Control resource set design for new radio-unlicensed operations with subband access

Design of control resource sets (CORESETs) is disclosed for new radio (NR) unlicensed (NR-U) operations with subband access. A default CORESET may be defined for multiple or all subbands within the allocated NR system bandwidth where each subband is covered by a sub-CORESET. When a decoding candidate of the set of decoding candidates spans the boundary of multiple sub-CORESETs, a base station may either remove the overlapping decoding candidate from the set of decoding candidates, shift the decoding candidate into the next location fully within a sub-CORESET, or continue transmission of the decoding candidate while puncturing the portion on the inaccessible subband. In the puncturing option, a user equipment (UE) would perform additional blind decoding in each subband according to the associated sub-CORESET. In additional aspects, after beginning of a transmission opportunity, the UE uses the knowledge of accessible subbands for fast CORESET switching via broadcast or UE-specific signaling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Indian Application No. 201841031080, entitled, “CORESET DESIGN FOR NR-U WITH SUBBAND ACCESS,” filed on Aug. 20, 2018, which is expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to control resource set (CORESET) design for new radio (NR) unlicensed (NR-U) operations with subband access.

Background

SUMMARY

In one aspect of the disclosure, a method of wireless communication includes scheduling, by a base station, transmission of a plurality of decoding candidates during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-control resource set (CORESET) of a CORESET allocated to the transmission opportunity, uniformly distributing, by the base station, the plurality of decoding candidates for a served user equipment (UE) into the CORESET, detecting, by the base station, at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs, and modifying, by the base station, transmission of the at least one decoding candidate in response to the detecting.

In an additional aspect of the disclosure, a method of wireless communication includes obtaining, by a UE, a set of decoding candidates, and performing, by the UE, one or more blind decoding procedures of one or more search spaces of a sub-CORESET associated with each subband of a plurality of subbands of a transmission opportunity on a shared communication channel, wherein the one or more blind decoding procedures are performed to detect at least one of the set of decoding candidates.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for scheduling, by a base station, transmission of a plurality of decoding candidates during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-CORESET of a CORESET allocated to the transmission opportunity, means for uniformly distributing, by the base station, the plurality of decoding candidates for a served UE into the CORESET, means for detecting, by the base station, at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs, and means for modifying, by the base station, transmission of the at least one decoding candidate in response to the means for detecting.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for obtaining, by a UE, a set of decoding candidates, and means for performing, by the UE, one or more blind decoding procedures of one or more search spaces of a sub-CORESET associated with each subband of a plurality of subbands of a transmission opportunity on a shared communication channel, wherein the one or more blind decoding procedures are performed to detect at least one of the set of decoding candidates.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to schedule, by a base station, transmission of a plurality of decoding candidates during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-CORESET of a CORESET allocated to the transmission opportunity, code to uniformly distribute, by the base station, the plurality of decoding candidates for a served UE into the CORESET, code to detect, by the base station, at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs, and code to modify, by the base station, transmission of the at least one decoding candidate, in response to the code to detect.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to obtain, by a UE, a set of decoding candidates, and code to perform, by the UE, one or more blind decoding procedures of one or more search spaces of a sub-CORESET associated with each subband of a plurality of subbands of a transmission opportunity on a shared communication channel, wherein the one or more blind decoding procedures are performed to detect at least one of the set of decoding candidates.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to schedule, by a base station, transmission of a plurality of decoding candidates during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-CORESET of a CORESET allocated to the transmission opportunity, to uniformly distribute, by the base station, the plurality of decoding candidates for a served UE into the CORESET, to detect, by the base station, at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs, and to modify, by the base station, transmission of the at least one decoding candidate in response to the configuration of the at least one processor to detect.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to obtain, by a UE, a set of decoding candidates, and to perform, by the UE, one or more blind decoding procedures of one or more search spaces of a sub-CORESET associated with each subband of a plurality of subbands of a transmission opportunity on a shared communication channel, wherein the one or more blind decoding procedures are performed to detect at least one of the set of decoding candidates.

DETAILED DESCRIPTION

FIG. 1is a block diagram illustrating 5G network100including various base stations and UEs configured according to aspects of the present disclosure. The 5G network100includes a number of base stations105and other network entities. A base station may be a station that communicates with the UEs and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each base station105may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a base station and/or a base station subsystem serving the coverage area, depending on the context in which the term is used.

The 5G network100may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time.

The UEs115are dispersed throughout the wireless network100, and each UE may be stationary or mobile. A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, UEs that do not include UICCs may also be referred to as internet of everything (IoE) or internet of things (IoT) devices. UEs115a-115dare examples of mobile smart phone-type devices accessing 5G network100A UE may also be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. UEs115e-115kare examples of various machines configured for communication that access 5G network100. A UE may be able to communicate with any type of the base stations, whether macro base station, small cell, or the like. InFIG. 1, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE and a serving base station, which is a base station designated to serve the UE on the downlink and/or uplink, or desired transmission between base stations, and backhaul transmissions between base stations.

