WO2017148733A1

WO2017148733A1 - Method, system and apparatus

Info

Publication number: WO2017148733A1
Application number: PCT/EP2017/053854
Authority: WO
Inventors: Esa Tapani Tiirola; Kari Juhani Hooli; Timo Erkki Lunttila
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2016-03-01
Filing date: 2017-02-21
Publication date: 2017-09-08

Abstract

There is provided a method comprising receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, determining whether to transmit uplink control information based on said downlink control information and, if so, determining at least one control channel resource for transmission of uplink control information based on the downlink control information and causing transmission of uplink control information using the at least one determined control channel resource.

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

In a first aspect there is provided a method comprising receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, determining whether to transmit uplink control information based on said downlink control information and, if so, determining at least one control channel resource for transmission of uplink control information based on the downlink control information and causing transmission of uplink control information using the at least one determined control channel resource.

The downlink control information may comprises a plurality of indices. The first user device may be associated with a respective one of the plurality of indices. Each of the plurality of indices may have an associated index value.

Each index value may comprise an indication of whether to cause uplink control information transmission or reserve control channel resource.

The index value associated with the respective one of the plurality of indices may comprise an indication of the at least one control channel resource for transmission of the uplink control information.

The at least one control channel resource for transmission of the uplink control information may be preconfigured at the user device.

The index value may comprise two bits. At least one index value may comprise an indication of at least one control channel resource for transmission of the uplink control information.

The method may comrpise determining the at least one control channel resource for transmission of uplink control information based on the index values associated with the other of the plurality of indices.

The at least one control channel resource may be determined based on a starting resource index defined for the downlink control information.

The downlink control information may be coded using the at least one control channel radio network temporary identifier.

The uplink control information may comprise at least one hybrid automatic repeat request acknowledgement.

The control channel may be an enhanced physical uplink control channel.

The method may comprise causing transmission of the uplink control information a predetermined time after receiving the downlink control information.

The downlink control information may comprise timing information for uplink control information transmission. In a second aspect there is provided a method comprising providing, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information and receiving transmission of uplink control information using the at least one determined control channel resource.

Each index value may comprise an indication of whether to cause uplink control information transmission or reserve control channel resource. The index value associated with the respective one of the plurality of indices may comprise an indication of the at least one control channel resource for transmission of the uplink control information.

The index value may comprise two bits.

At least one index value may comprise an indication of at least one control channel resource for transmission of the uplink control information.

The at least one control channel resource for transmission of uplink control information may be determined based on the index values associated with the other of the plurality of indices.

The at least one control channel resource may be determined based on a starting resource index defined for the downlink control information. The downlink control information may be coded using the at least one control channel radio network temporary identifier.

The control channel may be an enhanced physical uplink control channel.

The method may comprise receiving the uplink control information a predetermined time after receiving the downlink control information.

The downlink control information may comprise timing information for uplink control information transmission.

In a third aspect there is provided an apparatus, said apparatus comprising means for receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, means for determining whether to transmit uplink control information based on said downlink control information and means for, if so, determining at least one control channel resource for transmission of uplink control information based on the downlink control information and means for causing transmission of uplink control information using the at least one determined control channel resource.

The downlink control information may comprises a plurality of indices. The first user device may be associated with a respective one of the plurality of indices. Each of the plurality of indices may have an associated index value. Each index value may comprise an indication of whether to cause uplink control information transmission or reserve control channel resource.

The at least one control channel resource for transmission of the uplink control information may be preconfigured at the user device. The index value may comprise two bits.

At least one index value may comprise an indication of at least one control channel resource for transmission of the uplink control information. The apparatus may comrpise means for determining the at least one control channel resource for transmission of uplink control information based on the index values associated with the other of the plurality of indices.

The downlink control information may be coded using the at least one control channel radio network temporary identifier. The uplink control information may comprise at least one hybrid automatic repeat request acknowledgement. The control channel may be an enhanced physical uplink control channel.

The apparatus may comprise means for causing transmission of the uplink control information a predetermined time after receiving the downlink control information.

