WO2021074120A1

WO2021074120A1 - Initial access for frame based equipment

Info

Publication number: WO2021074120A1
Application number: PCT/EP2020/078721
Authority: WO
Inventors: Karol Schober; Esa Tapani Tiirola
Original assignee: Nokia Technologies Oy
Priority date: 2019-10-15
Filing date: 2020-10-13
Publication date: 2021-04-22

Abstract

In some example embodiment, there may be provided a method. The may include configuring, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and transmitting a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment. Related systems, methods, and articles of manufacture are also disclosed.

Description

INITIAL ACCESS FOR FRAME BASED EQUIPMENT

Field

[0001] The subject matter described herein relates to unlicensed spectrum usage.

Background

[0002] The 5G system may include support for unlicensed spectrum operation. This unlicensed operation is often referred to as NR-U (new radio-unlicensed). With NR-U, the 5G system may utilize unlicensed spectrum for carrier aggregation (e.g., within a given base station), dual connectivity (e.g., across two base stations or cells), standalone operation in the unlicensed spectrum, and/or the like.

[0003] Different regions have different regulatory requirements for unlicensed band operation. For example, 3 GPP TDoc RP- 140054 (“Review of Regulatory Requirements for Unlicensed Spectrum”) summarizes some of these different regulatory requirements for unlicensed band operation. In Europe for example, regulations mandate the equipment operating on unlicensed spectrum to implement listen before talk (LBT) performing a clear channel assessment (CCA) before starting a transmission to verify that the operating channel is not occupied. ETSI document EN 301 893 defines European regulatory requirements for the unlicensed band on 5 GHz band. ETSI defines two of modes of operation, namely frame based equipment (FBE) and load based equipment (LBE). With frame based equipment, the transmit and/or receive operate with fixed timing. Moreover, ETSI EN 301 893 requires that LBT and CCA be performed periodically at predefined time instances according to a predetermined frame structure. Unlike frame based equipment, load based equipment are not required to perform LBT and CCA according to a frame structure, but load based equipment may perform

LBT and CCA whenever it has data to transmit. Summary

[0004] In some example embodiment, there may be provided a method. The method may include configuring, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and transmitting a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

[0005] In some variations, one or more of the features disclosed herein including the following features can optionally be included in any feasible combination. The method may further include receiving a random access channel message during a random access channel occasion within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum. The subset may include one or more monitoring occasions, one or more physical downlink control channel candidates, a control resource set, a downlink control information payload, and a radio network temporary identifier. The group common physical downlink control channel monitoring may be within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum. The group common physical downlink control channel monitoring may include monitoring a group common physical downlink control channel candidate. The group common physical downlink control channel candidate may include configuration information common between the idle user equipment and the radio resource control connected user equipment. The group common physical downlink control channel candidate may include configuration information that is different between the idle user equipment and the radio resource control connected user equipment. The group common physical downlink control channel candidate may be specified by a standard and/or provided by the system information block including a remaining minimum system information block. The configuration information that is common may include a control resource set, a downlink control information payload, and a radio network temporary identifier. The group common physical downlink control channel may be transmitted during a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum. The channel occupancy time may include a random access channel occasion. The random access channel occasion may be within the channel occupancy time. The transmitted group common physical downlink control channel may be transmitted to the idle user equipment. The transmitted group common physical downlink control channel may include a downlink control information payload that indicates an end to a channel occupancy time of a fixed frame period and/or that indicates whether an associated physical random access channel resource is part of the channel occupancy time acquired by a base station.

[0006] In some example embodiment, there may be provided a method. The method may include receiving, via a system information block, a configuration to enable monitoring of a group common physical downlink control channel, the system information block including at least a radio network temporary identifier, a downlink payload size, and a search-space configuration that defines monitoring occasions for one or more group common physical downlink control channel candidates; determining a random access channel occasion for transmission; determining a group common physical downlink control channel monitoring candidate preceding the random access channel occasion; determining, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble; and transmitting, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.

[0007] In some variations, one or more of the features disclosed herein including the following features can optionally be included in any feasible combination. When the channel occupancy time is not available during the physical random access channel preamble, the method may further include determining another random access channel occasion for transmission. The determination of whether the channel occupancy time is available during a physical random access channel preamble may be further based on fixed frame period timing configured by a remaining minimum system information. When channel occupancy time is available during the physical random access channel occasion, the method may further include transmitting a random access channel preamble during the random access channel occasion for transmission. The method may further include determining availability based on the group common physical downlink control channel received in a fixed frame period including the random access channel occasion; and discarding at least a portion of a payload of the received group common physical downlink control channel. The method may further include determining availability based on the group common physical downlink control channel indicating an end time for the channel occupancy time, wherein the end time is a time that is the same or later than the random access channel occasion. The method may further include determining the channel occupancy time based on a system information block comprising a remaining minimum system information. When the apparatus is in idle mode, the method may further include determining whether the physical random access channel opportunity is within the channel occupancy time being acquired by a base station.

[0008] The above-noted aspects and features may be implemented in systems, apparatus, methods, and/or articles depending on the desired configuration. The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. Description of Drawings

[0009] In the drawings,

[0010] FIG. 1 depicts an example structure for a listen before talk framework including fixed frame periods, in accordance with some example embodiments;

[0011] FIG. 2 depicts an example of a fixed frame period, in accordance with some example embodiments;

[0012] FIG. 3 depicts a signaling diagram for a two-step random access channel (RACH) procedure, in accordance with some example embodiments;

[0013] FIG. 4A depicts an example of downlink control information (DCI), in accordance with some example embodiments;

[0014] FIG. 4B depicts an example of physical downlink control channel (PDCCH) candidates, in accordance with some example embodiments;

[0015] FIG. 5A depicts a block diagram of a portion of a 5G system, in accordance with some example embodiments;

[0016] FIG. 5B depicts an example system including at least one idle mode user equipment (UE), in accordance with some example embodiments;

[0017] FIG. 6 depicts a process flow at a network node such as a gNB type base station, in accordance with some example embodiments;

[0018] FIG. 7 depicts a process flow at a user equipment, in accordance with some example embodiments;

[0019] FIG. 8A depicts an example of configuration where type 1 channel search space (CSS) candidates matches the type 3 channel search space (CSS) candidates, in accordance with some example embodiments;

[0020] FIG. 8B depicts an example of a network node, in accordance with some example embodiments; and [0021] FIG. 9 depicts an example of an apparatus, in accordance with some example embodiments.

