(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(10) International Publication Number
`WO 2018/126731 Al
`
`> a
`
`WIPOIPCT
`
`(19) World Intellectual Property
`Organization
`International Bureau
`
`(43) International Publication Date
`12 July 2018 (12.07.2018)
`
`(51) International Patent Classification:
`HO4L 29/06 (2006.01)
`HO04W 72/12 (2009.01)
`
`(74) Agent: ZHONGZI LAW OFFICE; 7F, New Era Building,
`26 Pinganli Xidajie, Xicheng District, Beijing 100034 (CN).
`
`(21) International Application Number:
`PCT/CN2017/101576
`
`(22) International Filing Date:
`13 September 2017 (13.09.2017)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`(30) Priority Data:
`PCT/CN2017/070130
`
`English
`
`English
`
`04 January 2017 (04.01.2017)
`
`CN
`
`(81) Designated States (unless otherwise indicated, for every
`kind of national protection available): AE, AG, AL, AM,
`AO,AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ,
`CA,CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO,
`DZ, EC, EE, EG, ES, FIL, GB, GD, GE, GH, GM, GT, HN,
`HR,HU,ID,IL, IN,IR, IS, JO, JP, KE, KG, KH, KN, KP,
`KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME,
`MG, MK, MN, MW,MX, MY, MZ, NA, NG,NI, NO, NZ,
`OM,PA,PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA,
`SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN,
`TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
`
`(84) Designated States (unless otherwise indicated, for every
`(71) Applicant!©TELEFONAKTIEBOLAGET LM
`
`kind of regional protection available): ARIPO (BW, GH,
`ERICSSON (PUBL)[SE/SE]; S-164 83 Stockholm (SE).
`GM,KE, LR, LS, MW, MZ, NA, RW, SD,SL, ST, SZ, TZ,
`UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU,TJ,
`TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
`EE, ES, FI, FR, GB, GR, HR, HU,IE,IS, IT, LT, LU, LV,
`MC, MK, MT, NL, NO,PL, PT, RO, RS, SE, SI, SK, SM,
`TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW,
`KM, ML, MR, NE, SN, TD, TG).
`
`(72) Inventor; and
`(71) Applicant (for SC only): FAN, Rui [CN/CN]; No.5 Lize
`East Street, Chaoyang District, Beijing 100102 (CN).
`
`(72) Inventors: LIU, Jinhua; No.5 Lize East Street, Chaoyang
`District, Beijing 100102 (CN). FRENGER,Pal, Enskiftes-
`gatan 8, S-583 34 Linkdeping (SE).
`
`(54) Title: ON-DEMAND REQUEST FOR SYSTEM INFORMATION
`
`
`
`102
`
`104
`
`
`
`wo2018/126731AaIMITIMMIIUIINIATURACMUAA (57) Abstract: A method for requesting system information is proposed. The method may comprise transmitting a request for at least
`
`
`
`
`
` Transmit a request for at least one SIB group, each
`
`of which comprises one or moreSIBs, from a user
`terminal to a network node, where the one or more
`SIBs are grouped according to a feature of the one
`or more SIBs
`
`
`
` Receive one or more SIB groups from the network
`
`node, where the one or more SIB groups comprise
`the at least one SIB group
`
`Fig.1
`
`one system information block group, each of which comprises one or more system information blocks, from a user terminalto a network
`node. The one or more system information blocks may be grouped accordingto a feature of the one or more system information blocks.
`The method may further comprise receiving one or more system information block groups from the network node. The one or more
`system information block groups may comprise the at least one system information block group.
`
`[Continued on next page]
`
`

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`WO 2018/126731 A[IMMINENTA
`
`Published:
`
`— with international search report (Art. 21(3))
`
`

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`WO2018/126731
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`PCT/CN2017/101576
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`ON-DEMAND REQUEST FOR SYSTEM INFORMATION
`
`FIELD OF THE INVENTION
`
`[0001]
`
`The present disclosure generally relates to communications, and more
`
`specifically, relates to wireless communications.