In a fourth aspect there is provided an apparatus, said apparatus comprising means for providing, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information and means for receiving transmission of uplink control information using the at least one determined control channel resource.

The index value may comprise two bits.

The at least one control channel resource for transmission of uplink control information may be determined based on the index values associated with the other of the plurality of indices. The at least one control channel resource may be determined based on a starting resource index defined for the downlink control information. The downlink control information may be coded using the at least one control channel radio network temporary identifier.

The control channel may be an enhanced physical uplink control channel.

The apparatus may comprise means for receiving the uplink control information a predetermined time after receiving the downlink control information.

In a fifth aspect there is provided an apparatus, said apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to receive, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, determine whether to transmit uplink control information based on said downlink control information and, if so, determine at least one control channel resource for transmission of uplink control information based on the downlink control information and cause transmission of uplink control information using the at least one determined control channel resource. The downlink control information may comprises a plurality of indices. The first user device may be associated with a respective one of the plurality of indices. Each of the plurality of indices may have an associated index value.

Each index value may comprise an indication of whether to cause uplink control information transmission or reserve control channel resource. The index value associated with the respective one of the plurality of indices may comprise an indication of the at least one control channel resource for transmission of the uplink control information. The at least one control channel resource for transmission of the uplink control information may be preconfigured at the user device.

The apparatus may be configured to determine the at least one control channel resource for transmission of uplink control information based on the index values associated with the other of the plurality of indices.

The control channel may be an enhanced physical uplink control channel.

The apparatus may be configured to cause transmission of the uplink control information a predetermined time after receiving the downlink control information.

In a sixth aspect there is provided an apparatus, said apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to provide, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information and receive transmission of uplink control information using the at least one determined control channel resource.

The index value may comprise two bits.

The apparatus may be configured to receive the uplink control information a predetermined time after receiving the downlink control information.

In a seventh aspect there is provided a computer program embodied on a non-transitory computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, determining whether to transmit uplink control information based on said downlink control information and, if so, determining at least one control channel resource for transmission of uplink control information based on the downlink control information and causing transmission of uplink control information using the at least one determined control channel resource. The downlink control information may comprises a plurality of indices. The first user device may be associated with a respective one of the plurality of indices. Each of the plurality of indices may have an associated index value.

The index value may comprise two bits.

At least one index value may comprise an indication of at least one control channel resource for transmission of the uplink control information. The process may comrpise determining the at least one control channel resource for transmission of uplink control information based on the index values associated with the other of the plurality of indices.

The uplink control information may comprise at least one hybrid automatic repeat request acknowledgement. The control channel may be an enhanced physical uplink control channel.

The process may comprise causing transmission of the uplink control information a predetermined time after receiving the downlink control information. The downlink control information may comprise timing information for uplink control information transmission.

In an eighth aspect there is provided a computer program embodied on a non-transitory computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising providing, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information and receiving transmission of uplink control information using the at least one determined control channel resource.

The index value may comprise two bits.

The control channel may be an enhanced physical uplink control channel.

The process may comprise receiving the uplink control information a predetermined time after receiving the downlink control information.

In a ninth aspect there is provided a computer program product for a computer, comprising software code portions for performing the steps the method of the first and second aspect when said product is run on the computer. 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 bandwidth occupancy with one out of ten interlaces and cluster size of 1 PRB; Figure 5 shows a schematic diagram of DCI format 3;

Figure 6 shows a flowchart of an example method according to some embodiments;

Figure 7 shows a schematic diagram of a DCI format according to some embodiments;

Figure 8 shows a schematic diagram of a DCI according to some embodiments; Figure 9 shows a schematic diagram of a DVI according to some embodiments; Figure 10 shows a schematic diagram of an example control apparatus. 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, 105 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 100) 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 112. 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 13, for example by a separate gateway function and/or via the controllers of the macro level stations. The base stations 1 16, 118 and 120 may be pico or femto level base stations or the like. In the example, stations 116 and 1 18 are connected via a gateway 1 1 1 whilst station 120 connects via the controller apparatus 108. 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 proposal for operating in unlicensed spectrum is Licensed- Assisted Access (LAA). Currently, it is proposed with LAA that a connection via a licensed band is maintained while using the unlicensed band.

