Patent Description:
<NUM>/NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. Some aspects of <NUM>/NR may be based on the <NUM> Long Term Evolution (LTE) standard. There exists a need for further improvements in <NUM>/NR technology.

Wireless communication systems operating under the <NUM>/NR, LTE, and other telecommunication standards use directional antenna beamforming to increase system capacity and to increase link budget. Transmitting and receiving devices may switch beams such as beam directions or beam shapes in some scenarios. However, switching beams may introduce delays and/or transient behavior in the communication channels. There is a need for systems and techniques that allow beam switching in communication devices while also reducing the effect of the beam switching on channel capacity and system throughput.

<CIT> discusses a data symbol transmission method and a wireless network device, which can improve the resource utilization rate and increase the system capacity. <CIT> discusses methods of changing a beamforming configuration during a cyclic prefix that precedes a symbol period. <CIT> discusses a user equipment and a base station that may communicate through one of more beams.

Example techniques disclosed herein include triggering early Tx beam switching before the payload portion of an OFDM symbol ends so as to protect a subsequent symbol from the transient effects of an unsettled beam during a transitioning period.

In accordance with the present invention, there is provided a method of wireless communication as set out in claim <NUM> and a method of wireless communication for early beam switching, wherein early beam switching comprises performing beam switching before a payload portion of an OFDM symbol ends, as set out in claim <NUM>. Other aspects of the invention can be found in the dependent claims.

Several aspects of telecommunication systems are presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements").

As used herein, the term "computer-readable medium" is expressly defined to include any type of computer-readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media. As used herein, the terms "computer-readable medium," "machine-readable medium," "computer-readable memory," and "machine-readable memory" are used interchangeably.

A network that includes both small cell and macro cells may be known as a heterogeneous network. The base stations <NUM> / UEs <NUM> may use spectrum up to Y MHz (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adj acent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The EPC <NUM> may include a Mobility Management Entity (MME <FIG> is a diagram illustrating an example of a wireless communications system and an access network <NUM>.

The base stations <NUM> configured for <NUM> LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC <NUM> through backhaul links <NUM> (e.g., S1 interface). The base stations <NUM> configured for <NUM>/NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network <NUM> through backhaul links <NUM>. The base stations <NUM> may communicate directly or indirectly (e.g., through the EPC <NUM> or core network <NUM>) with each other over backhaul links <NUM> (e.g., X2 interface).

Because of the extremely high path loss and short range of mmW or near-mmW frequencies, the base station <NUM> (e.g., a mmW base station) may use directional beamforming to meet the link budget for communicating with the UE <NUM>. The base station <NUM> may switch the directions or the shapes of the beams when performing beam sweeping or when transmitting different types of signals or payloads. In one aspect, the base station <NUM> may switch beams when performing a beam sweep with the UE <NUM> to establish a combination of Tx beams at the base station <NUM> and Rx beams at the UE <NUM> that meet the link budget, or to refine the Tx beam to better align with the Rx beam to improve the communication link. For example, the base station <NUM> may transmit beamformed reference signals to the UE <NUM> when sweeping through the beams and may receive feedback information from the UE <NUM> on the strength of the reference signals received at the UE <NUM>. The reference signals may be NR-synchronization signals (NR-SS) to determine subframe/symbol timing, channel state information reference signals (CSI-RS) for channel estimation, beam measurement RS (BRS), beam refinement RS (BRRS), sounding reference signals (SRS) for channel quality estimation, etc. In one aspect, the base station <NUM> may switch beams when transmitting control and data channels over different beams. For example, the base station <NUM> may transmit the PDCCH over a first beam and may transmit the physical downlink shared channel (PDSCH) that carries user data, broadcast system information over a second beam. In one aspect, the base station <NUM> may switch beams when transitioning between data and reference signals. For example, the base station <NUM> may transmit the PDSCH using a lower MCS on a wider beam and may transition to transmitting the CSI-RS using a higher MCS on a narrower beam to increase the antenna gain due to the increased susceptibility of the MCS signal of EVM loss.

<FIG> is a diagram <NUM> illustrating antenna beam patterns from various beams of a base station <NUM> and a UE <NUM> in communication with each other. The base station <NUM> and/or the UE <NUM> may have one or more antenna arrays. The antenna arrays may be configured to provide directional beams in a plurality of directions. For example, multiple phased antennas arrays may be used to provide high gain antenna pattern in a direction corresponding to each beam. The base station <NUM> may transmit a beamformed signal to the UE <NUM> in one or more of the beams 402a, 402b, 402c, 402d, 402e, 402f, <NUM>, <NUM>. The UE <NUM> may receive the beamformed signal from the base station <NUM> in one or more receive beams 404a, 404b, 404c, 404d. The UE <NUM> may also transmit a beamformed signal to the base station <NUM> in one or more of the beams 404a-404d. The base station <NUM> may receive the beamformed signal from the UE <NUM> in one or more of the receive beams 402a-<NUM>. The shapes of the beams 402a-<NUM>, 404a-404d may vary in accordance with a desired antenna gain for each beam to meet a link budget. The base station <NUM> / UE <NUM> may perform beamforming sweep and measurements to determine the receive and transmit beams to use for each of the base station <NUM> / UE <NUM> for different types of signals or payloads. The transmit and receive beams for the base station <NUM> may or may not be the same. Similarly, the transmit and receive beams for the UE <NUM> may or may not be the same.

The base station <NUM> / UE <NUM> may change the beam directions and beam shapes of the 402a-<NUM>, 404a-404d by changing the phases of the multiple phased antennas arrays. A transmission path for a signal may include a baseband digital processor configured to modulate data to be transmitted on the subcarriers of an OFDM symbol. The transmission path may include an RF transceiver configured to up-convert, filter, and/or amplify the baseband signal to an RF carrier such as the mmW frequency. The baseband digital processor and the RF transceiver may be configured to change the phases of the multiple phased antennas arrays to transmit the RF signal over the beamformed link. Because of the hardware latencies associated with changing, applying, and/or combining the phases of the multiple phased antennas arrays, there may be a latency from the time the base station <NUM> / UE <NUM> initiates or triggers a beam switch to when the beam settles to the expected value. In one aspect, the latency may include the channel delays, delays through the Rx or Tx filters at the receiver and transmitter, etc. This latency, called the beam switching time, may be a few hundreds of ns in length. During this beam switching time, the beam is in a transient state and data carried by the RF signal over the beam may not be reliability demodulated and decoded.

