Patent Description:
This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section. Abbreviations that may be found in the specification and/or the drawing figures are defined below, after the main part of the detailed description section.

There are several unlicensed bands having wide frequency bands. Even a single gNB or a UE can access very wide bandwidths using these. Hence, wideband operation is one of the building blocks for NR unlicensed band operation. In fact, 3GPP has approved a new study item (SI) related to NR-based access to unlicensed spectrum.

For such NR unlicensed (NR-U) band scenarios, there should be some way for the network (e.g., gNB) to get control information to the UE concerning the NR-U band. One way is using a downlink control channel, and specifically PDCCH transmissions and monitoring in the case when NR-U operates according to wideband operation. <CIT> discloses a mechanism for power saving in a wireless network, wherein a processor determines a processing state pertaining to behavior of the a wireless unit and determines a minimum amount of resources to be processed for one or more sets of physical resources based on the determined processing state. Each respective set of physical resources may comprise resources in time, and any of frequency or space. For each respective set of physical resources, the time may comprise a frame structure associated with a numerology applicable to the respective set of physical resources, the frequency may comprise any of a frequency location, a bandwidth, or the numerology, and the space may comprise one or more beams. <CIT> discloses a mechanism for a machine type communication (MTC) terminal to report a channel state information (CSI) in a wireless communication system, wherein the mechanism comprises the steps of: selecting a set of M downlink subframes as a CSI reference resource for the MTC terminal; measuring a channel quality indicator (CQI) through the CSI reference resource; and transmitting a CSI report including the CQI to a base station through an uplink subframe, wherein the MTC terminal is configured to repeatedly receive an MTC signal by frequency-hopping N sub-bands among a plurality of sub-bands. The number 'M' of the downlink subframes to be included in the CSI reference resource is determined on the basis of an upper layer parameter received from the base station.

The dependent claims describe advantageous optional embodiments. The scope of protection of the invention is solely limited by the appended claims.

The exemplary embodiments herein describe techniques for wideband PDCCH for the unlicensed band and suitable for new radio. Additional description of these techniques is presented after a system into which the exemplary embodiments may be used is described.

Turning to <FIG>, this figure shows a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced. In <FIG>, a user equipment (UE) <NUM> is in wireless communication with a wireless network <NUM>. A UE is a wireless, typically mobile device that can access a wireless network. The UE <NUM> includes one or more processors <NUM>, one or more memories <NUM>, and one or more transceivers <NUM> interconnected through one or more buses <NUM>. The one or more buses <NUM> may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The UE <NUM> includes a wideband (WB) physical downlink control channel (PDCCH) module <NUM>, comprising one of or both parts <NUM>-<NUM> and/or <NUM>-<NUM>, which may be implemented in a number of ways. The WB PDCCH module <NUM> may be implemented in hardware as WB PDCCH module <NUM>-<NUM>, such as being implemented as part of the one or more processors <NUM>. The WB PDCCH module <NUM>-<NUM> may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the WB PDCCH module <NUM> may be implemented as WB PDCCH module <NUM>-<NUM>, which is implemented as computer program code <NUM> and is executed by the one or more processors <NUM>. For instance, the one or more memories <NUM> and the computer program code <NUM> may be configured to, with the one or more processors <NUM>, cause the user equipment <NUM> to perform one or more of the operations as described herein. The UE <NUM> communicates with gNB <NUM> via a wireless link <NUM>.

The gNB <NUM> is a base station (e.g., for NR/<NUM>) that provides access by wireless devices such as the UE <NUM> to the wireless network <NUM>. Although primary reference herein is to a gNB, it might also be possible for disclosed techniques to be performed by an eNB, which is a base station for LTE. The gNB <NUM> includes one or more processors <NUM>, one or more memories <NUM>, one or more network interfaces (N/W I/F(s)) <NUM>, and one or more transceivers <NUM> interconnected through one or more buses <NUM>. The gNB <NUM> includes a WB PDCCH module <NUM>, comprising one of or both parts <NUM>-<NUM> and/or <NUM>-<NUM>, which may be implemented in a number of ways. The WB PDCCH module <NUM> may be implemented in hardware as WB PDCCH module <NUM>-<NUM>, such as being implemented as part of the one or more processors <NUM>. The WB PDCCH module <NUM>-<NUM> may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the WB PDCCH module <NUM> may be implemented as WB PDCCH module <NUM>-<NUM>, which is implemented as computer program code <NUM> and is executed by the one or more processors <NUM>. For instance, the one or more memories <NUM> and the computer program code <NUM> are configured to, with the one or more processors <NUM>, cause the gNB <NUM> to perform one or more of the operations as described herein. Two or more gNBs <NUM> communicate using, e.g., link <NUM>. The link <NUM> may be wired or wireless or both and may implement, e.g., an X2 interface.

