Patent Description:
<CIT> relates to a user terminal that includes a receiving section that receives a downlink shared channel, and a control section that controls monitoring of the downlink shared channel in a time domain resource and a frequency domain resource of a cycle configured by higher layer signaling. <CIT> relates to wireless communication systems configured to provide piggyback downlink control information within the physical downlink shared channel (PDSCH). A first downlink control information portion may be transmitted within the physical downlink control channel (PDCCH) and may include information indicating a size of a second downlink control information portion transmitted within the PDSCH. <CIT> relates to methods and apparatus for downlink control information (DCI) communication and processing. One example method generally includes determining a limit, between a transmission time of a control channel carrying a DCI of a plurality of DCI and a time of an event enabled by the DCI, of a quantity of the plurality of DCI in a frame, generating a frame comprising the plurality of DCI in accordance with the determined limit, and transmitting the frame to a user-equipment (UE).

Methods, a base station apparatus, a User Equipmrnt, UE, apparatus and a computer program are provided as set out in the independent claims.

Aspects of the present disclosure provide apparatus, methods, and computer program for implementation of scheduling chains in accordance with certain limits to reduce error propagation.

The following description provides examples of scheduling chains in communication systems, and is not limiting of the scope, applicability, or examples set forth in the claims.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with <NUM>, <NUM>, and/or new radio (e.g., 5GNR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access 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 addition, these services may coexist in the same subframe. NR supports beamforming and beam direction may be dynamically configured.

As shown in <FIG>, the wireless communication network <NUM> may be in communication with a core network <NUM>. The core network <NUM> may in communication with one or more base station (BSs) <NUM> and/or user equipment (UE) <NUM> in the wireless communication network <NUM> via one or more interfaces.

As illustrated in <FIG>, the wireless communication network <NUM> may include a number of BSs 110a-z (each also individually referred to herein as BS <NUM> or collectively as BSs <NUM>) and other network entities. A network controller <NUM> may couple to a set of BSs <NUM> and provide coordination and control for these BSs <NUM> (e.g., via a backhaul).

The BSs <NUM> communicate with UEs 120a-y (each also individually referred to herein as UE <NUM> or collectively as UEs <NUM>) in the wireless communication network <NUM>. Wireless communication network <NUM> may also include relay stations (e.g., relay station <NUM>10r), also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS 110a or a UE 120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE <NUM> or a BS <NUM>), or that relays transmissions between UEs <NUM>, to facilitate communication between devices.

According to certain aspects, the BSs <NUM> and UEs <NUM> may be configured for configuration of scheduling chains. As shown in <FIG>, the BS 110a includes a scheduling manager <NUM>. The scheduling manager <NUM> may be configured to implement scheduling chains in accordance with various limits, in accordance with aspects of the present disclosure. As shown in <FIG>, the UE 120a includes a scheduling manager <NUM>. The scheduling manager <NUM> may be configured to implement scheduling chains in accordance with various limits, in accordance with aspects of the present disclosure.

At the BS 110a, 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. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

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 transmit processor <NUM> may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and channel state information reference signal (CSI-RS). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may 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) 232a-232t. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink <NUM>, and provide decoded control information to a controller/processor <NUM>.

On the uplink, at UE 120a, 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 modulators in transceivers 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas <NUM>, processed by the modulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE 120a.

Antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE 120a and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS 110a may be used to perform the various techniques and methods described herein. For example, as shown in <FIG>, the controller/processor <NUM> of the BS 110a has a scheduling manager <NUM>, according to aspects described herein. As shown in <FIG>, the controller/processor <NUM> of the UE 120a has a scheduling manager <NUM>, according to aspects described herein. Although shown at the controller/processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

Each subframe may include a variable number of slots (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., <NUM> or <NUM> symbols) depending on the SCS.

In certain implementations, downlink control information (DCI) may be communicated on a physical downlink shared channel (PDSCH) (also referred to as a data channel). Higher communication bands, such as a <NUM> band, may have shorter slot durations as compared to lower bands, such as frequency range (FR) <NUM> and FR2, due to the higher subcarrier spacing (SCS) (e.g., <NUM>, <NUM>, <NUM>) associated with the higher bands. Thus, the number of physical downlink control channel (PDCCH) monitoring occasions may increase, leading to high power consumption. Due to the short slot duration and narrow analog beamforming transmission on higher bands, the chance of sending multiple DCIs to different UEs is reduced as compared to FR1/FR2. Instead, it may be more likely for a BS (e.g., gNB) to send multiple DCIs to the same UE (e.g., in particular for bursty traffic). Thus, DCI may be transmitted on a data channel in order to reduce control channel monitoring density for a better micro sleep schedule at the UE, reducing power consumption. A DCI transmitted on a data channel (e.g., PDSCH) is generally referred to as a piggyback DCI (e.g., DCI piggybacked on PDSCH).

