WO2018141377A1

WO2018141377A1 - Method, system and apparatus

Info

Publication number: WO2018141377A1
Application number: PCT/EP2017/052128
Authority: WO
Inventors: Timo Erkki Lunttila; Kari Juhani Hooli
Original assignee: Nokia Technologies Oy
Priority date: 2017-02-01
Filing date: 2017-02-01
Publication date: 2018-08-09

Abstract

A method comprises receiving at a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal. From the reference signal channel state information CSI is determined. A grant-less report comprising the CSI is transmitted to an access point on a candidate subframe for grant-less uplink transmission only if the candidate subframe is within a first given time period with respect to the transmission opportunity.

Description

Title

METHOD, SYSTEM AND APPARATUS Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to a method and apparatus for use in a network which may operate in so-called unlicensed bands.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations/access points and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user is often referred to as user equipment (UE). A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station or access point, and transmit and/or receive communications on the carrier. The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). An example of attempts to solve the problems associated with the increased demands for capacity is an architecture that is known as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. LTE is being standardized by the 3rd Generation Partnership Project (3GPP).

In order to increase the available spectrum, it has been proposed to use the unlicensed spectrum using for example some aspects of UTRAN and/or LTE technology. Summary

According to an aspect, there is provided a method comprising: receiving at a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; determining channel state information from said received reference signal; and causing a grant-less report comprising said determined channel state information to be transmitted to an access point on a candidate subframe for grant-less uplink transmission only if said candidate subframe is within a first given time period with respect to said transmission opportunity.

The information about candidate subframes may be received in advance of said information about the transmission opportunity and said reference signal.

The method may comprise receiving at said user device activation information to enable said grant-less report comprising said determined channel state information.

The activation information may comprise at least one of: an indication of one or more cells for which said channel state information is to be reported; an indication of a modulation and coding scheme to be used for transmitting of said grant-less report; and an indication of one or more physical resource blocks to be used for transmitting of said grant-less report.

The causing may comprising causing said grant-less uplink report to be transmitted on an unlicensed band.

The first given time period may comprise an integer number of sub frames after a downlink subframe associated with said transmission opportunity. The information about candidate subframes may comprise information defining said integer number of subframes.

The downlink subframe associated with said transmission opportunity may comprise a downlink subframe comprising said reference signal.

The grant-less uplink report may comprise an aperiodic channel state information report.

The method may comprise causing an uplink shared channel to be transmitted and causing said grant-less uplink report to be transmitted on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel.

The method may comprise receiving at said user device information defining at least one of said first and second given time periods.

The method may comprise causing grant-less uplink report presence information to be transmitted. The method may comprise performing a listen before talk procedure before causing said transmission of said grant less uplink report, whereby only if there is an available channel, causing said transmission of said grant less uplink report. One or more of cyclic shift hopping, bit scrambling, symbol scrambling, bit interleaving, and a demodulation reference signal sequence for a transmission of said grant-less uplink report is independent of a subframe in which said grant less uplink report is transmitted.

According to another aspect, there is provided an apparatus in a user equipment comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; determine channel state information from said received reference signal; and cause a grant-less report comprising said determined channel state information to be transmitted to an access point on a candidate subframe for grant-less uplink transmission only if said candidate subframe is within a first given time period with respect to said transmission opportunity.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive activation information to enable said grant-less report comprising said determined channel state information. The activation information may comprise at least one of: an indication of one or more cells for which said channel state information is to be reported; an indication of a modulation and coding scheme to be used for transmitting of said grant-less report; and an indication of one or more physical resource blocks to be used for transmitting of said grant-less report.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause said grant-less uplink report to be transmitted on an unlicensed band. The first given time period may comprise an integer number of sub frames after a downlink subframe associated with said transmission opportunity.

The information about candidate subframes may comprise information defining said integer number of subframes.

The downlink subframe associated with said transmission opportunity may comprise a downlink subframe comprising said reference signal. The grant-less uplink report may comprise an aperiodic channel state information report.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause an uplink shared channel to be transmitted and cause said grant-less uplink report to be transmitted on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive at said user device information defining at least one of said first and second given time periods.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause grant-less uplink report presence information to be transmitted.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to perform a listen before talk procedure before causing said transmission of said grant less uplink report, whereby only if there is an available channel, cause said transmission of said grant less uplink report.

