Patent Description:
Fifth generation (<NUM>) wireless communications networks are a next generation of mobile communications networks. Standards for <NUM> communications networks are currently being developed by the Third Generation Partnership Project (3GPP). These standards are known as 3GPP New Radio (NR) standards.

<NPL>, discloses a physical downlink control channel (PDCCH) being associated with a power saving downlink control information (PS-DCI).

The present invention for a method and a corresponding network node as claimed in the accompanying claims.

Example embodiments will become more fully understood from the detailed description given herein below and the accompanying drawings, wherein like elements are represented by like reference numerals, which are given by way of illustration only and thus are not limiting of this disclosure.

Detailed illustrative embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. The example embodiments may, however, be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.

It should be understood that there is no intent to limit example embodiments to the particular forms disclosed. On the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of this disclosure. Like numbers refer to like elements throughout the description of the figures.

While one or more example embodiments may be described from the perspective of radio network elements (e.g., gNB), user equipment, or the like, it should be understood that one or more example embodiments discussed herein may be performed by the one or more processors (or processing circuitry) at the applicable device. For example, according to one or more example embodiments, at least one memory may include or store computer program code, and the at least one memory and the computer program code may be configured to, with at least one processor, cause a radio network element (or user equipment) to perform the operations discussed herein.

It will be appreciated that a number of example embodiments may be used in combination.

<FIG> illustrates a simplified diagram of a portion of a <NUM>rd Generation Partnership Project (3GPP) New Radio (NR) access deployment for explaining example embodiments. The 3GPP NR radio access deployment includes a base station (e.g., gNB <NUM>) having transmission and reception points (TRPs) 102A, 102B, 102C. Each TRP 102A, 102B, 102C may be, for example, a remote radio head (RRH) or remote radio unit (RRU) including at least, for example, a radio frequency (RF) antenna (or antennas) or antenna panels, and a radio transceiver, for transmitting and receiving data within a geographical area. In this regard, the TRPs 102A, 102B, 102C provide cellular resources for user equipment (UEs) within a geographical coverage area. In some cases, baseband processing may be divided between the TRPs 102A, 102B, 102C and gNB <NUM> in a 5th Generation (<NUM>) cell. Alternatively, the baseband processing may be performed at the gNB <NUM>. In the example shown in <FIG>, the TRPs 102A, 102B, 102C are configured to communicate with a UE (e.g., UE <NUM>) via one or more transmit (TX)/receive (RX) beam pairs. The gNB <NUM> communicates with the core network, which is referred to as the New Core in 3GPP NR.

The TRPs 102A, 102B, 102C may have independent schedulers, or the gNB <NUM> may perform joint scheduling among the TRPs 102A, 102B, 102C.

Although only a single UE <NUM> is shown in <FIG>, the gNB <NUM> and TRPs 102A, 102B, 102C may provide communication services to a relatively large number of UEs within the coverage area of the TRPs 102A, 102B, 102C. For the sake of clarity of example embodiments, communication services (including transmitting and receiving wireless signals) will be discussed as between the gNB <NUM> and the UE <NUM>. It should be understood, however, that signals may be transmitted between the UE <NUM> and one or more of the TRPs 102A, 102B, 102C.

<FIG> illustrates a block diagram of a gNB (shown in <FIG>), in accordance with an example embodiment. As shown, the gNB <NUM> includes: a memory <NUM>; a processor <NUM> connected to the memory <NUM>; various interfaces <NUM> connected to the processor <NUM>; and one or more antennas or antenna panels <NUM> connected to the various interfaces <NUM>. The various interfaces <NUM> and the antenna <NUM> may constitute a transceiver for transmitting/receiving data from/to the gNB <NUM> via a plurality of wireless beams or from/to the plurality of TRPs 102A, 102B, 102C, etc. As will be appreciated, depending on the implementation of the gNB <NUM>, the gNB <NUM> may include many more components than those shown in <FIG>. However, it is not necessary that all of these components be shown in order to disclose the illustrative example embodiment.