LAA with 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 proposed 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 and LTE-U, 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. MuLTEfire technology may be applied also to certain spectrum sharing scenarios, e.g. the 3.5 GHz band in US. It should be appreciated that MuLTEfire is not limited to cellular operation. A MuLTEfire network may be operated by third party, invisible and unknown to UE. The MuLTEfire network may provide services for different service providers. In some embodiments, the UE may have one or more subscriptions only with the service providers (PSPs, mobile operators) and not the third party operator of the MuLTEfire network. The mobile operator service may be identified by an associated PLMN (public land mobile network) value.

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 in Figure 3. These devices may be conventional user equipment which are configured and/or able to be used with Wi-Fi. 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. When the MuLTEfire network is deployed with MuLTEfire core network, the network set up may use aspects of a typical Wi-Fi deployment. In some jurisdictions or regions, unlicensed technologies may need to abide by certain regulations, e.g. requiring use of Listen-Before-Talk (LBT) procedure, in order to provide fair coexistence between LTE and other technologies such as Wi-Fi, as well as between LTE operators. In LTE operation on unlicensed carriers, depending on the regulatory rules, the UE may need to perform a clear channel assessment (CCA) or listen-before-talk (LBT) procedure prior to any uplink (UL) transmission. Some exceptions may exist though. In some regions, transmission of ACK/NACK feedback may be possible without LBT when immediately following a downlink (DL) transmission (similar to WiFi operation) For example, short Control Signaling (SCS) rules defined for Europe by ETSI allow for transmission of control signaling with a duty cycle of no more than 5% over 50 ms period without performing LBT. In some regions, scheduled UL transmissions may in general be allowed without LBT, when the transmission follows directly a DL transmission before which the eNodeB has performed LBT and total transmission time covering both DL and UL is limited by the maximum Tx burst time defined by the regulator.

One option for uplink resource allocation in operation on unlicensed spectrum, e.g., MulteFire, may be based on block interleaved frequency division multiple access (B-IFDMA) as shown in Figure 4. In the example shown in Figure 4, each interlace consists of ten uniformly spaced resource blocks. The example design of Figure 4 is based on ten 1 -PRB interlaces at 20 MHz bandwidth. The minimum bandwidth allocation at 20 MHz bandwidth corresponds to 10 PRBs. It is possible to divide a B-IFDMA interlace into smaller resource units, e.g. by means of code division multiplexing or interleaved frequency division multiple access (IFDMA) within each cluster.

Two types of physical uplink control channel (PUCCH) formats may be supported in

MuLTEfire. The first PUCCH format may be referred to as short PUCCH (sPUCCH) and the second as enhanced PUCCH (ePUCCH). sPUCCH refers to a PUCCH structure occupying one B-IFDMA interlace for a duration of a few symbols (such as 4 symbols). The time duration of sPUCCH may be up to 4 symbols. Short PUCCH is time-domain multiplexed with physical uplink shared channel (PUSCH) so that sPUCCH precedes PUSCH. Short PUCCH may support multiple Short PUCCH formats. For example, there may be a Short PUCCH format designed for transmission of multiple hybrid automatic repeat request acknowledgments (HARQ-ACK) bits, and another Short PUCCH format designed for transmission of physical random access channel (PRACH), scheduling request (SR), or sounding reference signal (SRS). That is, sPUCCH may be used for HARQ-ACK, SR, random access (RA) preamble, SRS and cahnnel state information (CSI) and be available at least at the end of each DL Tx burst.

