System and method for wireless carriers

Abstract

A network entity, NE, transmits a first plurality of DL transmissions with a first periodicity during an initial access procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information that indicates a second transmission resource for a second DL transmission of second configuration information. The NE transmits the second DL transmission of the second configuration information using the second transmission resource in accordance with the first configuration information during the initial access procedure.

Description

System and Method for Wireless CarriersCROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application claims priority to U.S. Provisional Application No. 63 / 643,686, filed on May 7, 2024, and entitled “System and Method for Wireless Carriers,” application of which is hereby incorporated by reference herein as if reproduced in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to w ireless communications, and, in particular embodiments, to systems and methods for wireless carriers.BACKGROUND

[0003] Wireless communication systems include long term evolution (LTE), LTE-A, LTE-A-beyond systems, 5th generation (5G) LTE, 5G New Radio (NR), 6th generation (6G), etc. It is widely observed that carrier design in the current 5G NR systems consumes a considerably high amount of energy. In many cases, due to the increased bandwidth (BW) and the number of antennas such as in a multiple-input multipleoutput (MI MO) or massive MI MO network, the current NR systems may operate with even lower energy efficiency than that of the LTE systems. As 6G is to be developed, and as even wider BW and more massive MIMO antenna systems are considered for 6G, energy efficiency becomes a major technical challenge, and it is desirable to improve the energy efficiency for 6G systems and beyond, for both the network side and the UE side, starting from the carrier design. In addition, the basic 4G and 5G frequency-domain system design unit is a carrier, and the approach to incorporate a wider bandwidth is to essentially apply a single-carrier design (most of the operations, signaling, signals and channels, etc.) to multiple carriers, leading to complex operations, high signaling overhead, slow protocols, etc. So, it is desirable to provide new approaches with better scalability properties for carrier design. Overall, the goal is to provide new designs that are scalable, flexible, and energy-efficient to incorporate any number of carrier resources of all types.

[0004] A modern wireless communication system may include a plurality of NodeBs (NBs), which may also be referred to as base stations, network nodes, communications controllers, cells, or enhanced NBs (eNBs), and so on. A NodeB may include one or more network points or network nodes using different radio access technologies (RATs) such-i-as high speed packet access (HSPA) NBs or WiFi access points. A NodeB may be associated with a single network point or multiple network points. A cell may include a single network point or multiple network points, and each network point may have a single antenna or multiple antennas. A network point may correspond to multiple cells operating in multiple component carriers. Generally, each component carrier in carrier aggregation is a serving cell, either a primaiy cell (PCell) or a secondary cell (SCell) .

[0005] A cell or NodeB (NB) may serve a number of users (also commonly referred to as user equipments (UEs), mobile stations, terminals, devices, and so on) over a period of time. A communication channel from a NB to a UE is generally referred to as a downlink (DL) channel, and a transmission from the NB to the UE is a downlink transmission. A communication channel from a UE to a NB is generally referred to an uplink (UL) channel, and a transmission from the UE to the NB is an uplink transmission. NR UEs may also support sidelink communication between two or more nearby UEs, using NR technology but not traversing any network node.

[0006] The downlink (DL) waveform in 5G NR uses conventional OFDM with a cyclic prefix (CP), while the uplink (UL) waveform uses conventional OFDM with a CP and a transform precoding function that performs Discrete Fourier Transform (DFT) spreading. Downlink and uplink transmissions are organized into frames (e.g., radio frames) w ith 10 ms duration, consisting of ten 1 ms subframes. Each frame is divided into two equally sized half-frames of five subframes each. The slot duration is 14 symbols with the Normal CP and 12 symbols with the Extended CP (ECP), and scales in time as a function of the used subcarrier spacing (SCS) so that there is always an integer number of slots in a subframe.

[0007] For a receiver in the UE to be able to demodulate a downlink (DL) transmission, the receiver can be synchronized with the gNB (transmitter). Therefore, a UE can synchronize with the gNB numerology (frame, slots, and symbols). The synchronization is achieved in 5G NR via acquiring by a UE of the synchronization signal (SS) and PBCH block (SSB).SUMMARY

[0008] Technical advantages are generally achieved, by implementations of this disclosure which describe methods, apparatus, and system.

[0009] In accordance w ith implementations, a network entity transmits a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration informationindicates a second transmission resource for a second DL transmission of second configuration information. The network entity transmits the second DL transmission of the second configuration information using the second transmission resource in accordance w ith the first configuration information during the initial access procedure.

[0010] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted with a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is transmitted.

[0011] In some implementations, the second periodicity may be an N multiple of the first periodicity. N may be an integer greater than 1.

[0012] In some implementations, the first configuration information may further indicate a first time or frequency domain resource for a first UL transmission. The network entity may receive the first UL transmission including a first UL sequence on the first time or frequency domain resource. To transmit the second DL transmission, the network entity may transmit the second DL transmission of the second configuration information in response to the receiving the first UL transmission.

[0013] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the timedomain signal transmission.

[0014] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission maybe received in a WUS monitoring window in accordance with the WUS monitoring window information.

[0015] In some implementations, the first configuration information may indicate the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0016] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted with a second periodicity. The firstconfiguration information may include an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

[0017] In some implementations, values of the indicator in the first plurality of DL transmissions may be in a sequentially decreasing order of (N-1, 1, o). N may be an integer greater than 1. The network entity may reset the indicator to a different value than a current value of the indicator.

[0018] In some implementations, the first configuration information may indicate the second transmission resource by indicating a second time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0019] In some implementations, after the transmitting the second DL transmission, the network entity may receive a random access (RA) preamble in a physical random access channel in accordance w ith the second configuration information or transmit a third DL transmission of third configuration information. The third DL transmission may include a higher payload or is configured with a longer periodicity than the second DL transmission.

[0020] In some implementations, the first configuration information may include only minimum information for the UE to obtain the second DL transmission of the second configuration information.

[0021] In some implementations, the first configuration information may only indicate the second transmission resource and may be accompanied only by a demodulation reference signal (DMRS) and a cyclic redundancy check (CRC).

[0022] In some implementations, the first plurality of DL transmissions may include a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence. The first configuration information may be between the first PSS and the second PSS in the time domain.

[0023] In some implementations, the network entity may include a plurality of base stations.

[0024] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0025] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0026] In accordance with implementations, a network entity transmits a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a first time or frequency domain resource for a first UL transmission and a second transmission resource for a second DL transmission of second configuration information. The network entity transmits the second DL transmission of the second configuration information using the second transmission resource in response to receiving the first UL transmission.

[0027] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the timedomain signal transmission.

[0028] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission may be received in a WUS monitoring window in accordance with the WUS monitoring window information. The first configuration information may exclude information indicating a transmission occasion of the second DL transmission of the second configuration information.

[0029] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0030] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0031] In accordance with implementations, a UE receives a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure or a cell search procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a second transmission resource for a second DL transmission of second configuration information. The UE performs at least one of time synchronization or frequency synchronization based on the first synchronization sequence. The UE receives the second DL transmission of the second configuration information using thesecond transmission resource in accordance w ith the first configuration information during the initial access procedure,

[0032] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted with a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is received.

[0033] In some implementations, the second periodicity may be an N multiple of the first periodicity. N may be an integer greater than 1.

[0034] In some implementations, the first configuration information may further indicate a first time or frequency domain resource for a first UL transmission. The UE may transmit the first UL transmission including a first UL sequence on the first time or frequency domain resource. The UE may receive the second DL transmission of the second configuration information in response to the transmitting the first UL transmission.

[0035] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying the UE transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission.

[0036] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission maybe transmitted in a WUS monitoring window in accordance with the WUS monitoring window information.

[0037] In some implementations, the first configuration information may indicate the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0038] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions received with a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

[0039] In some implementations, values of the indicator in the first plurality of DL transmissions may be in a sequentially decreasing order of (N-l, 1, o). N may be an integer greater than 1. The indicator may be reset to a different value than a current value of the indicator.

[0040] In some implementations, the first configuration information may indicate the second transmission resource by indicating a second time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0041] In some implementations, after receiving the second DL transmission, the UE may transmit a random access (RA) preamble in a physical random access channel in accordance with the second configuration information or receive a third DL transmission of third configuration information. The third DL transmission may include a higher payload or is configured with a longer periodicity than the second DL transmission.

[0042] In some implementations, the first configuration information may include only minimum information for the UE to obtain the second DL transmission of the second configuration information.

[0043] In some implementations, the first configuration information may only indicate the second transmission resource and may be accompanied only by a demodulation reference signal (DMRS) and a cyclic redundancy check (CRC).

[0044] In some implementations, the first plurality of DL transmissions may include a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence. The first configuration information may be between the first PSS and the second PSS in the time domain.

[0045] In some implementations, the first plurality of DL transmissions may be received from a network entity. The network entity may include a plurality of base stations.

[0046] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0047] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0048] In accordance with implementations, a UE receives a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure or a cell search procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configurationinformation indicates a first time or frequency domain resource for a first UL transmission and a second transmission resource for a second DL transmission of second configuration information. The UE performs at least one of time synchronization or frequency synchronization based on the first synchronization sequence. The UE receives the second DL transmission of the second configuration information using the second transmission resource in response to transmitting the first UL transmission during the initial access procedure.

[0049] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the timedomain signal transmission.

[0050] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission may be transmitted in a WUS monitoring window in accordance with the WUS monitoring window information. The first configuration information may exclude information indicating a transmission occasion of the second DL transmission of the second configuration information.

[0051] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0052] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0053] The disclosed techniques provide a multi-stage solution to wireless carrier design that significantly reduces energy consumption in the wireless networks while maintaining low latency. By transmitting lightweight synchronization signals frequently but reserving heavier configuration data for less frequent or on-demand transmission, the disclosed techniques enable devices to make informed power-saving decisions. The disclosed techniques improve the traditional always-on broadcasting w ith a flexible framework where a small amount of information is delivered through a combination of periodic transmissions w ith different periodicities and on-demand transmissions triggered by wake-up signals. The disclosed techniques achieve both network and device energy efficiency without sacrificing performance.BRIEF DESCRIPTION OF THE DRAWINGS

[0054] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0055] FIG. 1A shows illustrates an example wireless communication system, in accordance with some implementations;

[0056] FIG. 1B illustrates the example use of carrier aggregation (CA), in accordance with some implementations;

[0057] FIG. 2A shows an example of SS bursts multiplexed with PBCH, in accordance with some implementations;

[0058] FIG. 2B shows an example of signals multiplexed for more than one UE, in accordance with some implementations;

[0059] FIG. 2C shows an example of NZP CSI-RS used for channel estimation, in accordance with some implementations;

[0060] FIG. 3A shows an example of QCL assumptions among NR reference signals when wide beams are used, in accordance with some implementations;

[0061] FIG. 3B shows an example of QCL assumptions among NR reference signals when narrow beams are used, in accordance with some implementations;

[0062] FIG. 3C shows an example time-frequency structure of an SSB, in accordance with some implementations;

[0063] FIG. 3D shows an example of SSB Time distribution, in accordance with some implementations;

[0064] FIG. 3E shows an example SSB time distribution with 20 ms periodicity and SSB burst within 5 ms, in accordance with some implementations;

[0065] FIG. 4 illustrates an example of network transmission of the RA configuration after receiving the WUS, in accordance with some implementations;

[0066] FIG. 5 illustrates an example of the RA configuration in next opportunity after receiving the WUS, in accordance with some implementations;

[0067] FIG. 6 illustrates an example of multiple transmissions of the RA configuration after receiving the WUS, in accordance with some implementations;

[0068] FIG. 7 shows an example flowchart to set the RA transmission indicator, in accordance with some implementations;

[0069] FIG. 8 illustrates an example of multiple sets of SSBs w ith multiple periodicities, in accordance with some implementations;

[0070] FIG. 9 shows an example of a PSS validity area, in accordance with some implementations;

[0071] FIG. to illustrates an example of contiguous PSS / MMIB symbols with M ( >2) PSS symbols, in accordance with some implementations;

[0072] FIG. it illustrates an example of new SSB structure time multiplexed with legacy SSB, in accordance with some implementations;

[0073] FIG. 12 shows examples of PSS+SSS combination indicating either the WUS or MMIB occasion in the current period, in accordance with some implementations;

[0074] FIG. 13 illustrates an example of the UE behavior for MMIB monitoring orMMIB request via the UL WUS, in accordance with some implementations;

[0075] FIG. 14 illustrates an example of the multi-stage procedure, in accordance with some implementations;

[0076] FIG. 15 shows examples of the multi-stage WUS procedure, on-demand + periodic RA configuration procedure, and on-demand + periodic SIB procedure, in accordance with some implementations;

[0077] FIG. 16 illustrates an example flowchart implementations with the parameters and transmissions involving the multi-stage WUS procedure, on-demand + periodic RA configuration procedure, and on-demand + periodic SIB procedure, in accordance with some implementations;

[0078] FIG. 17 illustrates another example of the multi-stage procedure, in accordance with some implementations;

[0079] FIG. 18 illustrates an example of network transmission of the RA configuration after receiving the WUS, in accordance with some implementations;

[0080] FIG. 19 illustrates another example of the multi-stage procedure, in accordance with some implementations;

[0081] FIG. 20 illustrates an example of network transmission of the RA configuration after receiving the WUS, in accordance with some implementations;

[0082] FIG. 21 illustrates another example of the multi-stage procedure, in accordance with some implementations;

[0083] FIG. 22A shows a flowchart of a method performed by a network entity, in accordance w ith some implementations;

[0084] FIG. 22B shows a flowchart of a method performed by a network entity, in accordance w ith some implementations;

[0085] FIG. 22C shows a flowchart of a method performed by a UE, in accordance with some implementations;

[0086] FIG. 22D shows a flowchart of a method performed by a UE, in accordance with some implementations;

[0087] FIG. 23 illustrates an example communication system, in accordance with some implementations;

[0088] FIGs. 24A and 24B illustrate example devices, in accordance with some implementations; and

[0089] FIG. 25 shows a block diagram of a computing system, in accordance with some implementations.

[0090] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherw ise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.DETAILED DESCRIPTIONS

[0091] FIG. 1A illustrates an example wireless communication system too.Communication system too includes a base station 110 with coverage area 101. The base station 110 sen es a plurality of user equipments (UEs), including UEs 120.Transmissions from the base station no to a UE is referred to as a downlink (DL) transmission and occurs over a downlink channel (shown in FIG. 1A as a solid arrowed line 135), while transmissions from a UE to the base station no is referred to as an uplink (UL) transmission and occurs over an uplink channel (shown in FIG. 1A as a dashed arrowed line 130). Data carried over the uplink / downlink connections may include data communicated between the UEs 120, as well as data communicated to / from a remote-end (not shown) by way of a backhaul network 115. Example downlink channels and signals include synchronization signal (SS) blocks, also called SS / physical broadcast channel (PBCH) block SS / PBCH block (SSB), physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), channel state information reference signal (CSI-RS) which includes tracking RS (TRS, aka CSI-RS for tracking), etc. Example uplink channels and signals include physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), an uplink sounding reference signal (SRS), orphysical random access channel (PRACH). The transmissions may be periodic, semi- persistent, or aperiodic. For example, P TRS stands for periodic TRS, AP TRS stands for aperiodic TRS, SP CSI-RS stands for semi-persistent CSI-RS, P SSB / SP SSB / AP SSB stand for periodic- / -semi-persistent / aperiodic SSB, and so on. Sendees may be provided to the plurality of UEs by service providers connected to the base station no through the backhaul network 115, such as the Internet. The wireless communication system too may include multiple distributed access nodes 110.

[0092] In a typical communication system, there are several operating modes. In a cellular operating mode, communications to and from the plurality of UEs go through the base station 110, while in device to device communications mode, such as proximity services (ProSe) operating mode, for example, direct communication between UEs is possible. As used herein, the term “base station” refers to any component (or collection of components) configured to provide wireless access to a network. Base stations may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, access nodes, access points (APs), transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, relays, customer premises equipment (CPE), the network side, the network, and so on. In the present disclosure, the terms “base station” and “TRP” are used interchangeably unless otherwise specified. As used herein, the term “UE” refers to any component (or collection of components) capable of establishing a wireless connection with a base station. UEs may also be commonly referred to as mobile stations, mobile devices, mobiles, terminals, user terminals, users, subscribers, stations, communication devices, CPEs, relays, Integrated Access and Backhaul (IAB) relays, and the like. It is noted that when relaying is used (based on relays, picos, CPEs, and so on), especially multi-hop relaying, the boundary’ between a controller and a node controlled by the controller may become blurry, and a dual node (e.g., either the controller or the node controlled by the controller) deployment w here a first node that provides configuration or control information to a second node is considered to be the controller. Likewise, the concept of UL and DL transmissions can be extended as well.