An OFDM symbol is a cyclic structure that includes a CP followed by a payload carrying the modulated data on the subcarriers. The CP is a cyclic shift of an end portion of the payload and acts as a buffer to guard against ISI from a prior symbol. A receiver receiving the OFDM symbol performs an FFT on the signal samples of the payload to extract the modulated data. Because of the cyclic structure of the OFDM symbol, multipath or channel delays that cause a shift of the signal samples of the CP into the payload do not destroy the orthogonality of the subcarriers modulated with the data, as long as the CP is longer than the channel delays. To mitigate the effect of the unsettled beam over the beam switching time, the base station <NUM> / UE <NUM> may switch beams at the start of the CP of an OFDM symbol. Similar to using the CP to guard against ISI, a receiver performing an FFT on the signal samples of the received payload may demodulate the data on the OFDM subcarriers if the CP is longer than the beam switching time.

Referring again to <FIG>, in certain aspects the base station <NUM>/<NUM> and/or the UE <NUM> may comprise a beam switch component <NUM> configured to initiate beam switching before the end of the full payload portion of an OFDM symbol to reduce the probability of the beam switching time becoming so long that it leaks into the payload of the OFDM and destroys the orthogonality of the subcarriers. For example, the base station <NUM>/<NUM> and/or the UE <NUM> may terminate the payload portion of the OFDM symbol early and may trigger an early beam switch to protect a subsequent symbol from the unduly long transient effects of an unsettled beam. In one aspect, the subsequent symbol to protect may be a "high priority symbol," such as symbols containing DM-RS signals used for channel demodulation and demodulation by a receiver, or CSI-RS used by a receiver to estimate channels for generating the receiver CQI, PMI, or RI measurements. In one aspect, the subsequent symbol may be a data symbol that has high MCS, high coding rate, and/or relatively more stringent reliability requirements. In one aspect, the symbol whose payload is terminated early by the Tx beam switching may be the PDCCH that may have lower MCS, lower coding rate, and/or other symbols that may be relatively more tolerant of EVM loss or decoding errors, and are treated as lower priority symbols.

Although the following description is directed to a base station performing certain of the operations and a UE performing other operations, it should be appreciated that the operations may be performed by either the base station or the UE. Furthermore, while the following description describes the concept using the example of OFDM symbols, it should be appreciated that the techniques disclosed herein may additionally or alternatively apply to discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols and/or single carrier waveform related symbols, such as single carrier-quadrature amplitude modulation (SC-QAM) symbols.

In one aspect, the base station <NUM>/<NUM> may identify one or more potential time instances within the payload of an OFDM symbol to trigger the beam switch and to terminate early the payload. The time may be a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. In one aspect, the base station <NUM>/<NUM> may determine if early termination is needed and the configuration for a beam switch. For example, the base station <NUM>/<NUM> may determine whether to initiate early Tx beam switching based on a predefined method. The predefined method may be known to both the base station <NUM>/<NUM> and the UE <NUM> so that the UE <NUM> may configure its Rx beam to receive the beamformed link after the early beam switching without requiring notification from the base station <NUM>/<NUM>. Based on the predefined method, the UE <NUM> may also configure a time-shifted FFT window for the symbol whose payload is terminated early to capture signal samples of the payload prior to the Tx beam switching and to capture signal samples of a portion of the CP. The UE <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples and to perform the FFT to extract the data modulated on the subcarriers of the OFDM symbol.

In one aspect, the base station <NUM>/<NUM> may determine to initiate early Tx beam switching if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. For example, the base station <NUM>/<NUM> may determine whether to initiate early Tx beam switching based on the beam switching time, the operating environment, and the capability of the UE <NUM> such as the tap delays of its Rx filter, or other parameters of its Rx path that may affect the time for a received switched beam to settle to a quiescent state. The base station <NUM>/<NUM> may receive information on the capability of the UE <NUM> through signaling from the UE <NUM> and may use the information to determine the beam switching time. For example, the base station <NUM>/<NUM> may determine to initiate early Tx beam switching if the beam switching time is longer or close to the length of the CP. In one aspect, the base station <NUM>/<NUM> may determine the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances already identified. The configuration may include a weighted overlapping (Wola) window or other types of window filters that are applied to the early terminated OFDM symbol to control the amount of RF leakage into adjacent bands or channels to satisfy adjacent channel leakage (ACL) regulatory requirements. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

In one aspect, the base station <NUM>/<NUM> may transmit the decision about, and the configuration of, the early Tx beam switching to the UE <NUM> to configure the UE <NUM> to receive the early switched beamformed link. In one aspect, the UE <NUM> may be configured for the early beam switching based on the predefined method so the UE <NUM> does not need notification from the base station <NUM>/<NUM>. The base station <NUM>/<NUM> may terminate the payload of a low priority symbol and may initiate early Tx beam switching at the determined time. In one aspect, the base station <NUM>/<NUM> may apply the Wola window or other types of window filters to the early terminated OFDM symbol and may apply the new phases to the multiple phased antennas arrays to change the beam direction or beam shape.

In one aspect, to receive early switched UL beamformed link from the UE <NUM>, the base station <NUM>/<NUM> may configure its Rx beam to receive the beamformed link. The base station <NUM>/<NUM> may also configure a time-shifted FFT window for the symbol whose payload is terminated early to capture signal samples of the payload prior to the Tx beam switching and signal samples of a portion of the CP. The base station <NUM>/<NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples and to perform the FFT to extract the UL data modulated on the subcarriers of the OFDM symbol.

In one aspect, the UE <NUM> may identify one or more potential time instances within the payload of an OFDM symbol to trigger the beam switch and to terminate early the payload for UL. The time may be a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. In one aspect, the UE <NUM> may determine if early termination is needed and the configuration for a beam switch. For example, the UE <NUM> may determine whether to initiate early Tx beam switching based on a predefined method. The predefined method may be known to both the UE <NUM> and the base station <NUM>/<NUM> so that the UE <NUM> may configure its Rx beam to receive the DL beamformed link after the early beam switching or to configure its Tx beam to initiate the early beam switching for UL without requiring notification from the base station <NUM>/<NUM>. Based on the predefined method, the UE <NUM> may also configure a time-shifted FFT window for the symbol whose payload is terminated early to capture signal samples of the payload prior to the Tx beam switching and signal samples of a portion of the CP. The UE <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples and to perform the FFT to extract the data modulated on the subcarriers of the OFDM symbol. In one aspect, the UE <NUM> may receive the decision about, and the configuration of, early Tx beam switching from the base station <NUM>/<NUM> to configure the UE <NUM> to receive the early switched DL beamformed link or to configure its Tx beam to initiate the early beam switching for UL.

In one aspect, the UE <NUM> may determine to initiate early Tx beam switching if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. In one aspect, the UE <NUM> may determine whether to initiate early Tx beam switching based on the beam switching time, the operating environment, and the capability of the UE <NUM> such as the tap delays of its Tx filter, or other parameters of its Tx path that may affect the beam switching time. For example, the UE <NUM> may determine to initiate early Tx beam switching if the beam switching time is longer or close to the length of the CP. In one aspect, the UE <NUM> may determine the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances already identified. The configuration may include a Wola window or other types of window filters that are applied to the early terminated OFDM symbol to control the amount of RF leakage into adjacent bands or channels to satisfy adjacent channel leakage (ACL) regulatory requirements. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

In one aspect, the UE <NUM> may terminate the payload of a low priority symbol and may initiate early UL Tx beam switching at the determined time. In one aspect, the UE <NUM> may apply the Wola window or other types of window filters to the early terminated OFDM symbol and may apply the new phases to the multiple phased antennas arrays to change the beam direction or beam shape.

