WO2020224772A1

WO2020224772A1 - Selecting an operating channel

Info

Publication number: WO2020224772A1
Application number: PCT/EP2019/061781
Authority: WO
Inventors: Knud Knudsen; Frank Frederiksen; Benny Vejlgaard
Original assignee: Nokia Technologies Oy
Priority date: 2019-05-08
Filing date: 2019-05-08
Publication date: 2020-11-12

Abstract

An apparatus, method and computer program product for: transmitting data on a first operating channel during a first transmission opportunity, determining a set of second operating channels as candidates for transmitting data during a second transmission opportunity, performing, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity and selecting, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

Description

SELECTING AN OPERATING CHANNEL

TECHNICAL FIELD

The present application relates generally to selecting an operating chan nel. More specifically, the present application relates to selecting an operating chan nel for transmitting data.

BACKGROUND

Wireless networks are designed to support a wide range of spectrum bands. The spectrum can be categorised into a licensed spectrum and an unlicensed spectrum. The licensed spectrum is assigned exclusively to operators for independent usage while the unlicensed spectrum is assigned to every user for non-exclusive us age.

SUMMARY

Various aspects of examples of the invention are set out in the claims.

According to a first aspect of the invention, there is provided an appa ratus comprising means for performing: transmitting data on a first operating chan nel during a first transmission opportunity, determining a set of second operating channels as candidates for transmitting data during a second transmission opportuni ty, performing, concurrently with the first transmission opportunity, channel availa bility monitoring on the set of second operating channels such that the channel avail ability monitoring is scheduled to be completed before the second transmission op portunity and selecting, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

According to a second aspect of the invention, there is provided a method comprising: transmitting data on a first operating channel during a first transmission opportunity, determining a set of second operating channels as candi dates for transmitting data during a second transmission opportunity, performing, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity and select ing, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

According to a third aspect of the invention, there is provided a com puter program comprising instructions for causing an apparatus to perform at least the following: transmitting data on a first operating channel during a first transmis sion opportunity, determining a set of second operating channels as candidates for transmitting data during a second transmission opportunity, performing, concurrent ly with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is sched uled to be completed before the second transmission opportunity and selecting, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

According to a fourth aspect of the invention, there is provided an ap paratus comprising at least one processor and at least one memory including com puter program code, the at least one memory and the computer program code config ured to with the at least one processor, cause the apparatus at least to perform: transmit data on a first operating channel during a first transmission opportunity, determine a set of second operating channels as candidates for transmitting data dur ing a second transmission opportunity, perform, concurrently with the first transmis sion opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity, and select, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

According to a fifth aspect of the invention, there is provided a non- transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: transmitting data on a first operating channel during a first transmission opportunity, determining a set of second operat ing channels as candidates for transmitting data during a second transmission oppor tunity, performing, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity and selecting, in response to receiving an indication that at least one sec ond operating channel is available during the channel availability monitoring, a sec ond operating channel for transmitting data.

According to a sixth aspect of the invention, there is provided a com puter readable medium comprising program instructions for causing an apparatus to perform at least the following: transmitting data on a first operating channel during a first transmission opportunity, determining a set of second operating channels as candidates for transmitting data during a second transmission opportunity, perform ing, concurrently with the first transmission opportunity, channel availability moni toring on the set of second operating channels such that the channel availability mon- itoring is scheduled to be completed before the second transmission opportunity, and selecting, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of example embodiments of the pre sent invention, reference is now made to the following descriptions taken in connec tion with the accompanying drawings in which:

Figure 1 shows a part of an exemplifying radio access network in which examples of disclosed embodiments may be applied;

Figure 2 shows a block diagram of an example apparatus in which exam ples of the disclosed embodiments may be applied;

Figure 3 illustrates performing channel availability monitoring on a set of operating channels;

Figure 4 illustrates an example method incorporating aspects of the exam ples of the invention;

Figure 5 shows another example method incorporating aspects of the ex amples of the invention;

Figure 6 illustrates an example signalling diagram incorporating aspects of the examples of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The following embodiments are exemplifying. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of differ ent embodiments may also be combined to provide other embodiments.