Multiple formats of sPUCCH may be optimized for different payload sizes. Payload size for HARQ-ACK and/or CSI may be limited due to UL coverage. Two flavours of sPUCCH based on a similar design may be defined as dynamic sPUCCH and periodic sPUCCH (utilising anchor/non-anchor subframes). sPUCCH may have two triggering mechanisms. Dynamic sPUCCH may be triggered by a common physical downlink control channel (C-PDCCH), e.g. a PDCCH control message that is intended for multiple (e.g. all) users in the cell. HARQ-ACK has predefined time relation with DL subframes where the DL grants are transmitted. Periodic sPUCCH locations may be configured by eNB and fixed in time Enhanced PUCCH (ePUCCH) refers to a PUCCH structure occupying an uplink B-I FDMA interlace and having a predefined transmission duration (such as 1 ms, i.e. 14 SC-FDMA symbols, or potentially 12 or 13 SC-FDMA symbols if the same subframe includes sounding reference signals and/or a gap for LBT operation). ePUCCH is multiplexed with PUSCH in the frequency domain. ePUCCH may be used primarily to carry group HARQ-ACK, i.e. HARQ-ACK for all downlink HARQ-processes for a given carrier or multiple carriers. Triggering for ePUCCH may be aperiodic triggering by eNB. Aperiodic triggering provides an opportunity for eNB to poll pending HARQ-ACKs. Alternatively, or in addition, ePUCCH can carry also Aperiodic CSI as in LTE (i.e. A-CSI transmission without simultaneous PUSCH data). The time duration of ePUCCH (for certain uplink control information (UCI)) may be 1 subframe. It may also be shorted e.g. by one SC-FDMA symbol from the beginning or from the end of the subframe. This may be needed e.g. in order to provide room for LBT in the middle of UL Tx burst (UL cycle). ePUCCH may support large UCI payload sizes with uncompromized UL coverage. Multiple users may be multiplexed on the same ePUCCH interlace. ePUCCH does not require a predefined time relation (other than 4 subframe minimum processing delay constraint) for HARQ-ACK with DL subframes where the DL grants are transmitted

There are three different basic schemes available for triggering ePUCCH. Triggering ePUCCH (or UCI transmission on PUSCH) via UL grant is one option. For UL grant triggering, ePUCCH resources are indicated in UL grant. There is coexistence with aperiodic CSI ; if there is a simultaneous UL data transmission, UCI is multiplexed with PUSCH. UL grant triggering is similar to LTE operation (e.g., uplink control information on PUSCH without UL-SCH data), requires a small standardization effort. UL grant triggering may provide fully flexible resource utilization and be robust against error cases. However, downlink control information (DCI) (i.e. physical downlink control channel (PDCCH)) overhead increases with the number of UEs. In some scenarios an UL grant based approach may involve excessive DCI overhead, especially in the case when PDSCH HARQ-ACK for multiple UEs are triggered at the same time. For that reason, common PDCCH may also be considered as an option.

Common PDCCH utilizes preconfigured ePUCCH resources. Triggering is based on a common DCI. There is limited flexibility in PUSCH resource utilization (which may lead to increased UL overhead). There may be additional complexity at eNB related to different error cases. One error case may be that a UE may not detect common trigger and will multiplex UCI with PUSCH data accordingly; eNB may need to monitor multiple containers (e.g.

PUSCH and ePUCCH) at the same time. Common PDCCH may involve a small DCI overhead, relative to UL grant triggering. DL grant utilizes preconfigured ePUCCH resources. There may be similarities with ARI- based resource selection in with LTE CA PUCCH. Limited flexibility in PUSCH resource utilization may lead to increased UL overhead. Increased DL grant size (ACK/NACK resource indicator (ARI), subframe index) may also lead to increased (or excessive) DCI overhead when triggering ePUCCH.

In LTE, the power control commands for PUSCH are conveyed in UL grant and for PUCCH in DL assignment, respectively. In addition to that, group power control commands for PUSCH and PUCCH can be transmitted on DL using the DCI formats 3/3A. DCI format 3/3A is used for the transmission of transmit power control (TPC) commands for PUCCH and PUSCH with multiple 1 -bit (Format 3) or 2-bit (Format 3A) power adjustments for a group of UEs. The target UE may receive a TPC command intended for it based on the parameter tpc-lndex provided by higher layers. The cyclic redundancy check (CRC) of the DCI format 3/3A is scrambled with TPC-PUCCH-RNTI (radio network temporary

identifier)/TPC-PUSCH-RNTI to separate PC commands for different UE groups. The payload for DCI format 3/3A @20 MHz bandwidth equals 28 bits. Hence, one grant can support power control (PC) command for at maximum 28 (DCI format 3) or 14 (DCI format

3 A) UEs

The principle of DCI format 3 is shown in Figure 5. The UE of interest has been configured to use TCP index #12. When it detects DCI scrambled with TPC-PUCCH-RNTI or TPC- PUSCH-RNTI, it will read the corresponding TPC command ("1 " in this example) from the corresponding TPC index.