The memory <NUM> may be a computer readable storage medium that generally includes a random access memory (RAM), read only memory (ROM), and/or a permanent mass storage device, such as a disk drive. The memory <NUM> also stores an operating system and any other routines/modules/applications for providing the functionalities of the gNB <NUM> (e.g., functionalities of a gNB, methods according to the example embodiments, etc.) to be executed by the processor <NUM>. These software components may also be loaded from a separate computer readable storage medium into the memory <NUM> using a drive mechanism (not shown). Such separate computer readable storage medium may include a disc, tape, DVD/CD-ROM drive, memory card, or other like computer readable storage medium (not shown). In some example embodiments, software components may be loaded into the memory <NUM> via one of the various interfaces <NUM>, rather than via a computer readable storage medium.

The processor <NUM> may be configured to carry out instructions of a computer program by performing the arithmetical, logical, and input/output operations of the system. Instructions may be provided to the processor <NUM> by the memory <NUM>.

The various interfaces <NUM> may include components that interface the processor <NUM> with the antenna <NUM>, or other input/output components. As will be understood, the various interfaces <NUM> and programs stored in the memory <NUM> to set forth the special purpose functionalities of the gNB <NUM> will vary depending on the implementation of the gNB <NUM>.

The interfaces <NUM> may also include one or more user input devices (e.g., a keyboard, a keypad, a mouse, or the like) and user output devices (e.g., a display, a speaker, or the like).

Although not specifically discussed herein, the configuration shown in <FIG> may be utilized to implement, inter alia, the TRPs 102A, 102B, 102C, other radio access and backhaul network elements and/or devices. In this regard, for example, the memory <NUM> may store an operating system and any other routines/modules/applications for providing the functionalities of the TRPs, etc. (e.g., functionalities of these elements, methods according to the example embodiments, etc.) to be executed by the processor <NUM>.

<FIG> illustrates a block diagram of a user equipment (UE) <NUM>, in accordance with an example embodiment. The UE <NUM> is a device used by an end-user to communicate via the 3GPP NR radio access deployment shown in <FIG>. Examples of UEs include cellular phones, smartphones, tablet, computers, laptop computers, or the like.

As shown, the UE <NUM> includes: a memory <NUM>; a processor <NUM> connected to the memory <NUM>; various interfaces <NUM> connected to the processor <NUM>; and one or more antennas or antenna panels <NUM> connected to the various interfaces <NUM>. The various interfaces <NUM> and the antenna <NUM> may constitute a transceiver for transmitting/receiving data to/from the gNB <NUM> via a plurality of wireless beams or to/from the plurality of TRPs 102A, 102B, 102C, etc. As will be appreciated, depending on the implementation of the UE <NUM>, the UE <NUM> may include many more components than those shown in <FIG>. However, it is not necessary that all of these generally conventional components be shown in order to disclose the illustrative example embodiment.

The memory <NUM> may be a computer readable storage medium that generally includes a random access memory (RAM), read only memory (ROM), and/or a permanent mass storage device, such as a disk drive. The memory <NUM> also stores an operating system and any other routines/modules/applications for providing the functionalities of the UE <NUM> (e.g., functionalities of a UE, methods according to the example embodiments, etc.) to be executed by the processor <NUM>. These software components may also be loaded from a separate computer readable storage medium into the memory <NUM> using a drive mechanism (not shown). Such separate computer readable storage medium may include a disc, tape, DVD/CD-ROM drive, memory card, or other like computer readable storage medium (not shown). In some example embodiments, software components may be loaded into the memory <NUM> via one of the various interfaces <NUM>, rather than via a computer readable storage medium.

The various interfaces <NUM> may include components that interface the processor <NUM> with the antenna <NUM>, or other input/output components. As will be understood, the various interfaces <NUM> and programs stored in the memory <NUM> to set forth the special purpose functionalities of the UE <NUM> will vary depending on the implementation of the UE <NUM>.

At least some example embodiments are directed toward 3GPP New Radio (NR) physical layer developments. Specifically, the example embodiments pertain to physical layer procedures to facilitate power savings for the UE <NUM>, during times when the UE <NUM> is in a radio resource control (RRC) connected state with the serving gNB <NUM>.

The battery life of the UE <NUM> is an important aspect of a user's experience, as the battery life will influence an adoption of <NUM> NR handsets and/or services. Battery life is critical to specify techniques and designs to facilitate efficient means for power savings of the UE <NUM>, to ensure that power efficiency of the UE <NUM> for use in <NUM> NR be better than that of, for instance, long-term evolution (LTE).

In particular, energy efficiency within the following two aspects, is of critical importance: (a) efficient data transmission in a loaded case; and (b) low energy consumption when there is no data.

