User equipment, network entity, telecommunications network and associated methods

Abstract

A user equipment (UE) (301) is configured to communicate using a plurality of radio access networks (RANs). The UE (301) comprises a plurality of primary communication units (303), (304) each configured to communicate over a respective RAN of the plurality of RANs and a secondary communication unit (302) in communication with each of the plurality of primary communication units (303), (304) and configured to draw less power than each of the plurality of primary communication units (303), (304). The secondary communication unit (302) is further configured to: receive a wake-up signal; and in response to receiving the wake-up signal, cause at least one of the plurality of primary communication units (303), (304) to transition from a relatively low power consumption mode to a relatively high power consumption mode.

Description

[0001] User Equipment, Network Entity, Telecommunications Network and Associated Methods

[0002] Field

[0003] The present disclosure relates to a user equipment (UE), a network entity and a telecommunications network. The present also relates to methods performed by the UE and network entity, as well as to computer programs and computer-readable media.

[0004] Background

[0005] The battery life of a mobile device or user equipment (UE) is an important consideration in all telecommunication systems (and especially those defined by the Third Generation Partnership Project, 3GPP, for instance 5G), along with throughput, latency, and reliability. The set of possible use cases for a particular device is affected by the length of its battery life, and therefore several efforts have been undertaken in order to achieve a higher energy efficiency or reduced battery consumption of UEs in 5G. An example is the work under the Study Item TR 38.840 in Rel-16 (Release 16), which led to the adoption of a multitude of techniques to reduce the UE power consumption, followed by the work item RP-221543 that introduced further techniques.

[0006] In both Release 16 and 17, it was recognized that one of the procedures that consumes a substantial amount of power in a UE is the paging procedure. This is because the UE needs to be configured with a given length of wake-up-periods (DRX, or discontinuous reception, cycle) to be able to monitor a Paging Occasion (PO). This DRX cycle can be extended to allow the UE to sleep during longer periods of time; however, this will lead to increased latency, which may not be suitable for certain use cases.

[0007] In periods where there is no signalling or data traffic, the UE will still need to periodically wake up once per DRX cycle, perform coarse synchronization by measuring the synchronization block, to successfully be able to receive a paging message, regardless of if it was sent by the network or not. This can be seen in Figure 1 (a) for Rel-15 / Rel-16 paging reception, which shows power consumption in the idle / inactive mode. Figure 1 is reproduced from https: / / www.mediatek.com / blog / new-whitepaper-5g-nr-power-saving-enhancements- in-release-17. For Rel-17, as shown in Figure 1 (b), a new behaviour was introduced. Figure 1 (b) shows that a Paging Early Indication (PEI) can be provided to indicate that the UE is not going to be paged. Here, the gNB or the core network would indicate to the UE whether to monitor a PO or not, in a sense to indicate if the UE is going to be paged. In the case in which a UE is indicated not to monitor the Paging Occasion, the UE will go to a sleep mode and reduce its power consumption.

[0008] In Rel-18, a new approach is being investigated, which involves employing a new low- powered receiver in the UE, separate from the main radio receiver, that would in turn wake up the main receiver whenever it is triggered, e.g. if the UE is paged. This Low-Power Wake Up Receiver (LP-WUR) would monitor an ultra-low power Wake-Up-Signal (LP-WUS) sent by the gNB, that would indicate whether to wake up the main receiver (MR) or to allow it to be in a deeper sleep mode if not triggered. Figure 2 is extracted from RWS-210168 and shows an example a general architecture of this approach.

[0009] While these existing approaches are satisfactory in some respects, there remains a need to improve battery life while maintaining and / or improving system performance.

[0010] Summary

[0011] Against this background, the present disclosure provides a user equipment according to claim 1 , a network entity according to claim 1 1 , a telecommunications network according to claim 28, a method according to claim 29, a method according to claim 30, a computer program according to claim 31 and a computer-readable medium according to claim 32.

[0012] As noted above, RWS-210168 describes a system in which each radio has a dedicated ultralow power wake-up receiver. Each radio can be woken up separately and paged separately. Some embodiments of the disclosure recognise that a single low power wake-up receiver could be used to wake up multiple radios, which can reduce the space required in a UE and provide more efficient waking up of the radios. Difficulties would occur if the radios were woken up at times at which no paging is taking place, so the disclosure proposes adaptations on the UE and on the network side to improve the timing of paging occasions of the different radio access networks (RANs), which are typically cellular networks. By doing so, a single wake-up signal can wake up two different radios at a mutually convenient point in time. In a first aspect, a user equipment (UE) is configured to communicate using a plurality of radio access networks (RANs), comprising: a plurality of primary communication units each configured to communicate over a respective RAN of the plurality of RANs; and a secondary communication unit in communication with each of the plurality of primary communication units and configured to draw less power than each of the plurality of primary communication units, the secondary communication unit further configured to: receive a wake-up signal; and in response to receiving the wake-up signal, cause at least one of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode.

[0013] Also provided is a method for configuring a user equipment (UE) to communicate using a plurality of radio access networks (RANs), the UE comprising a plurality of primary communication units each configured to communicate over a respective RAN of the plurality of RANs and a secondary communication unit in communication with each of the plurality of primary communication units and configured to draw less power than each of the plurality of primary communication units, the method comprising: receiving, by the secondary communication unit, a wake-up signal; and in response to receiving the wake-up signal, causing, by the secondary communication unit, at least one of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode.

[0014] The primary communication units may be conventional communication units. For example, they may be bi-directional communication units for communicating over various RANs. The secondary communication units described herein may be low-power receivers. For example, they may be configured solely for receiving wake-up signals and may be incapable of communicating over other protocols. This may allow the secondary communication units of the present disclosure to draw much less power than the primary communication units.

