Network node and methods therein for monitoring system coverage in a wireless communication network

A first network node (111) and method therein for monitoring inactive mode coverage for a user equipment (130) in a wireless communication network (100) are disclosed. A plurality of network nodes (111, 112) operate in the wireless communication network (100) and the first network node (111) is a serving network node for the user equipment (130). The first network node (111) receives an inactive mode coverage monitoring report. The first network node (111) analyzes the inactive mode coverage monitoring report and determines whether the user equipment (130) has inactive mode coverage based on the outcome of analysing the inactive mode coverage monitoring report.

TECHNICAL FILED

Embodiments herein relate to a network node and method therein for monitoring system coverage in a wireless communication network. In particular, they relate to monitor inactive mode coverage for a user equipment in a wireless communication network.

BACKGROUND

In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or user equipments (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a WI-FI access point or a radio base station (RBS), which in some networks may also be denoted, for example, a “NodeB” or “eNodeB”. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.

A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth Generation (5G) network.

3GPP 5G New Radio (NR) is the wireless standard that will become the foundation for the next generation of mobile networks.FIG. 1depicts an overview of the downlink (DL) based active mode mobility (AMM) solution proposed for 3GPP 5G NR.

As shown inFIG. 1, a UE is served by the leftmost network node, i.e. the serving node1, but is traveling in the direction towards the rightmost network node2, depicted by the dashed arrow in the figure. The UE uses the best “home MRS” (Mobility Reference Signal) for coarse timing estimation and radio link quality monitoring and failure detection, denoted by the dot filled oval in the figure. Alternative names instead of MRS may be Active mode synch signal (AMSS), active mode reference signal or Channel State Information Reference Signal (CSI-RS).

In addition, the UE monitors a sparse periodic MRS from the serving network node1and compares it with similar periodic and sparse MRSs from potential target network nodes, e.g. the network node2. When a target network node becomes relevant for a more detailed handover procedure additional dynamically configured home MRSs from the serving network node1and dynamically configured away MRSs from the target network node, e.g. the network node2, may be activated.

The final handover decision is taken by the network and it is based on UE reports containing measurements of home MRSs and away MRSs.

An example of a proposed system information acquisition for 5G NR is depicted inFIG. 2. In the example each network node, which may also be referred as RBS, eNB, gNB, transmission and reception point (TRP), transmits a synchronization signal or a system signature signal (SS). Together with the SS each network node also transmits a physical broadcast channel (PBCH) containing some of the minimum system information that the UE need to access the network. This part of the minimum system information is denoted as master information block (MIB) in the figure. The transmission of SS and the physical broadcast channel (PBCH) containing the MIB is denoted with dot filled ovals in the figure.

By reading the MIB the UE receives information on how to receive the system information block (SIB) table. The SIB table may be transmitted using a broadcast format such as single frequency network (SFN) transmission and it is depicted with a dashed oval in the figure.

In addition to the minimum system information that is periodically broadcasted in the SS+MIB and in the SIB-table the UE may receive other system information e.g. by a dedicated transmission after initial access is established, depicted with an oval with label “Additional SI transmission” in the figure.

In 5G NR, which is designed to support high gain and dynamic beamforming, e.g. by means of utilizing hundreds of antenna elements at the base station, so called massive multiple-input-multiple-output (MIMO). It is therefore possible to maintain a connection with a UE despite that it is beyond an idle mode coverage or inactive mode coverage of the serving network node. The idle or inactive mode coverage, also referred to as SS coverage or SS broadcast area or system area coverage, is defined by the system information or system signature signal coverage, of a network node. That is with 5G NR, the possibility of beam formed data transmissions enables a UE to travel far away from its serving network node with a maintained radio quality. This means that the UE could move out of the SS broadcast area, or system area, of the serving network node, but still be connected to the serving network node. As long as the UE is still within a serving area or SS coverage of another network node in the network, this will not be a problem. As a UE that is dropped of connection due to some reason could easily reconnect to the network by retrieving the system information from that node. However, if the UE moves in to an inactive mode coverage hole, i.e. an area where none of the network nodes in the network broadcasts an SS, a UE that drops connection will not be able to reconnect to the network. This is because the UE cannot retrieve the information needed to do initial access.

