Patent Description:
In some examples, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation or <NUM> network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., a new radio base station (NR BS), a new radio node-B (NR NB), a network node, <NUM> NB, eNB, etc.). A base station or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) as well as support beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to increase, there exists a desire for further improvements in NR technology.

Document <NPL>, discloses forming large aggregation level search space candidate using CCEs across OFDM symbols by concatenating smaller aggregation level search space candidates aligned in frequency.

Aspects of the present invention are set out in the accompanying claims. Certain aspects provide a method for wireless communication by a network node such as a gNB. The method generally includes generating a physical downlink control channel (PDCCH) message for transmission at an aggregation level (AL), wherein the AL comprises a union of control channel elements (CCEs) in one or more search spaces within a control resource set (CORESET) and transmitting the PDCCH message to a user equipment (UE) at the AL.

Certain aspects provide a method for wireless communication by a user equipment (UE). The method generally includes receiving a physical downlink control channel (PDCCH) message at an aggregation level (AL), wherein the AL comprises a union of control channel elements (CCEs) in one or more search spaces within a control resource set (CORESET) and decoding the PDCCH message at the AL.

To the accomplishment of the foregoing and related ends, the one or more aspects include the features hereinafter fully described and particularly pointed out in the claims.

It is contemplated that elements described in one aspect may be beneficially utilized on other aspects without specific recitation. Aspects generally include methods, apparatus, systems, computer program products, computer-readable medium, and processing systems, as substantially described herein with reference to and as illustrated by the accompanying drawings.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for NR (new radio access technology or <NUM> technology).

NR may support various wireless communication services, such as Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM> or beyond), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low latency communications (URLLC).

To carry a PDCCH, multiple Control Channel Elements (CCEs) are used. An aggregation level (AL) defines the number of CCEs used for PDCCH transmission to a UE. Some wireless communication standards may define ALs for transmitting a PDCCH. As an example, NR Release-<NUM> defines AL <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

There may be situations in which it may be desirable for a control message (e.g., NR physical downlink control channel (PDCCH) message) to be transmitted to a UE using an AL that is different than an AL defined in a standard. As an example, in URLLC, higher, different, or additional aggregation levels may be desirable in an effort to achieve higher reliability for PDCCH.

According to aspects of the present disclosure, new or additional ALs may be defined, outside of the ALs defined in a standard. As will be described in more detail herein, the ALs may be based on (time-frequency) resource availability and/or UE processing capability. The new AL includes a union of CCEs in one or more search spaces within a control resource set (CORESET) assigned to a UE. Additional aspects are provided which relate to the introduction of new ALs. These aspects include demodulation reference signal design, RRC configuration of the new AL, a type of downlink control information (DCI) format used with the new ALs, and ensuring a UE refrains from performing a number of blind decodes that exceeds a predefined threshold. The new ALs advantageously allow a UE to use additional CCEs (e.g., CCEs that may not have been previously used for PDCCH transmission) for reception of PDCCH subject to resource availability and processing capability. In this manner, resources may be efficiently used and the UE may have achieve a higher reliability for receiving a PDCCH.

It should be understood that any aspect of the disclosure described herein may be embodied by one or more elements of a claim.

"LTE" refers generally to LTE, LTE-Advanced (LTE-A), LTE in an unlicensed spectrum (LTE-whitespace), etc. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies.

<FIG> illustrates an example wireless network <NUM>, such as a new radio (NR) or <NUM> network, in which aspects of the present disclosure may be performed.

A network entity such as a BS <NUM> may transmit a PDCCH using an AL as described herein (e.g., not defined in a current version of a standard) and a UE <NUM> may receive and decode the PDCCH, by monitoring a search space for the AL based on a union of control channel elements (CCEs) for other AL search spaces, as described herein.

As illustrated in <FIG>, the wireless network <NUM> may include a number of BSs <NUM> and other network entities. A BS may be a station that communicates with UEs. Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term "cell" and eNB, Node B, <NUM> NB, AP, NR BS, NR BS, gNB, or TRP may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in the wireless network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

A network controller <NUM> may be coupled to a set of BSs and provide coordination and control for these BSs. The BSs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a healthcare device, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, virtual reality goggles, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, a robot, a drone, industrial manufacturing equipment, a positioning device (e.g., GPS, Beidou, terrestrial), or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices, which may include remote devices that may communicate with a base station, another remote device, or some other entity. Machine type communications (MTC) may refer to communication involving at least one remote device on at least one end of the communication and may include forms of data communication which involve one or more entities that do not necessarily need human interaction. MTC UEs may include UEs that are capable of MTC communications with MTC servers and/or other MTC devices through Public Land Mobile Networks (PLMN), for example. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, cameras, location tags, etc., that may communicate with a BS, another device (e.g., remote device), or some other entity. MTC UEs, as well as other UEs, may be implemented as Internet-of-Things (IoT) devices, e.g., narrowband IoT (NB-IoT) devices.