`
`BACKGROUND
`
`[0002]
`
`In a communication network such as Long Term Evolution (LTE) system,
`
`system information (SI) is important as it can provide necessary information to a user
`
`terminal, such as a user equipment (UE) or a wireless device, for linking with the
`
`communication network. In new radio (NR), SI may beclassified into minimum SI
`
`and other SI. Minimum SI is the SI that a user terminal must read before it can know
`
`how to access the network. Other SI is the SI not within minimum SI. SI may be
`
`transmitted to the user terminal in a master information block (MIB) and/or a system
`
`information block (SIB). For example, minimum SI may correspond to MIB, SIB1
`
`and SIB2 in LTE. Other SI may correspond to those remaining SIBs. Since other SI is
`
`not necessary for a user terminal to access network,
`
`in order to achieve energy
`
`efficiency, it may be desirable that the SI may be requested on demand.
`
`SUMMARY
`
`[0003]
`
`This summary is provided to introduce a selection of concepts in a
`
`simplified form that are further described below in detailed description. This
`
`summary is not intended to identify key features or essential features of the claimed
`
`subject matter, nor is it intended to be usedto limit the scope of the claimed subject
`
`matter.
`
`[0004]
`
`The present disclosure proposes a solution of on-demand request for SI,
`
`which may enable a communication network to transmit or broadcast SI, such as
`
`1
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`other SI as mentioned previously, according to a request for the SI from a user
`
`terminal.
`
`[0005 |
`
`According to a first aspect of the present disclosure, there is provided a
`
`method for requesting SI, which may be performed at an apparatus such as a user
`
`terminal. The method may comprise transmitting a request for at least one SIB group,
`
`each of which comprises one or more SIBs, from a user terminal to a network node.
`
`The one or more SIBs may be groupedaccording to a feature of the one or more SIBs.
`
`The method may further comprise receiving one or more SIB groups from the
`
`network node. The one or more SIB groups may comprise the at least one SIB group.
`
`[0006]
`
`In an exemplary embodiment, the method according to the first aspect of
`
`the present disclosure may further comprise receiving notification information from
`
`the network node. For example, transmission of the at least one SIB group may be
`
`predefined or derived based at least partly on the notification information.
`
`[0007]
`
`In an exemplary embodiment, the method according to the first aspect of
`
`the present disclosure may further comprise receiving an indicator from the network
`
`node. The indicator may indicate at
`
`least one of: which SIB group is being
`
`transmitted from the network node, and which SIB group is scheduled to be
`
`transmitted from the network node.
`
`[0008]
`
`According to a second aspect of the present disclosure, there is provided
`
`an apparatus for requesting SI. The apparatus may comprise at least one processor
`
`and at
`
`least one memory comprising computer program code. The at least one
`
`memory and the computer program code may be configured to, with the at least one
`
`processor, cause the apparatusat least to perform any step of the method according to
`
`the first aspect of the present disclosure.
`
`[0009]
`
`According to a third aspect of the present disclosure, there is provided a
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`computer program product comprising a computer-readable medium bearing
`
`computer program codes embodied therein for use with a computer. The computer
`
`program codes may comprise code for performing any step of the method according
`
`to the first aspect of the present disclosure.
`
`[0010]
`
`According to a fourth aspect of the present disclosure, there is provided an
`
`apparatus for requesting SI. The apparatus may comprise a transmitting module and a
`
`receiving module. In accordance with some exemplary embodiments, the transmitting
`
`module may be operable to carry out at least the transmitting step of the method
`
`according to the first aspect of the present disclosure. The receiving module may be
`
`operable to carry out at least the receiving step of the method according to the first
`
`aspect of the present disclosure.
`
`[0011]
`
`In accordance with an exemplary embodiment,
`
`the transmission of the
`
`request may comprise transmitting a preamble for indicating the at least one SIB
`
`group.
`
`[0012]
`
`In accordance with an exemplary embodiment,
`
`the transmission of the
`
`request may comprise: selecting, from a plurality of preambles, a preamble associated
`
`with the at least one SIB group; and transmitting the request to the network node. The
`
`request may include the selected preamble.
`
`[0013]
`
`In accordance with an exemplary embodiment, the at least one SIB group
`
`may be indicated by transmission timing of the preamble.
`
`[0014]
`
`In accordance with an exemplary embodiment,
`
`the transmission of the
`
`request may comprise transmitting the request to the network node in accordance
`
`with a selected transmission timing associated with the at least one SIB group.
`
`[0015]
`
`According to a fifth aspect of the present disclosure, there is provided a
`
`method for transmission of SI, which may be performed at an apparatus such as a
`
`3
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`network node. The method may comprise receiving a request for at least one SIB
`
`group, each of which comprises one or more SIBs, from a user terminal to a network
`
`node. The one or more SIBs may be grouped according to a feature of the one or
`
`more SIBs. The method may further comprise transmitting one or more SIB groups
`
`from the network node. The one or more SIB groups may comprise the at least one
`
`SIB group.