FIG. 3depicts an example of the problems identified above in prior art. As shown inFIG. 3, the UE is in an area where there is no SS coverage from any base stations, e.g. SS1, SS2, SS3from the network nodes31,32,33cannot reach the UE. This mismatch in active mode coverage and inactive mode coverage will create a number of problems. The active mode coverage means that the UE has a Radio Resource Control (RRC) connection and is involved in transmission and reception of packet burst (note that it needs not transmit/receive constantly). Inactive/idle mode or state means that the UE has no RRC state in the network node, meaning that it has no radio bearers configured.

Firstly, this may cause a false sense of security to a user. A user with a UE that has an active mode connection to the network is under the impression that it can use the UE to make an emergency call, or some other important call, in the same position. For example, a user is travelling with its boat further out in the sea, i.e. is moving out of the Inactive Mode Coverage of the network. In case the UE would lose connection, the user would turn the boat around and go closer to the harbour again. However, as the UE is still connected to the network, the user is under an impression that it will be possible to call for help if it is needed. When the UE battery runs out, the UE drops and loses the connection to the network. The user has a backup battery to power on the UE, and tries to reconnect to the network. This is however not possible, as the UE cannot retrieve the information needed to do initial access.

Secondly, this may cause comparison problem. For example, two users with the same operator are standing next to each other in an area with no Inactive Mode Coverage of the network. User A has an active mode connection between the UE and the network which started before he is moving in to the area, and the active mode connection is now supported through beam forming. User B picks up the phone to make a call, but cannot connect since his UE is unable to retrieve any access information to the network. User B may get disappointed with the operator since the same service is not provided for both users, even though they are at the same location, have the same subscription and are paying an equal amount of money to the operator.

SUMMARY

Therefore it is an object of embodiments herein to provide a technique for monitoring inactive mode coverage for a user equipment in a wireless communication network.

According to a first aspect the object is achieved by a method performed in a first network node for monitoring inactive mode coverage for a user equipment (UE) in a wireless communication network. A plurality of network nodes operates in the wireless communication network and the first network node is a serving network node for the user equipment.

The first network node receives an inactive mode coverage monitoring report.

The first network node analyses the inactive mode coverage monitoring report and determine whether the user equipment has inactive mode coverage based on the outcome of analysing the inactive mode coverage monitoring report.

According to some embodiments, the inactive mode coverage monitoring report comprises synchronization signals, SSs, monitoring report or system information, SI, signal monitoring report.

According to some embodiments, the first network node may send a monitoring request to the user equipment to monitor SSs or SI of the wireless communication network.

According to some embodiments, the first network node may send a monitoring request via enhancements to the Radio Resource Control (RRC) Connection Reconfiguration.

According to some embodiments, the first network node may provide a transmission gap or several transmission gaps to the UE for measuring SSs or SI of the wireless communication network.

According to some embodiments, the user equipment may be configured to keep measuring SS from the serving network node, at least at some occasions, and/or detect and measure neighbour SSs from neighbour network nodes, at least at some occasions.

According to some embodiments, the first network node may send a request to neighbouring network nodes for SS information to be used in analysing the monitoring report. The SS information may comprise SS periodicity and/or SS transmission occasions.

According to some embodiments, the first network node may receive the SI signal monitoring report from the user equipment and the SI signal monitoring report comprises SI challenge information received by the user equipment from a target network node.

According to some embodiments, the first network node may send a SI challenge request to a target network node and receive a SI challenge response containing a SI challenge information from the target network node to be used in analysing the monitoring report.

According to some embodiments, when it is determined from the inactive mode coverage monitoring report analysis that the UE does not have Inactive Mode Coverage, the first network node may send an indication to the user equipment for informing the user equipment of no inactive mode coverage. Alternatively, the first network node may release the connection to the user equipment or may indicate to the user equipment that the connection will be released after a timer has expired. In this case, the first network node may receive from the user equipment a request to prolong the timer.