Accordingly, for slot configuration <NUM> and numerology µ, there are <NUM> symbols/slot and 2µ slots/subframe. The subcarrier spacing may be equal to 2µ * <NUM>, where µ is the numerology <NUM> to <NUM>. The subcarrier spacing is <NUM> and symbol duration is approximately <NUM>.

At least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM> may be configured to perform aspects in connection with the beam switch component <NUM> of <FIG>.

Wireless communication systems may use the antenna gain of directional beamforming to meet a link budget. For example, a <NUM>/NR device operating in the millimeter wavelength may use beamforming to compensate for the high path loss and short range that may be experienced with such shorter wavelengths. Switching a beam shape or beam direction may help to maintain system robustness and improve throughput. For example, devices may switch beams when performing a beam sweep using reference signals or when transmitting data and/or control channels. In another example, devices may switch beams when transitioning between transmitting loss-tolerant data using a wider beam and transmitting high-reliability reference signals using a narrower beam. Devices may change beam directions or beam shapes by varying the phase shifts of antenna array elements that are combined to generate a beam pattern. However, when a beam is switched, there may be a delay of hundreds of ns from the time a device initiates or triggers a beam switch to when the beam settles to the expected value. During this transition period, sometimes called a "beam switching time," the beam might not be able to be reliably used.

To ameliorate the effects of an unsettled beam during the transition period, transmitter beam switching may occur during the cyclic prefix (CP) portion of an orthogonal frequency division multiplex (OFDM) symbol. A receiver receiving the OFDM symbol may perform a fast frequency transform (FFT) on the payload portion of the OFDM symbol. Thus, transient signals in the CP caused by the beam switching may be ignored. However, when the beam switching time is too long, for example, when caused by channel delays and the transient response of the transmit (Tx) and receive (Rx) filters in the Tx/Rx signal paths, the transient effect of the beam switching may leak into the payload portion of the received OFDM symbol. Such leakage may corrupt the circular structure of the CP-OFDM symbol, similar to the effect of intersymbol interference (ISI) when the channel delay is longer than the CP. The result may be an increase in error vector magnitude (EVM) and decoding errors that may lead to packet loss. The degree of data decoding errors and packet loss may be a function of the type of payload carried by the OFDM symbols. For example, if the OFDM payload is a demodulation reference signal (DM-RS) used by the receiving device for channel estimation and demodulation, EVM loss on the DM-RS symbol may propagate to the demodulation and decoding of subsequent symbols. On the other hand, if the OFDM payload is a data symbol, the EVM loss on the data symbol may be localized and the impact on packet loss may be better contained. In another example, symbols that are transmitted with a low modulation coding scheme (MCS) and, thus, generally more tolerant of EVM loss, may experience less decoding errors than symbols transmitted with higher MCS.

Example techniques disclosed herein include triggering early Tx beam switching before the payload portion of an OFDM symbol ends so as to protect a subsequent symbol from the transient effects of an unsettled beam during the transitioning period. In one aspect, the subsequent symbol to protect may be a "high priority symbol," such as symbols containing DM-RS signals used for channel demodulation and demodulation by a receiver, or channel state information reference signals (CSI-RS) used by a receiver to estimate channels for generating the receiver channel quality indicator (CQI), precoding matrix indicator (PMI), or rank indicator (RI) measurements. In one aspect, the subsequent symbol may be a data symbol that has high MCS, high coding rate, and/or relatively more stringent reliability requirements.

In one aspect, the symbol whose payload is terminated early by the Tx beam switching may be a data symbol such as the physical downlink control channel (PDCCH) that may have lower MCS, lower coding rate, and/or other symbols that may be relatively more tolerant of decoding errors. In one aspect, the receiver receiving the symbol whose payload is terminated early by the Tx beam switching may use a time-shifted FFT window to capture signal samples of the payload prior to the start of the Tx beam switching as well as to capture signal samples of a portion of the CP. The receiver may cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples before performing the FFT. The effect is that the signal samples of the payload that are not captured after the start of the Tx beam switching may be replaced by the captured signal samples from the CP. Due to the cyclic structure of the CP-OFDM symbol, the receiver may extract, demodulate, and decode the payload data modulated on the OFDM sub-carriers. Because the symbol may have lower MCS, even if some of the captured CP signal samples experience an increase in EVM loss due to distortion or transient effects caused by ISI, the receiver may still correctly decode the payload data.

<FIG> is a diagram <NUM> illustrating the timing of Tx beam switching with respect to two OFDM symbols <NUM>, <NUM> at a transmitter with no early termination of a payload and the timing of the FFT window used to capture and extract signal samples at a receiver. A transmitter such as that of the base station <NUM> or the UE <NUM> of <FIG> may transmit two OFDM symbols <NUM>, <NUM>. A first OFDM symbol <NUM> includes a CP <NUM> and a PDCCH payload <NUM>. The PDCCH payload <NUM> may be a low priority payload with low MCS and may be (generally) more tolerant of EVM loss. The CP <NUM> may comprise an end portion of the PDCCH payload <NUM>. In one aspect, the CP <NUM> may comprise a final <NUM> ns portion of the PDCCH payload <NUM>. The first OFDM symbol <NUM> may be transmitted with a wider beam. A second OFDM symbol <NUM> includes a CP <NUM> and a DM-RS payload <NUM>. The CP <NUM> may comprise an end portion of the DM-RS payload <NUM>. The DM-RS payload <NUM> may be a high priority payload with high MCS and (generally) high reliability requirements because the DM-RS signal may be used for channel demodulation and demodulation by a receiver. The second OFDM symbol <NUM> may be transmitted with a narrower beam and a higher antenna gain than the beam of the first OFDM symbol <NUM>.

The transmitter may trigger a beam switch <NUM> at the start of the CP <NUM> of the second OFDM symbol <NUM> to switch from the beam of the first OFDM symbol to the beam of the second OFDM symbol. For example, the transmitter may change the phases of the multiple phased antennas arrays at beam switch trigger <NUM> to change the beam direction and/or the beam shape. Due to hardware latency associated with changing the beam, such as the latency associated with changing the phases of the multiple phased antennas arrays, the beam may not settle until a time instance <NUM> well into the CP <NUM>. In one aspect, a delay <NUM> from the trigger of the beam switch <NUM> to the beam response settled time <NUM> may be <NUM>-<NUM> ns. In addition to the delay <NUM> on the transmitter, the impact of switching the beams may have a delayed impact into the DM-RS payload <NUM> of the second OFDM symbol <NUM>, e.g. due to delay taps of the channel, transmitter / receiver filter, and the receiver front-end, etc., even if the delay <NUM> does not exceed the length of CP <NUM>. During the beam switching time, the beam is in a transient state and the CP <NUM> may not be reliably demodulated and decoded. If the impact of the transient response during the beam switching time extends into the DM-RS payload <NUM>, the cyclic structure of channel matrix associated with the CP <NUM> and the DM-RS payload <NUM> may be corrupted, resulting in EVM loss and decoding errors.

