Paging early indication

Abstract

A mobile communication system configured to receive at a user equipment from a network; a paging early indication (PEI) specifying a number of paging occasions per PEI (po-NumPerPEI) 31. Receiving Dow

Description

Field Example embodiments may relate to user equipments, network nodes, methods and / or computer programs for use in mobile communication systems. More particularly, the example embodiments relate to Paging Early Indication. Background In 5G, paging is the mechanism by which the network alerts User Equipment (UE) about incoming data, messages, or calls when the device is in RRC idle or inactive mode and for limited purposes (e.g. indication of emergency situations) when the device is in RRC connected mode. This process enables UEs to stay in low-power states, waking only to monitor for relevant information from the network, thereby saving battery life. The paging cycle defines the interval at which the UE checks for paging messages, with longer cycles favoring energy savings and shorter cycles enabling faster notification. Within each cycle, specific Paging Frames (PF) are designated for potential paging messages to the UEs. To optimize this process further, 5G employs UE grouping, a method that organizes UEs into distinct groups based on their unique identifiers (UE IDs). This distribution spreads the paging load, preventing large numbers of UEs from being paged in a single occasion and thus attempting to access the network simultaneously. Based on the unique identifiers, each UE is assigned to a specific group with its designated PF and specific Paging Occasion (PO). Within these PF, each group listens for paging messages at its PO, allowing UEs to remain in low-power mode and wake up only as needed (to monitor for paging and when the UE is paged, in which case UE ID is listed in the paging record of the paging message). Additionally, 5G introduces a Paging Early Indication (PEI) concept, where an early signal notifies UEs about whether they should monitor an upcoming PO, allowing UE to monitor next PO only if there is a message, reducing the time they spend actively monitoring for a message. There remains a need for further improvement in PEI messaging for overall energy saving (UE energy saving, and / or network energy saving (NES)). Summary The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. According to a first aspect, there is provided a first apparatus in a mobile communications system comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI; receive, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus; determine whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions; if at least one of the one or more conditions are satisfied, determine the first at least one bit of the DCI based on the shifted starting bit position; and determine whether to monitor a paging occasion based, at least in part, on the first indication. In some examples, at least one of the one or more conditions are based on one or more of the po-NumPerPEI, a number of subgroups of user equipment (UE) associated with a paging occasion, a number of used bits in the DCI and / or a number of spare bits in the DCI. In some examples, at least one of the one or more conditions are satisfied if the po-NumPerPEI is less than or equal to a first threshold. In some examples, the first threshold is equal to four. In some examples, at least one of the one or more conditions is based on a product of the po-NumPerPEI and the number of subgroups of UE associated with a paging occasion. In some examples, at least one of the one or more conditions is based on a value of a number of paging occasions per paging frame (Ns). In some examples, at least one of the one or more conditions is satisfied if the value of the number of paging occasions per paging frame (Ns) is less than or equal to two. In some examples, at least one of the one or more conditions is based on a value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion. In some examples, at least one of the one or more conditions is satisfied if the value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion is less than or equal to four. In some examples, at least one of the one or more conditions is based on a product of a value of a number of paging occasions per paging frame (Ns) and a value of a sum of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion. In some examples, at least one of the one or more conditions is satisfied if the value of the product is less than or equal to sixteen. In some examples, at least one of the one or more conditions is satisfied if the number of spare bits in the DCI is greater than or equal to sixteen. In some examples, the one or more conditions are satisfied if a second indication is received from the second apparatus indicating to determine the first at least one bit based on the shifted starting bit position. In some examples, the instructions further cause the first apparatus to apply an offset value to the first starting bit position for determining the shifted starting bit position if one or more of conditions are satisfied. In some examples, the instructions further cause the first apparatus to receive the offset value from the second apparatus. In some examples, the instructions further cause the first apparatus to calculate the offset value based, at least in part, on a number of used bits in the DCI and / or a number of spare bits in the DCI. In some examples, the first apparatus calculates the offset value based on information comprised in a system information block (SIB), comprising one or more of a physical control channel configuration (PCCH-Config) information element, a number of subgroups per paging occasion, a number of subgroups per user equipment (UE) identity, and / or tracking reference signal availability indication. In some examples, the instructions further cause the first apparatus to calculate the number of used bits based on: k = ns * (subgroupsNumPerPO-rl7 + subgroupsNumForUEID-rl7) + (indBitID+\) where k=number of used bits ns= PCCH-Config information element; subgroupsNumPerPO-rl7 = number of subgroups per paging occasion; subgroupsNumForUEID-rl7 = number of subgroups per user equipment UE identity; and indBitID= tracking reference signal (TRS) availability indication. In some examples, the offset value is equal to k+1. In some examples, the instructions further cause the first apparatus to determine the shifted starting bit position to be based on a least significant bit of the DCI. In some examples, the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasion index of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI. In some examples, the shifted starting bit position is determined based on: maxDCI-2-7-Size-rl7 — (iP0 ■ K + iSG), where maxDCI-2-7-Size-rl7= total number of bits of the DCI; iP0 = paging occasion index of the UE; K = N$° the number of subgroups per PO; and iSG = subgroup index of the UE. In some examples, the first apparatus is a user equipment and the second apparatus is a base station (gNB) and / or a network node. In some examples, said determining whether to monitor a paging occasion is based on the first indication. According to a second aspect, this specification describes a method performed at a first apparatus in a mobile communications system comprising: receiving, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI; receiving, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus; determining whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions; determining the first at least one bit of the PEI message based on the shifted starting bit position; and determining whether to monitor a paging occasion based, at least in part, on the first indication. In some examples, at least one of the one or more conditions are based on one or more of the po-NumPerPEI, a number of subgroups of user equipment (UE) associated with a paging occasion, a number of used bits in the DCI and / or a number of spare bits in the DCI. In some examples, at least one of the one or more conditions are satisfied if the po-NumPerPEI is less than or equal to a first threshold. In some examples, the first threshold is equal to four. In some examples, at least one of the one or more conditions is based on a product of the po-NumPerPEI and the number of subgroups of UE associated with a paging occasion. In some examples, at least one of the one or more conditions is based on a value of a number of paging occasions per paging frame (Ns). In some examples, at least one of the one or more conditions is satisfied if the value of the number of paging occasions per paging frame (Ns) is less than or equal to two. In some examples, at least one of the one or more conditions is based on a value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion. In some examples, at least one of the one or more conditions is satisfied if the value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion is less than or equal to four. In some examples, at least one of the one or more conditions is based on a product of a value of a number of paging occasions per paging frame (Ns) and a value of a sum of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion. In some examples, at least one of the one or more conditions is satisfied if the value