Patent Description:
Aspects of the present disclosure generally relate to wireless communications, and more particularly to techniques and apparatuses for <NUM> new radio (NR) tracking reference signals for idle mode user equipment (UE) power saving.

Wireless communications systems are widely deployed to provide various telecommunications services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and/or the like). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE/LTE-Advanced is a set of enhancements to the universal mobile telecommunications system (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

A wireless communications network may include a number of base stations (BSs) that can support communications for a number of user equipment (UEs). The downlink (or forward link) refers to the communications link from the BS to the UE, and the uplink (or reverse link) refers to the communications link from the UE to the BS.

The above multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level.

Power saving is important for UEs. A UE can enter an inactive or idle mode to conserve battery power. During idle (for LTE/NR UEs)/inactive (for NR UEs) mode operation, the UE periodically monitors a paging channel to receive paging messages from the base station. The UE may also be configured to monitor reference signals, such as a tracking reference signal (TRS), when the UE is in the inactive mode or the idle mode. It would be desirable to configure the TRS to allow idle/inactive mode UEs to save power.

US patent application with publication number <CIT> discloses that a base station may determine that a triggering event associated with a user equipment (UE) has occurred. The UE may receive, based at least in part on an occurrence of a triggering event associated with the UE, a trigger signal that identifies resources to be used for transmission of an aperiodic tracking reference signal (TRS). The UE may receive the aperiodic TRS based at least in part on the trigger signal and the identified resources. The UE may perform at least one of a tracking function, or a synchronization function, or an alignment function, or a combination thereof, in response to the occurrence of the triggering event and based at least in part on the aperiodic TRS.

PCT application with publication number <CIT> discloses an apparatus for a base station transceiver of a mobile communication system including at least one interface for communicating with a transceiver module of the base station transceiver. The apparatus includes a control module configured to provide a reference signal to a user equipment of the mobile communication system via the transceiver module. The reference signal is a reference signal for time tracking. Control module is configured to provide a downlink control signal to the user equipment via the transceiver module. The reference signal and the downlink control signal are quasi-co-located.

PCT application with publication number <CIT> discloses a method for timing and frequency tracking and paging detection. The method includes performing a timing and frequency tracking based on a timing/frequency tracking reference signal (RS) at a user equipment (UE) in a beam formed wireless communication system, and performing a paging detection at a first paging occasion (PO) that is quasi-co-located (QCLed) with the first timing/frequency tracking RS. The first timing/frequency tracking RS is one of a sequence of timing/frequency tracking RSs transmitted on beams of a beam sweeping, and is associated with a beam index. The first PO is within a PO window that includes a sequence of POs transmitted on beams of a beam weeping, and is associated with the same beam index as the first timing/frequency tracking RS.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and processing system as substantially described with reference to and as illustrated by the accompanying drawings and specification.

So that features of the present disclosure can be understood in detail, a particular description may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

Various aspects of the disclosure are described more fully below with reference to the accompanying drawings. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth. It should be understood that any aspect of the disclosure disclosed may be embodied by one or more elements of a claim.

Several aspects of telecommunications systems will now be presented with reference to various apparatuses and techniques.

It should be noted that while aspects may be described using terminology commonly associated with <NUM> and later wireless technologies, aspects of the present disclosure can be applied in other generation-based communications systems, such as and including <NUM> and/or <NUM> technologies.

Power saving is important for UEs. A UE can enter an inactive or idle mode to conserve battery power. During idle (for LTE or NR UEs) or inactive (for NR UEs) mode operation, the UE periodically monitors a paging channel to receive paging messages from the base station. When not monitoring, the UE is able to sleep and save power. If the UE does not detect a paging message indicating the presence of data or a call, the UE may go back to sleep until the next paging occasion.

