Patent Description:
<CIT> relates to techniques for pre-allocating virtual resource to user terminals, and activating the virtual resource in case of need, so user terminals can use the pre-allocated resource to exchange data with network side. When inactive, the virtual resource can be allocated to other users. <CIT> relates to configures at a base station at least two user equipments into a UE group for aggregate transmission by sending a control message from the base station to the at least two user equipments.

Additionally, wireless communication systems in factory automation have stringent reliability and latency requirements. Sensor, actuators, control commands and related signals typically need to communicate and work in coordinated fashion where delay or loss of signal could result in a catastrophic system failure. Accordingly, factory automation has additional implementation challenges when designing wireless communication systems.

Such improvements are facilitated by the invention recited in the independent claims. Advantageous embodiments are subject to the dependent claims. An embodiment is directed to a method of operating a base station of a communications network, comprising transmitting, on a set of resources, a first communication to each of a plurality of user equipments (UEs), receiving acknowledgments (ACKs) to the transmitted first communications from a first subset of the plurality of UEs, determining that a second subset of the plurality of UEs has failed to acknowledge the transmitted first communications, configuring a group scheduling message that indicates an allocation of the set of resources to the second subset of UEs based on a predetermined resource reallocation scheme, transmitting the group scheduling message to the second subset of UEs, and transmitting, on the set of resources, a second communication to each UE in the second subset of UEs in accordance with the indicated allocation from the group scheduling message.

Another embodiment is directed to a method of operating a user equipment (UE) of a communications network, comprising receiving, from a base station, a group scheduling message that indicates an allocation of a set of resources to a subset of a plurality of UEs that each failed to acknowledge a respective first communication among a plurality of first communication transmissions from the base station, the indicated allocation of the set of resources being based on a predetermined resource reallocation scheme, determining, from the indicated allocation of the set of resources in the group scheduling message, a subset of the set of resources allocated to the UE, and receiving, from the base station, a second communication on the subset of resources allocated to the UE.

Another embodiment is directed to a base station of a communications network, comprising means for transmitting, on a set of resources, a first communication to each of a plurality of user equipments (UEs), means for receiving acknowledgments (ACKs) to the transmitted first communications from a first subset of the plurality of UEs, means for determining that a second subset of the plurality of UEs has failed to acknowledge the transmitted first communications, means for configuring a group scheduling message that indicates an allocation of the set of resources to the second subset of UEs based on a predetermined resource reallocation scheme, means for transmitting the group scheduling message to the second subset of UEs, and means for transmitting, on the set of resources, a second communication to each UE in the second subset of UEs in accordance with the indicated allocation from the group scheduling message.

Techniques for opportunistic retransmission based on a dynamic reassignment of downlink resources are disclosed. More specific aspects of the disclosure are provided in the following description and related drawings directed to various examples provided for illustration purposes. Additionally, well-known aspects of the disclosure may not be described in detail or may be omitted so as not to obscure more relevant details.

In some aspects, the BSs <NUM>10a-d may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the access network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

In the example shown in <FIG>, a relay base station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between macro BS 110a and UE 120d.

In some aspects, two or more UEs <NUM> (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a BS <NUM> as an intermediary to communicate with one another). In this case, the UE <NUM> may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the BS <NUM>.

<FIG> shows a block diagram of a system <NUM> including BS <NUM> and UE <NUM>, which may be one of the base stations and one of the UEs in <FIG>. BS <NUM> may be equipped with T antennas 234a through 234t, and UE <NUM> may be equipped with R antennas 252a through 252r, where in general T ≥ <NUM> and R ≥ <NUM>.

At BS <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. According to certain aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE <NUM>, antennas 252a through 252r may receive the downlink signals from BS <NUM> and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. A channel processor (e.g., receive processor <NUM> and/or controller/processor <NUM>) may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), and/or the like.

The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to BS <NUM>. At BS <NUM>, the uplink signals from UE <NUM> and other UEs may be received by antennas <NUM>, processed by demodulators <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 UE <NUM>. BS <NUM> may include communication unit <NUM> and communicate to network controller <NUM> via communication unit <NUM>.

Controller/processor <NUM> of BS <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with opportunistic retransmission of communications, such as mission-critical communications, as described in more detail elsewhere herein. For example, controller/processor <NUM> of BS <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, processes <NUM>-<NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for BS <NUM> and UE <NUM>, respectively.

In some aspects, a scheduling entity (e.g., UE <NUM> and/or BS <NUM>) may include means for performing various actions, in particular, the actions described below with respect to the processes <NUM>-<NUM> of <FIG>. In some aspects, such means may include one or more components of UE <NUM> and/or one or more components of BS <NUM> described in connection with <FIG>.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communication systems, such as NR or <NUM> technologies.

In aspects, NR may utilize OFDM with a CP (herein referred to as cyclic prefix OFDM or CP-OFDM) and/or SC-FDM on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using time division duplexing (TDD). NR may include Enhanced Mobile Broadband (eMBB) service targeting wide bandwidth (e.g., <NUM> megahertz (MHz) and beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., <NUM> gigahertz (GHz)), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission-critical targeting ultra reliable low latency communications (URLLC) service.

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> kilohertz (kHz) over a <NUM> duration. Each radio frame may include <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 downlink/uplink (DL/UL) data as well as DL/UL control data.