[0093] A cell may include one or more bandwidth parts (BWPs) for UL or DL allocated for a UE. Each BWP may have its own BWP-specific numerology and configuration, such as the BWP’s bandwidth. Not all BWPs need to be active at the same time for the UE. A cell may correspond to one carrier, and in some cases, multiple carriers. Typically, one cell (a primary cell (PCell) or a secondary cell (SCell), forexample) is a component carrier (a primary component carrier (PCC) or a secondary CC (SCC), for example). For some cells, each cell may include multiple carriers in UL, one carrier may be referred to as a UL carrier or non-supplementaiy UL (non-SUL, or simply UL) carrier which has an associated DL, and other carriers are called supplementary UL (SUL) carriers which do not have an associated DL. A cell, or a carrier, may be configured with slot or subframe formats comprising DL and UL symbols. In general, for unpaired spectrum, the cells or carriers are in a time division duplexed (TDD) mode, and for paired spectrum, the cells or carrier are in a frequency’ division duplexed (FDD) mode. For TDD mode, the same spectrum resources can be used for UL or DL at different time durations, where the time durations allocated for UL or DL are configured statically or indicated dynamically, and the center frequencies for TDD UL (as in TDD UL BWP or generally UL resources used in a certain process) and TDD DL (as in TDD DL BWP or generally DL resources used in a certain process) are aligned. For the FDD mode, one part of the paired spectrum is used for UL all the times and the other part is used for DL all the times. A transmission time interval (TTI) generally corresponds to a subframe (in LTE) or a slot (in NR). Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., long term evolution (LTE), LTE advanced (LTE-A), 5G, 5G LTE, 5G NR, future 5G NR releases, 6G, High Speed Packet Access (HSPA), Wi-Fi 802.na / b / g / n / ac, etc. While it is understood that communication systems may employ multiple access nodes (or base stations) capable of communicating with a number of UEs, only one access node, and two UEs are illustrated in FIG. 1A for simplicity.

[0094] A way to increase the network resources is to utilize more usable spectrum resources, which include not only the licensed spectrum resources of the same type as the macro, but also the licensed spectrum resources of a different type as the macro (e.g., the macro is a FDD cell but a small cell may use both FDD and TDD carriers), as well as unlicensed spectrum resources and shared-licensed spectrums. Some of the spectrum resources lie in high-frequency’ bands, such as 6GHz to 60GHz, 70GHz, and even up to 300GHz (sub-TeraHz). The unlicensed spectrums may be used by generally any user, subject to regulatory requirements. The shared-licensed spectrums are also not exclusive for an operator to use. Traditionally, the unlicensed spectrums are not used by cellular networks because it is generally difficult to ensure quality of service (QoS) requirements. Operating on the unlicensed spectrums mainly includes wireless local area networks (WLAN), e.g., the Wi-Fi networks. Due to the fact that the licensed spectrum is generally scarce and expensive, utilizing the unlicensed spectrum by the cellular operator may beconsidered. On high-frequency bands and unlicensed / shared-licensed bands, typically TDD is used, and hence the channel reciprocity can be exploited for the communications.

[0095] In a practical deployment, a gNB may control one or more cells. Multiple remote radio units may be connected to the same baseband unit of the gNB by fiber cable, and the latency between baseband unit and remote radio unit is quite small. Therefore, the same baseband unit can process the coordinated transmission / reception of multiple cells. For example, the gNB may coordinate the transmissions of multiple cells to a UE, which is called coordinated multiple point (CoMP) or multi-TRP (mTRP, M-TRP) transmission. The gNB may also coordinate the reception of multiple cells from a UE, which is called CoMP / M-TRP reception. In this case, the backhaul link between these cells with the same gNB is a fast backhaul, and the scheduling of data transmitted in different cells for the UE can be coordinated in the same gNB. The backhaul connections may also be ones with longer latency and lower transmission rates.

[0096] FIG. 1B illustrates the use of carrier aggregation (CA), which is another deployment strategy. As shown in FIG. 1B, system 150 is a wireless network configured with carrier aggregation (CA) where communications controller 160 communicates to a wireless device 165 using wireless link 170 (solid line) and to wireless device 166 using wireless link 172 (dashed line) and using wireless link 170, respectively. In some example deployments, for wireless device 166, wireless link 170 can be called a primary component carrier (PCC) while wireless link 172 can be called a secondary component carrier (SCC). In some carrier aggregation deployments, the PCC can carry control signaling and data between a UE device and a communications controller while the SCC can mainly carry data traffic. In the 3GPP specifications, a component carrier is called a cell. When multiple cells are controlled by a same eNB, cross scheduling of multiple cells can be implemented because there can be a single scheduler in the same eNB to schedule the multiple cells. With CA, one eNB may operate and control several component carriers forming primary cell (PCell) and secondary cell (SCell).

[0097] Physical layer channels and signals include PSS / SSS, PBCH, and its associated demodulation reference signal (DMRS) (see e.g., FIG. 2A, in which the SS bursts are multiplexed with PBCH around the SS bursts), PDSCH and its associated DMRS and phase tracking reference signal (PT-RS), PDCCH and its associated DMRS (see e.g., FIG. 2B for some of these signals / channels which are multiplexed for more than one UE), and CSI-RS which further include those used, for CSI acquisition, for beam management, and for tracking (see FIG. 2C for some examples of non-zero power (NZP) CSI-RS used for channel estimation, interference measurement, and so on, which aremultiplexed with PDSCH and for one or more UEs). The CSI-RS for tracking is also called TRS.

[0098] The UE receives timing advance (TA) commands associated with the configured TA group (TAG). These commands help the UE adjust its uplink transmission timing to synchronize with the network, ensuring that uplink transmissions from multiple UEs arrive at the base station at about the same time in a transmission time interval (TTI). Likewise, the UE receives DL reference signals (RS) or synchronization signal (SS) blocks (SSBs) to acquire and maintain the DL synchronization, such as via maintaining a DL timing tracking loop, based on which the UE places the start of its FFT window inside the cyclic prefix (CP) for its DL reception. In addition, both UL and DL signals / channels are to be associated with some other signals for deriving the signal / channel properties, such as delay spread, Doppler shift, etc.[00991 In wireless communications operations, tracking functionalities performed by a UE may include fine time tracking, fine frequency tracking, delay spread estimation, and Doppler spread estimation.

[0100] In fine time tracking, a UE may detect the first arriving path, and based thereon, the UE may generally optimally place its Fast Fourier transform (FFT) window to maximize a data signal to noise plus inter-symbol interference ratio. In a continuous operation, a FFT window- position may drift due to UE mobility and a residual oscillator error between a transmitter and a receiver. The UE may adjust its FFT window position based on a detected change of path arriving (or arrival) time.

[0101] In fine frequency tracking, a UE may detect a frequency offset between a transmitter and a receiver, and adjust its oscillator accordingly. A residual frequency error may be estimated and compensated in the demodulation of data symbols. The residual frequency error compensation may be very critical, especially in the case of high signal-to-noise ratio (SNR) and high code rate data transmissions. Uncompensated frequency error may cause phase errors on modulated data symbols and result in decoding performance degradation. Because temperature change affects output precision of an oscillator and Doppler shift caused by UE movement, a UE may periodically track the frequency offset and apply corresponding adjustment and compensation.

[0102] Delay spread determines how dispersive a wireless multi-path channel that a UE experiences is. The longer the delay spread, the more frequency selective the channel is. To generally maximize processing gains along the frequency domain in channel estimation based on received pilot signals, the UE may apply linear filtering with a length as long as possible if within the coherent bandwidth of the channel. Coherent bandwidthis inversely proportion to channel selectiveness. Thus, delay spread estimation plays an important role in forming channel estimation filter coefficients and length, hence affecting the performance of channel estimation and data demodulation.

[0103] Doppler spread is usually proportional to UE movement speeds and multipath spatial distribution. Larger Doppler spread corresponds to a faster changing wireless multi-path fading channel. Channel estimation usually applies filtering in the time domain with longer filter length to suppress noise plus interference if within the channel coherent time constraint. Doppler spread estimation is thus another factor along the time domain affecting UE channel estimation performance.

[0104] The quasi co-location (QCL) types corresponding to each DL RS (more specifically, the port(s) or antenna port(s) of the DL RS) are given by the higher layer parameter qcl-Type in QCL-Info and may take one of the following values: 1) 'QCL- TypeA': {Doppler shift, Doppler spread, average delay, delay spread}; 2) ’QCL-TypeB': {Doppler shift, Doppler spread}; 3) 'QCL-TypeC': {Doppler shift, average delay}; and 4) 'QCL-TypeD': {Spatial Rx parameter}. The QCL types may be configured / indicated in transmission configuration indication (TCI) states for a RS. The QCL assumptions are mainly used for DL RS, but can be generalized for UL RS if the association via pathloss RS and spatial relation are specified. The QCL assumption may be specified as: {RS1: QCL Type C to RS2}, {RS1: QCL Type C to RS2 and QCL Type D to RS3}. Then, RS1 (destination RS) derives the properties specified according to the QCL types from the associated (i.e., source) RSs (e.g., RS2). Note that the source RS may be a SSB. Note also that the source RS and destination RS may be on the same carrier or different carriers (i.e., cross-carrier QCL).

[0105] FIG. 3A is a diagram 300 showing QCL assumptions among NR reference signals when wide beams are used for communications. For example, a TRS, a SS block or a broadcast DMRS may be transmitted using a wide beam. FIG. 3A shows QCL configurations among a SS block 302, a DMRS 304, a CSI-RS 306, a TRS 308, a CSI-RS 310 and a DMRS 312. The DMRS 304 is for a broadcast channel. That is, the DMRS 304 is a DMRS used for demodulation of a system information block (SIB), radio resource control (RRC) signaling, paging, etc. before a TRS is configured. The CSI-RS 306 is transmitted for beam forming. The CSI-RS 310 is transmitted for channel estimation. The DMRS 312 is used for demodulation of signals transmitted in a unicast channel. An arrow starting from a first reference signal (e.g., the SS block 302) and ending at a second reference signal (e.g., the DMRS 304) indicates that the second reference signal has a QCL relationship with the first reference signal with respect to one or more QCL parameters. The one or more QCL parameters (e.g., an average delay, a Doppler shift, adelay spread, and a spatial RX) are show n on the arrow, indicating that the one or more QCL parameters required by the second reference signal may be derived using the first reference signal.

[0106] As shown, the DMRS 304 is configured to have a QCL relationship with the SS block 302. The average delay, Doppler shift, delay spread, and spatial RX for the DMRS 304 may be derived based on the SS block 302. Similarly, the CSI-RS 306 and the TRS 308 has a QCL relationship with the SS block 302, respectively. An average delay, a Doppler shift, and a coarse spatial RX required by the CSI-RS 306 may be derived based on the SS block 302. An average delay, a Doppler shift, and a spatial RX required by the TRS 308 may be derived from the SS block 302. The CSI-RS 310 has a QCL relationship w ith the CSI-RS 306 and the TRS 308, respectively. The CSI-RS 310 may be received using a spatial RX derived based on the CSI-RS 306, and use an average delay, a Doppler shift, and a delay spread from the TRS 308. The DMRS 312 has a QCL relationship with the TRS 308 and the CSI-RS 310, respectively. The DMRS 312 may be received using a spatial RX derived based on the CSI-RS 310. The DMRS 312 may also be received an average delay, a Doppler shift, a Doppler spread and a delay spread derived based on the TRS 308.

[0107] FIG. 3B is a diagram 350 showing QCL assumptions among NR reference signals when narrow beams are used for communications. FIG. 3B shows QCL configurations among a SS block 352, a DMRS 354, a CSI-RS 356, a TRS 358, a CSI-RS 360 and a DMRS 362. Similar to FIG. 3A, the DMRS 354 is for demodulation of signals in a broadcast channel, e.g., a physical broadcast channel (PBCH), that is transmitted before a TRS is configured. The CSI-RS 356 is transmitted for beam forming. The CSI-RS 360 is transmitted for channel estimation. The DMRS 362 is used for demodulation of signals transmitted in a unicast channel. An arrow starting from a first reference signal and ending at a second reference signal indicates that the second reference signal has a QCL relationship with the first reference signal with respect to one or more QCL parameters. The one or more QCL parameters shown on the arrow indicate that the one or more QCL parameters required by the second reference signal may be derived using the first reference signal. FIG. 3B shows that the reference signals have QCL configurations similar to those illustrated in FIG. 3A, except for TRSs. In FIG. 3B, the TRS 358 has a QCL relationship with the SS block 352 and the CSI-RS 356, respectively. The TRS 358 may be received using a Doppler shift derived based on the SS block 352, and may be received using an average delay and a spatial RX derived based on the CSI- RS 356. Data transmission may employ multiple narrow beams, and multiple narrow TRS beams may be required for tracking. To support both of the scenarios, configurationof TRSs and their QCL assumptions or association should be flexible. In addition to the QCL relation between DL signals and channels, the dependent relationship between UL signals and channels, between UL signals and channels and DL signals and channels, can also be viewed generalized types of QCL, such as how PUSCH / PUCCH depends on their DMRS, how PUSCH MIMO transmissions and / or beams depend on SRS, how PUSCH / PUCCH / SRS / PRACH depend on DL SSB and / or CSI-RS as their pathloss RS and beam reference, etc. In general, all these dependency relationships may be configured / released for UE, or activated / deactivated, or indicated for UE, via TCI state of a signal / channel, in which one or more signals are indicated as the dependency source, and the dependency relationship is also included in the TCI state, so that the UE can derive the necessary properties of signal / channel from the dependency source.

[0108] The SSB consists of primary (PSS) and secondary CSSS) synchronization signals each occupying 1 symbol and 127 subcarriers, and the PBCH spanning across 3 OFDM symbols and 240 subcarriers, but on one symbol leavi ng an unused part in the middle for SSS, as shown in FIG. 3C. For the 3 MHz channel bandwidth, the PBCH is further equally punctured from both edges to span 144 subcarriers. The possible time locations of SSBs w ithin a half-frame are determined by subcarrier spacing, and the periodicity of the half-frames where SSBs are transmitted is configured by the network. During a half-frame, different SSBs may be transmitted in different spatial directions (i.e., using different beams, spanning the coverage area of a cell).

[0109] When an SSB is associated with a remaining minimum system information (RMSI) signaling (which is included in SIB1), the SSB is referred to as a cell-defining SSB (CD-SSB). A primary’ cell (PCell) is associated to a CD-SSB located on the synchronization raster. When an SSB is not associated w ith an RMSI, the SSB is referred to as a non-cell defining SSB (NCD-SSB), which can be used to perform radio link monitor (RLM), beam failure detection (BFD), and radio resource management (RRM) measurements and measurements for random access (RA) resource selection inside the active DL BWP when the active BWP does not contain the CD-SSB.

[0110] The PBCH carries master information block (MIB) information, which provides the UE with parameters (e.g., CORESET#o configuration) for monitoring of PDCCH for scheduling PDSCH that carries the system information block 1 (SIB1). PBCH may also indicate that there is no associated SIBi (via ssb-SubcarrierOffset field), in which case the UE may be pointed to another frequency from w here to search for an SSB that is associated with a SIBi as well as a frequency range where the UE may assume no SSB associated with SIBi is present. In addition, the MIB carries cellBarred data field, which is used by UEs to decide whether to select this cell or reselect another cell.

[0111] Upon receiving SIB1, a UE obtains some other system information (such as freqiiencijBcmdList, tracking AreaCode, trackingAreaList, servingCellConfigCommon, etc.). Other information like cellBarredNES indicates that cell is allowed for UE supporting network energy saving (NES) cell discontinuous transmission (DTX) / discontinuous reception (DRX). ServingCellConfigCommon carries information about the physical Cell ID, downlink configuration common, uplink configuration common, SSB position in a burst, SSB periodicity, etc.).