of the product is less than or equal to sixteen. In some examples, at least one of the one or more conditions is satisfied if the number of spare bits in the DCI is greater than or equal to sixteen. In some examples, the one or more conditions are satisfied if a second indication is received from the second apparatus indicating to determine the first at least one bit based on the shifted starting bit position. In some examples, the method further comprises applying an offset value to the first starting bit position for determining the shifted starting bit position if one or more of conditions are satisfied. In some examples, the method further comprises receiving the offset value from the second apparatus. In some examples, the method further comprises calculating the offset value based, at least in part, on a number of used bits in the DCI and / or a number of spare bits in the DCI. In some examples, the first apparatus calculates the offset value based on information comprised in a system information block (SIB), comprising one or more of a physical control channel configuration (PCCH-Config) information element, a number of subgroups per paging occasion, a number of subgroups per user equipment (UE) identity, and / or tracking reference signal availability indication. In some examples, the method further comprsies calculating the number of used bits based on: k = ns * (subgroupsNumPerPO-r!7 + subgroupsNumForUEID-rl7~) + (indBitID+Y) where k=number of used bits ns= PCCH-Config information element; subgroupsNumPerPO-rl7 = number of subgroups per paging occasion; subgroupsNumForUEID-rl7 = number of subgroups per user equipment UE identity; and indBitID= tracking reference signal (TRS) availability indication. In some examples, the offset value is equal to k+1. In some examples, the method further comprises determining the shifted starting bit position to be based on a least significant bit of the DCI. In some examples, the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasion index of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI. In some examples, the shifted starting bit position is determined based on: maxDCI-2-7-Size-rl7 — (iP0 ■ K + iSG), where maxDCI-2-7-Size-rl7= total number of bits of the DCI; iP0 = paging occasion index of the UE; K = N$° the number of subgroups per PO; and iSG = subgroup index of the UE. In some examples, the first apparatus is a user equipment and the second apparatus is a base station (gNB) and / or a network node. In some examples, said determining whether to monitor a paging occasion is based on the first indication. According to a third aspect, there is provided a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method of any preceding method definition in the second aspect. According to a fourth aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing a method, comprising: receiving, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI; receiving, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus; determining whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions; determining the first at least one bit of the PEI message based on the shifted starting bit position; and determining whether to monitor a paging occasion based, at least in part, on the first indication. The program instructions of the fourth aspect may also perform operations according to any preceding method definition of the second aspect. According to a fifth aspect, this specification describes a first apparatus in a mobile communications system comprising: means for receiving, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI; means for receiving, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus; means for determining whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions; means for determining the first at least one bit of the DCI based on the shifted starting bit position, if at least one of the one or more conditions are satisfied; and means for determining whether to monitor a paging occasion based, at least in part, on the first indication. The computer program instructions of the fifth aspect may also perform operations according to any preceding method definition of the second aspect. Brief Description of the Drawings Example embodiments will now be described by way of non-limiting example, with reference to the accompanying drawings, in which: FIGs. 1 to 2 are a block diagrams a system in accordance with example embodiments; FIGs. 3 and 4 are flowcharts of algorithms in accordance with example embodiments; FIG. 5 is a message flow sequence in accordance with an example embodiment; Fig. 6 is an example message in accordance with an example embodiment; FIGs. 7 to 9 are flow charts of an algorithm in accordance with example embodiments; FIG. 10 is a schematic diagram of a system that may be used to implement one or more of the example embodiments; and FIG. 11 shows tangible media for storing computer-readable code which when run by a computer may perform methods according to example embodiments described herein. Detailed Description FIG. 1 is a block diagram of an example system, indicated generally by the reference numeral 10, in accordance with an example embodiment. System 10 shows a first apparatus, such as a user equipment (UE1), 11, and a second apparatus, such as a base station or network node (gNB), 12. The system 10 may comprise a plurality of UEs, such as a further UE (UE2), 13. As discussed earlier, in 5G, paging is the mechanism by which the network alerts User Equipment (UE) about incoming data, messages, or calls when the device is, for example, in RRC idle or inactive mode. This process enables UEs to stay in low-power states, waking only when there is relevant information from the network, thereby saving battery life. A Paging Early Indication (PEI) is an early signal that notifies UEs about whether to monitor for a message in an upcoming PO, allowing UE to monitor next PO only if there is a relevant message, reducing the time they spend actively monitoring for a message. A gNB, such as the second apparatus 12, may send a PEI to a subgroup of UEs (e.g. a subgroup comprising UE1 and UE2), where both the UEs in a specific subgroup may monitor for paging if the subgroup to which the UE belongs is paged as indicated via the associated bit in the PEI. However, it is possible that a certain paging indication in PEI is only applicable to a first one (e.g. first apparatus 11) of the plurality of UEs in a subgroup. However, if the paging indication in the PEI is sent to all of the UEs in the subgroup (e.g. all the UEs that are assigned to the same subgroup and which read the paging indication in the same bit of the PEI), then the UE(s) other than the first apparatus 11 may exit the low-power state in order to monitor for a paging occasion, even though the paging indication may not be applicable for them. Therefore, this may cause a false paging alarm for the UEs other than the first apparatus 11. There remains a need for reducing the false paging alarm rate. The Paging Early Indication (PEI) message comprises an early signal which notifies UEs about whether they should monitoring for paging in the upcoming PO, allowing UE to monitor next PO, reducing the time they spend actively monitoring for a message. This early indication further enhances power efficiency by use of subgrouping per PO. For example, UEs belonging to one PO may be divided into 4 subgroups to further reduce the false paging alarm rate (i.e. UE detects the paging downlink control information (DCI), but does not find its UE ID in the paging record). As discussed in the 3GPP, Release 19, paging adaptation enhancements aim to reduce the number of distributed paging transmissions by grouping the paging occasions of different UEs closely together in time. This clustering allows for longer cell sleeping periods in between the paging transmissions and may enable the network to assign fewer distributed random-access occasions for UE responses (discussed below with reference to FIG. 2). Additionally, it allows the network to concentrate reference signal transmissions near these clustered paging occasions, ensuring the UE is prepared to receive the paging. The implementation involves extending the paging frequency (PF) interval, creating more spacing between paging frames compared to the traditional interval. Each extended paging frame can accommodate more POs, maintaining the overall paging capacity. The maximum PF interval may be up to 32 radio frames (previously being on 16 radio frames). Such doubling of the PF interval may require that the number of POs per PF is also doubled (e.g. from up to 4 POs per PF to up to 8 POs per PF). Importantly, clustering paging occasions may not affect paging latency, as clustering only modifies the distribution of POs within the existing paging cycle for UEs (Release 19 UEs), leaving the cycle duration unchanged. This approach enables legacy UEs (e.g. earlier releases) to continue operating under the original paging scheme, ensuring backwards compatibility and preventing the need for "Release 19 UE-only" cells. Release 19 WID Objectives in RP-234065: Time-Domain Paging Adaptation for Enhanced Network Energy Efficiency Example embodiments are targeted to at least the Release 19 WID in RP-234065. The work item contains the following objective on paging adaptation in time domain for network energy saving: 1. Specify adaptation of common signal / channel transmissions. [RAN1 / 2 / 3 / 4] • Adaptation of SSB in time domain, e.g. adapting periodicity • Adaptation of PRACH in time domain • Study adaptation of PRACH in spatial domain, e.g. non-uniform PRACH resources per SSB, and specify if found beneficial This study is to be done in 2Q'2O24 only • Adaptation of paging occasions including confining the paging occasions in the time domain Note: there shall be no paging latency increase Note: there shall be no negative impact to legacy UEs, unless significant benefits are shown RAN2 Release 19 Agreements The following are the agreements for Release 19 Paging Adaptation: hi RAN2#125bU meeting, adaptation of paging uecasum for network energy saving was ftuthei discussed with the below agreements. ; 1. From the UE point of view, UE will monitor one;PEEPO every paging DRX cycle, i.e. the UE ; ; doesn't skip FO in paging DRX cycle. i • 2. For adaptation of paging ercahons in t ime domain- RAN2 io :4udy a> bundle paging frames and b> • • extend the values of N to have increased interval between PFs (e.g. 7 / 64, 1 126 .