In one aspect, to satisfy adjacent channel leakage (ACL) requirements regulating the amount of channel leakage into the adjacent frequency band of the transmission, the transmitter may apply a first Tx filter <NUM> to the first OFDM symbol <NUM> and a second Tx filter <NUM><NUM> to the second OFDM symbol. The Tx filters <NUM>, <NUM> may be the same or different, and may correspond to a weighted overlapping (Wola) window filter. A receiver may use a first FFT window to capture signal samples of the received PDCCH payload <NUM> of the first OFDM symbol <NUM>. The receiver may use a second FFT window to capture signal samples of the received DM-RS payload <NUM> of the second OFDM symbol <NUM>. The receiver may perform a first FFT on the first FFT window to extract the PDCCH signals modulated on the subcarriers of the first OFDM symbol <NUM>. The receiver may perform a second FFT on the second FFT window to extract the DM-RS signals modulated on the subcarriers of the second OFDM symbol <NUM>. If the negative impact of the beam switching time does not extend into the received DM-RS payload <NUM> and, thus, falls outside of the second FFT window, the receiver may correctly extract, demodulate, and decode the DM-RS signals.

<FIG> is a diagram <NUM> illustrating the timing of early Tx beam switching with respect to two OFDM symbols <NUM>, <NUM> at a transmitter that results in early termination of a payload and the timing of the FFT window used to capture and extract signal samples at a receiver. A transmitter such as that of the base station <NUM> or the UE <NUM> of <FIG> may transmit two OFDM symbols <NUM>, <NUM>. A first OFDM symbol <NUM> includes a CP <NUM> and a PDCCH payload <NUM>. The PDCCH payload <NUM> may be a low priority payload with low MCS and may be (generally) more tolerant of EVM loss, similar to the PDCCH payload <NUM> of <FIG>. The first OFDM symbol <NUM> may be transmitted with a wider beam. A second OFDM symbol <NUM> includes a CP <NUM> and a DM-RS payload <NUM>. The DM-RS payload <NUM> may be a high priority payload, as the DM-RS payload <NUM> of <FIG>. Also as in <FIG>, the second OFDM symbol <NUM> may be transmitted with a narrower beam and a higher antenna gain than the beam of the first OFDM symbol <NUM>.

However, unlike the full PDCCH payload <NUM> of <FIG>, the PDCCH payload <NUM> is terminated early because the transmitter may trigger a beam switch <NUM> prior to the end of the full length PDCCH payload <NUM> of <FIG>, or before the start of the CP <NUM> of the second OFDM symbol <NUM>. Because of the early terminated PDCCH payload <NUM>, the CP <NUM> of the first OFDM symbol <NUM> includes an end portion of the early terminated PDCCH payload <NUM> concatenated with the missing portion of the full length PDCCH payload <NUM> of <FIG> terminated by the early beam switch trigger <NUM>. That is, a portion of the CP <NUM> of the first OFDM symbol <NUM> comprises the missing portion of the full length PDCCH payload <NUM> between the early beam switch trigger <NUM> and the CP <NUM> of the second OFDM symbol <NUM>. The length of the CP <NUM> to guard against intersymbol interference (ISI) is reduced by the length of time between the early beam switch trigger <NUM> and the CP <NUM> of the second OFDM symbol <NUM>, making the first OFDM symbol <NUM> more susceptible to ISI. However, because the PDCCH payload <NUM> is a low priority payload with low MCS that is more tolerant of EVM loss, the receiver is still be able to correctly extract, demodulate, and decode the PDCCH signals even if there is an increase in EVM loss due to distortion or transient effects caused by the early termination. The transmitter may apply a first Tx filter <NUM> to the first OFDM symbol <NUM> to satisfy ACL requirements. Because of the early terminated PDCCH payload <NUM>, the first Tx filter <NUM> starts at the start of the CP <NUM> as the first TX filter <NUM> of <FIG>, but may end earlier compared to the first TX filter <NUM>. The first Tx filter <NUM> may be a Wola window (sometimes referred to as a "Wola filter" or a "Wola window filter").

A receiver receiving the first OFDM symbol <NUM> may use a time-shifted FFT window to capture signal samples of a received PDCCH payload <NUM> prior to the early beam switch trigger <NUM> as well as signal samples of a portion <NUM> of the CP <NUM>. The receiver may cyclically shift the captured signal samples of the portion <NUM> of the CP <NUM> to the end of the captured signal samples of the received PDCCH payload <NUM> before performing the FFT. The effect is that the missing signal samples of the full length PDCCH payload <NUM> after the start of the early beam switch trigger <NUM> are replaced by the captured signal samples from the portion <NUM> of the CP <NUM>. Due to the cyclic structure of the CP-OFDM symbol, the receiver may extract, demodulate, and decode the PDCCH signals modulated on the OFDM sub-carriers.

Due to the early beam switch trigger <NUM>, the beam may settle at a time instance <NUM> within the CP <NUM> of the second OFDM symbol <NUM> that is earlier than the time instance <NUM> of <FIG>, reducing the probability that the beam switching time may extend into the DM-RS payload <NUM> to corrupt the high priority DM-RS payload <NUM>. The transmitter may apply a second Tx filter <NUM> to the second OFDM symbol <NUM> to satisfy ACL requirements. The second Tx filter <NUM> may be a Wola filter. A receiver may use a second FFT window to capture signal samples of a received DM-RS payload <NUM> of the second OFDM symbol <NUM>, as in <FIG>. The receiver may perform a second FFT on the second FFT window to extract the DM-RS signals modulated on the subcarriers of the second OFDM symbol <NUM>.

<FIG> is a diagram illustrating a call flow diagram <NUM> between a base station <NUM> and a UE <NUM> when the base station <NUM> employs early beam switching for downlink communication. The base station <NUM> is the base station <NUM> of <FIG> and the UE <NUM> is the UE <NUM> of <FIG>. At <NUM>, the base station <NUM> identifies one or more potential time instances within the payload of an OFDM symbol to trigger the beam switch and to terminate early the payload. The time is a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. For example, if the beam switching time is long due to the type of narrow beam needed to meet the link budget and the channel delay is long, there is not a strong multipath environment, and the MCS of the high priority symbol is not tolerant of EVM loss, the base station <NUM> may identify an earlier beam switch trigger time within the payload of a low priority OFDM symbol. Moving the beam switch trigger time to an earlier time instance within the payload of the low priority OFDM symbol reduces the probability that the beam switching time extends into the payload of the high priority OFDM symbol. The cost is an increase in the susceptibility of the low priority OFDM symbol to ISI due to the earlier time-shifted FFT window within the CP of the low priority OFDM symbol. In one aspect, the base station <NUM> may identify a group of potential early beam switch trigger times and may select a time from the group at a later time. The base station <NUM> may specify the early beam switch trigger time of a transmission associated with a transmission configuration indicator (TCI) state.

