Patent Description:
Wireless communication systems are rapidly growing in usage. In recent years, wireless devices such as smart phones and tablet computers have become increasingly sophisticated. In addition to supporting telephone calls, many mobile devices (i.e., user equipment devices or UEs) now provide access to the internet, email, text messaging, and navigation using the global positioning system (GPS), and are capable of operating sophisticated applications that utilize these functionalities. Additionally, there exist numerous different wireless communication technologies and standards. Some examples of wireless communication standards include GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE Advanced (LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), IEEE <NUM> (WLAN or Wi-Fi), IEEE <NUM> (WiMAX), BLUETOOTH™, etc. A proposed next telecommunications standards moving beyond the current International Mobile Telecommunications-Advanced (IMT-Advanced) Standards is called 5th generation mobile networks or 5th generation wireless systems, referred to as 3GPP NR (otherwise known as <NUM>-NR for <NUM> New Radio, also simply referred to as NR). NR proposes a higher capacity for a higher density of mobile broadband users, also supporting device-to-device, ultra-reliable, and massive machine communications, as well as lower latency and lower battery consumption, than current LTE standards.

The ever increasing number of features and functionality introduced in wireless communication devices also creates a continuous need for improvement in both wireless communications and in wireless communication devices. In particular, it is important to ensure the accuracy of transmitted and received signals through user equipment (UE) devices, e.g., through wireless devices such as cellular phones, base stations and relay stations used in wireless cellular communications. In many instances, modern wireless communications networks use MIMO (multiple-in-multiple-out) technology to achieve high data rates. One MIMO technique is beamforming, which permits targeted illumination of specific areas, making it possible to improve transmission to users at the far edges of cellular coverage. Many wireless communications standards such as WLAN and WiMAX™, LTE and NR incorporate beamforming among their many features. Beamforming is particularly important for the time division duplex (TDD) mode in LTE and NR.

Transmit beamforming uses multiple antennas to control the direction of a wave(front) by appropriately weighting the magnitude and phase of individual antenna signals. This makes it possible to provide better coverage to specific areas along the cell edges, with every antenna in the array contributing to the steered signal, thereby achieving an array gain, also referred to as a beamforming gain. Receive beamforming makes it possible to determine the direction from which the wave(front) arrives, and suppress selected interfering signals by applying a beam pattern null in the direction of the interfering signal. Adaptive beamforming is a technique for continually applying beamforming to a moving receiver, which typically requires rapid signal processing and powerful algorithms.

Analog/digital hybrid beamforming is enabled by smaller antenna element size and thus features prominently in at least NR wireless communications. Beam management is important to combat propagation loss for reliable communications, especially for millimeter wave (mmWave) systems. Part of beam management involves the communication of beamforming information (e.g. a beam indication) between wireless communication devices, for example between user equipment devices (UEs) and cellular base stations. While various present day beamforming structures and methods of communicating beam indication (beamforming information) have proven reliable under various conditions, there is room for improvement in how beamforming structures are defined and beam indication information is transmitted/received for devices performing frequent data transmissions in a rapidly changing environment.

Other corresponding issues related to the prior art will become apparent to one skilled in the art after comparing such prior art with the disclosed embodiments as described herein. <CIT> relates to devices and methods of beamforming. A UE transmits to an eNB a BRSRP report having selected BRSRP values and associated BRS IDs. An active link list, a CSI resource indication, and a first active link are used to measure the CSI resource and CSI feedback is sent. A serving link ID is provided to indicate a second active link to use for control and data reception. Rx beams are trained based on multiple instances of each BRS and the eNB supplies selection criteria for the BRSRP report. The Rx beams are refined based on BRRS and the second active link is dependent on BRRSRP or CSI feedback. When configured for dual beam operation, the BRSRP feedback corresponds to BRSRP value pairs and dual Rx beams associated with a pair of serving link IDs are used. <NPL>, discusses issues related to beam indication for downlink data channel. <NPL>, discusses issues related to beam reporting and beam indication mechanism for DL transmissions. <NPL>, discusses details of multi-beam control operation. <NPL>, relates to SS-block beam management, beam indication, and beam reporting. <NPL>, relates to beam management and overhead reduction of beam indication in a hierarchical structure of the control and data channels.

Embodiments are presented herein of, inter alia, of methods for implementing transmission of a beam indication (or beam/QCL (quasi co-location) indication) and a hierarchical beamforming structure that improve wireless communication device (UE) mobility and reduce network traffic overhead during wireless communications, for example during 3GPP New Radio (NR) communications. Embodiments are further presented herein for wireless communication systems containing user equipment (UE) devices and/or base stations communicating with each other within the wireless communication systems. In some embodiments, the beam indication (or beam indication information or beamforming information) for a current physical data channel and a next physical control channel, e.g. for a current physical downlink shared channel (PDSCH) and a next physical data control channel (PDCCH), may be transmitted/carried as control information, e.g. in a downlink control information (DCI) element. The beam/QCL indication (information) in the DCI may provide an indication of transmit (TX) beamforming used by a base station. Upon receiving the beam indication (beam/QCL indication), the UE may determine which receive beamforming configuration to adopt to receive the current data channel and the next control channel (information). In other words, the UE may receive the current data and/or the next control channel according to beamforming performed based at least on the received beam (beam/QCL) indication.

