WO2021051406A1

WO2021051406A1 - Failure detection in wireless system

Info

Publication number: WO2021051406A1
Application number: PCT/CN2019/107076
Authority: WO
Inventors: Samuli Turtinen; Chunli Wu
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-09-20
Filing date: 2019-09-20
Publication date: 2021-03-25
Also published as: CN114287167B; CN114287167A

Abstract

This document discloses a solution for detecting communication failures. According to an aspect, a method comprises: detecting a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer; while the failure count timer is running, if a new communication failure indication is detected, omitting incrementing the failure counter; after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected, incrementing the failure counter; in response to the failure counter reaching a determined count value, triggering reporting of communication failure; and in response to reporting the communication failure, receiving a message comprising an operating parameter.

Description

FAILURE DETECTION IN WIRELESS SYSTEM

Field

Various embodiments described herein relate to the field of wireless communications and, particularly, to detecting a failure in a wireless system.

Background

Wireless networks operating on licensed frequency bands expand their operation to an unlicensed spectrum. Other wireless networks operate mainly or only on the unlicensed frequencies. Regulations have been designed for the unlicensed spectrum usage to ensure fair spectrum use across various spectrum users. Occupation of the unlicensed spectrum is inherently uncoordinated across the networks and provide a larger degree of unpredictability to the operation and performance, making the provision of certain services challenging. For example, any device of any wireless system may access a channel at any time.

In wireless networks, operational failures occur from time to time. The failures may relate to poor link quality, channel access problems, or device failures. Detection and reporting of such failures may be used to adjust operational parameters of one or more devices of a wireless network.

Brief description

Some aspects of the invention are defined by the independent claims.

Some embodiments of the invention are defined in the dependent claims.

The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. Some aspects of the disclosure are defined by the independent claims.

According to an aspect, there is provided an apparatus comprising means for performing: detecting a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer; while the failure count timer is running, if a new communication failure indication is detected, omitting incrementing the failure counter; after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected, incrementing the failure counter; in response to the failure counter reaching a determined count value , triggering reporting of communication failure; and in response to reporting the communication failure, receiving a message comprising an operating parameter.

In an embodiment, the means are configured to start of restart the failure count timer as a response to detecting the new communication failure indication after the expiry of the failure count timer.

In an embodiment, the means are configured to start, as a response to said detecting the first communication failure indication, a failure detection timer for counting a number of communication failure indications within a determined time interval.

In an embodiment, the means are configured to trigger the reporting of the communication failure, if the failure counter reaches the determined count value while the failure detection timer is running.

In an embodiment, the means are configured to reset the failure counter in response to expiry of the failure detection timer.

In an embodiment, the means are configured to restart the failure detection timer upon detecting a new communication failure indication while the failure count timer is not running.

In an embodiment, the means are configured to restart the failure detection timer upon detecting any new communication failure indication.

In an embodiment, any one of the communication failure indications is based on a failure in uplink transmission of at least one of the following uplink messages: an acknowledgment/negative acknowledgment message, a channel state indication report, a scheduling request, a random access message, payload data, a physical uplink shared channel transmission, a physical uplink control channel transmission, and a configured grant transmission.

In an embodiment, the communication failure indication is a failure in transmitting an uplink message according to a listen-before-talk procedure where the apparatus performs channel access only upon detecting, in a clear-channel assessment, a channel to have been idle for a determined time interval.

In an embodiment, the communication failure indication is a failure in a radio beam directed by using beamforming techniques.

In an embodiment, the means comprises: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

According to an aspect, there is provided a method comprising: detecting, by a wireless device, a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer; while the failure count timer is running, if a new communication failure indication is detected by the wireless device, omitting incrementing the failure counter; after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected by the wireless device, incrementing the failure counter; in response to the failure counter reaching a determined count value, triggering by the wireless device reporting of communication failure; and in response to reporting the communication failure, receiving by the wireless device a message comprising an operating parameter.

In an embodiment, the wireless device starts or restarts failure count timer as a response to detecting the new communication failure indication after the expiry of the failure count timer.

In an embodiment, the wireless device starts, as a response to said detecting the first communication failure indication, a failure detection timer for counting a number of communication failure indications within a determined time interval.

In an embodiment, the wireless device triggers the reporting of the communication failure, if the failure counter reaches the determined count value while the failure detection timer is running.

In an embodiment, the wireless device resets the failure counter in response to expiry of the failure detection timer.

In an embodiment, the wireless device restarts the failure detection timer upon detecting a new communication failure indication while the failure count timer is not running.