At <NUM>, the base station <NUM> determines if early termination is needed and the configuration for a beam switch. For example, the base station <NUM> determines whether to initiate early Tx beam switching based on a predefined method. The predefined method is known to both the base station <NUM> and the UE <NUM> so that the UE <NUM> may configure its Rx beam to receive the beamformed link after the early beam switching without requiring notification from the base station <NUM>.

In one aspect, the base station <NUM> determines to initiate early Tx beam switching if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. In one aspect, the high priority symbol may contain DM-RS signals used by the UE <NUM> for channel demodulation and demodulation, or CSI-RS used by the UE <NUM> to estimate channels for generating the receiver CQI, PMI, or RI measurements. In one aspect, the high priority symbol may have relatively more stringent reliability requirements. In one aspect, the low priority symbol may contain PDCCH, or other symbols that may be more tolerant of EVM loss or decoding errors. In one aspect, the base station <NUM> may determine whether to initiate early Tx beam switching based on the beam switching time, the operating environment, and/or the capability of the UE <NUM> such as the tap delays of its Rx filter, or other parameters of its Rx path that may affect the beam switching time. In one aspect, the base station <NUM> may receive information on the capability of the UE <NUM> through signaling from the UE <NUM> and may use the information to determine the beam switching time. For example, the base station <NUM> may determine to initiate early Tx beam switching if the beam switching time is longer than or close to the length of the CP. In one aspect, the base station <NUM> may determine the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances identified at <NUM>. The configuration may include a Wola window or other types of window filters that are applied to the early terminated OFDM symbol to control the ACL. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

In one aspect, if the decision for the early Tx beam switching is not based on the predefined method, the base station <NUM> may transmit the decision about, and the configuration of, the early Tx beam switching to the UE <NUM> to configure the UE <NUM> to receive the early switched beamformed link. In one aspect, the base station <NUM> may transmit the decision and configuration information in the DCI of the PDCCH or the ePDCCH, through the RRC layer, or through the MAC layer. In one aspect, the UE <NUM> may be configured for the early beam switching based on the predefined method so the UE <NUM> does not need notification from the base station <NUM>.

At <NUM>, the UE <NUM> configures its Rx beam to receive the early switched beamformed link based on the decision and configuration information of the early Tx beam switching received from the base station <NUM>. In one aspect, the UE <NUM> may configure its Rx beam based on the predefined method. For example, the UE <NUM> configures its Rx beam to receive the CP and the early terminated payload of the low priority OFDM symbol based on the direction and shape of the Tx beam carrying the low priority OFDM symbol from the base station <NUM>. After receiving the low priority OFDM symbol, the UE <NUM> configures its Rx beam to receive the CP and the payload of the high priority OFDM based on the direction and shape of the Tx beam carrying the high priority OFDM symbol.

At <NUM>, the base station <NUM> performs the early Tx beam switching of the low priority OFDM symbol using the switching configuration from <NUM> and transmits the low priority and high priority OFDM symbols to the UE <NUM>. The base station <NUM> terminates the payload of the low priority symbol and initiates early Tx beam switching at the time determined at <NUM>. In one aspect, the base station <NUM> may apply the Wola windows or other types of window filters to the early terminated low priority OFDM symbol and to the high priority OFDM symbols and may apply the new phases to the multiple phased antennas arrays to change the beam direction and/or beam shape. In one aspect, the base station <NUM> may terminate the payload of the low priority symbol, trigger early Tx beam switch, and apply the Wola filters as shown in <FIG>.

At <NUM>, the UE <NUM> may configure the time-shifted FFT window for the low priority symbol whose payload is terminated early to capture the signal samples of the low priority symbol payload prior to the Tx beam switching and the signal samples of a portion of the CP. The UE <NUM> may configure the time-shifted FFT window based on the switching configuration received from the base station <NUM>. In one aspect, the UE <NUM> may configure the time-shifted FFT window based on the predefined method. The UE <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples and to perform the FFT to extract the data modulated on the subcarriers of the low priority OFDM symbol. In one aspect, the signal samples of the low priority symbol payload captured by the FFT window may be the received payload <NUM> of <FIG>, and the signal samples of the portion of the CP of the low priority symbol captured by the FFT window may be the portion <NUM> of the CP <NUM> of <FIG>. Due to the cyclic structure of the CP-OFDM symbol, the UE <NUM> may extract, demodulate, and decode the signals modulated on the sub-carriers of the low priority OFDM symbol. For the high priority symbol, the UE <NUM> may align the FFT window with the payload to capture the signal samples of payload of the high priority symbol. The UE <NUM> may perform the FFT to extract the data modulated on the subcarriers of the high priority OFDM symbol.

<FIG> is a diagram illustrating a call flow diagram <NUM> between a base station <NUM> and a UE <NUM> when the UE <NUM> employs early beam switching for uplink communication. The base station <NUM> is the base station <NUM> of <FIG> or the base station <NUM> of <FIG>, and the UE <NUM> is the UE <NUM> of <FIG> or the UE <NUM> of <FIG>. At <NUM>, if the early Tx beam switching is not based on a predefined method known to both the base station <NUM> and the UE <NUM>, the base station <NUM> identifies one or more potential time instances within the payload of a UL OFDM symbol for the UE <NUM> to trigger the beam switch and to terminate early the payload. The times are a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. In one aspect, the base station <NUM> may receive information on the capability of the UE <NUM> through signaling from the UE <NUM> and may use the information to determine the beam switching time or to identify the potential time instances for the early Tx beam switch. In one aspect, the base station <NUM> may transmit a signal to the UE <NUM> to specify the determined early beam switch trigger time of the UE <NUM>.

At <NUM>, the base station <NUM> determines the configuration for an early UL Rx beam switch at the base station <NUM> to receive the UL beams. In one aspect, the base station <NUM> determines the configuration for an early UL Tx beam switch of the UE <NUM>. In one aspect, the base station <NUM> may receive information on the capability of the UE <NUM> through signaling from the UE <NUM> and may use the information to determine the configuration for the early UL Tx beam switch. The configuration may include a Wola window or other types of window filters that are applied to the early terminated OFDM symbol to control the ACL. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam. The base station <NUM> may transmit the configuration information of the early Tx beam switching to the UE <NUM> to configure the UE <NUM> to transmit the early switched beamformed link. In one aspect, the base station <NUM> may transmit the configuration information or the early beam switch triggers times in the DCI of the PDCCH or the ePDCCH, through the RRC signaling, or through the MAC-CE signaling.