[0112] SIBt may also include si-Scheduling Info containing si-RequestConfig, which may be used to initiate the random access (RA) procedure on normal uplink in accordance with technical specification (TS) 38.321 using the PRACH preamble(s) and PRACH resource(s) in si-RequestConfig corresponding to the SI message(s) that the UE requires to operate within the cell, and for which si-BroadcastStatus is set to notBroadcasting. Thus a UE may request the system information corresponding to SIBx, where x=2,3,..,t9.

[0113] The gNB may provide the requested SI corresponding to SIB2-SIB19 in multiple ways depending on the UE RRC state.

[0114] For a UE in the RRC CONNECTED state, gNB may provide SI using DCI Format i_o with a cyclic redundancy check (CRC) scrambled with SI-RNTI (identification of broadcast and system information in the downlink). This PDCCH message contains the field system information indicator that indicates whether the system message carried by PDSCH and signaled by this DCI corresponds to SIBt or other SIBx. The DCI t_o scrambled with SI-RNTI also indicates the time, frequency, MCS for the PDSCH that carries SIB information. In addition, it has at least 15 reserved bits.

[0115] For UEs in the RRC INACTIVE or IDLE state, the gNB may provide information via paging. A Short Message (8 bits) may be carried in DCI Format 1_O with the CRC scrambled by P-RNTI (identification of paging and system information change notification in the downlink). Repetitions of SI change indication may occur within preceding modification period or within preceding extended DRD (eDRX) acquisition period. SI change indication is not applicable for SI messages containing posSIBs.

[0116] Cell defining SSB (an SSB with an RMSI associated information) provides or is used for cell (re-)selection and initial access w ith synchronization in time and frequency, frame timing, PCI, SFN, SCS, initial BWP, CORESET# 0 information, SIBt related information, cell barring status, PRACH occasions, downlink CSI energy per resource element (EPRE) and RRM measurements (including signal strength, QCL related information).

[0117] PSS together with SSS provides cell ID, and symbol synchronization. PBCH via MIB’s associated DMRS provides the least significant bits (LSB) of the SSB index (via DMRS sequence and respectively PBCH payload). The SSB index is used for RRM, CSI- RS measurements to assess link quality, and for the link recovery procedures.

[0118] In the case when SSB is not associated with an RMSI, the PBCH indicates that there is no associated SIBi, in which case the UE may be pointed to another frequency from where to search for an SSB that is associated with a SIBi as well as a frequency range where the UE may assume no SSB associated with SIBi is present.

[0119] As specified in TS 38.213, Clause 4.1, for a half frame with SS / PBCH blocks, the first symbol indexes for candidate SS / PBCH blocks are determined according to the SCS of SS / PBCH blocks, where index 0 corresponds to the first symbol of the first slot in a half-frame.

[0120] For instance, for 15 kHz SCS there are 4 SSB transmissions in a half-frame for carrier frequencies smaller than or equal to 3 GHz (symbol indexes of {2,8} + 14 • n, n = 0,1), and 8 SSB transmissions (n = 0,1, 2, 3) for carrier frequencies larger than 3GHz, as shown in FIG. 3D.

[0121] For the initial cell selection, a UE may assume that half frames with SS / PBCH blocks occur with a periodicity of 2 frames. Thus, the SSB burst is confined in a 5 ms window^ with a typical periodicity of 20ms, as shown in Error! Reference source not found.E, w hich can be increased up to 160 ms.

[0122] A UE can be provided a periodicity of the half frames for reception of the SS / PBCH blocks for the serving cell per serving cell by ssb-periodicityServingCell as a part of the information element (IE) servingCellConfigCommon. The IE contains parameters which a UE would typically acquire from SSB, MIB, or SIBs when accessing the cell from RRC IDLE state.[01231 System information (SI) is the information delivered to the UE and for the UE to operate. SI can be delivered via broadcast and unicast, and it can be divided into three types of information: MIB, SIBi and Other SI.

[0124] Master information block (MIB) contains basic cell configuration and information used to acquire SIBi. In order to enable the UE to monitor for the PDCCH scheduling PDSCH carrying SIBi, MIB provides the configuration {pdcch-ConfigSIBi) and the numerology of the broadcast {subCarrier SpacingCommon}. Search space defining the time domain for PDCCH monitoring is provided by pdcch-ConfigSIBi. The search space configuration for PDCCH monitoring occasions for SIBi schedulingprovided by MIB is called Typeo-PDCCH common search space (CSS), the CORESET determining the physical resources of the PDCCH scheduling SIB1 is called Typeo- PDCCH CORESET.

[0125] System information block 1 (SIB1) contains information about other SI available in the cell (RMSI), information used by the UE to decide whether it may access the cell, and information used to perform mobility procedures in the RRC IDLE mode (cell physical layer configuration, including random access related configuration as well as indication of the transmitted SS / PBCH blocks (SSB)).

[0126] There are additional SIBs (from S1B2 onwards) can be delivered through broadcast or “on-demand” (OD) manner. The procedure “on-demand” triggers the network to initiate the broadcast of requested system information messages. The UE is configured with an SI window, where the UE can monitor the PDCCH scheduling the SI message. For each entiy of the SI message list schedutinglnfoLisf), there is a time window duration (si-WindowLength) that occurs with a configured periodicity (sz- Periodicity). Whether the additional SIBs are delivered through broadcast or “on- demand” is signaled in SIBt.

[0127] Random access preambles can be transmitted in the time resources obtained from Tables 6.3-3.2-2 to 6.3.3.2-4 of TS 38.211 and depends on frequency range 1 (FR1) or frequency range 2 (FR2) and the spectrum type. The configuration index in these tables is given by the higher layer parameter prach-Configurationtiidex, or by msgA- PRACH -Configurationindex if configured.

[0128] PRACH slots have periodicities from 10 ms up to 160 ms, Table 6.3.3.2-3 (FR1) and Table 6.3-3.2-4 (FR2) ofTS 38.211.

[0129] The PRACH slots are in the index frame given by the formula nfmod x = y, where x is the configuration period {1,2,4,8,16}. The PRACH slots are in a subframe (indicated by the subframe number) while the number of slots is indicated by the number of PRACH slots within a subframe (none, one or two). For instance, in Table 6-3-3.2-3 of TS 38.211, if PRACH configuration 76 is selected, the period x=2, i.e. 20 ms, thus in the odd frames, one PRACH slot will be in each of the subframes 2, 3, 4, 7, 8, 9.

[0130] In the above tables for FR2, the column of the subframe number is replaced with the column of slot number, where a slot duration corresponds to 60 kHz SCS.

[0131] The UE can monitor the paging occasions (POs) as described in clause 7.1 of TS 38.304 to receive the SI change notifications in RRC_IDLE and RRC_INACTIVE states. The network notifies SI changes using a Short Message as specified in TS 38.331.Upon receiving this Short Message about SI changes, the UE can acquire or re-acquire the concerned SI as specified in TS 38.331.

[0132] The paging procedure is used to transmit information to a UE in RRC_IDLE or RRC_INACTIVE state. The UE may use DRX in RRC_IDLE and RRC_INACTIVE states to reduce power consumption. The UE can monitor one PO per DRX cycle.

[0133] The network initiates the paging procedure by transmitting the paging message at the UE's paging occasion as specified in TS 38.304. The network may address multiple UEs within a paging message by including one PagingRecord for each UE. The network may also include one or multiple temporary mobile group identiti(es) (TMGl(s)) in the paging message to page UEs for specific multicast and broadcast services (MBS) multicast session(s).

[0134] For each SSB, there are several paging occasions (nrofPDCCH- MomtoidngOccasionPerSSB-InPO).

[0135] The number of PDCCH monitoring occasions corresponding to an SSB w ithin a PO is specified in TS 38.304, clause 7.1.

[0136] The maximum number of POs per paging frame is 4. One paging frame (PF) is one radio frame and may contain one or multiple POs or the starting point of a PO.

[0137] The PF and PO for paging are determined by the following formulae.

[0138] SFN for the PF is determined by the formula below.(SFN + PF_offset) mod T = (T div N)*(UE_ID mod N)

[0139] Index (i_s), indicating the index of the PO, is determined by the formula below. i_s = floor (UE_ID / N) mod Ns

[0140] T is the DRX cycle of the UE. If UE does not operate in the DRX (eDRX) mode, T is determined by the shortest of the UE specific DRX value (s), if configured by the RRC and / or upper layers, and a default DRX value broadcast in SI.

[0141] N is the number of total paging frames in T.

[0142] Ns is the number of paging occasions for a PF.

[0143] PF_offset is the offset used for PF determination.

[0144] For UE_ID, if the UE operates in eDRX as specified in clause 7.4, UE_ID is 5G-S-TMSI mod 4096; otherwise, the UE_ID is 5G-S-TMSI mod 1024.

[0145] Parameters Ns, nAndPagingFrameOffset, nrofPDCCH- MonitoringOccasionPerSSB-InPO, and the length of default DRX Cycle are signaled in SIBi. The values of N and PF_offset are derived from the parameter nAndPagingFrameOffset as defined in TS 38.331. The parameter firstPDCCH- MonitoringOccasionOfPO is signaled in SIBi for paging in the BWP configured by initialDownlinkBWP. For paging in a DL BWP other than the BWP configured by initialDownlinkBWP, the parameter first-PDCCH-MonitoringOccasionOfPO is signaled in the corresponding BWP configuration.

[0146] The values for paging cycle period (T) are defined in TS 38.331.PagingCycle ::= ENUMERATED {rf32, rf64, rfl28, rf256}

[0147] In Rel-17 more values were added.ExtendedPagingCycle-riy ::= ENUMERATED {rf256, rf5i2, rfiO24, sparei}

[0148] These values allow extending the period up to 1024 frames =10.2403 duration.

[0149] In wireless systems, energy efficiency can be a desirable performance indicator and hence a desirable design objective. One approach to higher energy efficiency is to minimize always-on, broadcast transmissions of signals and channels. However, the always-on transmissions may not be able to be completely eliminated, as they may be used by the UE to acquire time / frequency synchronization, tracking, MIB and SIBs, etc. Removing or reducing always-on transmissions may lead to higher complexity and / or higher latency in the initial access procedure, and so on. Some implementations are provided to achieve high energy efficiency w hile keeping the complexity and latency low7. While these implementations are provided for the cellular case (the gNB to / from UE communication) as illustrative examples, they can be extended as well to sidelink communication for reducing always on transmissions of sidelink PSS (S-PSS), sidelink SSS (S-SSS), and sidelink PBSCH (S-PBSCH).

[0150] In some implementations, the network device (or network entity) transmits always-on transmission, which broadcasts a new-format SSB, with periodicity pi. The SSB periodicity can be similar to, or even shorter than, the current SSB periodicity in 5G NR, so that it can facilitate UE search of the SSB and lower initial synchronization and SI acquisition latency . There is a list of possible pi values standardized w ith a default value such as 5 ms or 20 ms. To reduce energy consumption, signal / signaling overhead, and network / UE processing complexity, the data channel included in the SSB, which may be called minimum MIB (MMIB) carried by the PBCH, is minimized and carries as fewinformation bits as possible. In addition, periodic transmissions other than the SSB can be significantly reduced, becoming trigger based (i.e., on-demand (OD) transmissions), and / or with extended periodicities, such as transmitted w ith periodicity of t‘:fpi, where t > 1.

[0151] In an implementation, one SSB transmission includes a synchronization signal (SS) called primary synchronization signal (PSS) and an MMIB. The PSS may occupy one OFDM symbol and be repeated within one SSB transmission. That is, in one SSB transmission, there may be two or more PSS symbols; the two or more PSS symbols transmitted in one SSB transmission may be called a PSS burst. That is, n SSB transmissions may include n PSS bursts, and each PSS burst includes multiple PSS symbols. An implementation can be that a PSS burst has only 2 PSS symbols, and based on the detection of which and the information carried in MMIB, the UE can fully identify the timing / relative position of the PSS burst in the SSB cycles. On the other hand, the benefit of multiple PSS symbols (e.g., m PSS symbols) with m-1 PBCH / MMIB symbols in between could be that UE can acquire the SSB with low er latency as the UE may accumulate several PSS / MMIB transmissions in one burst. One OFDM symbol lies between one PSS symbol and the next PSS symbol wdthin a PSS burst. The PSS sequence is one of a number of sequences predefined in the standards. The SSB is located on a certain synchronization raster. When a UE performs a search and correlation of the PSS, it can detect at least two PSS instances in a burst separated by only one symbol in between. Based on the time durations of the PSS instances and the gap in between, the UE can estimate the OFDM symbol duration. The symbol in between the PSS symbols (and possibly some symbols around them) carry MMIB. The UE searches for the DMRS associated with MMIB among several possible DMRS configurations predefined in standards. A benefit of using only the PSS in the SSB could be that the PSS is usually designed to have a very’ small number of sequences (ty pically only’ 3), and hence it can be short and occupy less resources, and the search / detection of the sequence is of low complexity . In some other embodiments, a secondary sy nchronization signal (SSS) or a tertiary synchronization signal (TSS) is also transmitted in an SSB. The secondary and tertiary synchronization signals may be used by a UE for finer synchronization, or for identification of a cell or a validity area, or for carrying additional configuration information such as the type of the PBCH, etc.

[0152] The UE may then attempt to decode the PBCH, remove CRC, descramble, and obtain the payload of the PBCH or the MMIB. In some embodiments, the MMIB carries at least the scheduling information for another configuration information transmission in the DL direction. For example, the MMIB may7indicate the resource allocationinformation for a random access (RA) procedure configuration transmission. In some implementations, the MMIB does not indicate directly how the RA is configured, but indicates the resources for transmitting the RA configuration. For example, MMIB may include a bit field called “RA configuration transmission resource information”. This field may indicate a time / frequency-domain offset. This offset may be relative to the time / frequency-domain position of a reference point determined based on the SSB transmission, e.g., the reference point being the first PSS symbol, and the starting subcarrier (SC) of the SSB, or equivalently a later SS symbol and a different SC. Based on the position of the reference point and the time / frequency-domain offset in the field “RA configuration transmission resource information,” the UE can find the RA configuration transmission resource. In some embodiments, the bitfield does not directly indicate the time / frequency-domain offset. Instead, a set of n time / frequency-domain offsets predefined in the standards can be introduced, and each offset is associated with a unique index from o to n-1 with bit width log2(ceil(n)). In an implementation, all parameters in the field “RA configuration transmission resource information” can be associated with a unique index from o to N-t with bit width log2(ceil(N)).Correspondingly in the standards, a list of N configurations or a table of N rows can be defined, each associated with a unique index and including a combination of RA configuration transmission parameters. This approach to indicate a parameter or a set of parameters can be applied to other implementations elsewhere, such as the jointly coded WUS transmission resource and RA configuration transmission resource.

[0153] In some implementations, the RA configuration transmission resource is recurring with the same periodicity as the SSB. However, in some embodiments, on some of the RA configuration transmission resources following some SSB transmissions, the RA configuration transmission is not transmitted on the resources every’ time, even though the resources are reserved. The RA configuration transmission can be performed with longer periodicity such as t*pi and / or on-demand per WUS, as described below. In a different implementation, there is a mapping betw een the SSB transmissions and the transmissions of RA configuration. Such mapping can be for instance specified by a bitmap and repeated periodically. The bitmap may be specified as a priori or preconfigured, and may be indicated in the SSB transmission.