The UE may also be configured to monitor reference signals, such as a tracking reference signal (TRS), when the UE is in the inactive mode or the idle mode. According to aspects of the present disclosure, configuring of the TRS can allow idle/inactive mode UEs to save power. Additional aspects of the present disclosure are directed to usage of a configured tracking reference signal (TRS) for purposes other than tracking.

The network <NUM> may be a <NUM> or NR network or some other wireless network, such as an LTE network. Each BS may provide communications coverage for a particular geographic area.

A BS may provide communications coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. The terms "eNB," "base station," "NR BS," "gNB," "TRP," "AP", "node B," "<NUM> NB," and "cell" may be used interchangeably herein.

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

The wireless network <NUM> may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network <NUM>.

The network controller <NUM> may communicate with the BSs via a backhaul.

UEs <NUM> (e.g., 120a, 120b, 120c) may be dispersed throughout the wireless network <NUM>, and each UE may be stationary or mobile. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communications device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communications (MTC) or evolved or enhanced machine-type communications (eMTC) UEs. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communications link. Some UEs may be considered a customer premises equipment (CPE).

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

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. The transmit processor <NUM> may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. The transmit processor <NUM> may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS)) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). Each modulator <NUM> may process a respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM) and/or the like) to obtain an output sample stream.

At the UE <NUM>, antennas 252a through 252r may receive the downlink signals from the base station <NUM> and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. A receive processor <NUM> may process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE <NUM> to a data sink <NUM>, and provide decoded control information and system information to a controller/processor <NUM>. In some aspects, one or more components of the UE <NUM> may be included in a housing.

On the uplink, at the UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (e.g., for discrete Fourier transform spread OFDM (DFT-s-OFDM), cyclic prefix (CP)-OFDM, and/or the like), and transmitted to the base station <NUM>. At the base station <NUM>, the uplink signals from the UE <NUM> and other UEs may be received by the antennas <NUM>, processed by the demodulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE <NUM>. The receive processor <NUM> may provide the decoded data to a data sink <NUM> and the decoded control information to a controller/processor <NUM>. The base station <NUM> may include communications unit <NUM> and communicate to the network controller <NUM> via the communications unit <NUM>. The network controller <NUM> may include a communications unit <NUM>, a controller/processor <NUM>, and a memory <NUM>.

The controller/processor <NUM> of the base station <NUM>, the controller/processor <NUM> of the UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with tracking reference signals for power savings with idle/inactive mode UEs, as described in more detail elsewhere. For example, the controller/processor <NUM> of the base station <NUM>, the controller/processor <NUM> of the UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, the process of <FIG> and/or other processes as described. Memories <NUM> and <NUM> may store data and program codes for the base station <NUM> and UE <NUM>, respectively.

In some aspects, the base station <NUM> may include means for configuring, means for partitioning, means for scheduling, means for aligning and means for transmitting. The UE <NUM> may include means for expecting, means for monitoring, and means for communicating. Such means may include one or more components of the base station <NUM> and UE <NUM> described in connection with <FIG>.

Power saving is important for UEs. A UE may enter an inactive mode or idle mode to conserve battery power. During idle (for LTE or NR UEs) or inactive (for NR UEs) mode operation, the UE periodically monitors a paging channel during a paging occasion to receive paging messages from the base station. When not monitoring, the UE is able to sleep, saving power. If the UE does not detect a paging message indicating the presence of data or a call, the UE may go back to sleep until the next paging occasion. During the paging occasion, the UE decodes a physical downlink control channel (PDCCH) to obtain paging downlink control information (P-DCI). If the P-DCI so indicates, the UE will then decode the physical downlink shared channel (PDSCH) to obtain the paging message.

The UE may also be configured to monitor reference signals, such as a tracking reference signal (TRS), when the UE is in the inactive mode or the idle mode. A tracking reference signal includes four OFDM symbols in two consecutive slots. A base station may configure the UE with occasions for reference signals, during which the base station transmits the reference signals. According to the present disclosure, configuring of the TRS may allow idle/inactive mode UEs to save power.