Example embodiments support NR systems for high speed data transport, where bursty user data would be served by a network in very short durations. One efficient power saving mechanism for the UE <NUM>, is to trigger the UE <NUM> for network access from a power efficient mode. The UE <NUM> would stay in the power efficient mode, such as a micro sleep, or an 'OFF' period, in a discontinue reception (DRX) cycle, that may be a short or long period of time, unless it the UE <NUM> is informed of a network access through the power saving framework for the UE <NUM>. Informing the UE <NUM> may be accomplished via a 'wake-up' procedure, in a 'RRC CONNECTED' state, where the UE <NUM> is configured to be in the power saving signal/channel, before the 'DRX ON' duration, to trigger the UE <NUM> to 'wake up' only when there is a downlink (DL) data arrival. Otherwise, the UE <NUM> is not required to wake up at the DRX ON, at least for purposes of physical downlink control channel (PDCCH) monitoring, if the power saving signal is not detected.

<FIG> illustrates a wake up signal (WUS) occasion <NUM>, in an example embodiment, with a one to one mapping of the WUS occasion with a next (or the on duration that is corresponding to the WUS occasion) on-duration. In one example embodiment, the WUS occasion <NUM> (e.g., UE <NUM> reception of a wake up signal) is, for example, a PDCCH based power saving indication, that is configured together with a DRX configuration, where a presence of the signal/channel determines whether the UE <NUM> is required to monitor PDCCH (according to normal search space configuration), during the next 'On Duration' <NUM>, or in other words, during occurrence of a next (or the corresponding or the associated occurrence of the) 'OnDurationTimer'. In one example, the WUS may control UE to start the drx-onduration timer for the corresponding on duration of the DRX cycle. There may be one to one mapping of WUS occasion or occasions and drx-on duration or one or more WUS occasions may control the start of on duration timer for multiple occurrences of DRX on duration timer. In an example embodiment, the UE <NUM> is configured to monitor PDCCH based on a wake-up signal (WUS), which is be referred to as the wake up signal occasion <NUM>, where the UE <NUM> may for example conduct this monitoring by using a certain downlink control information (DCI) format, such as a power saving downlink control information (PS-DCI) format, before the 'onDuration' <NUM>, in order to trigger the UE <NUM> monitoring during the 'onDuration' <NUM>. This downlink control (DC) may be scrambled with a power saving radio network temporary identifier (PS-RNTI). WUS, or wake-up signal, may be referred also as DCI format with CRC scrambled using PS-RNTI (power saving RNTI), power saving indication, wake-up indication or PDCCH-WUS or indication to start on duration timer in the next (or the corresponding) occurrence of drx-onDurationtimer or power save indication (PSI).

A protocol architecture for <NUM> NR includes protocol layers 500a/b that include: a protocol stack <NUM> for the gNB <NUM>; and a user plane 500b for the UE <NUM>. These protocol layers 500a/b share similarities, and communication with each other. The protocol layers 500a/b include: a physical (PHY) layer 502a/b that is a first and lowest layer that includes electronic circuit transmissions and underlies higher level network functions; a media access control (MAC) layer 504a/b is a sublayer that controls hardware responsible for interaction with wired, optical or wireless transmission medium, and which is a sublayer that offers logical channels to the next highest layer (i.e., RLC); a radio link control (RLC) layer 506a/b that accepts logical channels from the MAC 504a/b; a packet data convergence protocol (PDCP) layer 508a/b, that offers radio bearers to the next highest level (i.e., SDAP); and a service data adaptation protocol (SDAP) layer 510a/b that accepts the radio bearers from PDCP 508a/b.

In an example embodiment, the power savings method disclosed in <FIG>, pertains to power savings for the UE <NUM> that is performed at the physical layer 502b.

The instant example embodiment includes a concept of a 'timing advance group. ' In an example embodiment, this is a group of Serving Cells that are configured by radio resource control (RRC) that, for the cells with uplink (UL) configured, use a same timing reference cell and a same timing advance value. In an example embodiment, a Timing Advance Group contains a SpCell of a MAC entity, which may be referred to as a Primary Timing Advance Group (PTAG), whereas a Secondary Timing Advance Group (STAG) refers to other Timing Advance Groups (TAGs).