One or more of cyclic shift hopping, bit scrambling, symbol scrambling, bit interleaving, and a demodulation reference signal sequence for a transmission of said grant-less uplink report may be independent of a subframe in which said grant less uplink report is transmitted.

According to another aspect, there is provided an apparatus in a user device comprising: means for receiving information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; means for determining channel state information from said received reference signal; and means for causing a grant-less report comprising said determined channel state information to be transmitted to an access point on a candidate subframe for grant-less uplink transmission only if said candidate subframe is within a first given time period with respect to said transmission opportunity.

The receiving means may be for receiving activation information to enable said grant- less report comprising said determined channel state information. The activation information may comprise at least one of: an indication of one or more cells for which said channel state information is to be reported; an indication of a modulation and coding scheme to be used for transmitting of said grant-less report; and an indication of one or more physical resource blocks to be used for transmitting of said grant-less report.

The causing means may be for causing said grant-less uplink report to be transmitted on an unlicensed band.

The first given time period may comprise an integer number of sub frames after a downlink subframe associated with said transmission opportunity.

The information about candidate subframes may comprise information defining said integer number of subframes. The downlink subframe associated with said transmission opportunity may comprise a downlink subframe comprising said reference signal.

The causing means may be for causing an uplink shared channel to be transmitted and causing said grant-less uplink report to be transmitted on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel.

The receiving means may be for receiving information defining at least one of said first and second given time periods. The causing means may be for causing grant-less uplink report presence information to be transmitted.

The apparatus may comprise means for performing a listen before talk procedure before causing said transmission of said grant less uplink report, whereby only if there is an available channel, does the causing means cause said transmission of said grant less uplink report.

According to another aspect, there is provided a method comprising: transmitting to a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; and receiving a grant-less report comprising channel state information on a candidate subframe for grant-less uplink transmission within a first given time period with respect to said transmission opportunity. The information about candidate subframes may be transmitted in advance of said information about the transmission opportunity and said reference signal. The method may comprise transmitting to the user device activation information to enable said grant-less report comprising said determined channel state information.

The method may comprise receiving said grant-less uplink report on an unlicensed band.

The method may comprise receiving an uplink shared channel and receiving said grant-less uplink report on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel.

The method may comprise transmitting to said user device information defining at least one of said first and second given time periods. The method may comprise receiving grant-less uplink report presence.

According to another aspect, there is provided an apparatus in an access point comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: transmit to a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; and receive a grant-less report comprising channel state information on a candidate subframe for grant-less uplink transmission within a first given time period with respect to said transmission opportunity.

The information about candidate subframes may be transmitted in advance of said information about the transmission opportunity and said reference signal.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to transmit to the user device activation information to enable said grant-less report comprising said determined channel state information.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive said grant-less uplink report on an unlicensed band.

The grant-less uplink report may comprise an aperiodic channel state information report. The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive an uplink shared channel and receiving said grant-less uplink report on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to transmit to said user device information defining at least one of said first and second given time periods. The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive grant-less uplink report presence.

According to another aspect, there is provided an apparatus comprising: means for transmitting to a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; and means for receiving a grant-less report comprising channel state information on a candidate subframe for grant-less uplink transmission within a first given time period with respect to said transmission opportunity.

The information about candidate subframes may be transmitted in advance of said information about the transmission opportunity and said reference signal. The transmitting means may be for transmitting to the user device activation information to enable said grant-less report comprising said determined channel state information. The activation information may comprise at least one of: an indication of one or more cells for which said channel state information is to be reported; an indication of a modulation and coding scheme to be used for transmitting of said grant-less report; and an indication of one or more physical resource blocks to be used for transmitting of said grant-less report.

The receiving means may be for receiving said grant-less uplink report on an unlicensed band.

The receiving means may be for receiving an uplink shared channel and receiving said grant-less uplink report on a subframe usable by said user device for grant-less transmission within a given time period with respect to said uplink shared channel. The transmitting means may be for transmitting to said user device information defining at least one of said first and second given time periods.

The receiving means may be for receiving grant-less uplink report presence. In another aspect there is provided a computer program embodied on a non-transitory computer-readable storage medium, the computer program comprising program code for providing any of the above methods. In another aspect there is provided a computer program product for a computer, comprising software code portions for performing the steps of any of the previous methods, when said product is run.