The one or more buses <NUM> may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers <NUM> may be implemented as a remote radio head (RRH) <NUM>, with the other elements of the gNB <NUM> being physically in a different location from the RRH, and the one or more buses <NUM> could be implemented in part as fiber optic cable to connect the other elements of the gNB <NUM> to the RRH <NUM>.

It is noted that description herein indicates that "cells" perform functions, but it should be clear that the gNB that forms the cell will perform the functions. The cell makes up part of a gNB. That is, there can be multiple cells per gNB. For instance, there could be three cells for a single gNB carrier frequency and associated bandwidth, each cell covering one-third of a <NUM> degree area so that the single gNB's coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a gNB may use multiple carriers. So if there are three <NUM> degree cells per carrier and two carriers, then the gNB has a total of <NUM> cells.

The wireless network <NUM> may include a network control element (NCE) <NUM> that may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). The gNB <NUM> is coupled via a link <NUM> to the NCE <NUM>. The link <NUM> may be implemented as, e.g., an S1 interface. The NCE <NUM> includes one or more processors <NUM>, one or more memories <NUM>, and one or more network interfaces (N/W I/F(s)) <NUM>, interconnected through one or more buses <NUM>. The one or more memories <NUM> and the computer program code <NUM> are configured to, with the one or more processors <NUM>, cause the NCE <NUM> to perform one or more operations.

The computer readable memories <NUM>, <NUM>, and <NUM> 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, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories <NUM>, <NUM>, and <NUM> may be means for performing storage functions. The processors <NUM>, <NUM>, and <NUM> may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The processors <NUM>, <NUM>, and <NUM> may be means for performing functions, such as controlling the UE <NUM>, gNB <NUM>, and other functions as described herein.

Having thus introduced one suitable but non-limiting technical context for the practice of the exemplary embodiments of this invention, the exemplary embodiments will now be described with greater specificity.

As described above, 3GPP has approved a new study item related to NR-based access to unlicensed spectrum. This document concerns monitoring of the downlink control channel in NR unlicensed (NR-U) band scenarios. More specifically, we consider PDCCH monitoring in the case when NR-U operates according to wideband operation.

The rest of this disclosure is divided into sections for ease of reference.

NR physical downlink control channel (PDCCH) may be used to convey downlink control information (DCI). It may utilize OFDM waveform(s) and polar coding. NR PDCCH may utilize every fourth resource element for demodulation reference signals (DMRSs). DCI can be used for downlink (DL) and uplink (UL) resource allocation signaling. DCI may be used also for other purposes, such as carrier aggregation and bandwidth part (BWP) (de)activation, frame structure indication (with group common PDCCH, GC-PDCCH) and power control updates. GC-PDCCH may be used for slot format indication (SFI) in NR.

Certain embodiments herein are directed to the monitoring of the control channel in NR that may be carried out by means of blind searches. Blind searching, also called blind decoding, refers to the process by which a UE <NUM> finds its PDCCH by monitoring a set of PDCCH candidates in every monitoring occasion. A monitoring occasion can be once a slot, once per multiple slots, or multiple times in a slot. In an embodiment, physical downlink control channel (PDCCH) blind search may be arranged by means of parallel search space sets mapped to one or multiple control resource sets (CORESETs). During a PDCCH blind search, a UE <NUM> may be monitoring predefined control channel elements (CCEs), aggregated CCEs and/or downlink control information (DCI) sizes with predefined RNTIs (Radio Network Temporary Identifier) in predefined time instants, corresponding to configured monitoring occasions.

CCEs may be arranged within a predefined CORESET configured via higher layer signaling. Each CCE may include <NUM> REGs, each REG consisting of <NUM> subcarriers within <NUM> OFDM symbol, and <NUM>, <NUM> or <NUM> REG bundles. REG bundles may be arranged into the CORESET either according to interleaved or non-interleaved mapping. The UE <NUM> may assume that REG bundle defines the precoder granularity in frequency and time used by the gNB <NUM> when transmitting PDCCH. CORESET resources may be configured in units of <NUM> resource blocks in the frequency. <FIG>, split over <FIG> and <FIG>, illustrates an example PDCCH mapping assuming <NUM> symbol CORESET, interleaved REG-to-CCE mapping and REG bundle size <NUM>. A <NUM>-RB (resource block) grid is shown. The numbers below the blocks indicate the CCEs being used, where each of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> corresponds respectively to CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, and CCE #<NUM>. Table <NUM> below lists the REG bundle sizes options in terms of REGs, supported by new radio (NR):.

There is a linkage between a search space set and a CORESET. In Rel-<NUM>, the max number of CORESETs configurable for a bandwidth part (BWP) in a cell for a UE is three and the max number of search space sets configurable for a BWP in a cell for a UE is <NUM>, respectively.