„)and • : compensating decrease in number of EEs by increasing POs per PF. : ; 3. For Paging adaptation. .R2 discusses the following options on compatibility of legacy i RRC - Upturn E Prevent the access of legacy UE via barring; : - Updoa 2; Separate paging resources for legacy UEs and Rei-19 NFS UEs (assuming there are : legacy UEs) 1 RAN2 #127bis: Baseline Selection: Select option-b as baseline for R19 NES paging enhancement. Signaling Overhead Minimization: RAN2 should aim at signaling overhead minimization (e.g., Ns=8 and FFS for other larger values) extend the values of N and ns (from 4 to 8 per frame). Legacy and Release 19 UE Coexistence: Allowing legacy and R19 UEs to co-ex in the same PF / PO is possible, based on NW configuration. Legacy UE Compatibility: Legacy UE is not barred. Release 19 UE Monitoring: Rel-19 UEs only monitor the PO(s) according to Rel-19 paging configuration. 5 At RAN2 #128 (November 2024) the following discussion and agreements were made (Per RAN2 #128 meeting report): Agreements on paging adaptation 1. Introduce value for Ns=8. FFS on 16. 2. Introduce value for N= T / 32. FFS on T / 64, T / 128, T / 256. Kev Paging Parameters In TS 38.331, key parameters such as Paging Frame (PF) periodicity, Paging Occasion 10 (PO) per PF, and Paging Early Indication (PEI) configuration are defined as follows to xtebye foe nufftust c? to&: [X-sgx^ tointos •;; Y (corrc'ipoftoir.g: to :V m TS 38-,504 £2¾} 3?>G £>«•$«$ Sra!*^ to ps^to-otor S-F.^tosi i« YS 38.304 {20-:. A ;<s:ue of crf^Sr^'feemf;T biN»«sp<s^3s to ? ■ to, 3 yakra of tweE^ntoY c<x<e$:p-p3bto ?$ f 7 8, 3«! so or. f?to set fc-2eto sodif SSfi’SOH i>tork atto CORE.SET ri^'i^xir-g to 2 or 3:as soe-oihed to io 38.253ff 3^>: • to; to &« <0 w-s. M co;: ba oa' la 2:10 a' -ortoY, Ad4T, Qi,-*?f8f?, orro^jfeerto?} kx swb-fwX-jScrty^ of 2k ros 01:1 b« s<4 to >xi>o to (kv.Y?’ Oc-’irt^rT. oj^£x?’8fk?. ?} - fur ,sxb--£>£;toO‘to:f>'S^ of 40 013 W car; f>t: so* to ixw <4 ^urto / Y. coei'ATesf^T) ’ to; c? SO ins. N cao lt<- swi to«>« o: Jw:e£8jW:H. c.oe&-xtee<48?; •- Jot c-J 'toC- toi. -x oe to <to&S''xie8rto?' to sei k; 2«to 308 if SS??>S£H iotork atto CCRt SE’f fouKi^x-rg ^aifeto to 1 {&-a>£8£;fefi to Y& i& 2 v3 {'?3j,r. N Soft be seitocne of ^*7. ?' k88gS2$38^?fS0o£cr32to^^_to^toJ2iG^2h800tofto8f^_toj50^2£i^EL2^ ________________________________________ Currently, the PEI can handle up to 4 POs per PF (and a total of 8 POs for 2 PF since po-NumPerPEI-rl7 is maximum 8). With the R19 R.AN2 agreement to increase the 5 number of POs from 4 to 8 per PF, existing PEI configurations will need updates to support more than 4 POs per PF. Paging and its parameter in 3GPP Specifications In 38 304 V15.3.0 Paging is explained as follows: 7 Paging 7.1 Discontinuous Reception for paging The UE may use Discontinuous Reception (DRX) in RRC_IDLE and RRC_INACTIVE state in order to reduce power consumption. The UE monitors one paging occasion (PO) per DRX cycle. A PO is a set of PDCCH monitoring occasions and can consist of multiple time slots (e.g. subframe or OFDM symbol) where paging DCI can be sent (TS 38.213 [4]). One Paging Frame (PF) is one Radio Frame and may contain one or multiple PO(s) or starting point of a PO. In multi-beam operations, the UE assumes that the same paging message is repeated in all transmitted beams and thus the selection of the beam(s) for the reception of the paging message is up to UE implementation. The paging message is same for both RAN initiated paging and CN initiated paging. The UE initiates RRC Connection Resume procedure upon receiving RAN initiated paging. If the UE receives a CN initiated paging in RRC_INACTIVE state, the UE moves to RRC_IDLE and informs NAS. The PF and PO for paging are determined by the following formulae: SFN for the PF is determined by: (SFN + PF_offset) mod T = (T div N)*(UE_ID mod N) Index (i_s), indicating the index of the PO is determined by: i_s = floor (UE_ID / N) mod Ns The PDCCH monitoring occasions for paging are determined according to pagingSearchSpace as specified in TS 38.213 [4] and firstPDCCH-MonitoringOccasionOfPO 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]. When SearchSpaceld other than 0 is configured for pagingSearchSpace, the UE monitors the (i_s + l)th PO. A PO is a set of 'S' consecutive PDCCH monitoring occasions where 'S' is the number of actual transmitted SSBs determined according to ssb-PositionsInBurst in SIB1. The Kth PDCCH monitoring occasion for paging in the PO corresponds to the Kth transmitted SSB. The PDCCH monitoring occasions for paging which do not overlap with UL symbols (determined according to tdd-UL-DL-ConfigurationCommon) 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 + l)th PO is the (i_s + l)th value of the firstPDCCHMonitoringOccasionOfPO parameter; otherwise, it is equal to i_s * S. The following parameters are used for the calculation of PF and i_s above: T: DRX cycle of the UE (T is determined by the shortest of the UE specific DRX value, if configured by RRC or upper layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by RRC or by upper layers, the default value is applied). N: number of total paging frames in T Ns: number of paging occasions for a PF PF_offset: offset used for PF determination Parameters Ns, nAndPagingFrameOffset, and the length of default DRX Cycle are signaled in SIB1. The values of N and PF_offset are derived from the parameter nAndPagingFrameOffset as defined in TS 38.331 [3]. The parameter first-PDCCH-MonitoringOccasionOfPO is signalled in SIB1 for paging in initial DL BWP. For paging in a DL BWP other than the initial DL BWP, the parameter first-PDCCH-MonitoringOccasionOfPO is signaled in the corresponding BWP configuration. UE Power Saving and Suboroupinq Mechanisms in 3GPP TS 38.331 In 3GPP TS 38.300, UE power saving for paging monitoring is explained in Section 9.2.5, covering CN-controlled subgrouping and UE ID-based subgrouping. 9.2.5 Paging UE power saving for paging monitoring: in order to reduce UE power consumption due to false paging alarms, the group of UEs monitoring the same PO can be further divided into multiple subgroups. With subgrouping, a UE shall monitor PDCCH in its PO for paging if the subgroup to which the UE belongs is paged as indicated via associated PEI. If a UE cannot find its subgroup ID with the PEI configurations in a cell or if the UE is unable to monitor the associated PEI occasion corresponding to its PO, it shall monitor the paging in its PO. These subgroups have the following characteristics: - They are formed based on either CN controlled subgrouping or UE ID based subgrouping. - If CN controlled subgroup ID is not provided from AMF, UE ID based subgrouping is used if supported by the UE and network. - The RRC state (RRC_IDLE or RRC_INACTIVE state) does not impact which subgroup the UE belongs to; - Subgrouping support for a cell is broadcast in the system information as one of the following: Only CN controlled subgrouping supported, only UE ID based subgrouping supported, or both CN controlled subgrouping and UE ID based subgrouping supported. - Total number of subgroups allowed in a cell is up to 8 and represents the sum of CN controlled and UE ID based subgrouping configured by the network. - A UE configured with CN controlled subgroup ID applies CN controlled subgroup ID if the cell supports CN controlled subgrouping: otherwise, it derives UE ID based subgroup ID if the cell supports only UE ID based subgrouping PEI associated with subgroups has the following characteristics: - If the PEI is supported by the UE, it shall at least support UE ID based subgrouping method; - PEI monitoring can be limited via system information to the last used cell (i.e., the cell in which the UE most recently received RRCRelease without indicating that the last used cell for PEI shall not be updated); - A PEI-capable UE shall store its last used cell information; gNBs supporting the PEI monitoring to the last used cell function provide the UE's last used cell information to the AMF in the NG-AP UE Context Release Complete message for PEI capable UEs, as described in TS 38.413