A computer program comprising program code means adapted to perform the method(s) may be provided. The computer program may be stored and/or otherwise embodied by means of a carrier medium.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example communication system comprising a plurality of base stations and a plurality of communication devices; Figure 2 shows a schematic diagram of an example mobile communication device;

Figure 3 shows a communication system in which some embodiments may be provided; Figure 4 shows a schematic diagram of an example control apparatus;

Figures 5a and 5b shows examples of aperiodic channel state information transmission; and Figure 6 shows a flowchart of an example method. Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 2 to assist in understanding the technology underlying the described examples.

In a wireless communication system 100, such as that shown in Figure 1 , mobile communication devices or user equipment (UE) 102, 104, 1 05 are provided wireless access via at least one base station or similar wireless transmitting and/or receiving node or point. A base station is referred to as an eNodeB B (eNB) in LTE. Base stations are typically controlled by at least one appropriate controller apparatus, so as to enable operation thereof and management of mobile communication devices in communication with the base stations. The controller apparatus may be located in a radio access network (e.g. wireless communication system 1 00) or in a core network (CN) (not shown) and may be implemented as one central apparatus or its functionality may be distributed over several apparatus. The controller apparatus may be part of the base station and/or provided by a separate entity such as a Radio Network Controller. In Figure 1 control apparatus 108 and 109 are shown to control the respective macro level base stations 106 and 107. In some systems, the control apparatus may additionally or alternatively be provided in a radio network controller.

LTE systems may however be considered to have a so-called "flat" architecture, without the provision of RNCs; rather the (e)NB is in communication with a system architecture evolution gateway (SAE-GW) and a mobility management entity (MME), which entities may also be pooled meaning that a plurality of these nodes may serve a plurality (set) of (e)NBs. Each UE is served by only one MME and/or S-GW at a time and the (e) NB keeps track of current association. SAE-GW is a "high-level" user plane core network element in LTE, which may consist of the S-GW and the P-GW (serving gateway and packet data network gateway, respectively). The functionalities of the S- GW and P-GW are separated and they are not required to be co-located. In Figure 1 base stations 106 and 107 are shown as connected to a wider communications network 1 13 via gateway 1 12. A further gateway function may be provided to connect to another network.

The smaller base stations 1 16, 1 18 and 120 may also be connected to the network 1 1 3, for example by a separate gateway function and/or via the controllers of the macro level stations. The base stations 1 1 6, 1 18 and 120 may be pico or femto level base stations or the like. In the example, stations 1 1 6 and 1 18 are connected via a gateway 1 1 1 whilst station 120 connects via the controller apparatus 1 08. In some embodiments, the smaller stations may not be provided.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

A mobile device is typically provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto. The communication devices 102, 104, 105 may access the communication system based on various access techniques.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). A latest 3GPP based development is often referred to as the long term evolution (LTE) or LTE Advanced Pro of the Universal Mobile Telecommunications System (UMTS) radio-access technology. Other examples of radio access system comprise those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access). A base station can provide coverage for an entire cell or similar radio service area. Wireless communication systems may be licensed to operate in particular spectrum bands. A technology, for example LTE, may operate, in addition to a licensed band, in an unlicensed band. One technology for operating in unlicensed spectrum is Licensed- Assisted Access (LAA). Currently, a connection via a licensed band is maintained while using the unlicensed band with LAA technology. Standalone LTE operation on unlicensed spectrum has been considered. LTE standalone operation on unlicensed spectrum means that eNB/UE air interface relies solely on unlicensed spectrum without any carrier on licensed spectrum. An example of LTE standalone operation in unlicensed bands is the MulteFire technology specified by the MulteFire Alliance.

The target of the MulteFire technology is to create a new telecommunications system where LTE radio technology is used on an unlicensed radio band. Some embodiments may support regular LTE by extending LTE service into unlicensed radio band using for example a so-called MulteFire radio. However it should be appreciated that embodiments are not limited to a LTE type of cellular service, and could support e.g., a 3G radio service or a 5G radio service. Alternatively or additionally MulteFire may provide local internet connectivity and/or mobility within the MulteFire network. In some embodiments, this may be independent of any cellular operator and/or subscriber information module (SIM) card presence.

