WO2021230784A1

WO2021230784A1 - Methods, wireless devices and ran nodes for handling coverage holes in cells

Info

Publication number: WO2021230784A1
Application number: PCT/SE2020/050498
Authority: WO
Inventors: Mårten ERICSON; Min Wang; Tommy Arngren; Jan Christoffersson
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2020-05-14
Filing date: 2020-05-14
Publication date: 2021-11-18

Abstract

Disclosed is a method performed by a wireless device (140) connected to a radio access network, RAN, node (130) handling a cell (150). The method comprises receiving, from the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), and determining that the wireless device (140) enters one of the number of coverage holes (160), based on a position of the wireless device (140); information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes (160). Further, in response to the determining, the method comprises starting a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

Description

METHODS, WIRELESS DEVICES AND RAN NODES FOR HANDLING COVERAGE HOLES IN CELLS

Technical Field

[0001 ] The present disclosure relates generally to methods, wireless devices and radio access network (RAN) nodes for handling a wireless device when entering a coverage hole in a cell handled by the RAN node. The present disclosure further relates to computer programs and carriers corresponding to the above methods, devices and nodes.

Background

[0002] In wireless communication, wireless devices communicate wirelessly via RAN nodes of wireless communication networks. There are different radio access technologies (RAT) that wireless communication networks may use. The RATs have evolved from Global System for Mobile communication (GSM) via e.g. Wideband Code Division Multiple Access (W-CDMA) aka 3^rd Generation (3G) technology, and Long Term Evolution (LTE) aka 4^th Generation (4G) towards the latest technology called New Radio (NR) aka 5^th Generation (5G).

[0003] In NR, when a wireless device, aka user equipment (UE), loses wireless communication network coverage, i.e. loses connection with its serving RAN node, called gNodeB (gNB) in NR, the UE will trigger a measurement reporting event and send a measurement report (MR) to the gNB. The UE may determine that it is about to lose connection with the gNB by evaluating signal quality of signals sent from the gNB and when the signal quality drops below a threshold, the UE triggers sending of the MR to the gNB. The gNB will evaluate the received MR and then typically send a handover (HO) command to move the UE to another cell than the cell the UE is camping on. In some cases such a HO will not work, for example if there is a coverage hole within the cell, since in such a coverage hole no neighbor cell is typically good enough. In this case the UE will eventually trigger a Radio Link Failure (RLF), i.e. the UE will release the connection with the gNB for the cell it is camping on. Thereafter, the UE will do a cell-reselection, i.e. try to connect again with any cell. If the RLF is caused by a coverage hole, a cell-reselection will typically result in that the UE re-connects to the same cell that it was camping on, if possible. The RLF procedure is time and resource consuming as lower layer UE buffers are emptied and a possible new or different configuration has to be applied.

[0004] As captured in 3GPP TS 38.331 , V16.0.0 (2020-03), pages 537-542, the IE ReportConfigNR specifies criteria for triggering of a MR event in NR, i.e. 5G.

MR events are based on cell measurement results, which can either be derived based on Synchronization Signal/ Physical Broadcast Channel (SS/PBCH) block or Channel State Information Reference Signal (CSI-RS). These events are labelled Event AN with N equal to 1 , 2, 3 and so on, wherein Event A1 stands for “Serving cell becomes better than absolute threshold” and Event A2 stands for “Serving cell becomes worse than absolute threshold”. Event A2 would typically occur when the UE enters a coverage hole.

[0005] With the advent of wireless communication networks according to the 5^th Generation (5G) and thereafter the 6^th Generation (6G), the use of higher frequencies will increase. The very high frequencies will have substantially worse propagation situation compared to lower frequencies used in e.g. Long Term Evolution (LTE), i.e. the 4^th Generation (4G). Using these high frequencies for coverage will be very difficult without using a low frequency layer as “backup”. One property of the high frequencies is that small objects such as cars and trees may block the signal completely.

[0006] The current Radio Resource Management/ Radio Link Monitoring (RRM/RLM) functions would need to be enhanced for deployment scenarios with these high frequencies. An example is the Radio Link Failure (RLF) procedure described in 3GPP TS 38.331 referenced above. An RLF procedure is illustrated in fig. 1. As radio coverage becomes worse, the UE detects it has bad signal quality in the serving cell, e.g. that it is out of synchronization 22. After a certain amount of out of synch indications measured through counter N310 the UE is considered out of synchronization, and the UE starts 24 a timer T310. When the timer T310 has run out and the UE is still out of synchronization, the UE declares 26 a RLF, starts a second timer T311 and starts a Radio Resource Control (RRC) reestablishment. After the T311 timer has run out, the UE selects 28 a target cell, based on e.g. signal strength of signals from candidate cells. The UE then establishes 30 a connection with the selected target cell by obtaining System Information (SI) broadcasted in the target cell and sending a Random Access request to the RAN node handling the selected target cell. Thereafter, the UE obtains a grant from the RAN node handling the selected target cell and sends a RRC reestablishment request to the RAN node handling the target cell.

[0007] When an RLF event is triggered due to the UE entering a coverage hole within its serving cell, the described RLF recovery procedure may be unnecessary time consuming. One main reason for this is that the UE is put into IDLE state when RLF is triggered and need to perform the RRC reestablishment procedure. Another reason is that the RLF recovery procedure comprises multiple timers. Yet another reason is that the time the UE spends in a coverage hole may be shorter than the time for performing the RLF recovery procedure. This may result in that the UE is still within the RLF recovery procedure even though the UE has passed through the coverage hole and experiences good signal quality from the serving cell again. In addition to be an unnecessary time-consuming process for handling UEs in coverage holes, the RLF procedure may also be unnecessary resource consuming. For example, the RLF procedure causes quite substantial Random Access Channel (RACH) and RRC signaling, since the UE is put in IDLE mode, even though the UE remains in the same cell after recovery, when it has passed through the coverage hole. Yet another RLF problem is that since the UE is put in IDLE mode, the UE configurations are removed, radio bearers are teared down and the lower layers, such as Medium Access Control (MAC) layers are flushed, which means that some sessions need to be re-started completely, e.g. speech sessions.

[0008] As shown, there is a need for an improved process for handling a wireless device when entering a coverage hole in a cell. Summary

[0009] It is an object of the invention to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by using methods, RAN nodes and wireless devices as defined in the attached independent claims.