The RAN may include a central unit (CU) and distributed units (DUs). A NR BS (e.g., gNB, <NUM> Node B, Node B, transmit receive point (TRP), access point (AP)) may correspond to one or multiple BSs. NR cells can be configured as access cells (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) can 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 cases, DCells may transmit synchronization signals. NR BSs may transmit downlink signals to UEs indicating the cell type. Based at least in part 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 at least in part on the indicated cell type.

The local architecture of the distributed RAN <NUM> may be used to illustrate fronthaul definition.

According to aspects, a dynamic configuration of split logical functions may be present within the architecture of the distributed RAN <NUM>.

<FIG> is a diagram <NUM> showing an example of a DL-centric subframe or wireless communication structure. In some aspects, the control portion <NUM> may include legacy PDCCH information, shortened PDCCH (sPDCCH) information), a control format indicator (CFI) value (e.g., carried on a physical control format indicator channel (PCFICH)), one or more grants (e.g., downlink grants, uplink grants, and/or the like), and/or the like.

The DL-centric subframe may also include an UL short burst portion <NUM>. The UL short burst portion <NUM> may sometimes be referred to as an UL burst, an UL burst portion, a common UL burst, a short burst, an UL short burst, a common UL short burst, a common UL short burst portion, and/or various other suitable terms. In some aspects, the UL short burst portion <NUM> may include one or more reference signals. Additionally, or alternatively, the UL short burst portion <NUM> may include feedback information corresponding to various other portions of the DL-centric subframe. For example, the UL short burst portion <NUM> may include feedback information corresponding to the control portion <NUM> and/or the data portion <NUM>. Non-limiting examples of information that may be included in the UL short burst portion <NUM> include an acknowledgment (ACK) signal (e.g., a physical uplink control channel (PUCCH) ACK, a physical uplink shared channel (PUSCH) ACK, an immediate ACK), a negative acknowledgment (NACK) signal (e.g., a PUCCH NACK, a PUSCH NACK, an immediate NACK), a scheduling request (SR), a buffer status report (BSR), a hybrid automatic repeat request (HARQ) indicator, a channel state indication (CSI), a channel quality indicator (CQI), a sounding reference signal (SRS), a demodulation reference signal (DMRS), PUSCH data, and/or various other suitable types of information. The UL short burst portion <NUM> may include additional or alternative information, such as information pertaining to random access channel (RACH) procedures, scheduling requests, and various other suitable types of information.

<FIG> is a diagram <NUM> showing an example of an UL-centric subframe or wireless communication structure. 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 long burst portion <NUM>. The UL long burst 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).

The UL-centric subframe may also include an UL short burst portion <NUM>. The UL short burst portion <NUM> in <FIG> may be similar to the UL short burst portion <NUM> described above with reference to <FIG>, and may include any of the information described above in connection with <FIG>. The foregoing is merely one example of an UL-centric wireless communication structure, and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

In some aspects, the sidelink signals may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum).

Some wireless communications may be associated with stringent latency and/or reliability requirements. As one example, factory automation services may use wireless communications, and, in some aspects, may have latency requirements in the range of <NUM> to <NUM> and reliability requirements in the range of 10e-<NUM> to 10e-<NUM>. Mission-critical traffic for factory automation may tend to be periodic, and may include cyclic exchanges among programmable logic controllers (PLCs) and sensors and/or actuators (S/A). In some aspects, the PLC (or a base station or UE associated with the PLC) may act as a scheduling entity for the S/As. In such a case, the PLC may function as a master and the S/As may function as slaves.

<FIG> illustrates a Coordinated Multipoint (CoMP) network <NUM> in accordance with an embodiment of the disclosure. In particular, the CoMP network <NUM> of <FIG> represents an example of an industrial IoT network (e.g., for monitoring and/or controlling various devices or sensors deployed in a factory setting). In an example, wireless communication may be implemented in the CoMP network <NUM> may be implemented in accordance with a wireless communications protocol, including but not limited to Wireless Speaker & Audio Association (WISA) based on an IEEE <NUM>. <NUM> (Bluetooth) PHY with a modified MAC layer (e.g., up to <NUM> latency with 10e-<NUM> reliability), Wireless Highway Addressable Remote Transducer Protocol (WirelessHART) based on IEEE <NUM>. <NUM> (ZigBee) PHY/MAC (e.g., for factory automation with low-power sensors), or <NUM> URLLC Rel. <NUM> based on a mini-slot structure with URLLC-specific signaling (e.g., sPDCCH, SR, Indicator, etc.).

Referring to <FIG>, the CoMP network <NUM> includes a management system <NUM>, human machine interfaces (HMIs) <NUM>-<NUM>, programmable logic controllers (PLCs) <NUM>-<NUM> and sensor/actuators (S/As) <NUM>-<NUM>. In <FIG>, the various interconnections (or arrows) between the various CoMP network components may correspond to wired or wireless communications interfaces.

Referring to <FIG>, the management system <NUM> includes controller programming, manages software and security for the CoMP network <NUM>, and performs long-term key performance indicator (KPI) monitoring. The HMIs <NUM>-<NUM> include user devices (e.g., tablet computers, panels, wearable computers, etc.). For example, the HMIs <NUM>-<NUM> may permit machine control by authorized personnel at the factory floor (e.g., Start/Stop certain machinery, change a mode of a particular machine from `widget <NUM>' to `widget <NUM>', etc.). The HMIs <NUM>-<NUM> may optionally provide an augmented reality (AR) user interface or a virtual reality (VR) user interface.