Pursuant to the above, in some embodiments, DCI may be expanded to carry/transmit beam/QCL indications not only for a current physical data channel, but also for a next physical control channel, e.g. for GC-PDCCH and/or PDCCH. (As used herein, "GC-PDCCH and/or PDCCH" is also simply referred to as "GC-PDCCH/PDCCH", and "beam indication and/or QCL indication" is also simply referred to as "beam indication" or "beam/QCL indication").

In some embodiments, a base station (e.g. gNB) may wirelessly transmit, to a device, DCI carrying beamforming information that includes a beam indication representative of a hierarchical beamforming structure. The beam indication may be used by the device to derive, during a receive beam sweep/update, receive beams that correspond to higher order channels of multiple different channels from receive beams that correspond to lower order channels of the multiple different channels. For each respective channel of the multiple different channels, respective beams corresponding to the channel may occupy a corresponding hierarchical level of the hierarchical beamforming structure. In some embodiments, a beam resolution at the base station may increase monotonically for the multiple different channels organized in a high to low channel order, with the beam resolution increasing monotonically as the channel order decreases. In some embodiments, at least two beams corresponding to a first channel of the multiple different channels may have a same corresponding child beam, with the child beam corresponding to a second channel of the multiple different channels and occupying a lower hierarchical level of the hierarchical beamforming structure than the two beams. The DCI may include a TCI state field, with the beam indication provided in the TCI state field, and the number of bits used in the TCI state field corresponding to a number of beams supported for a physical data channel.

Note that the techniques described herein may be implemented in and/or used with a number of different types of devices, including but not limited to, base stations, access points, cellular phones, portable media players, tablet computers, wearable devices, and various other computing devices.

While features described herein are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to be limiting to the particular form disclosed, but on the contrary, the intention is to cover all modifications and alternatives falling within the scope of the subject matter as defined by the appended claims.

The following is a glossary of terms that may appear in the present application:.

<FIG> illustrates an exemplary (and simplified) wireless communication system, according to some embodiments. It is noted that the system of <FIG> is merely one example of a possible system, and embodiments may be implemented in any of various systems, as desired.

As shown, the exemplary wireless communication system includes a base station <NUM> which communicates over a transmission medium with one or more user devices 106A, 106B, etc., through 106N. Each of the user devices may be referred to herein as a "user equipment" (UE) or UE device. Various ones of the UE devices may implement a hierarchical beamforming structure, and transmission of beam/QCL (quasi co-location) indication information according to various embodiments disclosed herein.

The base station <NUM> may be a base transceiver station (BTS) or cell site, and may include hardware that enables wireless communication with the UEs 106A through 106N. The base station <NUM> may also be equipped to communicate with a network <NUM>, e.g., a core network of a cellular service provider, a telecommunication network such as a public switched telephone network (PSTN), and/or the Internet, neutral host or various CBRS (Citizens Broadband Radio Service) deployments, among various possibilities. Thus, the base station <NUM> may facilitate communication between the user devices and/or between the user devices and the network <NUM>. The communication area (or coverage area) of the base station may be referred to as a "cell. " It should also be noted that "cell" may also refer to a logical identity for a given coverage area at a given frequency. In general, any independent cellular wireless coverage area may be referred to as a "cell". In such cases a base station may be situated at particular confluences of three cells. The base station, in this uniform topology, may serve three <NUM> degree beam width areas referenced as cells. Also, in case of carrier aggregation, small cells, relays, etc. may each represent a cell. Thus, in carrier aggregation in particular, there may be primary cells and secondary cells which may service at least partially overlapping coverage areas but on different respective frequencies. For example, a base station may serve any number of cells, and cells served by a base station may or may not be collocated (e.g. remote radio heads). As also used herein, from the perspective of UEs, a base station may sometimes be considered as representing the network insofar as uplink and downlink communications of the UE are concerned. Thus, a UE communicating with one or more base stations in the network may also be interpreted as the UE communicating with the network, and may further also be considered at least a part of the UE communicating on the network or over the network.