5B network100may further support operations in NR-unlicensed (NR-U) spectrum, in which access to a shared communication channel is obtained after successfully performing a listen before talk. A base station, such as base station105a, may schedule transmission of a plurality of decoding candidates for UEs, such as UE115aand115b, during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-control resource set (CORESET) of a CORESET allocated to the transmission opportunity. Base station105amay uniformly distribute the plurality of decoding candidates for a served UE into the CORESET. Base station105amay detect at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs and modify transmission of the at least one decoding candidate in response to detecting the overlapping portion.

FIG. 2shows a block diagram of a design of a base station105and a UE115, which may be one of the base station and one of the UEs inFIG. 1. At the base station105, a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor220may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor220may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor230may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODS)232athrough232t. Each modulator232may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator232may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators232athrough232tmay be transmitted via the antennas234athrough234t, respectively.

At the UE115, the antennas252athrough252rmay receive the downlink signals from the base station105and may provide received signals to the demodulators (DEMODs)254athrough254r, respectively. Each demodulator254may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator254may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector256may obtain received symbols from all the demodulators254athrough254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor258may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE115to a data sink260, and provide decoded control information to a controller/processor280.

On the uplink, at the UE115, a transmit processor264may receive and process data (e.g., for the PUSCH) from a data source262and control information (e.g., for the PUCCH) from the controller/processor280. The transmit processor264may also generate reference symbols for a reference signal. The symbols from the transmit processor264may be precoded by a TX MIMO processor266if applicable, further processed by the modulators254athrough254r(e.g., for SC-FDM, etc.), and transmitted to the base station105. At the base station105, the uplink signals from the UE115may be received by the antennas234, processed by the demodulators232, detected by a MIMO detector236if applicable, and further processed by a receive processor238to obtain decoded data and control information sent by the UE115. The processor238may provide the decoded data to a data sink239and the decoded control information to the controller/processor240.

The controllers/processors240and280may direct the operation at the base station105and the UE115, respectively. The controller/processor240and/or other processors and modules at the base station105may perform or direct the execution of various processes for the techniques described herein. The controllers/processor280and/or other processors and modules at the UE115may also perform or direct the execution of the functional blocks illustrated inFIGS. 5A, 5B, and 7, and/or other processes for the techniques described herein. The memories242and282may store data and program codes for the base station105and the UE115, respectively. A scheduler244may schedule UEs for data transmission on the downlink and/or uplink.

Wireless communications systems operated by different network operating entities (e.g., network operators) may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (e.g., time) may be partitioned and allocated to the different network operating entities for certain types of communication.

For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In the 5G network100, base stations105and UEs115may be operated by the same or different network operating entities. In some examples, an individual base station105or UE115may be operated by more than one network operating entity. In other examples, each base station105and UE115may be operated by a single network operating entity. Requiring each base station105and UE115of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

FIG. 3illustrates an example of a timing diagram300for coordinated resource partitioning. The timing diagram300includes a superframe305, which may represent a fixed duration of time (e.g., 20 ms). The superframe305may be repeated for a given communication session and may be used by a wireless system such as 5G network100described with reference toFIG. 1. The superframe305may be divided into intervals such as an acquisition interval (A-INT)310and an arbitration interval315. As described in more detail below, the A-INT310and arbitration interval315may be subdivided into sub-intervals, designated for certain resource types, and allocated to different network operating entities to facilitate coordinated communications between the different network operating entities. For example, the arbitration interval315may be divided into a plurality of sub-intervals320. Also, the superframe305may be further divided into a plurality of subframes325with a fixed duration (e.g., 1 ms). While timing diagram300illustrates three different network operating entities (e.g., Operator A, Operator B, Operator C), the number of network operating entities using the superframe305for coordinated communications may be greater than or fewer than the number illustrated in timing diagram300.

The A-INT310may be a dedicated interval of the superframe305that is reserved for exclusive communications by the network operating entities. In some examples, each network operating entity may be allocated certain resources within the A-INT310for exclusive communications. For example, resources330-amay be reserved for exclusive communications by Operator A, such as through base station105a, resources330-bmay be reserved for exclusive communications by Operator B, such as through base station105b, and resources330-cmay be reserved for exclusive communications by Operator C, such as through base station105c. Since the resources330-aare reserved for exclusive communications by Operator A, neither Operator B nor Operator C can communicate during resources330-a, even if Operator A chooses not to communicate during those resources. That is, access to exclusive resources is limited to the designated network operator. Similar restrictions apply to resources330-bfor Operator B and resources330-cfor Operator C. The wireless nodes of Operator A (e.g, UEs115or base stations105) may communicate any information desired during their exclusive resources330-a, such as control information or data.