In an embodiment, the wireless device restarts the failure detection timer upon detecting any new communication failure indication.

In an embodiment, the communication failure indication is a failure in transmitting an uplink message according to a listen-before-talk procedure where the wireless device performs channel access only upon detecting, in a clear-channel assessment, a channel to have been idle for a determined time interval.

According to an aspect, there is provided a computer program product embodied on a computer-readable medium and comprising a computer program code readable by a computer, wherein the computer program code configures the computer to carry out a computer process comprising: detecting a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer; while the failure count timer is running, if a new communication failure indication is detected, omitting incrementing the failure counter; after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected, incrementing the failure counter; in response to the failure counter reaching a determined count value, triggering reporting of communication failure; and in response to reporting the communication failure, receiving a message comprising an operating parameter.

List of drawings

Embodiments are described below, by way of example only, with reference to the accompanying drawings, in which

Figure 1 illustrates a wireless communication scenario to which some embodiments of the invention may be applied;

Figure 2 illustrates an embodiment of a process for detecting communication failures;

Figures 3, 4A, and 4B illustrate some embodiments of the process of Figure 2;

Figures 5 and 6 illustrate operation of the embodiments of the invention in a case of various communication failure scenarios;

Figure 7 illustrates a procedure for stopping or resetting at least one timer upon detecting a successful listen-before-talk-transmission; and

Figure 8 illustrates a block diagram of a structure of an apparatus according to an embodiment of the invention.

Description of embodiments

The following embodiments are examples. Although the specification may refer to “an” , “one” , or “some” embodiment (s) in several locations, this does not necessarily mean that each such reference is to the same embodiment (s) , or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may contain also features/structures that have not been specifically mentioned.

In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G) , without restricting the embodiments to such an architecture, however. A person skilled in the art will realize that the embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN) , long term evolution (LTE, the same as E-UTRA) , wireless local area network (WLAN or WiFi) , worldwide interoperability for microwave access (WiMAX) ,

personal communications services (PCS) ,

wideband code division multiple access (WCDMA) , systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

Figure 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in Figure 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in Figure 1.

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

The example of Figure 1 shows a part of an exemplifying radio access network.

Figure 1 shows terminal devices or

user devices

100 and 102 configured to be in a wireless connection on one or more communication channels in a cell with an access node (such as (e/g) NodeB) 104 providing the cell. (e/g) NodeB refers to an eNodeB or a gNodeB, as defined in 3GPP specifications. The physical link from a user device to a (e/g) NodeB is called uplink or reverse link and the physical link from the (e/g) NodeB to the user device is called downlink or forward link. It should be appreciated that (e/g) NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communications system typically comprises more than one (e/g) NodeB in which case the (e/g) NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used not only for signalling purposes but also for routing data from one (e/g) NodeB to another. The (e/g) NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point, an access node, a relay station, an integrated access backhaul node, or any other type of interfacing device capable of operating in a wireless environment. The (e/g) NodeB includes or is coupled to transceivers. From the transceivers of the (e/g) NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g) NodeB may be further connected to core network 110 (CN or next generation core NGC) . Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets) , packet data network gateway (P-GW) , for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME) , etc.

The user device (also called UE, user equipment, user terminal, terminal device, etc. ) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station.

The user device typically refers to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM) , including, but not limited to, the following types of devices: a station (STA) , a mobile station (mobile phone) , smartphone, personal digital assistant (PDA) , handset, device using a wireless modem (alarm or measurement device, etc. ) , laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A user device may also be a device having capability to operate in Internet of Things (IoT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The user device may also utilise cloud. In some applications, a user device may comprise a small portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation is carried out in the cloud. The user device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses.

Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities) . CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc. ) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in Figure 1) may be implemented.

5G enables using multiple input –multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept) , including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC) , including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, cmWave and mmWave, and also being capable of being integrated with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6GHz –cmWave, below 6GHz –cmWave –mmWave) . One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

The current architecture in LTE networks is fully distributed in the radio and typically fully centralized in the core network. The low-latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC) . 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical) , critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications) .

The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 112, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in Figure 1 by “cloud” 114) . The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

Edge cloud may be brought into radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN) . Using edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 104) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 108) .

It should also be understood that the distribution of functions between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or node B (gNB) . It should be appreciated that MEC can be applied in 4G networks as well.

5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway, maritime, and/or aeronautical communications. Satellite communication may utilise geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano) satellites are deployed) . Each satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node 104 or by a gNB located on-ground or in a satellite.