Example embodiments relate to selecting an operating channel for trans mitting data such that continuous communication may be provided and communica tion latency is decreased. According to an example embodiment, an apparatus is con figured to transmit data on a first operating channel during a first transmission op portunity. The apparatus may be, for example, a base station such as an eNodeB or gNodeB. The apparatus is further configured to determine a set of second operating channels as candidates for transmitting data during a second transmission opportuni ty and perform channel availability monitoring concurrently with the first transmis sion opportunity. The channel availability monitoring is scheduled to be completed before the second transmission opportunity. The apparatus is further configured to select, in response to receiving an indication that at least one second operating chan nel is available during the channel availability monitoring, a second operating channel for transmitting data. The second operating channel may be selected before or upon expiry of the first transmission opportunity. According to an example embodiment, channel availability monitoring and transmitting/receiving may be performed by a single radio modem.

In the following, different exemplifying embodiments will be described us ing, as an example of an access architecture to which the embodiments may be ap plied, a radio access architecture based on long term evolution advanced (LTE Ad vanced, LTE-A) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodi ments may also be applied to other kinds of communications networks having suita ble means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications sys tem (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 in teroperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, 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 connec tions; 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 struc tures 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 communica tion systems provided with necessary properties.

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

Figure 1 shows 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. 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 an other 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 an other. The (e/g)NodeB is a computing device configured to control the radio re sources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point, an access node, or any other type of interfacing de vice including a relay station 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 is 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 pack ets), 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 inter face 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 in cludes wireless mobile communication devices operating with or without a subscrib er identification module (SIM), including, but not limited to, the following types of devices: 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 multime dia 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 (loT) 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 config ured 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.

A wireless device is a generic term that encompasses both the access node and the terminal device.

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 1CT devices (sensors, actuators, processors microcontrol lers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcat egory 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 enti ties, different units, processors and/or memory units (not all shown in Figure 1) may be implemented.

5G enables using multiple input - multiple output (M1MO) 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 availa ble. 5G mobile communications supports a wide range of use cases and related appli cations 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 integradable 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 in- ter-Rl 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 mo bility.

The current architecture in LTE networks is fully distributed in the radio and 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, tab lets 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 prox imity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mo bile 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 re trieval, autonomic self-healing networks, remote cloud services, augmented and vir tual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time ana lytics, time-critical control, healthcare applications).

The communication system is also able to communicate with other net works, such as a public switched telephone network or the Internet 112, or utilise 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 com munications. 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 com prise 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 lay er 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 in cluding several kinds of cells. Typically, in multilayer networks, one access node pro vides 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 intro duced. Typically, a network which is able to use "plug-and-play" (e/g)Node Bs, in cludes, 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 in stalled within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

As commonly known in connection with wireless communication systems, control or management information is transferred over a radio interface, e.g. between the terminal device 100 and the access node 104.

5G New Radio (NR) networks are designed to support a wide range of fre quency spectrum bands. The spectrum can be categorised into a licensed spectrum and an unlicensed spectrum. The licensed spectrum is assigned exclusively to opera tors for independent usage while the unlicensed spectrum is assigned to every user for non-exclusive usage. In other words, operating on an unlicensed spectrum is sub ject to interference of other users on a shared frequency band. Over the past years, licensed technologies have been migrating to unli censed frequency bands. For example, Licensed Assisted Access (LAA) uses the unli censed 5,2 GHz band to provide additional downlink resources. Another example is enhanced Licensed Assisted Access (eLAA) that is similar to LAA, but also provides additional uplink transmissions.

Due to interference issues on the unlicensed spectrum, channel access for an unlicensed spectrum operation typically uses different co-existence methods to enable co-existence with other devices on the same frequency band. An example of a co-existence method is, for example, a Listen-Before-Talk (LBT) protocol for sharing the unlicensed spectrum with other devices. The LBT protocol specifies that a device does not transmit on a channel that is occupied by some other device. Another exam ple of avoiding interference is frequency hopping. Frequency hopping enables finding unused channels and not using channels that are in heavy use.