[00010] According to one aspect, a method is provided performed by a wireless device connected to a RAN node handling a cell. The method comprises receiving, from the RAN node, information on geographical positions of a number of coverage holes in the cell, and determining that the wireless device enters one of the number of coverage holes, based on a position of the wireless device, on information on quality of a signal from the RAN node being below a threshold and on the information on the geographical positions of the number of coverage holes. Further, the method comprises, in response to the determining, starting a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

[00011] According to another aspect, a method is provided performed by a RAN node of a wireless communication network, the RAN node handling a cell. The method comprises sending, to a wireless device connected to the RAN node, information on geographical positions of a number of coverage holes in the cell, and sending, to the wireless device, an instruction to stay in connected mode according to a time of a second timer for RLF triggering, when entering one of the number of coverage holes, the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes, thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

[00012] According to another aspect, a wireless device operable to be connected to a RAN node handling a cell is provided. The wireless device comprises a processing circuitry and a memory. Said memory contains instructions executable by said processing circuitry, whereby the wireless device is operative for: receiving, from the RAN node, information on geographical positions of a number of coverage holes in the cell, determining that the wireless device enters one of the number of coverage holes, based on: a position of the wireless device; information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes; and in response to the determining, starting a second timer for RLF triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

[00013] According to yet another aspect, a RAN node operable in a wireless communication network for handling a cell is provided. The RAN node comprises a processing circuitry and a memory. Said memory contains instructions executable by said processing circuitry, whereby the RAN node is operative for sending, to a wireless device connected to the RAN node, information on geographical positions of a number of coverage holes in the cell, and sending, to the wireless device, an instruction to stay in connected mode according to a time of a second timer for RLF triggering, when entering one of the number of coverage holes, the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes, thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

[00014] According to other aspects, computer programs and carriers are also provided, the details of which will be described in the claims and the detailed description.

[00015] Further possible features and benefits of this solution will become apparent from the detailed description below. Brief Description of Drawings

[00016] The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which:

[00017] Fig. 1 is a flow chart illustrating a prior art RLF procedure.

[00018] Fig. 2 is a schematic block diagram of a wireless communication network in which the present invention may be used.

[00019] Fig. 3 is a flow chart illustrating a method for handling coverage hole interruption performed by a wireless device, according to possible embodiments.

[00020] Fig. 4 is a flow chart illustrating an embodiment for facilitating determining coverage holes performed by a wireless device.

[00021] Fig. 5 is a flow chart illustrating a method for handling coverage hole interruption performed by a RAN node, according to possible embodiments.

[00022] Fig. 6 is a flow chart illustrating an embodiment for determining coverage hole information performed by a RAN node.

[00023] Fig. 7 is schematic illustration of UEs travelling through a coverage hole of a cell.

[00024] Fig. 8 is a flow chart illustrating a method for handling coverage hole interruption for a UE in a wireless communication network, according to possible embodiments.

[00025] Fig. 9 is a block diagram illustrating a wireless device in more detail, according to further possible embodiments.

[00026] Fig. 10 is a block diagram illustrating a RAN node in more detail, according to further possible embodiments. Detailed Description

[00027] Fig. 2 shows a wireless communication network 100 comprising a RAN node 130 that is in, or is adapted for, wireless communication with a wireless device 140. The RAN node 130 provides wireless communication to wireless devices that are within a cell 150, i.e. a geographical area that can be reached by radio signals from the RAN node. In this cell 150 there may be one or more coverage holes 160, which are geographical areas within the cell 150 where there are bad radio coverage, for some reason.

[00028] The wireless communication network 100 may be any kind of wireless communication network that can provide radio access to wireless devices. Example of such wireless communication networks are Global System for Mobile communication (GSM), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA 2000), Long Term Evolution (LTE), LTE Advanced, Wireless Local Area Networks (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), WiMAX Advanced, as well as 5G wireless communication networks based on technology such as New Radio (NR).

[00029] The RAN node 130 may be any kind of network node that provides wireless access to a wireless device 140 alone or in combination with another network node. Examples of RAN nodes 130 are a base station (BS), a radio BS, a base transceiver station, a BS controller, a network controller, a Node B (NB), an evolved Node B (eNB), a NR BS, a Multi-cell/multicast Coordination Entity, a relay node, an access point (AP), a radio AP, a remote radio unit (RRU), a remote radio head (RRH) and a multi-standard BS (MSR BS).

[00030] The wireless device 140, aka wireless communication device may be any type of device capable of wirelessly communicating with a RAN node 130 using radio signals. For example, the wireless device 140 may be a User Equipment (UE), a machine type UE or a UE capable of machine to machine (M2M) communication, a sensor, a tablet, a mobile terminal, a smart phone, a laptop embedded equipped (LEE), a laptop mounted equipment (LME), a USB dongle, a Customer Premises Equipment (CPE) etc.

[00031] Fig. 3, in conjunction with fig. 2, describes a method performed by a wireless device 140 connected to a RAN node 130 handling a cell 150. The method comprises receiving 206, from the RAN node 130, information on geographical positions of a number of coverage holes 160 in the cell 150, and determining 210 that the wireless device 140 enters one of the number of coverage holes 160, based on a position of the wireless device 140, on information on quality of a signal from the RAN node being below a threshold and on the information on the geographical positions of the number of coverage holes 160. Further, the method comprises, in response to the determining 210, starting 212 a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

[00032] The wireless device 140 may receive the information on coverage holes when entering the cell, or when entering or approaching a coverage hole. A “coverage hole” signifies a geographical area within a cell, not just at the cell border, where signal quality of signals received from the RAN node is below a threshold. The threshold is set at a signal quality value at which the wireless device in the cell cannot decode information wirelessly received from the RAN node efficiently. The RAN node sets the signal quality value of the threshold. For example, the signal quality value threshold may be set at a value where the wireless device barely can decode a synchronization signal sent by the RAN node. As an alternative, the signal quality may be measured as RSRP, and the signal quality threshold may be a certain RSRP value. Settings of the second timer, such as the time of the second timer, aka time period or time duration of the second timer, may be preconfigured or received from the RAN node for example together with the information on the geographical positions of the coverage holes. During the running of the second timer, the wireless device stays in connected node, i.e. keeps wireless device configurations with the RAN node and wireless device buffers intact. The first timer may be the T310 timer described in connection with fig. 1. In other words, the first timer referred to above is a regular timer used when the wireless device loses radio coverage in a cell, which first timer is suitable when the wireless device for example leaves the cell. That the first timer for RLF triggering is used when losing radio coverage when not entering one of the number of coverage holes signifies that the first timer is used when quality at the wireless device of a signal from the RAN node goes below the threshold when outside of a coverage hole, for example when the UE crosses the cell border and moves towards another cell.

