CN116325951A - Wake-up signal in cellular system - Google Patents

Abstract

Methods and modes for transmitting wake-up signals in a beam scanning cellular communication system. At least one wake-up signal is transmitted in bursts on each beam.

Description

Wake-up signal in cellular system

Technical Field

The following disclosure relates to the transmission of wake-up signals in cellular networks, and in particular to the transmission of such signals in beam scanning systems.

Background

Wireless communication systems such as the third generation (3G) mobile telephone standard and technology are well known. Such 3G standards and technologies have been developed by the third generation partnership project (Third Generation Partne rship Project,3 GPP) (RTM). Third generation wireless communications have been developed in general to support macrocell mobile telephone communications. Communication systems and networks have evolved to broadband and mobile systems.

In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (Radio Access Network, RAN) by a wireless link. The RAN includes a set of base stations that provide radio links to a plurality of UEs located in a cell covered by the base stations, and an interface to a Core Network (CN) that provides overall network control. It should be appreciated that the RAN and CN each perform a respective function related to the overall network. For convenience, the term cellular network will be used to refer to the combination of the RAN and CN, and it will be understood that the term is used to refer to the corresponding system for performing the disclosed functions.

The third generation partnership project has developed a so-called long term evolution (Long Term Evolutio n, LTE) system, i.e. an evolved universal mobile telecommunications system terrestrially received radio access network (Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, E-UTRAN) for mobile access networks in which one or more macro cells are supported by base stations called eNod eB or eNB (evolved NodeB). Recently, LTE is further evolving towards so-called 5G or New Radio (NR) systems, where one or more cells are supported by base stations called gnbs. NR is proposed to use an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexed, OFDM) physical transport format.

The above-described NR protocol (referred to as NR-U) is intended to provide an option for operation in unlicensed radio bands. When operating in the unlicensed radio band, the gNB and UE must compete for physical media/resource access with other devices. For example, wi-Fi (RTM), NR-U, and Licensed-assisted Access (License Assisted Access, LAA) may utilize the same physical resources.

The trend in wireless communication is toward the provision of lower latency and higher reliability services. For example, NR is intended to support Ultra-reliable and low-latency communication (URLLC), while large-scale Machine-type communication (mMTC) is intended to provide low latency and high reliability for small packet sizes (typically 32 bytes). A user plane delay of 1 millisecond (ms) and a reliability of 99.99999% have been proposed, and a method of determining the physical delay in the physical delay has been proposed Layer 10 ^-5 Or 10 ^-6 Packet loss rate of (a).

The mctc service supports a large number of devices over a long lifecycle through an energy efficient communication channel, where data transmissions with each device are sporadic and infrequent. For example, one cell may need to support thousands of devices.

The following disclosure relates to various improvements to cellular wireless communication systems.

Publication contents

Summary of the inventionsome concepts are presented in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

A method of transmitting a wake-up signal from a base station to a UE in a cellular communication system, wherein the base station transmits a plurality of beams, the method comprising transmitting a burst of wake-up signals, the burst comprising at least one wake-up signal per beam. The wake-up signal burst may be transmitted a predefined time offset before a paging occasion associated with the wake-up signal burst. The time offset may be defined as a time from an end of the wake-up signal burst to a start of the paging occasion. The wake-up signal of the burst may be continuously transmitted in adjacent symbols. The wake-up signal may be frequency domain multiplexed with a synchronization signal (synchronizati on signal, SS)/physical broadcast channel (Physical Broadcast Channel, PBCH), system information block SIB1, or physical downlink control channel (Physical Downlink Control Channel, PDCCH) signal.

The at least one wake-up signal for each beam may be the same or the wake-up signal may vary between beams. The at least one wake-up signal may comprise a base sequence with a cyclic shift dependent on the beam.

There is provided a method of transmitting a wake-up signal from a base station to a UE in a cellular communication system, wherein the base station transmits a plurality of beams, the method comprising transmitting a burst of wake-up signals, the burst comprising at least one wake-up signal transmitted on each beam, wherein the burst of wake-up signals is arranged not to be transmitted during a control transmission.

The wake-up signal burst is transmitted a predefined time offset before a paging occasion associated with the wake-up signal burst.

The time offset may be defined as a time from an end of the wake-up signal burst to a start of the paging occasion.

Wake-up signals on at least two beams may be transmitted in a set of adjacent symbols.

The set of adjacent symbols may span the handoff between beams.

The burst may span at least two time slots.

The wake-up signal may be frequency domain multiplexed with SS/PBCH, SIB1 or PDCCH signals.

The multiplexing configuration may be defined by upper layer signaling.

The length of the at least one wake-up signal on one beam may be the same as the length of the signal multiplexed therewith.

The at least one wake-up signal on at least two of the beams may be the same.

The at least one wake-up signal on each beam may be different.

The at least one wake-up signal on each beam may comprise a base sequence with a cyclic shift dependent on the beam.

The at least one wake-up signal on each beam may utilize a different root of the Zadoff-Chu sequence.

The at least one wake-up signal on each beam may have a length of between 1 and 4 symbols.