[0015] Therefore, by providing a single UE with a secondary communication unit that can wake up multiple primary communication units, a more efficient and effective way of communicating can be provided. The present disclosure provides a way to reduce the number of communications and modems needed and can ensure that UEs are able to communicate at appropriate times (e.g. when a paging message is expected). The present disclosure also provides a network entity for configuring communication of a user equipment (UE) with a plurality of radio access network (RANs), the network entity configured to: determine a plurality of paging occasions, the plurality of paging occasions comprising a respective paging occasion for each of the plurality of RANs; establish a time at which to send a wake-up signal to the UE based on the plurality of paging occasions; and send, to the UE and at the established time, the wake-up signal such that the UE will be configured to receive a paging message at the plurality of paging occasions over at least one of the plurality of RANs.

[0016] Also provided is a method for configuring communication of a user equipment (UE) with a plurality of radio access network (RANs), the method comprising: determining a plurality of paging occasions, the plurality of paging occasions comprising a respective paging occasion for each of the plurality of RANs; establishing a time at which to send a wake-up signal to the UE based on the plurality of paging occasions; and sending, to the UE and at the established time, the wake-up signal such that the UE will be configured to receive a paging message at the plurality of paging occasions over at least one of the plurality of RANs.

[0017] By configuring a UE in this way, it can be ensured that the UE will be able to receive paging messages at an appropriate time, even if the UE is in a low power mode for most of the time. The time at which a wake-up signal should be sent can be established using the knowledge the determined paging occasions for the plurality of RANs. Then, the wake-up signal can be sent at an appropriate time relative to the paging occasion. Such a wake-up signal could be used by a single wake-up receiver of the UE, and so this aspect may be complementary to and may work in tandem with the above-described aspects relating to the operation of a UE. A telecommunications network comprising the network entities and UEs described herein is therefore also provided.

[0018] Where the different radio access networks are synchronised, the plurality of paging occasions may be identical or may be set to be identical. In such cases, there may be provided a network entity for configuring communication of a user equipment (UE) with a plurality of radio access network (RANs), the network entity configured to: determine an aligned paging occasion for the plurality of RANs; establish a time at which to send a wakeup signal to the UE based on the aligned paging occasion; and send, to the UE and at the established time, the wake-up signal such that the UE will be configured to receive a paging message at the aligned paging occasion over at least one of the plurality of RANs. Listing of Figures

[0019] Embodiments of the present disclosure will be described by way of example with reference to the accompanying drawings, in which:

[0020] Figure 1 shows known wake-up procedures;

[0021] Figure 2 shows existing proposals for a Low-Power Wake Up Receiver (LP-WUR) to monitor an ultra-low power Wake-Up-Signal (LP-WUS);

[0022] Figure 3 shows a first embodiment of the present disclosure;

[0023] Figure 4 shows a timing relationship between a WUS and a PO;

[0024] Figure 5 shows a system incorporating embodiments of the present disclosure; and Figure 6 shows a system incorporating embodiments of the present disclosure.

[0025] Detailed Description

[0026] The architecture shown in Figure 2 focuses on a single modem 5G NR (New Radio) device. However, a typical device usually has one or more further modems, such as 4G Long Term Evolution (LTE), as seen Figure 3, for an EN-DC scenario (EN-DC being shorthand for E- UTRA-NR Dual Connectivity). Other combinations of communication protocols and modems can be provided, however. These may include other (3GPP-defined) cellular networks.

[0027] Figure 3 shows a single UE 301 at two points in time. The UE 301 comprises an ultra-low power wake-up receiver 302 and two Main Radios: an NR Main Radio 303 and an LTE Main Radio 304. The ultra-low power wake-up receiver 302 is coupled to and capable of communicating with and controlling the two Main Radios 303 and 304. On the left had side of Figure 3, the main radios 303 and 304 are in an off or deep sleep state. On the right hand side of Figure 3, the main radios 303 and 304 are in an on state.

[0028] In order to optimize battery usage (e.g. reduce battery usage) in such devices, embodiments of the present disclosure provide a way for a single LP-WUR to provide a wake-up message to multiple MRs (Main Radios) within a device, rather than to have more than one dedicated LP-WUR that each perform the same task for different MRs. Such an approach can provide more efficient power usage and can provide benefits in terms of the form factor of the device; a single LP-WUR to wake up multiple modems can provide a more efficient use of space within the device than having two LP-WURs (one for each modem). Accordingly, the embodiment of Figure 3 shows a first embodiment of the present disclosure. The first embodiment can be described in generalized terms as comprising a UE 301 configured to communicate using a plurality of RANs. In Figure 3, the RANs are 3GPP- defined cellular networks, specifically NR and LTE. The UE 301 comprises a plurality of primary communication units (the Main Radios 303 and 304) each configured to communicate over a respective RAN of the plurality of RANs. The UE 301 also comprises a secondary communication unit (the ultra-low power wake-up receiver 302) in communication with each of the plurality of primary communication units and configured to draw less power than each of the plurality of primary communication units. The secondary communication unit is further configured to receive a wake-up signal and, in response to receiving the wake-up signal, cause at least one of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode. In Figure 3, the relatively low power consumption mode is shown as being an OFF or deep sleep mode. The relatively high power consumption mode is an ON mode.

[0029] Stated differently, at least one of (and optionally each of) the plurality of primary communication units may be operable in a first power consumption mode and in a second power consumption mode, wherein the first power consumption mode is a lower power consumption mode than the second power consumption mode, and the secondary communication unit may be configured to receive a wake-up signal (e.g. a LP-WUS) and, in response to receiving the wake-up signal, cause at least one of (and optionally each of) the plurality of primary communication units to transition from its respective first power consumption mode to its respective second power consumption mode.