[00033] In this way, the wireless device would use a second timer when in a coverage hole, which time is longer than a time of a first timer, i.e. normal RLF timer used when losing coverage when not in a coverage hole. A longer timer means that the wireless device has a larger chance of leaving such a coverage hole before the timer has ended. And if the wireless device has left the coverage hole during the time of the second timer, the wireless device can then carry on communicating with the RAN node using the same communication resources such as radio bearers. In other words, with the above solution, the wireless device can avoid triggering RLF when it comes into a known coverage hole in the same cell. Further, the wireless device can resume exactly the same sessions as before the coverage hole. Also, the wireless device can avoid unnecessary cell searching during the coverage hole interruption time. As a result, a more time and resource efficient procedure is achieved for handling wireless devices that enters coverage holes within cells, compared to the prior art RLF procedure described in relation with fig. 1. The second timer may only be used when it is detected that the wireless device enters a coverage hole.

[00034] According to an embodiment, the method further comprises determining 207 that the wireless device 140 approaches one of the number of coverage holes 160, based on the position of the wireless device 140 and on the information on the geographical positions of the number of coverage holes 160. By determining that the wireless device approaches a coverage hole, the wireless device can prepare for the entering of the coverage hole, before the coverage hole is entered. [00035] According to a variant of this embodiment, the method further comprises sending 208, to the RAN node 130, information indicating that the wireless device 140 approaches one of the number of coverage holes. Hereby the RAN node is informed of the possible loss of connection with the wireless device and can plan for the wireless device being lost for up to the time of the second timer, and keeping the setting for the connections with the wireless device at least during the time of the second timer.

[00036] Further, the information sent 208 to the RAN node 130 that the wireless device (140) approaches one of the coverage holes comprises one or more of: which of the number of coverage holes the wireless device approaches, time left until the wireless device expects to go out of coverage, wireless device position, wireless device direction and wireless device speed. Such information could be useful for the RAN node in order to predict what may happen to the wireless device during the time of the second timer, e.g. based on statistics from other wireless devices that has travelled earlier through this coverage hole.

[00037] According to another embodiment, the determining 210 that the wireless device enters one of the number of coverage holes is also based on the moving direction of the wireless device, and possibly also on velocity of the wireless device. Further, according to another embodiment, the determining 207 that the wireless device approaches one of the number of coverage holes is also based on the moving direction of the wireless device, and possibly also on the velocity of the wireless device. By taking information as moving direction and speed/velocity into account, the wireless device can predict where it may end up after the time of the second timer. Also, it is possible for the wireless device to send such information to the RAN node so that the RAN node makes such predictions.

[00038] According to another embodiment, in response to the starting 212 of the second timer, the wireless device will not transmit any data or signals towards the RAN node until the time of the second timer has ended or until coverage hole interruption has ended. Hereby, wireless device battery is saved. [00039] According to another embodiment, the method further comprises receiving, from the RAN node, instructions for one or more of: settings of the second timer, configurations for sending 208, to the RAN node 130, of information indicating that the wireless device 140 enters or approaches one of the number of coverage holes, and configurations for sending of a connections ended message after the second timer has expired. Any of the settings or configurations mentioned may be received in advance, e.g. at the receiving of information of the geographical positions of the number of coverage holes. Alternatively, any of the settings or configurations (except for the configuration for sending information of the device approaching a coverage hole) may be received in response to the information sent to the RAN node 130 indicating that the wireless device 140 approaches one of the number of coverage holes. The configurations for sending of information that the device approaches a coverage hole and/or for sending of connection ended message may be configured grant resources to use for sending such information, contention free random access resources or scheduling request resources.

[00040] According to another embodiment, the method further comprises, in response to the starting 212 of the second timer, determining 216 signal quality of signals received from the RAN node, and, when the determined signal quality is above a threshold within the time of the second timer, sending 218 information to the RAN node 130 indicating that coverage hole interruption has ended, and when the determined signal quality is below the threshold at the end of the time of the second timer, triggering 220 release of the connection with the RAN node. This is one alternative how the wireless device can behave when in the coverage hole. As the wireless device stays in connected mode during the time of the second timer, i.e. keeps the connection configurations etc. with the RAN node, the RAN node can quickly resume communication with the RAN node when quality is good enough. Signal quality may be signal strength such as RSRP or a measure of whether the device is in synchronization. Triggering 220 release of the connection with the RAN node is what happens when triggering Radio Link Failure. Coverage hole interruption has ended here signifies that signal quality is sufficient for communication between the wireless device and the RAN node, i.e. the wireless device can hear the RAN node again.

[00041 ] According to another embodiment, at the end of the time of the second timer, sending information to the RAN node 130 indicating that coverage hole interruption has ended. As an alternative to the above embodiment, the wireless device may just wait for the second timer to end and then try to resume the connection at the end of the second timer by sending information that from the wireless device point of view, coverage hole interruption has ended. Depending on any response from the RAN node, the wireless device can draw a conclusion about possible future communication. This alternative is especially useful for example when information on the coverage hole has revealed that wireless devices that travelled through the coverage hole earlier, normally has good enough signal quality at the end of the second timer. For example, if there is a motorway going through a tunnel at this position. When only the regular short first timer is used, the wireless device may still be in the tunnel when the first timer ends.

[00042] According to another embodiment, the method further comprises receiving 222 an uplink grant message from the RAN node 130, in response to the sending 218 of the information to the RAN node indicating that coverage hole interruption has ended.

[00043] According to yet another embodiment as shown in fig. 4, the method further comprises, when a signal quality of a signal received from the RAN node 130 goes below a first coverage hole threshold, determining 201 a first coverage hole geographical position for the wireless device 140, and sending 202 the determined first geographical position to the RAN node 130. The method further comprises, when a signal quality of a signal received from the RAN node 130 goes above a second coverage hole threshold, determining 203 a second coverage hole geographical position for the wireless device 140, and sending 204 the determined second geographical position to the RAN node 130, thereby enabling the RAN node to determine the information on geographical positions of a number of coverage holes 160 in the cell based on the first and second geographical position that the RAN node receives 206. Hereby, and when many wireless devices send such information over time to the RAN node, information on cell coverage holes such as position can be built up at the RAN node. The second coverage hole threshold may be the same as the first coverage hole threshold. Or alternatively, to avoid toggling above and below a threshold when the device moves on the border of a coverage hole, the second coverage hole threshold is set higher than the first coverage hole threshold. Before those steps 201-204, the RAN node may have configured the wireless device to determine and send such information. That the signal quality goes below a first threshold and goes above a second threshold, respectively, may be determined from two or more consecutive signal quality measurements.