MulteFire radio may be independent of LTE radio presence in a licensed band. This contrasts with 3GPP specific unlicensed technologies like LAA, designed to operate on unlicensed band frequencies. By way of example only, MulteFire may operate in the same 5 GHz band in which Wi-Fi operates. Alternatively or additionally any other suitable frequency band may be used, e.g. 2.4 GHz band. MulteFire technology may be applied also to certain spectrum sharing scenarios, e.g. the 3.5 GHz band in US. Reference is made to Figure 3 which schematically shows a proposed MulteFire system. On the radio interface, MulteFire may rely on LTE technology. In some embodiments, there may be as few modifications as compared to LTE as possible. In the MulteFire system, user devices 2 such as previously described may be used. These user devices are referenced to as UE 2 Figure 3. These devices may be conventional user equipment. Alternatively or additionally conventional user equipment may be modified in order to operate with a MulteFire network. Alternatively or additionally user equipment configured to work specifically with a MulteFire network may be provided. The MulteFire system will use access points AP 4. These access points will be referred to as MF-AP in this document. In the MulteFire system, the radio interface may terminate on the UE 2 and on MF-AP 4 on network side. The access points MF-AP 4 may be connected to a backhaul 6. The backhaul 6 may be configured to connect to an IP network 8 or the like. The IP network 8 may be coupled to a cellular core network 10 or a dedicated core network 12. Thus, the MulteFire access point MF-AP 6 may be connected to conventional cellular core network 10, i.e. EPC (Evolved Packet Core). This is the LTE packet core. MulteFire deployment in such model may be referred to as EPC connected mode. In another embodiment, the access point MF-AP 6 may alternatively or additionally be connected to a MulteFire core network (MF CN) 12 that provides the necessary core network functions for MulteFire operations. This deployment model may be referred to as neutral host mode. The MulteFire CN may be as simple as possible in some embodiments. For example, in some embodiments, the MulteFire core network may be provided in one physical network equipment hardware. In some embodiments the MulteFire core network may be integrated into one or more MF-APs. Alternatively, the MulteFire CN can also be realized as a virtualized implementation. LAA and for example LTE-U, may provide licensed-assisted access to unlicensed spectrum while coexisting with other technologies and fulfilling the regulatory requirements. In LAA, unlicensed spectrum may be utilized to improve DL (downlink) throughput. In some arrangements, one or more LAA DL SCell (secondary cell) may be configured to an UE as part of DL CA (carrier aggregation) configuration, while the PCell (primary cell) is on licensed spectrum.

In some embodiments LAA may support UL (uplink) transmissions on unlicensed spectrum. For example, LAA PUSCH (physical uplink shared channel) transmissions may be supported. This is sometimes referred to as LTE eLAA.

In some jurisdictions, unlicensed technologies may need to abide by certain regulations, e.g. Listen-Before-Talk (LBT), in order to provide fair coexistence between LTE and other technologies such as Wi-Fi as well as between LTE operators. In unlicensed band operation, before being permitted to transmit, a user or an access point (such as eNodeB) may, depending on regulatory requirements, need to monitor a given radio frequency, i.e. carrier, for a short period of time to ensure the spectrum is not already occupied by some other transmission. This requirement is referred to as Listen-Before-Talk (LBT). The requirements for LBT vary depending on the geographic region: e.g. in the US such requirements do not exist, whereas in e.g. Europe and Japan the network elements operating on unlicensed bands need to comply with LBT requirements. Moreover, LBT may be needed in order to guarantee co-existence with other unlicensed band usage in order to enable e.g. fair co-existence with Wi-Fi also operating on the same spectrum and/or carriers.

Some embodiments relate to the transmission of UL control information (UCI), in particular Aperiodic CSI (channel state information) reports, on unlicensed spectrum subject to Listen-Before-Talk rules. This may for example be provided in a MulteFire environment and/or in relation 3GPP LTE Licensed Assisted Access enhancements. Some embodiments may provide support for autonomous (or grant-less UL, GUL) uplink transmissions in MulteFire and/or eLAA.

In some embodiments, grant-less, or autonomous PUSCH, where the UE is allowed to transmit on UL on preconfigured resources without having to receive a separate explicit UL grant for each transmission may be supported. Aperiodic CSI reporting on unlicensed spectrum when applying grant-less UL operation may be provided.