Clear channel Assessment (CCA) is a mechanism for determining whether an operating channel is available for transmitting data. The CCA utilizes energy detec tion (ED) to determine presence of signals on a channel. An operating channel shall be considered occupied, if the energy level on the operating channel exceeds a prede termined threshold value.

Typically, CCA is performed after each transmission opportunity (Tx), which introduces challenges in terms of latency. Performing CCA causes interruptions to communication and thereby increases communication latency. This may make it difficult to comply with, for example, low-latency requirements of networks. Further, an interruption to perform CCA introduces a risk that the operating channel may be lost to another node. Latency may also increase, if, based on CCA, it is determined that an operating channel is occupied and the CCA procedure is performed to regain the operating channel.

The example of Figure 2 shows an exemplifying apparatus.

Figure 2 is a block diagram depicting the apparatus 200 operating in ac cordance with an example embodiment of the invention. The apparatus 200 may be, for example, an electronic device such as a chip, chip-set or an access node such as a base station. In the example of Figure 2, the apparatus 200 is a base station such as an eNodeB or gNodeB configured to communicate with a user equipment (UE) 100. The apparatus 200 includes a processor 210 and a memory 260. In other examples, the apparatus 200 may comprise multiple processors.

In the example of Figure 2, the processor 210 is a control unit operatively connected to read from and write to the memory 260. The processor 210 may also be configured to receive control signals received via an input interface and/or the pro cessor 210 may be configured to output control signals via an output interface. In an example embodiment the processor 210 may be configured to convert the received control signals into appropriate commands for controlling functionalities of the appa ratus.

The memory 260 stores computer program instructions 220 which when loaded into the processor 210 control the operation of the apparatus 200 as explained below. In other examples, the apparatus 200 may comprise more than one memory 260 or different kinds of storage devices.

Computer program instructions 220 for enabling implementations of ex ample embodiments of the invention or a part of such computer program instructions may be loaded onto the apparatus 200 by the manufacturer of the apparatus 200, by a user of the apparatus 200, or by the apparatus 200 itself based on a download pro gram, or the instructions can be pushed to the apparatus 200 by an external device. The computer program instructions may arrive at the apparatus 200 via an electro magnetic carrier signal or be copied from a physical entity such as a computer pro gram product, a memory device or a record medium such as a Compact Disc (CD), a Compact Disc Read-Only Memory (CD-ROM), a Digital Versatile Disk (DVD) or a Blu- ray disk.

According to an example embodiment, the apparatus 200 is configured to transmit data on a first operating channel during a first transmission opportunity. Data is transmitted using radio frames having a particular frame structure. A frame structure may comprise a structure that is designed for Frequency Division Duplex (FDD) or a frame structure that is designed for Time Division Duplex (TDD). In FDD a first operating channel is provided for downlink transmission and a second operating channel is provided for uplink transmission. In other words, different spectrum fre quencies may be used at the same time. In TDD both uplink transmission and down link transmission use the same frequency spectrum, but at different times. Typically, a radio frame is of 10 ms duration and a frame is further divided into subframes. A sub- frame is further divided into slots.

A transmission opportunity comprises a time interval for transmitting or initiating transmitting data. An apparatus may transmit multiple radio frames con secutively during the time interval.

According to an example embodiment, the apparatus 200 is further con figured to determine a set of second operating channels as candidates for transmit ting data during a second transmission opportunity. The set of second operating channels may comprise one or more second operating channels. A second channel may comprise a channel that is a neighbouring channel to the first operating channel. A neighbouring channel to the first channel may comprise a channel that is comprised by the same frequency band as the first channel. For example, a neighbouring channel may be an operating channel above or below the first operating channel separated by a distance between the channels. According to an example embodiment, the apparatus 200 is configured to inform a responding device to about the set of second operating channels. In other words, the responding device is informed about the channels to listen to. A respond ing device may be, for example, a user equipment (UE) 100. If the set of channels is changed, the apparatus 200 is configured to provide information on the updated set using, for example, Radio Resource Control (RRC) protocol such as cell common sig nalling (RRC broadcast) or through UE signalling (RRC dedicated). Figure 6 illustrates a signalling diagram of informing a receiving device about the set of second operating channels using RRC protocol.