Referring to <FIG>, the PLCs <NUM>-<NUM> may communicate with the S/As <NUM>-<NUM>. For example, the PLCs <NUM>-<NUM> may include custom hardware and may issue commands (e.g., motion control) to the S/As <NUM>-<NUM>, and may receive sensor inputs (e.g., position data, etc.) from the S/As <NUM>-<NUM> in real-time. The various PLCs <NUM>-<NUM> may also coordinate with each other with respect to S/A control. In an example, the S/As <NUM>-<NUM> may include rotary motors, linear servomotors and/or position sensors.

Table <NUM> (below) depicts example PLC communication parameters for the CoMP network <NUM>:.

In a particular example, traffic between the PLCs <NUM>-<NUM> and the S/As <NUM>-<NUM> may include mission-critical traffic and non-critical traffic. Most mission-critical traffic occurs periodically, whereas non-critical traffic generally occurs aperiodically. In a particular factory example, a network of distributed PLCs may define between <NUM>-<NUM> cells (e.g., scalable based on a size of the factory) with a cell size of 10x10x3m, with each cell supporting <NUM>-<NUM> nodes (e.g., S/As, HMIs, etc.).

Referring to <FIG>, the CoMP network <NUM> may correspond to an example implementation of the RAT system <NUM> of <FIG>, whereby the S/As <NUM>-<NUM> and HMIS <NUM>-<NUM> are example implementations of the UE <NUM> and the PLCs <NUM>-<NUM> are example implementations of the BS <NUM> of the RAT system <NUM> of <FIG>.

As noted above, certain mission-critical traffic between the PLCs <NUM>-<NUM> and the S/As <NUM>-<NUM> may reliably occur on a periodic basis. For example, the S/As <NUM>-<NUM> may periodically report mission-critical sensor feedback to the PLCs <NUM>-<NUM>, and the PLCs <NUM>-<NUM> may periodically transmit mission-critical control data to the S/As <NUM>-<NUM>.

<FIG> illustrates a CoMP network 700B in accordance with another embodiment of the disclosure. In particular, the CoMP network 700B illustrates a more detailed implementation example of the CoMP network <NUM> of <FIG>.

Referring to <FIG>, a first zone ("Zone A") includes a PLC 705B, a local radio coordinator 710B, and S/As 715B-720B and a second zone ("Zone B") includes a PLC 725B, a local radio coordinator 730B, and S/As 735B-740B. Each of the local radio coordinators 710B-730B is communicatively coupled to a global radio coordinator 745B via an LTE link. Inside each zone, the various communication devices communicate wirelessly via respective low-latency wireless communication links (e.g., Bluetooth, ZigBee, URLLC, etc.). In an example, the local radio coordinators 710B-730B and global radio coordinator 745B may collectively correspond to the management system <NUM> in <FIG>.

<FIG> illustrates a timing diagram for communications between a master device and N slave devices in accordance with an embodiment of the disclosure. <FIG> illustrates logical connections of a physical channel for the communications shown in <FIG> in accordance with an embodiment of the disclosure. In an example, the master device may correspond to one of the PLCs described above with respect to <FIG>, and the N slave devices may each correspond to one of the S/As described above with respect to <FIG>. In <FIG>, the master device (denoted as master device <NUM>) includes an application that is logically connected to a slave device (denoted as slave device <NUM>), whereby the end-to-end communication over a physical channel <NUM> is required to satisfy certain master-slave communication parameters (denoted as L, Tcyc, Tv, PLR and J).

Referring to <FIG>, the master device and N slave devices may communicate with each other in cycles (referred to herein as traffic cycles), whereby Tcyc denotes the traffic cycle duration. Generally, the master device sends commands at the beginning of each traffic cycle (e.g., in a window of time denoted as Tv), and the N slave devices respond back to the master device (e.g., with measurements, etc.) before the end of the traffic cycle.

Table <NUM> (below) depicts example master-slave communication parameters between a master device and various types of slave devices:.

Various issues may arise with certain publicly available solutions for mission-critical communications, for example, in the factory automation space. For example, existing solutions may use the crowded unlicensed band, leading to unpredictable interference, limited transmission power, and stringent listen-before-talk requirements. Other solutions may emphasize energy efficiency at the cost of unacceptable latency. One solution, which uses current 3GPP agreements, carries heavy control signaling overhead, a reliability target of 10e-<NUM> to 10e-<NUM>, and is currently usable only in frequency division duplexing (FDD). Furthermore, such a solution may use a grant-free approach, which may lead to collisions in dense deployments, such as factory floors.

Some techniques and apparatuses described herein provide opportunistic reassignment of persistent resource allocations for communications, such as mission-critical communications. For example, some techniques and apparatuses described herein provide low latency and high reliability for communications using limited control signaling (e.g., without initial scheduling using a PDCCH) in FDD or TDD, overprovisioning to improve reliability, and an acknowledgment/negative acknowledgment procedure to indicate success or failure of an overprovisioned communication. In this way, a reliable, low-latency wireless communication structure can be achieved for mission-critical communications, such as factory automation communications.

<FIG> is a diagram illustrating an example <NUM> of opportunistic retransmission of mission-critical communications, in accordance with various aspects of the present disclosure. <FIG> shows a BS <NUM>, which is a scheduling entity for a UE <NUM>-<NUM> and a UE <NUM>-<NUM>. However, in some aspects, a UE may be a scheduling entity for one or more other UEs <NUM>.