A maintenance of uplink time alignment is supervised by the MAC layer 504a/b (see <FIG>) using a RRC configured time alignment timer (referred to as 'timeAlignmentTimer (TAT). ' In an example embodiment, when the TAT is running, the UE <NUM> can consider itself uplink time aligned. The UE <NUM> may lose the time alignment, for example, when there is no communication in UL or DL for a while, and the TAT expires.

In an example embodiment, the WUS is configured to be received and processed by the processor <NUM> of the UE <NUM>, so that the UE <NUM> monitors the physical downlink control channel (PDCCH), prior to a start of the on duration <NUM> (see <FIG>) of the DRX cycle, to determine whether the WUS indicates that the UE <NUM> is to wake up for the next (or corresponding) on duration <NUM>. That is to say, the processor <NUM> of the UE <NUM> determines whether to start 'onDurationTimer' and monitor the PDCCH.

In an example embodiment, as the expiry prevents the UE <NUM> from performing any other transmission (or, when the UE <NUM> cannot consider itself to be uplink timer aligned anymore), other than random access, the UE <NUM> needs to wait until a network triggers the processor <NUM> of the UE <NUM> to perform random access (i.e., PDCCH order), or the UE <NUM> initiates a contention based random access when the UE <NUM> determines that it has UL data in the memory <NUM> (e.g., buffer).

The example embodiments complete this procedure in an efficient manner to improve communication latency and power saving for the UE <NUM>.

In an example embodiment, the PDCCH monitoring activity of the UE <NUM>, in a radio resource control (RRC) connected mode, is governed by a discontinue reception DRX framework. In an example embodiment, when DRX is configured, the UE <NUM> does not have to continuously monitor PDCCH. DRX is characterized by the following:.

OnDuration: the 'on duration' <NUM> (<FIG> and <FIG>) is a duration that the UE <NUM> waits for, after waking up, to receive PDCCHs. If the UE <NUM> successfully decodes a PDCCH, the UE <NUM> stays awake and starts an inactivity timer.

Inactivity-timer: a duration that the UE <NUM> waits to successfully decode a PDCCH, from the last successful decoding of a PDCCH, where the UE <NUM> will go back to sleep if this fails. In an example embodiment, the UE <NUM> shall restart the inactivity timer following a single successful decoding of a PDCCH event that schedules transmission of uplink (UL) or downlink (DL) data (for a first transmission only, i.e. not for retransmissions).

Retransmission-timer: a duration until a retransmission can be expected.

Cycle: this cycle, or DRX cycle <NUM> (<FIG>), specifies a periodic repetition of the on-duration <NUM> (<FIG>), followed by a possible period of inactivity (see <FIG>).

Active time: total duration that the UE <NUM> monitors PDCCH. This time includes the "on-duration" <NUM> of the DRX cycle <NUM>, the time the UE <NUM> is performing continuous reception while the inactivity timer has not expired, and the time when the UE <NUM> is performing continuous reception while waiting for a retransmission opportunity.

Furthermore, as discussed above, the UE <NUM> may be configured to monitor PDCCH based a wake-up signal (WUS), for certain DCI formats before the onDuration <NUM>, in order to trigger the monitoring by the UE <NUM> during onDuration <NUM>.

The 3GPP definition of QCL (quasi co-location) is that two antenna ports are said to be quasi co-located if properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. When two different signals share the same QCL type, they share the same indicated properties. As an example, the QCL properties may be e.g. delay spread, average delay, doppler spread, doppler shift, spatial RX. QCL type A means Doppler spread, Doppler shift, delay spread, and/or average delay, and QCL type D means spatial RX. Currently <NUM> lists following QCL types:.

As a further example if a CSI-RS and SSB have the type D QCL assumption between each other, it means that UE may utilize same RX spatial filter (beam) to receive these signals.

The example embodiment includes methods to quickly enable the processor <NUM> of the UE <NUM> to obtain time alignment to respond to WUS <NUM>, when the network is configured to utilize WUS <NUM> to wake up the UE <NUM>.

In one example embodiment, an indication to perform a random access channel (RACH) procedure is provided for power saving specific to downlink (DL) signaling. This indication may include any of following alternatives:.