[0154] In one implementation, the periodicity multiplier t of the RA configuration transmission can be explicitly provided in the MMIB. Alternatively, MMIB conveys information about the number of SSB transmissions before the RA configuration transmission on the resource reserved for the RA configuration is sent. For example, an “RA indicator”, or “RA configuration transmission indicator” can be carried by the MMIBin each SSB transmission. For a sequence of consecutive SSB transmissions, the RA indicator sequence may be {o, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, ... }. Generally, the RA indicator decrements by 1 for each transmission, and resets to 7 (or the maximum allowed) when reaching 0. When the RA indicator indicates o for a SSB transmission, the RA configuration will be transmitted after the SSB transmission that indicates o and before the next SSB transmission according to the indicator time / frequency-domain offset. A UE receiving the RA indicator would know how’ long it will w ait until receiving the RA configuration, based on the periodicity of the SSB transmission (determined via UE scanning in the time domain, or via a field in the MMIB) and the value of the RA indicator. It is possible that a UE fails to receive a SSB transmission, but the decrementing / resetting of the RA indicator is the network behavior and hence not affected by whether a UE successfully receives a SSB transmission or not. A UE may obtain the periodicity of the SSB based on the SSB transmissions it has received. For example, if the UE receives RA indicator 5 followed by 4, the UE knows it has received two consecutive SSB transmissions, and the time difference is the periodicity if the duration is in accordance with a standardized pi value. If the UE receives RA indicator 5 followed by 3, the UE may reason that one SSB transmission is not received in between, and it may also find the SSB periodicity based on the list of standardized pt values; however, in some cases, the UE may need to receive more SSB transmissions to obtain the SSB periodicity information.

[0155] In some embodiments, to provide the network with more flexibility, the network may alter the value of the RA indicator to send RA configuration sooner. That is, the mechanism supports not only periodic transmission of the RA configuration, but also aperiodic ones. For example, right before RA indicator 6 is sent, the network determines a need for an extra aperiodic RA configuration transmission after RA indicator 5. Then, the sequence temporarily becomes {o, 7, 1, 0, 4, 3, 2, 1, 0}, and an extra, aperiodic RA configuration is sent when the RA indicator is o (the one before the 4 in the sequence {o, 7, 1, 0, 4, 3, 2, 1, 0}) according to the indicated offset in the SSB. The UE monitoring the RA indicator can know the aperiodic transmission of RA configuration and hence can receive the configuration. The aperiodic transmission of the RA configuration is on the reserved RA configuration transmission resources as indicated by the MMIB, immediately following the SSB carrying the RA indicator 0. After that, the sequence can resume its general pattern of {0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, ... }. The network may also decide to use a more complicated pattern, such as {0, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, ... }, such as the RA configuration transmission is non-uniform in time. In an embodiment, the RA indicator is one bit, withone value indicating the transmission of the RA configuration on the allocated resource and the other value indicating not transmitting the RA configuration. This can reduce the overhead and complexity associated with more than two RA indicator values, but may not be suitable for periodic broadcasting of the RA configuration. A 2 or 3 (or even 4 in some cases) bit RA indicator may be more useful for energy saving in some systems.

[0156] However, generally it is allowable for the network to add extra RA configuration transmission, but undesirable for the network to cancel a pre-scheduled one, that is, sequence such as {o, 7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, ... } should be avoided. This is because UE may not be monitoring the RA indicator in all SSB transmissions. The UE may receive RA indicator 5 and expect that the RA configuration will be sent after 5 SSB transmissions; then the UE may go to sleep without monitoring SSB and wake up after 5 SSB transmissions to receive the RA configuration. If the RA configuration is not received, this may cause some issues for the UE. In a different implementation, the UE is expected to wake up and monitor for the SSB with RA indicator -O, which is transmitted prior to the RA configuration. In other words, there is a validation of the RA configuration transmission via RA indicator value =0. If the indicator =0 is replaced by another value, the UE should not expect that the RA configuration will follow that SSB transmission, and should expect the next RA configuration transmission based on the latest RA indicator value. In other words, the UE can assume that, if the RA indicator is k, the RA configuration will be sent at the k-th SSB transmission (after the current one), and the UE assumption is adopted by both the network and the UE.

[0157] In an implementation, the RA indicator counter cannot decrease faster than k=i at a time, which means that the UE can estimate a minimum duration until the RA configuration is broadcast, thus could schedule a minimum duration for the low energy state. For instance, a UE receives a RA indicator counter of value 4; therefore, the RA indicator cannot reach a value o in less than 4 steps (i.e. the fastest decrement k=i in each step). In a different implementation, the RA indicator counter cannot decrease faster than k units at the time. For instance, if the RA indicator counter has a value of 6, it cannot reach value o in less than 3 decrements when k=2, which would still allow UE to schedule for 3 periods pt duration of a low energy state.

[0158] In an implementation, the RA indicator is carried in a bit field included in the MMIB. However, a potential drawback of this implementation is that the PBCH payload varies in consecutive SSB transmissions, and thus UE cannot combine the received samples for better decoding performance. In an implementation, the RA indicator is conveyed via the channel coding scrambling of the PBCH, similar to how the existing 5GPBCH conveys the 4 LSB of the System Frame Number (SFN) via the channel coding procedure. Then, the PBCH payload (e.g., as the encoded bits) can remain the same and the UE can combine multiple transmissions. The RA indicator may use a few bits in the scrambling (e.g., 2 or 3 bits). 2 bits can correspond to {0, 3, 2, 1, 0, 3, 2, 1, 0, 3, 2, 1, ...}. 3 bits can correspond to {0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, ... }.

[0159] However, with only periodic and aperiodic transmission of the RA configuration determined by the network, it may still lack sufficient flexibility. For example, when a UE reads RA indicator 7, it knows that it has to wait for a while to receive the RA configuration (i.e., after a time duration of 7*pi). If the UE has no traffic for now (or no time-sensitive traffic, or is in energy-saving mode, etc.), it can go to sleep during the waiting and wake up later to receive the RA configuration, without sacrificing any performance. But if the UE has time-sensitive traffic or for any reason, it needs to connect sooner, it is desirable to have a mechanism to trigger the RA configuration transmission sooner. Then, in some implementations, triggered transmission of the RA configuration is provided, based on a (UL) wake-up signal (WUS) procedure. That is, the UE is provided with WUS configuration, and can transmit the WUS to the network. In response to the WUS, the network transmits the RA configuration to the UE. Though the descriptions of periodic, aperiodic, and triggered transmission of the configuration are mainly for RA configuration, additional configuration information can also be included to accompany the transmission of RA configuration, in w hich case it may be called “RA configuration transmission” and other related terminologies can be modified accordingly. Furthermore, the mechanisms can be applied to the transmission of other configuration information, such as remaining MIB (MIB other than MMIB), SIBt, remaining SI, etc., which may or may not be part of the initial access procedure. The WUS procedure is substantially more efficient than a current RA procedure, and hence receiving the WUS configuration can have much low er overhead and latency than receiving the RA configuration. For example, the WUS procedure is to trigger a transmission of non-UE specific configuration information and hence can be a two-step procedure, but the RA procedure usually delivers some UE-specific information in the UL and / or the DL, which may experience higher configuration signaling overhead and latency.

[0160] In some implementations, the MMIB carries configuration information for a UE to perform a wake-up signal (WUS) procedure. In a WUS procedure, the UE first acquires WUS transmission configuration from the network (e.g., gNB), then performs the uplink WUS transmission, and finally receives the RA configuration. There may be a few- bit fields for the WUS configuration, and it is expected to be much smaller than theRA configuration information. In some embodiments, the WUS configuration information is carried by the MMIB.

[0161] One field for the WUS configuration includes a few bits for UE to know the time / frequency-domain resource for the WUS, on which the UE may transmit the WUS. The resource may be indicated via the time / frequency-domain offset relative to a reference point, which could be based on the time / frequency-domain position of the SSB. There can be a few options of time / frequency-domain offsets predefined in standards, and the bit field indicates one of them. The design of the UL WUS resources indication may be similar to the abovementioned DL resource allocation information for the RA configuration transmission, except that this design is for the UL. In one implementation, the WUS transmission resource offset and the WUS response (i.e., including the RA configuration) resource offset use the same reference point. The UL WUS resource indicated by WUS resource offset may be earlier than the DL RA configuration transmission resource in time, and thus, after the UE receives the corresponding SSB, the UE can perform WUS transmission and then expect the RA configuration to be sent during the current SSB period (i.e., immediately after the current SSB transmission) in the next RA configuration transmission, without the need for waiting for the next SSB transmission, which can help reduce latency. Alternatively, if the UL WUS resource is scheduled later than the DL RA configuration transmission time in the current SSB period, the UE sends WUS and expects RA configuration to be sent during the next SSB period (i.e., immediately after the next SSB transmission), which can allow the UE and the network more time to prepare / process the transmission and reception. In this case, the offset for the WUS reply (i.e., including the RA configuration) is considered by the UE relative to the reference point in the next SSB transmission. In an implementation, one field includes information for both the UL time / frequency-domain resource for WUS and the DL time / frequency-domain resource for RA configuration transmission, i.e., the two configurations are jointly coded. In a preferred embodiment, the WUS reply is always transmitted in the resource configured (i.e., reserv ed) for the RA configuration transmission indicated by the MMIB. In an implementation, the MMIB indicates the TDD mode, or indicates a frequency-domain offset for the WUS transmission within a threshold value (e.g., 12 PRBs assuming 15 kHz SCS, or equivalent to 2.5 MHz; 24 PRBs assuming 15 kHz SCS, or equivalent to 5 MHz) so that the UE assumes TDD. The UE can assume the center frequencies of UL and DL bandwidths are aligned. In another implementation, the MMIB indicates the FDD mode, or indicates a frequency-domain offset for WUS transmission larger than a threshold value so that the UE assumes FDD. The UE can assume the SSB and RA configuration are sent in the DL carrier but the WUSis on the UL carrier. In an implementation, the time-domain offset between the SSB transmission and the WUS transmission is sufficiently long to accommodate one or more of the following switching times: UE switching time from DL to UL (for TDD), UE RF retuning for a potential center frequency changing (such as for a BWP switching, for TDD or FDD), network switching time from DL to UL (for TDD), UE processing time for receiving and processing the SSB and preparing the WUS transmission, etc. In an implementation, the (additional) time-domain offset between the WUS transmission and the RA configuration transmission is sufficiently long to accommodate one or more of the following switching times: UE switching time from UL to DL (for TDD), UE RF retuning for a potential center frequency changing (such as for a BWP switching, for TDD or FDD), network sw itching time from DL to UL (for TDD), network processing time for receiving and processing the WUS and preparing the RA transmission, etc.

[0162] In one implementation, in each SSB period, there may be a single offset to indicate either the resource (time and frequency) for the (downlink) RA configuration transmission or for the (uplink) WUS transmission. The SSB may have a 2 bit indication w hether the resource may be used for the UL WUS transmission or for WUS configuration information or will be used for RA configuration information. Thus, the resource may be flexibly used in a time division multiplexing (TDM) manner either for the dow nlink or for the uplink, for instance, using flexible symbols, which can be used both for UL and DL purposes. The purpose of symbol usage can be signaled via sequence combination w hile leaving sufficient time for UE to process the sequence combinations. Given that WUS transmission occupies less resources than the RA configuration transmissions, multiple uplink WUS transmissions may be multiplexed in the same resources, thus minimizing the possibility of collisions. In a different implementation, the WUS information is fixed (a single preamble configuration for a specific type of WUS and specific UL WUS resource allocation), w here the resources for the same UL WUS transmissions are the same for users, thus all the potential UL WUS will be transmitted in the same resources and given that their transmissions happen in the limit of cyclic prefix and inter-carrier spacing they will be received by the gNB as copies of the same transmission, suitable for combining for an increased signal to noise ratio (SNR).

[0163] One field of the WUS configuration indication may include a few bits for the UE to know WUS resource types (e.g., Type 1 of 14 OFDM symbols and 2 subcarriers, Type 2 of 7 OFDM symbols and 2 subcarriers, etc.).

[0164] One field may inform the UE about the WUS preamble configuration (e.g., value o for WUS preamble configuration 0, 1 for WUS preamble configuration 1, etc.). Each WUS preamble configuration may include one or more WUS preamblespreconfigured according to standards. However, generally there is no need to identify the UE during a WUS procedure, so the WUS preambles are different from RACH preambles which are desirable to avoid preamble conflict, there can be one WUS preamble corresponding to a WUS preamble configuration. This can also simplify UE behavior and network monitoring of the WUS preambles. Different WUS preamble configurations may be intended for different purposes (e.g., one may be intended for URLLC UEs, another for loT UEs, another for UEs supporting certain features, etc.) so that the network can identify the types of requests or requirements for the WUS procedure and can respond differently.

[0165] A number of CRC bits can also be included in MMIB, such as 16 bits, 24 bits, etc. When the number of MMIB information bits is small (e.g., much smaller than the legacy MIB), a smaller number of CRC bits may be used, such as 8 bits.[01661 Error! Reference source not found, illustrates some of the above implementations. A down arrow is a network transmission in the DL to UE, and an up arrow is a UE transmission in the UL to the network. The top portion 402 of FIG. 4 shows legends for: 1) SSB, including SS + WUS configuration + RA configuration transmission resource information + RA indicator, 2) WUS monitoring occasions, which are also the potential opportunities for the UE to transmit WUS, 3) WUS transmission, and 4) RA configuration transmission. The RA indicator uses 2 bits in this example, i.e., t = 4, and the sequence generally goes {0, 3, 2, 1, 0, 3, 2, 1, 0, 3, 2, 1, ...}. When the indicator is o, the network (e.g., the base station) sends the RA configuration on the resource indicated in the SSB. These are shown in the “periodic activities” portion 406 of FIG. 4. In addition, “on-demand activities (triggered by WUS)” is also provided. In this example, after RA indicator 3 is sent, UE uses the WUS configuration acquired in the SSB to transmit a WUS. The network monitors for a WUS, and once the network detects the WUS, and in response, it sends a RA configuration. The RA configuration is sent on the RA configuration transmission resource configured in the MMIB, which may also be called a “WUS reply,” thus the RA configuration transmission resource may also be called “WUS reply configuration” or “WUS message 2.” The UE does not have to wait until the next RA indicator 0 to acquire the RA configuration. In an implementation, the RA configuration transmission is similar to the PBCH / MMIB transmission, which can have a few different formats but without PDCCH. This implementation can be suitable for common RA configuration broadcasting in a non-UE-specific way, and it reduces the RA configuration acquisition overhead, complexity, and latency since the UE does not have to perform search space search or blind decoding, but has limited flexibility. In an alternative implementation, the RA configuration transmission is similar to SIB1transmission and different from the PBCH / MMIB transmission (e.g., the RA configuration transmission can have a PDCCH w ith a few different choices in the search space design (temporary search space #o) and CORESET design (temporary CORESET #o)), and the PDCCH points to a PDSCH for earn ing the RA configuration. The bandwidth part carrying the reply and configured with tempo ran search space #0 and temporary CORESET #o can be called a temporary DL BWP, with associated RA-RNTI and TC-RNTI. This implementation may have higher RA configuration acquisition overhead, complexity, and latency, but offers more flexibility in delivering more configuration information.

[0167] Although most of the descriptions of the implementations include both the periodic RA configuration transmission and trigger-based RA configuration transmission, either can be separately utilized. In some implementations, the MMIB indicates the periodic RA configuration transmission, without the WUS configuration. In some other embodiments, the MMIB indicates the WUS procedure (including configurations for WUS transmission and WUS reply configuration), but does not indicate periodic RA configuration transmission.

[0168] For the periodic activities, in some alternative embodiments, WUS monitoring is not needed when the RA indicators indicate o. This is because both the network and the UE know that RA configuration is to be transmitted in this instance, so there is no need to use a WUS to trigger the RA configuration transmission. The UE is not expected to transmit a WUS in such situation. Thus, WUS monitoring and WUS transmission are not enabled for every SSB transmission, and the resources corresponding to the skipped WUS monitoring may be used for other transmissions.

[0169] Other examples are described here. For example, when t = 8, then, the network (NW) (e.g. base station) broadcast SSBs accompanied with indicator sequence {o, 7, 6, 5, 4, 3, 2, 1, o, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, ... }. When the RA indicator is o, the NW sends the RA configuration on the resource as indicated in the SSB (e.g., the SSB includes an offset, and the transmission is according to the offset from the SSB). For example, when t = 8, a UE detects a RA indicator value of 6 in an SSB transmission. The UE knows that it can wait for 6 more transmissions (excluding the current one and including the one sent with the RA configuration) to receive the RA configuration. But the UE may have some time-sensitive needs. Therefore, the UE transmits a UL WUS on the next occasion. The NW receives the WUS and transmits the on-demand RA configuration immediately after that on the next occasion, on the resource according to the offset indicated in SSB. For example, when t = 8, but right before RA indicator 6 is sent, the NW determines a need for an extra aperiodic RA configuration transmissionafter sending RA indicator 5. Then, the sequence temporarily becomes {0, 7, 1, o, 4, 3, 2, 1, o }, and an extra, aperiodic RA configuration is sent according to the offset in SSB. This changes the RA indicator transmission from its simple decrementing / resetting pattern, and this requires corresponding UE behavior so that any monitoring UE understands the change of the RA indicator decrementing pattern and hence triggered RA configuration transmission may occur. This approach can increase the UE complexity, but it provides high flexibility useful to improve energy efficiency and system agility .