[0030] In some embodiments, and as defined in TR 38.869, the relatively low power consumption modes may be a state (e.g. a sleep state) that consumes approximately two orders of magnitude less power (a ratio of about 0.015 is defined in TR 38.869) than the relatively high power consumption mode (e.g. an active state of the main radio). Other ratios can be used while still providing the advantages noted herein. For example, in embodiments of the present disclosure, a ratio of power consumed in the relatively low power consumption mode to power consumed in the relatively high power consumption mode may be less than 0.1 , or less than 0.05, or less than 0.02, or less than 0.015, or less than 0.01. A secondary communication unit such as a low-power wake up receiver, when OFF, may consume 0.001 times as much power as when in an active mode; as noted in Table 6.3.2-1 of TR 38.869, the following values of relative power may be used for a LP-WUR: 0.01 / 0.05 / 0.1 / 0.5 / 1 / 2 / 4.

[0031] The secondary communication units described herein may be configured to cause, in response to receiving a single wake-up signal, each of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode. This can ensure that a plurality of primary communication units transition from a relatively low power consumption mode to a relatively high power consumption mode at an appropriate time, with only a single wake-up signal being needed. This can improve power consumption. The UEs described herein may comprise a power source (e.g. a single power source, such as a battery or cell), configured to provide power to each of the plurality of primary communication units and the secondary communication unit. The lifetime of such a power source can be extended using embodiments described herein.

[0032] The plurality of primary communication units can comprise various types of communication units. For example, the primary communications may comprise any one or more of: a modem; a bi-directional radio unit; and a main radio of the UE. These elements can all be controlled using the wake-up signals described herein.

[0033] The secondary communication units described herein may be configured to draw less power than the relatively low power consumption mode of at least one of, and preferably each of, the plurality of primary communication units. For example, the secondary communication units may use low-power communication protocols and / or methods relatively frequently. In contrast, the primary communication units may use relatively-high power communication protocols and / or methods less frequently, to reduce the total amount of power required. Accordingly, the secondary communication units described herein may comprise any one or more of: a low-power receiver; an ultra-low power receiver; a passive receiver; a wake-up receiver; and an almost-zero-power (AZP) receiver. The secondary communication units of the present disclosure may be configured to operate at the same frequency as one or more (or each) of the primary communication units; or in a different frequency band or frequency bandwidth part to one or more (or each) of the primary communication units.

[0034] The relatively high power consumption modes described herein may comprise an awake mode or a connected mode. The relatively low power consumption modes described herein may comprise any one or more of: an off mode; a deep sleep mode; an idle mode; and an inactive mode. Since the network entities and the UEs described herein can be adapted to various radio access technologies (such as cellular RATs), the specific power consumption modes may be different for such other RATs. The wake-up signals described herein may be received from various sources. For example, in embodiments of the present disclosure, a base station or a core network (CN) element can provide a wake-up signal to a UE.

[0035] The embodiment shown in Figure 3 can be configured so as to reduce power consumption compared to existing dual-modem (or multi-modem) devices. Some embodiments of the present disclosure provide further advantages by ensuring that paging occasions (POs) are aligned.

[0036] For example, the present disclosure provides, in addition to UEs of the type shown in Figure 3, a network entity for configuring communication of a UE with a plurality of radio access networks (RANs). The network entity is configured to determine a plurality of paging occasions, the plurality of paging occasions comprising a respective paging occasion for each of the plurality of RANs; establish a time at which to send a wake-up signal to the UE based on the plurality of paging occasions; and send, to the UE and at the established time, the wake-up signal such that the UE will be configured (by virtue of having received the wakeup signal at an appropriate time) to receive a paging message at the plurality of paging occasions (which could all coincide at a single instant in time) over at least one of (and optionally each of) the plurality of RANs. The network entity may be configured to page the UE over at least one of the plurality of RANs. For instance, the network entity may be a base station that performs the paging, but the paging could be performed by another network entity. In some embodiments, the determined paging occasion is the same for all of the RANs, i.e. the respective paging occasions may be an aligned paging occasion (e.g. when the RANs are synchronized). In other embodiments, the determined paging occasions may approximately coincide. In some embodiments, the paging occasions may coincide to within 1 radio frame. In some embodiments, the paging occasion may coincide to a few (e.g., 2, 3, 4 or 5) radio frames. Even with a small number of radio frames, a UE may only expect to be required for paging for a few milliseconds (noting a radio frame is 10ms).

[0037] In some embodiments, the network entity may be configured to determine the plurality of paging occasions by determining one or more configuration parameters for at least one of the plurality of RANs, such that at least one of the plurality of RANs sends a paging message at the plurality of paging occasions. If an entity other than the network entity performs this determination, then the plurality of paging occasions may be determined by determining one or more configuration parameters for at least one of the plurality of RANs, such that at least one of the plurality of RANs sends a paging message at the plurality of paging occasions. The output of such a determination could be fed to the network entity (or some other entity that performs paging). The network entity could be configured to cause the at least one of the plurality of RANs to operate with the determined one or more configuration parameters, for example by providing one or more calculation results to the core network to update the configuration parameters thereof.

[0038] The plurality of paging occasions may be determined based on any one or more of: a discontinuous reception (DRX) cycle of at least one of the plurality of RANs; and / or an identifier of the UE. The plurality of paging occasions may be determined based on an identifier of the UE. The identifier of the UE could the same for each of the plurality of RANs. For instance, the identifier of the UE could comprise a Temporary Mobile Subscriber Identity (TMSI). Various other parameters can be used in the determinations, but these parameters provide particular advantages.

[0039] The following presents a procedure for determining configuration parameters for at least one of the plurality of RANs, in a specific embodiment. A LP-WUS may be sent with a particular offset before a Paging Occasion (PO), and thus a means to optimize the POs in both an NR RAN and an LTE RAN can help to facilitate the embodiment shown in Figure 3. The paging occasion in both LTE and NR is given by an index that depends on the DRX cycle configured by the network, the UE identifier, amongst other parameters. The formulas for both LTE and NR can be found in TS 36.304 and TS 38.304 respectively, with the procedure being presented below:

[0040] If the UE supports E-UTRA connected to 5GC and NAS indicated to use 5GC for the selected cell:

[0041] UE ID -> 5G-S-TMSI mod 1024, if P-RNTI is monitored on Physical Downlink Control Channel (PDCCH).