As previously stated, wideband operation is one of the building blocks for NR unlicensed. Both carrier aggregation and BWP (bandwidth part) mechanisms are supported in Rel-<NUM> NR for wideband operations (on licensed spectrum) and NR unlicensed may use both mechanisms to achieve sufficiently versatile support for wideband.

Conventional carrier aggregation offers several benefits, such as the following:.

Hence, carrier aggregation may be supported for NR unlicensed in addition to facilitating the LAA operation with NR licensed carrier. Of course, carrier aggregation has also its price: multiple RF chains are required, increasing the price of UE transceivers. Additionally, carrier aggregation increases UE power consumption and has rather considerable latency in the component carrier activation/deactivation (to save UE power).

In Rel-<NUM> NR, a concept of serving cell adaptive BW was introduced by means of BWPs. In Rel-<NUM> NR, a UE is instructed to operate on a specific part of a gNB's BW, that is, on a BWP. Up to four BWPs can be configured separately for UL and DL. Each BWP can have, e.g., the following, separately configured:.

In case of unpaired spectrum (i.e. TDD), UL and DL BWPs can be paired, in which case the center frequency of both BWPs is required to be the same. One of the BWPs may be defined as the default BWP.

In Rel-<NUM> NR, a UE <NUM> may have only one BWP active at a time. The active BWP can be indicated by a field in the DCI or by RRC signaling. BWP switching occurs after UE has received the signaling changing the active BWP, but switching time is yet to be determined. The UE may also fall back to default BWP after a configured period of inactivity.

The BWP mechanism provides an alternative wideband mechanism when accessing unlicensed spectrum on adjacent <NUM> channels, as this mechanism can provide savings in UE cost with reduced number of RF chains. A single RF chain and FFT processing can be used to access wide bandwidth of, e.g., <NUM> or <NUM> on <NUM> or <NUM> (potential) unlicensed bands. It is assumed herein that unlicensed band carrier size is, e.g., <NUM> or <NUM> (depending on the FFT size). Furthermore, if larger BW is needed, then there will be multiple carriers. This mechanism also improves the trade-off between UE throughput and battery consumption via fast dynamic BWP switching. As the BWP switching time is shorter than the component carrier (de)activation time (subject of current discussion in RAN4), the UE can be switched rather aggressively to narrow BWP (and back to wideband BWP), saving UE battery and compromising throughput less than the slower CC (de)activation. On the other hand, NR BWP switching time (about hundreds of microseconds) has clearly a different order of magnitude than a single clear channel assessment (CCA) (e.g., <NUM> microseconds) in an LBT procedure, where CCA is equivalent to a single measurement within an LBT procedure. This poses significant constraints on how BWP operation and LBT can interact.

Channel contention (i.e., LBT) mechanism is one of the components for efficient wideband operation, and the channel contention mechanism for wideband operations needs to be considered during the NR-Unlicensed study item (SI). It should be noted that both Wi-Fi and LTE LAA LBT operate on <NUM> channels and some of the regulatory rules, e.g. ETSI's standard, require LBT operation on a <NUM> grid at <NUM> unlicensed bands. Hence, to meet regulatory requirements and to ensure fair coexistence with other systems, also NR unlicensed bands should support at least a <NUM> grid for LBT operation. Of course, also wider LBT BWs should be supported for higher frequency unlicensed bands or for potential new unlicensed bands like the <NUM> band.

For NR-unlicensed wideband (larger than <NUM>) carrier we assume the following scenario, in an exemplary embodiment:.

For the purpose of this document, we define the following terminology.

Carrier bandwidth is the NR carrier bandwidth, such as a carrier of <NUM> (two subbands of <NUM> each) for a subcarrier spacing of <NUM>, a carrier of <NUM> (four subbands of <NUM> each) for a subcarrier spacing of <NUM>, or a carrier of <NUM> (eight subbands, from zero to seven, of <NUM> each) for a subcarrier spacing of <NUM>. As can be seen for this example that assumes a <NUM> FFT, each carrier bandwidth comprises multiple <NUM> subbands.

A subband is one (or possibly multiple adjacent) channel(s) on an unlicensed carrier, typically having a bandwidth of <NUM>. A subband is aligned with the bandwidth of single LBT.

In an example, we consider a DL scenario. When operating according to NR-U scenario, a gNB <NUM> should perform LBT before the gNB <NUM> can start transmitting a DL NR-U Tx burst in the cell. To meet regulatory requirements and to ensure fair coexistence with other systems, also NR unlicensed should support subband LBT, e.g., with <NUM> resolution. The practical implementation of subband LBT is beyond the scope of this invention report. However, <FIG> shows possible transmission bandwidth for NR-U transmission combinations for a gNB <NUM> after a subband-specific LBT. This example assumes <NUM> carrier bandwidth, and contiguous allocation of <NUM> subbands. The subbands are <NUM>, <NUM>, <NUM>, and <NUM>, and the figure shows how one, two, three, or all four subbands could be allocated for NR-U transmissions.