It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g) NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g) NodeBs or may be a Home (e/g) nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto-or picocells. The (e/g) NodeBs of Figure 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e/g) NodeBs are required to provide such a network structure.

For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e/g) NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e/g) Node Bs, includes, in addition to Home (e/g) NodeBs (H (e/g) nodeBs) , a home node B gateway, or HNB-GW (not shown in Figure 1) . A HNB Gateway (HNB-GW) , which is typically installed within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

The access node 104 may be configured to operate on an unlicensed frequency bands and to establish frequency channels for frame transmissions on the unlicensed bands. Transmissions on the unlicensed bands may be based on first sensing the channel and, upon detecting the channel to be idle, carrying out frame transmission. This scheme is called Listen Before Talk (LBT) . Some IEEE 802.11 networks employ channel contention based on carrier sense multiple access with collision avoidance (CSMA/CA) for channel access. Every device attempting to gain a transmission opportunity (TXOP) is reducing a backoff value while the primary channel is sensed to be idle for a certain time interval. The backoff value may be selected randomly within a range defined by a contention window parameter. The contention window may have different ranges for different types of traffic, thus affecting priority of the different types of traffic. The channel sensing may be based on sensing a level of radio energy in the radio channel. The sensed level may be compared with a threshold: if the sensed level is below the threshold level, the channel may be determined to be idle (otherwise busy) . Such a procedure is called clear channel assessment (CCA) in 802.11 specifications. When the backoff value reaches zero, the STA gains the TXOP and starts frame transmission. If another STA gains the TXOP before that, the backoff value computation may be suspended, and the STA continues the backoff computation after the TXOP of the other STA has ended and the primary channel is sensed to be idle. The time duration (the backoff value) may not be decremented during the TXOP of the other STA, but the time duration that already lapsed before the suspension may be maintained, which means that the device now has a higher probability of gaining the TXOP. Other wireless networks such as the LTE may employ a similar but to some degree different CSMA or CCA procedure. Upon acquiring the TXOP by a STA, the STA may carry out frame transmissions for a determined time interval defined by a channel occupancy time (COT) . The COT may have a fixed value or a dynamic value adapted on the basis of some criteria. Some embodiments for the adaptation are described below.

The CCA is an example of the LBT procedure. Other communication systems may employ other types of LBT procedures. For example, the LTE specifications define another example of the LBT procedure. A common factor to the LBT procedures is that, before starting transmissions on an operating channel, a device may be required to perform the CCA. The equipment may observe the operating channel (s) for the duration of a CCA observation time. This may be at least 20 microseconds. The operating channel is considered occupied if an energy level sensed in the channel exceeds a pre-set energy detection threshold. If the device finds the operating channel occupied, the equipment may not transmit on that channel during a next, predefined, fixed frame period. However, if the device finds the operating channel (s) to be clear, e.g. the sensed energy level is below the energy detection threshold, the device may transmit on the channel.

LBT failure detections may occur, for example, because of a collision on the channel, detecting the channel to be busy, or because of poor link quality. In general, the LBT failure may be any failure that prevents operation of the LBT transmissions. Upon detecting LBT failure (s) , the terminal device may be configured to report the failure to a serving access node. In some cases, the terminal device may be configured to report a consistent LBT failure. The consistent failure may be detected based on a determined number of LBT failures within a determined time interval. A problem with such an approach is that a burst of transmission failures due to LBT failures may trigger the reporting and, if the reason for the failures is very temporary, the reporting may be unnecessary. For example, when the terminal device has many pending transmissions in a short period of time and the channel is busy, a high number of LBT failure indications may be detected in a rapid succession, leading early declaration of a consistent LBT failure event even though after such a burst of LBT failures, the channel would be free to use.

Figure 2 illustrates a process for detecting communication failures in a wireless device, e.g. the

terminal device

100 or 102. Referring to Figure 2, the process comprises as performed by the terminal device: detecting (block 200) a first communication failure indication and, as a response to said detecting, incrementing a failure counter and starting a failure count timer; while the failure count timer is running, if a new communication failure indication is detected (block 202) , omitting (block 208) incrementing the failure counter; after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected (block 202) , incrementing (block 206) the failure counter; in response to the failure counter reaching a determined count value, triggering (block 212) reporting of a communication failure; and receiving (block 214) , in response to reporting the communication failure, a message comprising an operating parameter.