Figure 6 shows a flowchart of an example method according to embodiments. In a first step, S1 , the method comprises receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices.

In a second step, S2, the method comprises determining whether to transmit uplink control information based on said downlink control information.

If so, the method comprises a third step, S3 of determining at least one control channel resource for transmission of uplink control information based on the downlink control information and a fourth step, S4 of causing transmission of uplink control information using the at least one determined control channel resource.

The at least one control channel may be ePUCCH.

Resource allocation may be defined based on ERI (ePUCCH Resource Index). The downlink control information (DCI) may comprise a plurality of indices (referred to as UE index). The first user, or each of the plurality of user devices, may be associated with a respective one of the plurality of indices. Each index may have an associated index value, e.g. an associated PUCCH resource index, or ERI. The index value may comprise an indication of whether to cause uplink control information transmission, i.e. a UCI trigger or no trigger, or reserve control channel resource. The index value may comprise an indication of the at least one control channel resource for transmission of the uplink control information. The index value, or ERI, may comprise two bits.

A method as described with reference to Figure 6 may provide triggering of ePUCCH (or UCI transmission in general) using common DCI. The DCI is defined for ePUCCH triggering. The DCI may be denoted as DCI format 3B. The DCI format 3B may utilize the same size as DCI format 3/3A. This will ensure that

(E)PDCCH blind detection burden at the UE end does not increase compared to operation without common ePUCCH triggering.

The DCI may be coded using the control channel radio network temporary identifier. For example, the CRC of the DCI format 3B may be scrambled with ePUCCH-RNTI. The user device may be preconfigured with at least one of the control channel radio network temporary identifier, the associated UE index and the at least one control channel resource for transmission of the UCI. For example, the UE may be configured via higher layers with the ePUCCH-RNTI, a UE index and/or the number of parallel resources with a predefined ERI.

When the UE receives DCI Format 3B scrambled with the configured ePUCCH-RNTI, the user device reads the ERI corresponding to the pre-configured UE index and operates accordingly. In the example shown in Figure 7, a UE will transmit ePUCCH at a predetermined time, and using the 1^st higher layer configured UL (ePUCCH) resource indicated by ERI value "01 ". The UCI may comprise at least one HARQ-ACK bit or process. For example, the ePUCCH may carry e.g. HARQ-ACK information for all HARQ processes. According to the example shown in Figure 7, 14 UEs per ePUCCH-RNTI may be supported when having a 2-bit ERI. Increasing the length of ERI field increases the number of parallel ePUCCH resources available for given UE, at the expense of multiplexing capacity. The 2-bit ERI allows for the eNodeB to trigger the UE to perform ePUCCH transmission on one of three alternative ePUCCH resources associated with the different ERI values as shown in Figure 7. A predetermined ERI value ('00' in the example shown in Figure 7) may indicate to the UE that ePUCCH is not triggered for given UE.

Minimizing PUSCH (UL) resource fragmentation due to ePUCCH may be desirable. This may be possible if eNB assigns consecutive resources for different UEs. On the other hand, the number of UEs that can be supported with a single DCI Format 3B should be maximized. In the following, we depict an embodiment for the ePUCCH triggering, which fulfils those criteria. In an embodiment such as that shown in Figure 8, ePUCCH triggering relates to predefined ePUCCH resources. At least one index value of the plurality of index values comprises an indication of at least one control channel resource for transmission of the uplink control information. A predefined indexing scheme may be applied among the available ePUCCH resources. Indexing may start from the lowest B-IFDMA interlace. Indexing may be arranged firstly within an interlace, and secondly between interlaces. Parallel resources within an interlace may be arranged by means of code division multiplexing (CDM) or IFDMA. Table 1 shows an example for indexing parallel ePUCCH resources available in certain subframe. It assumes that there are four parallel resources within each B-IFDMA interlace and they are created by means of orthogonal cover code.