[0022] Like labels are used to refer to same or similar items in the drawings.

Detailed Description

[0023] In new radio-unlicensed (NR-U), frame based equipment may be used to access the unlicensed spectrum (also referred to license exempt spectrum). The frame based equipment’s channel access mechanism may be in accordance with regulatory requirements, such as ETSI EN 301 893. As noted, frame based equipment may be required to implement a listen before talk (LBT) based channel access mechanism to enable coexistence with other devices. The frame based equipment may use LBT to detect the presence of other radio transmissions on an operating channel. Moreover, the frame based device may be an initiating device that initiates an access request for the unlicensed spectrum using, for example, LBT.

And, the frame based device may also be a responding device that may access the unlicensed spectrum in response to the initiating device obtaining access, during the channel occupancy time (COT), of unlicensed spectrum resources.

[0024] FIG. 1 depicts an example LBT framework including fixed frame periods 102A, B, and so forth. The frame based equipment’s listening time is labeled as “CCA” 104A, B, and so forth (clear channel assessment). For example, when the frame based device seeks to transmit, the frame based equipment detects an energy level at a designated time for duration equal to a CCA period. If the energy level in the channel is below a CCA threshold, the frame equipment may proceed with a transmission during the channel occupancy time (COT), such as such as COTs 106 A, B, and so forth. Each time the frame equipment seeks to transmit via the unlicensed spectrum, the frame base equipment repeats the LBT’s CCA procedure noted above. At FIG. 1, within each fixed frame period (FFP), the channel occupancy time (COT) acquired by the initiating device is not be greater than 95% of the fixed frame period. And, at the tail of each fixed frame period, an idle period (see, e.g., idle periods 108A, 108B, and so forth) of at least 5% of the channel occupancy time should be left but with a minimum idle period of 100 microseconds (ps) in accordance with ETSI requirements.

[0025] To illustrate, the initiating device may occupy the channel at the beginning of a fixed frame period after a one-shot LBT. The initiating device may initiate transmission from the beginning of one or more fixed frame periods. Within a fixed frame period, an initiating device serve multiple transmissions in different link directions (e.g., uplink or downlink). And within a fixed frame period, an initiating device may grant an authorization to one or more associated responding devices to transmit on the current operating channel during the fixed frame period. The operation through a fixed frame period framework includes periodic timing with a periodicity equal to the fixed frame period. According to the ETSI regulatory requirements, the fixed frame period can be within a range of 1 to 10 milliseconds (ms). And, the fixed frame period may have its period changed (within the noted range, for example) no more than once every 200 milliseconds.

[0026] To illustrate further by way of an example, a base station, such as a gNB type base station, may operate on licensed spectrum as well as on an unlicensed spectrum band, such as the 5 GHz unlicensed band. This gNB may operate as an initiating device, and thus follow the frame based equipment framework. Based on this framework and the noted regulatory requirement for example, a frame based equipment’s frame structure may thus be implemented by the gNB to initiate transmission in the unlicensed spectrum.

[0027] FIG. 2 depicts an example of this frame structure 200, which may repeat over time. The frame structure 200 may include a fixed frame period 202, which may include one or more slot numbers 204A-H, designating a transmit or receive resource. The frame period 202 may also include a portion for the channel occupancy time 206 with a tail idle period 208 (which would precede another channel occupancy time for the next fixed frame period). The frame structure 200 in this example corresponds to the parameters listed in Table 1. This frame based equipment frame structure including the parameters may be indicated to a user equipment through high layer signaling, such as via a system information block (SIB), physical (LI) signaling (e.g., via downlink control information (DCI)), and/or the like.

[0028] Table 1 : An example of parameter configuration for FBE-based FS

[0029] For 5G NR-U, there may be support for frame based equipment operation as noted. In frame based equipment, the gNB base station may acquire a channel occupancy time with Cat 2 LBT (e.g., a LBT process without a random backoff) immediately prior to the fixed frame period. Within the gNB acquired channel occupancy time, if a gap is less than or equal to 16 microsecond for example, the Cat 1 LBT (e.g., an immediate transmission LBT) may be used by the gNB. Within the gNB acquired channel occupancy time, if a gap is greater than 16 microsecond for example, Cat 2 may be used by the gNB. For frame based equipment operation in NR-U, the gNB may be considered an initiating device as noted, while the one or more user equipment (UE) (which are being served by the gNB) may be considered as the responding device(s). The gNB may acquire a channel occupancy time by performing a LBT, such as a one-shot LBT, and all downlink and/or uplink transmission may be transmitted (by the gNB or associated UEs acting as responding devices), within the time period of the channel access time acquired by the gNB.

[0030] To illustrate by way of another example, the UE may operate as a responding device. In some instances, the UE may operating according to, for example, ETSI rules defined for a responding device, but the UE may not need to perform LBT. In some instances, the responding device UE may perform LBT depending on the gap between UE receive and the UE transmit. If the gap is smaller than 16 microseconds, the UE may operate according to Catl rules (e.g., with no LBT). If the gap is greater than or equal to 16 microseconds, the UE may perform a one-shot LBT before transmission (in which case the UE may need to find an unoccupied in order to transmit). When an idle UE transmits PRACH according to rules defined for a responding devices, the idle UE may perform a one-shot LBT before transmissions.

[0031] In the case or a two-step random access channel (RACH) procedure, the two- step may reduce the latency of RACH procedure as compared to a four-step RACH procedure. However, the two-step RACH procedure may result in increased uplink overhead between the UE and gNB. The four-step RACH may include the UE sending to the base station a first message (Msgl), which is the physical random access channel (PRACH) preamble carrying the RA-RNTI (random access-radio network temporary identifier). The second message (Msg2) is the base station sending to the UE a PRACH response including a RA-RNTI. The third message (Msg3) is the UE sending to the base station a radio resource control (RRC) connection request. The fourth message (Msg4) is the base station responding with a RRC connection setup message.