[0170] The RA configuration includes all necessary information for a UE to send a PRACH preamble and to receive a response. This could include information, such as a range of sequences, for PRACH preambles, time / frequency-domain resources for the RA occasions, time / frequency-domain resources for the random access response (RAR), etc. More details are described below.[01711 In an implementation illustrated in FIG. 5, the NW responds to an WUS by transmitting the RA configuration, but the response is delayed by one SSB transmission occasion. More UEs may be able to receive the RA configuration since the NW can flag the next SSB transmission with RA indicator 0. The support of the delay reply can be either standardized or configured via the MMIB so that the UE would know when to expect the reply.

[0172] In an implementation illustrated in FIG. 6, the NW responds to an WUS by transmitting the RA configuration, and the response is transmitted on more than one SSB consecutive transmission occasions. That is, the triggering UE may be able to receive and decode the RA configuration during the current SSB transmission occasion and may be able to combine the RA configuration transmission with the next for better performance. In addition, more UEs may be able to receive the RA configuration in the next occasion since the network can flag the next SSB transmission with RA indicator 0. Some UEs with faster responding capability may receive the first SSB transmission and be able to proceed to a next operation sooner, whereas UEs without such capability may receive the later one with higher latency. The support of the multiple replies (e.g., m replies) can be either standardized or configured via the MMIB so that UE would know when to expect the replies.

[0173] The flowchart in FIG. 7 illustrates an implementation of supporting periodic / aperiodic / triggered transmission of a channel, such as a channel cariying the RA configuration from the network perspective. As shown in the example in FIG. 7, at the operation 702, the NW (e.g., base station) sets the RA indicator value based on t (where range of the RA indicator is from 0 to t-i). The NW also sets the decrement step value k(default of k is 1). At the operation 704, the NW transmits at least one and any combination of the synchronization sequence, the WUS configuration, the RA configuration transmission information (e.g., RA configuration transmission resource), and the RA indicator. At the operation 706, the NW determines whether (1) the NW receives a WUS, or (2) the RA indicator is o. If neither (1) or (2) is true, at the operation 708, the NW decreases the RA indicator by k (or sets the RA indicator to another value between 0 andt-t), and the flow proceeds to the operation 704. If either of (1) or (2) is true, at the operation 710, the NW either decreases the RA indicator by k if (1) is true, or set the RA indicator to t-1 (or any value between 0 and t-1) if (2) is true. At the operation 710, the NW also transmits the RA configuration on the RA configuration transmission resource (indicated by the RA configuration transmission information transmitted at the operation 702), and the flow proceeds to the operation 704.

[0174] The benefits of such design in FIG. 7 include netw ork energy saving(compared to broadcasting the RA configuration with periodicity pt) and flexibility and shortened latency. If the RA indicator reaches value of 0, it may be reset to the maximum value (t-i) or a different value between 0 and t-i. It is expected that during the SSB period where the RA indicator counter reaches value of o, there is no resource allocated for the UL WUS transmission (since it is not necessary for such trigger during this SSB period). If the RA indicator is different than o, but a UL WUS transmission was received before the RA configuration occasion in the same SSB period, the network then transmits a RA configuration in the same period and continue to decrement the RA indicator counter. In other w ords, the reception of the UL WUS will not cause a reset of the RA indicator counter after the immediate transmission of RA configuration.

[0175] In some implementations, the network configures and transmits more than one set of periodic SSBs on the same or different synchronization rasters, each one associated with a different periodicity and some other parameters (such as a different time offset to each raster transmission). For example, one set may have 1 ms periodicity, w-hich is intended for UEs with highly time-sensitive traffic demand. For another example, one set may have 160 ms periodicity and no WUS configuration, which is intended for UEs with time-insensitive traffic demand. A UE may determine the type or purpose of a set of SSBs based on the periodicity of the SSB, whether the WUS configuration in the MMIB allows for WUS transmission, the bitwidth of the RA indicator field, and / or a field indicating the type of the SSB. For example, if the WUS is not allow ed or configured, the SSB may be used for traffic without stringent latency requirements. An example of 2 sets of SSBs wdth different periodicities is shown in FIG. 8. To reduce UE searching in the frequency-domain and to reduce UE energyconsumption, multiple sets of SSBs may be transmitted on one or more rasters in a narrow bandwidth resource, called “synchronization bandwidth resource,” which maybe always on in time but narrow in frequency-domain, on which a single raster indicates a set of fixed (predetermined) frequency locations. A UE may search for a SSB in a raster, i.e. in a set of selected locations of the potential frequency allocations.

[0176] In some implementations, the SSB includes two or more symbols for the PSS, but no SSS. Thus, the SSB does not identify a cell and does not convey a cell ID, or does not provide sufficient information to convey a full cell ID. In a tightly synchronous and centralized network, this design can be useful. For example, multiple sectors and TRPs can form a single-frequency network (SFN) for the SSB transmission, eliminating pilot pollution and interference on the SSB. The combined single-frequency network transmission can be quite strong and cover an area without any coverage holes even if the SSB transmission on some sectors and TRPs are turned off, leading to higher energy savings for the network. A single-frequency network SSB transmission can thus form a PSS validity area 900 as showoi in Error! Reference source not found., in which at least some of the steps and signals of the connection / camping / mobility procedures can involve no (full) cell ID, w hich may reduce the procedural / signaling overhead and complexity. Other than the initial access, generally the network can assign UE-specific or UE-group-specific resources to communicate with the UE. The UE transmits UL signal(s) with a power level based on the RSRP measurements of the (SFN) PSS transmission, potentially with some power backoff (so that the initial UL transmission would not be of too high power, causing high interference) or power ramping (as some initial UL transmission may not be detectable by the network) configured or specified via standard specifications, but the subsequent UL transmission may be configured with UE-specific or UE-group-specific parameters / resources (such as Po, alpha (a), DL RS for pathloss estimate, and time advance) so that the transmission can be better targeted to a specific TRP, rather than to the network entities in the PSS validity area in general.

[0177] In some implementations, the SSB includes two or more symbols for the PSS without the SSS, as well as one or more PBCH transmissions carrying identical payload, as illustrated in FIG. 10. An example is shown below. The UE can easily identify the PSS 1002 since they appear multiple times in a few symbol durations. And the UE can combine the contents between consecutive PSS symbols to decode MMIB 1004, rather than waiting for the next SSBs to do the combining, w hich leads to higher latency. The multiple PBCH in one SSB transmission may be identically scrambled and coded, so that the UE can simply combine them. Alternatively, they7may be associated with different redundancy7versions with knowoi redundancy version configuration information, so thatthe UE can perform soft combining. In one embodiment, the MMIB between two closest PSS symbols occupies one symbol, i.e., the same duration as a PSS symbol, which simplifies the UE processing in the time domain. In one embodiment, the MMIB occupies the same subcarriers as the PSS, which simplifies the UE processing in the frequency domain. However, if more resources are needed to carry the MMIB, several solution embodiments are possible. One solution embodiment is to specify more than one symbols for MMIB in the time domain (e.g., 2 symbols). Then, the UE needs to correctly identify the symbol boundaries based on the PSS symbols and the gap in between. Another embodiment is to allow more frequency-domain subcarriers for the MMIB so that the MMIB can surround or partially surround the later PSS symbol (similar to 5G PBCH which surrounds the SSS).

[0178] In some implementations, the SSB includes symbols for PSS and SSS, which is similar to the 5G NR design. In an implementation, a mixture of PSS-only SSB and PSS+SSS based SSB are transmitted, as showoi in FIG. 11. In this example, the structure and location of the legacy-structured SSB are exactly as 5G NR and UE can access the SSB for initial access. However, since this SSB has a PSS symbol at its start, a new SSB with only PSS symbols can be provided before it, with the MMIB (to be more precise, it should be called a new7PBCH w hich is the physical channel carrying the MMIB, but we still use MMIB in the figure to differentiate with the legacy-type PBCH cariying legacytype MIB) between the PSS sy mbols. The two SSBs share one PSS symbol. In addition, in this PSS validity area, multiple legacy-structured SSBs can be provided in a TDMed fashion, with each SSB including its specific SSS and time offset. UE may choose to access the network associated with the PSS validity' area without a (full) cell ID involved, or a particular cell with a cell ID based on the PSS and SSS combination. In an embodiment, the bandwidth and frequency-domain location of the MMIB in the new' SSB are the same as those of the new PSS, so that the UE can use the same frequency-domain hardware (e.g., filter) for both and simplify the UE operations. In another embodiment, the ban w idth and frequency-domain location of the MMIB in the new SSB are the same as those of the legacy-type PBCH in the legacy SSB, so that the UE can use the same frequency-domain hardw are (e.g., filter) for processing both the legacy-type SSB and the new' SSB.

[0179] In a different implementation, the network may' send the periodic PSS and SSS and no MMIB, where only selected pairs of the PSS and SSS are allowed. Their combination, used for synchronization in time (symbol level) and frequency (subcarrier level), may also indicate w'hether / when these two sy nchronization signals will be followed by a full SSB transmission. For instance, one combination may' indicate that aSSB transmission may take place Nth symbol after the present transmission. Another combination may indicate that a full SSB transmission may take place after 2N symbols after the current transmission. In this case, the combination of the PSS and the SSS is not used to indicate a cell ID. The PSS may indicate a validity area ID, and the particular combination of the PSS and the SSS indicates the next SSB transmission opportunity.

[0180] In a different embodiment, the combination of the PSS and the SSS may indicate that the next SSB transmission opportunity is dedicated to UL WUS occasions rather than the DL SSB occasion, as shown in FIG. 12. Similar to some previous implementations described above, the combination of the PSS and the SSS indicates that there are kN symbols until the next UL WUS occasion. Regarding the frequency and time resources for either full SSB transmissions or UL WUS occasions, there are predefined w ith respect to the PSS and SSS combination resource (frequency and time), for instance, the same relative frequency starting point and the symbol of SSS transmission. The SSB transmission and UL WUS occasions are the same for the entire validity area indicated by PSS for instance. This is possible when the PSS and the SSS are know n sequences. When the full SSB (i.e. including the MMIB) is received, the SSB may indicate a cell ID. In this case the SSB signal strength may be used for cell selection. In one implementation, MMIB and WUS frequency resources may be the same in a flexible symbol (either DL or UL).

[0181] In some implementations, WUS related configurations, including WUS transmission configuration and WUS response configuration, can be common to a number of cells / TRPs in an area. Then, the UE that has acquired WUS related configurations may use the same configurations to access more than one cell / TRP. In an embodiment, some of the cells / TRPs in the area may not turn on their SSB transmission until a WUS is received. The same WUS can be received by more than one cell / TRP, and the network can decide which cell / TRP to transmit the WUS response, for instance using the received WUS signal strength or the need for network coverage, etc. Alternatively, TRP1 may be monitoring the WUS and to receive WUS, but the network decides to have TRP2 which is not monitoring the WUS to transmit the WUS response. Upon the reception of WUS, a cell / TRP not transmitting the SSB may turn on its SSB transmission, and then interact with the UE on subsequent transmissions; that is, even the SSB transmission can be on-demand and triggered by the WUS. In one embodiment, on- demand SSB transmission is triggered by a certain WUS preamble (i.e., multiple WUS preambles are configured in MMIB), and some of the preambles may correspond to triggering on-demand SSB and associated RA configuration by another cell / TRP. In some embodiments, the WUS configuration for a cell / TRP with on-demand SSB is sentby another cell / TRP in its system information or RRC configuration information. The UE that has acquired the WUS configuration may send the WUS on the configured resource (for instance using a QCL transmission based on the received SSB for the cell that transmits the WUS configuration or the received WUS configuration signal itself) to trigger the on-demand SSB and hence the subsequent operations. Though the on- demand preamble transmission is called WUS transmission in some of these example embodiments for illustration purpose, the on-demand preamble transmission may also be a PRACH preamble transmission, on-demand preamble transmission, aperiodic preamble transmission, on-demand UL RS transmission, or UL WUS preamble transmission, etc.

[0182] FIG. 13 illustrates an example of the UE behavior for MMIB monitoring or MMIB request via the UL WUS, in accordance with some implementations. At the operation 1302, the UE searches for PSS / SSS transmission. At the operation 1304, the UE identifies the PSS / SSS sequence combination. At the operation 1306, the UE determines that whether the PSS / SSS indicates an MMIB transmission. If the answer is yes, the UE monitors for the MMIB at pre-configured or pre-defined locations w ith respect to PSS / SSS at the operation 1308. If the answer is no, at the operation 1310, the UE may transmit the UL WUS at pre-configured or pre-defined locations with respect to PSS / SSS.

[0183] Most of the implementations are described in a way more or less independent of beams or beamforming. The described techniques can also be adapted for cases with one or more beams or beamforming for a TDD system, such as for higher frequency of millimeter wave spectrum or upper middle band spectrum. For example, w hen n beams are needed to cover n different directions, each of the n beams can be implemented according to above implementations, and the n beams may be generally multiplexed in time-domain in a TDMed fashion. Both the network and the UE assume certain beam correspondence between the beams used for UL and DL. In some implementations, the same two-way spatial transmission parameters and spatial reception parameters can be assumed by the UE, or the spatial transmission parameters can be assumed as the same as the spatial reception parameters by the UE, or the spatial reception parameters can be assumed as the same as the spatial transmission parameters by the UE, each of which can be defined as a QCL relation for the UE.

[0184] The mechanism provided above can be used to deliver a RA configuration to a UE, allowing the UE to perform RA with the network. After completion of the RA procedure, the network can provide necessary information to the UE so that the UE can camp under the cell or connect to the cell. However, unicasting all this information,which could include the rest of the MIB, SIB1, and other SIBs, etc., could lead to high energy consumption and may not be always preferred, especially if the number of UEs is large. Alternatively, the information may be broadcast to UEs, such as sent together with the RA configuration. However, this may lead to a significant amount of periodic broadcast and hence may not be always suitable, either.

[0185] In some implementations, a tradeoff is provided. The necessary information can be periodically broadcast to the UEs, not with periodicity pt or t*pt, but with periodicity T*t*pi, where T > 1. In addition to the periodic broadcast, the information can also be triggered by UE, such as via certain PRACH preambles or resources, using essentially the same mechanism as described above. In other words, the delivery of necessary information (which may be called other SI, or SIB for simplicity) may adopt a multi-stage approach. In some multi-stage information delivery embodiments, the n-th stage carries the minimum information, i.e., the only information needed to receive the (n+i)-th stage (plus the accompanying DMRS, CRC, etc.), wherein the (n+i)-th stage transmission includes a higher payload or is configured w ith a longer periodicity than the n-th stage transmission. This is to reduce energy consumption, signal / signaling overhead, and network / UE processing complexity. In particular implementations, each transmission of the minimum information may include only the information explicitly described herein for that transmission, w ith no additional information elements.

[0186] The first stage is to acquire synchronization, WUS configuration, and RA configuration transmission resource information. The second stage is to acquire RA configuration and SIB transmission resource information, based on periodic broadcast of RA configuration or triggered RA configuration transmission. The third stage is to acquire SIB, wherein the SIB can be found either periodically, or can be triggered by PRACH preamble. Whenever the SIB is transmitted, it is in accordance with the indicated SIB transmission resource, which may be based on time / frequency-domain offset indicated by the SIB transmission resource information sent in the previous stage. Periodic SIB is not transmitted on every SIB transmission resource but “dow n sampled” with the longer periodicity. By now, the network transmits only broadcast (i.e., common) configuration information, and during this process the network does not identify the UE or the UE does not identify itself. That is, even if the UE transmits the WUS or the PRACH preamble, the UE does not send its UE ID of any sort. The network responses so far can be received and acquired by any UE that is monitoring. After the SIB is acquired, the UE can send a UE -specific request, similar to the legacy RA procedure, and acquire the rest of the configuration, generally the UE-specific configuration, so that the UE can complete the camping or RRC connection procedure.