[0042] UEJD -> 5G-S-TMSI mod 16384, if P-RNTI is monitored on NPDCCH (Narrowband PDCCH) or MPDCCH (MTC PDCCH, i.e. Machine Type Communication PDCCH).

[0043] This is same as UE ID used in NR: If the UE operates in eDRX

[0044] UEJD ->5G-S-TMSI mod 4096 else:

[0045] UE_ID->5G-S-TMSI mod 1024

[0046] At least for the E-UTRA connected to 5G core, the same UE ID is used in both networks when computing PO. Using the PO formulae, the network (which sends the WUS) can calculate the optimal time to send the WUS and hence optimize the UE power saving and operation.

[0047] The Formula to Calculate PO in E-UTRAN:

[0048] From TS 36.304, PF, PO, and PNB are determined by following formulae:

[0049] PF is given by following equation:

[0050] SFN mod T= (T div N)*(UE_ID mod N)

[0051] Index i s pointing to PO from subframe pattern defined in 7.2 will be derived from following calculation: i s = floor(UE_ID / N) mod Ns

[0052] If P-RNTI is monitored on MPDCCH, the PNB is determined by the following equation:

[0053] PNB = floor(UE_ID / (N*Ns)) mod Nn

[0054] If P-RNTI is monitored on NPDCCH and the UE supports paging on a non-anchor carrier, and if paging configuration for non-anchor carrier is provided in system information, then the paging carrier is determined by the paging carrier with smallest index n (0 < n < Nn-1 ) fulfilling the following equation: floor(UE_ID / (N*Ns)) mod W < W(0) + W(1 ) + ... + W(n)

[0055] System Information DRX parameters stored in the UE shall be updated locally in the UE whenever the DRX parameter values are changed in SI. If the UE has no IMSI, for instance when making an emergency call without USIM, the UE shall use as default identity UE ID = 0 in the PF, i s, and PNB formulas above. If the UE has no 5G-S-TMSI, for instance when the UE has not yet registered onto the network, the UE shall use as default identity UE ID = 0 in the PF and i_s formulas above.

[0056] The following Parameters are used for the calculation of the PF, i s, PNB, wg, and the NB- loT paging carrier:

[0057] - T: DRX cycle of the UE.

[0058] In RRCJDLE (Radio Resource Control idle mode) state:

[0059] - Except for NB-loT: If a UE specific extended DRX value of 512 radio frames is configured by upper layers according to 7.3, T =512. Otherwise, T is determined by the shortest of the UE specific DRX value, if allocated by upper layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by upper layers, the default value is applied.

[0060] In RRCJNACTIVE state, if extended DRX is not configured by upper layers as defined in 7.3:

[0061] - T is determined by the shortest of the RAN paging cycle, if configured, the UE specific paging cycle, if allocated by upper layers, and the default paging cycle.

[0062] In RRCJNACTIVE state if extended DRX is configured by upper layers according to 7.3:

[0063] - If a UE specific extended DRX value of 512 radio frames is configured, T is determined by the shortest of the RAN paging cycle, if configured, and 512 radio frames.

[0064] - If a UE specific extended DRX value other than 512 radio frames is configured:

[0065] - During the Paging Time Window (PTW), T is determined by the shortest of the RAN paging cycle, if configured, the UE specific paging cycle, if allocated by upper layers, and the default paging cycle. Outside the PTW, T is determined by the RAN paging cycle, if configured.

[0066] In RRCJNACTIVE state, if the UE supports inactiveStatePO-Determination and the network broadcasts ranPaginglnldlePO with value "true", the UE uses the T value applicable for RRCJDLE state for the determination of i_s. Otherwise, the UE uses the T value applicable for RRCJNACTIVE state.

[0067] In RRCJNACTIVE state, a BL UE or a UE in enhanced coverage uses the T value applicable for RRCJDLE state for the determination of PNB and i_s.

[0068] For NB-loT: If UE specific DRX value is allocated by upper layers and minimum UE specific DRX value is broadcast in system information, T = min (default DRX value, max (UE specific DRX value, minimum UE specific DRX value broadcast in system information)). If UE specific DRX is not configured by upper layers or if the minimum UE specific DRX value is not broadcast in system information, the default DRX value is applied.

[0069] - nB: 4T, 2T, T, T / 2, T / 4, T / 8, T / 16, T / 32, T / 64, T / 128, and T / 256, and for NB-loT also T / 512, and T / 1024.

[0070] - N: min(T,nB)

[0071] - Ns: max(1 ,nB / T)

[0072] - Nn: number of paging narrowbands (for P-RNTI monitored on MPDCCH) or paging carriers (for P-RNTI monitored on NPDCCH) determined as follows:

[0073] If UE monitors GWUS (Group Wake Up Signal) according to clause 7.5.1 : this is the number of paging narrowbands (paging carriers) that are configured with GWUS. else: this is the number of paging narrowbands (paging carriers) provided in system information.

[0074] - UEJD

[0075] If the UE supports E-UTRA connected to 5GC and NAS indicated to use 5GC for the selected cell:

[0076] 5G-S-TMSI mod 1024, if P-RNTI is monitored on PDCCH.

[0077] 5G-S-TMSI mod 16384, if P-RNTI is monitored on NPDCCH or MPDCCH. else IMSI mod 1024, if P-RNTI is monitored on PDCCH and Accepted IMSI Offset is not available.

[0078] Alternative IMSI mod 1024, if P-RNTI is monitored on PDCCH and Accepted IMSI Offset is available.

[0079] IMSI mod 4096, if P-RNTI is monitored on NPDCCH.

[0080] IMSI mod 16384, if P-RNTI is monitored on MPDCCH or if P-RNTI is monitored on NPDCCH and the UE supports paging on a non-anchor carrier, and if paging configuration for non-anchor carrier is provided in system information.