[0032] FIG. 3 depicts an example two-step RACH procedure between the UE 310 and gNB 320. In the two-step RACH, the first message 350 (labeled MsgA) condenses, into the Msg A 350, the four-step RACH’s first message Msgl and the four-step’s the third message (Msg3), so first message 350 includes the RACH preamble and a physical uplink shared channel (PUSCH) occasion for sending uplink data. Similarly, the two-step’s second message 360 (labeled MsgB) condenses the four-step’s Msg2 and the four-step’s Msg4, so the second message, MsgB 360, includes the PRACH response and physical downlink shared channel (PDSCH) as shown at FIG. 3. [0033] Regarding the group common physical downlink control channel (GC-PDCCH) content, the UE may be configured, via the RRC signaling, with downlink control information (DCI) including format size, radio network temporary identifier (RNTI), and the like as shown in FIG. 4A. The gNB may transmit to a group of one or more UEs a GC-PDCCH. The GC- PDCCH may provide control information to the one or more UEs. The UE may also be configured with a TYPE3 search-space with aggregation level 1 or 2 PDCCH candidates as shown in FIG. 4B. The UE may also be provided, via the RRC signaling, with a configuration for a search space set ⁵ and a corresponding control resource set (CORESET) P for monitoring PDCCH candidates for DCI format 2 0 with a control channel element (CCE) aggregation level

, wherein the CCEs as described in subclause 10.1 of 3GPP TS 38.213

(V15.7.0, 2019-0). The

PDCCH candidates may be the first

PDCCH candidates (e.g., one or two) for CCE aggregation level ^{/SI 1} for search space set ⁵ in CORESET P . The GC-PDCCH may include indication of sub-bands of a carrier bandwidth part (BWP) that are being used for transmission by gNB and slot format information (SFI).

[0034] In order to transmit the first RACH message (e.g., Msgl of the four-step RACH and/or Msgl of the two-step RACH) in a fixed frame period, an idle UE may enter into a listen before talk (LBT) clear channel assessment (CCA) period of a fixed frame period. This UE may then need to acquire the fixed frame period for itself. By acquiring the fixed frame period to do a RACH, the UE may block a gNB from using that whole fixed frame period just to transmit a short RACH procedure message. This is may not be an efficient use of spectrum. Furthermore, it is unclear whether the UE may operate according to the frame based equipment rules currently being defined for an initiating device by the ETSI BRAN (see, e.g., section

4.2.7.3.1.4 and 4.2.7.3.1.5 of ETSI EN 301 893. [0035] Another approach for the idle UE is to let the gNB obtain the fixed frame period, and then allow the idle UE to access the fixed frame period as a responding device. The gNB may not always obtain the channel. And the UE transmitting PRACH may not always obtain the channel (e.g., if the UE is unsuccessful in obtaining a channel via LBT). For example, the UE transmitting PRACH according to rules defined for responding device may be able to adapt to this scenario. The same holds for the gNB operating as the initiating device. The idle UE (which may have knowledge of the fixed frame period) may determine that the gNB acquired channel occupancy time (COT) based on existing initial access signals, such as the signal synchronization block (SSB) or the RMSI (remaining minimum system information, SystemlnformationBlockTypel) PDCCH monitoring window. However, it may not be practical or even possible to have these initial access signals present in each fixed frame period carrying a PRACH. As such, the channel occupancy time detection may need to be based on PDCCH monitoring and, in particular, GC -PDCCH monitoring. To that end, there is provided a way for the UE to detect a predefined PDCCH at least from the fixed frame periods that contain one or more physical random access channel (PRACH) opportunities. The GC -PDCCH may be used for this purpose as the GC -PDCCH may be transmitted by a gNB in every fixed frame period to indicate to the UEs the transmission direction within the fixed frame period. However, the GC- PDCCH configuration may require a relatively large overhead and would not fit in the RMSI (remaining minimum system information, SystemlnformationBlockTypel) as the RMSI has relatively limited capabilities due as it operates with a fixed modulation and coding scheme, for example).

[0036] In some example embodiments, there is provided a reduced GC -PDCCH configuration and a new UE behavior, which enables the delivery of the same GC -PDCCH to idle UEs and connected UEs. This may be achieved by having the gNB configure PDCCH monitoring for idle UEs as a subset of GC -PDCCH defined for the RRC connected UEs. This subset may include the following parameters: monitoring occasion, PDCCH candidates, CORESET configuration, DCI payload, and/or RNTI, in accordance with some example embodiments.

[0037] Regarding the monitoring occasion included in the GC -PDCCH, this is a subset (intended for only the idle mode UEs) of monitoring occasions configured for GC -PDCCH. In some example embodiments, the monitoring occasions are determined based on fixed frame period configuration and a PRACH configuration. In some example embodiments, the idle UE monitors the GC -PDCCH at the beginning of each fixed frame period having a PRACH or first message RACH message (e.g. MsgA or Msgl noted above) transmission opportunity.

[0038] Regarding PDCCH candidates included in the GC-PDDCH, this is a subset (intended for only the idle mode UEs) of PDCCH candidates configured for GC -PDCCH. The UE (which is in idle mode) may monitor a predefined number of PDCCH candidates with a predefined aggregation level. For example, one PDCCH candidate with aggregation level L =

8. The PDCCH candidates for the idle UE may be determined based on a specification or may be configured by RMSI (remaining minimum system information, SystemlnformationBlockTypel).

[0039] With respect to the CORESET configuration included in the GC-PDDCH, this may be common for idle UEs and RRC connected UEs (both are associated with CORESET#0 or CommonControlResourceSet configured in a master information block (MIB) or RMSI, respectively).

[0040] Regarding the DCI payload included in the GC-PDDCH, this may be common for idle UEs and RRC connected UEs. The DCI payload may be configured by RMSI, or the DCI payload can be determined by the specification. [0041] With respect to the RNTI, this may be common for idle UEs and RRC connected UEs. The RNTI can be configured via the RMSI or may be determined based on a specification.

[0042] Regarding the gNB’s transmission of the GC-PDCCH, at least once during fixed frame period containing a PRACH opportunity (preferably at the beginning of each fixed frame period), the gNB may transmit GC-PDCCH according to the PDCCH monitoring configuration supported by the idle UEs to provide the idle mode UE with the subset configuration. As noted, the subset configuration may include the following parameters: monitoring occasion, PDCCH candidates, CORESET configuration, DCI payload, and/or RNTI, in accordance with some example embodiments. For other monitoring occasions, the gNB may transmit the GC-PDCCH according to GC-PDCCH configuration.