An objective for power saving in idle/inactive mode includes specifying enhancements for idle/inactive mode UE power saving, considering system performance. Paging enhancements are desired to reduce unnecessary UE paging receptions, without impacting legacy UEs. Another objective is to specify potential tracking reference signal (TRS)/channel state information reference signal (CSI-RS) occasions available in connected mode to idle/inactive mode UEs, while reducing system overhead impact.

For a UE modem implementation that uses synchronization signal block (SSB) sets as input to a tracking loop (e.g., a frequency tracking loop (FTL) or time tracking time loop (TTL)), reception of one or more SSB sets may be needed, especially under poor channel conditions. The UE may be able to enter "light sleep" in between SSBs and/or paging occasions (POs), but overall this reduces deep sleep time and incurs multiple wake-up/go-to-sleep overhead. Moreover, the transition from light sleep to deep sleep consumes energy.

In LTE, a cell reference signal (CRS) is transmitted relatively often, which allows sample capture and enables offline processing of the signal. In <NUM> NR, there is no CRS, only SSBs as the reference signal (with typically a <NUM> msec periodicity). There is no offline mode due to the potential large gap between the SSB and the page.

<FIG> is a diagram illustrating beam selection, in accordance with aspects of the present disclosure. As seen in <FIG>, for FR1 (frequency range one - sub <NUM>), a page may be beamformed, where up to eight beamformed SSBs may be transmitted and up to eight beamformed copies of the page (with a one-to-one correspondence to the SSBs) will be transmitted. In <FIG>, each pattern represents a different beam direction. Thus, the SSB set includes the set of SSBs for all directions. The UE selects the best beam based on the SSBs and decodes the corresponding page.

It is desirable to make a tracking reference signal/channel state information reference signal (TRS/CSI-RS) available to idle/inactive mode UEs to help with tracking loops. Because the UE is not in a connected state, alternative methods enable signaling TRS/CSI-RS information to idle/inactive UEs. A first method utilizes a short message (e.g., a physical downlink control channel (PDCCH) with cyclic redundancy check (CRC) scrambled by a paging radio network temporary identifier (P-RNTI)). Reserved bits in DCI format 1_0 for the short message may be used. A second method utilizes a paging message (e.g., a physical downlink shared channel (PDSCH) scheduled by a PDCCH with CRC scrambled by a P-RNTI). A third method utilizes new paging downlink control information (DCI) signaling (e.g., a separate resource from legacy paging DCI) with a TRS/CSI-RS occasion configuration and the identifier for the paging/UE group.

Aspects of the present disclosure are directed to configuration options and conditions, along with tradeoffs with UE power saving. Additional aspects of the present disclosure are directed to usage of configured TRS/CSI-RS other than for tracking.

<FIG> are diagrams illustrating tracking reference signal (TRS) configurations, in accordance with aspects of the present disclosure. Aspects of the present disclosure are directed to configuration options for UE power saving. In one aspect, a TRS <NUM> is not aligned to a paging occasion (PO) <NUM>, as seen in <FIG>. That is, the TRS <NUM> arrives at least one slot before the paging-downlink control information (P-DCI) of the paging occasion <NUM>. During the paging occasion <NUM>, the UE decodes a physical downlink control channel (PDCCH) to obtain paging downlink control information (P-DCI). If the P-DCI so indicates, the UE will then decode a physical downlink shared channel (PDSCH) <NUM> to obtain the paging message. This time division multiplexed (TDM) TRS <NUM> is beneficial for UE power saving when the configuration reduces the number of SSBs needed for reception within a paging cycle, for example, when channel conditions are poor. That is, the TRS <NUM> can supplement or replace SSBs for tracking. Thus, SSBs may be sent less frequently.