The embodiment of Figure 2 provides the failure count timer to bundle a number of successive communication failure indications together into a single incrementation of the failure counter. In other words, the failure count timer provides a guard time for incrementing the failure counter. Accordingly, a sudden burst of communication failure indications does not trigger the reporting of the consistent communication failure. This results in reduction in unnecessary reports and/or false alarms.

Below, some embodiments of the process of Figure 2 are described in the context of listen-before-talk (LBT) failure indications. However, embodiments of the invention are applicable to other communication failures as well, e.g. beam failure detections. The beam failure detection may refer to a situation where a beam directed to the terminal device by using beamforming techniques is suffering from failures, e.g. due to sub-optimal directivity of the beam and/or channel conditions. The principles of Figure 2 are equally applicable to detection of other communication failures using timers for detecting a consistent communication failure.

In an embodiment of Figure 2, the first failure indication refers to a failure indication detected when the failure counter is at its initial value, e.g. zero.

Still referring to Figure 2, upon detecting the new communication failure indication in block 202, the terminal device may check in block 204 whether or not the failure count timer is still running. If the failure count timer is running, the process proceeds to block 208 and, thereafter, returns to block 202 upon detecting a new communication failure indication. If the failure count timer is detected as not running in block 204, the process proceeds to block 206. Thereafter, the process proceeds to block 210 to determine whether or not the failure counter has reached a value that triggers the communication failure reporting (block 212) . The value may be a threshold value. The value may be preconfigured or received in a measurement request or in another message. The value may be configured by the network device for the UE, e.g., through radio resource control (RRC) signalling. If the value has been reached, the process proceeds from block 210 to 212. Otherwise, the process returns to block 202 upon detecting a new communication failure indication.

In an embodiment, the communication failure is reported to the serving access node via RRC signalling or via MAC control element. In response to the reported communication failure, the access node may adjust operating parameters of the terminal device, such as trigger change of carrier frequency, bandwidth part (BWP) , or the channel the terminal device communicates with the access node. The serving access node may then generate and transmit the new operating parameter (s) to the terminal device in the message received in block 214.

In an embodiment, the LBT failure indication is based on a failure in uplink transmission of at least one of the following uplink messages: an acknowledgment/negative acknowledgment message, a channel state indication report, a scheduling request, a random access message, payload data, a physical uplink shared channel (PUSCH) transmission, a physical uplink control channel (PUCCH) transmission, and configured grant (CG) transmission.

In an embodiment, the LBT failure occurs when transmitting an uplink message according to the LBT procedure, e.g. any one of the LBT procedures described above, where the terminal device performs channel access only upon detecting, in a clear-channel assessment, a channel to have been idle for a determined time interval.

Figure 3 illustrates an embodiment of the process of Figure 2. The same reference numbers refer to the same or substantially similar operations as in Figure 2. In the embodiment of Figure 3, the failure count timer is started or restarted as a response to detecting the new listen-before-talk failure indication after the expiry of the failure count timer (block 300) . In other words, when the failure counter is incremented in block 206 as a response to the failure count timer having expired, and the failure counter is not high enough to trigger the reporting in

blocks

210 and 212, the failure count timer may be started or restarted in block 300 to prevent a potential subsequent burst of LBT failure indications from incrementing the failure counted.

Figure 4A illustrates an embodiment of Figure 3 that is directly applicable to the embodiment of Figure 2 as well, with the removal of block 300. In the embodiment of Figure 4A, a further timer called a failure detection timer is used for counting a number of listen-before-talk failure indications within a determined time interval. The failure detection timer may be used for determining that enough LBT failure indications have been detected to trigger the reporting. Referring to Figure 4A, the device may start the failure detection timer in block 400 as a response to above-mentioned detecting the first LBT failure indication (see block 200) . As a consequence, block 400 is the modification of block 200 in the sense that the failure detection timer is also started, in addition to incrementing the failure counter and starting the failure count timer.

Further referring to Figure 4A, the reporting of the LBT failure (block 212) may be triggered, if or only if the failure counter reaches the determined count value while the failure detection timer is running (block 402) . In other words, after incrementing the failure counter in block 206, it may be checked in block 402 whether the failure counter has reached the value that triggers block 212 while the failure detection (FD) timer is running. If the value is reached while the failure detection timer is running, block 212 may be triggered. If not, the process may return to block 202 (optionally through block 300) .

In an embodiment, the failure detection timer is started or restarted at the same time as the failure count timer is started or restarted. In an embodiment, the restart of the failure detection timer is triggered only when the failure count timer is not running.