[00044] According to another embodiment, the sending 202, 204 of the first and/or the second geographical position also comprising sending to the RAN node 130 one or more of: type of wireless device, time of day, direction, speed, and altitude of wireless device. Such more detailed information can be used by the RAN node to determine more information on geographical positions of the coverage holes, such as when a certain geographical position is experienced as a coverage hole for one wireless device but not for another. An example could be a tunnel under a motorway for pedestrians where the geographical position of the intersection between the tunnel and the motorway would be a coverage hole for pedestrians walking but not for cars moving much faster on the motorway and in a different direction than the pedestrians.

[00045] Fig. 5, in conjunction with fig. 2, describes a method performed by a RAN node 130 of a wireless communication network 100, the RAN node handling a cell 150. The method comprises sending 306, to a wireless device 140 connected to the RAN node 130, information on geographical positions of a number of coverage holes 160 in the cell 150, and sending 308, to the wireless device 140, an instruction to stay in connected mode according to a time of a second timer for RLF triggering, when entering one of the number of coverage holes, the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes, thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

[00046] The information on geographical positions of coverage holes may be sent to the wireless device in response to the RAN node receiving information that the wireless device enters the cell. The instruction may be a short message that refers to actual instructions already stored at the wireless device. The instructions, either pre-stored or sent, comprise time settings of the second timer, and possibly also instructions for sending “interruption ended” messages by the wireless device. The interruption ended messages may be sent in a Contention Free Random Access, CFRA, and in that case CFRA resource configuration may also be sent.

[00047] According to an embodiment, the method further comprises receiving 310, from the wireless device 140, information that the wireless device approaches or enters one of the number of coverage holes.

[00048] According to an embodiment, the method further comprises receiving 312, from the wireless device 140 and after the sending 308 of the instruction, information indicating that coverage hole interruption has ended. The information indicating that coverage hole interruption has ended comprises information indicating to the RAN node that the wireless device 140 experiences a signal quality above a threshold, i.e. an OK signal quality to resume communication via the RAN node.

[00049] According to an alternative of this embodiment, the information indicating that coverage hole interruption has ended is received 312 when the wireless device experiences a signal quality of signals sent by the RAN node that is above a threshold during the time of the second timer.

[00050] According to another embodiment, the method further comprises sending 316 an uplink grant message to the wireless device 140, in response to the receiving 312 of the information indicating that coverage hole interruption has ended.

[00051] According to another embodiment, the method further comprises, in response to the receiving 310 of information that the wireless device 140 approaches or enters one of the number of coverage holes, stopping any transmission to the wireless device until receiving 312 information from the wireless device that coverage hole interruption has ended, and thereafter continuing transmission to the wireless device 140.

[00052] According to another embodiment, the method further comprises, when the wireless device experiences a signal quality of signals sent by the RAN node 130 that is below a threshold at the end of the time of the second timer, receiving 314 information of a release of the connection between the wireless device and the RAN node. Such information may be a RLF triggering message.

[00053] According to another embodiment, which is shown in fig. 6, and which is used in connection with the embodiments described in fig. 5, the method described in fig. 5 further comprises receiving 301 , from wireless devices connected to the RAN node 130, first geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node 130 goes below a first coverage hole threshold, and receiving 303, from wireless devices connected to the RAN node 130, second geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node 130 goes above a second coverage hole threshold. Further, the method comprises determining 305 the information on geographical positions of the number of coverage holes 160 in the cell 150 based on the received first and second geographical positions. This embodiment may be performed over a long time in order to collect enough statistics to achieve a good picture of the coverage holes, such as to create a map of the coverage holes in the cell.

[00054] According to an embodiment, the receiving 301 , 303 of first and second geographical positions further comprises receiving information on one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device, and wherein the determining 305 is also based on the information on the one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device. Such more detailed information can be used to determine when a certain geographical position is experienced as a coverage hole for one wireless device but not for another. An example could be a tunnel under a motorway for pedestrians where the geographical position of the intersection between the tunnel and the motorway would be a coverage hole for pedestrians walking but not for cars moving much faster on the motorway and in a different direction than the pedestrians.

[00055] In the following an embodiment of the invention is described. A coverage hole, CH, of a cell is in the simplest case defined by outer boundaries of an area with no coverage within the cell. The outer boundaries are defined by input from several UEs. According to an embodiment, each UE that enters a coverage hole provides both first geographical coordinates when losing connection and second geographical coordinates when re-connecting to the network. Two examples of such entering and exiting of a coverage hole 402 is shown in fig. 7. As seen here, UEA sends its geographical position data, e.g. coordinates UE_A, posi when entering the coverage hole 402 and when exiting the coverage hole 402, the UEA sends its geographical position data, e.g. coordinates UE_A, pos2 to its serving RAN node. In a similar manner, the UEB sends its coordinates UE_B, posi when entering the coverage hole and when exiting the coverage hole the UEB sends its coordinates UE_B pos2. In the example in fig. 7 UEA and UEB send also their respective altitude, which is optional. The UEs determine that they enter the coverage hole when the signal quality of signals from the RAN node of the respective UE drops below a threshold, such as when the UE loses synchronization or the RSRP drops below a threshold. The UEs determine that they exit the coverage hole when the signal quality of signals from the RAN node of the respective UE goes above the threshold again, for example when the RSRP of the respective UE is above the threshold again. The position data is used by the RAN node to build a CH map containing CHs so detected within its cell or cells. The size and shape of a CH is defined by the coverage hole outer boundary. It should be noted that the data or information of a coverage hole may also include e.g. type_of_device (car, smartphone, smartwatch etc.), time of day, which direction, speed and/or altitude with which the UE is entering or approaching the coverage hole. Using this more detailed input means that a certain geographical position may be a CH for a UE approaching from a certain direction at a certain speed, while the same geographical position may not be a CH for UEs approaching from a different direction at a different speed. An example of this could be a tunnel under a motorway for pedestrians. The geographical position of the intersection would be a CH for slow pedestrians walking through the tunnel but not for fast moving cars on the motorway.