DCI piggybacking provides for a more efficient delivery of DCI, by sharing the PDSCH beam, precoding, and demodulation reference signal (DMRS). DCI piggybacking also provides for higher efficiency PDSCH transmission, with certain UEs only rate matching around the DCIs when receiving the PDSCH. In some cases, multiple piggyback DCIs may form a scheduling chain, with one piggyback DCI scheduling a data channel on which another piggyback DCI is transmitted, and so on. Certain aspects of the present disclosure are directed to techniques for providing limits scheduling chains implemented using DCI piggybacking.

<FIG> illustrates piggybacked DCIs forming a scheduling chain, in accordance with certain aspects of the present disclosure. As illustrated, a control resource set (CORESET) <NUM> may schedule resources for PDSCH <NUM>. The PDSCH <NUM> may include a DCI <NUM> (e.g., piggyback DCI) that schedules resources for PDSCH <NUM>. The PDSCH <NUM> may include a DCI <NUM> that schedules resources for PDSCH <NUM>. The PDSCH <NUM> includes DCI <NUM> which schedules resources for PDSCH <NUM>.

DCIs <NUM>, <NUM>, <NUM> are referred to as piggybacked DCIs because they are transmitted on PDSCH. DCIs <NUM>, <NUM>, <NUM> form a scheduling chain, as described herein. If a UE fails to successfully decode any DCI in the scheduling chain, the scheduling chain is broken and subsequent PDSCH transmissions and DCIs in the chain may not be received by the UE. For example, if the UE fails to decode DCI <NUM>, the UE may be unable to receive PDSCH <NUM>, <NUM>, and <NUM>. Thus, using piggyback DCIs to from a scheduling chain and schedule a large number of PDSCH transmissions sequentially may result in error propagation in case PDCCH decoding is unsuccessfully for one of the DCIs in the chain. This may especially be problematic given the bursty interference for millimeter wave (mmW) communications. Certain aspects of the present disclosure provide limits on the number of PDSCH that can be sequentially scheduled before the scheduling chain is ended, as described in more detail herein.

<FIG> is a flow diagram illustrating example operations <NUM> for wireless communication, in accordance with certain aspects of the present disclosure. The operations <NUM> may be performed, for example, by UE (e.g., such as a UE 120a in the wireless communication network <NUM>).

Operations <NUM> may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor <NUM> of <FIG>). Further, the transmission and reception of signals by the UE in operations <NUM> may be enabled, for example, by one or more antennas (e.g., antennas <NUM> of <FIG>). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor <NUM>) obtaining and/or outputting signals.

The operations <NUM> may begin, at block <NUM>, with the UE determining a limit associated with a quantity of a plurality of downlink control information (DCI) for each of at least one scheduling chain, each of at least one of the plurality of DCI to be transmitted on one of a plurality of data channels, and wherein each of the plurality of DCI in the scheduling chain schedules another one of the plurality of data channels. At block <NUM>, the UE may receive, from a base station, the plurality of DCI on the plurality of data channels in accordance with the determination.

<FIG> is a flow diagram illustrating example operations <NUM> for wireless communication, in accordance with certain aspects of the present disclosure. The operations <NUM> may be performed, for example, by a BS (e.g., such as the BS 110a in the wireless communication network <NUM>).

Operations <NUM> may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor <NUM> of <FIG>). Further, the transmission and reception of signals by the BS in operations <NUM> may be enabled, for example, by one or more antennas (e.g., antennas <NUM> of <FIG>). In certain aspects, the transmission and/or reception of signals by the BS may be implemented via a bus interface of one or more processors (e.g., controller/processor <NUM>) obtaining and/or outputting signals.

At block <NUM>, the BS may determine a limit associated with a quantity of a plurality of downlink control information (DCI) for each of at least one scheduling chain, each of at least one of the plurality of DCI to be transmitted on one of a plurality of data channels, and wherein each of the plurality of DCI in the scheduling chain schedules another one of the plurality of data channels. At block <NUM>, the BS may transmit the plurality of DCI on the plurality of data channels in accordance with the determination to a user-equipment (UE).

<FIG> illustrates a scheduling chain where a piggyback DCI may only schedule PDSCH that is transmitted before a subsequent CORESET occasion, in accordance with certain aspects of the present disclosure. In other words, the scheduling chain including piggybacked DCIs <NUM>, <NUM>, <NUM> begin with CORESET <NUM> that schedules the PDSCH <NUM> on which DCI <NUM> is transmitted. A subsequent CORESET <NUM> may begin another scheduling chain including DCIs <NUM>, <NUM>. As illustrated, DCI <NUM> is transmitted on PDSCH <NUM> and schedules PDSCH <NUM>, where DCI <NUM> is transmitted on PDSCH <NUM>.