First Major Embodiment: In first example embodiment, when the UE <NUM> has determined that its TAT has expired, and the UE <NUM> is configured to monitor for WUS occasion(s) <NUM>, the UE <NUM> searches additionally the DCI format for a PDCCH ordered RACH (if the CRC of the DCI format 1_0 is scrambled by a cell radio network temporary identifier, or C-RNTI, and a "Frequency domain resource assignment" field are of all ones), for an indication to perform a contention free RACH procedure. The network may transmit the DCI (that triggers PDCCH order), in the PDCCH based power saving channel. If the UE <NUM> has a valid timing advance (TA), the UE <NUM> is not required to monitor the DCI format in the WUS / search space where it monitors the power saving DCI format (PS-DCI) or Power saving PDCCH search space. For scrambling the DCI format for PDCCH ordered RACH, the power saving radio network temporary identifier (PS-RNTI) or C-RNTI may be used.

Second Major Embodiment: In a second example embodiment, the PS-DCI (power saving DCI) format, which is a field that is used to indicate whether the UE <NUM> shall trigger RACH procedure to obtain UL timing advance. This field may be <NUM>-bit (or n-bit) field to indicate the UE <NUM> shall initiate RACH procedure. The field may implicitly indicate to the UE <NUM> to start onDurationTimer (monitor PDCCH) after completion of the RACH procedure. The RACH procedure may be one of a contention based random access (CBRA) or contention free random access (CFRA).

In one alternative embodiment, of this second embodiment, a new additional DCI format, providing a PDCCH order for RACH, may be used, and the new additional DCI format can be sent using a PS-RNTI.

Third Major Embodiment: In a third example embodiment, the network may pre-configure the UE <NUM> with a CFRA PRACH resource, or resources and to trigger the PDCCH order to those resources. The triggering may be provided in the power saving downlink control information (PS-DCI)/WUS/DCI format with CRC scrambled. As an implementation of this third embodiment, three options are described below.

Option <NUM>: If a <NUM> (one) bit signaling is used (or, any indication that is not explicitly triggering the CFRA procedure with explicit resource allocation), in an example embodiment the UE <NUM> may be configured with one dedicated PRACH resource. Alternatively, if the <NUM> (one) bit signaling is used (or any indication that is not explicitly triggering the CFRA procedure with explicit resource allocation), and the UE <NUM> has been configured with multiple CFRA resources, the UE <NUM> selects one of the resources to initiate RACH procedure. UE may select one of the resources that has RSRP/RSRQ/SINR above a network configured threshold level. In an example embodiment, UE may select or prioritize the selection of the CFRA resource (or CBRA resource in case CFRA resources are not suitable based on the signal quality threshold wherein the signal quality threshold may be optional) that corresponds to a downlink reference signal (DL RS) that is spatially quasi co-located (QCL) with; the PDCCH DMRS (i.e. DL RS that correspond to the PDCCH beams) during active time (i.e. when UE is monitoring PDCCH according to search space configuration), DL RS corresponding any of the transmission configuration indicator (TCI) states for PDCCH/PDSCH/PUCCH/PDSCH or with the PDCCH DMRS used to transmit the WUS.

Option <NUM>: In this option, no explicit trigger is provided, and when the UE <NUM> detects the WUS transmission <NUM> in the monitored occasion, and the UE <NUM> determines that it does not have a valid TA, so the UE <NUM> triggers PRACH on the configured CFRA PRACH resource or resources. In one alternative, UE may trigger contention based random access procedure in case the CFRA resource is not configured, or use of CFRA resources are not considered in the implicit triggering.

Option <NUM>: In this option, the network triggers one or more of the pre-configured CFRA PRACH resources with explicit signaling (e.g., a logical index in the set of PRACH preambles e.g. in form of a bitmap or explicit index), where the UE <NUM> shall trigger the CFRA PRACH. In case multiple resources are indicated UE may select one of the resources. In some cases the selection may be determined based on signal quality threshold based on the corresponding DL RS.

Fourth Major Embodiment: In one additional embodiment, when the PRACH procedure is triggered, and the WUS is configured, the UE <NUM> shall prioritize PRACH resources that correspond to the DL RS that is quasi co-located (QCL) e.g. in terms of spatial RX with the active time PDCCH TCI states, or with DL RS that is QCL with PDCCH demodulation reference signal (DMRS) that was used to transmit the wake up signal (where the UE <NUM> successfully detects the WUS transmission <NUM>). The triggered RACH procedure may be CBRA or CFRA.