[00056] Further, the RAN node may learn and dynamically update the area, shape and other attributes of the CH by continuous input of geographical position data from UEs entering and exiting CHs in the cell. Also, the RAN node may have a Machine Learning model that learns the area, size and shape of the coverage hole and continuously creates/updates the CH map using input from multiple UEs. Hence, the CH map may include information like CH boundaries (coordinates), type_of_device (car, smartphone, smartwatch etc.), time of day which direction, speed and/or altitude with which the UE is approaching the CH.

[00057] Further, and according to an embodiment, the RAN node may configure the UE to trigger measurement report (MR) events so that the UE reports any locations of coverage holes to the RAN node, when its signal quality drops below a threshold and also when the signal quality resumes above the threshold, see fig. 7. When such an MR event is triggered, the UE will send to the RAN node a specific coverage hole MR which contains information of where the hole is, e.g. GPS coordinates, and possibly also the direction and speed the UE had when approaching the coverage hole. This information can later be used by a UE to estimate if the UE enters or is about to enter a CH or not. Based on the coverage hole MRs received from several UEs over time, the RAN node can build the CH map. Also, the RAN node can define new CH triggering events based on UE position, and possibly also speed and direction, which indicate when a UE is about to enter a CH. This map/events are constructed per cell and can be sent to the UE as part of the System Information Block (SIB) or be sent as part of or in conjunction with hand-over command, cell re-configuration, or dedicated signaling.

[00058] Fig. 8 describes an embodiment for a UE to avoid RLF when entering CFIs in a NR-based network. Flowever, the embodiment is equally useable in any other kind of network. After a UE has entered 502 a cell, the UE receives 504 information on geographical positions of CFIs in the cell, such as a CFI map. In addition to the information on geographical positions of CFIs, the UE can also receive from the gNB instructions aka configurations to use when entering or approaching a CFI. These instructions, which may be called Coverage hole event information, may contain timer values, Configured grant configuration for CFI warning and “out of hole” indication.

[00059] When the UE enters or approaches 506 a known CFI, determined based on UE position and/or signal quality below a threshold compared to the information on geographical positions of CFIs, and possibly also predicted route of the UE, a CFI warning is triggered 508, indicating that the UE is approaching the known CFI, and sent to the gNB. The CFI warning may be transmitted on Configured Grant resources or it may use a dynamic Grant. The CFI warning message does not need to contain any specific information except that it needs to indicate to the gNB that the UE is approaching a CFI and expects to be out-of-coverage soon. The message could potentially contain more information such as which CFI the UE is approaching and time left until the UE expects to go out-of-coverage. This information could also be conveyed to the gNB by sending of the position, direction and possibly also speed of the UE. The CFI warning message could be a new Radio Resource Control (RRC) message or a new Media Access Control (MAC) Control Element (CE).

[00060] According to an embodiment, the gNB may respond to the CFI warning by sending 510 a “Connection interrupt” message to the UE. The Connection Interrupt message may contain configuration settings, such as second timer setting for triggering RLF when in a CFI and Configured Grant configurations for transmission of an “interruption ended” message, if such configuration settings have not already been sent. The “interruption ended” message (see step 518) is used to by the UE to indicate to the gNB that it has left the CH, i.e. that the signal quality, e.g. RSRP, is above a threshold (step 516). The information in the “Connection interrupt” message could also be carried by a separate CH event information message. Further, a CFRA resource configuration may also be included in the “Connection interrupt” message. The CFRA could alternatively be used for the “interruption ended” message. This information may not be carried by the CH event information message due to the high use of CFRA resources. Alternatively, the Connection interrupt message could be a new RRC message, preferably if it contains CFRA configuration, or a new MAC CE.

[00061] Further, when receiving the CH warning message 508 from the UE, the gNB may stop 512 any downlink (DL) transmission of data to the UE. Alternatively, the gNB may continue DL transmissions to the UE after receiving the CH warning message, as long as the gNB receives Hybrid Automatic Repeat Request (HARQ) acknowledgements from the UE.

[00062] Further, when having entered the CH 506, the UE starts 514 the second RLF timer, aka “CH timer”, and continues to measure RSRP on the serving cell. While the CH timer is running, the UE does not trigger RLF, the UE does not need to resynchronize and the UE buffers are kept. If the signal quality reaches 516 a threshold, e.g. RSRP above a threshold or there are N consecutive "in sync" indications, while the second timer is running, the UE triggers and sends 518 the “interruption ended” message to the gNB. The “interruption ended” message may contain a Buffer Status Report (BSR) that indicates how much data the UE has in its uplink buffer. If the CH timer expires 522 and the signal quality threshold has not been reached, the UE triggers 524 RLF.

[00063] Upon reception of the “interruption ended” message 518, the gNB continues or resumes 520 transmissions to the UE. The transmissions to the UE may contain new uplink (UL) grants. The “interruption ended” message from the UE does not need to contain any specific information except that it needs to indicate that the UE has left the coverage hole and is now within radio coverage. The “interruption ended message” could be a new RRC or a new MAC CE message.

[00064] Fig. 9, in conjunction with fig. 2, describes a wireless device 140 operable to be connected to a RAN node 130 handling a cell 150. The wireless device 140 comprises a processing circuitry 603 and a memory 604. Said memory contains instructions executable by said processing circuitry, whereby the wireless device 140 is operative for: receiving, from the RAN node 130, information on geographical positions of a number of coverage holes 160 in the cell 150, determining that the wireless device 140 enters one of the number of coverage holes 160, based on: a position of the wireless device 140; information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes 160; and in response to the determining, starting a second timer for RLF triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

[00065] According to an embodiment, the wireless device 140 is further operative for determining that the wireless device 140 approaches one of the number of coverage holes 160, based on the position of the wireless device 140 and on the information on the geographical positions of the number of coverage holes 160, and sending, to the RAN node 130, information indicating that the wireless device 140 approaches one of the number of coverage holes.

[00066] According to another embodiment, the wireless device 140 is operative for the determining that the wireless device approaches one of the number of coverage holes also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

[00067] According to another embodiment, the information sent to the RAN node 130 that the wireless device 140 approaches one of the coverage holes comprises one or more of: which of the number of coverage holes the wireless device approaches, time left until the wireless device expects to go out of coverage, wireless device position, wireless device direction and wireless device speed.

[00068] According to yet another embodiment, the wireless device 140 is operative for the determining that the wireless device enters one of the number of coverage holes also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

[00069] According to yet another embodiment, the wireless device is further operative for, in response to the starting of the second timer, not transmitting any data or signals towards the RAN node until the time of the second timer has ended or until coverage hole interruption has ended.