GUL transmissions may reduce latency related to UL transmissions. Latency becomes an issue in particular when operating on unlicensed spectrum since each Listen- Before-Talk procedure may delay channel access for an extended period of time. Increased latency may reduce effective throughput as the TCP/IP protocol may place emphasis on low latency especially at the beginning of session of data packets. As an example, in the case of UL data transmissions in normal MulteFire operation, the UE will first send a scheduling request SR to the eNodeB to indicate it has data to transmit in its buffer. Since SR resources are a part of a transmission opportunity (TXOP) acquired by the eNodeB, this step will involve: 1 ) a first LBT procedure by the eNodeB to acquire a TXOP to which the MF- sPUCCH (Physical uplink control channel) and SR resources belong to, and

2) another LBT by the UE immediately before transmitting the SR on MF- sPUCCH.

Next, after receiving the SR the eNodeB will need to perform a third LBT procedure, and after succeeding, the eNodeB may then request with an UL grant the UE to transmit UL data or for example an Aperiodic CSI report. Prior to transmitting, the UE will need to perform a fourth LBT. In an environment where there are multiple nodes contending for the same channel, each LBT procedure will inevitable increase latency related to channel access.

With GUL, UL resources are granted for the UE on a long term basis, using e.g. RRC (radio resource control) configuration, or SPS (semi persistent scheduling). This allows the UE to get its UL signals transmitted without a need for the eNB to clear the LBT twice (step 1 & 3), and without the UE having to transmit an SR (step 2).

On the other hand, UL data transmission by the UE will typically trigger some DL data transmissions too. Therefore it may be beneficial for the eNodeB to be able to get an Aperiodic CSI rapidly, so that DL link adaptation including e.g. modulation and coding scheme setting and MIMO pre-coder selection can be adjusted as necessary. Pseudo- periodic CSI reporting (for example supported in MulteFire release 1 .0 specifications) may allow maintaining CSI for UEs without PUSCH transmissions. On the other hand, pseudo-periodic CSI may be limited to wideband reporting modes, and therefore cannot provide very accurate CSI.

Some embodiments may facilitate Aperiodic CSI (A-CSI) reporting with GUL transmissions.

A set of rules may be provided according to which Aperiodic CSI reports are transmitted on an unlicensed band when applying GUL operation. In some embodiments, the timing instances when A-CSI occurs will depend on the timing of the eNodeB acquired TXOPs.

In one embodiment, the UE includes an Aperiodic CSI report into the first (or n first, or every) GUL transmission occurring in a TXOP acquired by the eNodeB, and/or up to x subframes after that.

If a GUL subframe occurs more than x subframes after the TXOP (or x subframes after the end of the DL burst), A-CSI is not reported, in some embodiments, x may be defined relative to the last complete DL subframe or with respect to a specific downlink frame. For example, the specific downlink frame may be the subframe carrying the reference signals used for the CSI measurement. This may be the case for example with CSI-RS, which may not be present in every DL subframe, in some embodiments. The value of x may be any suitable number of subframes for example between 1 and 20. By way of example only, the value of x may be 5, 10 or 20 subframes. Of course in other embodiments, x may take any other suitable value.

The measurements for the Aperiodic CSI reports need to be performed during the DL part of a TXOP, and reporting A-CSI long after the measurement has been done provides no benefits as the report is likely outdated already.

The value of x may be predetermined (e.g. fixed in the specifications), configurable via e.g. RRC signalling or determined in the UE. Where x is configurable, this may be set dependent on one or more of the anticipated network load, current network load, radio conditions in the cell, interference and volatility of network conditions. This may be configured by the eNB.