When communicating over an exclusive resource, a network operating entity does not need to perform any medium sensing procedures (e.g., listen-before-talk (LBT) or clear channel assessment (CCA)) because the network operating entity knows that the resources are reserved. Because only the designated network operating entity may communicate over exclusive resources, there may be a reduced likelihood of interfering communications as compared to relying on medium sensing techniques alone (e.g., no hidden node problem). In some examples, the A-INT310is used to transmit control information, such as synchronization signals (e.g., SYNC signals), system information (e.g., system information blocks (SIBs)), paging information (e.g., physical broadcast channel (PBCH) messages), or random access information (e.g., random access channel (RACH) signals). In some examples, all of the wireless nodes associated with a network operating entity may transmit at the same time during their exclusive resources.

In some examples, resources may be classified as prioritized for certain network operating entities. Resources that are assigned with priority for a certain network operating entity may be referred to as a guaranteed interval (G-INT) for that network operating entity. The interval of resources used by the network operating entity during the G-INT may be referred to as a prioritized sub-interval. For example, resources335-amay be prioritized for use by Operator A and may therefore be referred to as a G-INT for Operator A (e.g., G-INT-OpA). Similarly, resources335-bmay be prioritized for Operator B (e.g., G-INT-OpB), resources335-c(e.g., G-INT-OpC) may be prioritized for Operator C, resources335-dmay be prioritized for Operator A, resources335-emay be prioritized for Operator B, and resources335-fmay be prioritized for Operator C.

The various G-INT resources illustrated in NG.3appear to be staggered to illustrate their association with their respective network operating entities, but these resources may all be on the same frequency bandwidth. Thus, if viewed along a time-frequency grid, the G-INT resources may appear as a contiguous line within the superframe305. This partitioning of data may be an example of time division multiplexing (TDM). Also, when resources appear in the same sub-interval (e.g., resources340-aand resources335-b), these resources represent the same time resources with respect to the superframe305(e.g., the resources occupy the same sub-interval320), but the resources are separately designated to illustrate that the same time resources can be classified differently for different operators.

When resources are assigned with priority for a certain network operating entity (e.g., a G-INT), that network operating entity may communicate using those resources without having to wait or perform any medium sensing procedures (e.g., LBT or CCA). For example, the wireless nodes of Operator A are free to communicate any data or control information during resources335-awithout interference from the wireless nodes of Operator B or Operator C.

A network operating entity may additionally signal to another operator that it intends to use a particular G-INT. For example, referring to resources335-a, Operator A may signal to Operator B and Operator C that it intends to use resources335-a. Such signaling may be referred to as an activity indication. Moreover, since Operator A has priority over resources335-a, Operator A may be considered as a higher priority operator than both Operator B and Operator C. However, as discussed above, Operator A does not have to send signaling to the other network operating entities to ensure interference-free transmission during resources335-abecause the resources335-aare assigned with priority to Operator A.

Similarly, a network operating entity may signal to another network operating entity that it intends not to use a particular (i-INT. This signaling may also be referred to as an activity indication. For example, referring to resources335-b, Operator B may signal to Operator A and Operator C that it intends not to use the resources335-bfor communication, even though the resources are assigned with priority to Operator B. With reference to resources335-b, Operator B may be considered a higher priority network operating entity than. Operator A and Operator C. In such cases, Operators A and C may attempt to use resources of sub-interval320on an opportunistic basis. Thus, from the perspective of Operator A, the sub-interval320that contains resources335-bmay be considered an opportunistic interval (O-INT) for Operator A (e.g., O-INT-OpA). For illustrative purposes, resources340-amay represent the O-INT for Operator A. Also, from the perspective of Operator C, the same sub-interval320may represent an O-INT for Operator C with corresponding resources340-b. Resources340-a,335-b, and340-ball represent the same time resources (e.g., a particular sub-interval320), but are identified separately to signify that the same resources may be considered as a G-INT for some network operating entities and yet as an O-INT for others.

To utilize resources on an opportunistic basis, Operator A and Operator C may perform medium-sensing procedures to check for communications on a particular channel before transmitting data. For example, if Operator B decides not to use resources335-b(e.g., G-INT-OpB), then Operator A may use those same resources (e.g., represented by resources340-a) by first checking the channel for interference (e.g., LBT) and then transmitting data if the channel was determined to be clear. Similarly, if Operator C wanted to access resources on an opportunistic basis during sub-interval320(e.g., use an O-INT represented by resources340-b) in response to an indication that Operator B was not going to use its (i-INT (e.g., resources335-b), Operator C may perform a medium sensing procedure and access the resources if available. In some cases, two operators (e.g., Operator A and Operator C) may attempt to access the same resources, in which case the operators may employ contention-based procedures to avoid interfering communications. The operators may also have sub-priorities assigned to them designed to determine which operator may gain access to resources if more than operator is attempting access simultaneously. For example, Operator A may have priority over Operator C during sub-interval320when Operator B is not using resources335-b(e.g., G-INT-OpB). It is noted that in another sub-interval (not shown) Operator C may have priority over Operator A when Operator B is not using its G-INT.