[00070] According to still another embodiment, the wireless device 140 is further operative for: receiving, from the RAN node, instructions for one or more of: settings of the second timer, configurations for sending, to the RAN node 130, of information indicating that the wireless device 140 enters or approaches one of the number of coverage holes, and configurations for sending of a connections ended message after the second timer has expired.

[00071] According to still another embodiment, the wireless device 140 is further operative for: in response to the starting of the second timer, determining signal quality of signals received from the RAN node, and, when the determined signal quality is above a threshold within the time of the second timer, sending information to the RAN node 130 indicating that coverage hole interruption has ended, and when the determined signal quality is below the threshold at the end of the time of the second timer, triggering release of the connection with the RAN node.

[00072] According to another embodiment, the wireless device 140 is further operative for, at the end of the time of the second timer, sending information to the RAN node 130 indicating that coverage hole interruption has ended.

[00073] According to another embodiment, the wireless device 140 is further being operative for receiving an uplink grant message from the RAN node 130, in response to the sending of the information to the RAN node indicating that coverage hole interruption has ended.

[00074] According to yet another embodiment, the wireless device 140 is further operative for, when a signal quality of a signal received from the RAN node 130 goes below a first coverage hole threshold, determining a first coverage hole geographical position for the wireless device 140, and sending the determined first geographical position to the RAN node 130. Further, the wireless device 140 is operative for, when a signal quality of a signal received from the RAN node 130 goes above a second coverage hole threshold, determining a second coverage hole geographical position for the wireless device, and sending the determined second geographical position to the RAN node 130, thereby enabling the RAN node to determine the information on geographical positions of a number of coverage holes 160 in the cell based on the first and second geographical position that the RAN node receives.

[00075] According to a variant of the latest embodiment, the wireless device 140 is operative for the sending of the first and/or the second geographical position by also sending to the RAN node 130 one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

[00076] According to other embodiments, the wireless device 140 may further comprise a communication unit 602, which may be considered to comprise conventional means for wireless communication with the RAN node 130, such as a transceiver for wireless transmission and reception of signals to/from RAN nodes in the communication network. The instructions executable by said processing circuitry 603 may be arranged as a computer program 605 stored e.g. in said memory 604. The processing circuitry 603 and the memory 604 may be arranged in a sub-arrangement 601. The sub-arrangement 601 may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device,

PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing circuitry 603 may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions. The wireless device 140 may also comprise a battery 606 that provides power to the device.

[00077] The computer program 605 may be arranged such that when its instructions are run in the processing circuitry, they cause the wireless device 140 to perform the steps described in any of the described embodiments of the wireless device 140 and its method. The computer program 605 may be carried by a computer program product connectable to the processing circuitry 603. The computer program product may be the memory 604, or at least arranged in the memory. The memory 604 may be realized as for example a RAM (Random- access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). Further, the computer program 605 may be carried by a separate computer-readable medium, such as a CD, DVD or flash memory, from which the program could be downloaded into the memory 604. Alternatively, the computer program may be stored on a server or any other entity to which the wireless device 140 has access via the communication unit 602. The computer program 605 may then be downloaded from the server into the memory 604.

[00078] Fig. 10, in conjunction with fig. 2, describes a RAN node 130 operable in a wireless communication network 100 for handling a cell 150. The RAN node 130 comprises a processing circuitry 703 and a memory 704. Said memory contains instructions executable by said processing circuitry, whereby the RAN node 130 is operative for sending, to a wireless device 140 connected to the RAN node 130, information on geographical positions of a number of coverage holes 160 in the cell 150, and sending, to the wireless device 140, an instruction to stay in connected mode according to a time of a second timer for RLF triggering, when entering one of the number of coverage holes 160, the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes 160, thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole. [00079] According to an embodiment, the RAN node 130 is further operative for receiving, from the wireless device 140, information that the wireless device approaches or enters one of the number of coverage holes.

[00080] According to another embodiment, the RAN node 130 is further operative for receiving, from the wireless device 140 and after the sending of the instruction, information indicating that coverage hole interruption has ended.

[00081 ] According to another embodiment, the RAN node 130 is operative for the receiving of the information indicating that coverage hole interruption has ended when the wireless device experiences a signal quality of signals sent by the RAN node that is above a threshold during the time of the second timer.

[00082] According to yet another embodiment, the RAN node 130 is further operative for sending an uplink grant message to the wireless device 140, in response to the receiving of the information indicating that coverage hole interruption has ended.

[00083] According to yet another embodiment, the RAN node 130 is further operative for, in response to the receiving of information that the wireless device 140 approaches or enters one of the number of coverage holes, stopping any transmission to the wireless device until receiving information from the wireless device that coverage hole interruption has ended, and thereafter continuing transmission to the wireless device 140.

[00084] According to still another embodiment, the RAN node 130 is further operative for, when the wireless device experiences a signal quality of signals sent by the RAN node 130 that is below a threshold at the end of the time of the second timer, receiving information of a release of the connection between the wireless device and the RAN node.

[00085] According to another embodiment, the RAN node 130 is further operative for receiving, from wireless devices connected to the RAN node 130, first geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node 130 goes below a first coverage hole threshold, and receiving, from wireless devices connected to the RAN node 130, second geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node 130 goes above a second coverage hole threshold. The RAN node 130 is further operative for determining the information on geographical positions of a number of coverage holes 160 in the cell 150 based on the received first and second geographical positions.

[00086] According to a variant of the latest embodiment, the RAN node is operative for the receiving of the first and second geographical positions by receiving information on one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device. Further, the RAN node is operative for the determining of the information on geographical positions also based on the information on the one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

[00087] According to other embodiments, the RAN node 130 may further comprise a communication unit 702, which may be considered to comprise conventional means for wireless communication with the wireless device 140, such as a transceiver for wireless transmission and reception of signals to/from nodes in the communication network. The communication unit 702 may also comprise conventional means for communication with other RAN nodes of the wireless communication network 100. The instructions executable by said processing circuitry 703 may be arranged as a computer program 705 stored e.g. in said memory 704. The processing circuitry 703 and the memory 704 may be arranged in a sub-arrangement 701. The sub-arrangement 701 may be a micro processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing circuitry 703 may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions. [00088] The computer program 705 may be arranged such that when its instructions are run in the processing circuitry, they cause the RAN node 130 to perform the steps described in any of the described embodiments of RAN node 130 and its method. The computer program 705 may be carried by a computer program product connectable to the processing circuitry 703. The computer program product may be the memory 704, or at least arranged in the memory. The memory 704 may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). Further, the computer program 705 may be carried by a separate computer-readable medium, such as a CD, DVD or flash memory, from which the program could be downloaded into the memory 704. Alternatively, the computer program may be stored on a server or any other entity to which the RAN node 130 has access via the communication unit 702. The computer program 705 may then be downloaded from the server into the memory 704.