[0081] - W(i): Weight for NB-loT paging carrier i.

[0082] - W: Total weight of all NB-loT paging carriers, i.e. W = W(0) + W(1 ) + ... + W(Nn-1 ). If UE monitors GWUS according to clause 7.5.1 , Total weight of all NB-loT paging carriers configured with GWUS.

[0083] IMSI is given as sequence of digits of type Integer (i.e. integer values from 0 to 9), IMSI shall in the formulae above be interpreted as a decimal integer number, where the first digit given in the sequence represents the highest order digit.

[0084] For example:

[0085] IMSI = 12 (digit1 =1 , digit2=2)

[0086] In the calculations, this shall be interpreted as the decimal integer "12", not "1 x16+2 = 18". If an Accepted IMSI Offset is forwarded by upper layers, the UE shall use the Accepted IMSI Offset value and IMSI to calculate an Alternative IMSI value as defined in TS 23.401

[0023] .

[0087] 5G-S-TMSI is a 48 bit long bit string as defined in TS 23.501

[0039] . 5G-S-TMSI shall in the PF and i_s formulae above be interpreted as a binary number where the left most bit represents the most significant bit.

[0088] The formula to calculate PO in NR:

[0089] From TS 38.304, The PF and PO for paging are determined by the following formulae:

[0090] SFN for the PF is determined by: (SFN + PF offset) mod T = (T div N)*(UE_ID mod N)

[0091] Index (i s), indicating the index of the PO is determined by: i s = floor (UEJD / N) mod Ns

[0092] The PDCCH monitoring occasions for paging are determined according to pagingSearchSpace as specified in TS 38.213 [4] and firstPDCCH-MonitoringOccasionOfPO and nrofPDCCH-MonitoringOccasionPerSSB-InPO if configured as specified in TS 38.331 [3]. When SearchSpaceld = 0 is configured for pagingSearchSpace, the PDCCH monitoring occasions for paging are same as for RMSI as defined in clause 13 in TS 38.213 [4],

[0093] When SearchSpaceld = 0 is configured for pagingSearchSpace, Ns is either 1 or 2. For Ns = 1 , there is only one PO which starts from the first PDCCH monitoring occasion for paging in the PF. For Ns = 2, PO is either in the first half frame (i_s = 0) or the second half frame (i_s = 1 ) of the PF.

[0094] When SearchSpaceld other than 0 is configured for pagingSearchSpace, the UE monitors the (i_s + 1 )thPO. A PO is a set of 'S*X ' consecutive PDCCH monitoring occasions where 'S' is the number of actual transmitted SSBs determined according to ssb-PositionsInBurst in SIB1 and X is the nrofPDCCH-MonitoringOccasionPerSSB-InPO if configured or is equal to 1 otherwise. The [x*S+K]thPDCCH monitoring occasion for paging in the PO corresponds to the Kthtransmitted SSB, where x=0,1 ,...,X-1 , K=1 ,2,...,S. The PDCCH monitoring occasions for paging which do not overlap with UL symbols (determined according to tdd- UL-DL-ConfigurationCommori) are sequentially numbered from zero starting from the first PDCCH monitoring occasion for paging in the PF. When firstPDCCH- MonitoringOccasionOfPO is present, the starting PDCCH monitoring occasion number of (i_s + 1)thPO is the (i_s + 1 )thvalue of the firstPDCCH-MonitoringOccasionOfPO parameter; otherwise, it is equal to i_s * S*X. If X > 1 , when the UE detects a PDCCH transmission addressed to P-RNTI within its PO, the UE is not required to monitor the subsequent PDCCH monitoring occasions for this PO.

[0095] NOTE 1 : A PO associated with a PF may start in the PF or after the PF. NOTE 2: The PDCCH monitoring occasions for a PO can span multiple radio frames. When SearchSpaceld other than 0 is configured for paging-SearchSpace the PDCCH monitoring occasions for a PO can span multiple periods of the paging search space.

[0096] The following parameters are used for the calculation of PF and i_s above:

[0097] T: DRX cycle of the UE.

[0098] If the UE does not operate in eDRX as defined in clause 7.4:

[0099] - T is determined by the shortest of the UE specific DRX value(s), if configured by RRC and / or upper layers or provided in PC5-RRC signalling in case of a L2 U2N Relay UE, and a default DRX value broadcast in system information. In RRCJDLE state, if UE specific DRX is not configured by upper layers, the default value is applied.

[0100] In RRCJDLE state, if the UE operates in eDRX and eDRX is configured by upper layers, i.e., DRX. CN, according to clause 7.4:

[0101] - If TeDRx, CN is no longer than 1024 radio frames:

[0102] - T = TeDRX, CN !

[0103] - else:

[0104] - During CN configured PTW, T is determined by the shortest of UE specific DRX value, if configured by upper layers, and the default DRX value broadcast in system information.

[0105] In RRCJNACTIVE state, if the UE operates in eDRX and eDRX is configured by RRC, i.e., TeDRx, RAN , and / or upper layers, i.e., DRX. CN, as defined in clause 7.4:

[0106] - If both DRX, CN and used TeDRx, RAN are no longer than 1024 radio frames, T = min{TeDRx, RAN, T6DRX, CN}.

[0107] - If TeDRx, CN is no longer than 1024 radio frames and no TeDRx, RAN is configured or used, T is determined by the shortest of UE specific DRX value configured by RRC and TeDRx, CN.

[0108] If TeDRx, CN is longer than 1024 radio frames: If TeDRx, RAN is not configured or used:

[0109] - During CN configured PTW, T is determined by the shortest of the UE specific DRX value (s), if configured by RRC and / or upper layers, and a default DRX value broadcast in system information. Outside the CN configured PTW, T is determined by the UE specific DRX value configured by RRC;

[0110] - else if used TeDRx, RAN is no longer than 1024 radio frames:

[0111] - During CN configured PTW, T is determined by the shortest of the UE specific DRX value, if configured by upper layers and TeDRx, RAN, and a default DRX value broadcast in system information. Outside the CN configured PTW, T is determined by TeDRx, RAN.