`
`[0016]
`
`In accordance with an exemplary embodiment, the method according to
`
`the fifth aspect of the present disclosure may further comprise:
`
`transmitting
`
`notification information to the user terminal. For example, transmission of the at least
`
`one SIB group may bepredefined or derived basedat least partly on the notification
`
`information.
`
`[0017]
`
`In accordance with an exemplary embodiment, the method according to
`
`the fifth aspect of the present disclosure may further comprise transmitting an
`
`indicator from the network node. The indicator may indicate at least one of: which
`
`SIB group is being transmitted from the network node, and which SIB group is
`
`scheduled to be transmitted from the network node.
`
`[0018]
`
`According to a sixth aspect of the present disclosure, there is provided an
`
`apparatus for transmission of SI. The apparatus may comprise at least one processor
`
`and at
`
`least one memory comprising computer program code. The at least one
`
`memory and the computer program code may be configured to, with the at least one
`
`processor, cause the apparatus at least to perform any step of the method according to
`
`the fifth aspect of the present disclosure.
`
`[0019]
`
`According to a seventh aspect of the present disclosure, there is provided
`
`a computer program product comprising a computer-readable medium bearing
`
`computer program codes embodied therein for use with a computer. The computer
`
`program codes may comprise code for performing any step of the method according
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`to the fifth aspect of the present disclosure.
`
`[0020]
`
`According to an eighth aspect of the present disclosure, there is provided
`
`an apparatus for transmission of SI. The apparatus may comprise a receiving module
`
`and a transmitting module. In accordance with some exemplary embodiments, the
`
`receiving module may be operable to carry out at least the receiving step of the
`
`method according to the fifth aspect of the present disclosure. The transmitting
`
`module may be operable to carry out at least the transmitting step of the method
`
`according to the fifth aspect of the present disclosure.
`
`[0021]
`
`In accordance with an exemplary embodiment,
`
`the reception of the
`
`request may comprise receiving a preamble for indicating the at least one SIB group.
`
`[0022]
`
`In accordance with an exemplary embodiment,
`
`the reception of the
`
`request may comprise receiving the preamble which wasselected from a plurality of
`
`preambles. The selected preamble may be associated with the at least one SIB group.
`
`[0023]
`
`In accordance with an exemplary embodiment, the at least one SIB group
`
`may be indicated by transmission timing of the preamble.
`
`[0024]
`
`In accordance with an exemplary embodiment,
`
`the reception of the
`
`request may comprise receiving the request from the user terminal in accordance with
`
`a selected transmission timing associated with the at least one SIB group.
`
`[0025]
`
`In
`
`accordance with an
`
`exemplary embodiment,
`
`the notification
`
`information may be included in minimumSI.
`
`[0026]
`
`In
`
`accordance with an
`
`exemplary embodiment,
`
`the notification
`
`information may indicate a correspondence betweenall of preambles and SIB groups.
`
`[0027]
`
`In accordance with some exemplary embodiments, the feature of the one
`
`or more SIBs may comprise at least one of functionality and periodicity of the one or
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`more SIBs.
`
`[0028]
`
`In accordance with some exemplary embodiments, the request for the at
`
`least one SIB group may comprise a preamble for indicating the at least one SIB
`
`group. The at least one SIB group maybe indicated by or associated with a preamble
`
`sequence or the transmission timing of the preamble. For example, the indication of
`
`the at least one SIB group by the preamble may be predefined or derived based at
`
`least partly on the notification information from the network node.
`
`[0029]
`
`In accordance with some exemplary embodiments, the one or more SIB
`
`groups from the network node may further comprise at least another SIB group which
`
`is not requested by the user terminal.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0030]
`
`The disclosure itself, the preferable mode of use and further objectives are
`
`best understood by reference to the following detailed description of
`
`the
`
`embodiments when read in conjunction with the accompanying drawings, in which:
`
`[0031]
`
`Fig.1 is a flowchart illustrating a method for requesting SI according to an
`
`embodimentof the present disclosure;
`
`[0032]
`
`Fig.2 is a flowchart illustrating a method for transmission of SI according
`
`to another embodimentof the present disclosure;
`
`[0033]
`
`Fig.3 is a block diagram illustrating an apparatus according to an
`
`embodiment of the present disclosure; and
`
`[0034]
`
`Fig.4 is a block diagram illustrating another apparatus according to an
`
`embodiment of the present disclosure.