The base station <NUM> and the user devices may be configured to communicate over the transmission medium using any of various radio access technologies (RATs), also referred to as wireless communication technologies, or telecommunication standards, such as GSM, UMTS (WCDMA), LTE, LTE-Advanced (LTE-A), LAA/LTE-U, <NUM>-NR (NR, for short), 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc. Note that if the base station 102A is implemented in the context of LTE, it may alternately be referred to as an 'eNodeB' or 'eNB'. Note that if the base station 102A is implemented in the context of <NUM> NR, it may alternately be referred to as 'gNodeB' or 'gNB'. In some embodiments, the base station <NUM> communicates with at least one UE, implementing a hierarchical beamforming structure, and transmission of beam/QCL (quasi co-location) indication information according to various embodiments disclosed herein. Depending on a given application or specific considerations, for convenience some of the various different RATs may be functionally grouped according to an overall defining characteristic. For example, all cellular RATs may be collectively considered as representative of a first (form/type of) RAT, while Wi-Fi communications may be considered as representative of a second RAT. In other cases, individual cellular RATs may be considered individually as different RATs. For example, when differentiating between cellular communications and Wi-Fi communications, "first RAT" may collectively refer to all cellular RATs under consideration, while "second RAT" may refer to Wi-Fi. Similarly, when applicable, different forms of Wi-Fi communications (e.g. over <NUM> vs. over <NUM>) may be considered as corresponding to different RATs. Furthermore, cellular communications performed according to a given RAT (e.g. LTE or NR) may be differentiated from each other on the basis of the frequency spectrum in which those communications are conducted. For example, LTE or NR communications may be performed over a primary licensed spectrum as well as over a secondary spectrum such as an unlicensed spectrum. Overall, the use of various terms and expressions will always be clearly indicated with respect to and within the context of the various applications/embodiments under consideration.

In some embodiments, base station 102A may be a next generation base station, e.g., a <NUM> New Radio (<NUM> NR) base station, or "gNB". In some embodiments, a gNB may be connected to a legacy evolved packet core (EPC) network and/or to a NR core (NRC) network. In addition, a gNB cell may include one or more transmission and reception points (TRPs).

As mentioned above, UE <NUM> may be capable of communicating using multiple wireless communication standards. For example, a UE <NUM> might be configured to communicate using any or all of a 3GPP cellular communication standard (such as LTE or NR) or a 3GPP2 cellular communication standard (such as a cellular communication standard in the CDMA2000 family of cellular communication standards). Base station <NUM> and other similar base stations operating according to the same or a different cellular communication standard may thus be provided as one or more networks of cells, which may provide continuous or nearly continuous overlapping service to UE <NUM> and similar devices over a wide geographic area via one or more cellular communication standards.

The UE <NUM> might also or alternatively be configured to communicate using WLAN, BLUETOOTH™, BLUETOOTH™ Low-Energy, one or more global navigational satellite systems (GNSS, e.g., GPS or GLONASS), one and/or more mobile television broadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible. Furthermore, the UE <NUM> may also communicate with Network <NUM>, through one or more base stations or through other devices, stations, or any appliances not explicitly shown but considered to be part of Network <NUM>. UE <NUM> communicating with a network may therefore be interpreted as the UE <NUM> communicating with one or more network nodes considered to be a part of the network and which may interact with the UE <NUM> to conduct communications with the UE <NUM> and in some cases affect at least some of the communication parameters and/or use of communication resources of the UE <NUM>.

Furthermore, as also illustrated in <FIG>, at least some of the UEs, e.g. UEs 106D and 106E may represent vehicles communicating with each other and with base station <NUM>, e.g. via cellular communications such as 3GPP LTE and/or <NUM>-NR communications, for example. In addition, UE 106F may represent a pedestrian who is communicating and/or interacting with the vehicles represented by UEs 106D and 106E in a similar manner.

<FIG> illustrates an exemplary user equipment <NUM> (e.g., one of the devices <NUM>-A through <NUM>-N) in communication with the base station <NUM> and an access point <NUM>, according to some embodiments. The UE <NUM> may be a device with both cellular communication capability and non-cellular communication capability (e.g., BLUETOOTH™, Wi-Fi, and so forth) such as a mobile phone, a hand-held device, a computer or a tablet, or virtually any type of wireless device. The UE <NUM> may be configured to communicate using any of multiple wireless communication protocols. For example, the UE <NUM> may be configured to communicate using two or more of CDMA2000, LTE, LTE-A, NR, WLAN, or GNSS. Other combinations of wireless communication standards are also possible.

The UE <NUM> may include one or more antennas for communicating using one or more wireless communication protocols according to one or more RAT standards. In some embodiments, the UE <NUM> may share one or more parts of a receive chain and/or transmit chain between multiple wireless communication standards. The shared radio may include a single antenna, or may include multiple antenFnas (e.g., for MIMO) for performing wireless communications. Alternatively, the UE <NUM> may include separate transmit and/or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As another alternative, the UE <NUM> may include one or more radios which are shared between multiple wireless communication protocols, and one or more radios which are used exclusively by a single wireless communication protocol. For example, the UE <NUM> may include a shared radio for communicating using either of LTE or CDMA2000 1xRTT or NR, and separate radios for communicating using each of Wi-Fi and BLUETOOTH™.

<FIG> illustrates a block diagram of an exemplary UE <NUM>, according to some embodiments. As shown, the UE <NUM> may include a system on chip (SOC) <NUM>, which may include portions for various purposes. For example, as shown, the SOC <NUM> may include processor(s) <NUM> which may execute program instructions for the UE <NUM> and display circuitry <NUM> which may perform graphics processing and provide display signals to the display <NUM>. The processor(s) <NUM> may also be coupled to memory management unit (MMU) <NUM>, which may be configured to receive addresses from the processor(s) <NUM> and translate those addresses to locations in memory (e.g., memory <NUM>, read only memory (ROM) <NUM>, NAND flash memory <NUM>) and/or to other circuits or devices, such as the display circuitry <NUM>, radio circuitry <NUM>, connector I/F <NUM>, and/or display <NUM>. The MMU <NUM> may be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU <NUM> may be included as a portion of the processor(s) <NUM>.