As shown in <FIG>, and by reference number <NUM>, the UE <NUM>-<NUM> may perform a first communication with the BS <NUM> based at least in part on a persistent resource allocation. As used herein, persistent resource allocation may be implemented via any well-known semi-persistent scheduling (SPS) protocol. For example, the first communication may be an uplink communication and/or a downlink communication. The persistent resource allocation may identify repeating resources in which the first communication is to be performed. In some aspects, the repeating resources may be in a single channel, although other implementations are possible (e.g., different channels, frequency hopping, etc.). In some aspects, the first communication may be a first transmission or reception, and one or more additional resources in a subsequent channel may be allocated for the first communication. When the first transmission or reception of the first communication is successful, the one or more additional resources may be used for other communications, as described below. When the first transmission or reception is unsuccessful, a second transmission or reception (e.g., a repetition) of the first communication may be performed in the one or more additional resources. For a more detailed description of the persistent resource allocation, refer to the description of <FIG>, below.

In some aspects, the UE <NUM>-<NUM> may be associated with another persistent resource allocation. For example, UEs <NUM>-<NUM> and <NUM>-<NUM> may be associated with respective resource allocations, which reduces collision of communications of UEs <NUM>-<NUM> and <NUM>-<NUM> with each other or communications of other UEs <NUM>. In some aspects, the techniques described herein may be applied in dense deployments of, for example, tens of UEs, hundreds of UEs, and/or the like. In this way, the persistent resource allocation increases a practical limit on the number of UEs that can be deployed in an area. In some aspects, the persistent resource allocations may be pre-configured or predefined before the operations described in connection with <FIG>. For example, the persistent resource allocations may not be provided to the UE <NUM>-<NUM> and <NUM>-<NUM> using physical downlink control channels as the communications are performed, which improves reliability and reduces messaging overhead of the BS <NUM>.

As shown by reference number <NUM>, the BS <NUM> may determine that the first communication is successful. When the first communication is a downlink communication, the BS <NUM> may determine that the first communication is successful based at least in part on receiving an ACK from the UE <NUM>-<NUM>. When the first communication is an uplink communication, the BS <NUM> may determine that the first communication is successful based at least in part on decoding the first communication, and may provide an ACK to the UE <NUM>-<NUM>. In some aspects, the BS <NUM> may determine that the first communication is successful after two or more repetitions of the first communication. For example, the UE <NUM> or BS <NUM> may combine the two or more repetitions until a successful result is reached, and may provide an ACK after the successful result is reached.

As shown by reference number <NUM>, the BS <NUM> schedules a resource of the persistent resource allocation of the UE <NUM>-<NUM> for a second UE (e.g., UE <NUM>-<NUM>). In this way, subsequent resources of the persistent resource allocation are not wasted after the first communication is successfully decoded. In some aspects, the BS <NUM> may select a UE or a communication to receive the resource. For example, in a situation wherein the BS <NUM> is a scheduling entity for many UEs <NUM> (i.e., greater than a threshold number of UEs <NUM>), the BS <NUM> may select a UE <NUM> and/or a communication of the UE <NUM> for which the resource is to be reassigned (e.g., based at least in part on a UE-specific priority or a communication-specific priority, such as a communication with a highest number of unsuccessful attempts, etc.).

As shown by reference number <NUM>, the BS <NUM> may provide a downlink control channel, such as a physical downlink control channel (PDCCH), to the UE <NUM>-<NUM>. The PDCCH may include a grant for the resource from the persistent resource allocation of the UE <NUM>-<NUM>. In this way, the resource is reallocated from the persistent resource allocation based at least in part on a need of another UE. In some aspects, the resource from the persistent resource allocation of the UE <NUM>-<NUM> may be frequency hopped when reassigned to the UE <NUM>-<NUM>. This may improve frequency diversity of the second communication.

As shown by reference number <NUM>, the UE <NUM>-<NUM> performs a second communication using the resource from the persistent resource allocation. In some aspects, the second communication may be an uplink communication and/or a downlink communication. The UE <NUM>-<NUM> performs the second communication using the resource in addition to, or, in some non-limiting aspects, alternatively to, performing the second communication using a resource of a persistent resource allocation of the UE <NUM>-<NUM>. In this way, resilience of the second communication is improved.

In some aspects, the first communication and/or the second communication may include mission-critical traffic. For example, the first communication and/or the second communication may include cyclical data for a factory automation environment. Therefore, the dynamic reallocation of resources of persistent resource allocations for the first communication and the second communication may be particularly beneficial (e.g., since the cyclical nature of the communications improves predictability of the communications).

<FIG> is a diagram illustrating examples <NUM> of uplink and downlink communication structures for opportunistic retransmission of mission-critical communications, in accordance with various aspects of the present disclosure.

In <FIG>, a downlink resource allocation technique is described in connection with reference numbers <NUM>-<NUM>. As can be seen, the downlink resource allocation technique may use the DL-centric subframe structure described in connection with <FIG>, above. Furthermore, an uplink resource allocation technique is described in connection with reference numbers <NUM>-<NUM>. As can also be seen, the uplink resource allocation technique may use the UL-centric subframe structure described in connection with <FIG>, above.

As shown, UEs <NUM> through N (e.g., UEs <NUM>) may receive first communications in a downlink data portion of a first slot <NUM>. In <FIG>, a particular UE (e.g., UE <NUM>) receives or transmits a communication in a resource in which the name of the particular UE is shown. For example, UE <NUM>, UE <NUM>, and UE N each receives a communication in the first slot <NUM> (e.g., the names of UEs <NUM>, <NUM>, and N are shown in the downlink data portions of the first slot <NUM>).