At <NUM>, if the early Tx beam switching is based on a predefined method known to both the base station <NUM> and the UE <NUM>, the UE <NUM> identifies one or more potential time instances within the payload of a UL OFDM symbol for the UE <NUM> to trigger the beam switch and to terminate early the payload without relying on the signaling from the base station <NUM>. The times are a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc..

At <NUM>, the UE <NUM> determines to initiate the early Tx beam switching if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. In one aspect, the high priority symbol has relatively more stringent reliability requirements. In one aspect, the low priority symbol may be more tolerant of EVM loss or decoding errors. In one aspect, the UE <NUM> may determine whether to initiate the early Tx beam switching based on the beam switching time, the operating environment, and the capability of the UE <NUM> such as the tap delays of its Tx filter, or other parameters of its Tx path that may affect the beam switching time. In one aspect, if the UE <NUM> does not receive configuration information from the base station <NUM>, the UE <NUM> determines the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances identified at <NUM>. The configuration may include a Wola window or other types of window filters that are applied to the early terminated OFDM symbol to control the ACL. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

At <NUM>, the UE <NUM> performs the early Tx beam switching of the low priority OFDM symbol using the switching configuration from <NUM> and transmits the low priority and high priority OFDM symbols to the base station <NUM>. The UE <NUM> terminates the payload of the low priority symbol and initiates early Tx beam switching at the time determined at <NUM>. In one aspect, the UE <NUM> may apply the Wola windows or other types of window filters to the early terminated low priority OFDM symbol and to the high priority OFDM symbols and may apply the new phases to the multiple phased antennas arrays to change the beam direction or beam shape. In one aspect, the UE <NUM> may terminate the payload of the low priority symbol, trigger early Tx beam switch, and apply the Wola filters as shown in <FIG>.

At <NUM>, the base station <NUM> configures its Rx beam to receive the early switched UL beamformed link based on the configuration for the early UL Rx beam switch from <NUM>. For example, the base station <NUM> configures its Rx beam to receive the CP and the early terminated payload of the low priority OFDM symbol based on the direction and shape of the Tx beam carrying the low priority OFDM symbol from the UE <NUM>. After receiving the low priority OFDM symbol, the base station <NUM> configures its Rx beam to receive the CP and the payload of the high priority OFDM based on the direction and shape of the Tx beam carrying the high priority OFDM symbol.

At <NUM>, the base station <NUM> may configure the time-shifted FFT window for the low priority symbol whose payload is terminated early to capture the signal samples of the low priority symbol payload prior to the Tx beam switching and the signal samples of a portion of the CP. The base station <NUM> may configure the time-shifted FFT window based on the switching configuration determined at <NUM>. The base station <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples and to perform the FFT to extract the data modulated on the subcarriers of the low priority OFDM symbol. In one aspect, the signal samples of the low priority symbol payload captured by the FFT window may be the received payload <NUM> of <FIG>, and the signal samples of the portion of the CP of the low priority symbol captured by the FFT window may be the portion <NUM> of the CP <NUM> of <FIG>. Due to the cyclic structure of the CP-OFDM symbol, the base station <NUM> may extract, demodulate, and decode the signals modulated on the sub-carriers of the low priority OFDM symbol. For the high priority symbol, the base station <NUM> may align the FFT window with the payload to capture the signal samples of payload of the high priority symbol. The base station <NUM> may perform the FFT to extract the data modulated on the subcarriers of the high priority OFDM symbol.

<FIG> is a flowchart of a method <NUM> of wireless communication for a device to use early Tx beam switching to transmit symbols. In an example, the symbols comprises OFDM symbols. The method <NUM> is performed by a base station (e.g., the base station <NUM> of <FIG>, the base station <NUM> of <FIG>, the base station <NUM> of <FIG>, and/or the apparatus <NUM>/<NUM>' of <FIG>/<FIG>, respectively) or a UE (e.g., the UE <NUM> of <FIG>, the UE <NUM> of <FIG>, the UE <NUM> of <FIG>, and/or the apparatus <NUM>/<NUM>' of <FIG>/<FIG>, respectively). The method may be performed by a processing system <NUM> (of <FIG>), which may include the memory <NUM> and which may be an entire UE <NUM> or base station <NUM> or may be a component of the UE <NUM>, such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>, or a component of the base station <NUM>, such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>. Optional aspects are illustrated with a dashed line. The method enables a device to trigger early Tx beam switching before the payload portion of an symbol ends so as to protect a subsequent symbol from the transient effects of an unsettled beam during a transitioning period.

At <NUM>, the device identifies one or more potential time instances within the payload of an symbol to trigger the beam switch and to terminate early the payload. The identified potential time instance(s) (e.g., the potential early beam switch trigger time(s)) is a function of the type of the low priority symbols whose payload is terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. In one aspect, the device may identify a group of potential early beam switch trigger times and may select a time from the group at a later time. In one aspect, the device identifies an early beam switch trigger time within the payload of a low priority symbol. Moving the beam switch trigger time to a time instance within the payload of the low priority symbol reduces the probability that the beam switching time may extend into the payload of the following high priority symbol. The cost may be an increase in the susceptibility of the low priority symbol to ISI due to the earlier time-shifted FFT window within the CP of the low priority symbol. If the device is a base station communicating with a UE, the device may specify the early beam switch triggers time of a transmission by sending a signaling to a UE.

At <NUM>, the device determines the configuration information and the switching time for the beam switch. In one aspect, the device determines the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances identified at <NUM>. The configuration may include a Wola window or other types of window filters that are applied to the early terminated symbol to control the ACL. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

At <NUM>, the device determines whether to perform switching of the Tx beam early. In one aspect, the device determines to initiate early Tx beam switching when a low priority symbol is followed by a high priority symbol, or when a symbol that has a low MCS is followed by a symbol with a high MCS. In one aspect, the device may determine whether to initiate early Tx beam switching based on the beam switching time, the operating environment, and/or the capability of the receiving device such as the tap delays of its Rx filter, or other parameters of its Rx path that may affect the beam switching time.

If, at <NUM>, the device decides to switch the Tx beam early, then, at <NUM>, the device performs the early Tx beam switching using the switching configuration and the switching time determined at <NUM>. In one aspect, the device terminates the payload of the low priority symbol and may initiate early Tx beam switching before the end of the payload of the low priority symbol at the switching time determined at <NUM>.

At <NUM>, the device may determine one of a transmit filter or a Wola window to be applied to the early Tx beam to, for example, reduce a leakage of a power of the early Tx beam into one or more adjacent frequency channels. In one aspect, the device may apply the Wola windows or other types of window filters to the early terminated low priority symbol and to the high priority symbols and may apply the new phases to the multiple phased antennas arrays to change the beam direction or beam shape.