The at least one wake-up signal on each beam may be repeated.

The starting position of the wake-up signal burst may be signaled to the user equipment UE in upper layer signaling.

A synchronization signal block (synchronization signal block, SSB) occasion occurs between the at least one wake-up signal on one beam and the paging occasion to which the wake-up signal relates.

The at least one wake-up signal may be a group wake-up signal.

The at least one wake-up signal may be a common wake-up signal for all UEs.

The group wake-up signal may be calculated as

Is defined by the cyclic shift g of the base sequence of +.>

Is the group identifier ID determined by the upper layer protocol.

The wake-up signal may be sequence based.

The method may further comprise the step of selecting a time-frequency transmission mode for the wake-up signal and indicating this mode to the user equipment UE.

There is provided a base station performing the method of any of the preceding claims.

Drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the corresponding drawings for ease of understanding.

Fig. 1 shows selected elements of a cellular communication system;

fig. 2 shows an example burst of Wake-Up Signal (WUS);

FIG. 3 shows an example burst of WUS and associated paging occasion;

fig. 4 to 6 show examples of WUS multiplexing with SS/PBCH;

FIGS. 7-9 show examples of WUS multiplexing with SIB1 and other signals;

FIG. 10 shows the configuration of WUS of version 15 (R15); a kind of electronic device with high-pressure air-conditioning system

Figures 11 to 16 show a configurable WUS pattern.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Fig. 1 shows a schematic diagram of three base stations (e.g., enbs or gnbs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each of the base stations will be deployed by one cellular network operator to provide geographic coverage for UEs in its area. The base stations form a radio area network (Radio Ar ea Network, RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected by the X2 interface and connected to the core network by the S1 interface. It should be understood that only basic details are shown for the purpose of illustrating key features of a cellular network. A PC5 interface is provided between UEs for side-chain (SL) communication. The interface and component names described in connection with fig. 1 are for example only, and different systems operate on the same principles, possibly using different nomenclature.

Each of the base stations includes hardware and software to implement the functions of the RAN, including communication with the core network and other base stations, transmission of control and data signals between the core network and UEs, and maintaining wireless communication of UEs associated with each base station. The core network includes hardware and software that implements the network functions, such as overall network management and control, and routing of calls and data.

For certain classes of devices operating in a cellular network, power consumption is a critical parameter. The 3GPP has specified in LTE a Machine Type Communication (MTC) UE type for implementation of industrial sensors and the like devices that are expected to operate for years with a single battery charge. For static and mobile devices (inte rnet of things, ioT), the NB-IoT standard described above may be used.

To reduce power consumption, such devices may spend a significant amount of time in rrc_idle/INACTIVE mode, shutting down their radio system with discontinuous reception (discontinuous reception, DRX), waking up only to listen for paging messages. Although the paging occasions for possible reception of paging messages are not very frequent, the process of decoding paging messages is complex and consumes a relatively large amount of power. For example, the UE must wake up before an expected Paging Occasion (PO), turn on the RF and baseband systems, synchronize in time and frequency, and attempt to decode the PDCCH to obtain Paging DCI scrambled with a Paging radio network temporary identifier (Paging Radio Network Tempory Identity, RNTI). The UE may return to sleep (DRX) if paging downlink control information (downlink control information, DC I) is not detected. The above procedure may require several frames, and depending on the number of repetitions of the PDCCH, PDCCH decoding is relatively complex. To reduce this complexity, a Wake-Up Signal (WUS) may be sent for detection by the UE before the paging occasion at which the paging message is to be sent to the UE. The WUS is typically sequence based for easy detection without decoding and baseband processing. The UE is configured to wake up first to detect WUS and if a signal of the UE is detected, the UE wakes up completely to receive the PDCCH at an appropriate time because a paging message is believed to exist. If the WUS is not detected, the UE may return to sleep. The reduced complexity of detecting WUS, which may be performed using a correlator (correlator), may reduce power consumption compared to performing full PDCCH decoding.

The DRX system utilizes a DRX cycle in which one or more POs are defined. The DRX/paging cycle may be indicated in SIB1 or may be negotiated during Non-access stratum (NAS) registration for a UE-specific DRX cycle (UE-specific DRX cycle). Typically, the paging cycle is 32, 64, 128 or 256 radio frames. The Paging Frame and Paging Occasion are defined according to the relevant standards, e.g. TS 38.304.

The WUS at rrc_idle/INACTIVE is mainly used for power saving for low power UEs and robust detection is important. Previous systems have used time repetition and use the synchronization signals required for time-frequency synchronization prior to PDCCH detection to seek to provide robustness. However, in NR, the synchronization signal has a configurable periodicity, and beam scanning (especially in FR 2) requires that the transmission on each beam is very short. Repeated transmissions lasting several milliseconds or long WUS are not supported.

Described in the following disclosure are techniques for providing a highly efficient WUS system, particularly for beam scanning systems operating at high frequencies.