Due to the subband specific LBT, prior to transmitting on the subbands that are available, the gNB <NUM> may need to adjust the transmission bandwidth (Tx BW) configuration, including RF settings (e.g., center frequency, analog filters) in order to meet the regulatory rules defined for the out-of-band emissions. The gNB <NUM> may decide on and perform the transmission bandwidth adaptation during the LBT process, although the details of gNB BW adaptation are outside of the scope of this description. However, for the purpose of this document, we define transmission bandwidth (TX BW) as a specific term. With this, we mean the part of the spectrum on which gNB actually transmits after LBT. As said, the TX BW may be equal to the carrier BW or the TX BW is a portion of carrier BW (one or more subbands) based on the outcome of LBT. It should be understood that given the said meaning of TX BW, change in Tx BW (e.g., and its configuration) may change the bandwidth of transmission, the center frequency of transmission, or both the bandwidth and center frequency of transmission.

From a UE point of view, the situation is more challenging. This can be seen as a chicken-and-egg problem, as follows:.

Hence, one exemplary problem is how to facilitate DL control channel monitoring when a UE <NUM> has uncertainty related to the gNB's Tx BW configuration. Consider the following questions. How can it be ensured that sufficient control channel capacity can be achieved also when the gNB Tx band is narrow? How can it be ensured that a UE's PDCCH blind decoding burden stays reasonable? How can it be ensured that there are sufficient numbers of BDs available for UE-specific DCIs? These are issues with these wideband NR-U scenarios currently having no clear answers.

Concerning other technologies, in an NR licensed band scenario, transmission bandwidth of the gNB is always known by the UE beforehand. In an LTE LAA scenario, this scenario supports WB operation only by means of carrier aggregation, where each carrier typically has its own, independent PDCCH. In a WiFi scenario, WiFi does not support scheduling structure based on PDCCH. Therefore, techniques used in these technologies do not transfer explicitly to wideband NR-U scenarios.

Exemplary embodiments herein solve or ameliorate the issues described above. Exemplary ideas relate to PDCCH monitoring in WB operation. Exemplary embodiments contain the following configuration aspects, depending on implementation:.

For each (DL) COT, the gNB <NUM> determines the RF configuration, in terms of consecutive (i.e., adjacent in frequency domain) subbands. This may be performed based on subband specific LBT. The gNB <NUM> may adjust its Tx BW configuration accordingly. According to an exemplary proposed idea, the gNB <NUM> indicates its Tx BW configuration to the UEs in the cell (e.g., at least) by means of DL control information. The "at least" is used here because this does not exclude usage of other signals such as preamble and/or PDCCH demodulation reference signal (DMRS) and/or tracking reference signal (TRS). The indication is conveyed via group common PDCCH (GC-PDCCH) and/or via dedicated DCI (such as DL/UL grant). Additionally, the Tx BW configuration may indicate the active subbands, e.g. in terms of bitmap or RIV (resource indication value). In addition to Tx BW configuration, the GC-PDCCH may indicate the slot format for one or more slots of the COT.

One important exemplary idea relates to the way the UE PDCCH monitoring and the corresponding CORESET(s) are arranged within the COT: (<NUM>) before knowing the gNB Tx BW configuration; and (<NUM>) after knowing the gNB Tx BW configuration.

In the following, we consider those aspects in more detail.

A number of exemplary aspects are described now.

A first aspect concerns determining the gNB Tx BW configuration from PDCCH. To be precise, this gNB Tx BW configuration is the intersection of UE BWP configuration and gNB Tx BW configuration. This is achieved such that the PDCCH candidates are confined within each subband. Furthermore, the configuration is made such that each subband contains sufficient amount of PDCCH candidates to convey PDCCH reliably enough. An example of the wideband CORESET configuration placed on a common PRB grid and covering four subbands is shown in the example of <FIG> illustrates CORESET spanning over four frequency chunks. Subcarrier spacing is <NUM> in this example. As can be seen, an <NUM> frequency band for a carrier is formed using <NUM> PRBs (=<NUM> / <NUM>) at <NUM> SCS, which is a common PRB raster. A <NUM> frequency band is formed using <NUM> PRBs at <NUM> SCS, of which <NUM> PRBs are used, e.g., for subband-specific CORESET. The other PRBs may be unused (e.g., to serve as guard bands). <FIG> also illustrates a size of two PRBs ("<NUM> PRBs").