In an embodiment, the failure detection timer is restarted after each detection of LBT failure indication. In this embodiment, the status of the failure count timer is not a criterion for restarting the failure detection timer, e.g. the status of the failure count timer may be ‘running’ or ‘stopped’ .

An alternative procedure may replace block 402 with the above-described block 210 and, additionally, a separate procedure for operating the failure detection timer may be executed. Figure 4B illustrates that separate procedure. Referring to Figure 4B, the failure detection timer may be started in block 400, as described above. If block 212 is triggered, the failure detection timer may be stopped, unset, or reset (block 416) . The failure count timer and the failure counter may also be reset in block 416. The failure detection timer may be restarted (block 410) at the same time as the failure count timer is restarted in block 300. Alternatively, the failure detection timer may be restarted when the failure count timer is incremented (block 206) . Yet alternatively, the failure detection timer may be restarted when the new LBT failure indication is detected (block 202) .

When the failure detection timer expires in block 412, the failure counter may be reset and/or set to its initial value (which may be zero ‘0’ ) in block 414, thus ending the process such that the next LBT failure indication is considered as the first LBT failure indication (block 200, 400) .

In an embodiment, the operation of the above-described timers and the failure counter may be defined in a language of 3GPP (3 ^rd Generation Partnership Project) specifications as follows:

The MAC entity shall:

1> if LBT failure instance indication has been received from lower layers and LBTCountTimer is not running:

2> start or restart the LBTCountTimer;

2> start or restart the LBTFailureDetectionTimer;

2> increment LBT_COUNTER by 1;

2> if LBT_COUNTER >= LBTFailureInstanceMaxCount:

3>declare consistent LBT failure.

1> if the LBTFailureDetectionTimer expires;

2> stop the LBTCountTimer;

2> set LBT_COUNTER to 0.

The LBT failure instance indication may correspond to the above-described LBT failure indication, LBTCountTimer may correspond to the failure count timer, LBTFailureDetectionTimer may correspond to the failure detection timer, and LBT_COUNTER may correspond to the failure counter. MAC refers to Medium Access Control, and the lower layers may refer to the physical layer (PHY) . In other words, the operation is described from the perspective of the MAC layer. In some cases, failure count timer could be referred to as failure prohibit timer or LBT failure prohibit timer.

Figures 5 and 6 illustrate the operation of the embodiments in a case where there is a short, temporary burst of LBT failures (Figure 5) and in a case of a truly consistent LBT failure (Figure 6) . In Figures 5 and 6, the operation of the device on the MAC layer and on the physical layer is illustrated. The vertical lines on the time line illustrate uplink transmission opportunities where the physical layer attempts uplink transmission, e.g. by scanning the channel in the CCA procedure and/or by performing channel access. A tick in connection with a transmission opportunity indicates successful uplink LBT transmission while a cross represents a LBT failure indication, e.g. failed transmission or busy channel.

Referring to Figure 5, the first transmission opportunity is successfully utilized. At the second transmission opportunity, the physical layer fails the transmission and, as a consequence, may indicate the LBT failure to the MAC layer. The failure may be the detection of the channel to be busy and incapability of accessing the channel to perform the LBT uplink transmission. Other communication failures may be equally possible, as described above. Upon detecting the LBT failure indication, the MAC layer may increment the failure counter (by one) and start the failure detection timer and the failure count timer. The next three transmission opportunities also fail while the failure count timer is running and, therefore, the MAC layer will not increment the failure counter. Upon expiry of the failure counter, the subsequent failure indication (the right-most cross) causes incrementation of the failure counter and, additionally restart of the failure count timer that had expired.

Additionally, detection of the new LBT failure indication while the failure count timer is not running may trigger restart of the failure detection timer, in addition to the restart of the failure count timer (as illustrated in Figure 5) . In an alternative embodiment, the failure detection timer is restarted upon detecting any or every new listen-before-talk failure indication, e.g. any one of the failure detection indications detected while the failure count timer is running. In both embodiments, the detection of a new LBT failure indication may thus prolong the time interval counted with the failure detection timer. As a consequence, the operation of the failure detection timer may be understood as a type of a sliding window. In yet another embodiment, the failure detection timer is kept running from when it is started until it expires. In other words, it is not restarted or stopped while it is running. After its expiry, detection of a new LBT failure then starts or restarts the failure detection timer again.

In the embodiments of the previous paragraph, and in all embodiments described above, the restarting of a timer may be understood as resetting the timer to start to count from its respective initial value. In other words, the restarting includes resetting the timer and starting the timer to run.