MTC and NB-IoT devices support bandwidths of 1.4MHz, while reduced performance (reduced capability, REDCAP) NR devices are expected to support at least 20MHz in FR1 and 50 to 100MHz in FR 2. These additional resources may be used for longer WUS sequences, or WUS repetition in the frequency domain, rather than time domain repetition.

In the following disclosure, it is assumed that the WUS can be transmitted anywhere in the available time-frequency resources, can have any duration measured in OFDM symbols, and the duration and the start or end of the WUS are known from a pre-configuration.

Since paging messages must be transmitted on all beams, the associated WUS must also be transmitted on all beams. To achieve this, WUS burst transmission on each beam is utilized. Fig. 2 shows an example of such burst transmission for 4 beams, wherein the burst comprises at least one WUS for each beam (WUS being the same on each beam). The WUS duration of each beam is kept short, in this example 5 symbols, to manage the time required for the beam scanning operation. The starting position of each WUS transmission (on each beam) may be specified by the standard or configured for each base station, e.g. using upper layer (radio resource control (Radio Resource Control, RRC)) signaling. The starting position of each WUS in a burst will depend on the duration of the WUS.

Generally, throughout this disclosure, one or more WUSs may be transmitted on resources indicated to WUSs. For clarity of description only, WUS is referred to in the singular, but this does not preclude the transmission of multiple WUS.

In order to avoid collision with PDCCH and PUCCH, WUS is not transmitted in the first two or last two symbols of each slot. WUS may also preferably not be transmitted in the middle of a slot to avoid collisions with PDCCH or PUCCH for URLLC transmissions.

During the transmission, the WUS transmission may be continuous in time as the base station switches beams. However, this is not possible for longer WUS while avoiding control transmissions at the beginning and end of each slot. As can be seen in fig. 2, only two WUS can be transmitted consecutively without overlapping the control transmissions at the beginning and end of the time slot. In the case of WUS continuous transmission, only the start position and duration need be defined.

FR1 in NR is intended to support up to 4 beams for carrier frequencies +.3 GHz, and up to 8 beams between 3GHz and 6 GHz.

Tables 1 and 2 below show possible starting positions for a 4-beam and 9-beam 15kHz subcarrier Spacing (SCS), respectively.

Table 1: examples of WUS start positions of 15kHz SCS and FR 1. Ltoreq.3 GHz (maximum 4 beams).

Table 2: examples of WUS start positions of 15kHz SCS and FR1>3 GHz.ltoreq.6 GHz (up to 8 beams).

Tables 3 and 4 show possible starting positions for 4 and 8 beams of 30kHz SCS, respectively.

Table 3: examples of WUS start positions for 30kHz SCS and FR1 z.ltoreq.3 GHz (maximum 4 beams).

Table 4: examples of WUS start positions for 30kHz SCS and FR1 > 3 GHz.ltoreq.6 GHz (up to 8 beams).

Tables 5 and 6 show possible starting positions for the 64 beams when operating in FR2 of 120kHz and 240kHz SCS, respectively.

Table 5: examples of WUS start positions for 120kHz SCS and FR2>6GHz (up to 64 beams). There are 112 slots in a subframe, n= 0,1,2,3,5,6,7,8, 10, 11, 12, 13, 15, 16, 17, 18.

Table 6: examples of WUS start positions for 240kHz SCS and FR2>6GHz (up to 64 beams). There are 112 slots in a subframe, n= 0,1,2,3,5,6,7,8.

To simplify the configuration and scheduling in the time domain, the WUS length may be limited to, for example, 1 or 4 symbols, and the coverage is increased by spreading/repeating the WUS in the frequency domain or the time domain.

As shown in fig. 3, the WUS bursts are associated with the POs according to a defined time offset. In the example of fig. 3, the POs occurs in SFN 64 and 4 PDCCH opportunities (one per beam) are configured. In the example of fig. 3, the time offset, which may be defined by upper layer configuration and signaling, is defined between the last slot of the WUS burst and the first slot of the PO (not between WUS for a beam and PDCCH monitoring occasions on the same beam). The PDCCH for each PO is configured via a search space (search space) and an associated Control-resource set (CORESET). The WUS has its own duration, which may be longer than the CORESET duration of the associated PDCC H. Thus, defining delays based on the burst opportunities is motivated by the fact that the same time offset per beam may not be applied due to the different durations/configurations of the signals. The time offset may be defined as an absolute time in milliseconds, or another convenient set of units.

Table 7 shows possible configurations of SSB periods and example values of the time offset between the end of the WUS burst and the start of the PO.

SSB period ssbPeriology [ ms ]]	5,10,20,40,80,160
		Time offset [ ms ]]	5,10,20,40,80,160,320

Table 7: examples of possible values for the time offset.

In the case where the WUS is frequency domain multiplexed with the SS/PBCH transmissions (as described below), the shorter offsets of 5ms and 10ms may be beneficial, in which case the UE will detect both WUS and SS/PBCH and be ready to decode paging messages soon. In general, the time offset should be defined such that SSB opportunities occur at least once between the WUS and the PO so that the UE can synchronize and acknowledge with the serving cell.