[0043] The UE may, as noted, detect the GC-PDCCH. When a GC-PDCCH is detected by an idle UE for example, the UE may discard the entire GC-PDCCH content and be allowed to transmit PRACH within the fixed frame period in which the GC-PDCCH is detected. The idle UEs (which is still in the RACH phase) cannot use the GC-PDCCH content because the idle UEs do not know how the payload is structured. But the FFP configuration may be provided in the RMSI.

[0044] In some embodiments, certain bits of the GC-PDCCH payload may be used as relevant payload for an idle UE. These bits may or may not be relevant for RRC connected UEs. For example, there may be predetermined bits which may indicate a FFP duration (in slots) counted from the slot containing GC-PDCCH. In this embodiment, the UE may then determine whether a certain PRACH opportunity is within this window. Another option is that gNB may indicate (e.g., by a bit) whether a next PRACH opportunity following the GC- PDCCH slot is within the same FFP (e.g., 1= yes, 0=no). When the GC-PDCCH is detected by connected UE, the UE may interpret the content of the DCI according to SFI configuration. [0045] Before providing additional details, a system 500 block diagram of a reference architecture for 5G is depicted at FIG. 5A, in accordance with some example embodiments.

The 5G system may include a UE 564, a radio access network (RAN) 570 (e.g., a gNB providing a radio access network serving one or more UEs), an Access and Mobility Management Function (AMF) 572, a User Data Management (UDM) function 574, a Session Management Function (SMF) 576, a Policy Control Function (PCF) 580, an authentication function (AUSF) 588, an Application Function (AF) 550, and a data network 555.

[0046] FIG. 5B depicts an RRC connected UE 564A and an idle mode UE 564B served by one or more base stations 570A-B having corresponding serving areas (e.g., cells) 570A-B. For example, a UE may be connected to a primary cell 570A through the base station 572A (e.g., a gNB) and a secondary cell 570B through the base station 572B (e.g., a gNB, WiFi access point, etc.). Here, the two cells 570A-B are at least partially overlapping. In this example, the primary cell 570 A may operate on a licensed band, and the secondary cell 570B may operate on an unlicensed band, such as 5 GHz band. However, the secondary cell may operate also on a licensed band as well. When operating on the unlicensed band, access to the unlicensed spectrum may be in accordance with the listen before talk framework noted herein.

[0047] Although in the example of FIG. 5B there are just one primary cell and one secondary depicted, any number of cells operating on licensed and/or unlicensed bands may be provided. Moreover, these cells may operate to provide carrier aggregation (CA) as well as dual connectivity (e.g., across two base stations), standalone operation in the unlicensed spectrum, and/or the like. Although shown in different base stations, the primary cell and secondary cell may be coriocated in the same base station.

[0048] FIG. 6 depicts an example of a process 600 for a base station, such as a gNB, to configure idle mode UEs, in accordance with some example embodiments. [0049] At 605, the base station, such as the gNB, may configure GC-PDCCH monitoring at an idle mode UE to be a subset of the GC-PDCCH configured for an RRC connected UE. For RRC connected UEs, the GC-PDCCH is defined by a SFI (see, e.g., FIG.

4 A), and the related search space configuration (see, e.g., FIG. 4B). The idle UEs may be configured with at least subset of this search space configuration, such as aggregation layers, monitoring occasions, and the like. This allows to use the same GC-PDCCH for two different UE types In some variants, at least a subset denotes that two different UE types are configured with at least one common PDCCH candidate in at least one monitoring occasion. To illustrate by way of example, the gNB 572A may configure the idle mode UE 564A to use a subset of the GC-PDDCH being used for the RRC connected mode UE 564N. The gNB may configure the idle mode UE via a SIB, such as the RMSI. As noted above, the subset may include at least the following parameters: monitoring occasion, PDCCH candidates, CORESET configuration, DCI payload, and/or RNTI.

[0050] At least one of the monitoring GC-PDCCH candidates within a fixed frame period channel occupancy time may be configured to be common between the idle mode UE and the RRC connected UE. Moreover, the PDCCH candidates for an idle UE may be determined by specification or it may be configured by SIB. Some of the idle mode UE’s PDCCH candidates may be different than the RRC connected UE’s PDCCH candidates. Furthermore, the CORESET, payload, and RNTI may be configured to be common to the idle mode UEs and RRC connected node UEs.

[0051] At 610, the gNB may transmits the GC-PDCCH according to the PDCCH monitoring configuration supported by idle UEs, in accordance with some example embodiments. This may be performed at least once during a fixed frame period channel occupancy time containing a RACH occasion, such as at the beginning of a channel occupancy time. It may be up to the gNB scheduling decision to send GC-PDCCH. For FFPs containing PRACH opportunities, the gNB may always transmit — provided that LBT is positive with respect to a channel opportunity. Otherwise, the idle UEs may not be able to transmit the PRACH.

[0052] At 620, the gNB may receive from at least one idle UE a RACH within the channel occupancy time. For example, the gNB may receive, via the PRACH on the uplink, a RACH message. For example, the RACH message may be PRACH related to a 4-step RACH procedure or MsgA of the 2-step RACH procedure. RACH message reception presumes that the UE was able to successfully find a COT via the LBT. It may also presume that the UE LBT preceding RACH message transmission was successful.

[0053] FIG. 7 depicts an example of a process 700 for an idle UE, in accordance with some example embodiments.

[0054] At 710, the idle UE may receive a configuration for GC-PDCCH monitoring by SIB (e.g., the RMSI) containing at least RNTI, payload size and search-space configuration such as GC-PDCCH monitoring occasions and PDCCH candidates, in accordance with some example embodiments. The search space may include at least the monitoring occasions relevant for idle UEs. They can be determined with respect to SSB and/or PRACH occasions. The PDCCH candidates may determine the number of candidates for each aggregation layer. Some of the parameters may be determined by a standard or specification, instead of RMSI.

[0055] At 720, the idle UE may determine a need to send RACH. For example, in the case of UE-initiated data transmission or in response to a paging message, the idle UE may send a RACH message.