For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a 'resource block') may be <NUM> subcarriers (or <NUM>). Consequently, the nominal FFT size may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM> (e.g., <NUM> resource blocks), and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using time division duplex (TDD). A single component carrier bandwidth of <NUM> may be supported. NR resource blocks may span <NUM> sub-carriers with a sub-carrier bandwidth of <NUM> over a <NUM> duration. Each radio frame may consist of <NUM> half frames, each half frame consisting of <NUM> subframes, with a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (e.g., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. UL and DL subframes for NR may be as described in more detail below with respect to <FIG>. Alternatively, NR may support a different air interface, other than an OFDM-based. NR networks may include entities such CUs and/or DUs.

As noted above, a RAN may include a CU and DUs. A NR BS (e.g., eNB, <NUM> Node B, Node B, transmission reception point (TRP), access point (AP)) may correspond to one or multiple BSs. NR cells may be configured as access cell (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) may configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases DCells may not transmit synchronization signals-in some case cases DCells may transmit SS. NR BSs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine NR BSs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

<FIG> illustrates example components of the BS <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. As described above, the BS may include a TRP. One or more components of the BS <NUM> and UE <NUM> may be used to practice aspects of the present disclosure. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to <FIG> and <FIG>.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), etc. The data may be for the Physical Downlink Shared Channel (PDSCH), etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. For example, the TX MIMO processor <NUM> may perform certain aspects described herein for RS multiplexing.

For example, MIMO detector <NUM> may provide detected RS transmitted using techniques described herein. According to one or more cases, CoMP aspects may include providing the antennas, as well as some Tx/Rx functionalities, such that they reside in distributed units. For example, some Tx/Rx processings may be done in the central unit, while other processing may be done at the distributed units. For example, in accordance with one or more aspects as shown in the diagram, the BS mod/demod <NUM> may be in the distributed units.

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of the functional blocks illustrated in <FIG> and/or other processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct, e.g., the execution of the functional blocks illustrated in <FIG> and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the BS <NUM> and the UE <NUM>, respectively.

The DL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> may sometimes be referred to as an UL burst, a common UL burst, and/or various other suitable terms. The common UL portion <NUM> may include feedback information corresponding to various other portions of the DL-centric subframe. For example, the common UL portion <NUM> may include feedback information corresponding to the control portion <NUM>. Non-limiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ indicator, and/or various other suitable types of information. The common UL portion <NUM> may include additional or alternative information, such as information pertaining to random access channel (RACH) procedures, scheduling requests (SRs), and various other suitable types of information. As illustrated in <FIG>, the end of the DL data portion <NUM> may be separated in time from the beginning of the common UL portion <NUM>. One of ordinary skill in the art will understand that the foregoing is merely one example of a DL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

<FIG> is a diagram <NUM> showing an example of an UL-centric subframe. The UL -centric subframe may include a control portion <NUM>. The control portion <NUM> may exist in the initial or beginning portion of the UL-centric subframe. The control portion <NUM> in <FIG> may be similar to the control portion <NUM> described above with reference to <FIG>. The UL-centric subframe may also include an UL data portion <NUM>. The UL data portion <NUM> may sometimes be referred to as the payload of the UL-centric subframe. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (e.g., UE) to the scheduling entity (e.g., UE or BS). In some configurations, the control portion <NUM> may be a physical DL control channel (PDCCH).