The eNB may configure the occurrences (for example one or more of periodicity, subframe offset, and number of consecutive subframes) for the GUL subframes that may carry A-CSI, such that those are different from the generic GUL subframes. For example, the eNB may want to e.g. facilitate some degree of time domain multiplexing of CSI reports for different users, such that not all the UEs would transmit their A-CSI in the same subframes, even if the GUL subframes allowed for generic use would be the same. The GUL subframes for A-CSI may be e.g. a subset of all GUL subframes (every 2nd, 3rd, etc.) A-CSI is transmitted in such a subframe only if UE transmits UL-SCH (uplink shared channel) in the same subframe or has transmitted the UL-SCH during y preceding subframes. In other words A-CSI reporting may be quasi-periodic as it is conditioned on UL-SCH transmission. Transmitting the A-CSI in GUL subframes only when there is also UL data in the UL-SCH can help in avoiding unnecessary A-CSI transmissions, and thereby reduce the loading of GUL resources. In an alternative embodiment, the A-CSI being transmitted after there has been at least one data-only GUL transmission may be an alternative to tying the decision whether to transmit A-CSI according to x (and DL transmission). The eNB may configure the A-CSI reporting mode and the reported DL carrier(s) for the GUL separately from that of dynamically triggered A-CSI reports. The indication of the reported carriers can be conveyed e.g. in the SPS UL grant activating the GUL resource. Similarly, SPS UL grant may be used to activate / deactivate GUL A-CSI reporting.

The A-CSI reporting mode, and optionally the reported carriers may be configured via RRC signalling. In case of carrier aggregation, RRC configuration defines how the bits (2 or 3) in the SPS UL grant activating GUL-A-CSI transmission should be interpreted. One example below:

Bits in the UL grant activating GUL transmission:

00 = do not report A-CSI in GUL subframe

01 = report A-CSI for the primary cell

10 = report A-CSI for the 1 st set of RRC configured DL carriers

1 1 = report A-CSI for the 2nd set of RRC configured DL carriers

Each set of RRC configured DL carriers (for 1 0 and 1 1 ) can be configured e.g. with a bitmap, having as many bits as there are carriers, where each toggled bit indicates that A-CSI should be reported for the corresponding carrier. It should be appreciated that the bit values above are by way of example. One or more of the options above may be omitted. In another, alternative embodiment, after transmitting the GUL PUSCH data in a first GUL subframe, the UE transmits the A-CSI in the next available GUL subframe without any UL-SCH data. This option may be advantageous if for example the resources available for GUL transmission are limited in size such that both the A-CSI and UL SCH data would not fit together into same subframe. The GUL PUSCH data may be any data that the UE wants to transmit to the eNodeB without the eNodeB specifically requesting that data. The GUL PUSCH data may be any UE-initiated UL data transmission.

With a GUL transmission a UE does not need to send a SR first, but instead can send data directly on the preconfigured resources.

Reference is made to Figure 6 which it shows one example method according to an embodiment. Figure 6 will be described in conjunction with Figures 5a and 5b. Aperiodic CSI reporting on GUL PUSCH resources is illustrated in Figure 5a. The specific cases when A-CSI is not reported are shown in Figure 5b, to illustrate the differences in comparison to periodic CSI reporting.

In step S1 , the access point will perform a LBT procedure to acquire a transmission opportunity TXOP.

In step S2, the access point will transmit information about the TXOP to the user equipment. The TXOP information may take any suitable format. For example, the TXOP information may comprise one or more of start information, end information and number of subframes or frames. In step S2, the access point will also transmit a reference signal or the like to the user equipment. This reference signal is, as described later, measured by the user equipment to determine the CSI information. With reference to Figure 5a and 5b, the downlink frames are referenced 510 and represent information which is transmitted from the access point to the user equipment. This may comprise the information transmitted for example in step S2. In step S3a, the user equipment will transmit a UL SCH on a GUL PUSCH.

The UE will have already received a configuration for GUL subframes, including the candidate subframes for A-CSI transmission. The UE may have received basic configuration (e.g. GUL subframes, potentially separately for data and A-CSI) via RRC signalling. The UE may have received activation (or deactivation/reactivation/adjustment) via downlink control information (DCI) on the PDCCH (physical downlink control channel).The activation signalling may also include one or more bit to indicate whether the UE should report A-CSI in the GUL subframes, and/or for which carriers the A-CSI should be reported. The RRC configuration and activation will have already logically come before the beginning of the method of Figure 6, i.e. before step S1 since they are a prerequisite for any GUL transmissions. In some embodiments, the A-CSI can be transmitted within y subframes after the UL-SCH. This can be any suitable value between 1 and 20ms, for example 5, 10 or 20ms, and may be either predetermined or received as a part of the basic configuration before S1 . Other values of y can or course be used.