[0056] At 725, the idle UE may determine a RACH occasions to transmit. For example, UE may read the PRACH resources from RMSI (e.g., the RMSI is part of synchronization signal block of the cell). The synchronization signal block may be beamformed to the UE, so there may be multiple SSBs within a given cell, each SSB associated with a set of RACH occasions

[0057] At 730, the idle UE may determine at least one GC-PDCCH monitoring candidate preceding the RACH occasion. This corresponds to PDCCH monitoring according to the PDCCH configuration. The idle UE may only need to perform monitoring when the idle mode UE reason to transmit PRACH (e.g., due to UE initiated data transmission or in response to a page message).

[0058] At 740, the idle UE may determine, based on GC-PDCCH monitoring, whether the gNB acquired channel occupancy time is available during the PRACH preamble. If available (yes at 740), the UE may transmit, at 760, via the PRACH. If not available (no at 740), the UE may return to 725. PRACH resource is periodical. If the current attempt fails, then UE tries again in the next opportunity.

[0059] When the network, such as a gNB, configures the idle UEs in a RMSI with a fixed frame period configuration, the configuration may include: an FBE flag, a FFP timing, and FFP-RNTI, a given DCI payload size X, and a given aggregation level L. Alternatively, the FBE flag may be determined implicitly (e.g., based on the FBE-specific information elements). Regarding the FFP timing (e.g., start, length, etc.), the start timing may be determined with respect to the SSB transmission. For example, FFP timing may be an offset compared to SSB- slot, while FFP length may be determined in terms of slots.

[0060] With the RRC connected UEs, these UEs may receive the GC-PDCCH, which may include: SFI-RNTI slot combinations, DCI payload size, RNTI, and a TYPE 3 common search-space-set. The payload sixe may be set to X and the SFI-RNTI may be set equal to FFP- RNTI. With respect to the common search space, there may be matching (with the idle mode UEs) at least one of the TYPE1 or TYPE0 search-space set PDCCH candidates. And, one or two candidates of aggregation level L. [0061] In order to enable at least one candidate from TYPE-3 search-space-set to match TYPE-0/1 search-space-set, the gNB may take into account the TYPEO/1 default number of PDCCH candidates as defined in Table 2 below (see, e.g., 3GPP TS 38.213).

[0062] Table 2: CCE aggregation levels and maximum number of PDCCH candidates per CCE aggregation level for CSS sets configured by searchSpace-SIBl.

[0063] Therefore, for TYPE-3 search-space set, the gNB may configure the same configuration or a configuration where there is an integer (or fractional) multiple of the candidates of Table 2, an example of which is shown at FIG. 8A. When this is the case, the TYPE3 search-space-set has half the candidates of AL4 compared to default TYPE1 search- space-set. This results in one common PDCCH candidate. Further, at least one monitoring occasion in of TYPE-1 CSS may correspond to that of TYPE-3 CSS. And both search-space sets have to be in the same CORESET (i.e. ControlResourceSetZero or

CommonControlResourceSet ). At FIG. 8A, the TYPE1-CSS refers to the search space set used for scheduling RACH Msg 2, and Type3 CSS refers to the common search space used for scheduling (e.g, GC-PDCCH (SFI-RNTI)).

[0064] FIG. 8B depicts a block diagram of a network node 800, in accordance with some example embodiments. The network node 800 may be configured to provide one or more network side functions, such as a base station, AMF, PCF, AF, and/or other network nodes.

[0065] The network node 800 may include a network interface 802, a processor 820, and a memory 804, in accordance with some example embodiments. The network interface 802 may include wired and/or wireless transceivers to enable access other nodes including base stations, devices 152-180, the Internet, and/or other nodes. The memory 804 may comprise volatile and/or non-volatile memory including program code, which when executed by at least one processor 820 provides, among other things, the processes disclosed herein with respect to the network node.

[0066] In some example embodiments, the apparatus may comprise a base station such as a gNB. The base station may configure, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment.

[0067] In some example embodiments, the base station may transmit a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

[0068] In some example embodiments, the base station may receive a random access channel message (e.g., the 4-stage RACH process Msgl preamble, or the 2-stage RACH MsgA) during a random access channel occasion within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

[0069] In some example embodiments, the subset includes one or more monitoring occasions, one or more physical downlink control channel candidates, a control resource set, a downlink control information payload, and a radio network temporary identifier. In some example embodiments, the group common physical downlink control channel monitoring is within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum. In some example embodiments, the group common physical downlink control channel monitoring includes monitoring a group common physical downlink control channel candidate, wherein the group common physical downlink control channel candidate includes configuration information common between the idle user equipment and the radio resource control connected user equipment, and/or wherein the group common physical downlink control channel candidate includes configuration information that is different between the idle user equipment and the radio resource control connected user equipment. In some example embodiments, the group common physical downlink control channel candidate is specified by a standard and/or provided by the system information block comprising a remaining minimum system information, and/or wherein the configuration information that is common includes a control resource set, a downlink control information payload, and a radio network temporary identifier. In some example embodiments, the group common physical downlink control channel is transmitted during a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum. In some example embodiments, the channel occupancy time includes a random access channel occasion. In some example embodiments, the random access channel occasion may be within the channel occupancy time. In some example embodiments, the transmitted group common physical downlink control channel is transmitted to the idle user equipment, and wherein the transmitted group common physical downlink control channel includes a downlink control information payload that indicates an end to a channel occupancy time of a fixed frame period and/or that indicates whether an associated physical random access channel resource is part of the channel occupancy time acquired by the apparatus.

[0070] FIG. 9 illustrates a block diagram of an apparatus 10, in accordance with some example embodiments.

[0071] The apparatus 10 may include at least one antenna 12 in communication with a transmitter 14 and a receiver 16 Alternatively transmit and receive antennas may be separate. The apparatus 10 may also include a processor 20 configured to provide signals to and receive signals from the transmitter and receiver, respectively, and to control the functioning of the apparatus. Processor 20 may be configured to control the functioning of the transmitter and receiver by effecting control signaling via electrical leads to the transmitter and receiver. Likewise, processor 20 may be configured to control other elements of apparatus 10 by effecting control signaling via electrical leads connecting processor 20 to the other elements, such as a display or a memory. The processor 20 may, for example, be embodied in a variety of ways including circuitry, at least one processing core, one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and/or the like), or some combination thereof. Accordingly, although illustrated in FIG. 9 as a single processor, in some example embodiments the processor 20 may comprise a plurality of processors or processing cores.