After the LBT failure indication that caused the restart of the timers, the subsequent uplink transmissions are successful and, as a consequence, the failure detection timer expires without triggering the transmission of the report indicating consistent LBT failures. No matter how many LBT failures occur while the failure count timer is running, the LBT failures are counted as one. Therefore, a rapid burst of LBT failures has a reduced effect with respect to incrementing the failure counter.

Referring to Figure 6, the difference is that the LBT failures continue after the first burst of LBT failures. As a consequence, after the first restart of the timers (see middle arrows representing the timers in Figure 6) , the next uplink transmission may be successful (the rightmost tick in Figure 6) . The successful LBT transmission may not cause any action to the timers or the failure counter. The failure count timer expires thereafter. Therefore, the next LBT failure again causes the restarts of the failure count timer and the failure detection timer. The failure count timer then expires without any further LBT failures. The next LBT failure (the rightmost cross in Figure 6) may be the one that brings the failure counter to the value that triggers the reporting. The failure detection timer is still running so block 212 may be triggered and the consistent LBT failure may be reported to the serving access node 104. The failure detection timer may also be stopped upon triggering block 212. In the illustration of Figure 6, the failure detection timer runs beyond the detection of the failure triggering block 212 to illustrate that block 212 is triggered while the failure detection timer is running.

In an embodiment, the failure count timer and/or failure detection timer is configured to count a determined number of time units, e.g. seconds, milliseconds, or microseconds. Some examples of the time intervals counted by the failure detection timer are 20, 30, 40, 80, and 120ms. Some examples of the time intervals counted by the failure count timer are 2, 5, 8, and 10 ms.

In an embodiment, the failure count timer and/or failure detection timer is configured to count a determined number of uplink time resources, e.g. slots or sub-frames.

In an embodiment, the failure count timer is configured to count a determined portion of the duration counted by the failure detection timer. For example, the failure count timer may be configured to count a time half of the time counted by the failure detection timer. In other words, if the failure detection timer is set to count 20 ms, the failure count timer is set to count 10 ms. In another embodiment, another ratio or division is used, e.g. 1/3 or 1/4. The time counted by the failure count timer may always be shorter than the time counted by the failure detection timer.

In an embodiment, detection of a successful transmission while the failure detection timer and/or the failure count timer is/are running causes resetting of one or both of the timers and/or the failure counter. Figure 7 illustrates such an embodiment. The process of Figure 7 may be entered from one of the

blocks

200, 202, and 210, for example. For example, a number of (at least one) successful LBT transmissions may stop the failure count timer from running, and a subsequent detection of an LBT failure indication may again increase the failure counter and start or restart the failure count timer. This is illustrated in Figure 7 by determining, in block 702 upon detecting a successful LBT transmission in block 700 while the failure counter is running, whether or nor not to perform resetting at least one of the failure counter, failure count timer, and failure detection timer. A separate determination on the basis of the same criterion or different criteria may be made for each of the failure counter, failure count timer, and failure detection timer. Upon determining to perform resetting, block 704 is executed where the timer (s) and/or the failure counter is reset. Thereafter, the process may end, thus ending the process of Figure 2 or any one of its embodiments as well. Upon determining not to reset the counter and/or the timer (s) , the process may return to block 202 for detection of a subsequent LBT failure indication or to block 700 for detection of another successful LBT transmission.

In some examples, a number of (at least one) successful LBT transmissions may be used as the criterion for stopping the failure count timer and/or failure detection timer from running as well as for resetting the failure counter. The number of successful LBT transmissions may be evaluated on the basis of successful LBT transmissions detected while the failure count timer and/or failure detection timer is running and, if the number of successful LBT transmissions detected while the timer (s) is/are running exceed a determined threshold, the timers may be stopped (and reset) and the failure counter may be reset to its initial value, e.g. zero. The number of successful LBT transmissions may or may not be successive, i.e. the process may take into account all the successful LBT transmissions detected while the timer (s) is/are running or only successive successful LBT transmissions. . In the latter case, one or more LBT failure indications may occur between successful transmissions without resetting the counting of successful LBT transmissions. Yet in another embodiment, a LBT failure indication detected after a successful LBT transmission decrements a counter counting the number of successful LBT transmissions. In a similar embodiment, a successful LBT transmission decrements the failure counter.