As illustrated in <FIG>, the end of the control portion <NUM> may be separated in time from the beginning of the UL data portion <NUM>. The UL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> in <FIG> may be similar to the common UL portion <NUM> described above with reference to <FIG>. The common UL portion <NUM> may additional or alternative include information pertaining to channel quality indicator (CQI), sounding reference signals (SRSs), and various other suitable types of information. One of ordinary skill in the art will understand that the foregoing is merely one example of an UL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

In communication systems operating according to new radio (NR) (e.g., <NUM>) standards, one or more control resource sets (CORESET) for transmission of PDCCHs may be supported. A CORESET may include one or more control resources (e.g., time and frequency resources) configured for conveying PDCCH. Within each CORESET, one or more search spaces (e.g., common search space, UE-specific search space, etc.) may be defined for a given UE. A CORESET may be defined in units of resource element groups (REGs). Each REG may include a fixed number (e.g., twelve, or some other number) of tones in one symbol period (e.g., a symbol period of an OFDM symbol), where one tone in one symbol period is referred to as a resource element (RE). A fixed number of REGs may be included in a control channel element (CCE) (e.g., a CCE may include six REGs, or some other number of REGs).

A NR-PDCCH may occupy one or more NR-CCEs. For NR-PDCCH, different numbers of NR-CCEs may form the resource for downlink control information (DCI). The number of NR-CCEs in a NR-PDCCH generally refers to the NR-PDCCH's aggregation (AL). The AL generally configures the coverage of DCI and the amount of resource used for the DCI. Multiple sets of NR-CCEs may be defined as search spaces for UEs. For example, for NR-PDCCH, one or more search spaces may be defined, where each search space includes a set of decoding candidates with one or more aggregation levels. Thus, a gNB may transmit a NR-PDCCH to a UE by transmitting the NR-PDCCH in a set of CCEs that is defined as a decoding candidate within a search space for the UE. Likewise, the UE may receive the NR-PDCCH by searching in search spaces for the UE and decoding the NR-PDCCH transmitted by the gNB.

As described above, a CORESET includes the set of potential resources that can be used for PDCCH transmission. In an example, a CORESET set may contain <NUM> CCEs, e.g., CCEs {<NUM>. The CCE indices are logical indices and a specific logical-to-physical mapping function conveys to the UE where to find CCE k.

One or more search spaces may exist within a UE's CORESET. For each UE, NR defines a common search space (CSS) and one or more UE-specific search spaces (USS). A CSS is used for control information that is to be sent to multiple UEs. A USS includes CCEs that are used to send information to a particular UE. For USSs, each search space is tied with one PDCCH AL. As an example, all PDCCH candidates of AL <NUM> form one search space. Search spaces may overlap. Accordingly, any portion of one or more USSs and the CSSs may have overlapping CCEs.

A UE performs channel estimation and demodulation for all CCEs in all configured search spaces for blind detection of a PDCCH. Due to UE hardware limitations, the UE may not be able to process all CCEs within the CORESET. UE processing capability refers to how many CCEs the UE is able to process (e.g., perform channel estimation) in a time slot or one PDCCH monitoring occasion based, at least in part, on hardware conditions. According to current wireless standard agreements, a network node ensures search spaces are within a UE's processing capability. If a search space is outside of the UE's processing capability, the UE is not required to decode the information contained in the resources.

As described herein, new AL(s) are designed and defined which allow a UE to use more CCEs, subject to resource (e.g., CCE) availability and UE processing capability. Advantageously, the new ALs allow a UE to use more, additional, and/or different CCEs for PDCCH transmission/reception in an effort to increase reliability for a UE receiving a PDCCH (e.g. as compared to only being able to use the pre-defined ALs). As will be described in more detail below, the new AL(s) may be formed based on a union of CCEs in one or more search spaces and/or may include all CCEs within the UE's processing capability within the UE's CORESET.

<FIG> illustrates an example <NUM> of a CORESET including multiple search spaces (SSs). Three search spaces are illustrated in the CORESET <NUM>. SS1 and SS2 may be USSs for a particular UE and SS3 may be a CSS. A search space, such as SS1, may include <NUM> PDCCH candidates. Each PDCCH candidate contains a number of CCEs. As illustrated, a portion of SS1, SS2, and SS3 overlap; however, the overlap of SSs may be more or less than illustrated in <FIG>.

In an example, a UE is configured with a CSS, USS1, USS2,. , USSK, where ALs for USSs are L_1<L_2<. In accordance with the present disclosure, a new AL is defined that includes the union of CCEs in one or more of the SSs within one CORESET. The new AL is defined by the union of CCEs in one or more search spaces, in part, due overlapping SSs, wherein one or more CCEs may be part of multiple SSs. As SSs may be overlapping, the union of CCEs, instead of the sum of CCEs is used to define or characterize the AL.