[0072] The apparatus 10 may be capable of operating with one or more air interface standards, communication protocols, modulation types, access types, and/or the like. Signals sent and received by the processor 20 may include signaling information in accordance with an air interface standard of an applicable cellular system, and/or any number of different wireline or wireless networking techniques, comprising but not limited to Wi-Fi, wireless local access network (WLAN) techniques, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, and/or the like. In addition, these signals may include speech data, user generated data, user requested data, and/or the like.

[0073] For example, the apparatus 10 and/or a cellular modem therein may be capable of operating in accordance with various first generation (1G) communication protocols, second generation (2G or 2.5G) communication protocols, third-generation (3G) communication protocols, fourth-generation (4G) communication protocols, fifth-generation (5G) communication protocols, Internet Protocol Multimedia Subsystem (IMS) communication protocols (for example, session initiation protocol (SIP) and/or the like. For example, the apparatus 10 may be capable of operating in accordance with 2G wireless communication protocols IS-136, Time Division Multiple Access TDMA, Global System for Mobile communications, GSM, IS-95, Code Division Multiple Access, CDMA, and/or the like. In addition, for example, the apparatus 10 may be capable of operating in accordance with 2.5G wireless communication protocols General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), and/or the like. Further, for example, the apparatus 10 may be capable of operating in accordance with 3G wireless communication protocols, such as Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Time Division- Synchronous Code Division Multiple Access (TD-SCDMA), and/or the like. The apparatus 10 may be additionally capable of operating in accordance with 3.9G wireless communication protocols, such as Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and/or the like. Additionally, for example, the apparatus 10 may be capable of operating in accordance with 4G wireless communication protocols, such as LTE Advanced, 5G, and/or the like as well as similar wireless communication protocols that may be subsequently developed.

[0074] It is understood that the processor 20 may include circuitry for implementing audio/video and logic functions of apparatus 10. For example, the processor 20 may comprise a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, and/or the like. Control and signal processing functions of the apparatus 10 may be allocated between these devices according to their respective capabilities. The processor 20 may additionally comprise an internal voice coder (VC) 20a, an internal data modem (DM) 20b, and/or the like. Further, the processor 20 may include functionality to operate one or more software programs, which may be stored in memory. In general, processor 20 and stored software instructions may be configured to cause apparatus 10 to perform actions. For example, processor 20 may be capable of operating a connectivity program, such as a web browser. The connectivity program may allow the apparatus 10 to transmit and receive web content, such as location-based content, according to a protocol, such as wireless application protocol, WAP, hypertext transfer protocol, HTTP, and/or the like.

[0075] Apparatus 10 may also comprise a user interface including, for example, an earphone or speaker 24, a ringer 22, a microphone 26, a display 28, a user input interface, and/or the like, which may be operationally coupled to the processor 20. The display 28 may, as noted above, include a touch sensitive display, where a user may touch and/or gesture to make selections, enter values, and/or the like. The processor 20 may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker 24, the ringer 22, the microphone 26, the display 28, and/or the like. The processor 20 and/or user interface circuitry comprising the processor 20 may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, for example, software and/or firmware, stored on a memory accessible to the processor 20, for example, volatile memory 40, non-volatile memory 42, and/or the like. The apparatus 10 may include a battery for powering various circuits related to the mobile terminal, for example, a circuit to provide mechanical vibration as a detectable output. The user input interface may comprise devices allowing the apparatus 20 to receive data, such as a keypad 30 (which can be a virtual keyboard presented on display 28 or an externally coupled keyboard) and/or other input devices.

[0076] As shown in FIG. 9, apparatus 10 may also include one or more mechanisms for sharing and/or obtaining data. For example, the apparatus 10 may include a short-range radio frequency (RF) transceiver and/or interrogator 64, so data may be shared with and/or obtained from electronic devices in accordance with RF techniques. The apparatus 10 may include other short-range transceivers, such as an infrared (IR) transceiver 66, a Bluetooth™ (BT) transceiver 68 operating using Bluetooth™ wireless technology, a wireless universal serial bus (USB) transceiver 70, a Bluetooth™ Low Energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and/or any other short-range radio technology. Apparatus 10 and, in particular, the short-range transceiver may be capable of transmitting data to and/or receiving data from electronic devices within the proximity of the apparatus, such as within 10 meters, for example. The apparatus 10 including the Wi-Fi or wireless local area networking modem may also be capable of transmitting and/or receiving data from electronic devices according to various wireless networking techniques, including 6LoWpan, Wi-Fi, Wi-Fi low power, WLAN techniques such as IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and/or the like.

[0077] The apparatus 10 may comprise memory, such as a subscriber identity module (SIM) 38, a removable user identity module (R-UIM), an eUICC, an UICC, and/or the like, which may store information elements related to a mobile subscriber. In addition to the SIM, the apparatus 10 may include other removable and/or fixed memory. The apparatus 10 may include volatile memory 40 and/or non-volatile memory 42. For example, volatile memory 40 may include Random Access Memory (RAM) including dynamic and/or static RAM, on-chip or off-chip cache memory, and/or the like. Non-volatile memory 42, which may be embedded and/or removable, may include, for example, read-only memory, flash memory, magnetic storage devices, for example, hard disks, floppy disk drives, magnetic tape, optical disc drives and/or media, non-volatile random access memory (NVRAM), and/or the like. Like volatile memory 40, non-volatile memory 42 may include a cache area for temporary storage of data.

At least part of the volatile and/or non-volatile memory may be embedded in processor 20. The memories may store one or more software programs, instructions, pieces of information, data, and/or the like which may be used by the apparatus for performing operations disclosed herein. Alternatively or additionally, the apparatus may be configured to cause the operations disclosed herein with respect to the base stations/WLAN access points and network nodes including the UEs.

[0078] The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus 10. The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus 10. In the example embodiment, the processor 20 may be configured using computer code stored at memory 40 and/or 42 to the provide operations disclosed herein with respect to the UE.