As seen in <FIG>, the TRS <NUM> may be aligned to the PO <NUM>. The UE may save power by reducing the number of wake-ups within a paging cycle. That is, the UE can awaken once for both the TRS <NUM> and the P-DCI of the PO <NUM>. If the P-DCI so indicates, the UE will then decode the physical downlink shared channel (PDSCH) <NUM> to obtain the paging message. The UE may also perform offline processing. For example, the UE may capture samples and run the FTL/TTL on the TRS <NUM>, for page detection. It is noted that it is easier for the base station to align the TRS <NUM> (which can be UE/group-specific) to the PO <NUM>, compared to aligning the SSB to the PO <NUM>. It is also noted that this configuration seen in <FIG> can support unaligned TRS/PO. That is, frequency division multiplexing (FDM) may still occur. Although full frequency division multiplexing is shown in <FIG>, the present disclosure also contemplates partial frequency division multiplexing.

<FIG> illustrates an enhanced paging DCI design/configuration that is similar to the configuration shown in <FIG>. In the configuration of <FIG>, however, a group of UEs on the same PO <NUM> that would monitor paging DCI with the same P-RNTI is partitioned. In other words, UEs belonging to the same PO <NUM> may be partitioned into multiple groups (e.g., associated with different P-RNTIs). Because of the partitioning, in the configuration shown in <FIG>, there is a reduced likelihood of PDSCH decoding. Thus, a PDSCH <NUM> in <FIG> is represented differently from the PDSCH <NUM> shown in <FIG>. According to further aspects, a different TRS <NUM> may be associated with different groups.

<FIG> illustrates an enhanced paging DCI design/configuration. In the configuration of <FIG>, a non-zero minimum offset (k0) for paging is supported. That is, the offset k0 ≥ <NUM> implements cross-slot scheduling for idle/inactive mode UEs. Cross-slot scheduling specifies the PDCCH including the P-DCI is scheduled one or more slots before the corresponding PDSCH <NUM>. Cross-slot scheduling may save power because the UE only warms up enough hardware to decode the paging DCI (and processes the TRS for loop tracking, if needed) at the PO <NUM>. Only if the DCI is successfully decoded, the UE warms up the hardware for PDSCH processing. Assuming the DCI decode rate is low, cross-slot scheduling prevents the UE from unnecessarily expending energy to prepare for PDSCH reception/decoding. The assumption is reasonable because the paging rate is typically very low. Although <FIG> shows cross-slot scheduling in conjunction with partitioned UEs (seen by the representation of the PDSCH <NUM>), cross-slot scheduling may operate without partitioning the UEs. In <FIG>, the TRS <NUM> aligns with the PO <NUM>.

<FIG> illustrates a TRS configuration including a PDCCH-based wake-up signal (WUS) <NUM> as part of the claimed invention. The wake-up signal <NUM>, instead of the paging DCI (P-DCI), indicates in advance of a PO <NUM> whether the UE should wake up to decode the paging DCI and PDSCH <NUM>. The wake-up signal (WUS) <NUM> is aligned with the TRS <NUM>. In the example of <FIG>, the paging occasion is partitioned and is represented differently than the paging occasion <NUM> of <FIG>.

<FIG> illustrates another TRS configuration in which a TRS-based wake-up signal is present. A TRS <NUM> is used as a wake-up signal in some options, where the existence of the TRS <NUM> may be used to infer whether the UE should decode the P-DCI at the PO <NUM> and also the PDSCH <NUM>. One issue with this option is that if the UE is not indicated to wake-up for a long time, a TRS <NUM> is not present for a long time and the UE time/frequency tracking loops may not be able to base their references on a TRS <NUM>. In another option, two different scrambling sequences are provided, one indicating wake-up, and the other indicating do not wake up. This option is better for the UE when the UE specifies the TRS <NUM> is always to be present, to maintain time/frequency tracking. The UE performs hypothesis testing. For example, if none of the UEs on the PO <NUM> are paged, the WUS is not transmitted and the UE can skip decoding of paging.