In some examples, a network operating entity may intend not to use a particular G-INT assigned to it, but may not send out an activity indication that conveys the intent not to use the resources. In such cases, for a particular sub-interval320, lower priority operating entities may be configured to monitor the channel to determine whether a higher priority operating entity is using the resources. If a lower priority operating entity determines through LBT or similar method that a higher priority operating entity is not going to use its G-INT resources, then the lower priority operating entities may attempt to access the resources on an opportunistic basis as described above.

In some examples, access to a G-INT or G-INT may be preceded by a reservation signal (e.g., request-to-send (RTS)/clear-to-send (CTS)), and the contention window (CW) may be randomly chosen between one and the total number of operating entities.

In some examples, an operating entity may employ or be compatible with coordinated multipoint (CoMP) communications. For example an operating entity may employ CoMP and dynamic time division duplex (TDD) in a G-INT and opportunistic CoMP in an O-INT as needed.

In the example illustrated inFIG. 3, each sub-interval320includes a G-INT for one of Operator A, B, or C. However, in some cases, one or more sub-intervals320may include resources that are neither reserved for exclusive use nor reserved for prioritized use (e.g., unassigned resources). Such unassigned resources may be considered an O-INT for any network operating entity, and may be accessed on an opportunistic basis as described above.

In some examples, each subframe325may contain 14 symbols (e.g., 250-μs for 60 kHz tone spacing). These subframes325may be standalone, self-contained Interval-Cs (ITCs) or the subframes325may be a part of a long ITC. An ITC may be a self-contained transmission starting with a downlink transmission and ending with an uplink transmission. In some embodiments, an ITC may contain one or more subframes325operating contiguously upon medium occupation. In some cases, there may be a maximum of eight network operators in an A-INT310(e.g., with duration of 2 ms) assuming a 250-μs transmission opportunity.

Although three operators are illustrated inFIG. 3, it should be understood that fewer or more network operating entities may be configured to operate in a coordinated manner as described above. In some cases, the location of the G-INT, O-INT, or A-INT within the superframe305for each operator is determined autonomously based on the number of network operating entities active in a system. For example, if there is only one network operating entity, each sub-interval320may be occupied by a G-INT for that single network operating entity, or the sub-intervals320may alternate between G-INTs for that network operating entity and O-INTs to allow other network operating entities to enter. If there are two network operating entities, the sub-intervals320may′ alternate between G-INTs for the first network operating entity and G-INTs for the second network operating entity. If there are three network operating entities, the G-INT and O-INTs for each network operating entity may be designed as illustrated inFIG. 3. If there are four network operating entities, the first four sub-intervals320may include consecutive G-INTs for the four network operating entities and the remaining two sub-intervals320may contain O-INTs. Similarly, if there are five network operating entities, the first five sub-intervals320may contain consecutive G-INTs for the five network operating entities and the remaining sub-interval320may contain an O-INT. If there are six network operating entities, all six sub-intervals320may include consecutive G-INTs for each network operating entity. It should be understood that these examples are for illustrative purposes only and that other autonomously determined interval allocations may be used.

It should be understood that the coordination framework described with reference toFIG. 3is for illustration purposes only. For example, the duration of the superframe305may be more or less than 20 ms. Also, the number, duration, and location of sub-intervals320and subframes325may differ from the configuration illustrated. Also, the types of resource designations (e.g., exclusive, prioritized, unassigned) may differ or include more or less sub-designations.

5G NR operations, including NR unlicensed (NR-U) installations, may be configured with wideband system bandwidths, for example in multiples of 20 MHz (e.g., 20 MHz, 40 MHz, 60 MHz, 100 MHz, etc.). However, 5G NR operations may also compete for access to shared channels with other radio access technologies, such as WiFi, which operates in a 20 MHz channel access manner. Thus, a typical NR operating mode may use a subband access procedure to establish communication with the shared communication channel, which may include the entire system bandwidth or a portion of the allocated bandwidth (e.g., a bandwidth part (BWP)).

In operation, the active BWP is divided into multiple subbands. In NR-U operations, because WiFi may compete for channel access on a 20 MHz level, an NR-U network entity (e.g., gNB, base station, UE, etc.) would perform a listen before talk (LBT) operation on each subband to determine whether it may access and use the subband for communications. Thus, an NR-U network entity dynamically determines which of the allocated subbands are accessible and which are not. The accessible subbands, in which a successful LBT is performed, may or may not be continuous, but the UE does not know in advance exactly which subband(s) may be used. It may be beneficial to thoughtfully consider design of the control resource sets (CORESETs) for the candidate subbands when accessibility is unknown in advance. Because a UE does not know in advance which subbands will pass LBT, CORESET design should be capable to handle any combination of eventual subband usage.

