Patent Description:
Aspects of the present disclosure relate generally to wireless communications systems, and more particularly, to a slot format indicator (SFI) and slot aggregation level indication in a group common physical downlink control channel (GC PDCCH) and conflict handling for the SFI in certain systems, such as new radio (NR) systems.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

In some examples, a wireless multiple-access communication system may include a number of base stations (BSs) that each can simultaneously support communication for multiple communication devices, otherwise known as user equipment (UEs). In an LTE or LTE-A network, a set of one or more BSs may define an e NodeB (eNB). In other examples (e.g., in a next generation, new radio (NR), 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 DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, next generation NB (gNB), TRP, etc.). A BS or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a BS or to a UE) and uplink channels (e.g., for transmissions from a UE to a BS or DU).

NR is an example of an emerging telecommunication standard.

3GPP document R1-<NUM> describes aspects of group common PDCCH. 3GPP draft R1-<NUM> describes aspects of PCFICH channels. 3GPP document R1-<NUM> describes aspects of group common PDCCH. 3GPP draft R1-<NUM> describes aspects of slot aggregation.

A method for wireless communications by a user equipment, UE, is provided comprising: receiving (<NUM>) a downlink control channel including a slot format indicator, SFI and an uplink or downlink grant for transmission; and determining (<NUM>) a format of a current slot based on the SFI and the uplink or downlink grant, wherein the format of the current slot is determined based at least in part on prioritizing the uplink or downlink grant given the SFI.

A method for wireless communications, is also provided comprising: determining (<NUM>) at a base station, BS, a format of one or more slots; and sending (<NUM>) a downlink control channel to a UE, including a slot format indicator, SFI, indicating the format of the one or more slots and an uplink or downlink grant for a transmission, wherein the format of the one or more slots is determined at the UE based at least in part on prioritizing the uplink or downlink grant given the SFI.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for NR (new radio access or <NUM> technology). NR may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., <NUM> or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., <NUM> or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC).

In NR, slots, and symbols within slots, may take various configurations, such as downlink, uplink, empty, reserved (e.g., for data only or control only), etc. A slot format indicator (SFI) may carry information that indicates the format of a current slot (and/or a future slot). The SFI may be carried in a downlink region of a slot, for example in a downlink control channel such as the group common physical downlink control channel (GC PDCCH). In NR, slots can be aggregated (referred to as an aggregated slot). In some examples, an aggregated slot has control regions (uplink and/or downlink) in the middle. In this case, the SFI can be sent for each slot. However, in some cases, there is only a downlink control region at the beginning of the aggregated slot. In this case, it is desirable for the user equipment (UE) to have some information about the aggregation level.

In addition, in some cases the SFI may conflict with other scheduled transmissions, such as grants or ACK/NACK (acknowledgement/negative acknowledgement) timing in downlink control information (DCI) or periodic signaling. Thus, techniques for conflict handling/resolution for SFI and other transmissions are desirable.

Aspects of the present disclosure provide techniques and apparatus for SFI and aggregation level indication in the downlink control channel and for SFI conflict handling.

For example, the wireless communication network <NUM> may be a new radio (NR) or <NUM> network. As illustrated in <FIG>, the wireless network <NUM> may include a number of base stations (BSs) <NUM> and user equipment (UE) <NUM>. A BS <NUM> in wireless communication network <NUM> can determine a slot aggregation level and a format of the aggregated slots and send the UE <NUM> a slot format indicator (SFI) indicating the format of the aggregated slot in the downlink control channel (e.g., in a group common physical downlink control channel (GC PDCCH)). In addition, the BS can send the UE <NUM> an indication of the slot aggregation level in the downlink control channel. The UE <NUM> can receive the downlink control channel including the SFI and the indication of a slot aggregation level and determine a format of a current slot based on the received SFI and slot aggregation level. The BS <NUM> may send downlink control information (DCI) including an uplink or downlink grant or ACK/NACK timing information that conflicts with the SFI. Also, the BS <NUM> and/or the UE <NUM> may be configured with uplink or downlink periodic signaling that may conflict the SFI. The UE <NUM> may determine whether to follow the SFI, DCI, or periodic signaling for the symbols in the slots.