According to some embodiments, the first network node may provide a dedicated SS coverage to the user equipment.

According to some embodiments, the first network node may send a SS retention configuration to the user equipment.

According to some embodiments, the retention configuration may comprise any one of:

a) a SS Retention Timer value;

b) a SS Retention search space or time-frequency resources where the dedicated SS is transmitted;

c) a random access and/or random access response configuration for Random Access (RA) in retention mode;

d) a SS Retention data configuration information comprising Cell-Specific Reference Signal (CRS), scrambling, identifiers, retransmission schemes.

According to some embodiments, the SS Retention Configuration may be transmitted via dedicated transmissions during active mode, or via broadcast information.

According to some embodiments, the first network node may request neighbouring network nodes to transmit beam formed SS in a direction of the user equipment.

According to a second aspect the object is achieved by a first network node for monitoring inactive mode coverage for a user equipment (UE) in a wireless communication network. A plurality of network nodes operate in the wireless communication network and the first network node is a serving network node for the user equipment.

The first network node is configured to receive an inactive mode coverage monitoring report.

The first network node is further configured to analyse the inactive mode coverage monitoring report and determine whether the user equipment has inactive mode coverage based on the outcome of analysing the inactive mode coverage monitoring report.

According to some embodiments, the inactive mode coverage monitoring report may comprise synchronization signals, SSs, monitoring report or system information, SI, signal monitoring report.

According to some embodiments, the first network node may be further configured to send a monitoring request to the user equipment to monitor SSs or SI of the wireless communication network.

According to some embodiments, the first network node may further be configured to send a monitoring request via enhancements to the Radio Resource Control (RRC) Connection Reconfiguration.

According to some embodiments, the first network node may be further configured to provide a transmission gap or several transmission gaps to the UE for measuring SSs or SI of the wireless communication network.

According to some embodiments, the user equipment may be configured to keep measuring SS from the serving network node, at least at some occasions, and/or detect and measure neighbour SSs from neighbour network nodes, at least at some occasions.

According to some embodiments, the first network node may be further configured to send a request to neighbouring network nodes for SS information to be used in analysing the monitoring report. The SS information may comprise SS periodicity and/or SS transmission occasions.

According to some embodiments, the first network node may be further configured to receive the SI signal monitoring report from the user equipment and the SI signal monitoring report comprises SI challenge information received by the user equipment from a target network node.

According to some embodiments, the first network node may be further configured to send a SI challenge request to a target network node and receive a SI challenge response containing a SI challenge information from the target network node to be used in analysing the monitoring report.

According to some embodiments, when it is determined from the inactive mode coverage monitoring report analysis that the UE does not have Inactive Mode Coverage, the first network node may be further configured to send an indication to the user equipment for informing the user equipment of no inactive mode coverage. Alternatively, the first network node may be further configured to release the connection to the user equipment or to indicate to the user equipment that the connection will be released after a timer has expired. In this case, the first network node may receive from the user equipment a request to prolong the timer.

According to some embodiments, the first network node may be further configured to provide a dedicated SS coverage to the user equipment.

According to some embodiments, the first network node may be further configured to send a SS retention configuration to the user equipment.

According to some embodiments, the retention configuration may comprise any one of:

a) a SS Retention Timer value;

b) a SS Retention search space or time-frequency resources where the dedicated SS is transmitted;

c) a random access and/or random access response configuration for Random Access (RA) in retention mode;

d) a SS Retention data configuration information comprising Cell-Specific Reference Signal (CRS), scrambling, identifiers, retransmission schemes.

According to some embodiments, the SS Retention Configuration may be transmitted via dedicated transmissions during active mode, or via broadcast information.

According to some embodiments, the first network node may be further configured to request neighbouring network nodes to transmit beam formed SS in a direction of the user equipment.