To avoid specific beam scanning to transmit the WUS, the WUS can be multiplexed with other signals that need to be transmitted. Cell-wide signals, such as SS/PBCH or SIB1 type 0 common search space, may be particularly suitable for multiplexing. The specific multiplexing configuration may be configured by upper layer signaling, such as RRC.

For example using frequency domain multiplexing of SS/PBCH, it may be most beneficial when the two signals have the same length, but the principle can still be applied when the lengths are different. Preferably, the SCSs of the multiplexed transmission are identical to avoid gaps in frequency usage.

Fig. 4 and 5 show examples of 4 symbol WUS frequencies multiplexed with 4 symbol SS/PBCH. The particular multiplexing settings may be selected based on available resources and the settings of the figures are shown as examples only.

In the example of fig. 6, two SS/PBCHs from one burst are shown, each transmitting on a different beam. WUS is multiplexed with two transmissions and transmissions of WUS also continue between the transmissions. The base station may select any direction for the intervening transmissions to optimize performance. If the intermediate time would interfere with the search space for control signaling, the base station may not make any transmissions and suspend WUS transmissions until the next SS/PBCH symbol.

Fig. 7 shows an example of WUS multiplexing with SS/PBCH in FR2 for multiplexing mode 3, where the paging search space configuration is the same as searchSpaceZero.

The time offset discussed above describes the offset as a multiple of the SSB period if the WUS is frequency domain multiplexed with the SS/PBCH. The time offset is thus the time between the start of the WUS burst and the start of the first PDCCH monitoring occasion of the associated PO. For example, if the SSB period is 20ms and the time offset is 80ms, WUS is transmitted with SS/PBCH 8 frames before the associated PO.

In the specific example of FR2 with multiplexing mode 2 and the same paging search space as search space zero, WUS can be multiplexed with CSS0 because PDCCH is time interleaved with the SS/PBC H/SIB1 transmissions. This approach may be preferred if there are insufficient resources to multiplex WUS with SS/PBCH since SS/PBCH is multiplexed with SIB 1. Fig. 8 shows an example of multiplexing mode 2, with SCS of all signals being 120kHz. The multiplexing mode designates one symbol for the PDCCH, but WUS having one or two symbol durations may be frequency domain multiplexed with the PDCCH depending on the SCS configuration of the PDCCH and WUS. Fig. 8 shows an example with 2 beams.

WUS can also be frequency domain multiplexed with SIB1 or Type0 CSS and SIB 1. Fig. 9 shows an example of WUS frequency multiplexing with Type0 CSS and SIB1 for multiplexing mode 1, the search space starting from slot 2. For clarity, only 2 beams are shown.

As with the examples above, the definition of the time offset will depend on the WUS multiplexing scheme employed. In this example, the time offset is the duration between the PO and Type0 CSS/SIB1 occasions, and the associated WUS is multiplexed with the PO and Type0 CSS/SIB 1.

In the discussion above, the WUS is the same for each beam. However, the WUS may be beam specific such that the signal indicates the beam on which it is transmitted. That is, the WUS may encode the beam index. This allows the UE to determine which beams have the best reception from the detection of the WUS and thus may optimize SS/PBCH detection from the best received beam.

The use of beam-specific WUS does require the UE to monitor multiple WUS, e.g. up to 64, thus increasing complexity. However, this may be optimized, for example, by utilizing a base sequence and beam-specific cyclic shifts. Alternatively, a different root of the Zadoff-Chu sequence may be used for each beam, or a beam index may be used to initialize the scrambling sequence for the WUS.

The Group WUS (GWUS) may be used to reduce unnecessary wake-up of UEs to share the POs with the UEs being paged. It is currently proposed to support a maximum of 4 WUS resources, one of which spans 2 physical resource blocks (Physical Resource Block, PRBs) and W _max Subframes (this is the same as the previous WUS resource allocation). When using GWUS, if more than one group of UEs is sought The common WUS is sent to wake up UEs in all groups, but if only UEs in one group are paged, the group-specific GWUS (group-specific GWUS) is sent. To provide efficient operation, UEs should be assigned to groups (and thus GWUS resources) according to their likelihood of being paged. If UEs with high probability of being paged are placed in different groups, the probability of multiple groups being paged is higher, so the common WUS needs to be sent to wake up all UEs.

WUS resource multiplexing in E-UTRA is proposed as an implicit way, depending on whether R15 WUS is configured. If R15 WUS is not configured, 1 bit is used to indicate the location of the WUS resource and 2 bits are used to select the WUS resource configuration ID from the first four resource configurations. The location of the WUS resource is n0 or n2. Fig. 10 shows the 4 possible configurations described above if R15 WUS is not configured and the frequency location of WUS resource 0 is configured as n 0.

Each UE monitors WUS for shared WUS and GWUS in a single WUS resource. The GWUS is obtained by calculating the cyclic shift (g) of the base sequence:

wherein the method comprises the steps of

Is the UE group ID determined by an upper layer. As in R15, the scrambling sequence is initialized according to the associated PO and the cell ID, and the GWUS initialization is dependent on the WUS resource ID

Said traditional R15WUS is always identical to +.>

In association, the same sequence is used in R15.