[0187] FIG. 14 illustrates an example of the multi-stage procedure, in accordance with some implementations. As noted in the figure, a transmission in square brackets and w ith a dashed line is an optional transmission, such as UE’s WUS transmission, PRACH preamble transmission to request for other SI, etc.

[0188] The first several operations are similar to the WUS procedure described above. At the operation 1412, the NW (e.g., base station) 1404 broadcasts the PSS for the UE 1402 to perform the initial search and synchronization on time, frequency, and / or beam resources. At the operation 1414, the NW 1404 broadcasts the PDCH, the DMRS, and the MMIB to the UE 1402. The MMIB may include the WUS configuration (e.g., time / frequency offset), RA configuration transmission resource information (e.g., time / frequency offset), and the RA configuration transmission indicator. At the operation 1416, the UE 1402 transmits a WUS to the NW 1404 based on the PSS and the offset information indicated in the operation 1414. At the operation 1418, the NW 1404 broadcasts the PDCCH, PDSCH, and the RA configuration (e.g., time / frequency offset, preamble information) on the RA configuration transmission resource indicated in the operation 1414. At the operation 1420, the UE 1402 transmits the PRACH preamble in the PRACH as Msgt to request for other SI. However, at the operation 1422, when the response of the PRACH preamble (RAR) transmission is to broadcast other SI, it can be designed so that all UEs can receive the response. That is, a specific RAR to broadcast (common) SI can be designed. The PRACH preamble and the RAR (e.g. Msg2) may be seen as another WUS procedure. The RAR is sent on a preconfigured time / frequency- domain resource, w herein the resource is indicated in the RA configuration. The RAR may be scrambled based on certain SI-RNTI, instead of RA-RNTI. The PRACH preamble is not intended to distinguish different UEs as much as possible like in the conventional RA procedure, and hence, generally one specific PRACH preamble can be used, and one time / frequency-domain resource can be used. The same design for the WUS configuration can be reused, and in some embodiments, the same parameters can be used for simplicity. However, a difference between the WUS procedure and the RA procedure is that the RA procedure may deliver much more information, and hence in some cases, different parameters may be configured in the RA configuration.

[0189] As described before, the RAR does not have to be a response to a PRACH preamble; it can be broadcast periodically with periodicity T*t*pi. The same resource allocation parameters are used for either type of RAR transmission.

[0190] In some implementations, the RAR includes the allocation of one or more UL grants. The UL grants are not allocated to specific UEs, but each UL grant may be used by one or more UEs (e.g., in a contention-based w'ay). A UE (e.g., the UE 1402) can selectone UL grant and transmit its UE-specific request (e.g., Msg 3) there at the operation 1424, such as the cause for the request, certain UE ID, or scrambling sequence (such as RNTI) that may be common to multiple UEs, etc. When a conflict is identified by the network, the network can attempt to resolve the conflict, and for some UE may send the UL grant again. In the next operations 1426-1428, more UE-specific configurations and parameters can be exchanged betw een the network 1404 and the UE 1402, via PDCCH / PDSCH / PUSCH / etc., such as complete UE ID sent by the UE, C-RNTI and other RNTIs assigned by the network to the UE, configuration for camping and paging, configuration for RRC connection, and so on. The network 1404 may also configure the UE 1402 with UE-specific synchronization signal / tracking signal, such as a different SS or TRS for camping / paging / RRC connected state tracking QCL source, etc. Newly designed low-power WUS (LP-WUS) which can significantly reduce energy consumption may also be configured and utilized for idle / inactive UEs. Finally, at the operation 1430, the UE 1402 can complete its camping procedure or RRC connection establishment procedure, entering idle / inactive or connected state.

[0191] FIG. 15 illustrates an example of the signal and channel transmissions involving the multi-stage WUS procedure, on-demand + periodic RA configuration procedure, and on-demand + periodic SIB procedure. In Error! Reference source not found. 15, the top portion 1502 illustrates the periodic broadcasting of signals and channels. The SSB is sent w ith periodicity pt, represented by solid down arrows. The RA configuration is sent with periodicity t*pi, represented by dashed down arrows. The SIB is sent with periodicity T*t*pi, represented by dotted dow n arrow s. The RA indicators are not shown but the previously described mechanism applies here. Additionally, accompanied with each RA configuration transmission, there can be an “SIB indicator” whose value is from the set {o, 1, ..., T-1}, and it decreases by 1 every7time. When it reaches 0, SIB is transmitted, and the indicator is reset to T-1.

[0192] The middle portion 1504 of FIG. 15 illustrates the (almost) periodic monitoring by the network. It includes WUS monitoring windows (regular boxes) and PRACH preamble monitoring windows (patterned boxes). These correspond to the potential opportunities / occasions that a UE may transmit WUS or PRACH preamble. Though the monitoring can be fully periodically for every7SSB transmission (or for every RA configuration transmission in the case of PRACH preamble monitoring), for those SSB transmissions already accompanied by RA configuration transmission (or for those RA configuration transmissions already^ accompanied by SIB transmissions), there may not be a need for the network to monitor, and no need for the UE to transmit.

[0193] The bottom portion 1506 of Error! Reference source not found, illustrates the on-demand activities. The dotted up arrow represents the WUS transmission by a UE on a periodic WUS opportunity, and the network responds w ith the RA configuration on a periodic RA configuration transmission resource (dashed down arrow). The left dotted up arrow represents the PRACH preamble transmission by a UE on a periodic RACH opportunity, and the network responds with SIB on a periodic SIB transmission resource (dotted down arrow). The right dashed up arrow’ represents PRACH message transmission by a UE on an allocated UL grant related to a UE-specific request, and the network responds with UE-specific RRC configuration information (long dash down arrow).

[0194] FIG. 16 illustrates example implementations with the parameters and transmissions involving the multi-stage WUS procedure, on-demand + periodic RA configuration procedure, and on-demand + periodic SIB procedure. It includes the previously described RA indicator related design, adapts that design to include SIB indicator and SIB transmissions, and adds UE-specific configuration transmissions. At the operation 1602, the NW (e.g., base station) sets the RA indicator value based on t (the range of the RA indicator is from 0 to t-1) and sets the SIB indicator value based on T (the range of the SIB indicator is from o to T-1, and T is an integer multiple of t). At the operation 1604, the NW transmits at least one and any combination of the synchronization sequence, the WUS configuration, the RA configuration transmission information (e.g., RA configuration transmission resource), and the RA indicator. At the operation 1606, the NW determines whether (1) the NW receives a WUS, or (2) the RA indicator is o. If neither (1) or (2) is true, the NW moves to the operation 1608, w hich also covers the operation when either (1) or (2) is true. At the operation 1608, the NW performs the following procedure, assuming the current RA ind = tau, where tau is from the set {t-1, t-2, ..., 2, 1, 0}, the RA ind transmission period is pi, and the periodic transmission of the RA configuration is t*pi.(i) If the NW determines an out-of-sequence, aperiodic RA configuration transmission to be transmitted, the NW sets RA ind = a value chosen from {1, 2, ..., tau- 2} so that the aperiodic RA configuration will be sent sooner than waiting for another tau periods (i.e. , a latency of tau*pi).(ii) Otherwise, the NW sets RA ind according to its next position in the t periods (e.g., when it is taui periods (i.e., a latency of taui*pi) away from the next periodic RA configuration transmission, set RA ind = taui). This may include two cases, ii-a) If current tau >0 and corresponds to the actual position in the t periods, then the NW decreases the RA indicator by k (e.g., k= 1) ; ii-b) If current tau =0, the NW sets RAind = t-1, which corresponds to taut = t-1, i.e., when the current t*pi periods end, or the NW sets RA ind = taut if taut is less than t-1, which corresponds to the current RA configuration transmission w ith RA ind = o is an out-of-sequence, aperiodic RA configuration transmission.

[0195] Then, the flow proceeds to the operation 1604. If either of (1) or (2) is true, at the operation 1610, the NW transmits the RA configuration on the RA configuration transmission resource (indicated by the RA configuration transmission information transmitted at the operation 1602), the SIB transmission resource information, and the SIB indicator. At the operation 1612, the NW determines whether (a) the NW receives an RA preamble (b) the SIB indicator is 0. If neither (a) or (b) is true, the NW moves to the operation 1614, which also covers the operation when either (a) or (b) is true. At the operation 1614, the NW performs the follow ing procedure, assuming the current SIB ind = Tau, where Tau is from the set {T-1, T-2, ..., 2, 1, 0}, the SIB ind transmission period is t*pi, and the periodic transmission of SIB is T*t*pi.(i) If the NW determines an out-of-sequence, aperiodic SIB transmission to be transmitted, the NW sets SIB ind = a value chosen from {1, 2, ..., Tau-2} so that the aperiodic SIB will be sent sooner than waiting for another Tau periods (i.e., a latency of Tau*t*pi).(ii) Otherwise, the NW sets SIB ind according to its next position in the T periods ( e.g., when it is Taut periods (i.e., a latency of Tau*t*pi) away from the next periodic SIB transmission, set SIB ind = Taut). This may include two cases: ii-a) current Tau >0 and corresponds to the actual position in the T periods, then the NW decreases the SIB indicator by K (e.g., K=i); ii-b) current Tau =0, the NW sets SIB ind = T-i, which corresponds to Taut = T-i, i.e., when the current T*t*pi periods end, or the NW sets SIB ind = Taut if Taut is less than T-i, which corresponds to the current SIB transmission with SIB ind = o is an out-of-sequence, aperiodic SIB transmission. Then, the flow proceeds to the operation 1608. If either of (a) or (b) is true, at the operation 1616, the NW transmits the SIB on the SIB transmission resource (indicated by the SIB transmission resource information transmitted at the operation 1610) and the UL configuration. At the operation 1618, the NW determines whether the NW receives a UL grant. If the answer is no, the flow proceeds to the operation 1614. If the answer is yes, at the operation 1620, the NW transmits the system information / UE-specific configuration information, and the NW may receive additional information such the UE ID. The flow then proceeds to the operation 1614.

[0196] In some implementations, the second stage of acquiring RA configuration and the third stage of acquiring SIB may be combined, or some configuration information may be acquired in the second stage or the third stage. These may include the system frame number (SFN), control channel configuration, the cell ID, the cell configuration, the configuration for a SIB1 and other SIBs. In some implementations, UE does not acquire the SFN or the cell ID from the SSB (e.g., the SSB comprises two or more PSS symbols but no SSS symbols), then UE can acquire the SFN or the cell ID during the second or third stage. One example implementation is show n in the flowchart in FIG. 17, which combines some operations from the previous examples.

[0197] At the operation 1712, the NW (e.g., base station) 1704 broadcasts the PSS for the UE 1702 to perform the initial search and synchronization on time, frequency, and / or beam resources. At the operation 1714, the NW 1704 broadcasts the PDCH, the DMRS, and the MMIB to the UE 1702. The MMIB may include the SFN (optional: the LSBs of the SFN may be obtained from the RA indicator if transmitted), the SCS (optional: not needed if subsequent transmissions use the same SCS as the SSB), the WUS configuration (e.g., time / frequency offset), and the WUS reply configuration. At the operation 1716, the UE 1702 transmits a WUS with a WUS preamble based on the initial access (IA) sequence received at the operation 1712 and the offset information received at the operation 1714. At the operation 1718, the NW 1704 transmits the PDCCH, PDSCH, DMRS w ith other MIB information and a minimum SIB1. The minimum SIB1 may include RACH time / frequency / preamble information, which maybe non-UE-specific. At the operation 1720, the UE 1702 transmits the PRACH preamble in the PRACH as Msgt to request for the RAR. At the operation 1722, the NW 1704 transmits the PDCCH, PDSCH w ith the RAR as Msg2. The RAR may include the UL grant, the time advance (TA), the TC-RNTI, the transmission periodicity as UE-specific information. At the operation 1724, the UE 1702 transmits the PUSCH and DMRS with Msg3- The Msg3 may include the RRC connection request, the UE ID, and the connect cause. At the operation 1726, the NW 1704 transmits the PDCCH and PDSCH with Msg4- The Msg4 may include other SI information, camping information, and the C-RNTI. At the operation 1728, the UE 1702 can complete its camping procedure or RRC connection establishment procedure, entering idle / inactive or connected state.

[0198] In some embodiment, the SFN is acquired in multiple stages. For instance, the low er resolution SFN (LR SFN) can be provided with large period broadcasts (example the unit for indication can be N =128 slots, i.e. the indication is incremented every 128 slots), and the second stage w here a finer SFN indication (F SFN) can be the slot index in a group of N slots (i.e. the indication is incremented every slot). Forinstance, LR SFN may be provided in large period SSB transmission on some frequency raster, while the F SFN may be provided in SIB or shorter periods SSB transmission in a different frequency raster.

[0199] In some embodiments, the RA configuration in the second stage configures a 2-step RA procedure, which may be seen as another WUS procedure. A transmission of a PRACH preamble triggers a transmission of SIB, and no UE-specific information is involved. The response or RAR can be received by any UE and used by any UE to acquire SI. There is no contention of this process. One preamble can be configured for one type of response. For example, preamble 0 triggers the rest of MIB and SIB1 to be transmitted, preamble 1 triggers the rest of SIB2 to be transmitted, etc. Each preamble may be configured w ith a dedicated time-frequency domain resource, or multiple preambles share the same time-frequency domain resource and are differentiated by the preamble sequence (which may reduce resource overhead but may lead to collision). Each response may be configured with a dedicated time-frequency domain resource, or multiple responses share the same time-frequency domain resource for a search space or CORESET and are differentiated by a system RNTI or blind detection outcome. The RAR may not include UE-specific UL grant information. However, it may include non-UE- specific UL grant information, so that it can be used by the UE to request further configuration information in the subsequent steps. One example of such non-UE-specific UL grant information may be a regular RACH occasion information, so that the UE can initiate a regular 2 or 4-step RA since then. Issues of collision may arise, similar to legacy RA procedures, and similar collision resolution may be utilized.

[0200] In some embodiments, the RA configuration in the second stage configures a 4-step RA procedure. Multiple preambles are configured, and UE can pick one to perform contention-based RACH. After receiving a preamble, the network sends RAR with a UL grant assignment. Then UE receiving the RAR will transmit UE-specific information / request on the UL grant. One example of UE-specific information is a UE ID. One example of the UE-specific request is a connection request. Then the network will response accordingly to complete the RA procedure.

[0201] In some embodiments, the RA configuration in the second stage configures both a 2-step and 4-step RA procedures. This can be a combination of the above, and to differentiate the 2-step and 4-step RA procedures, different sets of PRACH preambles and / or time / frequency-domain resources can be configured.

[0202] In some embodiments, a first cell in the network can deliver MMIB configuration information plus RA configuration information for a second cell in thenetwork. The purpose is to reduce the number of transmissions by the second cell so that the second cell can be turned off. The second cell’s configuration information may be included in the first cell’s RA configuration transmission, especially if the two cells have the same (or similar) configuration for RA, in which case a field in the RA configuration can indicate that the configuration is applicable to a set of cells in a certain validity area, which are generally synchronized. The second cell’s configuration information may be included in the first cell’s RA message 2 or message 4 transmission, especially if the two cells have the different configurations for RA or asynchronous, in which case the RA configuration for the second cell can be included in part of the first cell’s SI transmission. Though the description is for the second cell’s RA configuration information acquisition, the design can be used to deliver the second cell’s other configuration information, e.g., SIB1, other SIBs, etc. The second cell’s SS or SSB may be transmitted in an on-demand way when the network (such as the first cell) receives a WUS or a PRACH preamble, which can be used to provide the UE with necessary time / frequency synchronization, AGC, resource reference, measurement, pathloss estimate, etc. of the second cell, based on which the UE can proceed to the next step such as the cell selection procedure, camping procedure, or initial access procedure, with the second cell.