[26] ; - UE that expects MBS group notification shall ignore the PEI and shall monitor paging in its PO. CN controlled subgrouping: For CN controlled subgrouping, AMF is responsible for assigning subgroup ID to the UE. The total number of subgroups for CN controlled subgrouping which can be configured, e.g. by OAM is up to 8. It is assumed that CN controlled subgrouping support is homogeneous within an RNA. UE ID based subgrouping: For UE ID based subgrouping, the gNB and UE can determine the subgroup ID based on the UE ID and the total number of subgroups for UE ID based subgrouping in the cell. The total number of subgroups for UE ID based subgrouping is decided by the gNB for each cell and can be different in different cells. Monitoring for Early Paging Indication The PEI DCI format 2_7 is defined in 38.212 and 38.213. TS 38.213 A paging indication field of DCI format 2JJ includes wdo' segments of K bits, where K = For a subgroup index iSG, 0 <iSG <K, a UE determines a value for the (Spo • + bit in the paging indication field, where iP0 = ((UEJDmodN) • Ns + i_s)modNpQl is a paging occasion index, and N, Ns, iSG, and i_s are defined in [17, TS 38.304], and UEJD is defined in clause 7.1 of [17, TS 38.304]. When the value is '1', the UE monitors a paging occasion determined according to [17, TS 38.304]; otherwise, the UE is not required to monitor the paging occasion. The size of DCI format 2_7 is indicated by the higher layer parameter payloadSizeDCI-2-7, according to Clause 10.4A of [5, TS 38.213]. The number of information bits in format 2_7 shall be equal to or less than the payload size of format 2_7. If the number of information bits in format 2JJ is less than the size of format 2_7, the remaining bits are reserved. TS 38.212 section 7.3.1.3.8 Format 2_7 DCI format 27 is used for notifying the paging early indication and TRS availability indication for one or more UEs. The following information is transmitted by means of the DCI format 2_7 with CRC scrambled by PEI-RNTI: Paging indication field - Npo’N™ bit(s), where Npo1 is the number of paging occasions configured by higher layer parameter po-NumPerPEI as defined in Clause 10.4A in [5, TS 38.213]; Ng°\s the number of sub-groups of a paging occasion configured by higher layer parameter subgroupsNumPerPO. Each bit in the field indicates one UE subgroup of a paging occasion. TRS availability indication - 1, 2, 3, 4, 5, or 6 bits, where the number of bits is equal to one plus the highest value of all the indBitlD(s) provided by the trs-ResourceSetConfig or the number of bits is equal to one plus the highest value of all the indBitID-rl8(s) provided by the trs-ResourceSetConfig-rl8 if configured if configured; 0 bits otherwise. FIG. 2 is a block diagram of a system, indicated generally by the reference numeral 20, in accordance with an example embodiment. 5 A timeline 21 shows a legacy approach, where the paging frame interval (e.g. between PF1 and PF2) is equal to 16 radio frames (ms). Currently, the PEI can be configured to address up to 8 POs in 2 PFs or 4 POs in 1 PF. Furthermore, the number of PEI subgroups is maximum 8 per PO. Furthermore, the maximum DCI size is 43 bits according to TS 38.331. Increasing the size to address 8 POs in 1 PF is not desirable 10 because it will then not be decodable by the legacy UEs. A network energy saving (NES) scenario assumes low paging load. This implies the PFs may be sparse and thus addressing two consecutive PFs with one PEI will result in a large PEI-PF time distance, which is bad for UE energy consumption. The reason is 15 that a UE monitoring a PO associated with the second PF of the PEI will have to monitor the PEI, which is transmitted before the first PF and then wait a complete PF interval before it has to monitor its own PO. A timeline 22 shows an extended paging frame interval, where the PF interval may be increased to at least 32 radio frames, while the number of POs per PF may be increased to at least 8. Therefore N_PO per PEI may be 4 instead of 8 in low load scenarios. This leaves spare bits in the PEI DCI if K (#subgroups) is not increased from 4 to 8. Increasing K from 4 to 8 may not be feasible, because it would require a UE-specific RRC / NAS reconfiguration to assign a new subgroup to a UE as compared to changing the PF interval when the paging load changes as the PF interval is indicated in SIB1. Assuming there are 4 POs allocated to a legacy PF (Ns = 4) and 4 subgroups per PO (K = 4), then the information bits used in PEI DCI is 4*4=16. Furthermore, the TS 38.212 defines up to 6 bits are allocated for the TRS availability indication, if TRS is configured for RRC idle / inactive mode UEs. In the considered example, this means 16+6 information bits are used in total, while there are 43-22=21 unused bits in the DCI, which from legacy UE point-of-view will be considered reserved (i.e. padded with random data) and will be ignored by legacy UEs. A UE (Release 19 UE) assigned to a PO larger than 4 may need to share the same bit in the PEI as legacy UEs (which can be assigned to the legacy up to first 4 POs per PF). This increases the false paging alarm rate, which is undesired. The example embodiments described herewith aim to reduce false paging alarms by making use of certain unused bits in the PEI DCI to convey the paging indication to Release 19 UEs, which otherwise are considered as spa re / reserved by legacy UE and transmitted as padded bits by the network. FIG. 3 is a flowchart of an algorithm, indicated generally by the reference numeral 30, in accordance with an example embodiment. The operations of algorithm 30 may be carried out at a first apparatus, such as a user equipment (UE), of a mobile communications system. The algorithm 30 starts at operation 31, where the first apparatus receives, from a second apparatus (e.g. a base station / gNB), a Paging Early Indication (PEI) configuration. The PEI configuration may comprise a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI. The number of paging occasions per PEI will herein be referred to as po-NumPerPEI. Next, at operation 32, the first apparatus receives, from the second apparatus, a downlink control information (DCI) comprising a PEI message. The PEI message may comprise a first indication of whether a paging occasion is to be monitored by the first apparatus. At operation 33, the first apparatus performs a first determination of whether a first at least one bit should be determined based on a first starting bit position or a shifted starting bit position. The first at least one bit may comprise the first indication that indicates whether a paging occasion is to be monitored by the first apparatus. The determination may be based, at least in part, on a number of used bits in the DCI. In one example, the first starting bit position may be a bit position that carries the PEI according to legacy rules. For example, the first starting bit position may be determined based on the equation: ((UEJDmodN) • Ns + i_s)modNpQl as per TS 38.213. In some example embodiments, the first apparatus may determine the first at least one bit based on the shifted starting position if the number of used information bits in the DCI is smaller than a first threshold and / or a number of spare bits in the DCI is larger than a second threshold. It should be noted that the bits should be seen as information bits or spare bit by legacy UEs. In some examples, the first threshold is based on payloadSizeDCI-2-7. In some examples, the number of spare bits is derived based on the number of used bits and payloadSizeDCI-2-7. In some examples, the first and / or second threshold is included in the PEI configuration. Alternatively, or in addition the first and / or second threshold is standardised, such as, by being specified in a Release specification. Next, operation 34 may be performed if the first determination is that the first at least one bit should be determined based on the shifted starting bit position. At operation 34, the first apparatus may determine the first at least one bit based on the shifted starting position. The operation 34 may optionally comprise determining the shifted starting bit position and / or receiving information from the second apparatus associated with the shifted starting position. In one example, the first apparatus may receive from the second apparatus, at an optional operation 36, a second indication of whether the shifted starting bit position should be determined based on an offset value or based on a least significant bit (LSB) of the DCI. Alternatively, or in addition, at an optional operation 37, the first apparatus may determine the shifted starting bit position based on certain parameters related to PEI such as po-NumPerPEI-rl7, subgroupConfig-rl7, and / or tracking reference signal (TRS) bits, or an offset value that is based on the number of used bits in the DCI, or based on a LSB of the DCI. At operation 35, the first apparatus determines whether to monitor a paging occasion based, at least in part, on the first indication. As indicated earlier, the first apparatus may be a user equipment (UE), and the second apparatus may be a base station (gNB) or a network node. In an example embodiment, the number of used bits is based on a determination of a product of the poNumPerPEI and a number of subgroups and optionally based on a number of tracking reference signal bits. In an example embodiment, the PEI message is comprised in a downlink control information (DCI) format 2_7. In an example embodiment, the number of used bits in the DCI is a total number of used bits based on one or more of: po-NumPerPEI-rl7, subgroupConfig-rl7, and / or tracking reference signal (TRS) bits. For example, the number of used bits in the DCI is a total number of used bits for legacy information based on a product of the poNumPerPEI and the number of subgroups of UE associated with a paging occasion and further based on the TRS Availability Indication bits. For example, the shifted starting bit position may be comprised in a spare bit of the DCI. For example, by using certain bits in the DCI format 2JJ (i.e. DCI for PEI indication) to address Rel-19 UEs, and which legacy UEs consider as 'spare' / 'reserved' bits. In one example, considering the scenario of the example of timeline 22 as described