As shown, the SOC <NUM> may be coupled to various other circuits of the UE <NUM>. For example, the UE <NUM> may include various types of memory (e.g., including NAND flash <NUM>), a connector interface <NUM> (e.g., for coupling to the computer system), the display <NUM>, and wireless communication circuitry (e.g., for LTE, LTE-A, NR, CDMA2000, BLUETOOTH™, Wi-Fi, GPS, etc.). The UE device <NUM> may include at least one antenna (e.g. 335a), and possibly multiple antennas (e.g. illustrated by antennas 335a and 335b), for performing wireless communication with base stations and/or other devices. Antennas 335a and 335b are shown by way of example, and UE device <NUM> may include fewer or more antennas. Overall, the one or more antennas are collectively referred to as antenna(s) <NUM>. For example, the UE device <NUM> may use antenna(s) <NUM> to perform the wireless communication with the aid of radio circuitry <NUM>. As noted above, the UE may be configured to communicate wirelessly using multiple wireless communication standards in some embodiments.

As further described herein, the UE <NUM> (and/or base station <NUM>) may include hardware and software components for UE <NUM> to use a hierarchical beamforming structure, and receive beam/QCL indication(s) according to various embodiments disclosed herein. Thus, in some embodiments, UE <NUM> may perform beamforming according to a hierarchical beamforming, and may also receive a beam indication (or beam indication information or beamforming information) for a current physical data channel and a next physical control channel, e.g. for a current physical downlink shared channel (PDSCH) and a next PDCCH, as control information, e.g. in a downlink control information (DCI) element. The processor(s) <NUM> of the UE device <NUM> may be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, processor(s) <NUM> may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit). Specifically, processor(s) <NUM> may be coupled to and/or may interoperate with other components as shown in <FIG>, to implement communications by UE <NUM> that incorporate the hierarchical beamforming structure and the communicating of a beam/QCL indication according to various embodiments disclosed herein. Processor(s) <NUM> may also implement various other applications and/or end-user applications running on UE <NUM>.

In some embodiments, radio circuitry <NUM> may include separate controllers dedicated to controlling communications for various respective RAT standards. For example, as shown in <FIG>, radio circuitry <NUM> may include a Wi-Fi controller <NUM>, a cellular controller (e.g. LTE and/or NR controller) <NUM>, and BLUETOOTH™ controller <NUM>, and in at least some embodiments, one or more or all of these controllers may be implemented as respective integrated circuits (ICs or chips, for short) in communication with each other and with SOC <NUM> (and more specifically with processor(s) <NUM>). For example, Wi-Fi controller <NUM> may communicate with cellular controller <NUM> over a cell-ISM link or WCI interface, and/or BLUETOOTH™ controller <NUM> may communicate with cellular controller <NUM> over a cell-ISM link, etc. While three separate controllers are illustrated within radio circuitry <NUM>, other embodiments have fewer or more similar controllers for various different RATs that may be implemented in UE device <NUM>. For example, at least one exemplary block diagram illustrative of some embodiments of cellular controller <NUM> is shown in <FIG> as further described below.

The radio <NUM> may be designed to communicate via various wireless telecommunication standards, including, but not limited to, LTE, LTE-A, <NUM>-NR (or NR for short), WCDMA, CDMA2000, etc. The processor(s) <NUM> of the base station <NUM> may be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), for base station <NUM> to communicate with a UE device in a manner consistent with embodiments of a hierarchical beamforming structure and communication (transmission) of a beam/QCL indication disclosed herein. Alternatively, the processor(s) <NUM> may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. In the case of certain RATs, for example Wi-Fi, base station <NUM> may be designed as an access point (AP), in which case network port <NUM> may be implemented to provide access to a wide area network and/or local area network (s), e.g. it may include at least one Ethernet port, and radio <NUM> may be designed to communicate according to the Wi-Fi standard. Base station <NUM> may operate according to the various methods and embodiments as disclosed herein for implementing a hierarchical beamforming structure and communication (transmission) of a beam/QCL indication.

<FIG> illustrates an exemplary simplified block diagram illustrative of cellular controller <NUM>, according to some embodiments. It is noted that the block diagram of the cellular communication circuitry of <FIG> is only one example of a possible cellular communication circuit; other circuits, such as circuits including or coupled to sufficient antennas for different RATs to perform uplink activities using separate antennas, or circuits including or coupled to fewer antennas, e.g., that may be shared among multiple RATs, are also possible. According to some embodiments, cellular communication circuitry <NUM> may be included in a communication device, such as communication device <NUM> described above. As noted above, communication device <NUM> may be a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device), a tablet and/or a combination of devices, among other devices.