In an exemplary embodiment, interleaving (if used) is performed within each subband but not between subbands (see also examples below). Additionally, the gNB <NUM> transmits (at least) one GC-PDCCH via (at least) one of the subbands, as indicated below:.

A second aspect concerns providing opportunities for additional control resources for the cases when only a limited number of subbands is active and included to the gNB's Tx BW. The motivation behind this is that one, e.g., GC-PDCCH, DL assignment, or UL grant DCI may require a considerable amount of control channel resources, e.g., up-to <NUM> CCEs, and this may consume the entire control channel capacity of a single subband. On the other hand, in cases when multiple subbands are available additional control channel capacity may not be needed. This is due to the fact that control channel capacity scales linearly with the channel bandwidth and a single GC-PDCCH may be shared between multiple subbands.

In this aspect, the additional control resources can be determined based on the DCI. Another option is to have the additional control resources present always when Tx BW configuration indicated by the gNB is just one or two subbands. Furthermore, the additional control resources may be available only for the first mini-slot or slot monitoring occasion of the COT, or in all mini-slots or slot monitoring occasions of the COT. The additional control resources may be available only on the subband carrying GC-PDCCH in the later slots of the COT.

A third aspect involves the UE changing the PDCCH monitoring based on detected indication on the gNB Tx BW configuration. In this aspect, PDCCH monitoring corresponding to the first mini-slot or slot covers all the possible subbands. When the gNB's Tx BW configuration is known after the first mini-slot or slot, the UE <NUM> adapts the PDCCH monitoring configuration (including also CORESET configuration, if changed) according to the determined Tx BW configuration. As discussed, the gNB <NUM> may dynamically allocate additional control resources already for the 1st slot of the COT. The change of the PDCCH monitoring may impact also on the PDCCH monitoring between different DCIs (i.e., search space set configuration). For example, the first slot may have more BDs for the GC-PDCCH whereas other slots may have more BDs for dedicated DCIs.

In the following, we provide three examples how the CORESET might be varied at the UE. In <FIG>, the first row <NUM> represents the CORESET monitoring based on the UE's BWP configuration, and the second row <NUM> represents the CORESETs based on the gNB's Tx BW configuration.

A first example concerns a case where an LBT procedure indicates for all subbands to be available for transmission, that is, they are unoccupied. This is illustrated in <FIG>, which illustrates a CORESET variation in response to LBT positive (meaning an LBT procedure indicates the channel can be used) for all subbands, using the <NUM> carrier of <FIG>. This is the assumed configuration:.

Subbands <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> are available for conveying other PDCCHs.

<FIG> in reference <NUM> shows the CCEs that are mapped to the REG bundles, where numbers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> indicate CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, and CCE #<NUM>, respectively. Note that this is merely for ease of reference, and other mappings may be used. Furthermore, one box corresponds to two REGs, and each CCE contains three REG bundles.

This example concerns LBT positive only for the second (2nd) subband. See <FIG>, which illustrates a CORESET variation in response to LBT positive only for the second subband <NUM>-<NUM>, using the <NUM> carrier of <FIG>. In this example, the Tx BW configuration covers only the 2nd subband <NUM>-<NUM>. An additional CORESET <NUM> is made available for another symbol (in this example, Symbol <NUM>) of the (mini-)slot for conveying other PDCCHs. Another symbol, illustrated as Symbol <NUM>, contains the GC-PDCCH, with aggregation level (AL) <NUM>, REG size of two and interleaved mapping. Symbols <NUM> and <NUM> are the first two OFDM symbols of a DL burst. This figure uses the same CCEs to REG bundles mapping in reference <NUM> from <FIG>.

In this example, LBT positive occurs for the second and third subband. See <FIG>, which illustrates a CORESET variation in response to LBT positive for the second (2nd) and the third (3rd) subband, using the <NUM> carrier of <FIG>. The Tx BW configuration covers the 2nd and the 3rd subbands. The GC-PDCCH is sent using the 2nd subband and using aggregation level <NUM>. There are <NUM> CCEs from the 2nd subband <NUM>-<NUM>, and <NUM> CCEs from the 3rd subband <NUM>-<NUM> that are available for conveying other PDCCHs. <FIG> in reference <NUM> shows the CCEs that are mapped to the REG bundles, where numbers <NUM>, <NUM>, <NUM>, and <NUM> indicate CCE #<NUM>, CCE #<NUM>, CCE #<NUM>, and CCE #<NUM>, respectively.

The following is an example for PDCCH monitoring burden. The following assumptions are made:.

It can be noted that this is a reasonable value (at least for the first slot of the COT). It has been agreed, for instance, that with <NUM> SCS, the UE supports <NUM> BDs per slot. Hence, based on this example, there would be <NUM> BDs/slot available for other BD candidates.