[0203] In above multi-stage information delivery embodiments, the later stage(s) may use the same carrier resources / bandwddth part resources as the earlier stage, which can simplify UE and network implementations. However, in some cases, more carrier resources / bandwddth part resources are used to provide more capacity, especially when the later stage(s) may deliver hundreds, thousands, or even more bits, in the DL and / or UL directions, and some of the information delivery can be UE-specific or UE-group- specific. In an embodiment, WUS configuration information directs the UE to perform WUS transmission on a different carrier / bandwddth part, and subsequent operations are performed on those resources unless otherwise indicated by the network. In an embodiment, RA configuration information directs the UE to perform PRACH transmission on a different carrier / bandwddth part, and subsequent operations are performed on those resources unless otherwise indicated by the network. In an embodiment, SIB configuration information directs the UE to receive SIB transmission on a different carrier / bandwddth part, and subsequent operations are performed on those resources unless otherwise indicated by the network. UE-specific RRC configuration can be directed to a UE-specific carrier / bandwddth part.

[0204] Embodiments corresponding to FIG. 4 generally include periodic delivery of RA configuration information wdth periodicity t* pt and / or WUS triggered delivery of RA configuration information. A special case as illustrated in FIG. 18, which corresponds topossibly the “least interactive” initial access, is further elaborated. In this embodiment shown in FIG. 18, the WUS mechanism and / or the random access procedure are postponed in later stage (as late as possible, hence “least interactive”), and most transmissions are periodic broadcast. Compared to the more general embodiments shown in FIG. 4, the embodiment in FIG. 18 has lower complexity7for the network and for the UE (e.g., removing WUS related designs). For example, the MMIB can contain the following: coded bit field(s) to indicate RA configuration transmission resources; 2-3 (or maybe up to 4) bits for RA indicator indicating a sequence such as {o, 3, 2, 1, o, 3, 2, 1, o, ... } for how many more SSB instances before the RA configuration transmission, which are not a coded bit field but is conveyed via coding process parameters; and CRC of 8 (or at most, 16) bits; and the DMRS. As shown in FIG. 18, the MMIB is highly lightweight, since the payload is only to indicate the essential information for the UE to receive the next stage periodic transmission, which may be at most 8 bits. The flowchart for this embodiment corresponding to FIG. 18 is show n in FIG. 19.

[0205] FIG. 19 illustrates an example of the multi-stage procedure, in accordance w ith some implementations. The implementations represent the “least interactive" initial access approach, focusing on periodic broadcasting w ith minimal interaction. At the operation 1912, the NW (e.g., base station) 1904 broadcasts the PSS for the UE 1902 to perform the initial search and synchronization on time, frequency, and / or beam resources, with periodicity Pl. At the operation 1914, the NW 1904 broadcasts the PBCH, the DMRS, and the MMIB to the UE 1902. The MMIB may include the RA configuration transmission resource information (e.g., time / frequency offset) and the RA configuration transmission indicator. At the operation 1916, the NW 1904 broadcasts the PDCCH, PDSCH, and the RA configuration (e.g., time / frequency offset, preamble information) on the RA configuration transmission resource indicated in the operation 1914, with periodicity t*Pl. At the operation 1918, the UE 1902 transmits the PRACH preamble in the PRACH as Msgt to request for other SI. At the operation 1920, the NW 1904 transmits the PDCCH, PDSCH with the RAR as Msg2. The RAR may include other SI and a possible UL grant. At the operation 1922, the UE 1902 transmits Msg3 containing a UE-specific request. At the operation 1924, the NW 1904 transmits the PDCCH, PDSCH with Msg4- The Msg4 may include UE-specific configuration information, such as UE- specific UL grant. At the operation 1926, the NW 1904 transmits PDCCH, PDSCH, and the UE may transmit via PUSCH with other UE-specific information (e.g., camping information, C-RNTI, TRS configuration). At the operation 1928, the UE 1902 can complete its camping procedure or RRC connection establishment procedure, entering idle / inactive or connected state.

[0206] Another special case of FIG. 4 is illustrated in FIG. 20, which may be the “most interactive” initial access design. In this embodiment shown in FIG. 20, the system-wide periodic activities are reduced as much as possible (e.g., in FIG. 20, the only periodic activities at the network side is to periodically broadcast SSB and monitoring WUS). This significantly reduces the base energy consumption by a network, which is used for always-on activities to allow’ initial access. The procedure relies on on-demand transmissions as much as possible. That is, after the UE acquires the SSB, when the UE needs to proceed to the next step, it sends WUS to request more configuration information. Compared to the more general embodiments shown in FIG. 4, this embodiment has lower complexity for the network and the UE (i.e., removing periodic activities in later stages and their associated overhead). For example, the MMIB can contain the following: coded bit field(s) to indicate WUS configuration, including a fewbits for time / frequency-domain offset for WUS resources, a few- bits for WUS reply resources which cariy RA configuration or RA configuration transmission information, and, optionally, a few’ bits for the UE to know the WUS preamble configuration; CRC; and DMRS. The number of coded bits in MMIB bitfields may be lower than or equal to 8 bits, which makes the SSB very’ lightweight. FIG. 21 shows the flowchart corresponding to FIG. 20. Though the SFN and the SCS are listed in the flowchart, they are optional, as their values can be acquired in a next stage, and the information for this very initial stage is to just enable the WUS transmission and WUS reply reception of the next stage.

[0207] FIG. 21 illustrates an example of the multi-stage procedure, in accordance with some implementations. These implementations represent the “most interactive” initial access approach, focusing on on-demand transmissions triggered by UE requests. At the operation 2112, the NW (e.g., base station) 2104 broadcasts the PSS for the UE 2102 to perform the initial search and synchronization on time, frequency, and / or beam resources. The PSS includes the Initial Access (IA) sequence for synchronization. At the operation 2114, the NW 2104 broadcasts the PBCH, the DMRS, and the MMIB to the UE 2102. The MMIB may include the System Frame Number (SFN), Subcarrier Spacing (SCS), WUS transmission resource time / frequency offset, and WUS reply configuration. At the operation 2116, the UE 2102 transmits a WUS with a preamble based on the IA sequence and offset information received at the operation 2114. At the operation 2118, the NW 2104 transmits the PDCCH, PDSCH, DMRS with other MIB information and a minimum SIB1. The minimum SIB1 may include RACH time / frequency / preamble information, which is non-UE-specific. At the operation 2120, the UE 2102 transmits the PRACH preamble in the PRACH as Msgt to request for the RAR. At the operation 2122, the NW 2104 transmits the PDCCH, PDSCH with the RAR as Msg2. The RAR mayinclude the UL grant, Timing Advance (TA), Temporary C-RNTI (TC-RNTI), and Transmission Periodicity (TxP) as UE -specific information.

[0208] Despite of multi-stage information delivery during the initial access procedure, the latency experienced by the UE may be reduced while reducing the UE / network energy consumption at the same time, compared to the current 5G standards. The current 5G standards allow the gNB to turn off / prolong / reduce some transmissions to save energy, but latency and performance will suffer. In above embodiments, the latency can be reduced, since the lightweight SSB is intended to be more often than 5 ms, such as w ith periodicity of 1 ms, while still reducing power consumption because it carries only? PSS and fewer MMIB bits. The latency can also be reduced via interactive request later such as WUS transmission. Overall energy? reduction may be achieved from the lightweight SSB combined with much less often transmissions of higher payload size SIB1, or in general, lower payload transmissions can be done more often whereas higher payload transmissions are much less often or on-demand, thus achieving improved latency? performance and reduced energy consumption at the same time. In other words, the embodiments provide solutions to enable periodic, aperiodic (per network decision), and on-demand (per UE request) transmissions during initial access, w here low?-pay?load broadcast transmissions may? be configured with short periodicities, high-payload transmissions may be broadcast with longer periodicities and / or triggered by? UE request.

[0209] The above “least interactive” and “most interactive” may? be viewed as extreme cases of the general design illustrated in FIG. 4. There are a range of embodiments between the extremes, and the network can select from them to achieve desired balance among latency reduction, energy reduction, complexity, etc., and the network may adapt between a few embodiments based on UE density, traffic demand, traffic types, time of the day?, etc.

[0210] Most of the embodiments are described in a way more or less independent of beams or beamforming. The embodiment techniques can also be adapted for cases with one or more beams or beamforming for a TDD system, such as for higher frequency of millimeter wave spectrum or upper middle band spectrum. For example, when n beams are needed to cover n different directions, each of the n beams can be implemented according to above embodiments, and the n beams may be generally multiplexed in timedomain in a TDMed fashion. Both the network and UE assume certain beam correspondence between the beams used for UL and DL. In some embodiments, the same two-way spatial transmission parameters and spatial reception parameters can be assumed by? the UE, or the spatial transmission parameters can be assumed as the sameas the spatial reception parameters by the UE, or the spatial reception parameters can be assumed as the same as the spatial transmission parameters by the UE, each of which can be defined as a QCL relation for a UE.

[0211] Although this disclosure describes mainly based on symbols or OFDM symbols in the time domain, it can be adopted for other time-domain units based on other technologies, such as SC-FDM symbols, etc.

[0212] FIG. 22A shows a flowchart of a method 2200 performed by a network entity, in accordance with some implementations. The network entity may include computer- readable code or instructions executing on one or more processors of the network entity. Coding of the software for carrying out or performing the method 2200 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 2200 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non-transitoiy computer-readable medium, such as for example, at least one memory of the network entity. In some embodiments, the method 2200 may be performed by one or more of units or modules (e.g., an integrated circuit) of the network entity , such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0213] The method 2200 starts at the operation 2202, where the network entity transmits a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure or a cell search procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a second transmission resource for a second DL transmission of second configuration information. At the operation 2204, the network entity transmits the second DL transmission of the second configuration information using the second transmission resource in accordance with the first configuration information during the initial access procedure.

[0214] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted with a second periodicity. The first configuration information may’ include an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is transmitted.

[0215] In some implementations, the second periodicity may’ be an N multiple of the first periodicity. N may be an integer greater than 1.

[0216] In some implementations, the first configuration information may further indicate a first time or frequency domain resource for a first UL transmission. The network entity may receive the first UL transmission including a first UL sequence on the first time or frequency domain resource. To transmit the second DL transmission, the network entity may transmit the second DL transmission of the second configuration information in response to the receiving the first UL transmission.

[0217] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequencydomain sequence transmission, or the time-domain signal transmission.

[0218] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission may be received in a WUS monitoring window in accordance with the WUS monitoring window information.

[0219] In some implementations, the first configuration information may indicate the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0220] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted w ith a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

[0221] In some implementations, values of the indicator in the first plurality of DL transmissions may be in a sequentially decreasing order of (N-l, ..., 1, o). N may be an integer greater than 1. The network entity may reset the indicator to a different value than a current value of the indicator.

[0222] In some implementations, the first configuration information may indicate the second transmission resource by indicating a second time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0223] In some implementations, after the transmitting the second DL transmission, the network entity may receive a random access (RA) preamble in a physical randomaccess channel in accordance w ith the second configuration information or transmit a third DL transmission of third configuration information. The third DL transmission may include a higher payload or is configured w ith a longer periodicity than the second DL transmission.

[0224] In some implementations, the first configuration information may include only minimum information for the UE to obtain the second DL transmission of the second configuration information.

[0225] In some implementations, the first configuration information may only indicate the second transmission resource and may be accompanied only by a demodulation reference signal (DMRS) and a cyclic redundancy check (CRC).

[0226] In some implementations, the first plurality of DL transmissions may include a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence. The first configuration information may be betw een the first PSS and the second PSS in the time domain.

[0227] In some implementations, the network entity may include a plurality of base stations.

[0228] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0229] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0230] FIG. 22B shows a flowchart of a method 2220 performed by a network entity, in accordance with some implementations. The network entity may include computer- readable code or instructions executing on one or more processors of the network entity. Coding of the softw are for carrying out or performing the method 2220 is w ell within the scope of a person of ordinary7skill in the art having regard to the present disclosure. The method 2220 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non-transitoiy computer-readable medium, such as for example, at least one memory' of the network entity. In some embodiments, the method 2220 may be performed by one or more of units or modules (e.g., an integrated circuit) of the network entity7, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0231] The method 2220 starts at the operation 2222, where the network entity transmits a first plurality of downlink (DL) transmissions w ith a first periodicity during an initial access procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a first time or frequency domain resource for a first UL transmission and a second transmission resource for a second DL transmission of second configuration information. At the operation 2224, the network entity transmits the second DL transmission of the second configuration information using the second transmission resource in response to receiving the first UL transmission.

[0232] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, or a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission.

[0233] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission may be received in a WUS monitoring w indow in accordance with the WUS monitoring window information. The first configuration information may exclude information indicating a transmission occasion of the second DL transmission of the second configuration information.

[0234] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0235] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0236] FIG. 22C shows a flowchart of a method 2240 performed by a UE, in accordance with some implementations. The UE may include computer-readable code or instructions executing on one or more processors of the UE. Coding of the software for earn ing out or performing the method 2240 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 2240 may include additional or fewer operations than those show n and described and may be carried out or performed in a different order. Computer-readable code or instructions of the softw are executable by the one or more processors may be stored on at least one non-transitory computer-readable medium, such as for example, at least one memory of the UE. In some embodiments, the method 2240 may be performed by one or more of units or modules (e.g., an integrated circuit) of the UE, such as field programmable gate arrays (FPGAs) or application -specific integrated circuits (ASICs).

[0237] The method 2240 starts at the operation 2242, where the UE receives a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure or a cell search procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a second transmission resource for a second DL transmission of second configuration information. At the operation 2244, the UE performs at least one of time synchronization or frequency synchronization based on the first synchronization sequence. At the operation 2246, the UE receives the second DL transmission of the second configuration information using the second transmission resource in accordance with the first configuration information during the initial access procedure,

[0238] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions transmitted with a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is received.

[0239] In some implementations, the second periodicity may be an N multiple of the first periodicity. N may be an integer greater than 1.

[0240] In some implementations, the first configuration information may further indicate a first time or frequency domain resource for a first UL transmission. The UE may transmit the first UL transmission including a first UL sequence on the first time or frequency domain resource. The UE may receive the second DL transmission of the second configuration information in response to the transmitting the first UL transmission.

[0241] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission may exclude any information identifying the UE transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission.

[0242] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission may be transmitted in a WUS monitoring window in accordance with the WUS monitoring window information.

[0243] In some implementations, the first configuration information may indicate the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0244] In some implementations, the second DL transmission may be one of a second plurality of DL transmissions received with a second periodicity. The first configuration information may include an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

[0245] In some implementations, values of the indicator in the first plurality of DL transmissions may be in a sequentially decreasing order of (N-l, ..., 1, o). N may be an integer greater than 1. The indicator may be reset to a different value than a current value of the indicator.

[0246] In some implementations, the first configuration information may indicate the second transmission resource by indicating a second time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

[0247] In some implementations, after receiving the second DL transmission, the UE may transmit a random access (RA) preamble in a physical random access channel in accordance with the second configuration information or receive a third DL transmission of third configuration information. The third DL transmission may include a higher payload or is configured with a longer periodicity than the second DL transmission.

[0248] In some implementations, the first configuration information may include only minimum information for the UE to obtain the second DL transmission of the second configuration information.

[0249] In some implementations, the first configuration information may only indicate the second transmission resource and may be accompanied only by a demodulation reference signal (DMRS) and a cyclic redundancy check (CRC).

[0250] In some implementations, the first plurality of DL transmissions may include a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence. The first configuration information maybe between the first PSS and the second PSS in the time domain.

[0251] In some implementations, the first plurality of DL transmissions may be received from a network entity. The network entity may include a plurality of base stations.

[0252] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0253] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0254] FIG. 22D shows a flowchart of a method 2260 performed by a UE, in accordance w ith some implementations. The UE may include computer-readable code or instructions executing on one or more processors of the UE. Coding of the software for carrying out or performing the method 2260 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The method 2260 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on at least one non- transitory computer-readable medium, such as for example, at least one memory of the UE. In some embodiments, the method 2260 may be performed by one or more of units or modules (e.g., an integrated circuit) of the UE, such as field programmable gate arrays (FPGAs) or application -specific integrated circuits (ASICs).

[0255] The method 2260 starts at the operation 2262, where the UE receives a first plurality of downlink (DL) transmissions with a first periodicity during an initial access procedure or a cell search procedure. The first plurality of DL transmissions comprises a first synchronization sequence and first configuration information. The first configuration information indicates a first time or frequency domain resource for a first UL transmission and a second transmission resource for a second DL transmission of second configuration information. At the operation 2264, the UE performs at least one of time synchronization or frequency synchronization based on the first synchronization sequence. At the operation 2266, the UE receives the second DL transmission of the second configuration information using the second transmission resource in response to transmitting the first UL transmission during the initial access procedure.