According to an example embodiment, the first operating channel and the second operating channel are provided on an unlicensed spectrum. As mentioned above, unlicensed spectrum is assigned to every user for non-exclusive usage. An un licensed spectrum may comprise different frequency bands, for example, 2,4 GHz, 5,8 GHz or 60 GHz frequency band. An unlicensed spectrum may also comprise different frequency ranges such as 5-7 GHz or 57-71 GHz. Unlicensed spectrum may comprise different frequency bands in different geographical areas such as Europe and the USA.

According to an example embodiment, the unlicensed spectrum comprises a frequency band allocated for time division duplex (TDD) operation. In TDD both uplink transmission and downlink transmission use the same frequency spectrum, but at different times. For example, the frequency band may comprise band 46 cover ing a 775 MHz frequency range from 5,150 GHz to 5,925 GHz.

According to an example embodiment, the apparatus 200 is configured to perform, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity.

Channel availability monitoring may comprise monitoring an operating channel to determine whether the operating channel is available for transmitting data on the operating channel. Alternatively or additionally, channel availability monitor ing may comprise determining whether radio energy level on an operating channel is above a threshold value. According to an example embodiment, channel availability monitoring is performed prior to transmitting data on an operating channel. Channel availability monitoring may be performed concurrently on multiple second operating channels. Channel availability monitoring may also be performed continuously or dis- continuously, for example, at set time intervals.

Initiating channel availability monitoring may be dependent upon one or more criteria. The one or more criteria may relate to ongoing transmission, ongoing transmission opportunity or an upcoming transmission opportunity. For example, initiating channel availability monitoring may depend upon a duration of the remain ing ongoing transmission opportunity. According to an example embodiment, the ap- paratus 200 is configured to start channel availability monitoring, in response to re ceiving information, that the remaining duration of the ongoing transmission oppor tunity is below a predetermined threshold value.

Without limiting the scope of the claims, an advantage of performing channel availability monitoring on a set of second operating channels is that the like lihood of finding an available operating channel is increased.

Scheduling the channel availability monitoring to be completed before the second transmission opportunity may comprise determining a start time for perform ing channel availability monitoring. The start time may depend upon the duration of channel availability monitoring on an operating channel. The duration of channel availability monitoring may be shorter than the duration of the first transmission op portunity or the duration of channel availability monitoring may be equal to the dura tion of the first transmission opportunity. In other words, channel availability moni toring may be performed concurrently with transmitting and/or receiving data.

According to an example embodiment, the apparatus 200 is configured to determine the duration of channel availability monitoring on a second operating channel. The duration of channel availability monitoring may be different on different operating channels.

According to an example embodiment, the apparatus 200 is configured to determine the duration of channel availability monitoring based on a defer period and a multiplied slot duration.

A defer period comprises a minimum period of time for monitoring an op erating channel. In other words, a deferring period refers to a period time a transmis sion needs to be deferred before initiating the transmission. If an operating channel is determined to be unavailable, the transmission is deferred further. A defer period may be different for different transmission priority classes. A defer period may be determined based on a default value and a value that depends upon transmission pri ority. The default value may be, for example 16gs and the value that depends upon transmission priority may be, for example, 9gs multiplied by the priority class. For example, if the priority class is 1, the defer period is 16gs+9gs = 25 gs.