A BS may be a station that communicates with UEs. Each BS <NUM> may provide communication coverage for a particular geographic area. In NR systems, the term "cell" and next generation NB (gNB), BS, NR BS, BS, transmission reception point (TRP), etc., may be interchangeable. In some examples, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in wireless communication 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 RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a frequency channel, a tone, a subband, a subcarrier, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

Wireless communication network <NUM> may be a heterogeneous network that includes BSs of different types (e.g., macro BS, pico BS, femto BS, relays, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless communication network <NUM>. For example, a macro BS may have a high transmit power level (e.g., <NUM> Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., <NUM> Watt).

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 biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, 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, industrial manufacturing equipment, a global positioning system device, 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.

For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a resource block (RB)) 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> (i.e., <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.

BSs are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs utilize resources scheduled by the UE for wireless communication. In a mesh network example, UEs may communicate directly with one another in addition to communicating with the scheduling entity.

<FIG> illustrates an example logical architecture of a distributed RAN <NUM>, which may be implemented in the wireless communication network <NUM> illustrated in <FIG>. ANC <NUM> may be a CU of the distributed RAN <NUM>. The backhaul interface to the next generation core network (NG-CN) <NUM> may terminate at ANC <NUM>. The backhaul interface to neighboring next generation access nodes (NG-ANs) <NUM> may terminate at ANC <NUM>. ANC <NUM> may include one or more TRPs <NUM> (e.g., cells, BSs, gNBs, etc.). The TRPs <NUM> may be connected to a single ANC (e.g., ANC <NUM>) or more than one ANC (not illustrated). For example, for RAN sharing, radio as a service (RaaS), and service specific AND deployments, the TRPs <NUM> may be connected to more than one ANC. A TRPs <NUM> may include one or more antenna ports. The TRPs <NUM> may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE.

The logical architecture of the distributed RAN <NUM> may support fronthauling solutions across different deployment types. The local architecture of the distributed RAN <NUM> may share features and/or components with LTE. NG-AN <NUM> may support dual connectivity with NR and may share a common fronthaul for LTE and NR. The logical architecture of the distributed RAN <NUM> may enable cooperation between and among TRPs <NUM>, for example, within a TRP and/or across TRPs via the ANC <NUM>.

Logical functions may be dynamically distributed in the logical architecture of the distributed RAN <NUM>. As will be described in more detail with reference to <FIG>, the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and a Physical (PHY) layers may be adaptably placed at the DU (e.g., the TRP <NUM>) or CU (e.g., the ANC <NUM>).

C-RU <NUM> may host core network functions locally. C-RU <NUM> may have distributed deployment. C-RU <NUM> may be located near the network edge.

The DU <NUM> may be located at edges of the network with radio frequency (RF) functionality.

<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. 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 BS <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), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared Channel (PDSCH), etc. For example, according to certain aspects of the present disclosure the BS <NUM> can send a slot format indicator (SFI), slot aggregation level information, and/or downlink control information (DCI) in a downlink control region. 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, such as primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS).

At UE <NUM>, the antennas 452a through 452r may receive the downlink signals from BS <NUM> and may provide received signals to the demodulators (DEMODs) 454a through 454r, respectively. For example, according to certain aspects of the present disclosure the UE <NUM> can receive a slot format indicator (SFI), slot aggregation level information, and/or downlink control information (DCI) from the BS <NUM> in a downlink control region.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source <NUM> and control information (e.g., for the physical uplink control channel (PUCCH)) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the demodulators 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to BS <NUM>.

The controllers/processors <NUM> and <NUM> may direct the operation at BS <NUM> and UE <NUM>, respectively. The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of various processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct, such as the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. For example, according to certain aspects of the present disclosure, processors of the UE <NUM> can determine a direction for one or more symbols in at least a current slot based on the SFI, DCI, and/or slot aggregation information received from the BS <NUM> and/or based on periodic signaling. The processor <NUM> and/or other processors and modules at the BS <NUM> may also perform or direct, such as the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein.

Diagram <NUM> illustrates a communications protocol stack including a RRC layer <NUM>, a PDCP layer <NUM>, a RLC layer <NUM>, a MAC layer <NUM>, and a PHY layer <NUM>. Layers of the protocol stack may be implemented as separate modules of software, portions of a processor or ASIC, portions of non-collocated devices connected by a communications link, or various combinations thereof.