Table 1

The starting resource index (or the starting interlace) is preconfigured via higher layer signalling. Another option is to start indexing always from the interlace with lowest index. When UE receives DCI scrambled with configured ePUCCH-RNTI, it will read the UE indexes. UE index value indicates UEs with ePUCCH transmission ("1 " indicates triggering, "0" indicates no triggering).

The method may comprise determining the at least one control channel resource for transmission of uplink control information The ePUCCH resource [0,1 , ...] for UE index N may be determined according to the following equation (see also Figure 8): starting resource index + (∑ ₌₀ UEjndex(k)) - 1. This equation applies to the scenario with one-bit index. The principle can be extended also to the case where UE index covers multiple bits. For example, in the case of two-bit triggering, code points "01 ", "10", "1 1 ", may reserve an ePUCCH resource whereas codepoint "00" may not reserve any ePUCCH resource.

In other words, each UE scheduled to transmit ePUCCH based on the current DCI takes into account other UEs triggered with the same DCI Format 3B in ePUCCH resource allocation.

In the example shown in Figure 8, the resource allocation for Nth UE (N=12) is considered. Teh starting resource index = 0. UE indexes [0 2 3 4 5 6 9 19 1 1 ] don't reserve any ePUCCH resources. UE indexes [1 2 8 12] reserve ePUCCH resources

UE with N=1 occupies the 1 ^st resource (resource index =0). UE with N=7 occupies the 2^nd resource . UE with N=8 occupies the 3^rd resource. UE with N=12 occupies the 4^th resource (resource index = 3). The method may comrpise causing transmission of the uplink control information a predetermined time after receiving the downlink control information. For example, the ePUCCH trigger may have a predetermined timing relationship between the DCI and ePUCCH transmission. The timing relationship may be fixed in the specification, e.g. such that ePUCCH corresponding to a trigger received in subframe n is transmitted in subframe n+4. Alternatively, or in addition, the DCI may comprise timing information for UCI transmission. For example, one option may be to reserve e.g. 1 -3 bits from the payload or DCI Format 3B to indicate the Tx time.

It is noted that the current solution supports up-to 28 UEs per DCI format 3B. Furthermore, it minimizes the PUCCH resource fragmentation since the allocated resources are continuous in determined resource space.

In an embodiment, as shown in Figure 9, the starting resource/interlace index may be given in the ePDCCH using predetermined bit field instead of preconfigured value.

This may provide full scalability, an eNB may allocate one or multiple DCI Format 3B in the same subframe.

A similar field may be defined for indicating the ePUCCH format (among plurality of available formats configured). This may provide dynamic format adaptation for ePUCCH. For example, one DCI Format 3B may trigger smaller ePUCCH formats, and another DCI Format 3B may trigger larger formats, respectively. ePUCCH format adaptation may be defined also based on separate ePUCCH-RNTIs configured. Each ePUCCH-RNTI may have a separate starting point configured. Based on those there can be multiple ePDCCH-RNTIs configured e.g., for different UE groups and/or for different ePUCCH formats

In an embodiment, more than one bit may be used for triggering as shown in Figure 7 where two bits are used. One code point, preferably "all zeros" would indicate "no triggering". This indicates that the corresponding UE does not occupy the channel. All UEs may have the same size for the triggering field, this may make applying resource allocating principles depicted in Figure 8 more straightforward. Other code points may indicate "triggering with different parameters" (for example CDM within resource). There may be separate bits for power control or other parameters.

Different ePUCCH-RNTI's may be defined for sPUCCH and ePUCCH. sPUCCH triggering may be related to periodic sPUCCH or sPUCCH located at the end of DL Tx burst. sPUCCH and ePUCCH may involve also usage of different PUCCH formats.