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`

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`DETAILED DESCRIPTION
`
`[0035]
`
`The embodiments of the present disclosure are described in detail with
`
`reference to the accompanying drawings. Reference throughoutthis specification to
`
`features, advantages, or similar language does not imply that all of the features and
`
`advantages that may be realized with the present disclosure should be or are in any
`
`single embodiment of the disclosure. Rather, language referring to the features and
`
`advantages is understood to meanthat a specific feature, advantage, or characteristic
`
`described in connection with an embodimentis included in at least one embodiment
`
`of the present disclosure. Furthermore,
`
`the described features, advantages, and
`
`characteristics of the disclosure may be combined in any suitable manner in one or
`
`more embodiments. One skilled in the relevant art will recognize that the disclosure
`
`may be practiced without one or more of the specific features or advantages of a
`
`particular embodiment. In other instances, additional features and advantages may be
`
`recognized in certain embodiments that may not be present in all embodiments of the
`
`disclosure.
`
`[0036]
`
`In a wireless network such as new radio (NR), SI may be broadcasted by a
`
`network node, such as a base station or a next generation Node B (gNB), in a cell to
`
`all user terminals monitoring the specific cell. It is important for a user terminal to
`
`maintain the required SI because otherwise it cannot interact with the network in an
`
`interoperable manner. As mentioned previously, minimum SI in NR correspondsto
`
`MIB, SIB1 and SIB2 in LTE. There are some assumptions about how to request other
`
`SI from the network. For example, some messages like MSGI and/or MSG3 may be
`
`used to carry a request for other SI.
`
`[0037]
`
`If using one preamble of MSGI to carry a request for all other SI, then it
`
`may result in unnecessary transmission of some undesired other SI. This is because
`
`there is quite a lot of other SI in the system and the network mayhaveto broadcastall
`
`other SI when it receives such preamble to request other SI. However, a user terminal
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`may not needall the other SI.
`
`[0038]
`
`If using MSG3 to request other SI, since there could be contention during
`
`a random access procedure, the network may not be able to detect MSG3 reliably in
`
`time. In addition, there are additional overhead and delay because more messagesare
`
`transmitted for requesting other SI.
`
`[0039]
`
`The present disclosure proposes a solution of on-demand requestfor SI. In
`
`the proposedsolution, one or more SIBs may beclassified into a SIB group according
`
`to their relevance or correlation. When a user terminal wants to request some specific
`
`SI,
`
`it can request from a network node a SIB group in which the specific SI is
`
`contained. Then, the network node can know which SIB group the user terminal
`
`actually needs, and broadcast the requested SIB group accordingly. In this way, the
`
`network node can transmit or broadcast the SI to the user terminal with more energy
`
`efficiency. On the other hand, transmission resources and energy also can be saved
`
`from the view point of the user terminal, since it does not need to send additional SI
`
`request if another user terminal has already sent a request for the same SI as required
`
`by the user terminal.
`
`[0040]
`
`Fig.1 is a flowchart illustrating a method for requesting SI according to an
`
`embodiment of the present disclosure. The method illustrated in Fig.l may be
`
`performed by an apparatus implemented at a user terminal or communicatively
`
`coupled to a user terminal. In accordance with the exemplary embodiment, the user
`
`terminal may comprise a UE, a mobile station, a wireless device, a personal digital
`
`assistant (PDA), a laptop computer, a tablet computer, a smart phone, a portable
`
`device, or any other user device being capable of participating in communication of a
`
`wireless network.
`
`[0041]
`
`According to the exemplary methodillustrated in Fig.1, a request for at
`
`least one SIB group, each of which comprises one or more SIBs, may be transmitted
`
`8
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`from a user terminal to a network node, as shown in block 102. In the exemplary
`
`embodiment,
`
`the one or more SIBs may be grouped or classified according to a
`
`feature of the one or more SIBs. It will be realized that the SI corresponding to the
`
`SIB mentioned here may comprise other SI than minimum SI]in the context of NR.It
`
`is noted that the terms of “SI” and “SIB” used herein and the exemplary illustration
`
`of grouping of one or more SIBs are not limited to NR and LTE. The proposed
`
`methods, apparatus and related products herein may also be applicable to other
`
`suitable network environments, although some exemplary embodimentsare described
`
`with respect to NR and LTE. As described previously, minimum SI correspondsto
`
`MIB, SIB1 and SIB2 in LTE, and accordingly other SI corresponds to SIB3 until
`
`SIB21. The feature of the one or more SIBs may be learned from the SIB definition
`
`in LTE. For example, the feature of the one or more SIBs may comprise at least one
`
`of functionality and periodicity of the SIBs. However, other suitable rules may also
`
`be expected to be applicable for learning more features of SIBs.