FIG. 4Ais a block diagram illustrating a base station105and UE115in communications40over NR-U operations implementing a prior CORESET design solution.FIG. 4Aillustrates a previously proposed solution in which BWP400may be accessed via four subbands, subbands 0-3. Multiple CORESETs, CORESETs 0-3, are configured and allocated to each of subband 0-3, with further configuration of the search space sets, search spaces 0-9, in each CORESET.

Difficulties with this multi-CORESET solution may arise due to the limited number of CORESETs and search space sets currently supported in NR configurations. Currently, NR supports a maximum of three CORESETs with 10 search space sets per BWP, with four BWPs per cell. For a BWP of 80 MHz and LBT subband of 20 MHz, there are four available subbands per BWP, there would be four associated CORESETs for each BWP (one for each subband of the BWP), which already exceeds the supported maximum number of CORESETs.

FIG. 4Bis a block diagram illustrating a base station105and UE115in communications41over NR-U operations implementing another previously suggested CORESET design solution.

According to the previously proposed solution illustrated inFIG. 4B, a single, wideband CORESET42is configured to be hashed or distributed in portions over each subband, subbands 0-3, of BWP401. The portions of wideband CORESET42associated with each subband may be referred to as a sub-CORESETs, sub-CORESET41. Base station105may then distribute transmission of a decoding candidate402(e.g., downlink control channel, PDCCH, etc.) across each of subband 0-3 within the search space set of the associated sub-CORESET41. As base station105performs LBT procedures for each of subband 0-3, for any transmissions, including transmissions of the decoding candidate part402, falling within a subband in which the LBT fails, base station105would puncture the corresponding resource element groups (REGs) of sub-CORESET41that fall within the inaccessible subbands. The CORESET design solution illustrated inFIG. 4Bwould include interleaved component carrier element (CCE)-to-REG mapping and use a large enough aggregation level to have enough CCEs to be distributed to all of subbands 0-3 (before puncturing).

It should be noted that all of subbands 0-3 in BWP401would not necessarily have a corresponding CORESET42/sub-CORESET41configured. There would be a service or throughput trade-off, such that, when fewer subbands are configured with sub-CORESET41, UE115could not be served when those subbands pass LBT.

Difficulties with the features illustrated inFIG. 4Bmay arise with the decoding performance for set of decoding candidates402(e.g., PDCCH). For wideband CORESET42configured for distribution across all of subbands 0-3 and having any REGs falling within inaccessible subbands punctured, the decoding performance by UE115of set of decoding candidates402may fall because the punctured parts would be unknown.

It should further be noted that, in order to ensure sufficient REGs for even distribution in all of the distributed sub-CORESETs, the aggregation level may be higher. Therefore, decoding performance with a large aggregation level but heavy puncturing may not be optimized for Polar code design.

Aspects of the present disclosure include design of a single CORESET that may be distributed over multiple/all subbands of a given BWP, with one sub-CORESET assigned per subband. Each sub-CORESET may be a multiple of 6RBs wide with localized CCE-to-REG mapping and uniform hashing or distribution of a set of decoding candidates in the CCE space. If the sub-CORESET size is selected properly, with low enough aggregation level, the decoding candidates should not span sub-CORESET/subband boundaries. However, this is not guaranteed, and, especially with higher symbol-size CORESETs, one or more of the distributed decoding candidates may span the boundary between multiple sub-CORESETs. The various aspects of the present disclosure are directed to modifying transmission of the set of decoding candidates when one or more of the candidates overlaps the boundary of multiple sub-CORESETs. For such decoding candidates that span the boundary of multiple sub-CORESETs, a base station may either remove the decoding candidate from the set of candidates, thus, treating it as invalid and not using it; dither the decoding candidate to shift it to the next location fully contained within a sub-CORESET; or continue transmission of the decoding candidate but with puncturing of the portion located in the inaccessible subband, which may cause the receiver processing to become more complex.

It should be noted that, in all such optional cases, the UE should know about the existence of the subbands or sub-CORESETs.

FIG. 5Ais a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to base station105as illustrated inFIG. 9.FIG. 9is a block diagram illustrating base station105configured according to one aspect of the present disclosure. Base station105includes the structure, hardware, and components as illustrated for base station105ofFIG. 2. For example, base station105includes controller/processor240, which operates to execute logic or computer instructions stored in memory242, as well as controlling the components of base station105that provide the features and functionality of base station105. Base station105, under control of controller/processor240, transmits and receives signals via wireless radios900a-tand antennas234a-t. Wireless radios900a-tincludes various components and hardware, as illustrated inFIG. 2for base station105, including modulator/demodulators232a-t, MIMO detector236, receive processor238, transmit processor220, and TX MIMO processor230.