As shown by reference number <NUM>, UEs <NUM> through N may provide ACKs or NACKs regarding the first communications in the uplink short burst portion of the DL-centric subframe. By providing the ACKs or NACKs <NUM>, the UEs <NUM> through N may enable opportunistic reassignment of the resources of the second slot (e.g., second slot <NUM>, described below) for retransmission of unsuccessful first communications, as described below. As used herein, a NACK may refer to an explicit NACK where the UE transmits a NACK signal that successfully arrives at the BS <NUM>, or alternatively to an implicit NACK where the BS <NUM> simply does not receive any ACK or NACK from the BS <NUM> in a defined period of time (e.g., irrespective of whether the UE attempted to transmit an ACK or NACK).

As shown by reference number <NUM>, the UE N provides an ACK (shown as A) for the first communication of the UE N. This may mean that the UE N successfully decoded the first communication. As shown by reference number <NUM>, the UEs <NUM> and <NUM> provide a NACK (shown as N, which may correspond to either an explicit NACK or an implicit NACK) for the first communications of the UE <NUM> and the UE <NUM>. In some aspects, a UE may provide additional information with an ACK or NACK, such as updated channel state information, a desired modulation and coding scheme (MCS) for a second communication, or other information.

<FIG> describes a time division duplexing (TDD) implementation of the opportunistic reallocation techniques described herein. In some aspects, the opportunistic reallocation techniques described herein can be implemented using FDD. For example, in FDD, a UE may provide an ACK or NACK in an allocated ACK/NACK uplink or downlink resource.

As shown, UEs <NUM> and <NUM> may perform second communications in a second slot <NUM>. For example, the UEs <NUM> and <NUM> may be assigned their respective resources based at least in part on persistent resource allocations of the UEs <NUM> and <NUM>.

As shown by reference number <NUM>, a resource that would otherwise be assigned to the UE N based at least in part on a persistent resource allocation of the UE N may be assigned to the UE <NUM>. For example, the resource may be assigned to the UE <NUM> since the UE <NUM> was not successful in decoding the first communication (e.g., based at least in part on the NACK shown in connection with reference number <NUM>). The UE <NUM> may receive a second communication in the resource. For example, the second communication may include a partial or complete retransmission of the first communication, and/or may include other information. As further shown, the UEs <NUM> and <NUM> provide ACKs for the second communications, meaning that decoding of the second communications is successful. In this way, resilience of, for example, mission-critical traffic is improved.

As further shown, on the uplink, UEs <NUM> through N may transmit a first communication in a first slot <NUM>. A scheduling entity (e.g., a BS <NUM>, a UE <NUM>, a PLC, or a similar device) may provide an ACK or a NACK for the first communications of the UEs <NUM> through N in a downlink resource, such as a PDCCH. Here, the UEs <NUM> and N receive NACKs and the UE <NUM> receives an ACK.

As further shown, in a second slot <NUM>, a resource or channel previously used for the UE <NUM> may be allocated for the UE <NUM>. For example, the scheduling entity may provide scheduling information in the PDCCH shown by reference number <NUM> when the scheduling entity provides the ACK or NACK. The UE <NUM> may transmit a second communication (e.g., a partial or complete retransmission of the first communication and/or other information) using a persistent resource allocation of the UE <NUM> and a resource previously allocated for the UE <NUM> in the second slot <NUM>. In this way, a resource of a persistent resource allocation of the UE <NUM> is opportunistically reassigned for the UE <NUM>, which improves reliability and coverage of the UEs <NUM> through N.

While the techniques described in connection with <FIG> are described with reference to two consecutive slots and three UEs, the techniques described herein are not so limited. For example, the techniques and apparatuses described herein can be applied with regard to any number of UEs (e.g., tens of UEs, hundreds of UEs, etc.) and over any length of time and/or any number of slots.

In this way, a combination of persistent resource allocation for predictable communications and opportunistic reassignment of resources of the persistent resource allocation is performed. This may provide an advantage over a fixed resource allocation such as a circuit-switched system, since resources that are not needed by one UE can be dynamically reassigned for use by another UE. Furthermore, this may provide an advantage over a purely grant-based system, since downlink grant information (e.g., PDCCH) inherently uses significant overhead and may not achieve desired reliability levels. For example, by using PDCCH signaling only for re-allocation, and not for initial allocation or other control signaling, resources may be saved and reliability may be improved. Furthermore, the techniques and apparatuses described herein may be useful for cyclic traffic associated with relatively small payloads (e.g., approximately <NUM> to <NUM> bytes), such as mission-critical traffic for factory automation, although the techniques and apparatuses described herein are not necessarily limited to such an implementation.

In <FIG>, a separate PDCCH is sent for each UE that NACKs the first communication from slot <NUM> in order to reassign a persistent resource for the second communication in slot <NUM> from another UE that ACKed the first communication from slot <NUM>. For example, UE N ACKs (<NUM>) the first communication in the first slot, after which a PDCCH is sent which reassigns UE N's resource to UE <NUM> for the second communication (<NUM>) in slot <NUM>. Each PDCCH carries a Downlink Control Indicator (DCI) that can have <NUM>+ bits. To achieve a high reliability (e.g., 10e-<NUM>), the DCI in each PDCCH may further include a high number of Cyclic Redundancy Check (CRC) bits (e.g., <NUM> CRC bits per each <NUM> bit DCI) and a higher Aggregation Level (AL) (e.g., in LTE, AL <NUM> may be used for the PDCCHs, out of available ALs of <NUM>, <NUM>, <NUM> and <NUM>, whereby the AL indicates the number of required Control Channel Elements (CCEs) for the PDCCH DCI).