Figure 8 illustrates an embodiment of a structure of the above-mentioned functionalities of an apparatus executing the functions of the

terminal device

100, 102 in the embodiments described above. The apparatus may be a terminal device or a client device of a wireless network, e.g. an LTE or 5G based cellular communication network. In other embodiments, the apparatus may be a circuitry or an electronic device realizing some embodiments of the invention in the terminal device. The apparatus may be or may be comprised in a computer (PC) , a laptop, a tablet computer, a cellular phone, a palm computer, a sensor device, or any other apparatus provided with radio communication capability. In another embodiment, the apparatus carrying out the above-described functionalities is comprised in such a device, e.g. the apparatus may comprise a circuitry such as a chip, a chipset, a processor, a micro controller, or a combination of such circuitries in any one of the above-described devices. The apparatus may be an electronic device comprising electronic circuitries for realizing some embodiments of the present invention.

Referring to Figure 8, the apparatus may comprise a processing circuitry 50 comprising a communication circuitry 56 providing the apparatus with capability of communicating in the wireless network of the access node 104. The communication circuitry 56 may employ a radio interface 52 providing the apparatus with radio communication capability. The radio interface 52 may support uplink frame transmissions on the unlicensed frequency bands. It may comprise radio frequency converters and components such as an amplifier, filter, frequency-converter, (de) modulator, and encoder/decoder circuitries and one or more antennas. The communication circuitry may comprise a radio modem configured to carry out transmission and reception of messages in the wireless network. The radio modem may implement at least a physical layer 57 and a MAC layer 55 for the LBT communications.

The processing circuitry 50 may further comprise a timer management circuitry 58 configured to communicate with the MAC layer 55 and to operate the failure count timer and the failure detection timer, as described above. Upon detecting the first LBT failure indication or a new LBT failure indication while the failure count timer is not running, the timer management circuitry may (re) start the failure detection timer and the failure count timer, as described above. In its simplest form, the timer management circuitry may consist of the timers. When detecting new LBT failure indications, the MAC layer may communicate with the timer (s) in order to detect whether or not the consistent LBT failure reporting is triggered.

The apparatus may further comprise an application processor 56 executing one or more computer program applications that generate a need to transmit and/or receive data through the communication circuitry 56. The application processor may form an application layer of the apparatus. The application processor may execute computer programs forming the primary function of the apparatus. For example, if the apparatus is a sensor device, the application processor may execute one or more signal processing applications processing measurement data acquired from one or more sensor heads. If the apparatus is a computer system of a vehicle, the application processor may execute a media application and/or an autonomous driving and navigation application. The application processor may generate data to be transmitted in the wireless network.

The processing circuitry 50 may comprise at least one processor. The apparatus may further comprise a memory 60 storing one or more computer program products 62 configuring the operation of said processor (s) of the apparatus. The memory 60 may further store a configuration database 64 storing operational configurations of the apparatus. The configuration database 64 may, for example, store the LBT parameters, the time intervals counted by the timers, and the threshold value for triggering the consistent LBT failure reporting.

As used in this application, the term ‘circuitry’ refers to one or more of the following: (a) hardware-only circuit implementations such as implementations in only analog and/or digital circuitry; (b) combinations of circuits and software and/or firmware, such as (as applicable) : (i) a combination of processor (s) or processor cores; or (ii) portions of processor (s) /software including digital signal processor (s) , software, and at least one memory that work together to cause an apparatus to perform specific functions; and (c) circuits, such as a microprocessor (s) or a portion of a microprocessor (s) , that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of ‘circuitry’ applies to uses of this term in this application. As a further example, as used in this application, the term “circuitry” would also cover an implementation of merely a processor (or multiple processors) or portion of a processor, e.g. one core of a multi-core processor, and its (or their) accompanying software and/or firmware. The term “circuitry” would also cover, for example and if applicable to the particular element, a baseband integrated circuit, an application-specific integrated circuit (ASIC) , and/or a field-programmable grid array (FPGA) circuit for the apparatus according to an embodiment of the invention.

The processes or methods described in Figures 2 to 7 may also be carried out in the form of one or more computer processes defined by one or more computer programs. A separate computer program may be provided in one or more apparatuses that execute functions of the processes described in connection with the Figures. The computer program (s) may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include transitory and/or non-transitory computer media, e.g. a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package. Depending on the processing power needed, the computer program may be executed in a single electronic digital processing unit or it may be distributed amongst a number of processing units.