A mini-slot is a subslot structure (e.g., <NUM>, <NUM>, or <NUM> symbols).

Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V) communications, Internet-of-Everything (IoE) communications, IoT communications, mission-critical mesh, and/or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., a UE) to another subordinate entity (e.g., another UE) without relaying that communication through the scheduling entity (e.g., UE or BS), even though the scheduling entity may be utilized for scheduling and/or control purposes.

In NR, slots may take various configurations. For example, based on the slot format, the symbols in the slot may have different configurations, such as downlink, uplink, empty (e.g., empty data region), reserved (e.g., forced discontinuous transmission (DTX) or discontinuous reception (DRX) in data region only, control only, or data and control, etc.), etc..

The base station (BS), such as a BS <NUM> in the wireless communication network <NUM> illustrated in <FIG>, can send information to a user equipment (UE) (e.g., a UE <NUM>) regarding the slot format in a downlink control region. For example, the BS can send the information to the UE in a downlink control channel, such as the group common (GC) physical downlink control channel (PDCCH). The GC PDCCH refers to a channel, for example a PDCCH, that carries information, such as a slot format indicator (SFI) via common downlink control information (DCI), intended for a group of UEs. The UEs may be radio resource control (RRC) configured to decode the GC PDCCH. A SFI indicates the format of a current slot and/or future slot(s). The UE can use the information in the SFI to determine (identify, derive, etc.) which symbols in a slot are for uplink or downlink, or other purposes (e.g., such as sidelink, blank, or reserved).

In NR, slots may be aggregated. The number of aggregated slots is based on the slot aggregation level. For slot aggregation, it may be desirable to include additional information, such as format information for multiple slots (current and future slots). <FIG> illustrated an aggregated slot <NUM> that has control regions (uplink and/or downlink) in the middle. In the aggregated slot <NUM> shown in <FIG>, the slots <NUM>, <NUM>, and <NUM> each have a downlink control region at the beginning and an uplink control region at the end. Thus, the SFI <NUM>, <NUM>, <NUM> can be sent in the downlink control region of each slot <NUM>, <NUM>, <NUM>, respectively. However, in some cases with slot aggregation, there is only a downlink control region at the beginning of the aggregated slot. As shown in <FIG>, the aggregated slot <NUM> has a downlink control region in the first slot <NUM>, in which SFI <NUM> can be sent, and an uplink control region at the end of slot <NUM> and no control regions in the middle slot <NUM>. Thus, special handling may be desirable to indicate the format for the aggregated slots.

In addition, as will described in more detail below, SFI may conflict with other scheduled transmissions, such as those scheduled by a grant (uplink and/or downlink) in downlink control information (DCI), ACK/NACK timing (e.g., timing for providing ACK/NACK feedback or a retransmission for HARQ), and/or periodic signaling (uplink or downlink). For example, the SFI may indicate certain symbols as for uplink, downlink, empty, or reserved, while a scheduled transmission for that symbol may be in the other direction. Accordingly, techniques SFI conflict handling/resolution are also desirable.

Aspects of the present disclosure provide techniques and apparatus for SFI and aggregation level indication in the downlink control channel, as well as techniques (e.g., rules) for handling conflict between SFI and other signaling.

<FIG> is a flow diagram illustrating example operations <NUM> for SFI and slot aggregation indication, in accordance with certain aspects of the present disclosure. Operations <NUM> may be performed, for example, by a BS (e.g., such as a BS <NUM>). Operations <NUM> may begin, at <NUM>, by determining a slot aggregation level and a format of the aggregated slots. At <NUM>, the BS sends a downlink control channel (e.g., GC PDCCH) including a SFI indicating the format of the aggregated slot and an indication of the slot aggregation level.

<FIG> is a flow diagram illustrating example operations <NUM> for determining a format of aggregated slots, in accordance with certain aspects of the present disclosure. Operations <NUM> may be performed, for example, by a UE (e.g., such as a UE <NUM>). Operations <NUM> may be complementary operations by the UE to the operations <NUM> performed by the BS. Operations <NUM> may begin, at <NUM>, by receiving the downlink control channel including the SFI and the indication of the slot aggregation level. At <NUM>, the UE determines a format of a current slot (e.g., determine a direction to apply for the symbols in the slot) based on the received SFI and the slot aggregation level. In aspects, the UE can determine the format of one or more future slots as well based on the received SFI and the slot aggregation level. For example, the UE can determine the format of each of the aggregated slots.