According to the embodiments herein, an inactive mode coverage monitoring report for a UE is received and analyzed. The UE may be requested to monitor its inactive mode coverage, i.e. the SS or SI at regular occasions. If it is detected that the UE do not have Inactive Mode Coverage, the network can either drop the connection, or make preparations to be able to help the UE to reconnect if it drops connection. For example, the network node may through temporary, beam formed system information transmissions, i.e. provide a dedicated SS coverage to the user equipment, to help the UE establish a connection again. The network node may also indicate to the UE that it does not have Inactive Mode Coverage.

With the proposed solutions, situations where a false sense of security is given to the user, as well as situations with unhappy customers experiencing the comparison problem, may be avoided. In the case where a UE with an especially important ongoing call, such as an emergency call, moves out of the Inactive Mode Coverage area, the network could make preparations to help the UE to reconnect if it drops connection, for example through temporary, beam formed system information transmissions, i.e. a SS retention procedure to re-establish a connection.

Therefore by letting the UE monitor and report on the SS or SI, it may be detected when a UE moves out of the SS or SI coverage. The serving base station may notify the UE and/or release the connection. The serving base station may also beam form the SS towards the UE in case it drops connection, in order to enable the possibility to reconnect to the network.

DETAILED DESCRIPTION

Embodiments herein relate to a communication networks in general.FIG. 4is a schematic overview depicting a communication network100. The communication network100may be a wireless communications network comprising one or more RANs and one or more CNs. The communication network100may use a number of different technologies, such as WI-FI, Long Term Evolution (LTE), LTE-Advanced, 5G, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WIMAX), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. Embodiments herein relate to recent technology trends that are of particular interest in a 5G context, however, embodiments are also applicable in further development of the existing wireless communication systems such as e.g. WCDMA and LTE.

In the wireless communication network100, wireless devices e.g. a user equipment130such as a mobile station, a non-access point (non-AP) STA, a STA, a user equipment and/or a wireless terminals, communicate via one or more Access Networks (AN), e.g. RAN, to one or more core networks (CN). It should be understood by the skilled in the art that “wireless device” is a non-limiting term which means any terminal, wireless communication terminal, user equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell. The terms user equipment130, UE, UE130and wireless device130are used interchangeable herein.

Network nodes operate in the wireless communication network100such as a first network node111and a second network node112. The first network node111provides radio coverage over a geographical area, a service area11, which may also be referred to as a SS broadcast area, or system area, or a beam or a beam group where the group of beams is covering the service area of a Radio Access Technology (RAT), such as 5G, LTE, WI-FI or similar. The second network node112provides radio coverage over a geographical area, a service area12, which may also be referred to as a SS broadcast area, or system area, or a beam or a beam group where the group of beams is covering the service area of a RAT, such as 5G, LTE, WI-FI or similar. As shown inFIG. 4, the UE130is served by a data beam114, i.e. an active mode beam, from the first network node111, but with System Information coverage, i.e. the service area12, from the second network node112.

The first and second network nodes111and112may be a transmission and reception point e.g. a radio access network node such as a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, a gNB, an evolved Node B (eNB, eNode B), a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a wireless device within the service area served by the respective first and second network nodes111and112depending e.g. on the first radio access technology and terminology used. The first and second network nodes111and112may be referred to as a serving radio network node and communicates with the wireless device120with Downlink (DL) transmissions to the user equipment130and Uplink (UL) transmissions from the wireless device130.

A signal flow chart of an example method performed in a wireless communication network100for monitoring system coverage or inactive mode coverage for a UE according to embodiments herein is illustrated inFIG. 5.

As described in the background, the idle or inactive mode coverage, also referred to as SS coverage or SS broadcast area or system area coverage, system coverage, is defined by the system information or system signature signal coverage of a network node. So please note that the terms “idle or inactive mode coverage”, “SS coverage or SS broadcast area”, “system area coverage”, “system coverage” are used interchangeably in this document.

The steps of the embodiment are described below.

In a first, optional step510, the Serving base station RBS, i.e. the network node111, sends a request to the UE130to monitor SSs of the wireless communication network100.

According to some embodiments, this is done via enhancements to the Radio Resource Control (RRC) Connection Reconfiguration.