A multiplied slot duration comprises a slot duration multiplied by a ran dom number. The random number may be between 0 and a minimum contention window size. A contention window determines a number of available slots that need to be determined before transmitting data. In other words, the contention window works like a timer that is paused whenever an unavailable slot is determined and turned again on when an available slot is determined. In an example embodiment, the minimum contention window size is 3. For example, if the slot duration is 9 gs and the random number is 3, the multiplied slot duration is 27 gs. Hence, the duration of the channel availability monitoring is 52 gs (a defer period of 25 gs + multiplied slot du- ration 27 gs equals 52 gs). On the other hand, if the slot duration is 9 gs and the ran dom number is zero, the multiplied slot duration is 0 gs. Hence, the duration of the channel availability monitoring is 25 gs. In other words, duration of the channel availability monitoring may be between 25 gs and 52 gs.

According to an example embodiment, the apparatus 200 is further con figured to determine the end time of the first transmission opportunity.

According to an example embodiment, the apparatus 200 is configured to determine a start time for performing channel availability monitoring based on the end time of the first transmission opportunity and the duration of channel availability monitoring. For example, the apparatus 200 may determine the start time by sub tracting the duration of channel availability monitoring from the end time of the first transmission opportunity. Channel availability monitoring is initiated during the first transmission opportunity based on the determined start time.

According to an example embodiment, the apparatus 200 is configured to provide different scheduling for different operating channels included in the set of second operating channels. Providing different scheduling for different operating channels may comprise determining different start times for performing channel availability monitoring on different operating channels. For example, the start time for initiating channel availability monitoring may be a first point in time for a first operating channel and a second point in time for a second operating channel, wherein the first point in time occurs at a different time instant than the second point in time. According to an example embodiment, the apparatus 200 is configured to initiate channel availability monitoring based on the determined start time.

According to an example embodiment, the apparatus 200 is configured to determine a channel specific start time for channel availability monitoring on a sec ond operating channel. A channel specific start time may comprise determining a start time for an operating channel independent of determining start times for other operating channels.

Without limiting the scope of the claims, an advantage of scheduling the channel availability monitoring to be completed before the second transmission op portunity is that interruptions in transmission may be reduced.

Performing channel availability monitoring concurrently with the first transmission opportunity may comprise performing channel availability monitoring during the first transmission opportunity. Performing channel availability monitoring concurrently with the first transmission opportunity may be carried out in different ways. Concurrent channel availability monitoring may be based on technical features of the apparatus 200, based on functions of the apparatus 200 or based on finding opportunities to perform channel availability monitoring during operation of the ap paratus 200. Technical features may comprise, for example, one or more supported technologies. Functions of the apparatus may comprise, for example, different fea tures that the apparatus is configured to perform.

According to an example embodiment, the apparatus 200 is configured to support full duplex communication to enable performing channel availability moni toring while transmitting data. An apparatus supporting full duplex communication is configured to transmit and receive data at the same time. In other words, data can be transmitted in both directions on an operating channel at the same time.

According to another example embodiment, the apparatus 200 is config ured to hand the transmission opportunity over to a responding device while per forming the channel availability monitoring.

According to a yet further example embodiment, the apparatus 200 is con figured to perform channel availability monitoring during normal uplink transmis sion. In other words, the apparatus 200 may automatically have an opportunity to perform channel availability monitoring during a receive time interval.

Without limiting the scope of the claims, an advantage of performing channel availability monitoring concurrently with the first transmission opportunity is that an interruption to communication may be avoided.

According to an example embodiment, the channel availability monitoring comprises clear channel assessment. There are different ways to implement clear channel assessment and therefore, clear channel assessment procedures may differ from geographical region to geographical region and/or from technology to technolo gy-

According to an example embodiment, the apparatus 200 is configured to select, in response to receiving an indication that at least one second operating chan nel is available during the channel availability monitoring, a second operating channel for transmitting data.