The cellular communication circuitry <NUM> may couple (e.g., communicatively; directly or indirectly) to one or more antennas, such as antennas 335a-b and <NUM> as shown. In some embodiments, cellular communication circuitry <NUM> may include dedicated receive chains (including and/or coupled to (e.g., communicatively; directly or indirectly) dedicated processors and/or radios) for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for <NUM> NR). For example, as shown in <FIG>, cellular communication circuitry <NUM> may include a first modem <NUM> and a second modem <NUM>. The first modem <NUM> may be configured for communications according to a first RAT, e.g., such as LTE or LTE-A, and the second modem <NUM> may be configured for communications according to a second RAT, e.g., such as <NUM> NR.

As shown, the first modem <NUM> may include one or more processors <NUM> and a memory <NUM> in communication with processors <NUM>.

Similarly, the second modem <NUM> may include one or more processors <NUM> and a memory <NUM> in communication with processors <NUM>.

Thus, when cellular communication circuitry <NUM> receives instructions to transmit according to the first RAT (e.g., as supported via the first modem <NUM>), switch <NUM> may be switched to a first state that allows the first modem <NUM> to transmit signals according to the first RAT (e.g., via a transmit chain that includes transmit circuitry <NUM> and UL front end <NUM>). Similarly, when cellular communication circuitry <NUM> receives instructions to transmit according to the second RAT (e.g., as supported via the second modem <NUM>), switch <NUM> may be switched to a second state that allows the second modem <NUM> to transmit signals according to the second RAT (e.g., via a transmit chain that includes transmit circuitry <NUM> and UL front end <NUM>).

As described herein, the first modem <NUM> and/or the second modem <NUM> may include hardware and software components for implementing any of the various features and techniques described herein. The processors <NUM>, <NUM> may be configured to implement part or all of the features described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively (or in addition), processors <NUM>, <NUM> may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit). Alternatively (or in addition) the processors <NUM>, <NUM>, in conjunction with one or more of the other components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may be configured to implement part or all of the features described herein.

In addition, as described herein, processors <NUM>, <NUM> may include one or more processing elements. Thus, processors <NUM>, <NUM> may include one or more integrated circuits (ICs) that are configured to perform the functions of processors <NUM>, <NUM>. In addition, each integrated circuit may include circuitry (e.g., first circuitry, second circuitry, etc.) configured to perform the functions of processors <NUM>, <NUM>.

In some embodiments, the cellular communication circuitry <NUM> may include only one transmit/receive chain. For example, the cellular communication circuitry <NUM> may not include the modem <NUM>, the RF front end <NUM>, the DL front end <NUM>, and/or the antenna 335b. As another example, the cellular communication circuitry <NUM> may not include the modem <NUM>, the RF front end <NUM>, the DL front end <NUM>, and/or the antenna 335a. In some embodiments, the cellular communication circuitry <NUM> may also not include the switch <NUM>, and the RF front end <NUM> or the RF front end <NUM> may be in communication, e.g., directly, with the UL front end <NUM>.

<FIG> illustrates an exemplary beamforming arrangement. As illustrated in <FIG>, beamforming may be employed to transmit different broadband signals originating from baseband processing units <NUM>, <NUM>, and <NUM> over a number of (in this case three) respective radio frequency (RF) chains <NUM>, <NUM>, and <NUM>, utilizing a number of (in this case <NUM>) antennas <NUM>, with, each RF chain coupling to a respective number of (in this case four) antennas. The beamforming arrangement of <FIG> may represent hybrid beamforming, (i.e., analog/digital beamforming), which is enabled by smaller antenna element size and is thus widely used for certain wireless communications, for example for <NUM>-NR communications. Beam management is important to combat propagation loss for reliable communications, especially for millimeter wave (mmWave) systems.

Different channels/reference symbols may have different requirements associated with beamforming robustness and latency, and they may thus also have different beam/QCL (quasi-co-location) indications. The master information block (MIB) is carried by physical broadcast channel(s) (PBCH) in Synchronization Signal Blocks (SSBs). SSBs with a different block time index in the same burst may be transmitted on different cell specific beams. Beam/QCL indications (also collectively referred to as beamforming information) may be for Group Common PDCCH (GC-PDCCH) and PDCCH. Each UE may be configured with control resource sets for a UE specific search space and for a common search space, e.g. Type <NUM>/Type 0A/Type <NUM>/Type <NUM> common search space, and/or Type <NUM> common search space. The Type <NUM>/Type 0A/Type <NUM>/Type <NUM> common search space has the same beam/QCL as the associated SSB. Specific beams/QCL may be configured through Radio Resource Control (RRC) signaling and/or RRC+MAC-CE signaling for GC-PDCCH in a Type <NUM> common search space carrying SFI (slot format indication), and for PDCCH in a UE specific search space.