If the request does not come until a time window has expired the UE130may discard the information about the accessed SS.

Optionally, the serving Base Station RBS111may provide a transmission gap or several transmission gaps to the UE130, in which the UE130may measure, in step520, for SS transmissions.

The UE130may be configured to keep measuring its SS from the serving RBS111, at least at some occasions, and/or detect and measure neighbor SSs from the neighbor network nodes, at least at some occasions.

The UE130sends a report, e.g. an SS Monitoring report, in step530, containing information related to the measurement, to indicate that it has a SS Coverage, independent of whether the SS is transmitted from serving Base Station111or by some other Base Stations, e.g. the network node112, in the wireless communication network100.

In case no SS is detected, the UE130may send a report to the serving Base Station111to indicate lack of SS coverage.

In an alternative mode, the UE may refrain from sending a report in case no SS coverage has been detected.

The serving base station111makes, in step540, an SS Monitoring Report Analysis, in which it determines whether the UE has SS coverage or not.

In case the SS Monitoring Report Analysis shows that the UE does not have Inactive Mode Coverage, the serving Base Station111may perform differently according to the following alternatives.

According to one embodiment, the serving Base Station111may, in step550, send a “No SS coverage indication” to the UE. This may be used to indicate to the user that it will not be able to reconnect to the network upon a connection drop.

According to one embodiment, the serving Base Station111may optionally release the connection to the UE, in step560.

According to one embodiment, the serving Base Station111may optionally indicate to the UE that the connection will be released after a timer has expired. Optionally, the UE may respond to the serving Base Station111to request a prolonged timer.

According to some embodiments, the serving base station RBS111may request neighboring base stations for information which can be used in the SS Monitoring Report Analysis to verify that the UE130do have SS coverage from the wireless communication network100. Such information may include SS periodicity and/or SS transmission occasions, etc.

In order to minimize the signaling needed for determining if the UE130has inactive mode coverage, there are two different ways:

According to one embodiment, the UE130may not send the SS Monitoring report in case no SS was found, i.e. no SS Monitoring report is received in the serving base station111. The absence of an SS Monitoring Report from the UE130may be then interpreted as a negative-acknowledgement (NACK), i.e. that the UE do not have SS Coverage, by the serving base station111.

According to one embodiment, the UE130may not send the SS Monitoring report in case one or more SS is found. The absence of an SS Monitoring Report from the UE130may then be interpreted as an indication of SS Coverage by the serving base station130.

According to some embodiments, the serving Base Station RBS111may, for example if the call is identified as prioritized, for example an emergency call or a call of a “Gold user”, try to provide a dedicated SS coverage after the release of the connection, which may be referred to as SS Retention. In this case the serving Base Station RBS111may still keep the connection to the UE even upon receiving a NACK in the SS Monitoring Report. In case the UE eventually drops connection, the serving base station RBS111may transmit beam formed SS in the latest known direction of the UE130, and possibly in nearby directions, during a limited time, in order to enable the possibility to reconnect to the wireless communication network100for the UE130.

A signal flow chart describing an example of a SS retention procedure is illustrated byFIG. 6, which comprises the following actions or steps:

The serving network node RBS111may, in step610, send a SS Retention Configuration to the UE130.

According to some embodiments, the UE130may be configured with the SS Retention Configuration which may comprises:a SS Retention Timer value. The SS Retention Timer value is to inform about for how long the network will try to maintain SS coverage for the UE130after a drop or loss of connection. This is shown inFIG. 6, in step620, where when the SS Retention Timer started, the network will try to maintain SS coverage until an Active mode connection is established, then the SS retention procedure is terminated;a SS Retention search space or time-frequency resources where the dedicated SS will be transmitted;a random access and/or random access response configuration for Random Access (RA) in retention mode;a SS Retention data configuration information comprising Cell-Specific Reference Signal (CRS), scrambling, identifiers, retransmission schemes, etc.

According to some embodiments, the SS Retention Configuration may be configured and transmitted via dedicated transmissions during active mode, or via broadcast information.