`
`[0042]
`
`Table 1 exemplarily shows the functional description of some SIBs in
`
`LTE. It can be seen from Table 1 that the SIBs carrying SI are not fully independent
`
`to each other. For example, SIB3 to SIB8 are all related to how to docell reselection,
`
`although each SIB has different responsibility. Therefore, SIB3 to SIB8 can be
`
`grouped together. For SIB10 to SIB12, these SIBs are all related to warning andalert.
`
`Therefore, SIB10 to SIB12 can be group together. For SIB18 to SIB19, the SIBs are
`
`both related to device-to-device (D2D) sidelink communication. Accordingly, SIB18
`
`to SIB19 can be grouped together. The remaining SIBs can be grouped together. Thus,
`
`the SIBs listed in Table 1 may be classified into four groups.
`
`Table 1
`
` SIB3
`
`Parameters required for intra-frequency, inter-frequency and I-RATcell
`re-selections
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`

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`WO2018/126731
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`SIB4
`SIB5
`SIB6
`SIB7
`SIB8
`
`cells (E-UTRA)
`i
`i
`cells (E-UTRA)
`ing
`Information regarding INTER-frequency neig
`Information for re-selection to INTER-RAT (UTRANcells)
`Information for re-selection to INTER-RAT (GERANcells)
`Information for re-selection to INTER-RAT (CDMA2000)
`
`ing
`
`SIBI0
`
`ETWS(Earthquake and Tsunami Warning System) information (Primary
`notification)
`ETWS(Earthquake and Tsunami Warning System) information (Secondary
`notification)
`SIB12_|Commercial Mobile Alert Service (CMAS) information.
`
`configuration information
`
`SIBII
`
`SIBI8
`
`SIB19
`
`Sidelink UE information procedure, sidelink communication related resource
`configuration information
`Sidelink UE information procedure, sidelink discovery related resource
`. .
`.
`
`[0043]
`
`It can be seen that different SIBs and the SI thereof may be grouped
`
`according to their functionalities. Optionally, the SIBs may be classified into more or
`
`less groups than four groups. For example, since the transmission of SIBs related to
`
`warning and alert is triggered by the network instead of by a user terminal, the SI
`
`associated with SIB10 to SIB12 does not need to be requested by the user terminalat
`
`all. Then in total there are three SIB groups to be requested. Other ways to group
`
`these SIBs are also possible. For example, the SIBs related to cell reselection may be
`
`classified into one group, while all others maybe classified into another group.
`
`[0044]
`
`Another feature of SIBs which may be used to classify the SIBs is
`
`periodicity. For example, SIBs with the sameor similar transmission periodicity may
`
`be grouped together. Use LTE SIB transmission periodicity as an example, where the
`
`SIBs each with periodicity of 80ms, 160ms, 320ms, 640ms, 1280ms, 2560ms and
`
`5120ms may be classified into seven SIB groups. Alternatively, the SIBs may be
`
`classified into three SIB groups with the first group comprising SIBs with
`
`periodicities of 80ms, 160ms, the second group comprising SIBs with periodicities of
`
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`320ms, 640ms, and the third group comprising SIBs with periodicities of 1280ms,
`
`2560ms, 5120ms. It will be realized that one or more SIBs maybeclassified into the
`
`desired number of groups according to the periodicity of SIBs.
`
`[0045]
`
`In accordance with the exemplary method illustrated in Fig.1,
`
`the
`
`transmission of the request for the at least one SIB group may comprise transmitting
`
`a preamblefor indicating the at least one SIB group.
`
`[0046]
`
`In an exemplary embodiment,
`
`the transmission of the request may
`
`comprise selecting, from a plurality of preambles, a preamble associated with the at
`
`least one SIB group; and transmitting the request to the network node. The request
`
`mayincludethe selected preamble.