The beam/QCL indication for PDSCH may be configured in the Transmission Configuration Indication (TCI) state field in DCI, as illustrated in <FIG>. Through RRC signaling, a UE may be configured with a list of up to a specified number (M) of TCI states <NUM>, and each TCI state may be configured with one reference signal (RS) set. The different TCI states are illustrated in <FIG> as TCI State <NUM> through TCI state M-<NUM>. The QCL reference for PDSCH is dynamically indicated by the TCI field of the DCI. As also shown in <FIG>, each "TCI-RSetConfig" indicates the DL RS in the RS set for the corresponding TCI state, providing the QCL reference. At least the spatial QCL reference may be dynamically updated. The QCL reference for PDCCH may be provided by a semi-statically configured reference to a TCI state. For mmWave, the TCI reference may be the same for all UE-specific search spaces within a control resource set (CORESET), with the CORESETS collectively indicated in <NUM>. The TCI field in DCI may occupy two (<NUM>) or three (<NUM>) bits. There may be support for at least the explicit approach for the update of spatial QCL reference in a TCI state through RRC signaling and/or MAC-CE signaling. The UE may associate one receive (RX) beam with each TCI state during beam synchronization.

Presently, PDSCH (which represents a physical data channel) uses the TCI field in DCI for the beam/QCL indication. This provides fast adaptation to UE position/direction changes, and allows for a quick response from the base station (e.g. from the gNB) to the UE beam quality report. Presently, GC-PDCCH/PDCCH (which represent physical control channels) use RRC signaling and/or RRC+MAC-CE signaling for the beam/QCL indication, which incurs a longer turnaround time, higher traffic overhead, and is also more vulnerable to fast beam-quality changes. The use of an RRC+MAC-CE signaling approach is more suitable for a UE that is in a relatively stable state, and is not a good option for frequent data transmissions in a rapidly changing environment, e.g. when the UE is continually or frequently changing its location. Therefore, it may be advantageous to add a GC-PDCCH/PDCCH beam indication in DCI, for example by adding extra bits in the DCI, especially for higher beam resolution.

Higher beam resolution (a larger number of beam/QCL candidates) may improve link quality between the UE and the base station (e.g. a gNB), but may also be more vulnerable to fast beam-quality changes. Different channels carrying different type of information may be implemented via different beam-resolution based on reliability/audiences. For example, broadcasting channels (channels that are broadcasting) may in general adopt wide beams instead of UE-dedicated narrow beams. It is worth noting that RMSI/OSI/RACH/Page information may have the same beam resolution as SSB. Furthermore, GC-PDCCH beam resolution may be no worse than SSB, and GC-PDCCH may not require higher beam resolution than PDCCH. Additionally, the width of PDCCH beams may be greater than or equal to the width of PDSCH. Therefore, the updating of the RX beam for different channels may not lead to extra and/or duplicated efforts, and different beams/QCL for different channels may be designed/organized in a systematic and scalable fashion.

Pursuant to the above considerations, a beam/QCL indication may be enabled in DCI for a next GC-PDCCH/PDCCH control resource set (CORESET) monitoring for DL grants, in addition to providing the beam/QCL indication for PDSCH for a current GC-PDCCH/PDCCH control resource set. Beam/QCL indication may be included for the next GC-PDCCH/PDCCH monitoring instance and instances thereafter, as illustrated in timeline <NUM> in <FIG>. In some embodiments, the existing DCI formats for DL grants (e.g., formats 1_0 and 1_1) may be modified to include an indication according to a specified number of bits (e.g. an N-bit indication, where N may depend on the beam resolution of the cell). By default, this does not lead to any changes on the PDCCH for DCI formats (e.g., formats 2_0 and 2_1) that do not include a beam indication. Inclusion of a GC-PDCCH/PDCCH beam indication in DCI enables fast response to beam-quality changes between the base station (e.g. gNB) and the UE. In case the GC-PDCCH/PDCCH beam/QCL indication is used because of low PDSCH traffic, it is still possible to use the MAC-CE option.

As seen in <FIG>, in the current agreement timeline <NUM>, a beam/QCL indication in TCI is only configured for PDSCH, which corresponds to a current control resource set, with a beam/QCL indication for PDCCH achieved via MAC-CE signaling. For example, PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM>, and PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM>. A beam/QCL indication for PDCCH <NUM> may be achieved via MAC-CE signaling as shown, with PDCCH <NUM> carrying a beam/QCL indication in TCI configured for PDSCH <NUM>.

In contrast, according to various embodiments, as illustrated in the proposed agreement timeline <NUM>, a beam/QCL indication may be included in TCI not only for the PDSCH for the current PDCCH but also for the next GC-PDCCH/PDCCH monitoring instance and instances thereafter. For example, PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM>, and it may also carry a beam/QCL indication in TCI configured for PDCCH <NUM>. Similarly, PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM>, and it may also carry a beam/QCL indication in TCI configured for PDCCH <NUM>. PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM> as well as a beam/QCL indication in TCI configured for a next PDCCH (not shown).