In certain aspects, a DCI of a scheduling chain may be limited to only schedule a PDSCH that is prior to a subsequent CORESET (e.g., next CORESET instance). For example, DCIs <NUM>, <NUM>, <NUM> may be limited to only schedule a PDSCH that is prior to CORESET <NUM>. Thus, PDSCH <NUM> may not include a DCI because PDSCH <NUM> is the last PDSCH prior to CORESET <NUM>. Thus, the quantity of the DCIs in any particular chain may be limited by the quantity of PDSCH occasions between a CORESET instance (e.g., CORESET <NUM>) and the next CORESET instance (CORESET <NUM>). While <FIG> illustrates a DCI transmission chain being stopped at PDSCH <NUM> that is immediately before the next CORESET instance (e.g., CORESET <NUM>) to facilitate understanding, the DCI transmission chain may end on any PDSCH before the next CORESET instance.

<FIG> illustrates a scheduling chain where the last piggyback DCI in the chain is sent before the next CORESET instance, in accordance with certain aspects of the present disclosure. In this case, the PDSCH scheduled by a DCI of a chain may potentially be beyond the next CORESET instance (e.g., CORESET <NUM>). For example, DCI <NUM> may schedule resources for PDSCH <NUM>, and PDSCH <NUM> may include DCI <NUM>. DCI <NUM> may schedule a PDSCH that is after the next CORESET instances (e.g., CORESET <NUM>), such as the PDSCH <NUM>, as illustrated. However, in such a case, the PDSCH <NUM> may not continue the scheduling chain. In other words, the scheduling chain beginning with CORESET <NUM> ends with DCI <NUM> because DCI <NUM> schedules a PDSCH after the next CORESET instance.

While <FIG> illustrates PDSCH <NUM> immediately before the next CORESET instance (e.g., CORESET <NUM>) being the last PDSCH <NUM> of the scheduling chain that includes a DCI, effectively ending the scheduling chain, the last PDSCH that includes a piggyback DCI for the scheduling chain may be any PDSCH prior to the next CORESET instance. Moreover, the DCI <NUM> may schedule any PDSCH after the next CORESET instance or any subsequent CORESET instance (e.g., any upcoming Nth CORESET instance, N being greater than <NUM>). For unlicensed bands, the final DCI in the chain may schedule any PDSCH prior to an end of a corresponding transmission opportunity (TxOP).

<FIG> illustrates a scheduling chain implemented in accordance with a configured maximum quantity of piggyback DCIs, in accordance with certain aspects of the present disclosure. For example, the BS may configure or a specification may specify the maximum number of chain DCIs. Once the limit is crossed, the UE may wait for the next CORESET instance to receive a grant. For example, as illustrated, a limit of three chain DCIs may be implemented. In other words, DCI <NUM> may schedule PDSCH <NUM>, DCI <NUM> may schedule PDSCH <NUM>, and DCI <NUM> may schedule PDSCH <NUM>. While DCI <NUM> may schedule PDSCH <NUM>, PDSCH <NUM> may not include another piggyback DCI because the limit for the quantity of DCIs in the chain has been reached.

<FIG> illustrates multiple parallel scheduling chains, in accordance with certain aspects of the present disclosure. Multiple parallel scheduling chains may be used to reduce (e.g., limit) the impact of error propagation. For example, three parallel scheduling chains may begin with respective CORESETs <NUM>, <NUM>, <NUM>.

As illustrated, CORESET <NUM> may schedule PDSCH <NUM>. As illustrated, hybrid automatic request (HARQ)-acknowledgement (ACK) resource <NUM> may be scheduled for transmission of either an ACK or negative ACK (NACK) for PDSCH <NUM> (e.g., for slot <NUM>). If the BS receives a NACK for Slot <NUM> in the HARQ-ACK resource <NUM> at the end of Slot <NUM>, then the BS may estimate (e.g., assume) that the piggyback DCI <NUM> (e.g., PDCCH) in slot <NUM> will not be decoded. The piggyback DCI <NUM> may schedule resources for Slot <NUM>. Thus, because the BS assumes that the piggyback DCI <NUM> is not decoded, the BS may also assume that PDSCH and piggyback DCI (e.g., PDCCH) that would be present in Slot <NUM> will also not be decoded. Therefore, the BS may determine to end the scheduling chain by forgoing inclusion of a DCI in slot <NUM> that continues the chain.