In step S3b, the user equipment will measure the received reference signal and determine the CSI information which is to be transmitted to the access point. It should be appreciated that the steps S3a and S3b can take place at the same time or in any order. The UE may also omit S3a and transmit Aperiodic CSI without any SCH.

With reference to Figures 5a and 5b, the uplink SCH which is transmitted on the GUL PUSCH is referenced 506. As can be seen, this is transmitted within x subframes of the downlink transmission.

In step S4, the user equipment determines which of the candidate subframes is to be used for the A-CSI. In step S5, it is determined whether a given candidate subframe for the A-CSI satisfies the criteria for the transmission timing of the A-CSI. For example, the criteria may be that the A-CSI is transmitted on the GUL PUSCH within x subframes after the downlink frames. In another example, the criteria may be that the A-CSI is transmitted on the GUL PUSCH within y subframes after the UL-SCH. This can be any suitable value between 1 and 20ms, for example 5, 10 or 20ms. Other values of y can or course be used. This criteria is referenced 502 in Figures 5a and 5b. Furthermore, step S5 may involve an LBT procedure performed by the UE, and A-CSI is transmitted only if the channel is observed to be clear immediately prior to the intended transmission of A- CSI. This criteria is referenced 500 in Figures 5a and 5b.

In some embodiments, steps S4 and S5 are performed together as a single method step. If it is determined that the timing criteria for the transmission of the A-CSI are satisfied, then the next step is step S6 in which the A-CSI is transmitted at the determined candidate subframe.

If the criteria for the candidate subframe of the A-CSI is not satisfied, then the next step is step S7 where the A-CSI is not transmitted.

In one modification, in step S5 a candidate subframe is only determined if it satisfies the required criteria. This means that the step S7 can be omitted. As shown in Figure 5a, the determined candidate subframe for A-CSI is within x subframes and accordingly is transmitted. The transmitted A-CSI is referenced 508.

In contrast, in Figure 5b, the A-CSI is determined, as referenced 508b to be transmitted in a candidate subframe within y subframes after the UL-SCH but does not satisfy the criteria of being within x subframes of the downlink subframes. Accordingly, the A- CSI is not transmitted in the arrangement shown in figure 5b. A further scheduling opportunity 508b is shown which satisfies the criteria of being within x subframes of a subsequent downlink transmission but does not satisfy the requirement to be within y subframes of the UL-SCH. It should be appreciated that this method can be modified to take into account any of the described alternatives. For example, it may be enough that the candidate subframe is either within the range of x or y, and not both.

Some handling for error cases will now be described. An eNB may be uncertain of whether or not an A-CSI is included in a GUL PUSCH. For example, an eNB may fail to detect the first GUL PUSCH transmission due to collision. In most collision cases the eNB can identify the transmitting UEs based on a DMRS (demodulation reference signal) or preamble. However, in a small portion of collisions eNB does not identify transmitting UEs. In those cases, the eNB may have different understanding to the UE as to whether or not the A-CSI is included in the GUL PUSCH (eNB assumes that A- CSI is included in the transmission, while the UE may have transmitted that already in preceding GUL PUSCH).

Due to the payload size of A-CSI, which is often in the range of 50 - 100 bits per carrier, puncturing A-CSI on PUSCH may not be a preferred solution and A-CSI needs to be multiplexed with the UL-SCH on PUSCH. As consequence, in the case where the eNB and UE have a different understanding of the presence of the A-CSI, eNB will not only lose A-CSI, but also fail to decode PUSCH TB (transport block) and corrupt HARQ (hybrid automatic repeat request) buffer content. The probability of that kind of error should be low, e.g. 1 %, but does not need to be extremely low.

It may be that UE identification based on DMRS or GUL preamble in the case of collision provides a sufficiently low error case probability. If this is deemed to be insufficient, an A-CSI presence bit may be included in the data-associated control signalling transmitted on GUI PUSCH. This may be feasible due to a relatively small payload. The signalling may mapped either on predetermined resource elements, and the PUSCH is mapped around it, or is punctured to PUSCH on predetermined resource elements.