Each WUS resource m=0, 1, …, M-1 can be configured with a different size (supporting 1,2,4, 8) by the upper layer parameter gWUS-numferroups-DRX. WUS group alternation may be activated in a GWUS configuration by GWUS-GroupAfiltration-r 16. The WUS resources are changed according to various parameters (e.g., SFN, PO). For example, the group in WUS0 is changed to use WUS1.

In NR, for UEs in rrc_idle/INACTIVE, a PDCCH-based wake-up signal is not desirable, because the required decoding requires a lot of power. A sequence-based wake-up signal may be required. The WUS is likely to be mainly used for power saving (e.g. REDCAP, reduced coverage) of low power UEs and thus the wake-up signal has to be robustly detected. In NB-IoT and MTC, this is achieved by using a configurable number of repetitions within the limited bandwidth. However, in NR, even more bandwidth is available for UEs of reduced performance (e.g. refcap) (e.g. 20MHz in FR 1). Increased flexibility for achieving robust detection may thus be obtained, which may be particularly beneficial for beam-based systems where the transmission time on each beam is limited. Listed below are various techniques for implementing an efficient and reliable wake-up system using frequency diversity and/or multiplexing.

In contrast to 1.4MHz (6 PRBs) in MTC and NB-IoT, a REDCAP NR device may support a bandwidth of at least 20MHz in FR1 and 50 to 100MHz in FR 2. For example, TS38.101 (Table 5.3.2-1) specifies 106 PRBs for the SCS at 15kHz for FR 120 MHz, where the maximum transmission bandwidth in FR1 is 100MHz, and there are 273 PRBs. For FR2, 50Mhz and 100MHz are considered to correspond to 32 and 66 PRBs of 120kHzS CS. Thus, more frequency resources may be available for WUS transmission. Thus, longer WUS sequences or WUS repetitions in the frequency domain may be utilized instead of time domain repetitions.

In comparison, in LTE-MTC WUS is transmitted on 2 consecutive PRBs, with a duration of at most a few subframes and granularity of one subframe (1 ms).

WUS resources refer to time-frequency resources that transmit one or more WUS sequences. For example, in LTE, WUS may be transmitted over the duration of M subframes on frequency resource n0, which is the first 2 PRBs. The WUS signal itself (i.e. the cyclic shift) depends on which group the UE belongs to. Furthermore, in LTE-MTC as described above, up to 4 WUS resources may be configured, each supporting a different number of groups.

Fig. 11 shows examples of different possible time-frequency resource allocations for WUS. Here, "WUS 0" spans 2 PRBs and 11 symbols, which is the same as LTE-MTC with a length 132 sequence. A different configuration of the same resource is shown as "WUS 1", where 11 PRBs and 2 symbols are allocated to the WUS. For frequency efficient multiplexing with the SS/PBCH block, "WUS 2" may accommodate a sequence of length 144 spanning 3 PRBs and 4 symbols.

In LTE-MTC, the frequency resources of the WUS are fixed to 1 PRB and 1 repetition in the adjacent PRB, i.e. 2 PRBs. However, the repetition in the time domain is configurable and depends on the repetition configured for the control channel MPDCCH (i.e., MTC PDCCH). In NR, since the beam-based operation requires a short transmission per beam, it is impossible to configure many repetitions in the time domain. On the other hand, in NR there are more available frequency resources than in LTE-MTC, e.g. 106PRB for 20MHz@15kHz SCS. Thus, the repetition in the frequency domain is configurable in addition to the time domain repetition.

In addition to repetition being configurable, the number and location of time-frequency of WUS resources is also configurable.

In an example, WUS may have a sequence length of 144 spanning 4 symbols and 3 PRBs. The sequence may be repeated N times in frequency and/or M times in the time domain. M and N are both configurable, and may depend on the configuration of the PDCCH or may be independent of the PDCCH.

Fig. 12 shows a set of examples of WUS resources that may be configured according to the principles discussed herein. WUS 0 spans 2 PRBs and 11 symbols and is repeated 3 times in the frequency domain. Therefore, the UE must monitor 6 PRBs and 11 symbols for the WUS. WUS 1 is repeated 2 times in the time domain, spanning a total of 4 symbols. WUS 3 shows a combination of time and frequency repetition, which is repeated 2 times in the frequency and time domain.

Table 8 below shows example WUS configuration parameters. The lack of a possibility of a parameter indicates no repetition.

TABLE 8

In LTE-MTC GWUS, each WUS resource is associated with a configured number of groups, e.g. WUS resource 1 supports 4 groups and WUS resource 3 supports 8 groups. Within each WUS resource, the groups are distinguished by different cyclic shifts of the underlying WUS sequence. All WUS have the same time-frequency allocation and therefore the same detection performance. However, in NR, which may be repeated in a frequency domain configuration, each WUS resource may have a different configurable number of repetitions. This allows multiple groups to be configured for REDCAP devices with more repetitions and multiple groups to be configured for other devices with fewer repetitions.