[0112] N: number of total paging frames in T

[0113] Ns: number of paging occasions for a PF

[0114] PF offset: offset used for PF determination

[0115] UEJD:

[0116] If the UE operates in eDRX as specified in clause 7.4:

[0117] - 5G-S-TMSI mod 4096 else:

[0118] 5G-S-TMSI mod 1024

[0119] The value ranges for each parameter in PO calculations are below:

[0120] For E-UTRAN:

[0121] T: DRX cycle of the UE, T is determined by the shortest of the UE specific DRX value, if allocated by upper layers, and a default DRX value broadcast in system information.

[0122] T: rf32, rf64, rf128, rf256.

[0123] Additionally, eDRX can be applied rf1024. Different rules may be applied when using eDRX. However, for a WUS, eDRX may or may not be used, as using eDRX would add extra delay in waking up the UE, which could be contradictory to the purpose of providing a WUS. nB: 4T, 2T, T, T / 2, T / 4, T / 8, T / 16, T / 32, T / 64, T / 128, and T / 256, and for NB-loT also T / 512, and T / 1024. - N: min(T,nB)

[0124] - Ns: max(1 ,nB / T)

[0125] For NR:

[0126] T shortest of the UE specific DRX value(s), if configured by RRC and a default DRX value broadcast in system information.

[0127] T: rf32, rf64, rf128, rf256

[0128] Ns: number of paging occasions for a PF {4, 2, 1}

[0129] PF offset: offset used for PF determination (can be set to 0 to set alignment)

[0130] Table 1 shows default paging cycle, used to derive T in TS 38.304

[0020] . Value rf32 corresponds to 32 radio frames, value rf64 corresponds to 64 radio frames and so on.

[0131] When sending a WUS, the next PO may be considered and the WUS may be provided in advance, so that the MR can be switched on prior to the corresponding PO. Note that WUS and PO may be in different frequency bands or bandwidth parts.

[0132] Figure 4 shows a time domain illustration of a timing relationship between the WUS and the PO according to some embodiments of the disclosure. There may be a maximum possible duration of a WUS and the PO may be set some time after the WUS is guaranteed to have ended, as illustrated by the gap in Figure 4. This can ensure that the PO does not start too soon (e.g. before the WUS has successfully woken up all radios). Hence, in embodiments of the disclosure, the established time (i.e., the established time at which to send a wake-up signal to the UE) may precede the plurality of paging occasions (which may simply be an aligned paging occasion). The established time at which to send the wake-up signal may be determined by adding an offset (e.g. a temporal offset, or some index that can be converted into a temporal offset) to one or more of the plurality of paging occasions. By inspecting the above-described equations for both LTE and NR, the similarities for the calculation of the Paging Frame and Paging Occasion for both RATs (Radio Access Technologies) can be seen. The formulae from above are reproduced below for reference:

[0133] The formula to calculate PO in E-UTRAN:

[0134] From TS 36.304, PF, PO, and PNB are determined by following formulae:

[0135] PF is given by following equation:

[0136] SFN mod T= (T div N)*(UE_ID mod N)

[0137] Index i s pointing to PO from subframe pattern defined in 7.2 will be derived from following calculation: i s = floor(UE_ID / N) mod Ns

[0138] The formula to calculate PO in NR:

[0139] From TS 38.304, The PF and PO for paging are determined by the following formulae:

[0140] SFN for the PF is determined by:

[0141] (SFN + PF offset) mod T = (T div N)*(UE_ID mod N)

[0142] Index (i s), indicating the index of the PO is determined by: i s = floor (UEJD / N) mod Ns

[0143] When the 5GC (5G Core) allocates the same 5G-S-TMSI for both LTE and NR, one way to align the POs is to have the Paging Offset parameter of 5G as oneT in the nAndPagingFrameOffset IE, while keeping the same parameters equal in both NR and LTE. With this configuration, the equation for PF and PO calculation is the same for NR and LTE. The same reasoning applies when the non-NR modem is NB-loT and LTE-M, by referring to similar calculations in TS 36.304 as described above.

[0144] This paging alignment is an example of an optimal time to send LP-WUS when both LTE and NR networks are synchronized. With the LP-WUS signal, there can be in turn a 1 -bit indication of which modem to wake up, either LTE or NR in the examples shown herein. Hence, in generalized terms, the wake-up signals described herein may comprise an indication of a communication unit (or a plurality of communication units) of the UE to wake up. At least two RANs of the plurality of RANs may be associated with a common core network (e.g. a 5GC). In some embodiments, at least two RANs of the plurality of RANs are preferably synchronized with each other, but this is not essential. When the LTE and NR networks are not synchronized, then the procedures described above can still provide an estimate of a possible location of the LP-WUS signal.

[0145] When the 5GC allocates different TMSI values for LTE and NR, since these values are still known by the network, the gNB can still optimize for such an alignment to happen based on the same procedure as explained above. However, this approach may instead provide an estimate of the time at which to send the LP-WUS, rather than a perfect alignment of the POs.

[0146] For EN-DC scenarios, the LTE device is responsible for monitoring POs in idle mode, since the EN-DC is not visible in RRCJdle. Therefore, the UE paging would follow the same procedure as a UE camping on an LTE cell. Therefore, the NR-WUS signal may not be used to optimize the UE power for paging in LTE.

[0147] LTE also supports RRCJnactive using the same procedure as for NR, for example if the base station is connected to the 5GC. Even in this scenario, the UE only listens to the LTE for paging according to the current procedure.

[0148] Figure 5 shows a schematic diagram of a system 10 for implementing the above-described embodiments. The system 10 incorporates a UE 20 and a network entity 30 (which in this example is a gNB base station) connected to other parts of a telecommunications network 70. The system 10 may include a plurality of network entities 30 and many UEs 20, but Figure 6 only shows a single UE 20 and network entity 30 for simplicity.