The apparatus 200 is configured to select an indicated operating channel in response to receiving an indication that a single operating channel is available. The apparatus 200 may be configured to select an available operating channel in different ways in response to receiving an indication that more than one operating channel is available According to an example embodiment, the apparatus 200 is configured to randomly select an available operating channel in response to receiving an indication that more than one channel is available. According to another example embodiment, the apparatus 200 is configured to select an available operating channel having the lowest energy level of the available operating channels in response to receiving an indication that more than one channel is available. According to a further example embodiment, the apparatus 200 is configured to select an available channel that has been selected the lowest number of times within a predefined time period. According to a yet further example embodiment, the apparatus is configured to select an availa- ble channel based on a prioritization scheme in response to receiving an indication that more than one channel is available.

The apparatus 200 may be configured to select the second operating channel upon different phases of the first transmission opportunity. For example, the apparatus 200 may be configured to select the second operating channel in depend ence upon the expiry of the first transmission opportunity.

According to an example embodiment, the apparatus 200 is configured to select the second operating channel before expiry of the first transmission opportuni ty. According to another example embodiment, the apparatus 200 is configured to select the second operating channel upon expiry of the first transmission opportunity.

Selecting a second operating channel before expiry of the first transmis sion opportunity may be performed in alignment with the ongoing transmission. For example, selecting a second operating channel may be performed in dependence up on a radio frame structure.

According to an example embodiment, the apparatus 200 is configured to select the second operating channel upon a slot boundary of an ongoing transmission. According to another example embodiment, the apparatus 200 is configured to select the second operating channel upon a frame boundary of an ongoing transmission.

Without limiting the scope of the claims, an advantage of selecting a sec ond operating channel before expiry of the first transmission period is that a time interval for performing channel availability monitoring between the first transmis sion opportunity and the second transmission opportunity may be avoided, thereby reducing latency.

Similarly to selecting a second operating channel, switching transmission to a selected second operating channel may be performed upon expiry of the first transmission opportunity or before the expiry of the first transmission opportunity. According to an example embodiment, the apparatus 200 is configured to initiate transmission on the second operating channel upon expiry of the first transmission opportunity. According to another example embodiment, the apparatus 200 is config ured to initiate transmission on the second operating channel before expiry of the first transmission opportunity.

According to an example embodiment, the apparatus 200 comprises means for performing the features of the apparatus 200, wherein the means for per forming comprises at least one processor 210, at least one memory 260 including computer program code 220, the at least one memory 260 and the computer program code 220 configured to, with the at least one processor 210, cause the performance of the apparatus 200.

According to an example embodiment, the apparatus 200 is a base station. The base station may be, for example, an eNodeB or gNodeB. Figure 3 illustrates transmitting data during a first transmission period and performing concurrent channel availability monitoring on a set of second operat ing channels. In the example of Figure 3 channel availability monitoring comprises Clear Channel Assessment (CCA). As illustrated in Figure 3, a transmission is ongoing on channel A during a first transmission (Tx) opportunity. Tx DL illustrates a down link transmission and Rx UL illustrates receiving an uplink transmission. In Figure 3, the transmission opportunity is handed over to a responding device during the first transmission opportunity. According to certain regulations, channel availability moni toring is not required if the gap between switching from downlink transmission to receiving an uplink transmission is small enough. For example, ETS1 regulations do not require performing channel availability monitoring if the gap is below 16 gs. Con currently with the first transmission opportunity, channel availability monitoring is performed on a set of neighbouring operating channels such that the start time 301 of channel availability monitoring is different on different operating channels. The start time depends upon the duration of channel availability monitoring on different oper ating channels. A start time may be determined by subtracting channel availability duration from the end time of the first transmission opportunity. A duration may be calculated as explained above. In Figure 3, channel availability monitoring on the il lustrated channels is completed upon expiry 302 of the first transmission opportunity or before the second transmission (Tx) opportunity. In response to receiving an indi cation that channel B is available, channel B is selected, and data is transmitted on channel B during a second transmission opportunity.

Figure 4 illustrates an example method 400 incorporating aspects of the previously disclosed embodiments. More specifically, the example method 400 illus trates selecting a second operating channel.

The method starts with transmitting 405 data on a first operating channel during a first transmission opportunity. The method continues with determining 410 a set of second operating channels as candidates for transmitting data during a sec ond transmission opportunity.