The serving base station RBS111may also request neighboring Base Stations to transmit beam formed SS in the direction of the UE, for example based on beam relations between the Base Stations.

FIG. 7depicts an alternative embodiment for monitoring inactive mode coverage for a UE, involving transmitting a message in the broadcasted system information (SI) from a potential target network node. In this example embodiment, a specific information element is broadcasted, herein referred to as SI challenge information, for enabling the serving network node RBS111to verify that the UE130actually succeeded in reading the system information transmitted from another target RBS. The serving network node RBS111can use the SI challenge information to verify that the UE130actually succeeded in reading the system information transmitted from another target RBS. So the SI challenge information is information that the UE130would not be able to retrieve if it could not read the SI. As shown inFIG. 7, the embodiment comprises the following actions or steps:

The potential target network node, e.g. the network node RBS112, generates, in step710, SI challenge information and broadcasts it via system information (SI) broadcast;

The UE130receives SI containing the SI challenge information from the network node RBS112and read the SI challenge information, in step720;

The UE130sends a SI monitoring report containing the SI challenge information, in step730;

The serving network node RBS111sends a SI challenge request to the network node112, in step740; The network node RBS112sends a SI challenge response containing SI challenge information to the serving network node RBS111, in step750;

The serving network node RBS111checks the SI challenge information received from the UE130and the network node RBS112, in step760, to determine if the UE130actually succeeded in reading the system information transmitted from the network node112;

If it is determined that the UE130is not able to read the SI, the network node RBS112may send a No SI coverage indication to the UE130, in step770; and/or the network node112may release the connection to the UE130, in step780.

Example Embodiments will be described in the following.

FIG. 8illustrates actions of a method according to embodiments herein from a first network node111perspective in a wireless communication network100. A plurality of network nodes operates in the wireless communication network100and the first network node111is a serving network node for the user equipment. The actions depicted in the dashed line box are optional and the actions may be performed in different order.

The first network node111may send a monitoring request to the user equipment130to monitor SSs or SI of the wireless communication network.

According to some embodiments, the first network node111may send a monitoring request via enhancements to the Radio Resource Control (RRC) Connection Reconfiguration.

The first network node111may provide a transmission gap or several transmission gaps to the UE130for measuring SSs or SI of the wireless communication network100.

According to some embodiments, the user equipment130may be configured to keep measuring SS from the serving network node111, at least at some occasions, and/or detect and measure neighbour SSs from neighbour network nodes, at least at some occasions.

The first network node111receives an inactive mode coverage monitoring report.

According to some embodiments, the inactive mode coverage monitoring report comprises synchronization signals, SSs, monitoring report or system information, SI, signal monitoring report.

The first network node111may send a request to neighboring network nodes for SS or SI information.

According to some embodiments, the first network node111may send a request to neighbouring network nodes for SS information to be used in analysing the monitoring report. The SS information may comprise SS periodicity and/or SS transmission occasions.

According to some embodiments, the first network node111may receive the SI signal monitoring report from the user equipment130and the SI signal monitoring report comprises SI challenge information received by the user equipment130from a target network node.

According to some embodiments, the first network node111may send a SI challenge request to a target network node and receive a SI challenge response containing a SI challenge information from the target network node to be used in analysing the monitoring report.

The first network node111analyses the inactive mode coverage monitoring report to determine whether the user equipment130has inactive mode coverage based on the outcome of analysing the inactive mode coverage monitoring report.

The first network node111determines whether the user equipment130has inactive mode coverage based on the analyses of the inactive mode coverage monitoring report.

According to some embodiments, when it is determined from the monitoring report analysis that the UE130does not have Inactive Mode Coverage, the first network node111may perform the following actions:

The first network node111send an indication to the user equipment130for informing the user equipment130of no inactive mode coverage.

The first network node111may release the connection to the user equipment130.

The first network node111may indicate to the user equipment130that the connection will be released after a timer has expired. In this case, the first network node111may receive from the user equipment130a request to prolong the timer.