In an example with reference to <FIG>, assume that N=<NUM> such that there are <NUM> UEs (e.g., S/As). The first communication in slot <NUM> is based on previously established SPS-based resource assignment, such that there is no PDCCH constraint for the first communication in slot <NUM>. Now, assume that <NUM> UEs ACK the first communication in slot <NUM>, while <NUM> UEs NACK the first communication in slot <NUM>. The <NUM> UEs that NACK the first communication in slot <NUM> require retransmission of their respective communications in slot <NUM>, such that <NUM> PDCCHs are transmitted to these <NUM> UEs, requiring a total of <NUM>+ bits (out of which <NUM> bits are CRC bits). In particular, if each PDCCH requires AL <NUM> for higher reliability, the number of resource blocks (RBs) can be <NUM>*(<NUM>+<NUM>)*<NUM>/<NUM> = <NUM>, which may exceed PDCCH capacity.

Accordingly, embodiments of the disclosure are further directed to a Group PDCCH (G-PDCCH) for more efficient reassignment of downlink SPS-based resources.

<FIG> illustrates an example of opportunistic retransmission in accordance with various aspects of the present disclosure. In <FIG>, reference is made to BS <NUM> and UEs <NUM>. In an example, the BS <NUM> may correspond to a PLC (e.g., a gNB) and each of the UEs <NUM>. N may correspond to an S/A.

Referring to <FIG>, at block <NUM>, BS <NUM> assigns resources <NUM>. N to UEs <NUM>. N, respectively, via an SPS-based protocol. Accordingly, resources <NUM>. N are assigned to UEs <NUM>. N as persistent resources. As an example, each assigned resource among resources <NUM>. N may correspond to a resource block (RB).

At block <NUM>, the BS <NUM> conveys at least one resource reallocation scheme for retransmissions to each of UEs <NUM>. Each resource reallocation scheme permits each of UEs <NUM>. N to identify how resources <NUM>. N are distributed among a subset of the UEs <NUM>. N for a communication retransmission based on information contained in a G-PDCCH, as will be described in more detail below. In an example, the at least one resource reallocation scheme may include a single resource reallocation scheme or multiple resource reallocation schemes. If multiple resource reallocation schemes are provided, the G-PDCCH may identify a particular one of the multiple resource reallocation schemes to be used. Various examples of resource reallocation schemes are described below in more detail.

At block <NUM>, the BS <NUM> transmits a first communication to UEs <NUM>. N on resources <NUM>. N, respectively. In an example, the transmission at block <NUM> may occur without the use of a PDCCH based on the persistent scheduling of these particular resources. In a further example, for a TDD implementation, the first communications may be transmitted in a first slot, such as first slot <NUM> in <FIG>. Further, the first communications to the respective UEs may include the same data or different data.

Referring to <FIG>, UEs <NUM> and <NUM> fail to successfully decode their respective first communications, such that UEs <NUM> and <NUM> each transmit a NACK to the BS <NUM> at blocks <NUM>-<NUM>. By contrast, UEs <NUM>. N each successfully decode their respective first communications, such that UEs <NUM>. N each transmit an ACK to the BS <NUM> at block <NUM>.

At block <NUM>, the BS <NUM> configures a G-PDCCH to indicate an allocation of resources <NUM>. N to UEs <NUM> and <NUM> for retransmission of the first communications to UEs <NUM> and <NUM> based on one of the resource reallocation schemes from block <NUM>. Because the resource reallocation scheme(s) are coordinated in advance of the G-PDCCH transmission, the resource reallocation scheme(s) may be characterized as "predetermined" resource reallocation scheme(s). If only one predetermined resource reallocation scheme is established at block <NUM>, the predetermined resource reallocation scheme need not be expressly identified in the G-PDCCH. However, if multiple resource reallocation schemes are established at block <NUM>, a particular resource reallocation scheme may be identified by the G-PDCCH.

In an example, the G-PDCCH may include a single DCI with a single set of CRC bits, in contrast to the UE-specific PDCCHs described above with respect to <FIG> whereby each target UE for the PDCCH includes a separate DCI (e.g., <NUM> CRC bits per DCI). Assuming <NUM> CRC bits per DCI, sending two PDCCHs to UEs <NUM> and <NUM> requires <NUM> bits in accordance with <FIG>, whereas a G-PDCCH only requires <NUM> CRC bits.

It will be further appreciated that the CRC bit savings associated with the G-PDCCH will scale with the number of UEs that NACK the first communication. For example, consider a deployment whereby there are <NUM> total UEs (N=<NUM>), with <NUM> UEs ACKing the first communication and <NUM> UEs NACKing the first communication. Using Binary Phase Shift Keying (BPSK), each UE ID requires <NUM> bits. The G-PDCCH DCI payload = <NUM> x <NUM> + <NUM>[CRC] = <NUM> bits. Assuming AL=<NUM>, the G-PDCCH size = <NUM> x <NUM> = <NUM> resource elements (REs). By contrast, the total separate NR PDCCH size for sending <NUM> separate PDCCHs is (<NUM>[DCI] + <NUM>[CRC])*<NUM>*<NUM> = <NUM> REs.

Returning to <FIG>, the G-PDCCH is then transmitted at block <NUM> (e.g., at a beginning of a second slot for a TDD implementation, such as the second slot <NUM> in <FIG>).