with reference to FIG. 2, if the PF interval is increased to at least 32 radio frames, while the number of POs per PF is increased to at least 8, the po-NumPerPEI may be 4 in low load scenarios. This leaves spare bits in the PEI DCI. Assuming there are 4 POs allocated to a legacy PF (Ns = 4) and 4 subgroups per PO (K = 4), then the bits used in PEI DCI is 4*4=16. Furthermore, the TS 38.212 defines up to 6 bits are allocated for the TRS availability indication. In the considered example, this means 16+6 bits are used in total, while there are 43-22=21 unused bits in the DCI, which from legacy UE PoV will be considered reserved (i.e. padded with random data) and will be ignored by legacy UEs. As such, in operation 33, the first determination may indicate that the first at least one bit should be determined based on the first starting position if the po-NumPerPEI is above 4 (e.g. above 8 according to legacy approach), such that the UE monitors the same bit as a legacy UE having the same iP0, i.e. based on iP0 = ((UEJDmodN) • Ns + i_s)modNpQ as per TS 38.213. Alternatively, in operation 33, the first determination may indicate that the first at least one bit should be determined based on the shifted starting bit position if the po-NumPerPEI (NPo') is 4 or less. As such, for example, those reserved bits in the DCI are used to target release 19 UEs (and beyond) if 8 or more POs are configured per PF. If the po-NumPerPEI is above 4 (i.e. 8 according to the current specification), the rel-19 UE monitors the same bit as a legacy UE having the same iP0, i.e. based on iP0 = ((UEJDmodN) • Ns + i_s)modN$l as per TS 38.213. In an example embodiment, the first apparatus determines the shifted starting bit position based on an offset value. For example, the offset value may be determined by the first apparatus, based, at least in part, on one or more of: the po-NumPerPEI; a number of subgroups of user equipment (UE) associated with a paging occasion; and / or a number of bits allocated for Tracking Reference Signal (TRS) availability. Alternatively, or in addition the first apparatus receives the offset value from the second apparatus. In one example, the offset value may be received from the second apparatus as part of the PEI configuration. In one example, the first apparatus determines the shifted starting bit position based on equation: (ipo ’ K + iSG + ioffset-rig), where iP0 = paging occasion index of the first apparatus (UE) (e.g. based on the equation in 38.213); K = N$° the number of subgroups per paging occasion; iSG = subgroup index of the first apparatus (UE); and ^offset—ri9 = offset value. In an alternative example embodiment, the first apparatus determines the shifted starting bit position to be based on a least significant bit (LSB) of the DCI (e.g. bit 43 (i.e. opposite starting position compared to legacy UEs starting at MSB I bit 0). In this case, the explicit offset does not need to be signaled). For example, the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasion index of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI. The UE may assume the first subgroup i_SG=0 of the first release 19 PO is at the LSB of the DCI (i.e. bit 43). The LSB+1 (i.e. bit 42) may then be for the second subgroup of the first PO and so forth. If the number of subgroups is 1, the LSB+1 will map to the second PO. The applied equation may be: Shifted starting bit position = maxDCI-2-7-Size-rl7 — (ipo • + Lsg), In an example embodiment, the first apparatus receives (e.g. operation 36) a second indication from the second apparatus of whether the shifted starting bit position should be determined based on an offset value or based on a least significant bit (LSB) of the DCI. In an example embodiment, the first apparatus monitors a paging occasion if the first at least one bit is set to '1'. FIG. 4 is a flowchart of an algorithm, indicated generally by the reference numeral 40, in accordance with an example embodiment. The operations of algorithm 40 may be carried out at a second apparatus, such as a base station (gNB), of a mobile communications system. The algorithm 40 starts at operation 41, where the second apparatus sends, to a first apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI. Next, at operation 42, the second apparatus sends, to the first apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus. Next, at operation 43, based on a number of used bits in the DCI, the second apparatus sends a second indication to the first apparatus for determining a first at least one bit based on a shifted starting position. The first at least one bit comprises the first indication. In one example, the second apparatus sends the second indication for configuring the first apparatus to determine the first at least one bit based on the shifted starting position if the number of used bits in the DCI is smaller than a first threshold and / or a number of spare bits in the DCI is larger than a second threshold. The second threshold may be determined based on the product of the poNumPerPEI and the number of subgroups. In one example, at an optional operation 44, the second apparatus may send a third indication to the first apparatus of whether the shifted starting bit position should be determined based on an offset value or based on a least significant bit of the DCI. In one example, at another optional operation 45, the second apparatus may send the offset value to the second apparatus. For example, the offset value is sent as part of the PEI configuration. In one example, the second apparatus may determine the offset value based, at least in part, on one or more of: the po-NumPerPEI; a number of subgroups of user equipment (UE) associated with a paging occasion; a number bits allocated for Tracking Reference Signal availability. In one example, the second apparatus sets the first at least one bit to '1' if first indication is to indicate that the paging occasion is to be monitored by the first apparatus. FIG. 5 is a message flow, indicated generally by the reference numeral 50, in accordance with an example embodiment. The message flow 50 shows communication between UE 51 (e.g. first apparatus) and gNB 52 (e.g. second apparatus). The gNB 52 sends a message 53 to the UE 51 comprising a PEI configuration, where the PEI configuration includes po-NumPerPEI. In some examples, the PEI configuration may further comprise an offset value (as described above), and / or an indication of whether or not an offset value should be applied in order to determine the first at least one bit comprising a first indication of whether a paging occasion is to be monitored. In a first scenario (e.g. Rel-19 UE) where the number of used bits of a DCI comprising a PEI message is less than a first threshold, and / or the number of spare bits in the DCI is greater than a second threshold, the operations 54 and 56 may be performed, and the PEI 55 may be sent by the gNB 52 to the UE 51. For example, the first scenario is applicable if po-NumPerPEI is less than or equal to 4. At operation 54, the UE 51 may determine that the po-NumPerPEI is less than or equal to 4, and then may consider a shifted starting bit position (e.g. apply an offset value and / or consider LSB of DCI) for determining the first at least one bit to be monitored for the PEI. The gNB 52 may send a PEI 55 to the UE 51, where the PEI 55 may comprise information in the spare bits (e.g. used for Rell9 UEs). In other words, a paging indication is included in one of the spare bits (rather than a used bit according to legacy rules) of the DCI comprising the PEI. The relevant spare bit of the DCI that comprises the paging indication is equivalent to the shifted starting position as determined by the UE 51 at operation 54. At operation 56, the UE 51 may determine whether to monitor for paging occasion based on the value of the spare bit (in the shifted starting bit position). For example, if the value is '1', then the UE 51 monitors for a paging occasion. In a second scenario (e.g. legacy UE) where the number of used bits of a DCI comprising a PEI message is greater than a first threshold, and / or the number of spare bits in the DCI is less than a second threshold, the operations 57 and 59 may be performed, and the PEI 58 may be sent by the gNB 52 to the UE 51. For example, the second scenario is applicable if po-NumPerPEI is more than 4. At operation 57, the UE 51 may determine that the po-NumPerPEI is greater than 4, and then may consider first starting bit position (e.g. according to legacy rules) (e.g. not applying an offset value and not considering LSB of DCI) for determining the first at least one bit to be monitored for the PEI. The gNB 52 may send a PEI 58 (with a format according to legacy rules) to the UE 51, and the UE 51 may determine, at operation 59, whether to monitor for paging occasion based on the value of the first starting bit position (in the legacy part of the PEI). In some example embodiments, if the po-NumPerPEI (Npo1) is 4 or less (i.e. the PEI only addresses one legacy PF), the (release 19) UE determines the starting bit position to monitor in the DCI format 2_7 as follows: the starting bit position is defined by adding an offset lOffset-rw to the legacy equation: (iP0 ■ K + iSG + ioff set-rl^ i Where iP0 = paging occasion index of the UE (based on the equation in 38.213) K = N$° the number of subgroups per PO iSG = subgroup index of the UE For example, the offset value may allow taking into account the number of bits occupied by legacy signaling (#POs, #subgroups, #TRS availability indication bits) in the DCI ensuring that R19 UEs use only reserved bits in the DCI. In one example, the offset value may be explicitly signaled by the base station, for example, as part of the PEI configuration. Alternatively, or in addition, the offset value may be implicitly calculated by the UE based on the number of bits occupied by legacy signaling (#POs, #subgroups, #TRS bits). In yet another example, the offset value may be hardcoded in the 3GPP specification, e.g. considering a fixed number of POs in the PEI, subgroups and TRS bits. In one example, the base station (network node) can signal whether the UE shall apply the offset value or not. For example, if the UE is configured not to apply an offset value, the (release 19) UE