[00089] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the above- described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

1. A method performed by a wireless device (140) connected to a radio access network, RAN, node (130) handling a cell (150), the method comprising: receiving (206), from the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), determining (210) that the wireless device (140) enters one of the number of coverage holes (160), based on: a position of the wireless device (140); information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes (160); and in response to the determining (210), starting (212) a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

2. Method according to claim 1 , further comprising: determining (207) that the wireless device (140) approaches one of the number of coverage holes (160), based on the position of the wireless device (140) and on the information on the geographical positions of the number of coverage holes (160), and sending (208), to the RAN node (130), information indicating that the wireless device (140) approaches one of the number of coverage holes.

3. Method according to claim 2, wherein the determining (207) that the wireless device approaches one of the number of coverage holes is also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

4. Method according to claim 2 or 3, wherein the information sent (208) to the RAN node (130) that the wireless device (140) approaches one of the coverage holes comprises one or more of: which of the number of coverage holes the wireless device approaches, time left until the wireless device expects to go out of coverage, wireless device position, wireless device direction and wireless device speed.

5. Method according to any of the preceding claims, wherein the determining (210) that the wireless device enters one of the number of coverage holes is also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

6. Method according to any of the preceding claims, in response to the starting (212) of the second timer, not transmitting any data or signals towards the RAN node until the time of the second timer has ended or until coverage hole interruption has ended.

7. Method according to any of the preceding claims, further comprising: receiving, from the RAN node, instructions for one or more of: settings of the second timer, configurations for sending (208), to the RAN node (130), of information indicating that the wireless device (140) enters or approaches one of the number of coverage holes, and configurations for sending of a connections ended message after the second timer has expired.

8. Method according to any of the preceding claims, further comprising: in response to the starting (212) of the second timer, determining (216) signal quality of signals received from the RAN node, and, when the determined signal quality is above a threshold within the time of the second timer, sending (218) information to the RAN node (130) indicating that coverage hole interruption has ended, and when the determined signal quality is below the threshold at the end of the time of the second timer, triggering (220) release of the connection with the RAN node.

9. Method according to any of claims 1 -7, at the end of the time of the second timer, sending information to the RAN node (130) indicating that coverage hole interruption has ended.

10. Method according to claim 8 or 9, further comprising: receiving (222) an uplink grant message from the RAN node (130), in response to the sending (218) of the information to the RAN node indicating that coverage hole interruption has ended.

11. Method according to any of the preceding claims, further comprising: when a signal quality of a signal received from the RAN node (130) goes below a first coverage hole threshold, determining (201) a first coverage hole geographical position for the wireless device (140), sending (202) the determined first geographical position to the RAN node (130), when a signal quality of a signal received from the RAN node(130) goes above a second coverage hole threshold, determining (203) a second coverage hole geographical position for the wireless device (140), and sending (204) the determined second geographical position to the RAN node (130), thereby enabling the RAN node to determine the information on geographical positions of a number of coverage holes (160) in the cell based on the first and second geographical position that the RAN node receives (206).

12. Method according to claim 11 , wherein the sending (202, 204) of the first and/or the second geographical position also comprising sending to the RAN node (130) one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

13. A method performed by a Radio access network, RAN, node (130) of a wireless communication network (100), the RAN node handling a cell (150), the method comprising: sending (306), to a wireless device (140) connected to the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), and sending (308), to the wireless device (140), an instruction to stay in connected mode according to a time of a second timer for radio link failure, RLF, triggering, when entering one of the number of coverage holes (160), the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes (160), thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

14. Method according to claim 13, further comprising: receiving (310), from the wireless device (140), information that the wireless device approaches or enters one of the number of coverage holes.

15. Method according to any of claims 13-14, further comprising: receiving (312), from the wireless device (140) and after the sending (308) of the instruction, information indicating that coverage hole interruption has ended.

16. Method according to claim 15, wherein the information indicating that coverage hole interruption has ended is received (312) when the wireless device experiences a signal quality of signals sent by the RAN node that is above a threshold during the time of the second timer.

17. Method according to claim 15 or 16, further comprising: sending (316) an uplink grant message to the wireless device (140), in response to the receiving (312) of the information indicating that coverage hole interruption has ended.

18. Method according to any of claims 14-17, further comprising, in response to the receiving (310) of information that the wireless device (140) approaches or enters one of the number of coverage holes, stopping any transmission to the wireless device until receiving (312) information from the wireless device that coverage hole interruption has ended, and thereafter continuing transmission to the wireless device (140).

19. Method according to claim 13 or 14 further comprising, when the wireless device experiences a signal quality of signals sent by the RAN node (130) that is below a threshold at the end of the time of the second timer, receiving (314) information of a release of the connection between the wireless device and the RAN node.

20. Method according to any of claims 13-19, further comprising: receiving (301), from wireless devices connected to the RAN node (130), first geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node (130) goes below a first coverage hole threshold, receiving (303), from wireless devices connected to the RAN node (130), second geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node (130) goes above a second coverage hole threshold, and determining (305) the information on geographical positions of a number of coverage holes (160) in the cell (150) based on the received first and second geographical positions.

21. Method according to claim 20, wherein the receiving (301 , 303) of first and second geographical positions further comprises receiving information on one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device, and wherein the determining (305) is also based on the information on one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

22. A wireless device (140) operable to be connected to a RAN node (130) handling a cell (150), the wireless device (140) comprising a processing circuitry (603) and a memory (604), said memory containing instructions executable by said processing circuitry, whereby the wireless device (140) is operative for: receiving, from the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), determining that the wireless device (140) enters one of the number of coverage holes (160), based on: a position of the wireless device (140); information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes (160); and in response to the determining, starting a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

23. Wireless device (140) according to claim 22, further being operative for: determining that the wireless device (140) approaches one of the number of coverage holes (160), based on the position of the wireless device (140) and on the information on the geographical positions of the number of coverage holes (160), and sending, to the RAN node (130), information indicating that the wireless device (140) approaches one of the number of coverage holes.