According to the claimed invention, a TRS is transmitted only when there is a transmission on the PDSCH (<NUM>). That is, the base station decides to transmit the TRS conditioned on there being a transmission on the PDSCH (<NUM>). This conditional sending of TRS occurs when the TRS is primarily used for PDSCH decoding. From the UE perspective, the UE expects the TRS to be transmitted when the PDSCH is transmitted.

<FIG> are diagrams illustrating tracking reference signal (TRS) configurations for paging physical downlink shared channel (PDSCH) decoding, in accordance with aspects of the present disclosure. A TRS <NUM> may overlap with a PDSCH <NUM> in time, as seen, for example, in <FIG>. Overlap in time in this context means at least part of the TRS <NUM> and PDSCH <NUM> transmission are in a same slot. Time/frequency error requirements for decoding PDCCH are low and should be sufficient enough to drive tracking loops based on SSB alone. The TRS <NUM> is used only for loop refinement for PDSCH decoding. According to other aspects of the present disclosure, a transmitted PDCCH-demodulation reference signal (DM-RS) may also be used for loop refinement. The UE may use the PDCCH DM-RS in addition to the SSB set. Loop refinement refers to reducing time and frequency error for the UE relative to the base station.

The TRS <NUM> is intended to help with PDSCH decoding for two use cases including paging PDSCH <NUM> and other system information (OSI)/system information block (SIB) PDSCH <NUM>. For the paging PDSCH <NUM>, the TRS <NUM> aligns to the PDSCH <NUM> to reduce the number of wake-ups. In <FIG>, cross-slot scheduling is employed where the PO <NUM> for the paging DCI is in a slot before the PDSCH <NUM>. In the invention, the TRS <NUM> is transmitted only when there is transmission on the PDSCH (<NUM>). In <FIG>, conventional scheduling occurs where the paging DCI in the PO <NUM> is in the same slot as the PDSCH <NUM>. In this case, the TRS <NUM> is also transmitted when there is transmission on the PDSCH (<NUM>) is transmitted. In <FIG>, the TRS <NUM> is represented differently than the TRS <NUM> in <FIG> due to the fact that the TRS <NUM> of <FIG> is conditional. That is, there is a reduced likelihood of the TRS <NUM> appearing. Although the occasional PDSCH <NUM> is shown, the standard PDSCH <NUM> is also contemplated.

A PDSCH may carry other system information (OSI)/system information block (SIB) within a paging cycle. The OSI/SIB PDSCH may be transmitted on multiple beams, for example, as discussed with reference to <FIG> for PDCCH. The portions of the PDSCH relevant to a particular UE may not be close to the beams of interest for the SSBs. Thus, the UE may have to wake up an extra time or remain active longer to receive the SSBs for decoding the OSI/SIB PDSCH, leading to higher power consumption. To address this issue, aspects of the present disclosure include TRSs configured to align with the OSI/SIB PDSCH (see, for example, <FIG>). The TRSs can drive the frequency tracking loops (FTLs) and time tracking loops (TTLs), replacing the use of SSBs for loop tracking. Moreover, it is easier for a network to configure TRS with better alignment to the OSI/SIB PDSCH.

If paging DCI is always in the same slot as its associated PDSCH, there is no ambiguity about paging occasion (PO) alignment. Aspects of the present disclosure address situations when the paging DCI is not always in the same slot as the associated PDSCH. For example, with the k0 > <NUM> proposal (discussed with respect to <FIG>), paging DCI may be transmitted in a different slot than the associated PDSCH. There are several ways to define the relative alignment to PO when k0 > <NUM>.

<FIG> is a diagram illustrating paging occasion (PO) alignment, in accordance with aspects of the present disclosure. In <FIG>, UEs may be split into two groups, for example based on P-RNTI. For one of the groups, the PDSCH <NUM> arrives two slots after the DCI (e.g., k0=<NUM> as seen in <FIG>). In this case, the paging occasion (PO) <NUM> aligns with the DCI arriving two slots before the PDSCH <NUM>. The PDSCH slot is associated with UEs from both groups in <FIG> and the TRS <NUM> overlaps with the PDSCH <NUM>. An issue with this solution may occur with a legacy UE not built to support k0 > <NUM>. In this case, for the same PO <NUM>, multiple possible slot locations exist for the PDSCH <NUM> (and associated TRS <NUM> if overlap is desired).