`
`[0047]
`
`In an exemplary embodiment, the at least one SIB group maybe indicated
`
`by transmission timing of the preamble. Optionally, the transmission of the request
`
`may comprise transmitting the request to the network node in accordance with a
`
`selected transmission timing associated with the at least one SIB group.
`
`[0048]
`
`In an exemplary embodiment,
`
`the at
`
`least one SIB group may be
`
`associated with a preamble (also referred to as a sequence of the preamble or a
`
`preamble sequence for ease of description) or the selected transmission timing of the
`
`preamble. Thus, the user terminal can selectively request the required SIB group from
`
`the network node.
`
`[0049]
`
`In an exemplary embodiment, selective requests for SIB groups may be
`
`transmitted from the user terminal by using different preamble sequences, which may
`
`be differentiated by indexes of the preambles. One preamble sequence may
`
`correspond to a predetermined combination of SIB groups. Take 3 preambles as an
`
`example. In alternative I, preambles 1 to 3 may be used to indicate SIB groups | to 3,
`
`respectively, where SIB group 1 is related to cell reselection, SIB group 2 is related to
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`sidelink communication, and SIB group 3 comprises the remaining one or more SIBs.
`
`According to this alternative, a user terminal needing multiple SIB groups (for
`
`example, comprising SIB groups | and 2) may be required to send multiple SIB
`
`group requests (for example, comprising preambles | and 2) to a network node.
`
`[0050]
`
`It will be realized that the usage of multiple preambles can be in different
`
`ways. For example, in alternative II, preambles 1 to 3 may be usedto indicate SIB
`
`group 1, SIB groups 1+2, and SIB groups 1+2+3, respectively. According to this
`
`alternative, a user terminal can always select a corresponding preamble to get all
`
`desired SIB groups. Compared to alternative I, alternative I] may save the preamble
`
`resource/transmission but the probability to transmit the undesired SI is higher than
`
`alternative I.
`
`[0051]
`
`Thus, when SIB groups in the network are indicated by using different
`
`preambles, the user terminal can send the corresponding preamble to the network
`
`node if the user terminal wants to request SI from at least one of the SIB groups.
`
`When the network node detects such preamble,
`
`it can therefore only transmit or
`
`broadcast SI within the indicated SIB groups according to the detected preamble.
`
`[0052]
`
`In accordance with the exemplary method illustrated in Fig.1, the user
`
`terminal may receive notification information transmitted from the network node. In
`
`this case, transmission of the at least one SIB group may be predefined or derived
`
`based at least partly on the notification information. Optionally,
`
`the notification
`
`information may be included in minimumSI.
`
`[0053]
`
`In an exemplary embodiment, the notification information may indicate a
`
`correspondence between all of preambles
`
`and SIB_
`
`groups. Optionally,
`
`the
`
`correspondence between the at least one SIB group and the associated preamble or
`
`the indication of the at least one SIB group by the preamble may be predefined or
`
`derived based at least partly on the notification information from the network node.
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`For example, the preambles which are used to request on-demand transmission of SI
`
`carried by one or more SIBs can be predefined according to a specified rule known
`
`by the user terminal and the network node.
`
`[0054]
`
`In an exemplary embodiment, if the correspondence between preambles
`
`and SIB groups is informed in minimum SI, the minimum SI can indicate only one
`
`preamble for one SIB group, while there is a specified rule for the user terminal to
`
`derive other preambles for other SIB groups. For example, it is assumed that the
`
`specified rule is that all the preambles for requesting SIB groups are with consecutive
`
`indexes, and each preamble with an index increased by one indicates one more SIB
`
`group. As such, for alternative II as mentioned previously, if it is informed in the
`
`minimum SI that a preamble with index ‘n’
`
`is used to indicate SIB group 1, then
`
`according to the specified rule, the user terminal may know that a preamble with
`
`index ‘n+l’ is used to indicate SIB groups 1+2, and a preamble with index ‘n+2’ is
`
`used to indicate SIB groups 1+2+3. It will be appreciated that other suitable rules also
`
`may be applicable to determine preambles for selective request and transmission of
`
`SI. For example, the preambles for requesting SIB groups may be with inconsecutive
`
`indexes, and/or the correspondence between all of preambles and SIB groups may be
`
`informed in the minimum SI from the network node.