To facilitate such decision making by the BS, the next PDSCH in a scheduling may be scheduled after K0 + K1 + K3 slots, K0 indicating the number of slots from PDCCH (e.g. CORESET <NUM>) to PDSCH (e.g., PDSCH <NUM>), K1 indicating the number of slots from PDSCH (e.g., PDSCH <NUM>) to ACK (e.g., HARQ-ACK resource <NUM>), and K3 indicating the number of slots from ACK (e.g., HARQ-ACK resource <NUM>) to the next PDCCH (e.g., in slot <NUM>). In the example given with respect to <FIG>, K1, K2, and K3 are each equal to <NUM> as there is one slot between CORESET <NUM> and slot <NUM> (e.g., the scheduled PDSCH <NUM>), one slot between slot <NUM> and HARQ-ACK resource <NUM>, and one slot between HARQ-ACK resource <NUM> and slot <NUM>. In this manner, the error propagation for each chain may be limited to a single slot.

In some cases, the UE may fail PDSCH decoding in Slot <NUM> but decode the DCI <NUM> that schedules a PDSCH in slot <NUM>. Thus, the UE may be expecting a PDSCH and potentially a piggyback PDCCH in slot <NUM>. In certain aspects of the present disclosure, the BS may transmit the PDSCH <NUM> in slot <NUM> and send a null piggyback PDCCH <NUM> (e.g., a null DCI) in slot <NUM>, but terminate the chain. In other words, the null PDCCH may be a PDCCH that does not schedule any other transmissions.

In some cases, the UE may fail PDSCH decoding for slot <NUM> and also fail piggyback DCI decoding in slot <NUM>. Thus, the UE may not expect a PDSCH in slot <NUM>. Thus, in certain aspects of the present disclosure, the BS may skip the full transmission in slot <NUM> as the BS assumes that the UE will not decode PDSCH and PDCCH that would otherwise be included in slot <NUM>.

In certain aspects, the HARQ-ACK resource <NUM> may indicate an ACK or NACK for PDSCH in slot <NUM>, and indicate an ACK or NACK for PDCCH in slot <NUM>. Thus, the BS may determine whether the UE has failed to decode the PDSCH and PDCCH in slot <NUM>, or only fails to decode the PDSCH in slot <NUM> and has successfully decoded the PDCCH in slot <NUM>. Accordingly, the BS may determine whether to transmit a null piggyback PDCCH in slot <NUM>, or fully forgo the transmission in slot <NUM> to the UE.

Certain aspects of the present disclosure are directed to techniques starting a scheduling chain when another chain is terminated. For example, in certain aspects, a scheduling chain may be started by scheduling a piggyback PDCCH from other ongoing chains (e.g., chains starting with CORESETs <NUM>, <NUM>). In certain aspects, a piggyback PDCCH may be used to dynamically trigger the UE to monitor a new search space location. For example, a new CORESET search space may be configured in response to a scheduling chain being terminated. That is, if a NACK is received in the HARQ-ACK resource <NUM>, the scheduling chain starting with CORESET <NUM> may be terminated. In this case, a new CORESET may be scheduled that begins a new scheduling chain. For example, the new CORESET in a slot may be indicated in a DCI in slot <NUM>.

In certain aspects, a configuration for a new scheduling chain may be preconfigured at the UE. The location of the configured schedule chain may be specified in a triggering piggyback DCI. In some cases, a search space may already be scheduled for the UE to start a new scheduling chain. Generally, it is preferable to use piggybacked grants for long durations. A PDCCH search space (e.g., CORESET) may be used to start a new scheduling chain if necessary.

The communications device <NUM> includes a processing system <NUM> coupled to a transceiver <NUM> (e.g., a transmitter and/or a receiver).

The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium/memory <NUM> via a bus <NUM>. In certain aspects, the computer-readable medium/memory <NUM> is configured to store instructions (e.g., computer-executable code) that when executed by the processor <NUM>, cause the processor <NUM> to perform the operations illustrated in <FIG>, or other operations for performing the various techniques discussed herein for implementation of scheduling chains. In certain aspects, computer-readable medium/memory <NUM> stores code <NUM> for determining; and code <NUM> for outputting for transmission or obtaining. In certain aspects, the processor <NUM> has circuitry configured to implement the code stored in the computer-readable medium/memory <NUM>. The processor <NUM> includes circuitry <NUM> for determining; and circuitry <NUM> for outputting for transmission or obtaining.

Claim 1:
A method (600A) for wireless communications, comprising:
determining (605A) a limit associated with a quantity of a plurality of downlink control information, DCI, for each of at least one scheduling chain, each of at least one of the plurality of DCI to be transmitted on one of a plurality of data channels, and wherein each of the plurality of DCI in the scheduling chain schedules another one of the plurality of data channels; and
transmitting (610A) the plurality of DCI on the plurality of data channels in accordance with the determination to a user-equipment, UE,
further comprising receiving a hybrid automatic repeat request, HARQ, indication associated with one of the data channels having a DCI of the plurality of DCI, wherein the determining of the limit is based on the HARQ indication.