A method as described above may facilitate simultaneous triggering of UCI (especially HARQ-ACK) transmission for up to 28 UEs while keeping the DL control signal overhead at a low level. PUSCH resource fragmentation may be minimised. The presented solution is fully scalable in terms of number of ePUCCH formats. The proposed method is in line with current DCI principles/sizes so that no blind detection burden at UE may be introduced.

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 a standalone LTE networks, similar principles maybe applied in relation to other examples of standalone 3G, LTE or 5G networks. It should be noted that other embodiments may be based on other cellular technology other than LTE or on variants of LTE. 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 10. The method may be implanted in a single processor 201 or control apparatus or across more than one processor or control apparatus. Figure 10 shows an example of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, (e) node B, a central unit of a cloud architecture or a node of a core network such as an MME or S-GW, a scheduling entity, or a server or host. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. 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. Control functions may comprise receiving, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices, determining whether to transmit uplink control information based on said downlink control information and, if so, determining at least one control channel resource for transmission of uplink control information based on the downlink control information and causing transmission of uplink control information using the at least one determined control channel resource.

Alternatively, or in addition, control functions may comprise providing, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information and receiving transmission of uplink control information using the at least one determined control channel resource. 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 first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices;

determining whether to transmit uplink control information based on said downlink control information and, if so,

determining at least one control channel resource for transmission of uplink control information based on the downlink control information; and

causing transmission of uplink control information using the at least one determined control channel resource.

2. A method according to claim 1 , wherein the downlink control information comprises a plurality of indices, the first user device is associated with a respective one of the plurality of indices and each of the plurality of indices has an associated index value.

3. A method according to claim 2, wherein each index value comprises an indication of whether to cause uplink control information transmission or reserve control channel resource.

4. A method according to claim 2 or claim 3, wherein the index value associated with the respective one of the plurality of indices comprises an indication of the at least one control channel resource for transmission of the uplink control information.

5. A method according to claim 4, wherein the at least one control channel resource for transmission of the uplink control information is preconfigured at the first user device.

6. A method according to any one of claims 2 to 5, wherein the index value comprises two bits.

7. A method according to claim 2 or claim 3, wherein at least one index value comprises an indication of at least one control channel resource for transmission of the uplink control information.

8. A method according to claim 7, comprising determining the at least one control channel resource for transmission of uplink control information based on the index values associated with the other of the plurality of indices.

9. A method according to claim 7, wherein the at least one control channel resource is determined based on a starting resource index defined for the downlink control information.

10. A method according to any preceding claim, wherein the downlink control information is coded using the at least one control channel radio network temporary identifier.

1 1 . A method according to any preceding claim, wherein the uplink control information comprises at least one hybrid automatic repeat request acknowledgement.

12. A method according to any preceding claim, wherein the control channel is an enhanced physical uplink control channel.

13. A method according to any preceding claim, comprising causing transmission of the uplink control information a predetermined time after receiving the downlink control information.

14. A method according to any one of claims 1 to 12, wherein the downlink control information comprises timing information for uplink control information transmission.

15. A method comprising:

providing, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information; and

receiving transmission of uplink control information using the at least one determined control channel resource.

16. An apparatus comprising means for performing a method according to any one of claims 1 to 15.

17. A computer program product for a computer, comprising software code portions for performing the steps of any of claims 1 to 15 when the product is run on the computer.

18. An apparatus comprising:

at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

receive, at a first user device, downlink control information from a network node, said downlink control information associated with at least one control channel and common to a plurality of user devices;

determine whether to transmit uplink control information based on said downlink control information; and, if so,

determine at least one control channel resource for transmission of uplink control information based on the downlink control information; and

cause transmission of uplink control information using the at least one determined control channel resource.

19. An apparatus comprising:

provide, to a plurality of user devices, downlink control information from a network node, said downlink control information associated with at least one control channel and for use in determining whether to transmit uplink control information and, if so, at least one control channel resource for transmission of uplink control information; and

receive transmission of uplink control information using the at least one determined control channel resource.