24. Wireless device (140) according to claim 23, operative for the determining that the wireless device approaches one of the number of coverage holes also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

25. Wireless device (140) according to claim 23 or 24, wherein the information sent to the RAN node (130) that the wireless device (140) approaches one of the coverage holes comprises one or more of: which of the number of coverage holes the wireless device approaches, time left until the wireless device expects to go out of coverage, wireless device position, wireless device direction and wireless device speed.

26. Wireless device (140) according to any of claims 22-25, operative for the determining that the wireless device enters one of the number of coverage holes also based on moving direction of the wireless device, and possibly also on velocity of the wireless device.

27. Wireless device (140) according to any of claims 22-26, further being operative for, in response to the starting of the second timer, not transmitting any data or signals towards the RAN node until the time of the second timer has ended or until coverage hole interruption has ended.

28. Wireless device (140) according to any of claims 22-27, further being operative for: receiving, from the RAN node, instructions for one or more of: settings of the second timer, configurations for sending, to the RAN node (130), of information indicating that the wireless device (140) enters or approaches one of the number of coverage holes, and configurations for sending of a connections ended message after the second timer has expired.

29. Wireless device (140) according to any of claims 22-28, further being operative for: in response to the starting of the second timer, determining signal quality of signals received from the RAN node, and, when the determined signal quality is above a threshold within the time of the second timer, sending information to the RAN node (130) indicating that coverage hole interruption has ended, and when the determined signal quality is below the threshold at the end of the time of the second timer, triggering release of the connection with the RAN node.

30. Wireless device (140) according to any of claims 22-28, further being operative for, at the end of the time of the second timer, sending information to the RAN node (130) indicating that coverage hole interruption has ended.

31. Wireless device (140) according to claim 29 or 30, further being operative for: receiving an uplink grant message from the RAN node (130), in response to the sending of the information to the RAN node indicating that coverage hole interruption has ended.

32. Wireless device (140) according to any of claims 22-31 , further being operative for: when a signal quality of a signal received from the RAN node (130) goes below a first coverage hole threshold, determining a first coverage hole geographical position for the wireless device (140), sending the determined first geographical position to the RAN node

(130), when a signal quality of a signal received from the RAN node(130) goes above a second coverage hole threshold, determining a second coverage hole geographical position for the wireless device, and sending the determined second geographical position to the RAN node (130), thereby enabling the RAN node to determine the information on geographical positions of a number of coverage holes (160) in the cell based on the first and second geographical position that the RAN node receives.

33. Wireless device (140) according to claim 32, operative for the sending of the first and/or the second geographical position by also sending to the RAN node (130) one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

34. A RAN node (130) operable in a wireless communication network (100) for handling a cell (150), the RAN node (130) comprising a processing circuitry (703) and a memory (704), said memory containing instructions executable by said processing circuitry, whereby the RAN node (130) is operative for: sending, to a wireless device (140) connected to the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), and sending, to the wireless device (140), an instruction to stay in connected mode according to a time of a second timer for radio link failure, RLF, triggering, when entering one of the number of coverage holes (160), the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes (160), thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

35. RAN node (130) according to claim 34, further being operative for: receiving, from the wireless device (140), information that the wireless device approaches or enters one of the number of coverage holes.

36. RAN node (130) according to claim 34 or 35, further being operative for: receiving, from the wireless device (140) and after the sending of the instruction, information indicating that coverage hole interruption has ended.

37. RAN node (130) according to claim 36, being operative for the receiving of the information indicating that coverage hole interruption has ended when the wireless device experiences a signal quality of signals sent by the RAN node that is above a threshold during the time of the second timer.

38. RAN node (130) according to claim 36 or 37, further being operative for sending an uplink grant message to the wireless device (140), in response to the receiving of the information indicating that coverage hole interruption has ended.

39. RAN node (130) according to any of claims 35-38, further being operative for, in response to the receiving of information that the wireless device (140) approaches or enters one of the number of coverage holes, stopping any transmission to the wireless device until receiving information from the wireless device that coverage hole interruption has ended, and thereafter continuing transmission to the wireless device (140).

40. RAN node (130) according to claim 34 or 35, further being operative for, when the wireless device experiences a signal quality of signals sent by the RAN node (130) that is below a threshold at the end of the time of the second timer, receiving information of a release of the connection between the wireless device and the RAN node. 41. RAN node (130) according to any of claims 34-40, further being operative for: receiving, from wireless devices connected to the RAN node (130), first geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node (130) goes below a first coverage hole threshold, receiving, from wireless devices connected to the RAN node (130), second geographical positions of the wireless devices when a signal quality of a signal received by the respective wireless device from the RAN node (130) goes above a second coverage hole threshold, and determining the information on geographical positions of a number of coverage holes (160) in the cell (150) based on the received first and second geographical positions.

42. RAN node (130) according to claim 41 , operative for the receiving of the first and second geographical positions by receiving information on one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device, and wherein the RAN node is operative for the determining of the information on geographical positions also based on the information on the one or more of: type of wireless device, time of day, direction, speed, and altitude of the wireless device.

43. A computer program (605) comprising instructions, which, when executed by at least one processing circuitry (603) of a wireless device (140) configured for connection to a RAN node (130) handling a cell (150), causes the wireless device (140) to perform the following steps: receiving, from the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), determining that the wireless device (140) enters one of the number of coverage holes (160), based on: a position of the wireless device (140); information on quality of a signal from the RAN node being below a threshold; and the information on the geographical positions of the number of coverage holes (160); and in response to the determining, starting a second timer for radio link failure, RLF, triggering, a time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes.

44. A carrier containing the computer program (605) according to claim 43, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

45. A computer program (705) comprising instructions, which, when executed by at least one processing circuitry (703) of a RAN node (130) operable in a wireless communication network (100) for handling a cell (150), causes the RAN node (130) to perform the following steps: sending, to a wireless device (140) connected to the RAN node (130), information on geographical positions of a number of coverage holes (160) in the cell (150), and sending, to the wireless device (140), an instruction to stay in connected mode according to a time of a second timer for radio link failure, RLF, triggering, when entering one of the number of coverage holes (160), the time of the second timer being longer than a time of a first timer for RLF triggering used when losing radio coverage when not entering one of the number of coverage holes (160), thereby enabling the wireless device to stay in connected mode with the RAN node for a longer time when losing radio coverage when entering a coverage hole than when losing radio coverage when not entering a coverage hole.

46. A carrier containing the computer program (705) according to claim 45, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.