Embodiments described herein are applicable to wireless networks defined above but also to other wireless networks. The protocols used, the specifications of the wireless networks and their network elements develop rapidly. Such development may require extra changes to the described embodiments. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

An apparatus comprising means for performing:

detecting a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer;

while the failure count timer is running, if a new communication failure indication is detected, omitting incrementing the failure counter;

after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected, incrementing the failure counter;

in response to the failure counter reaching a determined count value, triggering reporting of communication failure; and

in response to reporting the communication failure, receiving a message comprising an operating parameter.
The apparatus of claim 1, wherein the means are configured to start or restart the failure count timer as a response to detecting the new communication failure indication after the expiry of the failure count timer.
The apparatus of claim 1 or 2, wherein the means are configured to start, as a response to said detecting the first communication failure indication, a failure detection timer for counting a number of communication failure indications within a determined time interval.
The apparatus of claim 3, wherein the means are configured to trigger the reporting of the communication failure, if the failure counter reaches the determined count value while the failure detection timer is running.
The apparatus of claim 3 or 4, wherein the means are configured to reset the failure counter in response to expiry of the failure detection timer.
The apparatus of any preceding claim 3 to 5, wherein the means are configured to restart the failure detection timer upon detecting a new communication failure indication while the failure count timer is not running.
The apparatus of any preceding claim 3 to 5, wherein the means are configured to restart the failure detection timer upon detecting any new communication failure indication.
The apparatus of any preceding claim, wherein any one of the communication failure indications is based on a failure in uplink transmission of at least one of the following uplink messages: an acknowledgment/negative acknowledgment message, a channel state indication report, a scheduling request, a random access message, payload data, a physical uplink shared channel transmission, a physical uplink control channel transmission, and a configured grant transmission.
The apparatus of any preceding claim, wherein the communication failure indication is a failure in transmitting an uplink message according to a listen-before-talk procedure where the apparatus performs channel access only upon detecting, in a clear-channel assessment, a channel to have been idle for a determined time interval.
The apparatus of any preceding claim 1 to 8, wherein the communication failure indication is a failure in a radio beam directed by using beamforming techniques.
The apparatus of any preceding claim 1 to 10, wherein the means comprises:

at least one processor; and

at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.
A method comprising:

detecting, by a wireless device, a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer;

while the failure count timer is running, if a new communication failure indication is detected by the wireless device, omitting incrementing the failure counter;

after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected by the wireless device, incrementing the failure counter;

in response to the failure counter reaching a determined count value, triggering by the wireless device reporting of communication failure; and

in response to reporting the communication failure, receiving by the wireless device a message comprising an operating parameter.
The method of claim 12, wherein the wireless device starts or restarts failure count timer as a response to detecting the new communication failure indication after the expiry of the failure count timer.
The method of claim 12 or 13, wherein the wireless device starts, as a response to said detecting the first communication failure indication, a failure detection timer for counting a number of communication failure indications within a determined time interval.
The method of claim 14, wherein the wireless device triggers the reporting of the communication failure, if the failure counter reaches the determined count value while the failure detection timer is running.
The method of claim 14 or 15, wherein the wireless device resets the failure counter in response to expiry of the failure detection timer.
The method of any preceding claim 14 to 16, wherein the wireless device restarts the failure detection timer upon detecting a new communication failure indication while the failure count timer is not running.
The method of any preceding claim 14 to 16, wherein the wireless device restarts the failure detection timer upon detecting any new communication failure indication.
The method of any preceding claim 12 to 18, wherein any one of the communication failure indications is based on a failure in uplink transmission of at least one of the following uplink messages: an acknowledgment/negative acknowledgment message, a channel state indication report, a scheduling request, a random access message, payload data, a physical uplink shared channel transmission, a physical uplink control channel transmission, and a configured grant transmission.
The method of any preceding claim 12 to 19, wherein the communication failure indication is a failure in transmitting an uplink message according to a listen-before-talk procedure where the wireless device performs channel access only upon detecting, in a clear-channel assessment, a channel to have been idle for a determined time interval.
The method of any preceding claim 12 to 19, wherein the communication failure indication is a failure in a radio beam directed by using beamforming techniques.
A computer program product embodied on a computer-readable medium and comprising a computer program code readable by a computer, wherein the computer program code configures the computer to carry out a computer process comprising:

detecting a first communication failure indication in uplink transmission and, as a response to said detecting, incrementing a failure counter and starting a failure count timer;

while the failure count timer is running, if a new communication failure indication is detected, omitting incrementing the failure counter;

after expiry of the failure count timer and while the failure count timer is not running, if a new communication failure indication is detected, incrementing the failure counter;

in response to the failure counter reaching a determined count value, triggering reporting of communication failure; and

in response to reporting the communication failure, receiving a message comprising an operating parameter.