Possible exemplary UE operation is described in reference to <FIG> and <FIG>. <FIG> illustrates UE operation in four subbands <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> of NR-U WB bands according to an exemplary embodiment. <FIG> corresponds to <FIG>, where the second and third subbands <NUM>-<NUM> and <NUM>-<NUM> are LBT positive, meaning that an LBT process indicates the gNB <NUM> can transmit in those subbands. The time axis is divided into Steps <NUM>, <NUM>, and <NUM>, also described in <FIG>, each of which has symbols <NUM> and <NUM>, which are again the first two OFDM symbols of a DL burst. Note that all steps involve the same two symbols, i.e. the steps are following each other very rapidly in time.

<FIG> is split over <FIG> and <FIG>, and is a logic flow diagram performed by a UE for wideband PDCCH for the unlicensed band and suitable for new radio, and illustrates the operation of an exemplary method or methods, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments. The UE <NUM> is assumed to perform the blocks in <FIG>, e.g., under control at least in part by the WB PDCCH module <NUM>.

In block <NUM>, also referred to as Step <NUM>, the UE <NUM> performs PDCCH monitoring according to a first CORESET and at least one first search space set configuration on, e.g., n subbands (n=<NUM> in the example of <FIG>). That is, the UE <NUM> assumes it has to monitor all four subbands <NUM>-<NUM> through <NUM>-<NUM> and initially proceeds based on that assumption. In more detail, for symbol <NUM>, the initial assumption for the UE <NUM> and gNB <NUM> is that all subbands are used, and there are PDCCH CORESET portions on each of them. In Step <NUM> of <FIG>, the available control resources for the gNB <NUM> are shown, and Step <NUM> (described below) shows an actual transmission. With regard to search space set configuration, search space covers only one aggregation level. Search space set covers multiple aggregation levels, and PDCCH monitoring is configured per search space set.

Blocks <NUM> and <NUM> are possible examples corresponding to block <NUM>, and individual ones or both of these may be used. As indicated in block <NUM>, the value of n may depend, e.g., on the UEs BWP configuration, and is equal to or less than the maximum number of subbands that the gNodeB can transmit on the unlicensed band carrier. Note that if UE supports also carrier aggregation, this can be seen as operation performed separately for each component carrier. As indicated in block <NUM>, the at least one first search space set configuration may define the PDCCH monitoring (at least) for group common control information such as GC-PDCCH. This may indicate, e.g., a number of BD candidates and/or aggregation levels for GC information (e.g., GC-PDCCH) on each subband. Alternatively or in addition, it may also indicate the monitoring occasions (at least) for GC information (e.g., GC-PDCCH). It should also be noted that GC control information may be GC-PDCCH, but also may be referred to using other terminology, such as group common downlink control information. It is possible for the subbands of the second control resource set to be next to each other, e.g., as shown in <FIG>, where the subbands <NUM>-<NUM> and <NUM>-<NUM> are next to each other.

As can be seen in <FIG>, there is no PDCCH transmission in subbands <NUM>-<NUM> and <NUM>-<NUM>, as the channel is not available for use by the gNB <NUM> in these subbands. That is, the gNB <NUM> LBT fails (e.g., the channel is busy) and the gNodeB is not allowed to transmit using the unlicensed band in these two subbands. There are, however, available gNB NR-U WB transmissions in subbands <NUM>-<NUM> and <NUM>-<NUM>, and these occur because LBT is positive, meaning the LBT succeeded and the gNB <NUM> can transmit on the unlicensed band. As indicated above, Step <NUM> shows the available control resources for the gNB, and Step <NUM> shows an actual transmission of GC-PDCCH.

In block <NUM>, it is determined by the UE whether one or more PDCCHs have been detected. If not (block <NUM> = No), the flow proceeds to block <NUM>. If so (block <NUM> = Yes), flow proceeds to block <NUM>. Note that PDCCH monitoring relates to predefined DCI formats with predefined RNTIs. Put differently, the UE detects control information intended to the UE on the PDCCH resources, and if there is such information, there is a detection of PDCCH in block <NUM> (and similarly in block <NUM>, described below). Since there is a PDCCH transmission in subband <NUM>-<NUM> (see Step <NUM> in <FIG> and the transmission in symbol <NUM>), the flow proceeds to block <NUM>.