To help the UE130to reconnect to the network when it enters into an inactive mode coverage hole, the following actions may be performed:

The first network node111may provide a dedicated SS coverage to the user equipment130.

The first network node111may send a SS retention configuration to the user equipment130.

According to some embodiments, the retention configuration may comprise any one of:

a) a SS Retention Timer value;

b) a SS Retention search space or time-frequency resources where the dedicated SS is transmitted;

c) a random access and/or random access response configuration for Random Access (RA) in retention mode;

d) a SS Retention data configuration information comprising Cell-Specific Reference Signal (CRS), scrambling, identifiers, retransmission schemes.

According to some embodiments, the SS Retention Configuration may be transmitted via dedicated transmissions during active mode, or via broadcast information.

According to some embodiments, the first network node111may request neighbouring network nodes to transmit beam formed SS in a direction of the user equipment130.

In order to decrease the signaling needed for determining if the UE130has inactive mode coverage, there are some different ways depending on how the first network node111is configured.

According to one embodiment, the UE130may not send the SS Monitoring report in case no SS was found, i.e. no SS Monitoring report is received in the serving base station RBS111. The absence of an SS Monitoring Report from the UE130may be then interpreted as a negative-acknowledgement (NACK), i.e. that the UE130do not have SS Coverage, by the serving base station RBS111.

According to one embodiment, the UE130may not send the SS Monitoring report in case one or more SS is found. The absence of an SS Monitoring Report from the UE130may then be interpreted as an indication of SS Coverage by the serving base station111.

In this case, in Action820where the first network node111receives an inactive mode coverage monitoring report may be interpreted such that if there is no inactive mode coverage monitoring report received by the serving network node111, the serving network node111may be configured to determine that the UE130has no inactive mode coverage.

Alternatively, if there is no inactive mode coverage monitoring report received by the serving network node111, the serving network node111may be configured to determine that the UE130has inactive mode coverage.

To perform the method actions in the first network node111, an example embodiment of the network node111is depicted inFIG. 9.FIG. 9is a schematic block diagram illustrating a first network node111for monitoring inactive mode coverage for a user equipment130in a wireless communication network100, wherein a plurality of network nodes111112operate in the wireless communication network100. The first network node111is a serving network node for the user equipment130.

The first network node111comprises a receiving module910, a transmitting module920, a determining module930, a processing module940, a memory950etc.

The first network node111is configured to, by means of e.g. the receiving module910being configured to, receive an inactive mode coverage monitoring report.

The first network node111is further configured to, by means of e.g. the determining module930being configured to, analyse the inactive mode coverage monitoring report and determine whether the user equipment130has inactive mode coverage based on the outcome of analysing the inactive mode coverage monitoring report.

According to some embodiments, the inactive mode coverage monitoring report may comprise synchronization signals, SSs, monitoring report or system information, SI, signal monitoring report.

According to some embodiments, the first network node111may be further configured to, by means of e.g. the transmitting module920being configured to, send a monitoring request to the user equipment to monitor SSs or SI of the wireless communication network.

According to some embodiments, the first network node111may further be configured to, by means of e.g. the transmitting module920being configured to, send a monitoring request via enhancements to the Radio Resource Control (RRC) Connection Reconfiguration.

According to some embodiments, the first network node111may be further configured to, by means of e.g. the transmitting module920being configured to, provide a transmission gap or several transmission gaps to the UE130for measuring SSs or SI of the wireless communication network100.

According to some embodiments, the user equipment130may be configured to keep measuring SS from the serving network node111, at least at some occasions, and/or detect and measure neighbour SSs from neighbour network nodes, at least at some occasions.

According to some embodiments, the first network node111may be further configured to, by means of e.g. the transmitting module920being configured to, send a request to neighbouring network nodes for SS information to be used in analysing the monitoring report. The SS information may comprise SS periodicity and/or SS transmission occasions.

According to some embodiments, the first network node111may be further configured to, by means of e.g. the receiving module910being configured to, receive the SI signal monitoring report from the user equipment130and the SI signal monitoring report comprises SI challenge information received by the user equipment130from a target network node.