According to certain aspects, in the case that aggregated slot does not have control regions in the middle, for example, as shown in <FIG>, then it may be desirable to include additional information in the downlink control channel (e.g., in the GC PDCCH) in addition to the information in the SFI. For example, the aggregation level of the slot (e.g., which indicates the number of aggregated slots) may be indicated in the downlink control channel (e.g., in separate fields) at the beginning of the aggregated slot.

The UE receiving the downlink control channel may be able to use the information, including the SFI and the aggregation level, to determine (derive, identify, etc.) the format of a current slot and/or future slots, such as which symbols in the slot are for uplink and which symbols are for downlink. In aspects, the UE can skip PDCCH decoding during aggregated slots.

It may be desirable that information in the SFI does not conflict with other signaling, such as downlink control information (DCI) (e.g., uplink grants, downlink grants, and/or ACK/NACK timing) and pre-configured periodic uplink or downlink transmissions. There can be false detection with GC PDCCH. For example, the DCI can schedule an uplink or downlink transmission (or there can be a periodic uplink or downlink transmission) in a symbol, while the SFI may indicate that symbol as non-uplink (e.g., downlink, reserved, empty, etc.) or non-downlink (e.g., uplink, reserved, empty, etc.).

In an example scenario, information in the SFI may indicate that one or more symbols are for either uplink or downlink (or reserved, empty, etc.); however, a grant in the DCI and/or ACK/NACK timing information in the DCI may schedule a UE for transmitting or receiving a transmission in the other direction in one of those symbols. There also can be detection error either in DCI or SFI. Thus, the SFI and DCI can conflict. If the UE determines that there is a conflict, the UE may give priority to either the information in the SFI or the information in the DCI. In one example, the UE always gives priority to the information in the DCI. Alternatively, the UE may only give priority to a DCI received in the current slot, but if the DCI was received in a previous slot, then the UE may give priority to the information in the SFI.

In another example scenario, information in the SFI may conflict with periodic signaling. On downlink, periodic signaling may include such signaling as channel state information reference signals (CSI-RS), synchronization signals (primary synchronization signal (PSS), secondary synchronization signal (SSS), and/or physical broadcast channel (PBCH)), and/or semi-persistent scheduling (SPS). On the uplink, periodic signaling may include sounding reference signal (SRS), physical uplink control channel (PUCCH) with channel state information (CSI), and/or SPS. Information in the SFI may indicate that one or more symbols are for either uplink or downlink (or reserved, empty, etc.); while some periodic signal may occur in the other directions in those symbols. Thus, the SFI and periodic signaling conflict. If the UE determines that there is a conflict, the UE may give priority to either the information in the SFI or the periodic signaling.

In one example, if there is DCI information for the symbol, the UE always gives priority to the information in the DCI. Alternatively, if there is DCI information for the symbol, the UE may only give priority to the information in the DCI if the DCI is received in the current slot-not to DCI received in a previous slot. If DCI is not present (or does not include a grant for that symbol), and if the SFI indicates a direction, the UE gives priority to the information in the SFI. If DCI is not present and the SFI indicates empty, the UE gives priority to the periodic signaling. And if DCI is not present and the SFI indicates reserved, the UE gives priority to the SFI.

Giving priority to the information in the DCI may include transmitting or monitoring for a transmission based on an uplink or downlink grant in the DCI (e.g., ignoring the link direction indicated by the SFI) or based on the ACK/NACK timing in the DCI. Giving priority to the SFI may include ignoring the uplink or downlink grant or ACK/NACK timing in the DCI if it conflicts with the information in the SFI. Giving priority to the periodic signaling may include transmitting or monitoring for the periodic signaling regardless of the information in the SFI or DCI.

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. §<NUM>, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for.

Claim 1:
A method for wireless communications by a user equipment, UE, comprising:
receiving (<NUM>) a downlink control channel including a slot format indicator, SFI and an uplink or downlink grant for transmission; and
determining (<NUM>) a format of a current slot based on the SFI and the uplink or downlink grant, wherein the format of the current slot is determined based at least in part on prioritizing the uplink or downlink grant given the SFI.