In the embodiments above, the UE <NUM> monitors the DCI format for PDCCH ordered random access procedure using the power saving radio network temporary identifier (PS-RNTI). In some cases UE may monitor the said DCI format using PS-RNTI or C-RNTI or both.

In any of the embodiments herein, network may trigger either contention based or contention free random access procedure using a specific DCI format or using an indication in the PS-DCI format.

In any of the embodiments herein, the indication to initiate RACH procedure using specific random access preamble resource (either CFRA/CBRA) may be a logical index (based on preconfigured set) or it may be an explicit index of a RACH resource.

In one example embodiment, in any of the embodiments herein, network may indicate UE to initiate random access procedure without instructing UE to wake up to monitor PDCCH during the on duration (e.g. start the drx-ondurationTimer to monitor PDCCH).

In an example embodiment, when the group based WUS signal is configured and it indicates UE to wake up, the UE <NUM> determines if the TAT has expired, and will then trigger a RACH procedure (using potentially preconfigured RACH resources or CBRA).

In an alternative example embodiment, the trigger to initiate RACH procedure may be implicit. When the UE is configured to monitor power saving downlink control information (wake up signal/wake up indication) and it indicates UE to wake up, the UE <NUM> determines if the TAT has expired, and will then trigger a RACH procedure (using potentially preconfigured RACH resources or CBRA). For triggering the RACH procedure UE may use any of the methods in any of the embodiments herein.

<FIG> illustrates a method of power saving for the UE <NUM>, in an example embodiment. In an example embodiment, this method includes a set of computer-readable instructions that are saved to the memory <NUM> of the UE <NUM> (see <FIG>), where the processor <NUM> of the UE <NUM> performs these instructions at the physical layer 502b of the UE <NUM> (see <FIG>). In an example embodiment, the UE <NUM> uses a wake up signal (WUS) <NUM> within the framework of a discontinue reception (DRX) cycle <NUM> (<FIG>), to save power. In the event of expiry or loss of the uplink time alignment timer (TAT), the processor <NUM> of the UE <NUM> will cause the UE <NUM> to wait before performing a random access procedure (RACH). During this wait period, and without the use of WUS <NUM>, conventionally the power of the UE <NUM> would be consumed even though the UE <NUM> is not actively transmitting / receiving data with the gNB <NUM>. Specifically, using a conventional DRX cycle <NUM> without WUS <NUM>, a conventional network would configure the TAT to ensure it is not shorter than the duration of the DRX cycle <NUM>, meaning that the TAT would not expire when the UE <NUM> is sleeping (for instance, according to 3GPP standard TS <NUM>, the TAT is <NUM>-<NUM> seconds). However, by using WUS <NUM> in the example embodiment of <FIG>, multiple DRX cycles <NUM> may be skipped (e.g., multiple 'on duration' periods <NUM> may be skipped), thus allowing the TAT to expire, even though the TAT may be longer than a single, or multiple, DRX cycles <NUM>. This method therefore reduces unproductive and/or power consumption by the UE <NUM>, by ensuring that a time alignment is quickly obtained. Based on this general explanation, the method of <FIG> is described in detail below.

At the outset of the method of <FIG>, it is presumed that the processor <NUM> of the UE <NUM> is arranged to communicate with the memory <NUM>, where the memory <NUM> includes computer-readable instructions that configure the processor <NUM> to monitor the power savings channel of the PDCCH for the wake up signal <NUM> (<FIG>), so that the wake up signal <NUM> can notify the processor <NUM> of a start time for the "on duration" <NUM> (where the "on duration" <NUM>) is used in step S604. The steps of <FIG> are performed at the UE <NUM>.

As shown in <FIG>, at step S600, the processor <NUM> of the UE <NUM> determines if the UE <NUM> is time aligned with at least one gNB <NUM>. This can for instance be accomplished by the processor <NUM> determining if the timeAlignmentTimer for the UE <NUM> has expired. If the UE <NUM> is time aligned, then in step S602 the processor <NUM> monitors the PDCCH for the power saving downlink control information (PS-DCI) format for the at least one gNB <NUM>.

If the UE is not time aligned, then in step S604 the processor <NUM> searches the power saving DCI format in the power saving search space and additionally the DCI format for PDCCH ordered RACH (in the same search space where it searches the PS-DCI), to determine if the cyclic redundancy check (CRC) of the DCI format 1_0 is scrambled by PS-RNTI and the "frequency domain resource assignment" field are of all ones for an indication to perform contention free RACH procedure.