At block500, a base station schedules transmission of a plurality of decoding candidates during a transmission opportunity on a shared communication channel, wherein each subband of a plurality of subbands of the transmission opportunity is assigned a sub-CORESET of a wideband CORESET allocated to the BWP of the transmission opportunity. For example, base station105, under control of controller/processor240, executes decoding candidate scheduler901, stored in memory242. The execution of decoding candidate scheduler901provides for base station105to configure a set of decoding candidates for distribution across search spaces of the CORESET.

At block501, the base station uniformly distributes the plurality of decoding candidates for a served UE into the CORESET. Within the execution environment of decoding candidate scheduler901further provides for uniform distribution of the plurality of decoding candidates in the CORESET.

At block502, the base station detects at least one decoding candidate of the plurality of decoding candidates spanning a boundary between two or more sub-CORESETs. Base station105, under control of controller/processor240determines the location of each of the distributed decoding candidates relative to the layout of the subbands and assigned sub-CORESETs and may identify when a decoding candidate overlaps two subbands and two sub-CORESETs.

At block503, the base station modifies the transmission of the at least one decoding candidate portion in response to the detecting. For example, base station105, under control of controller/processor240executes overlap logic903, stored in memory242. The execution environment of overlap logic903provides for addressing the overlapping decoding candidates. In a first optional solution, base station105may simply remove the decoding candidate that spans the boundary between sub-CORESETs from the plurality of decoding candidates. A second optional solution may provide for base station105to shift the transmission location of the overlapping decoding candidate to a next available location wholly within a sub-CORESET. A third optional solution provides for base station105to continue the scheduled transmission of the overlapping decoding candidate, but, where one of the subbands associated with the sub-CORESETs across which boundary the decoding candidate spans fails LBT and is inaccessible, transmission of that part of the decoding candidate is punctured.

FIG. 5Bis a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to UE115as illustrated inFIG. 10.FIG. 10is a block diagram illustrating UE115configured according to one aspect of the present disclosure. UE115includes the structure, hardware, and components as illustrated for UE115ofFIG. 2. For example, UE115includes controller/processor280, which operates to execute logic or computer instructions stored in memory282, as well as controlling the components of UE115that provide the features and functionality of UE115.

UE115, under control of controller/processor280, transmits and receives signals via wireless radios1000a-rand antennas252a-r. Wireless radios1000a-rincludes various components and hardware, as illustrated inFIG. 2for UE115, including modulator/demodulators254a-r, MIMO detector256, receive processor258, transmit processor264, and TX MIMO processor266.

At block504, a UE obtains a set of decoding candidates. For example, UE115obtains the set of decoding candidates including potential locations within the search spaces of the sub-CORESETs in each subband. UE115may obtain this information from system broadcast, from semi-static signaling, dynamic signaling, or the like, and stored at decoding candidate set1001, in memory282. It may also obtain the information from device information pre-programmed into decoding candidate set1001by a device manufacturer.

At block504, the UE performs one or more blind decoding procedures of one or more search spaces of a sub-CORESET associated with each subband of a plurality of subbands of a transmission opportunity on a shared communication channel, wherein the one or more blind decoding procedures are performed to detect at least one of the set of decoding candidates. For example, UE115, under control of controller/processor280, executes blind decoding logic1002. The execution environment of blind decoding logic1002allows for UE115to perform a certain number of blind decoding procedures to detect the set of decoding candidates among the search spaces.

The first optional solution is the simplest design. On the UE side, UE115may reuse the blind decoding process that would have been used on the dropped candidate for other search space sets. The second optional solution maintains the number of blind decodings without sacrificing scheduler flexibility, but additional rules would be introduced to perform the dithering or shifting. For example, if a decoding candidate portion is scheduled on the boundary, the base station may shift by 1 candidate location at the same aggregation level. The third optional solution may be simple for the transmitter, but more complex with the receiver processing. The receiver would attempt to identify the part of the decoding candidate portion not transmitted due to subband LBT failure, which could increase the number of blind decodings performed by UE115. A receiver, such as UE115, may be configured to use two or three hypotheses, as a part of the execution environment of blind decoding logic1002, in attempting to detect and decode a decoding candidate portion transmitted according to the third optional solution. Using a two-hypothesis approach, UE115may use two blind decoding processes: one for the assumption that the part of the decoding candidate portion was transmitted over subband A/sub-CORESET A; and another for the assumption that the part of the decoding candidate portion was transmitted over subband B/sub-CORESET B. Using the three-hypothesis approach, in addition to the two blind decoding procedures used for the first two hypotheses above, another blind decoding procedure would be used for the assumption that both parts of the decoding candidate portion are successfully transmitted over subband A/sub-CORESET A and subband B/sub-CORESET B. A UE, such as UE115, may also just try a single hypothesis approach by assuming both parts are transmitted but that may be associated with some performance loss as the punctured part would just add noise in the decoder.