[0256] In some implementations, the first UL transmission may include a UL wakeup signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission. The UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission mayexclude any information identifying the UE transmitting the UL WUS, the preamble transmission the frequency-domain sequence transmission, or the time-domain signal transmission.

[0257] In some implementations, the first configuration information may further indicate WUS monitoring window information. The first UL transmission maybe transmitted in a WUS monitoring window in accordance with the WUS monitoring window information. The first configuration information may exclude information indicating a transmission occasion of the second DL transmission of the second configuration information.

[0258] In some implementations, the second transmission resource may include at least one of a second time domain resource or a second frequency domain resource.

[0259] In some implementations, the second transmission resource may include at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

[0260] The network entity described in this disclosure may include a base station, a network relay node, or a plurality of base stations each configured to perform at least one of the network entity operations described above. For example, a first base station of the network entity may transmit the one or more RRC messages. A second base station of the network entity may receive the measurement report. The first base station or the second base station (or a third base station of the network entity) may transmit the cell switching command. In another example, a first base station of the network entity may transmit the one or more RRC messages. A second base station of the netw ork entity may transmit the PDCCH order. The first base station or the second base station (or a third base station of the network entity) may receive the random access preamble. The network entity operations may be distributed among different base stations in any combination or configuration, without limitation to the specific examples provided herein.

[0261] FIG. 23 illustrates an example communication system 2300. In general, the system 2300 enables multiple wireless or wired users to transmit and receive data and other content. The system 2300 may implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).

[0262] In this example, the communication system 2300 includes electronic devices (ED) 23103-23100, radio access networks (RANs) 232oa-232ob, a core network 2330, a public switched telephone network (PSTN) 2340, the Internet 2350, and other networks2360. While certain numbers of these components or elements are shown in FIG. 23, any number of these components or elements may be included in the system 2300.

[0263] The EDs 23103-23100 are configured to operate or communicate in the system 2300. For example, the EDs 23103-23100 are configured to transmit or receive via wireless or wired communication channels. Each ED 23103-23100 represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, AIoT device (e.g., for asset management), or consumer electronics device.

[0264] The RANs 232oa-232ob here include base stations 2370a-2370b, respectively. Each base station 2370a-2370b is configured to wirelessly interface with one or more of the EDs 23103-23100 to enable access to the core network 2330, the PSTN 2340, the Internet 2350, or the other networks 2360. For example, the base stations 2370a-2370b may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a gNB centralized unit (gNB-CU), a gNB distributed unit (gNB-DU), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 23103-23100 are configured to interface and communicate with the Internet 2350 and may access the core network 2330, the PSTN 2340, or the other networks 2360.

[0265] In the embodiment shown in FIG. 23, the base station 2370a forms part of the RAN 2320a, which may include other base stations, elements, or devices. Also, the base station 2370b forms part of the RAN 2320b, which may include other base stations, elements, or devices. Each base station 2370a-2370b operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multiple-input multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

[0266] The base stations 2370a-2370b communicate with one or more of the EDs 23103-23100 over one or more air interfaces 2390 using wireless communication links. The air interfaces 2390 may utilize any suitable radio access technology.

[0267] It is contemplated that the system 2300 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New- Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

[0268] The RANs 23203-23205 are in communication with the core network 2330 to provide the EDs 23103-23100 w ith voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs 232oa-232ob or the core network 2330 may be in direct or indirect communication with one or more other RANs (not shown). The core network 2330 may also serve as a gateway access for other networks (such as the PSTN 2340, the Internet 2350, and the other networks 2360). In addition, some or all of the EDs 23103-23100 may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of w ireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not show n), and to the Internet 2350.

[0269] Although FIG. 23 illustrates one example of a communication system, various changes may be made to FIG. 23. For example, the communication system 2300 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0270] FIGs. 24A and 24B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, FIG. 24A illustrates an example ED 2410, and FIG. 24B illustrates an example base station 2470. These components could be used in the system 2300 or in any other suitable system.

[0271] As shown in FIG. 24A, the ED 2410 includes at least one processing unit 2400. The processing unit 2400 implements various processing operations of the ED 2410. For example, the processing unit 2400 could perform signal coding, data processing, power control, input / output processing, or any other functionality enabling the ED 2410 to operate in the system 2300. The processing unit 2400 also supports the methods and teachings described in more detail above. Each processing unit 2400 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 2400 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0272] The ED 2410 also includes at least one transceiver 2402. The transceiver 2402 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 2404. The transceiver 2402 is also configured to demodulate data or other content received by the at least one antenna 2404. Each transceiver 2402 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna2404 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 2402 could be used in the ED 2410, and one or multiple antennas 2404 could be used in the ED 2410. Although showoi as a single functional unit, a transceiver 2402 could also be implemented using at least one transmitter and at least one separate receiver.

[0273] The ED 2410 further includes one or more input / output devices 2406 or interfaces (such as a wired interface to the Internet 2350). The input / output devices 2406 facilitate interaction with a user or other devices (network communications) in the network. Each input / output device 2406 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.[02741 In addition, the ED 2410 includes at least one memory 2408. The memory 2408 stores instructions and data used, generated, or collected by the ED 2410. For example, the memory 2408 could store software or firmware instructions executed by the processing unit(s) 2400 and data used to reduce or eliminate interference in incoming signals. Each memory 2408 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memoiy (RAM), read only memoiy (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.

[0275] As shown in FIG. 24B, the base station 2470 includes at least one processing unit 2450, at least one transceiver 2452, w hich includes functionality for a transmitter and a receiver, one or more antennas 2456, at least one memory 2458, and one or more input / output devices or interfaces 2466. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 2450. The scheduler could be included within or operated separately from the base station 2470. The processing unit 2450 implements various processing operations of the base station 2470, such as signal coding, data processing, power control, input / output processing, or any other functionality. The processing unit 2450 can also support the methods and teachings described in more detail above. Each processing unit 2450 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 2450 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0276] Each transceiver 2452 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver2452 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 2452, a transmitter and a receiver could be separate components. Each antenna 2456 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 2456 is shown here as being coupled to the transceiver 2452, one or more antennas 2456 could be coupled to the transceiver(s) 2452, allowing separate antennas 2456 to be coupled to the transmitter and the receiver if equipped as separate components. Each memoiy 2458 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input / output device 2466 facilitates interaction with a user or other devices (network communications) in the network. Each input / output device 2466 includes any suitable structure for providing information to or receiving / providing information from a user, including network interface communications.

[0277] FIG. 25 is a block diagram of a computing system 2500 that may be used for implementing the devices and methods disclosed herein. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components show n or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 2500 includes a processing unit 2502. The processing unit includes a central processing unit (CPU) 2514, memory 2508, and may further include a mass storage device 2504, a video adapter 2510, and an I / O interface 2512 connected to a bus 2520.

[0278] The bus 2520 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 2514 may comprise any type of electronic data processor. The memoiy 2508 may comprise any type of non-transitory system memoiy such as static random access memoiy (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memoiy 2508 may include ROM for use at boot-up, and DRAM for program and data storage for use w hile executing programs.

[0279] The mass storage 2504 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 2520. The mass storage 2504may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0280] The video adapter 2510 and the I / O interface 2512 provide interfaces to couple external input and output devices to the processing unit 2502. As illustrated, examples of input and output devices include a display 2518 coupled to the video adapter 2510 and a mouse, keyboard, or printer 2516 coupled to the I / O interface 2512. Other devices may be coupled to the processing unit 2502, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

[0281] The processing unit 2502 also includes one or more network interfaces 2506, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 2506 allow the processing unit 2502 to communicate with remote units via the networks. For example, the network interfaces 2506 may provide wireless communication via one or more transmitters / transmit antennas and one or more receivers / receive antennas. In an embodiment, the processing unit 2502 is coupled to a local-area network 2522 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0282] It should be appreciated that not all components in the devices described in FIG. 19-21 are required. In a non-limiting example, the ED 2010 maybe implemented as an AIoT device 2010. But, the AIoT device 2010 may not include an input / output devices 2006 for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen. The transceiver 2002 of the AIoT device 2010 may be capable of transmitting by backscattering a radio wave received, instead of by generating the radio wave, for wireless communication purpose. In another non-limiting example, the system 2100 may be implemented as an AIoT device 2100 that does not include or use the mass storage device 2104, the video adapter 2110, the mouse, keyboard, or printer 2116, or the display 2118.

[0283] It should be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a performing unit or module, a generating unit or module, an obtaining unit or module, a setting unit or module, an adjusting unit or module, an increasing unit or module, a decreasing unitor module, a determining unit or module, a modifying unit or module, a reducing unit or module, a removing unit or module, or a selecting unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0284] Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

WHAT IS CLAIMED IS:

1. A method, comprising: during an initial access procedure: transmitting, by a network entity, a first plurality7of downlink (DL) transmissions with a first periodicity, the first plurality of DL transmissions comprising a first synchronization sequence and first configuration information, wherein the first configuration information indicates a second transmission resource for a second DL transmission of second configuration information; and transmitting, by the network entity, the second DL transmission of the second configuration information using the second transmission resource in accordance with the first configuration information.

2. The method of claim 1, wherein the second DL transmission is one of a second plurality of DL transmissions transmitted with a second periodicity, and wherein the first configuration information includes an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is transmitted.

3. The method of claim 2, wherein the second periodicity is an N multiple of the first periodicity, and N is an integer greater than 1.

4. The method of any of claims 1-3, wherein the first configuration information further indicates a first time or frequency domain resource for a first UL transmission, the method further comprising: receiving, by the network entity, the first UL transmission including a first UL sequence on the first time or frequency domain resource, wherein the transmitting the second DL transmission comprises: transmitting, by the network entity, the second DL transmission of the second configuration information in response to the receiving the first UL transmission.

5. The method of claim 4, wherein the first UL transmission includes a UL wake-up signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission, the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission excluding any information identifying a user equipment (UE) transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the timedomain signal transmission.

6. The method of claim 5, wherein the first configuration information further indicates WUS monitoring w indow information, and the first UL transmission is received in a WUS monitoring wdndow in accordance w ith the WUS monitoring window information.

7. The method of claim 4, w herein the first configuration information indicates the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

8. The method of claim 4, wherein the second DL transmission is one of a second plurality of DL transmissions transmitted with a second periodicity, and wherein the first configuration information includes an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

9. The method of claim 8, w herein values of the indicator in the first plurality of DL transmissions are in a sequentially decreasing order of (N-1, ..., 1, 0), N being an integer greater than 1, and the method further comprising: resetting, by the network entity, the indicator to a different value than a current value of the indicator.

10. The method of any of claims 1-9, wherein the first configuration information indicates the second transmission resource by indicating a second time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

11. The method of any of claims 1-10, further comprising: after the transmitting the second DL transmission, receiving a random access (RA) preamble in a physical random access channel in accordance with the second configuration information, or transmitting a third DL transmission of third configuration information, w herein the third DL transmission includes a higher payload or is configured with a longer periodicity than the second DL transmission.

12. The method of any of claims 1-11, the first configuration information including only minimum information for the UE to obtain the second DL transmission of the second configuration information.

13. The method of claim 1-12, the first configuration information only indicating the second transmission resource.14- The method of any of claims 1-13, wherein the first plurality of DL transmissions includes a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence, and wherein the first configuration information is between the first PSS and the second PSS in the time domain.

15. The method of any of claims 1-14, wherein the network entity includes a plurality of base stations.

16. The method of any of claims 1-15, the second transmission resource including at least one of a second time domain resource or a second frequency domain resource.

17. The method of any of claims 1-15, the second transmission resource including at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

18. A method, comprising: during an initial access procedure or a cell search procedure: receiving, by a user equipment (UE), a first plurality of downlink (DL) transmissions with a first periodicity, the first plurality of DL transmissions comprising a first synchronization sequence and first configuration information, and wherein the first configuration information indicates a second transmission resource for a second DL transmission of second configuration information; performing, by the UE, at least one of time synchronization or frequency synchronization based on the first synchronization sequence; and receiving, by the UE, the second DL transmission of the second configuration information using the second transmission resource in accordance with the first configuration information.

19. The method of claim 18, wherein the second DL transmission is one of a second plurality of DL transmissions transmitted w ith a second periodicity, and wherein the first configuration information includes an indicator indicating a number of periods associated with the first periodicity relative to a current period before the second DL transmission is received.

20. The method of claim 19, wherein the second periodicity is an N multiple of the first periodicity, and N is an integer greater than 1.

21. The method of any of claims 18-20, wherein the first configuration information further indicates a first time or frequency domain resource for a first UL transmission, the method further comprising: transmitting, by the UE, the first UL transmission including a first UL sequence on the first time or frequency domain resource, wherein the receiving the second DL transmission comprises: receiving, by the UE, the second DL transmission of the second configuration information in response to the transmitting the first UL transmission.

22. The method of claim 21, wherein the first UL transmission includes a UL wake-up signal (WUS), a preamble transmission, a frequency-domain sequence transmission, or a time-domain signal transmission, the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission excluding any information identifying the UE transmitting the UL WUS, the preamble transmission, the frequency-domain sequence transmission, or the time-domain signal transmission.

23. The method of claim 22, wherein the first configuration information further indicates WUS monitoring window information, and the first UL transmission is transmitted in a WUS monitoring window- in accordance with the WUS monitoring window information.

24. The method of claim 21, wherein the first configuration information indicates the first time or frequency domain resource by indicating a first time or frequency domain offset from a time or frequency domain resource of the first synchronization sequence.

25. The method of claim 21, wherein the second DL transmission is one of a second plurality of DL transmissions received with a second periodicity, and wherein the first configuration information includes an indicator indicating a number of periods associated with the first periodicity from a current period to the second DL transmission.

26. The method of claim 25, wherein values of the indicator in the first plurality of DL transmissions are in a sequentially decreasing order of (N-1, ..., 1, 0), N being an integer greater than 1, and wherein the indicator is reset to a different value than a current value of the indicator.

27. The method of any of claims 18-26, wherein the first configuration information indicates the second transmission resource by indicating a second time or frequencydomain offset from a time or frequency domain resource of the first synchronization sequence.

28. The method of any of claims 18-27, further comprising: after the receiving the second DL transmission, transmitting a random access (RA) preamble in a physical random access channel in accordance with the second configuration information, or receiving a third DL transmission of third configuration information, wherein the third DL transmission includes a higher payload with a longer periodicity than the second DL transmission.

29. The method of any of claims 18-28, the first configuration information including only minimum information for the UE to obtain the second DL transmission of the second configuration information.

30. The method of claim 18-29, the first configuration information only indicating the second transmission resource.

31. The method of any of claims 18-30, wherein the first plurality of DL transmissions includes a first primary synchronization signal (PSS) including the first synchronization sequence and a second PSS including the first synchronization sequence, and wherein the first configuration information is between the first PSS and the second PSS in the time domain.

32. The method of any of claims 18-31, wherein the first plurality of DL transmissions is received from a network entity, and wherein the network entity includes a plurality of base stations.

33. The method of any of claims 18-32, the second transmission resource including at least one of a second time domain resource or a second frequency domain resource.

34. The method of any of claims 18-32, the second transmission resource including at least one of a second time domain resource, a second frequency domain resource, a second spatial domain resource, or a second coding domain resource.

35. A network entity comprising: at least one processor; and at least one non-transitoiy computer readable storage medium storing programming, the programming including instructions that, when executed by the atleast one processor, cause the network entity to perform a method according to any of claims 1-17.

36. A user equipment (UE) comprising: at least one processor; and at least one non-transitoiy computer readable storage medium storing programming, the programming including instructions that, when executed by the at least one processor, cause the UE to perform a method according to any of claims 18-34.

37. A non-transitoiy computer-readable medium having instructions stored thereon that, when executed by a network entity, cause the network entity to perform a method according to any of claims 1-17.

38. A non-transitoi ’ computer-readable medium having instructions stored thereon that, when executed by a user equipment (UE), cause the UE to perform a method according to any of claims 18-34.

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