[0149] A plurality of primary communication units 40 and a secondary communication unit 50 are shown within the UE 20. All communication units are shown as being connected to an antenna 90 of the UE, but there may be separate antennas and each communication unit may have its own antenna in certain alternative implementations. The network entity 30 has a processor 80 that controls how and when the signals are sent from the network entity 30 using its own antenna 85. Each primary communication unit 40 may include any type of processor 60 that contains logic to control the way in which the respective communication unit 40 operates. The processor 60 may comprise or be a modem. In Figure 5, communication over a plurality of RANs 45 is shown between the network entity 30 and the primary communication units 40 of the UE 20. A wake-up signal 55 is shown schematically also between the network entity 30 and the secondary communication unit 50. The secondary communication unit 50 is shown in communication with the primary communication units 40. In particular, when the secondary communication unit 50 receives the wake-up signal 55, the secondary communication unit 50 communicates with one or more of the primary communication units 40, which process a communication 25 received from the secondary communication unit 50. At least one of the primary communication units 40 changes its power consumption state from any low power modes (e.g. inactive or idle) to a high (or higher) power mode (e.g. active or connected), thereby allowing at least one of the primary communication units 40 to receive communications over one of the plurality of RANs 45 from the network entity 30.

[0150] Figure 6 shows an embodiment in which the paging procedure is enhanced for RRCJnactive UEs. In this embodiment, a UE was EN-DC configured prior to transition to the RRCJnactive mode. While in the RRCJnactive mode, the UE stores EN-DC configuration.

[0151] In this case, when transitioning to the RRCJnactive mode, the UE may be commanded to listen to the NR-WUS signal for paging optimisation. Then, the UE can listen to the NR-WUS signal for paging optimisation on LTE while in the RRCJnative.

[0152] There are two types of paging used in RRCJnactive: RAN paging and CN paging. CN paging is the same as the Idle mode paging where the paging message is originated from the core network. For RAN paging, the paging is originated from the RAN (e.g. a RAN anchor node). The NR-WUS signal based paging enhancements described herein can be enabled in both RAN and CN paging.

[0153] The above-described embodiments can be used in various scenarios. For example, the plurality of RANs of the UEs described herein may comprise any one or more of: Long-Term Evolution (LTE); New Radio (NR); Narrowband - Internet of Things (NB-loT); and Long-Term Evolution Machine Type Communication (LTE-M). The network entities may be a base station or a core network (CN) element. In some embodiments, the wake-up signals described herein may be a New Radio wake-up signal (NR-WUS). It will be appreciated that embodiments of the disclosure may be implemented using a variety of different information processing systems. In particular, although the Figures and the discussion thereof provide exemplary computing systems and methods, these are presented merely to provide a useful reference in discussing various aspects of the disclosure. Embodiments may be carried out on any suitable data processing device, such as a personal computer, laptop, tablet, personal digital assistant, mobile telephone, smart phone, set top box, television, server computer, etc. Of course, the description of the systems and methods has been simplified for purposes of discussion, and they are just one of many different types of systems and methods that may be used. It will be appreciated that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or elements, or may impose an alternate decomposition of functionality upon various logic blocks or elements.

[0154] It will be appreciated that the above-mentioned functionality may be implemented as one or more corresponding modules as hardware and / or software. For example, the above- mentioned functionality may be implemented as one or more software components for execution by a processor of the system. Alternatively, the above-mentioned functionality may be implemented as hardware, such as on one or more field-programmable-gate-arrays (FPGAs), and / or one or more application-specific-integrated-circuits (ASICs), and / or one or more digital-signal-processors (DSPs), and / or other hardware arrangements.

[0155] It will be appreciated that, insofar as embodiments of the disclosure are implemented by a computer program, then a storage medium and a transmission medium carrying the computer program form aspects of the disclosure. The computer program may have one or more program instructions, or program code, that, when executed by a computer, causes an embodiment of the disclosure to be carried out. The term “program” as used herein, may be a sequence of instructions designed for execution on a computer system, and may include a subroutine, a function, a procedure, a module, an object method, an object implementation, an executable application, an applet, a servlet, source code, object code, a shared library, a dynamic linked library, and / or other sequences of instructions designed for execution on a computer system. The storage medium may be a magnetic disc (such as a hard drive or a floppy disc), an optical disc (such as a CD-ROM, a DVD-ROM or a Blu-ray disc), or a memory (such as a ROM, a RAM, EEPROM, EPROM, Flash memory or a portable / removable memory device), etc.. The transmission medium may be a communications signal, a data broadcast, a communications link between two or more computers, etc.. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0156] As used herein, including in the claims, unless the context indicates otherwise, singular forms of the terms herein are to be construed as including the plural form and, where the context allows, vice versa. For instance, unless the context indicates otherwise, a singular reference herein including in the claims, such as “a” or “an” (such as a UE or a network entity) means “one or more” (for instance, one or more UEs, or one or more network entities). Throughout the description and claims of this disclosure, the words “comprise”, “including”, “having” and “contain” and variations of the words, for example “comprising” and “comprises” or similar, mean that the described feature includes the additional features that follow, and are not intended to (and do not) exclude the presence of other components.

[0157] The use of any and all examples, or exemplary language (“for instance”, “such as”, “for example” and like language) provided herein, is intended merely to better illustrate the disclosure and does not indicate a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0158] Any steps described in this specification may be performed in any order or simultaneously unless stated or the context requires otherwise. Moreover, where a step is described as being performed after a step, this does not preclude intervening steps being performed.

[0159] All of the aspects and / or features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. In particular, the preferred features of the disclosure are applicable to all aspects and embodiments of the disclosure and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination). A method of manufacturing and / or operating any of the devices disclosed herein is also provided. The method may comprise steps of providing each of the features disclosed and / or configuring or using the respective feature for its stated function.