According to a first option, SSs are combined based on a scrambling ID. Each PDCCH has a scrambling sequence (the sequence is generated using one ID). The scrambling sequence is used to scramble the encoded PDCCH data and the demodulation reference signal (DMRS) of the PDCCH transmission. In NR, different scrambling IDs may be used for the CSS and the USSs. As multiple UEs receive the PDCCH in the CSS, an ID specific for a gNB may be used to scramble the PDCCH in the CSS. Because a USS is UE-specific, a UE-specific ID may be used for the scrambling of the PDCCH transmitted in the USS. Accordingly, a possibility exists where different scrambling IDs are used for transmitting the PDCCH in the CSS and the USS.

If the scrambling ID of USSs and CSS are the same, then all CCEs in the union of all SSs (CSS and USSs) may be combined to form an AL having one PDCCH decoding candidate. If the PDCCH transmitted in the CSS and USSs are scrambled by different IDs, then all CCEs in the union of all USSs may be combined to form one PDCCH decoding candidate and all CCEs in the CSS can be combined to form another PDCCH decoding candidate.

Thus, in one example, in accordance with the present invention, search spaces may be combined based on scrambling IDs to define a new AL. The AL will equal the size (e.g., number of CCEs) of the union of the CCEs in the SSs of the CORESET having a same scrambling ID for the PDCCH. USSs for a particular UE may use the same scrambling ID. If the CSS also uses that same scrambling ID as used in the USS, then the AL is the union of all CCEs in all SSs within the CORESET. If the USSs and the CSS use different scrambling IDs, then a first new (additional) AL is the number of CCEs in the CSS and another new (additional) AL is the union of CCEs in the USSs.

According to an aspect, instead of combining SS based on a scrambling ID, the SS may be combined based on the type of search space, e.g., whether the SS is a USS or a CSS. All CCEs in the union of the USSs may form an AL. All CCEs in the CSS may be used to form another AL.

According to an aspect, CCEs in one or more SSs are combined based on an AL. In one example, all CCEs in one USS having a same AL (e.g., SSK) may be combined to form one, larger AL. For illustrative purposes, all USS having an AL <NUM> may form one new AL. In another option of forming a union of CCEs based on existing ALs, all CCEs in the union of multiple (e.g., two or more) USSs define an AL (e.g., SSK ∪ SSK-<NUM>). Therefore the union of one USS having an AL k (SSK) and another USS having an AL k+<NUM> (SSK+<NUM>) may form a new AL. Advantageously, the union of CCEs from multiple USS will use the same scrambling ID for the PDCCH.

According to an aspect, the union of SSs that define the new AL may exclude CCEs included in the CSS. Because SSs are overlapping, the new AL may use only CCEs in the USSs and not in the CSS. In one example, the new AL includes the union of all CCEs in the USSs and excludes any of those CCEs which are part of the CSS. In another example, the new AL includes the union of CCEs having a same AL as defined by a standard and excludes any CCEs which may be part of the CSS.

Turning to UE processing capability, a UE may be limited with respect to how many CCEs the UE may process in a time slot. Currently, a network node configures the SS such that it does not exceed a UE's processing capability.

The new AL may include the union of CCEs the UE can process within one CORESET. In other words, the AL may include the union of CCEs that the UE is performing channel estimation for within one CORESET.

The gNB and the UE may agree on a rule to perform CCE pruning (dropping certain CCEs) in scenarios when the number of CCEs in the CORESET exceeds the UE processing capability. Accordingly, if a CORESET size is <NUM> and a UE has a processing capability to perform channel estimation on <NUM> CCEs, the rule may specify which <NUM> CCEs to use within the CORESET of <NUM> CCEs. The AL may include the union of CCEs the UE can process within on CORESET and may include only CCEs whose demodulation reference signal (DMRS) for the PDCCH are scrambled by a same ID.

According to aspects, the new ALs may be greater than <NUM> (the highest AL defined in NR Rel-<NUM>). According to aspects, the AL may be smaller than <NUM>, for example, when the gNB may not configure enough resources from the CORESET to form an AL greater than <NUM>. In some cases, the AL may not be a power of <NUM>. As an example, the AL may be <NUM>.

Given the new ALs, other considerations associated with DMRS, configuring a PDCCH candidate, DCI formats, and UE blind decodes may be necessary.