Various aspects of providing the beam/QCL indication may further be improved through error resilient design considerations. A variety of problems may be encountered during wireless communications, and further improving the provisioning of beam/QCL indications through error resilient design may therefore also further improve wireless communications. For example, in some cases a false CRC pass for PDCCH may cause an unexpected PDCCH beam change. That is, a false pass for a CRC (or false CRC pass) may lead to incorrect GC-PDCCH/PDCCH beam/QC monitoring. For more error resilient design, in some embodiments, the aggregation level for select DCI, e.g. for DCI in which the GC-PDCCH/PDCCH beam indication has changed, may be increased to facilitate the UE's more reliably obtaining the changed beam/QCL indication. In some embodiments, if a current beam/QCL indication is the same as a most recent previous beam/QCL indication, the aggregation level for DCI may be selected/specified to be any desired value. If there is a beam/QCL indication change, the DCI carrying the changed beam/QCL indication may be specified/selected to have a higher aggregation level. In addition, the transmission of select DCI, e.g. DCI in which the GC-PDCCH/PDCCH beam/QCL indication has changed, may be limited to certain (specified) aggregation levels, which may reduce the possibility of a false error-check pass, e.g. a false pass for a CRC (or false CRC pass), thereby reducing the possibility having the wrong beam/QCL GC-PDCCH/PDCCH monitored. For example, in some embodiments, the DCI carrying a changed beam/QCL indication may be limited to one specified aggregation level, and only DCI with that specified aggregation level may carry a changed beam/QCL indication.

In some embodiments, for certain DCI formats that include a GC-PDCCH/PDCCH beam indication, for example, for DCI format 1_0 and 1_1, the base station (e.g. gNB) may change the PDCCH scheduling in a next instance if an ACK or NACK is received for the current DCI that is carrying a changed beam/QCL indication. In case the base station receives a discontinuous transmission (DTX) instead of an ACK or NACK, the base station may transmit both old and new QCL resources, ensuring that regardless of whether or not the UE receives the new PDCCH beam, the UE may receive the PDCCH beam correctly. The same may also apply to MAC-CE based beam change indication(s). This is illustrated in <FIG>, which shows an exemplary timing diagram illustrating the transmission of a beam/QCL indication, implemented with additional features for increased error resiliency, according to some embodiments. As shown in <FIG>, PDCCH <NUM> may carry a beam/QCL indication in TCI configured for PDSCH <NUM>, and it may also carry a beam/QCL indication in TCI configured for PDCCH <NUM>. The beam/QCL indication configured for PDCCH <NUM> may be a changed beam/QCL indication with respect to a previously transmitted beam/QCL indication. Upon receipt of ACK/NACK from the UE for PDSCH <NUM>, the base station transmits PDCCH <NUM> according to the new QCL resources.

In the example shown, the beam/QCL indication carried by PDCCH <NUM> in TCI configured for PDCCH <NUM> may be a changed beam/QCL indication with respect to the beam/QCL indication carried by PDCCH <NUM> in TCI configured for PDCCH <NUM>. Upon receipt of a DTX from the UE for PDSCH <NUM>, the base station transmits both old and new QCL resources to ensure that the UE receives the PDCCH beam correctly. Specifically, the base station (e.g. gNB) transmits PDCCH <NUM> according to the old QCL resources which were carried by PDCCH <NUM> in TCI configured for PDCCH <NUM>, and also according to the new QCL resources which were carried by PDCCH <NUM> in TCI configured for PDCCH <NUM>. Both PDCCH <NUM> and PDCCH <NUM> may also carry beam/QCL indication in TCI configured for PDSCH <NUM>, and PDCCH may also carry beam/QCL indication in TCI configured for PDCCH <NUM>.

According to the invention, the beams are organized into a hierarchical structure. Organizing base station transmit-beams (e.g., gNB transmit-beams, TX beams) for different channels into a hierarchical structure may reduce network traffic overhead for the transmission of beam indication (information), and may also facilitate beam tracking between the base station and the UE for DL communications. The TX beam resolution at the base station side may increase monotonically for channels (i.e., the beam resolution may increase or stay the same for each subsequent channel) in the order shown below:
SSB → GC-PDCCH →PDCCH → PDSCH (high to low order).

That is, the TX beam resolution is higher for the lower order channels than it is for the higher order channels. For example, the TX beam resolution at the base station for PDSCH may be higher than or equal to the beam resolution for PDCCH, which may be higher than or equal to the beam resolution for GC-PDCCH, which may be higher than or equal to the beam resolution for SSB. Beams for channels of a higher order may be wider or equal in width to beams for channels of a lower order, which may reduce the overhead for TX beam sweep. At the UE side, the RX beam for higher order channels may simply be derived from RX beams for lower order channels during a RX beam sweep/update. , the UE may derive the RX beam for PDCCH from the RX beam for PDSCH, and so on. It should be noted that as indicated above, "monotonically increasing" refers to "increasing or remaining the same", in other words, not decreasing. Hence, the TX beam resolution at the base station for PDSCH may be higher than or equal to the beam resolution for PDCCH, and so on and so forth.

In one sense, the RX beam for channels with higher order may be considered as a subset of the RX beam used for lower order channels. By using such a hierarchical structure, the overhead for RX beam tracking/update may be reduced. Thus, according to the invention, the TCI field in DCI is extended to indicate the beams for all four channels, as illustrated in <FIG>. The number of bits used may depend on the number of beams supported for PDSCH in the cell. In other words, the number of bits used in TCI may correspond to the number of beams supported for the PDSCH in the cell. As illustrated in the example shown in <FIG>, up to <NUM> bits may be used if up to <NUM> beams are to be supported at the base station (e.g. at gNB) for PDSCH. The setup of the bit mask for each channel in TCI format may be signaled during RRC connection setup. The example in <FIG> illustrates the two most significant bits providing the beam indication for SSB, the three most significant bits providing the beam indication for GC-PDCCH, the four most significant bits providing the beam indication for PDCCH, and all six bits providing the beam indication for PDSCH.