<FIG> is a diagram illustrating paging occasion (PO) alignment, in accordance with other aspects of the present disclosure. <FIG> shows an alternate configuration for the paging occasion (PO) <NUM>. In this configuration, the PO <NUM> aligns to the expected slot where PDSCH <NUM> could be transmitted. In this configuration, dynamically indicating k0 out of a range of possible values in the paging DCI does not help the UE to decide which slot to monitor for the DCI, relative to the PO <NUM>. A fixed offset for k0 is indicated to the UE (for example, derived from the UE ID, and/or the P-RNTI used by the UE). Because PDSCH transmission should not happen frequently, it may be possible that several k0 offsets are supported from the same PDSCH slot. In the example shown in <FIG>, different groups of UEs are associated with different k0 offsets, which is another way to implement UE partitioning/grouping (working in conjunction with or without grouping by different P-RNTI).

<FIG> illustrates a special case where a first group of UEs is assigned k0=<NUM> and a second group of UEs is assigned k0=<NUM>. Because legacy UEs built to support older versions of the standard do not support the k0 > <NUM> offset, the legacy UEs use the value k0=<NUM>. Hence, legacy UEs assume k0=<NUM>. In these aspects of the present disclosure, all UEs monitor for paging DCI at the PO <NUM> aligned with the slot where the PDSCH <NUM> could be transmitted. The TRS <NUM> overlaps the PDSCH <NUM>.

<FIG> is a flow diagram illustrating the process <NUM> performed by a base station, in accordance with the claimed invention. The process <NUM> includes configuring and transmitting a tracking reference signal (TRS) for idle/inactive mode user equipment (UE).

As shown in <FIG>, the process <NUM> includes configuring a tracking reference signal (TRS) with respect to a PDSCH (physical downlink shared channel) for an idle/inactive mode UE (user equipment) (block <NUM>). In the claimed invention, the base station (e.g., using the controller/processor <NUM>, memory <NUM>, and or the like) configures the tracking reference signal (TRS) with respect to the PDSCH. The TRS is aligned with the paging occasion or aligned with a PDSCH associated with the paging occasion. In some examples, the TRS is frequency division multiplexed or time division multiplexed with the PDSCH.

As shown in <FIG>, process <NUM> includes transmitting the tracking reference signal during a paging cycle corresponding to the paging occasion, in accordance with the configuration (block <NUM>). The base station (e.g., using the antenna <NUM>, MOD <NUM>, TX MIMO processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and or the like) can transmit the tracking reference signal and the PDSCH. In some examples, the base station partitions a group of UEs into different groups, and transmits a different TRS to each group. In other examples, the TRS functions a wake up signal to instruct a UE to later monitor for the paging occasion. In still other examples, the TRS is only transmitted when a PDSCH is transmitted.

Claim 1:
A method (<NUM>) of wireless communication by a base station, comprising:
configuring (<NUM>) time and/or frequency resources for a pattern of a tracking reference signal, TRS, with respect to a paging occasion for an idle mode user equipment, UE, or an inactive mode UE, the pattern of the TRS including a first set of signals in a first slot that occurs before a second slot, the first slot including the first set of signals of the TRS, and the second slot including a wake-up signal and a second set of the TRS, the second set of signals aligned with the wake-up signal of signals in the second slot; and
transmitting (<NUM>) the TRS during a paging cycle corresponding to the paging occasion, in accordance with the configuring, the transmitting of the TRS occurring in response to transmission on a physical downlink shared channel, PDSCH, and the transmitting not occurring when there is no transmission on the PDSCH.