may be configured to determine the shifted starting position based on a mapping of bits from a least significant bit (LSB- bit 43) (i.e. opposite starting position compared to legacy UEs starting at most significant bit (MSB)- bit 0). In this case, the explicit offset does not need to be signaled. In another example, the UE may autonomously apply the offset based on conditions being satisfied (e.g. #POs allocated to legacy and rel.l9+ UEs, number of subgroups, number of spare bits in the DCI). The UE may determine the specific bit in the PEI to monitor based on its own PO. In one embodiment, the first 4 POs / PF of the rel.19 UEs are mapped to the legacy bits in the DCI - by using the legacy equation, while the remaining POs (at least 4) are mapped to the spare bits of the DCI (by applying the ioffset-ng parameter). Alternatively, or in addition, all POs of the rel.19 UEs are mapped to the spare bits. The following options may be considered: Option 1-mapping some POs / PF of the Release 19 UEs on the legacy bits, and mapping the remaining POs of the Release 19 UEs to the spare bits; Option 2- mapping all POs of release 19 UEs to spare bits), then the mapping may be hardcoded according to the standards specification. If more than one option is adopted, then the network (base station) may indicate (e.g. in the PEI configuration) which option should be applied by the UE. It should be appreciated that the both the UE and gNB should be aware (e.g. synchronized) about which bits should be monitored by the UE in the PEI. Any discrepancies in the UE's configuration and the gNB's information of the relevant bit to be monitored may cause paging failures or false paging alarms. In one example, different (release 19) UEs may be configured with different numbers of subgroups per PO to perform the mapping. FIG. 6 is an example message, indicated generally by the reference numeral 60, in accordance with an example embodiment. The message 60 is an illustration of a PEI message in a DCI 2JJ format. For example, bits 1-4 are associated with 4 subgroups associated with a first PO (PO #0), bits 5-8 are associated with 4 subgroups associated with a second PO (PO #1), bits 9-12 are associated with 4 subgroups associated with a third PO (PO #2), bits 13-16 are associated with 4 subgroups associated with a fourth PO (PO #3). Further, one or more of bits 17-22 may optionally by associated with a tracking reference signal (TRS). That may allow the DCI to have at least 19 spare bits (out of total 43 bits). Therefore, bits 23-43 may be considered to be spare bits that are monitored by (release 19) UEs in the PEI. FIG. 7 is a flowchart of an algorithm, indicated generally by the reference numeral 70, in accordance with an example embodiment. The operations of algorithm 70 may be carried out at a first apparatus, such as a user equipment (UE), of a mobile communications system. The algorithm may start at operation 71 (e.g. similar to operation 31), where the first apparatus may receive, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI. Next, at operation 72 (e.g. similar to operation 32), the first apparatus may receive, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus. At operation 73, the first apparatus may receive, from the second apparatus, a second indication. The second indication may comprise one or more of: information of whether a first at least one bit should be determined based on a first starting bit position (e.g. a bit position that carries the PEI according to legacy rules) or a shifted starting bit position (e.g. a bit position from the spare bits of the DCI); or information of a shifted starting bit position for the first at least one bit. As described earlier, the first at least one bit comprises the first indication of whether a paging occasion is to be monitored by the first apparatus. In one example, the second indication is based, at least in part, on a determination of a product of the poNumPerPEI and a number of subgroups. In one example, the second indication indicates that the first at least one bit should be determined based on the shifted starting bit position if a number of used bits in the DCI is smaller than a first threshold and / or a number of spare bits in the DCI is larger than a second threshold. At operation 74, the first apparatus may determine the first at least one bit based on the second indication. At operation 75, the first apparatus may determine whether to monitor a paging occasion based, at least in part, on the first indication. In an example embodiment, the first apparatus may determine the shifted starting bit position based on an offset value to be applied to a first starting bit position. In one example, the offset value may be received from the second apparatus (e.g. as part of the PEI configuration. The offset value may be determined by the second apparatus based, at least in part, on one or more of: the po-NumPerPEI; a number of subgroups of user equipment (UE) associated with a paging occasion; a number bits allocated for Tracking Reference Signal (TRS) availability. In an example embodiment, the second indication further indicates that the shifted starting bit position is to be determined (e.g. by the first apparatus) based on equation: (ipo * + lSg T ^offset—ri^r where. iP0 = paging occasion index of the UE (based on the equation in 38.213) K = N$° the number of subgroups per PO iSG = subgroup index of the UE In another example embodiment, the second indication further indicates that the shifted starting bit position is to be determined based on a least significant bit of the DCI. For example, the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasion index of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI. In an example embodiment, the first apparatus may receive a third indication from the second apparatus of whether the shifted starting bit position should be determined based on an offset value or based on a least significant bit of the DCI. In one example, the first apparatus may monitor a paging occasion if the first at least one bit is set to '1'. FIG. 8 is a flowchart of an algorithm, indicated generally by the reference numeral 80, in accordance with an example embodiment. The operations of algorithm 80 may be carried out at a second apparatus, such as a base station (gNB), of a mobile communications system. The algorithm 80 starts at operation 81, where the first apparatus sends, to a first apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI. Next, at operation 82, the second apparatus sends, to the first apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus. At operation 83, the second apparatus sends a second indication to the first apparatus. The second indication may comprise one or more of: information of whether a first at least one bit should be determined based on a first starting bit position (e.g. a bit position that carries the PEI according to legacy rules) or a shifted starting bit position (e.g. a bit position from spare bits of the DCI); or information of a shifted starting bit position for the first at least one bit. For example, the first at least one bit comprises the first indication. For example, the second apparatus may indicate to the first apparatus (UE) whether a shift should be applied for monitoring for a PO, or whether a first bit position according to legacy rules should be monitored for the PO. Alternatively, or in addition, the second apparatus may simply inform the first apparatus of the relevant bit, i.e. the shifted starting bit position (e.g. assuming the legacy rules should not apply). In an example embodiment, at an optional operation 84, the second apparatus may send a third indication to the first apparatus of whether the shifted starting bit position should be determined based on an offset value or based on a least significant bit of the DCI. As described above, there may be at least two ways of determining the shifted starting bit position, including the calculation or determination of an offset value, or mapping based on the LSB of the DCI. In an example embodiment, at an optional operation 85, the second apparatus may send the offset value, for example as part of the PEI configuration, to the first apparatus (e.g. in the scenario that the shifted starting bit position is to be determined based on the offset value). In an example embodiment, the second apparatus may determine the offset value based, at least in part, on one or more of: the po-NumPerPEI; a number of subgroups of user equipment (UE) associated with a paging occasion; a number bits allocated for tracking Reference Signal (TRS) availability. In one example embodiment, the second apparatus may indicate, in the second indication, that the first at least one bit of the PEI message is to be determined based on the shifted starting bit position if the number of used bits in the DCI is smaller than a first threshold and / or a number of spare bits in the DCI is greater than a second threshold. For example, the second threshold may be determined based on the product of the poNumPerPEI and the number of subgroups. In an example embodiment, the second apparatus may set the first at least one bit to '1' if first indication is to indicate that the paging occasion is to be monitored by the first apparatus, and / or may set the first at least one bit to '0' if the first indication is to indicate that the paging occasion need not be monitored by the first apparatus. FIG. 9 is a flowchart of an algorithm, indicated generally by the reference numeral 90, in accordance with an example embodiment. The operations of algorithm 90 may be carried out at a first apparatus, such as a user equipment (UE), of a mobile communications system. The algorithm 90 starts at operation 91 (e.g. similar to operation 31), where the first apparatus receives, from a second apparatus (e.g. a base station / gNB), a Paging Early Indication (PEI) configuration. The PEI configuration may comprise a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI. Next, at operation 92 (e.g. similar to operation 32), the first apparatus receives, from the second apparatus, a downlink control information (DCI) comprising a PEI message. The PEI message may comprise a first indication of whether a paging occasion is to be monitored by the first