[0079] Some of the embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and/or hardware may reside on memory 40, the control apparatus 20, or electronic components, for example. In some example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer- readable media. In the context of this document, a “computer-readable medium” may be any non-transitory media 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 or data processor circuitry, with examples depicted at FIG. 9, computer-readable medium may comprise a non-transitory computer-readable storage medium that may be any media that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0080] In some example embodiments, apparatus 10 may be comprised in or comprise a user equipment. In some example embodiments, the user equipment may determine a random access channel occasion for transmission. In some example embodiments, the user equipment may determine a group common physical downlink control channel monitoring candidate preceding the random access channel occasion. In some example embodiments, the user equipment may determine, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble. In some example embodiments, the user equipment may transmit, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.

[0081] When the channel occupancy time is not available during the physical random access channel preamble, the user equipment may determine another random access channel occasion for transmission, in accordance with some example embodiments. When channel occupancy time is available during the physical random access channel occasion, the user equipment may transmit a random access channel preamble during the random access channel occasion for transmission, in accordance with some example embodiments. In some example embodiments, the user equipment may determine availability based on the group common physical downlink control channel received in a fixed frame period including the random access channel occasion, and wherein the apparatus is further caused to at least discard at least a portion of a payload of the received group common physical downlink control channel. In some example embodiments, the user equipment may determine availability based on the group common physical downlink control channel indicating an end time for the channel occupancy time, wherein the end time is a time that is the same or later than the random access channel occasion. In some example embodiments, the user equipment may determine the channel occupancy time based on a system information block comprising a remaining minimum system information. When the apparatus is in idle mode, the user equipment may determine whether the physical random access channel opportunity is within the channel occupancy time being acquired by a base station.

[0082] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein may be enabling the gNB to indicate GC-PDCCH content to a connected UE and indicating acquired FFP toan idle UE using the same PDCCH. This may minimize DCI overhead and configuration overhead for both idle UEs and RRC connected UEs.

[0083] Although some of the embodiments are applicable to frame based equipment, load base equipment may also utilize the embodiments disclosed herein. For example, a load based device, such as a UE, may send a PRACH according to Cat2 LBT (rather than Cat4 LBT). This may minimize the deviation between the two mode of operations of LBT and FBE. Moreover, certain bits of the payload of the GC-PDCCH may be used, as noted above. For example, there may be a given quantity of predetermined bits (e.g., 1 bit, 2 bits, 3 bits, or more), which indicate FFP duration (in slots) counted from the slot containing PDCCH. In this example, the UE may then determine the whether certain PRACH opportunity is within this window. Alternatively, the gNB may indicate by a bit for example, whether a given PRACH opportunity following a PDCCH slot is within the same FFP (e.g., a 1= yes, and a 0=no).

[0084] The subject matter described herein may be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. For example, the base stations and user equipment (or one or more components therein) and/or the processes described herein can be implemented using one or more of the following: a processor executing program code, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), an embedded processor, a field programmable gate array (FPGA), and/or combinations thereof. These various implementations may include implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. These computer programs (also known as programs, software, software applications, applications, components, program code, or code) include machine instructions for a programmable processor, and may be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the term “computer-readable medium” refers to any computer program product, machine-readable medium, computer-readable storage medium, apparatus and/or device (for example, magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions. Similarly, systems are also described herein that may include a processor and a memory coupled to the processor. The memory may include one or more programs that cause the processor to perform one or more of the operations described herein.

[0085] Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations may be provided in addition to those set forth herein. Moreover, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed above. Other embodiments may be within the scope of the following claims.

[0086] If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Although various aspects of some of the embodiments are set out in the independent claims, other aspects of some of the embodiments comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes example embodiments, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications that may be made without departing from the scope of some of the embodiments as defined in the appended claims. Other embodiments may be within the scope of the following claims. The term “based on” includes “based on at least.” The use of the phase “such as” means “such as for example” unless otherwise indicated.

Claims

WHAT IS CLAIMED

1. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least: configure, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and transmit a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

2. The apparatus of claim 1, wherein the apparatus is further caused to at least: receive a random access channel message during a random access channel occasion within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

3. The apparatus of any of claims 1-2, wherein the subset includes one or more monitoring occasions, one or more physical downwlink control channel candidates, a control resource set, a downlink control information payload, and a radio network temporary identifier.

4. The apparatus of any of claims 1-3, wherein the group common physical downlink control channel monitoring is within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

5. The apparatus of any of claims 1-4, wherein the group common physical downlink control channel monitoring includes monitoring a group common physical downlink control channel candidate, wherein the group common physical downlink control channel candidate includes configuration information common between the idle user equipment and the radio resource control connected user equipment, and/or wherein the group common physical downlink control channel candidate includes configuration information that is different between the idle user equipment and the radio resource control connected user equipment.

6. The apparatus of claim 5, wherein the group common physical downlink control channel candidate is specified by a standard and/or provided by the system information block comprising a remaining minimum system information, and/or wherein the configuration information that is common includes a control resource set, a downlink control information payload, and a radio network temporary identifier.

7. The apparatus of any of claims 1-6, wherein the group common physical downlink control channel is transmitted during a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

8. The apparatus of claim 7, wherein the channel occupancy time includes a random access channel occasion.

9. The apparatus of claim 8, wherein the random access channel occasion is within the channel occupancy time.

10. The apparatus of any of claims 1-9, wherein the transmitted group common physical downlink control channel is transmitted to the idle user equipment, and wherein the transmitted group common physical downlink control channel includes a downlink control information payload that indicates an end to a channel occupancy time of a fixed frame period and/or that indicates whether an associated physical random access channel resource is part of the channel occupancy time acquired by the apparatus.

11. The apparatus of any of claims 1-10, wherein the apparatus comprises or is comprised in a base station.

12. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least: receive, via a system information block, a configuration to enable monitoring of a group common physical downlink control channel, the system information block including at least a radio network temporary identifier, a downlink payload size, and a search-space configuration that defines monitoring occasions for one or more group common physical downlink control channel candidates; determine a random access channel occasion for transmission; determine a group common physical downlink control channel monitoring candidate preceding the random access channel occasion; determine, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble; and transmit, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.

13. The apparatus of claim 12, wherein the apparatus, when the channel occupancy time is not available during the physical random access channel preamble, is further caused to at least determine another random access channel occasion for transmission, and/or wherein the determination of whether the channel occupancy time is available during a physical random access channel preamble is further based on fixed frame period timing configured by a remaining minimum system information.