Since the UE may need to prepare the A-CSI report before the UE knows the outcome of the LBT procedure, the signal generation may not depend on the index of the subframe in which the transmission takes place. LBT is carried out immediately before the transmission should happen in some embodiments. The signal generation refers to for example selection or scrambling of the reference signal sequence, which in normal (licensed band LTE) is subframe dependent. However, here it would be preferable to keep it time invariant, since depending on the outcome of LBT, the signal transmission may need to be postponed. This may include one or more of the following features:

DMRS sequence does not depend on the subframe index

Cyclic shift hopping (if applied) does not depend on the subframe index Bit/symbol scrambling (if applied) does not depend on the subframe index · Bit interleaving (if applied) does not depend on the subframe index

Some embodiments may provide one or more advantages.

For example, the eNodeB or access point may be able to get an up-to-date Aperiodic CSI report in the case of grant-less UL operation,

For example, the latency with unlicensed band operation may be minimised or at least reduced. In unlicensed spectrum operation, the term transmission opportunity (TxOP) is used to refer to a burst.

It should be understood that each block of the flowchart of the Figures and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry.

It is noted that whilst embodiments have been described in relation to one example of an unlicensed spectrum network, similar principles maybe applied in relation to other examples of networks. It should be noted that other embodiments may be based on other cellular technology other than LTE or on variants of LTE. For example, some embodiments may be used with so-called 5G New Radio. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

The method may be implemented in entities on a mobile device as described with respect to figure 2 or control apparatus as shown in Figure 4. Figure 6 shows an example of a control apparatus provided in a base station or access point. The control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head. For example the control apparatus 300 or processor 201 can be configured to execute an appropriate software code to provide the control functions.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. The embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non- limiting examples. Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate. The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims. Indeed there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1 . A method comprising:

receiving at a user device information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal; determining channel state information from said received reference signal; and

causing a grant-less report comprising said determined channel state information to be transmitted to an access point on a candidate subframe for grant- less uplink transmission only if said candidate subframe is within a first given time period with respect to said transmission opportunity.

2. A method as claimed in claim 1 , wherein said information about candidate subframes is received in advance of said information about the transmission opportunity and said reference signal.

3. A method according to claim 1 or 2, comprising receiving at said user device activation information to enable said grant-less report comprising said determined channel state information.

4. A method as claimed in claim 3, wherein said activation information comprises at least one of:

an indication of one or more cells for which said channel state information is to be reported;

an indication of a modulation and coding scheme to be used for transmitting of said grant-less report; and

an indication of one or more physical resource blocks to be used for transmitting of said grant-less report.

5. A method as claimed in any preceding claim, wherein said causing comprising causing said grant-less uplink report to be transmitted on an unlicensed band.

6. A method as claimed in claim, wherein said first given time period comprises an integer number of sub frames after a downlink subframe associated with said transmission opportunity.

7. A method as claimed in claim 6, wherein said information about candidate subframes comprises information defining said integer number of subframes.

8. A method as claimed in claim 6 or 7, wherein said downlink subframe associated with said transmission opportunity comprises a downlink subframe comprising said reference signal.

9. A method as claimed in any preceding claim, wherein said grant-less uplink report comprises an aperiodic channel state information report.

10. A method as claimed in any preceding claim, comprising causing an uplink shared channel to be transmitted and causing said grant-less uplink report to be transmitted on a subframe usable by said user device for grant-less transmission within a second given time period with respect to said uplink shared channel.

1 1 . A method as claimed in any preceding claim, comprising receiving at said user device information defining at least one of said first and second given time periods.

12. A method as claimed in any preceding claim, further comprising causing grant- less uplink report presence information to be transmitted.

13. A method as claimed in any preceding claim, comprising performing a listen before talk procedure before causing said transmission of said grant less uplink report, whereby only if there is an available channel, causing said transmission of said grant less uplink report.

14. A method as claimed in any preceding claim, wherein one or more of cyclic shift hopping, bit scrambling, symbol scrambling, bit interleaving, and a demodulation reference signal sequence for a transmission of said grant less uplink report is independent of a subframe in which said grant less uplink report is transmitted.

15. A computer program comprising computer executable code which when run on one or more processors causes the method of any preceding claim to be performed.

16. An apparatus in a user equipment comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

receive information about candidate subframes for grant-less transmission of channel state information, information about a transmission opportunity and a reference signal;

determine channel state information from said received reference signal; and cause a grant-less report comprising said determined channel state information to be transmitted to an access point on a candidate subframe for grant-less uplink transmission only if said candidate subframe is within a first given time period with respect to said transmission opportunity.