An example is shown in fig. 13, where 3 WUS resources are configured and the basic WUS sequence spans 3 PRBs and 4 symbols. WUS resource 0 (WUS 0) has no repetition, WUS 2 has 1 repetition in the frequency domain and WUS 2 has 2 repetitions in both the frequency domain and the time domain. Thus, a UE with poor coverage may be allocated to WUS resource 2, while a UE with good coverage is allocated to WUS resource 0. This flexible WUS resource allocation allows for maximization of spectrum utilization.

In LTE-MTC, the 4 WUS resources may be multiplexed in a 2-frequency division multiplexing (frequency divisio n multiplex, FDM) 2-time division multiplexing (time division multiplex, TDM) (i.e., 2-FDM 2-TDM) manner. However, more frequency resources are available in NR and 4 WUS resources can be fully multiplexed in the frequency domain. The 3-FDM mode has been proposed in LTE-MTC.

The flexibly configured signaling may be implemented by an ordered list having a size of the number of WUS resources configured, wherein the first entry corresponds to WUS resource 0, the second entry corresponds to WUS resource 1, etc. Examples are shown in table 9 below, where the frequency/time repetition list WUS-resourceRepetiti onFreqList/WUS-resourcerepetationtimelist is an ordered list that configures the number of repetitions for each WUS resource individually.

TABLE 9

Each UE need only monitor WUS in a single WUS resource. It is disclosed hereinafter that the location of the WUS resources is configurable. In LTER16, multiplexing of WUS resources is not so flexible in the case of GWUS (GWUS-only) alone, and only the frequency location of WUS resource 0 can be configured by gwUS-FreqLocati on-r 16= { n0, n2} as shown in FIG. 10. NR allows more flexibility in the frequency domain because more bandwidth is available. Thus different WUS resource patterns are disclosed that allow for being configurable in time-frequency.

Fig. 14 shows an example of a possible resource pattern of up to 4 WUS resources (4 WUS are used as an example only, other numbers may be used). The numbers of WUS resources described above are merely illustrative. Furthermore, each WUS resource is described as having the same size but may actually comprise a different number of time-frequency resources. Mode 0 in fig. 14 was agreed in LTE-MTC for GWUS without legacy R15 WUS. In resource mode 1, all WUS resources are multiplexed consecutively in the frequency domain, while in mode 2 they are spaced apart discontinuously to exploit frequency diversity and to make room for interleaving the same modes with different frequency offsets. Mode 3 and mode 4 multiplex WUS resources in time and frequency and are available for alternate use between them (as discussed in more detail below). Furthermore, modes 3 and 4 may also be spaced apart in frequency as in mode 2, but this is not shown in fig. 14.

The availability of WUS resource patterns allows for greater flexibility in resource management at the base station. The configurable frequency offset, which may be indicated as a parameter of the first WUS resource (WUS 0), allows defining orthogonal modes that do not interfere with each other. For example, pattern 2 in fig. 14 may be configured with 2 different frequency offsets to provide two WUS resource allocations that are orthogonal in the frequency domain. Thus, the same pattern with different frequency offsets may be configured in, for example, two neighboring cells to reduce the likelihood of the inter-cell interference (inter-cell interference) between their WUS sequences. Similarly, modes 3 and 4 can be used for two near end/neighbor cells because the modes are orthogonal.

The configuration of the base station may thus define the resource modes available for WUS signals and allow configuration of which modes to use.

For the purpose of multiplexing the WUS resources with other signals such as SS/PBCH, common search space 0 (CSS 0) or SIB1, a specific pattern in time/frequency resources may be defined. Fig. 15 shows an example of two WUS resource patterns multiplexed around the SS/PBCH transmission. The WUS resources are aligned such that WUS resources 0 and 1 within each mode are adjacent to SS/PBCH such that they have no gap with SS/PBCH if only 1 or 2 WUS are configured. The arrangement of the patterns with contiguous resources on opposite sides of the SS/PBCH resources maximizes frequency diversity.

Another mechanism to multiplex WUS resources around other signals is to bundle two or more modes in a defined pattern. For example, in fig. 15, mode 1 may be configured as two modes, one using WUS resources 0 and 2 and the other using WUS resources 1 and 3. For each mode frequency offset, they are then located at the SS/PBCH resources. The two modes may be different or the same, but with different frequency offsets. This definition method allows for more flexible multiplexing around other transmissions without defining a wide range of modes. By specifying which modes are bundles, the bundles may be indicated in a configuration message. After binding is enabled, the number of WUS resources will be applied to the bundled WUS resources.

The configuration may also enable the UE to switch between a configurable number of WUS multiplexing modes. In LTE GWUS, group alternate use allows for hopping/alternating between groups configured for one WUS resource and groups configured for another WUS resource. This configuration allows additional time/frequency diversity, but assuming that all WUS resources are configured with the same amount of resources, otherwise the detection performance may be different. The mode alternation discussed below may allow more frequency diversity without resource fragmentation and may support WUS resources with different resource configurations to ensure that UEs with reduced coverage are allocated to WUS resources with more resources.