In step S606, the processor <NUM> performs a RACH procedure. In an example embodiment, the RACH procedure is performed in response to determining that the UE <NUM> is triggered by PDCCH ordered RACH, and the processor <NUM> determines based on the power saving DCI whether to enter active time i.e. start the onDurationTimer on the next or the corresponding occurrence (of the timer). In an example embodiment, the DCI format to trigger PDCCH ordered RACH is scrambled by C-RNTI or PS-RNTI.

As discussed herein, illustrative embodiments will be described with reference to acts and symbolic representations of operations (e.g., in the form of flow charts, flow diagrams, data flow diagrams, structure diagrams, block diagrams, etc.) that may be implemented as program modules or functional processes include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types and may be implemented using existing hardware at, for example, existing user equipment, base stations, eNBs, RRHs, gNBs, femto base stations, network controllers, computers, or the like. Such existing hardware may be processing or control circuitry such as, but not limited to, one or more processors, one or more Central Processing Units (CPUs), one or more controllers, one or more arithmetic logic units (ALUs), one or more digital signal processors (DSPs), one or more microcomputers, one or more field programmable gate arrays (FPGAs), one or more System-on-Chips (SoCs), one or more programmable logic units (PLUs), one or more microprocessors, one or more Application Specific Integrated Circuits (ASICs), or any other device or devices capable of responding to and executing instructions in a defined manner.

As disclosed herein, the term "storage medium," "computer readable storage medium" or "non-transitory computer readable storage medium" may represent one or more devices for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other tangible machine-readable mediums for storing information. The term "computer-readable medium" may include, but is not limited to, portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing or carrying instruction(s) and/or data.

Furthermore, example embodiments may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine or computer readable medium such as a computer readable storage medium. When implemented in software, a processor or processors will perform the necessary tasks. For example, as mentioned above, according to one or more example embodiments, at least one memory may include or store computer program code, and the at least one memory and the computer program code may be configured to, with at least one processor, cause a network element or network device to perform the necessary tasks. Additionally, the processor, memory and example algorithms, encoded as computer program code, serve as means for providing or causing performance of operations discussed herein.

A code segment of computer program code may represent a procedure, function, subprogram, program, routine, subroutine, module, software package, class, or any combination of instructions, data structures or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable technique including memory sharing, message passing, token passing, network transmission, etc..

The terms "including" and/or "having," as used herein, are defined as comprising (i.e., open language). The term "coupled," as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. Terminology derived from the word "indicating" (e.g., "indicates" and "indication") is intended to encompass all the various techniques available for communicating or referencing the object/information being indicated. Some, but not all, examples of techniques available for communicating or referencing the object/information being indicated include the conveyance of the obj ect/information being indicated, the conveyance of an identifier of the object/information being indicated, the conveyance of information used to generate the object/information being indicated, the conveyance of some part or portion of the object/information being indicated, the conveyance of some derivation of the object/information being indicated, and the conveyance of some symbol representing the object/information being indicated.

According to example embodiments, user equipment, base stations, eNBs, RRHs, gNBs, femto base stations, network controllers, computers, or the like, may be (or include) hardware, firmware, hardware executing software or any combination thereof. Such hardware may include processing or control circuitry such as, but not limited to, one or more processors, one or more CPUs, one or more controllers, one or more ALUs, one or more DSPs, one or more microcomputers, one or more FPGAs, one or more SoCs, one or more PLUs, one or more microprocessors, one or more ASICs, or any other device or devices capable of responding to and executing instructions in a defined manner.

Claim 1:
A method, comprising:
performing, by at least one processor of a user equipment, UE, at least one first monitoring of a power savings channel of a physical downlink control channel, PDCCH, for control information, the PDCCH being associated with at least one base station, the control information including a power saving downlink control information, PS-DCI, format, the control information providing an indication to start a timer for an ON duration of a discontinuous reception, DRX, cycle for the UE to monitor the PDCCH;
performing, by the at least one processor, a random-access channel, RACH, procedure with the at least one base station based on the control information;
determining, by the at least one processor, if the UE is not uplink time aligned with at least one cell; and
performing, by the at least one processor, a second monitoring of the PDCCH for indication information, if the UE is not uplink time aligned,
the indication information including an indication that the UE is to initiate a random-access channel, RACH, procedure.