Claims

Claims:1 . A user equipment (UE) configured to communicate using a plurality of radio access networks (RANs), comprising: a plurality of primary communication units each configured to communicate over a respective RAN of the plurality of RANs; and a secondary communication unit in communication with each of the plurality of primary communication units and configured to draw less power than each of the plurality of primary communication units, the secondary communication unit further configured to: receive a wake-up signal; and in response to receiving the wake-up signal, cause each of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode.

2. The UE of claim 1 , comprising a power source configured to provide power to each of the plurality of primary communication units and the secondary communication unit.

3. The UE of claim 1 or claim 2, wherein the plurality of primary communication units comprise any one or more of: a modem; a bi-directional radio unit; and a main radio of the UE.

4. The UE of any preceding claim, wherein the secondary communication unit is configured to draw less power than the relatively low power consumption mode of at least one of, and preferably each of, the plurality of primary communication units.

5. The UE of any preceding claim, wherein the secondary communication unit comprises any one or more of: a low-power receiver; an ultra-low power receiver; a passive receiver; a wake-up receiver; an almost-zero-power (AZP) receiver.

6. The UE of any preceding claim, wherein the relatively high power consumption mode is an awake mode or a connected mode.

7. The UE of any preceding claim, wherein the relatively low power consumption mode is any one or more of: an off mode; a deep sleep mode; an idle mode; and an inactive mode.

8. The UE of any preceding claim, wherein the wake-up signal is received from a base station or a core network (CN) element.

9. The UE of any preceding claim, wherein the secondary communication unit is configured to operate: at the same frequency as one or more of the primary communication units; or in a different frequency band or frequency bandwidth part to one or more of the primary communication units.

10. A telecommunications network, comprising: the UE of any of claims 1 to 9; and a network entity for configuring communication of the UE with the plurality of RANs, the network entity configured to: determine a plurality of paging occasions, the plurality of paging occasions comprising a respective paging occasion for each of the plurality of RANs; establish a time at which to send the wake-up signal to the UE based on the plurality of paging occasions; and send, to the UE and at the established time, the wake-up signal such that the UE will be configured to receive a paging message at the plurality of paging occasions over at least one of the plurality of RANs.1 1. The telecommunications network of claim 10, wherein the respective paging occasions are an aligned paging occasion.

12. The telecommunications network of claim 10 or claim 1 1 , wherein the network entity is configured to determine the plurality of paging occasions by determining one or more configuration parameters for at least one of the plurality of RANs, such that at least one of the plurality of RANs sends a paging message at the plurality of paging occasions.

13. The telecommunications network of claim 12, wherein the network entity is configured to cause the at least one of the plurality of RANs to operate with the determined one or more configuration parameters.

14. The telecommunications network of any of claims 10 to 13, wherein the network entity is configured to determine the plurality of paging occasions based on any one or more of: a discontinuous reception (DRX) cycle of at least one of the plurality of RANs; and / or an identifier of the UE.

15. The telecommunications network of any of claims 10 to 14, wherein the network entity is configured to determine the plurality of paging occasions based on an identifier of the UE, wherein the identifier of the UE is the same for each of the plurality of RANs.

16. The telecommunications network of any of claims 10 to 15, wherein the network entity is configured to determine the plurality of paging occasions based on an identifier of the UE, wherein the identifier of the UE comprises a Temporary Mobile Subscriber Identity (TMSI).

17. The telecommunications network of any of claims 10 to 16, wherein the wake-up signal comprises an indication of a communication unit of the UE to wake up.

18. The telecommunications network of any of claims 10 to 17, wherein the established time precedes the plurality of paging occasions.

19. The telecommunications network of any of claims 10 to 18, wherein the network entity is configured to establish the time at which to send the wake-up signal by adding an offset to one or more of the plurality of paging occasions.

20. The telecommunications network of any of claims 10 to 19, wherein the network entity is further configured to page the UE at the plurality of paging occasions.21 . The telecommunications network of any of claims 10 to claim 20, wherein the network entity is configured to page the UE over at least one of the plurality of RANs.

22. The telecommunications network of any of claims 10 to 21 , wherein at least two RANs of the plurality of RANs are associated with a common core network.

23. The telecommunications network of any of claims 10 to 22, wherein at least two RANs of the plurality of RANs are synchronized with each other.

24. The telecommunications network of any of claims 10 to 23, wherein the plurality of RANs comprises any one or more of: Long-Term Evolution (LTE); New Radio (NR); Narrowband - Internet of Things (NB-loT); and Long-Term Evolution Machine Type Communication (LTE-M).

25. The telecommunications network of any of claims 10 to 24, wherein the network entity is a base station or a core network (CN) element.

26. The telecommunications network of any of claims 10 to 25, wherein the wake-up signal is a New Radio wake-up signal (NR-WUS).

27. A method for configuring a user equipment (UE) to communicate using a plurality of radio access networks (RANs), the UE comprising a plurality of primary communication units each configured to communicate over a respective RAN of the plurality of RANs and a secondary communication unit in communication with each of the plurality of primary communication units and configured to draw less power than each of the plurality of primary communication units, the method comprising: receiving, by the secondary communication unit, a wake-up signal; and in response to receiving the wake-up signal, causing, by the secondary communication unit, each of the plurality of primary communication units to transition from a relatively low power consumption mode to a relatively high power consumption mode.

28. The method of claim 27, further comprising: determining a plurality of paging occasions, the plurality of paging occasions comprising a respective paging occasion for each of the plurality of RANs; establishing a time at which to send a wake-up signal to the UE based on the plurality of paging occasions; and sending, to the UE and at the established time, the wake-up signal such that the UE will be configured to receive a paging message at the plurality of paging occasions over at least one of the plurality of RANs.

29. A computer program comprising instructions configured to: cause a secondary communication unit of a UE to execute the steps of the method of claim 27.

30. A computer-readable medium having stored thereon the computer program of claim 29.

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