In block <NUM>, also referred to as Step <NUM>, based on the PDCCH monitoring and in response to at least one PDCCH being detected (e.g., CRC positive), the UE determines the gNodeB's Tx BW configuration. That is, the UE determines the subbands that the gNodeB uses for transmission during a given COT. However, because of LBT failures, some of the subbands <NUM> cannot be used. The eNB <NUM> indicates that to the UE <NUM> via GC-PDCCH, in this example in symbol <NUM> of Step <NUM>, the first CORESET configuration being confined on the first symbol of the (mini-)slot. The gNodeB <NUM> takes also symbol #<NUM> into use in Step <NUM> for PDCCH CORESETs (to compensate for the subbands <NUM> and <NUM> that cannot be used due to failed LBT in those subbands). The UE initially attempts to receive PDCCH from all subbands in symbol <NUM> and discovers GC-PDCCH in subband <NUM>-<NUM>. The GC-PDCCH in symbol <NUM> of the second subband <NUM>-<NUM> tells the UE that there are also additional CORESETs that the UE should monitor within symbol #<NUM> (see Step <NUM>). The Tx BW configuration covers the second and the third subbands <NUM>-<NUM> and <NUM>-<NUM>, respectively, in the example of <FIG>. Blocks <NUM> and <NUM> are options corresponding to block <NUM>. As indicated by block <NUM>, the determination may be performed based on indication(s) carried on GC-PDCCH, which is illustrated in symbol <NUM> and subband <NUM>-<NUM> of Step <NUM> in <FIG>. Alternatively and/or complementary, as indicated in block <NUM>, the determination may be carried on dedicated DCI (such as a DL grant). This approach may be used, e.g., for UEs configured to narrowband operation.

In block <NUM>, also referred to as step <NUM>, after determining the gNodeB's Tx BW configuration, the UE continues PDCCH monitoring, using the determined gNodeB's Tx BW configuration, e.g., according to a second CORESET configuration and at least one second search space set on m subbands, m≤n. In this example, n=<NUM> and m=<NUM>, but this is merely exemplary. This second CORESET configuration indicates in this example that symbol <NUM> in subbands <NUM>-<NUM> and <NUM>-<NUM> contains CORESET and should be monitored. That is, the UE may assume CORESET/search space set configuration according to Step <NUM> for all PDCCH at least until the end of the COT. In other words, Step <NUM>, Step <NUM> are carried out only when there is uncertainty with respect to TX BW of the gNB <NUM>.

It should be noted that Step <NUM> and Step <NUM> may alternatively be considered to be logical steps, which means that it is possible to run them also in parallel. Consider the following options. Option <NUM>: Step <NUM> and Step <NUM> are carried out for a first monitoring occasion. Step <NUM> is carried out for a second monitoring occasion. Option <NUM>: Step <NUM> is carried out already for the first monitoring occasion.

Blocks <NUM>, <NUM>, <NUM>, and <NUM> are options corresponding to block <NUM>. As indicated in block <NUM>, the second CORESET may be a subset of the first CORESET, and is located on at least some of the active subbands (i.e., the m subbands) according to the gNodeB's Tx BW configuration. CCE indexing of the second CORESET may also depend on the gNodeB's Tx BW configuration.

As indicated in block <NUM>, the second CORESET may include also control resources on additional symbol(s) (when compared to the first CORESET). This may be determined based on GC-PDCCH received according to the first CORESET and at least one first search space set configuration. In block <NUM>, it is indicated that the second CORESET contains one or more portions in frequency (i.e., m subbands) and one or two portions in time (symbols occupied by the first CORESET + additional symbols if configured). In block <NUM>, it is indicated that the at least one second search space configuration contains PDCCH monitoring for at least one UE-specific DCI. The configuration may also contain a new search space set configuration for GC-PDCCH.

In block <NUM>, it is determined whether one or more PDCCHs have been detected. If not (block <NUM> = No), the flow proceeds to block <NUM>. If one or more PDCCHs have been detected (block <NUM> = Yes), the UE <NUM> determines in block <NUM> whether control information is in the PDCCH and, if so, uses the control information to receive data from gNodeB's NR-U Tx BW or to transmit data to the gNB <NUM> (or both), using the NR-U Tx BW. It is noted that for an UL transmission from the UE <NUM> to the gNB <NUM>, from the gNB point of view, this would be performed over NR-U Rx BW. On the other hand, as this is a TDD system, gNB's Tx BW and Rx BW are fully aligned. Therefore the NR-U Tx BW terminology is maintained here.

It should be noted that operation does not require that UE switches its BWP (including RF) to correspond to the (intersection of UE BWP and) gNB Tx BW. Instead, the UE <NUM> may keep its current BWP and corresponding RF BW. This is an important difference to Rel-<NUM> BWP switching. One benefit of this is that there is no BWP switch transition time which may be in range of <NUM> - <NUM>, i.e., in the order of few slots. As a possible downside, there can be increased impact from interference originating from other radio systems via inactive subbands.