Fig. 16 shows an example of three WUS resource patterns. Group alternation may be used in one mode to replace resources. For example, if groups alternate for mode 2 activation, WUS resource 0 may switch with WUS resource 3 to provide frequency diversity. In this example, the WUS resources are fragmented, so it is difficult for the base station to schedule other transmissions in the gap between the WUS resources.

Mode alternation may be implemented wherein the base station alternates between two or more WUS modes, e.g. mode 0 and mode 1. This provides frequency diversity but ensures that the WUS resources in each transmission are concentrated in one continuous time period/frequency resource, thereby improving the availability of the resources for use by other transmissions. The alternation may be configured using upper layer (RRC) signaling.

If an orthogonal mode is selected for the neighboring cells, care may be taken to ensure that enabling the alternation does not reduce the orthogonality and cause performance problems. The selection of the above-described resource modes may depend on: -

Paging occasions-e.g. alternating between a number of POs or cycling through all configured modes.

A preconfigured alternating period or pattern-for example alternating pattern every 2 POs, or alternating according to pattern (for example-pattern 0, pattern 1, pattern 0).

The system frame number of the PO or paging frame-e.g. if (SFN mod x) =0, mode 0 is used, and if (SFN mod y) =0, mode 1 is used.

A reference point may be defined, for example SFN0 may be used.

The length 132 LTE-MTC sequence spans 12 subcarriers and 11 symbols. In NR, the WUS sequence of 11 symbols may be too long to accommodate the time available on the beam in a beam switching system that has only a short transmission time for a cell-wide signal (e.g., WUS). To ensure transmission of the LTE-MTC sequence should be reduced to 1 symbol and thus extended to 132 subcarriers (11 PRBs). The repetition of the time and frequency is configurable by the time. Alternatively, the same design principle (single base sequence with different cyclic shifts and one orthogonal cover code) may be used, but with different lengths to suit the time available for transmission on the beams in NR. For example, the sequence may be a multiple of 4 symbols and 12 PRBs for efficient multiplexing with SS/PBCH.

In a particular example, the following functions may be added: -

Coverage codes for multiple frequency repetitions: the cover code is allowed to spread over multiple frequency repetitions of the base sequence (additional to the time domain). This will improve the randomization of interference between different sequences due to longer coverage codes, which is especially beneficial when configuring only repetitions in the time domain.

Improved cyclic shift: since coexistence with the previous version of WUS is not required, the cyclic shift can be used more efficiently by maximizing the distance between the shifts.

Beam-specific WUS: in the case of beam-specific WUS, the beam index is used to initialize the scrambling sequence to reduce interference between beams.

Let x=0, 1, …, m·k-1.M is the number of repetitions in the time domain and K is the number of repetitions in the frequency domain to which a unique WUS sequence is assigned. In the example where 4 repetitions are defined in the frequency domain, the same sequence is transmitted every repetition if k=1, and the unique coverage code is extended to 2 repetitions if k=2, so only 2 unique WUSs are transmitted in 4 repetitions. The parameter K is configurable, for example using upper layer (RRC) signaling.

The WUS sequence w (m) of length N is defined as: -

Wherein the method comprises the steps of

m＝0,1,...,N-1 (5)

m′＝m+Nx (6)

n＝m mod N (7)

The above-mentioned cover code theta _nfns (m') is defined as: -

Wherein the scrambling sequence c is given in section 5.2.1 of TS 38.211 _nfns (i) At i=0, 1, …,2·nm-1, and should be initialized at the beginning of the WUS as follows: -

Wherein n is _f And respectively n _s Is a first frame of a first PO and a first time slot of the first PO associated with the WUS. In addition, N _beam Is the beam index over which the WUS is to be transmitted.

The generic WUS sequence is g=0 and for

Each of which is->

Number of groups supported by WUS resources.

For beam-specific WUS, the scrambling sequence is indexed by the beam index N as shown in equation (10) above _beam Initializing.

Assigning the result sequence w of length N (M.K-1) to the WUS resources in a time-preferred or frequency-preferred manner

Within the first K repeated resource elements (KL). The sequence is repeated in the next K repetitions until all repetitions are filled. Said WUS resource->

Is signaled by the upper layer (RRC).

Although not shown in detail, any of the apparatus or devices forming part of the network may comprise at least a processor, a storage unit and a communication interface configured to perform the methods of any aspect of the invention. Further options and selections are described below.

The embodiments of the invention, in particular the signal processing functions of the gNB and the UE, may be implemented using a computing system or architecture known to those skilled in the relevant art. Computing systems may be used, such as desktop, laptop or notebook computers, hand-held computing devices (PDAs, cell phones, palm top computers, etc.), mainframes, servers, clients, or any other type of special or general purpose computing device as desired or appropriate for a given application or environment. The computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computing system may also include a main memory, such as random access memory (random acce ss memory, RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. Such main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may also include read only memory (read only memo ry, ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a Compact Disc (CD) or digital video Disc (Digital Video Disc, DVD) (RTM) drive to read from or write to a drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by a media drive. The storage medium may include a computer-readable storage medium storing specific computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, removable storage units and interfaces such as program cartridge and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

The computing system may also include a communication interface. Such a communication interface may be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other network interface controller (Network Interface Control ler, NIC) cards), communication ports (e.g., universal serial bus (Universal Serial Bus, US B) ports), personal computer memory card international association (Personal Computer Memory Card Int ernational Association, PCMCIA) slots and cards, and the like. The software and data transferred via the communications interface are in the form of signals described above and may be electronic, electromagnetic, optical or other signals capable of being received by the communications interface medium.