A DMRS may be used to estimate a channel for PDCCH and then for demodulation of the PDCCH. Each PDCCH is associated with its own UE-specific DMRS. gNBs have multiple antennas and may use beamforming to point reference signals to different UEs. A UE may not perform channel estimation on the DMRS that is aimed to other UEs, instead, the UE should perform channel estimation on the DMRS aimed for/directed to itself. However, because a UE may not know a priori which CCE will be used to convey its PDCCH, the UE performs blind detection. Because of the blind detection, there is a possibility that two consecutive CCEs may be used to transmit a PDCCH for two different UEs, and the UE may not perform channel estimation jointly on these two CCEs.

Because the UE may not perform channel estimation across CCEs (since different CCEs may contain RSs for different UEs having different beamforming directions/precoders), according to aspects, the UE may only perform channel estimation once for each CCE. The UE may not perform separate channel estimation for each AL or each blind decode. This may limit channel estimation performance as well as number of blind decodes that the UE may perform.

According to another aspect, a wideband RS may be used, where the DMRS for the PDCCH spans the entire CORESET bandwidth with the same precoder whenever there is PDCCH transmission. The gNB may not perform UE-specific beamforming for the DMRS that spans the entire bandwidth of the CORESET. Wideband DMRS may enhance the UE's channel estimation performance.

Currently, a gNB will configure a UE's CORESET and multiple SSs in the CORESET. Therefore, in accordance with aspects of the present disclosure, the UE is RRC configured with new ALs in addition to the regular (standards-defined) PDCCH candidates within each search space.

Currently, a search space is defined by the RRC-configured parameters: AL, number of candidates for this AL, and the PDCCH monitoring occasion. The new AL(s) may be configured by adding a new parameter (e.g., AL_max) to the existing RRC-configured parameters. According to aspects, a pre-agreed rule may exist between the UE and the gNB regarding which SSs to combine to determine a union of CCEs. By definition, only one decoding candidate for this AL exists. According to aspects, multiple new ALs may exist. Parameters e.g., AL_max1, AL_max2 may be used to configure the new ALs. Each of the new ALs may correspond to a pre-agreed rule to determine the union of CCEs as we discussed in this application.

The new AL may be used with a regular DCI format (e.g., DCI format agreed in NR Rel-<NUM>). DCI format is a predefined format in which the downlink control information is packed/formed and transmitted in PDCCH message. DCI is the information conveyed in the control channel before channel coding. NR supports several formats, called regular DCI formats. To further increase the reliability of PDCCH in NR, a new DCI format, that is much more compact (i.e., with a smaller payload size) than regular DCI, is introduced. The new ALs are compatible with both the NR Rel-<NUM> DCI formats and the compact DCI format.

A gNB needs to guarantee that the number of blind decodes performed by the UE does not exceed a pre-agreed value M. This value may be the same as in the case where the new AL is not introduced. The number of blind decodes may be restricted by using the new AL only for certain DCI format(s) (e.g., regular DCI formats agreed in NR Rel-<NUM>, or compact DCI). In an aspect, the number of blind decodes may be restricted by reducing the configured PDCCH candidates for each AL. In an example, if the UE is configured for <NUM> candidates for AL <NUM> for decoding the PDCCH, and a new AL is used, then the number of decoding candidates for the regular AL may be reduced from <NUM> to <NUM>. The number of blind decodes may be reduced by defining a rule, indicating to the UE, which blind decoding candidates to drop when the number of blind decodes exceeds a threshold value M. In an example, the new AL may be enabled only when decoding the new AL would not exceed the UE's blind decoding budget. Otherwise, the new AL may be dropped.

<FIG> illustrates example operations <NUM> for wireless communications, in accordance with aspects of the present disclosure. Operations <NUM> may be performed, for example, by a network node (e.g., a gNB), such as BS <NUM> shown in <FIG>.

Operations <NUM> begin, at <NUM>, where the network node generates a physical downlink control channel (PDCCH) message for transmission at an aggregation level (AL), wherein the AL comprises a union of control channel elements (CCEs) in one or more search spaces within a control resource set (CORESET). At <NUM>, the network node transmits the PDCCH message to a user equipment (UE) at the AL.

The UE performs complementary operations as the network node to decode the PDCCH transmitted in this manner.

For example, <FIG> illustrates example operations <NUM> a UE, such as UE <NUM> shown in <FIG>, may perform to decode a PDCCH transmitted according to operations <NUM> described above.

Operations <NUM> begin, at <NUM>, where the UE receives a physical downlink control channel (PDCCH) message at an aggregation level (AL), wherein the AL comprises a union of control channel elements (CCEs) in one or more search spaces within a control resource set (CORESET). At <NUM>, the UE decodes the PDCCH message at the AL.