apparatus. At operation 93, the first apparatus determines whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions. In one example, the first starting bit position may be a bit position that carries the PEI according to legacy rules. In one example, the determination of whether the conditions are satisfied may be performed at the UE without input from the gNB (e.g. UE autonomously decides whether or not to consider a shifted starting bit position). If at least one of the one or more conditions are satisfied, operation 94 may be performed, where the first apparatus may determine the first at least one bit of the DCI based on the shifted starting bit position. At operation 95, the first apparatus determines whether to monitor a paging occasion based, at least in part, on the first indication. In an example embodiment, at least one of the one or more conditions may be based on one or more of the po-NumPerPEI, a number of subgroups of user equipment (UE) associated with a paging occasion, a number of used bits in the DCI and / or a number of spare bits in the DCI. For example, at least one of the one or more conditions may be satisfied if the po-NumPerPEI is less than or equal to a first threshold. In one example, the first threshold is equal to four. As such, a condition may be satisfied if PEI-Config-rl7 information element po-NumPerPEI <= 4. In another example embodiment, at least one of the one or more conditions is based on a product of the po-NumPerPEI and the number of subgroups of UE associated with a paging occasion. For example, said product may be an indication of the number of used bits (e.g. number of used bits may be based on a determination of a product of the poNumPerPEI and a number of subgroups and optionally based on a number of tracking reference signal bits). For example, if said product is less than a threshold, at least one of the one or more conditions may be satisfied. In an example embodiment, at least one of the one or more conditions is based on a value of a number of paging occasions per paging frame (Ns). For example, Ns may be comprised in a physical (downlink) control channel configuration information element (PCCH-Config information element). In one example, at least one of the one or more conditions is satisfied if the value of the number of paging occasions per paging frame (Ns) is less than or equal to two (PCCH-Config information element ns <=2). In an example embodiment, at least one of the one or more conditions is based on a value of a sum of a number of core network (CN) controlled subgroups per paging occasion (subgroupsNumPerPO-rl7) and a number of user equipment identity (UE ID) controlled subgroups per paging occasion (subgroupsNumForUEID-rl7). For example, at least one of the one or more conditions is satisfied if the value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion is less than or equal to four. As such, a condition may be satisfied if a sum of subgroupsNumPerPO-rl7 and subgroupsNumForUEID-rl7 <= 4. In an example embodiment, at least one of the one or more conditions is based on a product of a value of a number of paging occasions per paging frame (Ns) and a value of a sum of a number of core network (CN) controlled subgroups per paging occasion (subgroupsNumPerPO-rl7) and a number of user equipment identity (UE ID) controlled subgroups per paging occasion (subgroupsNumForUEID-rl7). For example at least one of the one or more conditions is satisfied if the value of the product is less than or equal to sixteen. As such, a condition may be satisfied if the product of ns*(subgroupsNumPerPO-rl7 + subgroupsNumForUEID-rl7) <= 16. In an example embodiment, at least one of the one or more conditions is satisfied if the number of spare bits in the DCI is greater than or equal to sixteen. In some examples, the number of spare bits is derived based on the number of used bits and payloadSizeDCI-2-7. In some examples, the one or more conditions are satisfied if a second indication is received from the second apparatus indicating to determine the first at least one bit based on the shifted starting bit position. As such, instead of the first apparatus determining whether any of the abovementioned conditions are satisfied (e.g. PEI-Config-rl7 information element po-NumPerPEI <= 4; PCCH-Config information element ns <=2; Sum of subgroupsNumPerPO-rl7 and subgroupsNumForUEID-rl7 <= 4; The product of ns* (subgroupsNumPerPO-rl7 + subgroupsNumForUEID-rl7) <= 16; Number of spare bits => 16), the first apparatus considers at least one condition to be satisfied if the second indication is received from the second apparatus. In an example embodiment, the first apparatus may apply an offset value to the first starting bit position for determining the shifted starting bit position if one or more of conditions are satisfied. The first apparatus may receive the offset value from the second apparatus. Alternatively, or in addition, the first apparatus may (implicitly) calculate the offset value based, at least in part, on a number of used bits in the DCI and / or a number of spare bits in the DCI. For example, the first apparatus may calculates the offset value based on information comprised in a system information block (SIB), comprising one or more of a physical control channel configuration (PCCH-Config) information element, a number of subgroups per paging occasion, a number of subgroups per user equipment (UE) identity, and / or tracking reference signal availability indication. In an example embodiment, the first apparatus may calculate the number of used bits based on: k = ns * (subgroupsNumPerPO-rl7 + subgroupsNumForUEID-rl7 ) + (indBitID+1) where k=number of used bits; ns= PCCH-Config information element ns (number of Pos per PF); subgroupsNumPerPO-rl7 = number of CN controlled subgroups per paging occasion; subgroupsNumForUEID-rl7 = number of UE_ID controlled subgroups per user equipment UE identity; and indBitID= tracking reference signal (TRS) availability indication (SIB17 information element indBitID-rl7 (or indBitID-rl8 of SIB17bis)). In one example, the offset value is equal to k+1. In an example embodiment, the first apparatus may determine the shifted starting bit position to be based on a least significant bit of the DCI. The UE may assume the first subgroup i_SG=0 of the first release 19 PO is at the LSB of the DCI (i.e. bit 43). The LSB+1 (i.e. bit 42) may then be for the second subgroup of the first PO and so forth. If the number of subgroups is 1, the LSB+1 will map to the second PO. For example, the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasion index of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI. As such, for example, the shifted starting bit position is determined based on: DCI bit position maxDCI-2-7-Size-rl7 - (iP0 -K + iSG), where maxDCI-2-7-Size-rl7= total number of bits of the DCI; iP0 = paging occasion index of the UE (based on the equation in 38.213); K = N$° the number of subgroups per PO; and iSG = subgroup index of the UE . In some examples, the UE may not monitor paging if the PEI indicates in the spare bit that the UE does not need to monitor paging. In some examples, the UE monitors paging based on a power consumption measurement of the UE, since PDCCH monitoring may consumes more power than an RRC Idle / Inactive UE will consume in sleep / inactive state. If the PEI indicates in the spare bit that the UE shall monitor the paging, while the legacy bits does not indicate the UE shall monitor the paging, the UE may nevertheless monitors paging. Example Apparatus FIG. 10 shows an apparatus according to some example embodiments, which may comprise the user terminal 100. The user equipment may be, for example a smartphone, or other terminal device. The apparatus may be configured to perform the operations described herein, for example operations described with reference to any disclosed process. The apparatus comprises at least one processor 102 and at least one memory 104 directly or closely connected to the processor. The memory 104 includes at least one random access memory (RAM) and at least one read-only memory (ROM). Computer program code (software) 105 is stored in the ROM. The apparatus may be connected to a transmitter (TX) and a receiver (RX). The apparatus may, optionally, be connected with a user interface (UI) for instructing the apparatus and / or for outputting data. The at least one processor 102, with the at least one memory 104 and the computer program code 105 are arranged to cause the apparatus to at least perform at least the method according to any preceding process, for example as disclosed in relation to the flow diagrams and message sequences of FIGS. 3 to 5, 7 to 9 and related features thereof. FIG. 11 shows a non-transitory media 110 according to some embodiments. The non-transitory media 150 is a computer readable storage medium. It may be e.g. a CD, a DVD, a USB stick, a blue ray disk, etc. The non-transitory media 150 stores computer program code, causing an apparatus to perform the method of any preceding process for example as disclosed in relation to the flow diagrams and related features thereof. Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and / or protocols and / or methods may be different, as long as they provide a corresponding functionality. For example, embodiments may be deployed in 2G / 3G / 4G / 5G networks and further generations of 3GPP but also in non-3GPP radio networks such as WiFi. A memory may be volatile or non-volatile. It may be e.g. a RAM, a SRAM, a flash memory, a FPGA block ram, a DCD, a CD, a USB stick, and a blue ray disk. If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware. It does not necessarily mean that they are based on different software. That is, each of the entities described in the present description may be based on different software, or some or all of the entities may be based on the same software. Each of the entities described in the present description may be embodied in the cloud. Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Some embodiments may be implemented in the cloud. It is to be understood that what is described above is what is presently considered the preferred embodiments. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope as defined by the appended claims.