FIG. 6is a block diagram illustrating a base station105and UE115configured according to one aspect of the present disclosure. Base station105and UE115engage in communications60over an NR-U network. The entire allocated BWP for communication60is divided into four subbands, subbands 0-3. A wideband CORESET 0 is defined for the BWP with individual sub-CORESET 0 allocated to each of subband 0-3. Transmission61illustrates the scheduled communications that base station105prepares for UE115, which includes distribution or hashing of a plurality of decoding candidates601-605. Each decoding candidate of transmission61, including decoding candidates601-605are uniformly distributed onto subbands 0-3. Optional scheduled communications600provide implementation of one of the optional solutions for handling a decoding candidate overlapping a boundary of multiple sub-CORESETs, such as decoding candidate603.

Upon detecting that decoding candidate603overlaps the boundary between subband 1 and subband 2, and, therefore, the boundary between sub-CORESET 0 assigned to subbands 1 and 2, base station105may modify the transmission of the decoding candidates601-605according to one of the optional solutions. According to the first optional solution, base station105removes decoding candidate603from the plurality of decoding candidates601-605for Opt 1 scheduled communication of optional scheduled communications600.

Alternatively, according to the second optional solution, when base station105detects decoding candidate603overlaps the boundary between subbands 1 and 2, it shifts the scheduled transmission of decoding candidate603to a next available location wholly within subband 2, as illustrated in Opt 2 scheduled communication of optional scheduled communications600.

Alternatively, according to the third optional solution, when base station105detects decoding candidate603overlaps the boundary between subbands 1 and 2, it continues with the scheduled transmission of decoding candidate603, but will transmit according to the accessibility of subbands 1 and 2. In a first example occasion, the LBT fails for subband 1 and passes for subband 2. In such a scenario, the part of decoding candidate603that lies within subband 1 is punctured, while the part in subband 2 is transmitted. In a second example occasion, the LBT passes for subband 1, but fails for subband 2. Conversely, the part of decoding candidate603located in subband 1 is transmitted while the part in subband 2 is punctured. In a third example occasion, LBT for both subbands 1 and 2 pass, in which case the part of decoding candidate603in subband 1 is transmitted according to the assigned sub-CORESET 0 for subband 1 and the part of decoding candidate603in subband 2 is transmitted according to the assigned sub-CORESET 0 for subband 2.

In each such optional solution, the CORESET overhead is increased with higher decoding candidate monitoring complexity. Additional aspects of the present disclosure are directed to fast CORESET switching. Outside of the transmission opportunity (TXOP) or in the beginning slots in the TXOP, the default CORESET structure of sub-CORESETs assigned without LBT knowledge, as described above, may be used. For example, one such specific option may be used for the UE to monitor the start of TXOP (when common PDCCH is used to indicate the TXOP start). In addition, the specific optional solution described above may be used for scheduling in the first few slots in the TXOP. Inside the TXOP or at least within a few slots after the start of the TXOP, the UE may be configured with different CORESET configurations which can take the LBT outcome or channel accessibility into consideration. This allows potentially less overhead with the CORESET design and, thus, fewer decoding candidate monitoring occasions for the UE. In other words, given a fixed PDCCH processing capability (e.g., a fixed, maximum number of blind decoding processes that the UE can conduct), the UE can use those finite capabilities more efficiently and allocate the computational power to the accessible subbands.

FIG. 7is a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to UE115as illustrated inFIG. 10.

At block700, a UE obtains a CORESET configuration including CORESETs associated with multiple possible LBT outcomes. For example, UE115may receive a CORESET configuration signal from a serving base station via antennas252a-rand wireless radios1000a-r. The set of CORESETs within the CORESET configuration along with associated subband combinations are stored at CORESET configuration1004, in memory282.

At block701, the UE monitors for a plurality of decoding candidates using a default sub-CORESET at the start of a transmission opportunity. For example, UE115, under control of controller/processor280, accesses the default CORESET information at default CORESET1003, in memory282. The default CORESET information identifies the sub-CORESETs assigned to each subband in the active BWP. Using this default CORESET information, UE115may monitor relevant search space for the plurality of decoding candidates.

At block702, the UE receives an indication associated with a new CORESET for subsequent slots in the transmission opportunity. For example, UE115receives a message from a serving base station that indicates the accessible subbands of the allocated BWP. UE115may store such accessibility information at subband usage1005, in memory282.

At block703, the UE selects a new CORESET for decoding candidate monitoring in the subsequent slots. In response to this combination of known accessible subbands, UE115may select a corresponding new CORESET in CORESET configuration1004. UE115uses the new CORESET for performing blind decoding for decoding candidates according to the new CORESET.

At block704, the UE switches back to a default sub-CORESET at the end of the transmission opportunity. As UE115detects the end of the transmission opportunity, it returns to operations using the default CORESET, stored at default CORESET1003.