<FIG> shows an exemplary diagram illustrating a hierarchical beamforming structure with a <NUM>-bit TCI, according to the present invention. The various shaded areas represent the indicated beams for the given resource. As seen in <FIG>, the two most significant bits indicate the respective (possible) beam(s) for SSB. Because of the hierarchical structure, there may be two possible GC-PDCCH beams for (or corresponding to) each possible SSB beam, there may be two possible PDCCH beams for (or corresponding to) each possible GC-PDCCH beam, and finally, there may be two possible PDSCH beams for (or corresponding to) each possible PDCCH beam. Since the bit(s) indicating the beam for a lower order channel are of a lower significance than the bit(s) indicating the beam for a higher order channel, the RX beam for the higher order channel may be derived from the RX beam of the lower order channel. For example, the left beam for PDSCH in <FIG> is indicated by all five bits [<NUM>], from which the four most significant bits indicate the beam for PDCCH, the three most significant bits indicate the beam for GC-PDCCH, and the two most significant bits indicate the beam for SSB.

In some embodiments, channels with a lower order may have the same beam resolution as the channel with a higher order. <FIG> shows an exemplary diagram illustrating a hierarchical beamforming structure with a <NUM>-bit TCI and quasi co-located SSB and GC-PDCCH channels, according to some embodiments. As shown in <FIG>, the SSB and GC-PDCCH channels are quasi co-located, and thus have the same beam resolution. The channel without increased beam resolution may not need any dedicated bit(s) in the TCI format, and the channels with the same beam resolution may therefore be represented by the same bit(s). For example, as shown in <FIG>, both the SSB and GC-PDCCH channels are represented by the two most significant bits. In other words, the two most significant bits indicate both the beam(s) for SSB and the beam(s) for GC-PDCCH.

Furthermore, neighbor beams may also have overlapping child beams. <FIG> shows an exemplary diagram illustrating a hierarchical beamforming structure with a <NUM>-bit TCI, quasi co-located SSB and GC-PDCCH channels, and overlapped beams, according to some embodiments. As shown in <FIG>, two neighbor PDCCH beams may have the same children beams on PDSCH. In the specific example shown in <FIG>, a first PDSCH beam may be identified by [<NUM>] corresponding to the PDCCH beam identified by [<NUM>. ], while also being identified by [<NUM>] corresponding to the PDCCH beam identified by [<NUM>. Similarly, a second PDSCH beam may be identified by [<NUM>] corresponding to the PDCCH beam identified by [<NUM>. ], while also being identified by [<NUM>] corresponding to the PDCCH beam identified by [<NUM>. The same end beam may therefore have different TCI indications, in this case two indications for the same beam. It should be noted that the overlapping beams enable the base station (e.g. a gNB) to change the UE's PDCCH beam without having to change (or adjust/alter) the PDSCH beams, which benefits the UE's mobility, especially when the UE is located at the intersection of two PDCCH beams. The same mobility improvement may also be observed on the SSB/GC-PDCCH level, if those levels also specify overlapping child beams.

Embodiments of the present invention may be realized in any of various forms. For example, in some embodiments, the present invention may be realized as a computer-implemented method, a computer-readable memory medium, or a computer system. In other embodiments, the present invention may be realized using one or more custom-designed hardware devices such as ASICs. In other embodiments, the present invention may be realized using one or more programmable hardware elements such as FPGAs.

Claim 1:
A method for communicating a beam indication, the method comprising:
receiving, by a user equipment device, UE (<NUM>), via wireless communications, downlink control information, DCI, comprising a transmission configuration indication, TCI, state field extended to provide a plurality of beam indications for monitoring a corresponding plurality of different receive channels associated with a hierarchical beamforming structure, wherein a beam resolution increases monotonically from higher order channels to lower order channels, and wherein beams for higher order channels are wider than or equal in width to beams for lower order channels; and
monitoring the plurality of different receive channels using respective corresponding beams obtained by performing beamforming for each respective corresponding beam based at least on a corresponding beam indication of the received plurality of beam indications,
characterized in that
bits of the TCI state field indicating beams used for lower order channels are of lower significance than bits of the TCI state field indicating beams for higher order channels such that beams used for higher order channels are derived from beams used for lower order channels, and bits for indicating beams of a higher order channel are a subset consisting of the most significant bits of the set of bits used for indicating beams of a lower order channel;
wherein the receive channel comprise, from high to low order, an SSB channel, a GC-PDCCH channel, a PDCCH channel, and a PDSCH channel; and
wherein the plurality of beam indications is provided according to a specified number of bits, wherein the specified number depends on a number of beams supported for the PDSCH channel in the cell.