The related gNB/network operation is basically given by the direct counterpart to <FIG>. Referring to <FIG>, this figure is a logic flow diagram performed by a gNB for wideband PDCCH for the unlicensed band and suitable for new radio. <FIG> is split over <FIG> and <FIG>. This figure illustrates the operation of an exemplary method or methods, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments. The blocks in <FIG> are assumed to be performed by a base station such as gNB <NUM>, e.g., under control of the WB PDCCH module <NUM> at least in part. The gNB <NUM> is assumed, though other base stations (such as an eNB) or network nodes may be used.

In block <NUM>, the gNB <NUM> configures the UE <NUM>, e.g., with BWP configuration and the at least one first search space set configuration. In block <NUM>, the gNB <NUM> performs an LBT process on all (e.g., n) subbands to determine actual TX BW configuration for the unlicensed band carrier. This corresponds in part to Step <NUM> of <FIG>. In block <NUM>, the gNB <NUM> transmits at least one PDCCH via CORESET/search space set configuration defined according to actual TX BW configuration. The at least one PDCCH indicates to the UE the actual TX BW configuration for the unlicensed band carrier. This corresponds to Step <NUM> of <FIG>. Blocks <NUM> and <NUM> are examples of possible implementations of block <NUM>. As block <NUM> indicates, the indication(s) may be carried on GC-PDCCH. Alternatively or additionally, as per block <NUM>, the indication(s) may be carried on dedicated DCI (such as a DL grant).

In block <NUM>, transmits at least one PDCCH, using actual Tx BW configuration, according to a second CORESET and at least one second search space set configuration on m subbands defined by the actual Tx BW configuration. Block <NUM> corresponds to Step <NUM> in <FIG>. Blocks <NUM>, <NUM>, <NUM>, and <NUM> are examples of possible implementations associated with block <NUM>. As indicated in block <NUM>, the second CORESET may be a subset of the first CORESET and is located on at least some of the active subbands according to the actual Tx BW configuration. CCE indexing of the second CORESET may also depend on the actual Tx BW configuration. Block <NUM> indicates the second CORESET may include also control resources on additional symbol(s) (when compared to the 1st CORESET). This may be determined based on the transmitted GC-PDCCH according to the first CORESET and at least one first search space set configuration. Block <NUM> indicates the second CORESET contains one or more portions in frequency (i.e. m subbands) and one or two portions in time (symbols occupied by the first CORESET + additional symbols if configured). As indicated by block <NUM>, the at least one second search space contains PDCCH monitoring for at least one UE-specific DCI. The configuration may also contain a new search space set configuration for GC-PDCCH.

The gNB <NUM> in block <NUM>, in response to control information being in PDCCH for this UE, uses the control information to transmit data on (or receive data using) gNodeB's NR-U Tx BW for this UE. Note that the gNB <NUM> would put the control information into the PDCCH in block <NUM>.

Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect and advantage of one or more of the example embodiments disclosed herein is a reasonable UE blind detection burden. Another technical effect and advantage of one or more of the example embodiments disclosed herein is more robust operation, e.g., compared to preamble-only based solutions (due to CRC protection). For instance, all UEs become aware of the gNB's Tx BW configuration already at the beginning of the COT. Another technical effect and advantage of one or more of the example embodiments disclosed herein is these solutions provide scalable control channel capacity for different scenarios with different amount of subbands obtained. Another technical effect and advantage of one or more of the example embodiments disclosed herein is the solutions can provide sufficient control channel capacity also in the scenarios where gNB's Tx BW convers only one or two subbands.

Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in <FIG>. A computer-readable medium may comprise a computer-readable storage medium (e.g., memories <NUM>, <NUM>, <NUM> or other device) that may be any media or means that can contain, store, and/or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals.

It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claim 1:
A method, comprising:
performing (<NUM>), at a user equipment (<NUM>), first control channel monitoring according to a first control resource set and at least one first search space set configuration, the first control channel monitoring performed on n subbands, n><NUM>, able to be transmitted by a base station (<NUM>) in an unlicensed band carrier;
determining (<NUM>), in response to a detection of a control channel in the first control channel monitoring and from the control channel, a transmission bandwidth configuration to be used by the base station (<NUM>) in the unlicensed band carrier for control channels, wherein the determining the transmission bandwidth configuration to be used by the base station (<NUM>) in the unlicensed band carrier for control channels is performed based on one or more indications carried in the control channel on a group common physical downlink control channel and/or one or more indications carried in the control channel on dedicated downlink control information; and
performing (<NUM>), by the user equipment (<NUM>), second control channel monitoring according to a second control resource set and at least one second search space set configuration, the second control channel monitoring performed on m subbands, m≤n, in the unlicensed band carrier, the m subbands being a subset of the n of subbands, wherein the second control resource set is a subset of the first control resource set and is located on at least some of a plurality of the m subbands according to the determined transmission bandwidth configuration to be used by the base station (<NUM>) in the unlicensed band carrier for control channels.