According to some embodiments, the first network node111may be further configured to, by means of e.g. the transmitting module920being configured to, send a SI challenge request to a target network node and receive a SI challenge response containing a SI challenge information from the target network node to be used in analysing the monitoring report.

According to some embodiments, when it is determined from the inactive mode coverage monitoring report analysis that the UE130does not have Inactive Mode Coverage, the first network node111may be further configured to send an indication to the user equipment130for informing the user equipment130of no inactive mode coverage. Alternatively, the first network node111may be further configured to release the connection to the user equipment130or to indicate to the user equipment130that the connection will be released after a timer has expired. In this case, the first network node111may receive from the user equipment130a request to prolong the timer.

According to some embodiments, the first network node111may be further configured to provide a dedicated SS coverage to the user equipment130.

According to some embodiments, the first network node111may be further configured to send a SS retention configuration to the user equipment130.

According to some embodiments, the retention configuration may comprise any one of:

a) a SS Retention Timer value;

b) a SS Retention search space or time-frequency resources where the dedicated SS is transmitted;

c) a random access and/or random access response configuration for Random Access (RA) in retention mode;

d) a SS Retention data configuration information comprising Cell-Specific Reference Signal (CRS), scrambling, identifiers, retransmission schemes.

According to some embodiments, the SS Retention Configuration may be transmitted via dedicated transmissions during active mode, or via broadcast information.

According to some embodiments, the first network node111may be further configured to request neighbouring network nodes to transmit beam formed SS in a direction of the user equipment130.

According to some embodiments, the serving network node111may be configured to determine that the UE130has inactive mode coverage if there is no inactive mode coverage monitoring report received.

According to some embodiments, the serving network node111may be configured to determine that the UE130has no inactive mode coverage if there is no inactive mode coverage monitoring report received.

Those skilled in the art will appreciate that the receiving module910, the determining module930and the transmitting module920described above in the network node111may be referred to one circuit/unit, a combination of analog and digital circuits, one or more processors configured with software and/or firmware and/or any other digital hardware performing the function of each circuit/unit. One or more of these processors, the combination of analog and digital circuits as well as the other digital hardware, may be included in a single application-specific integrated circuitry (ASIC), or several processors and various analog/digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

The embodiments herein for monitoring inactive mode coverage for a user equipment130in the wireless communication network100, may be implemented through one or more processors, such as the processor960in the network node111together with computer program code970for performing the functions and actions of the embodiments herein. The program code970mentioned above may also be provided as a computer program product, for instance in the form of a data carrier980carrying computer program code for performing the embodiments herein when being loaded into the network node111. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code970may furthermore be provided as pure program code on a server and downloaded to the network node111.

The memory950in the network node111may comprise one or more memory units and may be arranged to be used to store received information, measurements, data, configurations and applications to perform the methods herein when being executed in the network node111.

As used herein, the expression “configured to” may mean that a processing circuit is configured to, or adapted to, by means of software configuration and/or hardware configuration, perform one or more of the actions described herein.

As used herein, the term “memory” may refer to a hard disk, a magnetic storage medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like. Furthermore, the term “memory” may refer to an internal register memory of a processor or the like.

As used herein, the term “computer readable medium” may be a Universal Serial Bus (USB) memory, a DVD-disc, a Blu-ray disc, a software module that is received as a stream of data, a Flash memory, a hard drive, a memory card, such as a Memory Stick, a Multimedia Card (MMC), all may be referred to data carrier980as shown inFIG. 9etc.

As used herein, the term “computer program code” may be text of a computer program, parts of or an entire binary file representing a computer program in a compiled format or anything there between.

As used herein, the terms “number”, “value” may be any kind of digit, such as binary, real, imaginary or rational number or the like. Moreover, “number”, “value” may be one or more characters, such as a letter or a string of letters. “number”, “value” may also be represented by a bit string.

As used herein, the expression “in some embodiments” has been used to indicate that the features of the embodiment described may be combined with any other embodiment disclosed herein.