The method further continues with performing 415, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity.

The method still continues with selecting 420, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data. The second operating channel may be selected before or upon expiry of the first transmission opportunity. The second operating channel may be selected upon a slot boundary or a frame boundary of an ongoing transmission. Figure 5 illustrates another example method 500 incorporating aspects of the previously disclose embodiments. More specifically, the example method 500 il lustrates performing channel availability monitoring on a set of second operating channels concurrently with a first transmission opportunity.

First, there is a need for a new transmission opportunity. The method starts with waiting 505 for the remaining duration of the current transmission oppor tunity to be below a threshold value.

The method continues with determining whether the apparatus 200 sup ports 510 full duplex communication. If full duplex is supported, a start time for per forming channel availability monitoring is determined 520. The start time may be determined as explained above. In this example, channel availability monitoring com prises CCA. However, if full duplex is not supported, the transmission opportunity is first handed 515 over to a receiving device.

The start time for CCA is determined 520 for each operating channel in a set of second operating channels. Different channels may have different start times. The start time may be determined based on the end time of the current transmission opportunity and the duration of the CCA on the operating channel. The duration of channel availability monitoring may be determined as explained above.

Based on the determined start times for each operating channel in the set of second operating channels, the CCA is scheduled 525 on each operating channel such that it is completed before a second transmission opportunity.

The method further continues with waiting 530 for the CCA to be complet ed and determining 535 whether an available operating channel was identified in the set of second operating channels. If an available operating channel is identified the channel is selected 540 and the apparatus 200 initiates transmitting data on the channel. However, if an available operating channel is not detected, it is determined 545 whether the CCA is still running. If the CCA is running, the method returns to waiting 530 for the CCA to be completed. On the other hand, if it is determined that the CCA is not running, the method returns to determining 520 a start time for the CCA.

Without limiting the scope of the claims, an advantage of performing channel availability monitoring on a set of second operating channels concurrently with transmitting data on a first operating channel during a first transmission oppor tunity is that communication need not to be interrupted for performing channel availability monitoring. An advantage of performing channel availability monitoring on a set of operating channels is that the likelihood of finding a free channel increases.

Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodi ments disclosed herein is continuous communication with decreased communication latency.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on the apparatus, a separate device or a plurality of devices. If desired, part of the software, application logic and/or hardware may reside on the apparatus, part of the software, application logic and/or hardware may reside on a separate device, and part of the software, ap plication logic and/or hardware may reside on a plurality of devices. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this docu ment, a 'computer-readable medium' may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connec tion with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted in FIGURE 2. A computer- readable medium may comprise a computer-readable storage medium that may be any media or means that can contain or store the instructions for use by or in connec tion with an instruction execution system, apparatus, or device, such as a computer.

If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the in dependent claims, and not solely the combinations explicitly set out in the claims.

It will be obvious to a person skilled in the art that, as the technology ad vances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An apparatus comprising means for performing:

transmitting data on a first operating channel during a first transmis sion opportunity;

determining a set of second operating channels as candidates for transmitting data during a second transmission opportunity;

performing, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity; and

selecting, in response to receiving an indication that at least one sec ond operating channel is available during the channel availability monitoring, a sec ond operating channel for transmitting data.

2. The apparatus according to claim 1, wherein the apparatus comprises means for selecting the second operating channel before expiry or upon expiry of the first transmission opportunity.

3. The apparatus according to claim 2, wherein the apparatus comprises means for selecting the second operating channel upon a slot boundary of an ongoing transmission.

4. The apparatus according to claim 2, wherein the apparatus comprises means for selecting the second operating channel upon a frame boundary of an ongo ing transmission.

5. The apparatus according to any preceding claim, wherein the appa ratus comprises means for initiating transmission on the second operating channel upon expiry of the first transmission opportunity.

6. The apparatus according to any preceding claim, wherein the channel availability monitoring comprises clear channel assessment.

7. The apparatus according to any preceding claim, wherein the appa ratus comprises means for randomly selecting an available operating channel in re sponse to receiving an indication that more than one channel is available.

