaying capability, maximum transmit power, battery status, and/or expected duration in the predetermined area of the arriving relay node.

7. Control apparatus according to one of the claims 1 to 6, further configured to

determine a new configuration and/or position for at least one other active or inactive relay node in the predetermined area based on the coverage and/or connectivity requirements based on an information about a status change of the network.

8. Control apparatus according to claim 7, further configured to

determine a new position for at least one active relay node in the predetermined area, and inform said active relay node of the new position, and/or

determine an active configuration for at least one inactive relay node or inactive configuration for at least one active relay node in the predetermined area, and inform said inactive relay node of the active configuration.

9. Relay node for a nomadic relay network, configured to

send an indication that the relay node arrives at a predetermined area and own relay node information,

obtain a configuration and position for the relay node in the predetermined area, execute the obtained configuration at the obtained position, and

determine and send an updated coverage of the predetermined area, after the configuration is executed.

10. Relay node according to claim 9, further configured to determine the updated coverage by

collecting signal quality measurements from connected relay nodes or user equipment, and deriving the updated coverage from the collected measurements, and/or estimating the updated coverage based on measured distances between the relay node and surrounding objects and/or of a transmit power level of the relay node.

11. Relay node according to claim 9 or 10, further configured to construct a radio environment map of the predetermined area based on the updated coverage and/or based on at least one received radio environment map of the predetermined area.

12. Relay node according to one of claims 9 to 11, further configured to obtain the configuration and position by

determining autonomously its configuration and position in the predetermined area based on at least one radio environment map of the predetermined area periodically received or requested by the relay node from other active relay nodes in the predetermined area and/or triggered by changes in the network.

13. Relay node according to one of the claims 9 to 12, further configured to, when in an inactive state,

monitor the coverage of the predetermined area, and

transmit, in particular broadcast, own relay node information, when the coverage drops below a threshold value or when it receives an indication from another relay node.

14. Relay node according to one of claims 9 to 13, further configured to

send a notification that it leaves the predetermined area,

identify a suitable replacement relay node in the predetermined area, before leaving the predetermined area,

send a configuration to the identified replacement relay node, in order to configure said replacement relay node according to the configuration, and in particular inform other relay nodes in the predetermined area about the configuration of the replacement relay node.

15. Relay node according to claim 14, further configured to, if being unable to identify a replacement relay node,

accordingly inform at least one other relay node in the predetermined area, or instruct at least one other relay node to move into a new position in the predetermined area determined based on coverage and/or connectivity requirements.

16. Method for relay node configuration and positioning in a nomadic relay network, the method comprising the steps of receiving an indication that a relay node arrives at a predetermined area and relay node information of the arriving relay node,

determining, when receiving the indication, a configuration and/or position for the arriving relay node in the predetermined area according to the received relay node information and based on coverage and/or connectivity requirements,

informing the arriving relay node of the determined configuration and position.

17. Method for relay node configuration and positioning in a nomadic relay network, the method comprising the steps of

sending an indication that a relay node arrives at a predetermined area and relay node information,

obtaining a configuration and position for the relay node in the predetermined area,

executing the obtained configuration at the obtained position, and

determining and sending an updated coverage of the predetermined area, after the configuration is executed.