At <NUM>, the device transmits the switching configuration and a trigger for the switching time to a second device.

If, at <NUM>, the device decides not to switch the Tx beam early, then, at <NUM>, the device performs the Tx beam switching at the end of the payload of the current symbol or the beginning of the CP of the next symbol.

<FIG> is a flowchart of a method <NUM> of wireless communication for a device to receive symbols that are terminated early for early Tx beam switching. The method <NUM> is performed by a base station (e.g., the gNB <NUM> of <FIG>, the base station <NUM> of <FIG>, the base station <NUM> of <FIG>, and/or the apparatus <NUM>/<NUM>' of <FIG>/<FIG>, respectively) or a UE (e.g., the UE <NUM> of <FIG>, the UE <NUM> of <FIG>, the UE <NUM> of <FIG>, and/or the apparatus <NUM>/<NUM>'). In an example, the symbols may comprise OFDM symbols. In an example, the time-shifted window may comprise a time-shifted FFT window. The method may be performed by processing system <NUM>, which may include the memory <NUM> and which may be an entire UE <NUM> or base station <NUM> or may be a component of the UE <NUM> such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM> or a component of the base station <NUM>, such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>. Optional aspects are illustrated with a dashed line. The method enables a device to trigger early Tx beam switching before the payload portion of an symbol ends so as to protect a subsequent symbol from the transient effects of an unsettled beam during a transitioning period.

At <NUM>, the device determines the switching configuration and the switching time of a received beam whose transmission was terminated early within the payload of an symbol. In one aspect, if the device is a base station communicating with a UE, the base station determines the configuration for the early UL Tx beam switch of the UE. For example, the base station may determine the beam direction and the beam shape of the early terminated Tx beam of the UE. The base station may determine the configuration for its Rx beam to receive the CP and the early terminated payload of the UL symbol based on the direction and shape of the early terminated Tx beam of the UE. In one aspect, if the device is a UE communicating with a base station, the UE may receive the configuration of the DL Tx beam switch of the base station. In one aspect, the UE may receive the configuration information in the DCI of the PDCCH or the ePDCCH, through the RRC layer, or through the MAC layer. The UE determines the configuration for its Rx beam to receive the CP and the early terminated payload of the DL symbol based on the configuration of the DL Tx beam switch of the base station. In one aspect, the UE may determine the configuration for its Rx beam for the early beam switching based on the predefined method so the UE does not need to receive the configuration information of the DL Tx beam switch from the base station.

In one aspect, the device determines the switching time of the received beam whose transmission was terminated. In one aspect, if the device is a base station communicating with a UE, the base station determines the switching time of the UL transmission as a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. In one aspect, if the device is a UE communicating with a base station, the UE may receive the switching time of the DL transmission from the base station through a signaling from a second device (e.g., a base station).

At <NUM>, the device transmits the switching configuration and the switching time to a second device.

At <NUM>, the device configures its Rx beam to receive the early switched beamformed link based on the configuration information of the early Tx beam switching. For example, the device configures its Rx beam to receive the CP and the early terminated payload of the low priority symbol based on the direction and shape of the Tx beam carrying the low priority symbol. After receiving the low priority symbol, the device configures its Rx beam to receive the CP and the payload of the high priority based on the direction and shape of the Tx beam carrying the high priority symbol.

At <NUM>, the device configures the time-shifted window for the low priority symbol whose payload is terminated early to capture the signal samples of the low priority symbol payload prior to the Tx beam switching and the signal samples of a portion of the CP. The base station <NUM> configures the time-shifted window based on the switching configuration determined at <NUM>.

At <NUM>, the device may perform a cyclic shift on a portion of the captured signal samples. For example, the base station <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples.

At <NUM>, the device may perform the FFT on the captured and cyclically shifted signal samples of the early terminated symbol in the window to extract the data modulated on the subcarriers of the symbol.

<FIG> is a conceptual data flow diagram <NUM> illustrating the data flow between different means/components in an example apparatus <NUM>. The apparatus <NUM> may correspond to a base station (such as the base station <NUM> of <FIG>, the base station <NUM> of <FIG>, and/or the base station <NUM> of <FIG>) or may correspond to a UE (such as the UE <NUM> of <FIG>, the UE <NUM> of <FIG>, and/or the UE <NUM> of <FIG>). The apparatus <NUM> includes a beam switching time identification component <NUM>, a beam switching configuration determination component <NUM>, a Tx beam switching component <NUM>, an Rx beam configuration component <NUM>, an symbol capturing component <NUM>, and an FFT computation component <NUM>.

The beam switching time identification component <NUM> is configured to identify one or more potential time instances within the payload of a symbol to trigger a beam switch and to terminate early the payload. The one or more identified potential time instances may be a function of the type of the low priority symbols whose payload may be terminated early, the type of the high priority symbols following the low priority symbols, the beam switching time, the link budget, the MCS of the low priority and high priority symbols, the channel conditions, etc. The beam switching time identification component <NUM> may specify the early beam switch trigger time of a transmission using a signaling.

The beam switching configuration determination component <NUM> may be configured to determine if early termination is needed and the configuration for a beam switch. The beam switching configuration determination component <NUM> may be configured to determine to initiate early Tx beam switching if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. In one aspect, if the apparatus <NUM> is a base station (e.g., the base station <NUM>, the base station <NUM>, and/or the base station <NUM>), the high priority symbol may contain DM-RS signals used by the UE (e.g., the UE <NUM>, the UE <NUM>, and/or the UE <NUM>) for channel demodulation and demodulation, or CSI-RS used by the UE to estimate channels for generating the receiver CQI, PMI, or RI measurements. In one aspect, the high priority symbol may have relatively more stringent reliability requirements. In one aspect, the low priority symbol may contain PDCCH, or other symbols that may be more tolerant of EVM loss or decoding errors. In one aspect, the
beam switching configuration determination component <NUM> of the base station may be configured to determine whether to initiate early Tx beam switching based on the beam switching time, the operating environment, and/or the capability of the UE such as the tap delays of its Rx filter, and/or other parameters of its Rx path that may affect the beam switching time. In one aspect, the beam switching configuration determination component <NUM> of the base station may be configured to receive information on the capability of the UE through signaling from the UE and may use the information to determine the beam switching time. For example, the beam switching configuration determination component <NUM> may be configured to determine to initiate early Tx beam switching if the beam switching time is longer than or close to the length of the CP. In one aspect, the beam switching configuration determination component <NUM> may be configured to determine the configuration for the early Tx beam switching including the switching time based on the one or more potential time instances identified at <NUM>. The configuration information may include a Wola window or other types of window filters that are applied to the early terminated symbol to control the ACL. The configuration may include the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam.