As described above, in accordance with the present invention, search spaces in the UE's CORESET may be combined based on a scrambling ID used for the PDCCH. In one example, the union of CCEs includes the union of all CCEs in one or more SSs in the CORESET having a same PDCCH scrambling identification. The SSs includes USSs and a CSS. The network node may transmit the PDCCH scrambled using the scrambling ID at the new AL and the UE may decode the PDCCH at the new AL using the scrambling ID. In one example, the union may include the union of CCEs in one or more USSs and the CSS in the UE's CORESET that are associated with a same PDCCH scrambling ID.

As described above, in certain scenarios, the union of CCEs includes the union of all CCEs in all of the USSs in UE's CORESET. Further, due to potential differences in scrambling IDs, the union may exclude any CCEs included in the union of CCEs of the USS that are also part of the CSS. In this manner, the union excludes all CCEs in the CSS of the UE's CORESET.

In an example, the union of CCEs includes all CCEs in a CSS.

According to yet another example, the union of CCEs includes all CCEs in a first USS having a same AL. This union may further exclude any of the CCEs in the USS having a same AL that are also included in the CSS. The union may include a union of all CCEs in the first USS having a same AL and all CCEs in a second USS having a second AL (again, the union may exclude the CCEs in the first and second USS that overlap with the CSS. ) The union of these CCEs may form the new AL.

In another example, the union is based on the UE's processing capability. The union includes all CCEs within the CORESET on which the UE performs channel estimation. In an example, the union of CCEs comprises all CCEs within the UE's CORESET on which the UE performs channel estimation and all CCEs on which the DMRS for the PDCCH are scrambled by the same scrambling ID.

The new AL may be greater than a current maximum AL defined in a standard (e.g., <NUM>). However the new AL may be smaller than such a maximum AL if the network node does not (or may not be able to) configure enough CCEs in the CORESET for a higher AL.

According to aspects, a DMRS for the PDCCH may be transmitted using a same beamforming precoder, wherein the DMRS spans the entire bandwidth associated with the UE's CORESET.

In another example, the UE may be configured to refrain from decoding the PDCCH at the new AL when decoding the new AL would exceed the UE's decoding budget (e.g., max number of decodes M). The AL may be used based on the type or size of DCI. The type and/or size of DCI may be DCI as defined in NR Rel-<NUM>, or any other standard, or a compact DCI.

Thus, as described herein, ALs, in addition to the ALs defined in a standard, may be used in an effort to increase PDCCH reception reliability.

The methods described herein include one or more steps or actions for achieving the described method.

As used herein, including in the claims, the term "and/or," when used in a list of two or more items, means that any one of the listed items may be employed by itself, or any combination of two or more of the listed items may be employed. For example, if a composition is described as containing components A, B, and/or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. " For example, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from the context to be directed to a singular form. Unless specifically stated otherwise, the term "some" refers to one or more. " That is, unless specified otherwise, or clear from the context, the phrase, for example, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, for example the phrase "X employs A or B" is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B.

Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components. For example, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be configured to perform operations <NUM> of <FIG>, while processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> may be configured to perform operations <NUM> of <FIG>.

If implemented in hardware, an example hardware configuration may include a processing system in a wireless node.

Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, phase change memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof.

A software module may include a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may include a number of software modules.

Thus, in some aspects computer-readable media may include non-transitory computer-readable media (e.g., tangible media). In addition, for other aspects computer-readable media may include transitory computer-readable media (e.g., a signal).

Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in <FIG> and <FIG>.

Claim 1:
A method for wireless communications by a user equipment, UE, comprising:
receiving (<NUM>) a physical downlink control channel, PDCCH, message at an aggregation level, AL, wherein the AL comprises a union of control channel elements, CCEs, in a plurality of search spaces within a control resource set, CORESET;
receiving radio resource control, RRC, signaling of a parameter indicating a value of the AL;
determining, based on the indicated value of the AL and a predetermined rule, which of the plurality of search spaces within the CORESET to combine to determine the union of CCEs; and
decoding (<NUM>) the PDCCH message at the AL,
wherein:
the union of CCEs comprises a union of all CCEs in the plurality of search spaces having a same PDCCH scrambling identification, and
decoding the PDCCH at the AL comprises decoding using the scrambling identification,
wherein the plurality of search spaces comprise UE-specific search spaces, USSs, and a common search space, CSS.