In this document, the terms "computer program product," "computer-readable medium," and the like may be used to generally refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by the processor(s) making up the computer system to cause the processor(s) to perform specified operations. Such instructions, generally 45, are referred to as "computer program code" (which may be grouped in computer program groupings or in other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause the processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., software libraries for performing standard functions) to do so.

The non-transitory computer readable medium may include at least one from the group consisting of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory (Erasable Programmable Read Only Mem ory, EPROM), electrically erasable programmable read-only memory, and flash memory. In embodiments where the elements are implemented using software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. A control module (in this example, software instructions or executable computer program code) when executed by the processor in the computer system causes the processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept may be applied to any circuit for performing signal processing functions within a network element. It is further contemplated that, for example, a semiconductor manufacturer may employ the inventive concepts described herein in the design of a stand-alone device, such as a microcontroller or application-specific integrated circuit (ASI C) of a digital signal processor (digital signal processor, DSP) and/or any other subsystem element.

It should be appreciated that for clarity, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by a plurality of different functional units and processors to provide the signal processing functions. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices.

Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. In addition, although individual features may be included in different claims, these may possibly be combined to advantage, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed, and in particular the order of individual steps in a method claim does not imply that the step commands must be performed in the method. Instead, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a," "an," "the first," "the second," etc. do not exclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Instead, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements as mentioned.

Claims (23)

1. A method of transmitting a wake-up signal from a base station to a User Equipment (UE) in a cellular communication system, the base station transmitting a plurality of beams, the method comprising:

A burst of wake-up signals is transmitted, the burst comprising at least one wake-up signal transmitted on each beam, wherein the burst of wake-up signals is arranged not to be transmitted during a control transmission (control transmi ssion).

2. The method of claim 1, wherein the wake-up signal burst is transmitted a predefined time offset before a paging occasion associated with the wake-up signal burst.

3. The method of claim 2, wherein the time offset is defined as a time from an end of the wake-up signal burst to a beginning of the paging occasion.

4. A method according to any preceding claim, characterized in that wake-up signals on at least two beams are transmitted in a set of adjacent symbols.

5. The method of claim 4, wherein the set of adjacent symbols spans a handoff between beams.

6. A method as claimed in any preceding claim, wherein the burst spans at least two time slots.

7. The method of any preceding claim, wherein the wake-up signal is frequency domain multiplexed with a synchronization signal (synchronization signal, SS)/physical broadcast channel (Physical Broadcast Channe l, PBCH), system information block SIB1, or physical downlink control channel (Physical Downlink Contr ol Channel, PDCCH) signal.

8. The method of claim 7, wherein the multiplexing configuration is defined by upper layer signaling.

9. The method according to claim 7, characterized in that the length of said at least one wake-up signal on one beam is the same as the length of said signal multiplexed therewith.

10. The method according to any of the preceding claims, characterized in that said at least one wake-up signal on at least two of said beams is identical.

11. The method according to any of the preceding claims, characterized in that the at least one wake-up signal on each beam is different.

12. The method according to any preceding claim, characterized in that the at least one wake-up signal on each beam comprises a base sequence with a cyclic shift depending on the beam.

13. The method according to any of claims 1 to 11, characterized in that the at least one wake-up signal on each beam utilizes a different root of a Zadoff-Chu sequence.

14. The method according to any of the preceding claims, characterized in that the length of the at least one wake-up signal on each beam is between 1 and 4 symbols.

15. The method according to any preceding claim, characterized in that the at least one wake-up signal on each beam is repeated.

16. The method according to any of the preceding claims, characterized in that the starting position of the wake-up signal burst is signalled to the user equipment UE in upper layer signalling.

17. The method according to any preceding claim, characterized in that a synchronization signal block (synchr onization signal block, SSB) occasion occurs between the at least one wake-up signal on one beam and the paging occasion to which the wake-up signal relates.

18. The method according to any of the preceding claims, characterized in that at least one wake-up signal is a group wake-up signal.

19. The method according to any of the preceding claims, characterized in that at least one wake-up signal is a common wake-up signal for all user equipments, UEs.

20. The method of claim 18, wherein the group wake-up signal is calculated as:

is defined by a cyclic shift g of a base sequence of (2), wherein

Is the group identifier ID determined by the upper layer protocol.

21. The method of any preceding claim, wherein the wake-up signal is sequence-based.

22. The method of any preceding claim, further comprising selecting a time-frequency transmission mode for the wake-up signal and indicating the mode to a plurality of user equipments, UEs.

23. A base station configured to perform the method of any of the preceding claims.

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