14. The apparatus of any of claims 12-13, wherein the apparatus, when channel occupancy time is available during the physical random access channel occasion, is further caused to at least transmit a random access channel preamble during the random access channel occasion for transmission.

15. The apparatus of any of claims 12-14, wherein the apparatus is further caused to at least determine availability based on the group common physical downlink control channel received in a fixed frame period including the random access channel occasion, and wherein the apparatus is further caused to at least discard at least a portion of a payload of the received group common physical downlink control channel.

16. The apparatus of any of claims 12-15, wherein the apparatus is further caused to at least determine availability based on the group common physical downlink control channel indicating an end time for the channel occupancy time, wherein the end time is a time that is the same or later than the random access channel occasion.

17. The apparatus of any of claims 12-16, wherein the apparatus is further cause to at least determine the channel occupancy time based on a system information block comprising a remaining minimum system information.

18. The apparatus of any of claims 12-17, wherein when the apparatus is in idle mode, the apparatus is further caused to determine whether the physical random access channel opportunity is within the channel occupancy time being acquired by a base station.

19. The apparatus of any of claims 12-18, wherein the apparatus comprises or is comprised in a user equipment.

20. A method comprising: configuring, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and transmitting a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

21. The method of claim 20, further comprising: receiving a random access channel message during a random access channel occasion within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

22. The method of any of claims 20-21, wherein the subset includes one or more monitoring occasions, one or more physical downlink control channel candidates, a control resource set, a downlink control information payload, and a radio network temporary identifier.

23. The method of any of claims 20-22, wherein the group common physical downlink control channel monitoring is within a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

24. The method of any of claims 20-23, wherein the group common physical downlink control channel monitoring includes monitoring a group common physical downlink control channel candidate, wherein the group common physical downlink control channel candidate includes configuration information common between the idle user equipment and the radio resource control connected user equipment, and/or wherein the group common physical downlink control channel candidate includes configuration information that is different between the idle user equipment and the radio resource control connected user equipment.

25. The method of claim 24, wherein the group common physical downlink control channel candidate is specified by a standard and/or provided by the system information block comprising a remaining minimum system information block, and/or wherein the configuration information that is common includes a control resource set, a downlink control information payload, and a radio network temporary identifier.

26. The method of any of claims 20-25, wherein the group common physical downlink control channel is transmitted during a channel occupancy time of a fixed frame period for listen before talk access of unlicensed spectrum.

27. The method of claim 26, wherein the channel occupancy time includes a random access channel occasion.

28. The method of claim 27, wherein the random access channel occasion is within the channel occupancy time.

29. The method of any of claims 20-28, wherein the transmitted group common physical downlink control channel is transmitted to the idle user equipment, and wherein the transmitted group common physical downlink control channel includes a downlink control information payload that indicates an end to a channel occupancy time of a fixed frame period and/or that indicates whether an associated physical random access channel resource is part of the channel occupancy time acquired by the apparatus.

30. An method comprising: receiving, via a system information block, a configuration to enable monitoring of a group common physical downlink control channel, the system information block including at least a radio network temporary identifier, a downlink payload size, and a search-space configuration that defines monitoring occasions for one or more group common physical downlink control channel candidates; determining a random access channel occasion for transmission; determining a group common physical downlink control channel monitoring candidate preceding the random access channel occasion; determining, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble; and transmitting, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.

31. The method of claim 30, wherein when the channel occupancy time is not available during the physical random access channel preamble, determining another random access channel occasion for transmission, and/or wherein the determining is further based on fixed frame period timing configured by a remaining minimum system information..

32. The method of any of claims 30-31, wherein when channel occupancy time is available during the physical random access channel occasion, transmitting a random access channel preamble during the random access channel occasion for transmission.

33. The method of any of claims 30-32, further comprising: determining availability based on the group common physical downlink control channel received in a fixed frame period including the random access channel occasion; and discarding at least a portion of a payload of the received group common physical downlink control channel.

34. The method of any of claims 30-33, further comprising: determining availability based on the group common physical downlink control channel indicating an end time for the channel occupancy time, wherein the end time is a time that is the same or later than the random access channel occasion.

35. The method of any of claims 30-34, further comprising: determining the channel occupancy time based on a system information block comprising a remaining minimum system information.

36. The method of any of claims 30-35, wherein when the apparatus is in idle mode, determining whether the physical random access channel opportunity is within the channel occupancy time being acquired by a base station.

37. An apparatus comprising: means for configuring, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and means for transmitting a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

38. The apparatus of claim 36 further comprising means for performing any of the functions recited in any of claims 21-29.

39. An apparatus comprising: means for receiving, via a system information block, a configuration to enable monitoring of a group common physical downlink control channel, the system information block including at least a radio network temporary identifier, a downlink payload size, and a search-space configuration that defines monitoring occasions for one or more group common physical downlink control channel candidates; means for determining a random access channel occasion for transmission; means for determining a group common physical downlink control channel monitoring candidate preceding the random access channel occasion; means for determining, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble; and means for transmitting, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.

40. The apparatus of claim 39 further comprising means for performing any of the functions recited in any of claims 31-36.

41. A non-transitory computer-readable storage medium including computer program code, which when executed by at least one processor, causes operations comprising: configuring, via a system information block, an idle user equipment for group common physical downlink control channel monitoring, the idle user equipment being configured with at least a subset of a configuration being used to configure radio resource control connected user equipment; and transmitting a group common physical downlink control channel according to the group common physical downlink control channel monitoring occasions configured for the idle user equipment.

_3«_

42. A non-transitory computer-readable storage medium including computer program code, which when executed by at least one processor, causes operations comprising: receiving, via a system information block, a configuration to enable monitoring of a group common physical downlink control channel, the system information block including at least a radio network temporary identifier, a downlink payload size, and a search-space configuration that defines monitoring occasions for one or more group common physical downlink control channel candidates; determining a random access channel occasion for transmission; determining a group common physical downlink control channel monitoring candidate preceding the random access channel occasion; determining, based on the determined group common physical downlink control channel monitoring candidate, whether a channel occupancy time is available during a physical random access channel preamble; and transmitting, via the physical random access channel preamble, a random access channel message, when the channel occupancy time is available.