Claims

1. A first apparatus in a mobile communications system comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:receive, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI;receive, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus;determine whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions;if at least one of the one or more conditions are satisfied, determine the first at least one bit of the DCI based on the shifted starting bit position; and determine whether to monitor a paging occasion based, at least in part, on the first indication.

2. The first apparatus as claimed in claim 1, wherein at least one of the one or more conditions are based on one or more of the po-NumPerPEI, a number of subgroups of user equipment (UE) associated with a paging occasion, a number of used bits in the DCI and / or a number of spare bits in the DCI.

3. The first apparatus as claimed in claim 1 or 2, wherein at least one of the one or more conditions are satisfied if the po-NumPerPEI is less than or equal to a first threshold.

4. The first apparatus as claimed in claim 3, wherein the first threshold is equal to four.

5. The first apparatus as claimed in any one of the preceding claims, wherein at least one of the one or more conditions is based on a product of the po-NumPerPEI and the number of subgroups of UE associated with a paging occasion.

6. The first apparatus as claimed in any one of the preceding claims, wherein at least one of the one or more conditions is based on a value of a number of paging occasions per paging frame (Ns).

7. The first apparatus as claimed in claim 6, wherein at least one of the one or more conditions is satisfied if the value of the number of paging occasions per paging frame (Ns) is less than or equal to two.

8. The first apparatus as claimed in any one of the preceding claims, wherein at least one of the one or more conditions is based on a value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion.

9. The first apparatus as claimed in claim 8, wherein at least one of the one or more conditions is satisfied if the value of a sum of a number of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion is less than or equal to four.

10. The first apparatus as claimed in any one of the preceding claims, wherein at least one of the one or more conditions is based on a product of a value of a number of paging occasions per paging frame (Ns) and a value of a sum of core network (CN) controlled subgroups per paging occasion and a number of user equipment identity (UE ID) controlled subgroups per paging occasion.

11. The first apparatus as claimed in claim 10, wherein at least one of the one or more conditions is satisfied if the value of the product is less than or equal to sixteen.

12. The first apparatus as claimed in any of claims 2 to 11, wherein at least one of the one or more conditions is satisfied if the number of spare bits in the DCI is greater than or equal to sixteen.

13. The first apparatus as claimed in any one of the preceding claims, wherein the one or more conditions are satisfied if a second indication is received from the second apparatus indicating to determine the first at least one bit based on the shifted starting bit position.

14. The first apparatus as claimed in any one of the preceding claims, wherein the instructions further cause the first apparatus to apply an offset value to the firststarting bit position for determining the shifted starting bit position if one or more of conditions are satisfied.

15. The first apparatus as claimed in claim 14, wherein the instructions further cause the first apparatus to receive the offset value from the second apparatus.

16. The first apparatus as claimed in claim 14, wherein the instructions further cause the first apparatus to calculate the offset value based, at least in part, on a number of used bits in the DCI and / or a number of spare bits in the DCI.

17. The first apparatus as claimed in claim 16, wherein the first apparatus calculates the offset value based on information comprised in a system information block (SIB), comprising one or more of a physical control channel configuration (PCCH-Config) information element, a number of subgroups per paging occasion, a number of subgroups per user equipment (UE) identity, and / or tracking reference signal availability indication.

18. The first apparatus as claimed in any one of claims 16 or 17, wherein the instructions further cause the first apparatus to calculate the number of used bits based on:k = ns * (subgroupsNumPerPO-rl7 + subgroupsNumForUEID-rl7) + (indBitID+\) wherek=number of used bitsns= PCCH-Config information element;subgroupsNumPerPO-rl7 = number of subgroups per paging occasion;subgroupsNumForUEID-rl7 = number of subgroups per user equipment UE identity; andindBitID= tracking reference signal (TRS) availability indication.

19. The first apparatus as claimed in claim 18, wherein the offset value is equal to k+1.

20. The first apparatus as claimed in any one of claims 1 to 13, wherein the instructions further cause the first apparatus to determine the shifted starting bit position to be based on a least significant bit of the DCI.

21. A first apparatus as claimed in claim 20, wherein the shifted starting bit position for the first apparatus is based on a mapping of an increasing paging occasionindex of the first apparatus and / or subgroup index of the first apparatus in the order of increasing significant bits of the DCI.

22. A first apparatus as claimed in any one of claims 20 or 21, wherein the shifted starting bit position is determined based on:maxDCI-2-7-Size-rl7 — (iP0 ■ K + iSG), wheremaxDCI-2-7-Size-rl7= total number of bits of the DCI;iP0 = paging occasion index of the UE;K = N$° the number of subgroups per PO; andiSG = subgroup index of the UE.

23. A first apparatus according to any preceding claim, wherein the first apparatus is a user equipment.

24. The first apparatus as claimed in any one of the preceding claims, wherein said determining whether to monitor a paging occasion is based on the first indication.

25. A method, performed at a first apparatus of a mobile communications device, the method comprising:receiving, from a second apparatus, a Paging Early Indication (PEI) configuration, wherein the PEI configuration comprises a number (po-NumPerPEI) of paging occasions (PO) to be associated with one PEI;receiving, from the second apparatus, a downlink control information (DCI) comprising a PEI message, wherein the PEI message comprises a first indication of whether a paging occasion is to be monitored by the first apparatus;determining whether a first at least one bit of the DCI comprising the first indication is to be determined based on a first starting bit position or a shifted starting bit position based on one or more conditions;determining the first at least one bit of the PEI message based on the shifted starting bit position; anddetermining whether to monitor a paging occasion based, at least in part, on the first indication.IntellectualPropertyOfficeApplication GB2501762.5Search report under Section 17 of the Patents Act 1977Date search completed: 25 July 2025Claims searched: 1-25International classificationSubclass and subgroup Valid from H04W68 / 00 01 / 01 / 2009 H04W68 / 02 01 / 01 / 2009 H04W72 / 23 01 / 01 / 2023 H04W72 / 232 01 / 01 / 2023Field of searchWorldwide search of patent documents classified in the following areas of the IPC:H04WDatabases used in the preparation of this search report:SEARCH-NPL; SEARCH-PATENT; XP3GPPDocuments considered to be relevantPatent literatureCategory Relevant Document of relevanceclaimsX 1-3, 5-6, 14-15, 20, 23-25 US 2024 / 0422734 A1 ZHOU et al., See particularly para 0154-158, para 0181-0183 ¶ 0252 X 1-2, 6-7, 24-25 US 2024 / 0349239 A1 YANG et al., See particularly: para 0046, 0051-0053 X 1-2, 13, 23 25 US 2024 / 0334393 A1 HWANG et al., See particularly para: 0183, 0244-0245Non-patent literatureCategory Relevant claims Document of relevanceCategoriesLetter or DescriptionsymbolX Document indicating lack of novelty or inventive step.Y Document indicating lack of inventive step, if combined with anotherdocument of the same category.& Member of the same patent family. A Document indicating technological background. P Document published on or after the priority date but before the fling date of the present application. E Earlier application published on or after the filing date of the present application.

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