At block <NUM>, UEs <NUM>. N simply ignore the G-PDCCH because the UEs <NUM>. N already successfully decoded their respective first communications at block <NUM>. By contrast, at blocks <NUM>-<NUM>, UEs <NUM> and <NUM> each decode the G-PDCCH and identify the resources to be used for retransmission. As will be described below in more detail, the identification of the retransmission resources at blocks <NUM>-<NUM> is based on the predetermined resource reallocation scheme(s) established earlier at block <NUM>.

At block <NUM>, the BS <NUM> transmits a second communication to UEs <NUM> and <NUM> on resources <NUM>. N, respectively. In particular, the second communications transmitted to UEs <NUM> and <NUM> at block <NUM> are retransmissions of the first communications transmitted to UEs <NUM> and <NUM> at block <NUM>. The distribution of the resources <NUM>. N allocated between UEs <NUM> and <NUM> is mapped in accordance with one of the predetermined resource reallocation scheme(s) established at block <NUM> as indicated by the G-PDCCH at block <NUM>. Further, the second communications to the respective UEs <NUM> and <NUM> may include the same data or different data.

At block <NUM>, UEs <NUM>. N simply ignore the transmission of block <NUM> because the UEs <NUM>. N already successfully decoded their respective first communications at block <NUM>. By contrast, at blocks <NUM>, UEs <NUM> and <NUM> each successfully decode their respective second communications, such that UEs <NUM> and <NUM> each transmit an ACK to the BS <NUM> at blocks <NUM> and <NUM>.

Examples of resource reallocation schemes for the second communication transmissions are shown in Table <NUM> (below):.

Referring to Table <NUM>, assume the following:.

Under these assumptions, resource reallocation scheme #<NUM> assigns, for the second communication, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, and RB rows <NUM>. <NUM> to UE <NUM>, i.e., in proportion to the total available RB rows in the listed UE order from the G-PDCCH.

Under these assumptions, resource reallocation scheme #<NUM> assigns, for the second communication, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, and RB rows <NUM>. <NUM> to UE <NUM>, i.e., in proportion to the total available RB rows in the reverse of the listed UE order from the G-PDCCH.

Under these assumptions, resource reallocation scheme #<NUM> assigns, for the second communication, RB rows <NUM>. <NUM> to UE <NUM> based on the increased priority allocated to the first-listed UE. Then, resource reallocation scheme #<NUM> assigns RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, RB rows <NUM>. <NUM> to UE <NUM>, and RB rows <NUM>. <NUM> to UE <NUM>, i.e., half of the RB rows to the first-listed UE, with the remaining RB rows allocated in proportion to the total available RB rows in the listed UE order from the G-PDCCH. Also, any RB row remainder goes to the last-listed UE in this example, although the RB row remainder can be handled in other ways in accordance with other implementations of resource reallocation scheme #<NUM> (e.g., tacked onto the RB rows allocated to the first-listed UE so that UE <NUM> is assigned RB rows <NUM>. <NUM> with the remaining UEs being assigned an even <NUM> RB rows each, etc.).

In an example, it is possible for two or more of the resource reallocation schemes to be coordinated between the BS <NUM> and UEs <NUM>. N in <FIG>. In this case, each of the two or more resource reallocation schemes may be indexed to a unique resource reallocation scheme identifier. The G-PDCCH may then be configured with a field containing the resource reallocation scheme identifier that identifies the resource reallocation scheme to be used in the transmission of the second communications to ensure that each target UE tunes to the correct resources.

For implementations where the G-PDCCH is required to include the UE IDs of each UE being assigned resources for transmission of the second communications (e.g., as in resource reallocation schemes #<NUM>-#<NUM> in Table <NUM> above), it will be appreciated that the size of the G-PDCCH is variable and scales with the number of UE IDs to be included in the G-PDCCH. However, in certain implementations, the UEs may need to know the G-PDCCH size in advance to properly decode the G-PDCCH. Various mechanisms can be implemented to convey the G-PDCCH size to the UEs in advance of the G-PDCCH transmission, such as any of the following:.

<FIG> and <FIG> illustrate opportunistic retransmission procedures <NUM> and <NUM> in accordance with embodiments of the disclosure. In an example, the opportunistic retransmission procedure <NUM> of <FIG> is performed by a BS, such as BS <NUM> (e.g., a gNB, PLC, TRP, etc.), whereas the opportunistic retransmission procedure <NUM> of <FIG> is performed by a UE, such as UE <NUM>, S/A, etc.). In particular, the BS performing the process of <FIG> may correspond to the BS <NUM> in the process of <FIG>, and the UE performing the process of <FIG> may correspond to UE <NUM> or UE <NUM> in the process of <FIG>.

Referring to <FIG>, at block <NUM>, the BS transmits, on a set of resources, a first communication to each of a plurality of UEs. For example, the set of resources may correspond to a group of resource blocks or resource elements on a downlink channel, as in block <NUM> of <FIG>. At block <NUM>, the BS receives ACKs to the transmitted first communications from a first subset of the plurality of UEs (e.g., UEs <NUM>. N at block <NUM> of <FIG>). At block <NUM>, the BS determines that a second subset of the plurality of UEs (e.g., UEs <NUM> and <NUM> at blocks <NUM>-<NUM> of <FIG>) has failed to acknowledge the transmitted first communications (e.g., based on receipt of express NACKs and/or by interpreting a failure to respond to the transmitted first communications as an implicit NACK). At block <NUM>, the BS configures a group scheduling message that indicates an allocation of the set of resources to the second subset of UEs based on a predetermined resource reallocation scheme (e.g., as in block <NUM> of <FIG>). At block <NUM>, the BS transmits the group scheduling message to the second subset of UEs (e.g., as in block <NUM> of <FIG>). At block <NUM>, the BS transmits, on the set of resources, a second communication to each UE in the second subset of UEs in accordance with the indicated allocation from the group scheduling message (e.g., as in block <NUM> of <FIG>).