The Tx beam switching component <NUM> may be configured to receive the Tx symbols that include a low priority symbol and a high priority symbol and may be configured to perform the early Tx beam switching of the low priority symbol using the switching configuration from the beam switching configuration determination component <NUM>. The Tx beam switching component <NUM> may be configured to transmit the early Tx switched beam that includes the low priority symbols and the high priority symbols to an antenna <NUM> (which may be a base station or a UE). The Tx beam switching component <NUM> may be configured to terminate the payload of the low priority symbol and may initiate early Tx beam switching at the switching time determined by the beam switching configuration determination component <NUM>. In one aspect, the Tx beam switching component <NUM> may apply the Wola windows or other types of window filters to the early terminated low priority symbol and to the high priority symbols and may apply the new phases to the multiple phased antennas arrays to change the beam direction or beam shape. In some examples, the Tx beam switching component <NUM> may transmit the switching configuration and the trigger for the switching time to the antenna <NUM>.

The Rx beam configuration component <NUM> may be configured to receive the early Tx switched beam from the antenna <NUM>. In one aspect, if the apparatus <NUM> is a base station, the Rx beam configuration component <NUM> may be configured to receive the early Tx switched beam based on the configuration information for the beam switching from the beam switching configuration determination component <NUM>. For example, the Rx beam configuration component <NUM> may be configured to change its Rx beam to receive the CP and the early terminated payload of the low priority symbol based on the direction and shape of the Tx beam carrying the low priority symbol. After receiving the low priority symbol, the Rx beam configuration component <NUM> may be configured to change its Rx beam to receive the CP and the payload of the high priority symbol based on the direction and shape of the Tx beam carrying the high priority symbol.

The symbol capturing component <NUM> may be configured to time-shift the window for the low priority symbol whose payload is terminated early to capture the signal samples of the low priority symbol payload prior to the Tx beam switching and the signal samples of a portion of the CP. The symbol capturing component <NUM> may configure the time-shifted window based on the beam switching time or the beam switching configuration information from the beam switching configuration determination component <NUM>. The symbol capturing component <NUM> may be configured to cyclically shift the captured signal samples of the CP portion to the end of the captured payload signal samples.

The FFT computation component <NUM> may perform the FFT on the captured and cyclically shifted signal samples of the early terminated symbol in the window to extract the data modulated on the subcarriers of the symbol.

The apparatus <NUM> may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of <FIG> and/or <NUM>. As such, each block in the aforementioned flowcharts of <FIG> and/or <NUM> may be performed by a component and the apparatus <NUM> may include one or more of those components.

<FIG> is a diagram <NUM> illustrating an example of a hardware implementation for an apparatus <NUM>' employing a processing system <NUM>. The processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> links together various circuits including one or more processors and/or hardware components, represented by a processor <NUM>, the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and computer-readable medium / memory <NUM>. The bus <NUM> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system <NUM> may be coupled to a transceiver <NUM>. The transceiver <NUM> is coupled to one or more antennas <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <NUM> receives a signal from the one or more antennas <NUM>, extracts information from the received signal, and provides the extracted information to the processing system <NUM>, specifically the symbol capturing component <NUM>. In addition, the transceiver <NUM> receives information from the processing system <NUM>, specifically the Tx beam switching component <NUM>, and based on the received information, generates a signal to be applied to the one or more antennas <NUM>. The processing system <NUM> includes the processor <NUM> coupled to the computer-readable medium / memory <NUM>. The processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory <NUM>. The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described supra for any particular apparatus. The computer-readable medium / memory <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software. The processing system <NUM> further includes at least one of the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The components may be software components running in the processor <NUM>, resident/stored in the computer readable medium / memory <NUM>, one or more hardware components coupled to the processor <NUM>, or some combination thereof. The processing system <NUM> may be a component of the base station <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>. The processing system <NUM> may be a component of the UE <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>.

In one configuration, the apparatus <NUM>' for wireless communication includes means for identifying one or more potential time instances within the payload of a symbol to trigger a beam switch and to terminate early the payload. The apparatus <NUM>' includes means for determining if early termination is needed and a configuration for the beam switch. Early termination may be initiated if a low priority symbol is followed by a high priority symbol, or a symbol that has a low MCS is followed by a symbol with a high MCS. The configuration may include the switching time, a Wola window or other types of window filters that are applied to the early terminated symbol to control the ACL, the new phases of the multiple phased antennas arrays to change the direction and/or the shape of the early switched beam, etc..

The apparatus <NUM>' includes means for receiving the Tx symbols that include a low priority symbol and a high priority symbol for performing the early Tx beam switching of the low priority symbol using the switching configuration. The apparatus <NUM>' includes means for receiving the early Tx switched beam from the antenna <NUM>. In one aspect, if the apparatus <NUM>' is a base station, the apparatus <NUM>' includes means for receiving the early Tx switched beam based on the configuration information. The apparatus <NUM>' includes means for time shifting the window for the low priority symbol whose payload is terminated early to capture the signal samples of the low priority symbol payload prior to the Tx beam switching and the signal samples of a portion of the CP. The means for time shifting the window may include means for configuring the time-shifted window based on the beam switching time or the beam switching configuration information. The means for time shifting the window may include means for cyclically shifting the captured signal samples of the CP portion to the end of the captured payload signal samples. The apparatus <NUM>' includes means for performing the FFT on the captured and cyclically shifted signal samples of the early terminated symbol in the window to extract the data modulated on the subcarriers of the symbol.

The aforementioned means may be one or more of the aforementioned components of the apparatus <NUM>' and/or the processing system <NUM> of the apparatus <NUM>' configured to perform the functions recited by the aforementioned means. As described supra, the processing system <NUM> may be a component of the base station <NUM> and may include memory <NUM> and or at least one of the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM>. Alternatively, the processing system <NUM> may be the entire base station (e.g., see the base station <NUM> of <FIG>). As described supra, the processing system <NUM> may be a component of the UE <NUM> and may include memory <NUM> and or at least one of the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM>. Alternatively, the processing system <NUM> may be the entire UE (e.g., see the UE <NUM> of <FIG>).

Claim 1:
A method of wireless communication, comprising:
identifying (<NUM>), by a device, a potential time for early beam switching within a transmission interval of a first symbol, wherein the first symbol is an orthogonal frequency division multiplexing, OFDM, symbol and early beam switching comprises initiating beam switching before the end of the full payload portion of the first symbol;
determining (<NUM>), by the device, whether to switch a transmit, Tx, beam early based on if the first symbol is a low priority symbol and a second symbol is a high priority symbol, the second symbol following the potential time for the early beam switching;
determining (<NUM>) a switching configuration and a switching time based on the potential time for the early beam switching; and
initiating switching (<NUM>), by the device, before the end of the full payload portion of the first symbol, the Tx beam early using the switching configuration and the switching time in response to determining to switch the Tx beam early.