8. The apparatus according to any preceding claim, wherein the appa- ratus comprises means for supporting full duplex communication to enable perform ing channel availability monitoring while transmitting the data.

9. The apparatus according to any preceding claim, wherein apparatus further comprises means for handing the transmission opportunity over to a re sponding device while performing the channel availability monitoring.

10. The apparatus according to any preceding claim, wherein the appa ratus comprises means for providing different scheduling for different operating channels included in the set of second operating channels.

11. The apparatus according to any preceding claim, wherein apparatus comprises means for informing a responding device about the set of second operating channels.

12. The apparatus according to any preceding claim, wherein the first op erating channel and the second operating channel are provided on an unlicensed spectrum.

13. The apparatus according to claim 12, wherein the unlicensed spec trum comprises a band allocated for time division duplex operation.

14. The apparatus according to any preceding claim, wherein the appa ratus further comprises means for determining a channel specific start time for chan nel availability monitoring on a second operating channel.

15. The apparatus according to any preceding claim, wherein the appa ratus is a base station.

16. The apparatus according to any preceding claim, wherein the means for performing comprises at least one processor, at least one memory including com puter program code, the at least one memory and the computer program code config ured to, with the at least one processor, cause the performance of the apparatus.

17. A method comprising:

determining a set of second operating channels as candidates for transmitting data during a second transmission opportunity; performing, concurrently with the first transmission opportunity, channel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity; and

18. A computer program comprising instructions for causing an apparatus to perform at least the following:

19. An apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the comput er program code configured to with the at least one processor, cause the apparatus at least to perform:

transmit data on a first operating channel during a first transmission opportunity;

determine a set of second operating channels as candidates for trans mitting data during a second transmission opportunity;

perform, concurrently with the first transmission opportunity, chan nel availability monitoring on the set of second operating channels such that the channel availability monitoring is scheduled to be completed before the second transmission opportunity; and

select, in response to receiving an indication that at least one second operating channel is available during the channel availability monitoring, a second operating channel for transmitting data.

20. The apparatus according to claim 19, wherein the apparatus is configured to select the second operating channel before expiry or upon expiry of the first transmission opportunity.

21. The apparatus according to claim 20, wherein the apparatus is configured to select the second operating channel upon a slot boundary of an ongo ing transmission.

22. The apparatus according to claim 20, wherein the apparatus is configured to select the second operating channel upon a frame boundary of an on going transmission.

23. The apparatus according to any of claims 19 to 22, wherein the appa ratus is configured to initiate transmission on the second operating channel upon ex piry of the first transmission opportunity.

24. The apparatus according to any of claims 19 to 23, wherein the chan nel availability monitoring comprises clear channel assessment.

25. The apparatus according to any of claims 19 to 24, wherein the appa ratus is configured to randomly select an available operating channel in response to receiving an indication that more than one channel is available.

26. The apparatus according to any of claims 19 to 25, wherein the appa ratus is configured to support full duplex communication to enable performing chan nel availability monitoring while transmitting the data.

27. The apparatus according to any of claims 19 to 26, wherein apparatus is further configured to hand the transmission opportunity over to a responding de vice while performing the channel availability monitoring.

28. The apparatus according to any of claims 19 to 27, wherein the appa ratus is configured to provide different scheduling for different operating channels included in the set of second operating channels.

29. The apparatus according to any of claims 19 to 28, wherein apparatus is configured to inform a responding device about the set of second operating chan nels.

30. The apparatus according to any of claim 19 to 29, wherein the first op- erating channel and the second operating channel are provided on an unlicensed spectrum.

31. The apparatus according to claim 30, wherein the unlicensed spec- trum comprises a band allocated for time division duplex operation.

32. The apparatus according to any of claims 19 to 31, wherein the appa ratus is further configured to determine a channel specific start time for channel availability monitoring on a second operating channel.

33. The apparatus according to any of claims 19 to 32, wherein the appa ratus is a base station.