At block <NUM>, the UE receives, from the BS, a group scheduling message that indicates an allocation of a set of resources to a subset of a plurality of UEs that each failed to acknowledge a respective first communication among a plurality of first communication transmissions from the base station, the indicated allocation of the set of resources being based on a predetermined resource reallocation scheme (e.g., the transmission from block <NUM> of <FIG>). At block <NUM>, the UE determines, from the indicated allocation of the set of resources in the group scheduling message, a subset of the set of resources allocated to the UE (e.g., one of the transmissions from block <NUM> of <FIG>). At block <NUM>, the UE receives, from the BS, a second communication on the subset of resources allocated to the UE (e.g., one of the transmissions from block <NUM> of <FIG>).

In an example, the failure of the plurality of UEs (including the UE performing the process of <FIG>) to acknowledge their respective first communication can occur in different ways. For example, a UE may fail to acknowledge its respective first communication by successfully transmitting an explicit NACK from the UE to the base station, or by failing to successfully transmit either a NACK or an ACK from the UE to the base station (i.e., an implicit NACK). Moreover, an implicit NACK may occur based on a failure on the downlink side (e.g., the first communication fails to reach the UE at all) or the uplink side (e.g., the first communication reaches the UE, but the UE's ACK or NACK to the first communication fails to reach the BS).

It will be appreciated that the process <NUM> of <FIG> represents an example implementation of the processes <NUM>-<NUM> in <FIG>. The NACKs received at the BS in <FIG> and/or conveyed by the UE in <FIG> may include at least one explicit NACK, at least one implicit NACK, or a combination thereof. The processes <NUM>-<NUM> of <FIG> may be preceded by negotiation or establishment of one or more resource reallocation schemes, for example, as described with respect to block <NUM> of <FIG>. If multiple resource reallocation schemes, the group scheduling message (e.g., G-PDCCH) may include a field that identifies the predetermined resource reallocation scheme. The group scheduling message (e.g., G-PDCCH) may include a UE ID of each UE that NACKs the first communication, and the predetermined resource reallocation scheme may allocate the set of resources between the subset of UEs that NACK the first communication based at least in part upon an order in which the UE IDs are listed in the group scheduling message. The group scheduling message may be configured with a fixed size, or alternatively may have a variable size that scales with the number of UEs that NACK the first communication, with the variable size being conveyed from the BS to the UE before the group scheduling message (e.g., G-PDCCH) is transmitted.

It should be understood that any reference to an element herein using a designation such as "first," "second," and so forth does not generally limit the quantity or order of those elements. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. Also, unless stated otherwise a set of elements may comprise one or more elements. In addition, terminology of the form "at least one of A, B, or C" or "one or more of A, B, or C" or "at least one of the group consisting of A, B, and C" used in the description or the claims means "A or B or C or any combination of these elements. " For example, this terminology may include A, or B, or C, or A and B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so on.

In view of the descriptions and explanations above, one skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both.

Accordingly, it will be appreciated, for example, that an apparatus or any component of an apparatus may be configured to (or made operable to or adapted to) provide functionality as taught herein. This may be achieved, for example: by manufacturing (e.g., fabricating) the apparatus or component so that it will provide the functionality; by programming the apparatus or component so that it will provide the functionality; or through the use of some other suitable implementation technique. As one example, an integrated circuit may be fabricated to provide the requisite functionality. As another example, an integrated circuit may be fabricated to support the requisite functionality and then configured (e.g., via programming) to provide the requisite functionality. As yet another example, a processor circuit may execute code to provide the requisite functionality.

Moreover, the methods, sequences, and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random-Access Memory (RAM), flash memory, Read-only Memory (ROM), Erasable Programmable Read-only Memory (EPROM), Electrically Erasable Programmable Read-only Memory (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art, transitory or non-transitory. In the alternative, the storage medium may be integral to the processor (e.g., cache memory).

Accordingly, it will also be appreciated, for example, that certain aspects of the disclosure can include a transitory or non-transitory computer-readable medium embodying a method for communication.

Claim 1:
A method of operating a base station of a communications network, comprising:
transmitting (<NUM>), on a set of resources, a first communication to each of a plurality of user equipments, UEs;
receiving (<NUM>) acknowledgments, ACKs, to the transmitted first communications from a first subset of the plurality of UEs;
determining (<NUM>) that a second subset of the plurality of UEs has failed to acknowledge the transmitted first communications;
configuring (<NUM>) a group scheduling message that indicates an allocation of the set of resources to the second subset of UEs based on a predetermined resource reallocation scheme;
transmitting (<NUM>) the group scheduling message to the second subset of UEs; and
transmitting (<NUM>), on the set of resources, a second communication to each UE in the second subset of UEs in accordance with the indicated allocation from the group scheduling message;
wherein at least one resource of the set of resources, associated with transmission of a respective transmitted first communication to a first respective UE among the first subset of UEs, is associated with transmission of a respective transmitted second communication to a second respective UE among the second subset of UEs; and
wherein at least one additional resource of the set of resources, associated with transmission of a respective transmitted first communication to the second respective UE, is associated with transmission of the respective transmitted second communication to the second respective UE.