FIG. 8is a block diagram illustrating a base station105and UE115configured according to one aspect of the present disclosure. Base station105and UE115are engaged in communication stream80over an NR-U network. The communication slots of communication stream80includes mini-slot communication capabilities within each slot. Prior to TXOP801, base station105schedules transmissions using the default CORESET800that does not account for LBT knowledge. UE115monitors for decoding candidate transmissions in each mini-slot according to the default sub-CORESET assigned to the mini-slot from default CORESET800. At some point within region802, UE115receives a CORESET configuration message from base station105. The CORESET configuration message includes a number of different CORESET configurations associated with various possible LBT outcomes. Thus, the CORESET configuration message includes different possible combinations of CORESETs with different combinations of accessible subbands.

UE115may thus be configured with multiple CORESET configurations, each corresponding to one or more potential LBT outcomes. For example, besides default CORESET800for outside or the beginning of TXOP801, UE115may be configured with other CORESETs, each one corresponding to one or more possible LBT outcomes. The extreme case may be one CORESET configuration for each LBT outcome. For example, for four subbands with arbitrary LBT possibility and all subband combinations allowed for transmission base station105may configure up to 15 CORESET configurations within the CORESET configuration message. For four subbands case where transmission is allowed only for continuous subbands that pass LBT, the base station105may configure up to 10 CORESET configurations corresponding to the following allowed subband combinations {{0}, {1}, {2}, {3}, {0,1}, {1,2}, {2,3}, {0,1,2}, {1,2,3}, {0,1,2,3}} selected by gNB for transmission. A more general case may include configuration of one CORESET for a set of LBT outcomes (e.g., Subband 0/1/2/3 LBP pass and subband 0/1 LBT pass can share the same CORESET configuration with CORESET in subband 0/1). Each CORESET may span the subbands or set of subbands that have passed their LBT.

It should be noted that, while illustrated as being obtained by UE115at region802, the various aspects of the present disclosure are not limited only to receiving such CORESET configuration message in the illustrated location. In fact, UE115may receive such configuration message semi-statically in RRC signaling or in system information broadcasts from base station105at any time during communication stream80prior to the trigger to switch CORESETs based on knowledge of LBT outcomes.

At803, TXOP801starts. During the first few mini-slots of TXOP801, UE115may continue to perform monitoring for decoding candidates according to the default sub-CORESET without knowledge of any LBT outcomes or in which the CORESET selection is not influenced by LBT outcomes. At region804, UE115may receive an indication associated with a new CORESET for UE115to use in subsequent slots of TXOP801. Such an indication may be received from base station105via a cell-specific signal or a UE-specific signal.

In a first optional aspect, a cell-specific CORESET switch may be used. For example, information identifying the start (803) of TXOP801may also include an indication of which subbands have passed their LBT. Such an indication may comprise a common control signals, such as common PDCCH (CPDCCH), system broadcast information (MIB or SIB), or specific RRC signaling. Once UE115detects this indication signal, UE115may select and switch to a different CORESET configuration, identified in the CORESET configuration message according to the LBT outcome information included in the indication. The indication signal may also include timing information that informs UE115when, after receipt of the indication at804, UE115should switch to the new CORESET. The timing information ensures that both UE115and base station105are using the same CORESET at the same time.

It should be noted that, in additional or alternative aspects of the present disclosure, the indication signal may specifically identify the CORESET for UE115to switch to upon detecting which subbands have passed LBT.

In a second optional aspect, a UE-specific indication may be signaled, which provides a more dynamic signaling, such as via layer 1 (L1) signaling or downlink control information (DCI)-based signaling, identifying a CORESET switching signal. Within TXOP801, base station105can send UE-specific L1 signaling to switch UE115from the default CORESET800configuration to the new CORESET805that includes LBT knowledge. As with the first optional aspect, timing information may be included in the CORESET switching signals or provided in separate L1 or RRC signaling. By switching to new CORESET805with LBT knowledge, UE115does not have to perform decoding candidate monitoring on subbands that did not pass LBT and on each mini-slot, such as mini-slot806. Prior to the COT start, since gNB did not have access to the channel. it was desirable to allow gNB to start transmission at any mini-slot boundary so it does not have to wait for too long once it finds the channel is free. This however comes at cost of UE power since UE monitors for PDCH at every mini-slot. However, within the COT since gNB has the medium already, it can switch to a lower PDCCH monitoring period (monitor at slot level instead of mini-slot level) thereby saving UE power. The processing power of UE115may, therefore, be conserved for actual decoding candidate transmissions.

At the end of TXOP801, UE115would automatically switch back to default CORESET800without LBT knowledge. With the beginning of a new TXOP, the LBT outcomes are again unknown for each subband allocated for communication stream80between base station105and UE115. Accordingly, UE115would revert to monitoring based on the default sub-CORESET design applied for each slot or mini-slot of the next TXOP.