`
`[0055]
`
`In another exemplary embodiment, selective requests for SIB groups may
`
`be transmitted from the user terminal by using different preamble timing. In this
`
`embodiment, only one preamble may be used to request SIB group transmission from
`
`the network node, but the timing at which the preamble is sent can be utilized to
`
`determine which SIB groupis requested. Therefore, compared with the embodiment
`
`where different preambles are used to indicate multiple SIB groups, using different
`
`transmission timing of one preamble to indicate multiple SIB groups may save
`
`transmission resources.
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`[0056]
`
`Assuming there are three SIB groups,
`
`including SIB group A with
`
`periodicities of 80ms, 160ms, SIB group B with periodicities of 320ms, 640ms, and
`
`SIB group C with periodicities of 1280ms, 2560ms, 5120ms. The respective
`
`minimum periodicities of SIB groups A, B and C are 80ms, 320ms and 1280ms,
`
`respectively. Then the timing at which a SIB group is requested by sending a
`
`preamble determines which SIB groupis requested. In an exemplary embodiment, the
`
`requested SIB group may be determined according to whether
`
`the frame
`
`corresponding to the preamble sent by the user terminal has an integer multiple
`
`period of the minimum periodicity of the SIB group. Asa furtherrule, if the period of
`
`that frame is an integer multiple of the minimum periodicities of several SIB groups,
`
`then the SIB group with the largest periodicity (or alternatively the SIB group with
`
`the smallest periodicity) may be determined as the requested SIB group. In another
`
`exemplary embodiment, the requested SIB group may be determinedaccording to the
`
`frame corresponding to the preamble sent by the user terminal and the latest next
`
`frame in which SI can be transmitted or broadcasted. In this embodiment, the frame
`
`corresponding to the preamble may have a period whichis not an integer multiple of
`
`the minimum periodicity of the SIB group.
`
`[0057]
`
`Use the LTE frame as an example, where the frame length is 10ms. If the
`
`number of the frame corresponding to the preamble is 24, then the period of the
`
`frame is 240ms, whichis an integer multiple of the minimum periodicity 80ms of SIB
`
`group A. This meansthat the user terminal wants to request SIB group A. Similarly,
`
`if the number of the frame corresponding to the preamble is 96, then the period of the
`
`frame is 960ms, whichis an integer multiple of the minimum periodicity 80ms of SIB
`
`group A and the minimum periodicity 320ms of SIB group B. This means that the
`
`user terminal wants to request both SIB group A and SIB group B but not SIB group
`
`C. Or as the further rule, it is SIB group B that is requested instead of SIB group A
`
`plus B, because the minimum periodicity of SIB group B is larger than that of SIB
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`group A. Alternatively, if the frame number corresponding to the preamble is 22, then
`
`the numberof the latest next frame to transmit or broadcast SI is 24, according to a
`
`predefined criterion. Since the period of this latest next frame is 240ms, whichis an
`
`integer multiple of the minimum periodicity of SIB group A, this could mean that the
`
`user terminal wants to request just SIB group A.
`
`[0058]
`
`Thus, when the user terminal wants to request a certain SIB group, it can
`
`send a preamble as a request to the network node at the specific timing or frame.
`
`When the network node detects this preamble, it can determine which SIB group the
`
`user terminal wants to request, according to the transmission timing of the preamble.
`
`Accordingly,
`
`the network node can only transmit or broadcast SI within the
`
`corresponding SIB group in the network. This can eliminate unnecessary SI
`
`transmissions in the network.
`
`[0059]
`
`Referring back to Fig.1, the user terminal may receive one or more SIB
`
`groups from the network node, as shown in block 104. The one or more SIB groups
`
`may comprise the at least one SIB group requested by the user terminal in block 102.
`
`Optionally, the one or more SIB groups may further comprise at least another SIB
`
`group which is not requested by the user terminal. For example, preamble 3 is used to
`
`indicate SIB groups 1+2+3, as described previously in alternative II. If the user
`
`terminal wants to obtain SI within SIB group 1, then the user terminal may also
`
`obtain SIB groups 2 and 3 in addition to SIB group 1, when using preamble 3 to
`
`request SIB group | from the network node. Apparently, SIB groups 2 and 3 are not
`
`actually needed by the user terminal. In another example, since the network node may
`
`transmit or broadcast multiple SIB groups requested by different user terminals in the
`
`network, the user terminal may receive one or more SIB groups requested by other
`
`user terminals.
`
`[0060]
`
`Fig.2 is a flowchart illustrating a method for transmission of SI according
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`to another embodiment of the