as) United States
`a2) Patent Application Publication 10) Pub. No.: US 2010/0167746 Al
` Leeet al. (43) Pub. Date: Jul. 1, 2010
`
`
`
`US 20100167746A1
`
`(54) METHOD OF TRANSMITTING/RECEIVING
`LTE SYSTEM INFORMATIONIN A
`WIRELESS COMMUNICATION SYSTEM
`
`(76)
`
`Inventors:
`
`Young-Dae Lee, Gyeonggi-Do
`(KR); Sung-Duck Chun,
`Gyeonggi-Do (KR); Myung-Cheul
`Jung, Seoul (KR); Sung-Jun Park,
`Gyeonggi-Do (KR); Patrick
`Fischer, Bourg la Reine (FR)
`
`Correspondence Address:
`LEE, HONG, DEGERMAN, KANG & WAIMEY
`660 S. FIGUEROA STREET,Suite 2300
`LOS ANGELES, CA 90017 (US)
`
`(21) Appl. No.:
`
`12/293,805
`
`(22) PCT Filed:
`
`Mar. 19, 2007
`
`(86) PCT No.:
`
`PCT/KR07/01335
`
`§ 371 (©)Q),
`(2), (4) Date:
`Sep. 19, 2008
`Related U.S. Application Data
`(60) Provisional application No. 60/784,680,filed on Mar.
`21, 2006.
`
`+
`as
`:
`:
`Publication Classification
`
`(51)
`
`Int. Cl.
`HO4W 72/00
`(2009.01)
`HO4K 1/10
`(2006.01)
`.
`(52) US. CM. coceccccccccssessesessessseessessseeens 455/450; 375/260
`(57)
`ABSTRACT
`In a wireless mobile communications system, the system
`information is groupedorclassified in different types accord-
`ing to the characteristics of the system information, and the
`system information is transmitted to channels with specific
`functions that allow the optimization of the resource usage
`and the reception by the User Equipment (UE).
`
`aGW Control Plane
`
`
`
`SAE Bearer
`Control
`
`MM Entity
`
`
`
`aGW User Plane
`
`
`
`UserPlane apes
`
`
`
`
`1
`
`APPLE 1004
`
`
`
`U0 =x
`
`w a
`
`RB Controlay
`
`ONERHRORECARRATFETEENEHNNERARERARAeAEEEREREOOe
`
`
`Inter Cell RRM
`
`Connection
`Mobility Cont
`
`Radio
`Admission
`Control
`
`eNB
`Measurement
`Configuration&
`Provision
`
`Dynamic
`Resource
`Allocation
`I
`(Scheduler)
`
`
`RRC
`
`
`
`
`
`
`
`
`
`
`PDCP
`
`
`
`1
`
`APPLE 1004
`
`

`

`Patent Application Publication
`
`Jul. 1,2010 Sheet 1 of 3
`
`US 2010/0167746 Al
`
`[Fig. 1]
`
`eNB
`
`
`
`
`
`;
`
`Inter Cell RRM
`
`Connection
`Mobility Cont
`
`RB Control
`
`Radio
`Admission
`Control
`
`
`eNB
`Measurement
`Configuration&
`Provision
`
`
`
`Dynamic
`Resource
`Allocation
`
`(Schedule
`
`RRC
`
`RLC
`
`
`
`[Fig. 2]
`
`
`
`
`
` “IFFTop}ps |p| Celle LY
`
`
`
`‘aol
`DFT |
`:
`<d for om
`.
`Modulation SP | Mapping
`cel
`only |
`oat
`
`1 sub -frame
`
`OFDM symbol
`
`
`
`|
`
`t|
`
`
`
`
`Fig. 3]
`
`Sub -
`
`frame with short CP
`
`Sub- frame with long CP
`
`
`
`
`
`aGW Controi Plane
`
`
`SAE Bearer
`Control
`
`
`
`
`
`MM Entity
`
`aGW UserPiane
`
`COLaem
`
`\
`
`PDCP
`
`|
`
`:
`
`ae
`
`internet
`
`)
`J
`
`MAG
`
`
`
`“ a
`PHY
`
`User Plane
`co ee
`
`
`
`PAPEOeHNOROEREROATORERFORTERSKEWAWATEEHEHEENRESOER
`
`
`
` |
`
`
`
`
`
`
`
`
`
`2
`
`

`

`Patent Application Publication
`
`Jul. 1,2010 Sheet 2 of 3
`
`US 2010/0167746 Al
`
`[Fig. 4]
`
`Subcarriers
`
`(VVVV¥WWWVVFV4
`
`
`Frequency
`
`[Fig. 5]
`
`CeliA
`Cp)
`
`Cell B
`©)
`\
`
`
`
`UE A
`
`Fig. 6]
`
`
`
`BCH
`
`UE is receiving one part of the
`10 MHz of the 20 MHz spectrum
`
`3
`
`

`

`Patent Application Publication
`
`Jul. 1,2010 Sheet 3 of 3
`
`US 2010/0167746 Al
`
`Fig. 7]
`
`
`
`
`
`“a
`vs
`
`i
`CI
`|
`:
`
`st alternative move BCHto the upper 10 MHzor
`to the lower 10 MHz part
`
`VEis receiving one part of the
`10 MHzof the 20 MHz spectrum
`
`\ 24 alternativesplittheBCIin
`
`two separately decodable blocks
`such the UE can decode the block.
`Theimpactis that the block is smaller,
`hencethe efficiency is smaller
`
`
`
`[Fig. 8]
`
`SCH
`
`a
`
`
`PrimaryBCH
`
`T
`—S
`
`Secondary BCH
`
`4
`
`

`

`US 2010/0167746 Al
`
`Jul. 1, 2010
`
`METHOD OF TRANSMITTING/RECEIVING
`LTE SYSTEM INFORMATIONIN A
`WIRELESS COMMUNICATION SYSTEM
`
`[0001] This application claimspriority to U.S. Patent Pro-
`visional Application No. 60/784,680,filed on Mar. 21, 2006,
`whichis incorporated herein by reference.
`
`DISCLOSURE OF INVENTION
`
`Technical Solution
`
`[0002] This disclosure relates to a wireless communication
`system, moreparticularly, to a methodoftransmitting/receiv-
`ing LTE system information in a wireless communication
`system.
`In the related art, the system information is mainly
`[0003]
`broadcasted through a channel[i.e., P-CCPCH channel] hav-
`ing a constant data rate in the Universal Mobile Telecommu-
`nications System (UMTS). This implies that the transmission
`of system information has static characteristic. When the
`system information is transmitted through the fixed radio
`resources, the network cannot have flexibility for scheduling
`of data transmission so that it becomes hard to be applicable
`to the change ofradio environment. As such,the transmission
`of system information is not coordinated between different
`cells. Therefore, in the case of OFDM,using only onestatic
`channelfor the transmission of system information would not
`allow to optimize the transmissionor reception of the system
`information.
`
`[0004] This disclosure has been developed in orderto solve
`the above described problemsofthe related art. As a result,
`this disclosure provides a method of transmitting and/or
`receiving the system information on an OFDMairinterface in
`an efficient manner.
`
`[0005] Accordingly, this disclosure is directed to a method
`of transmitting and/ or receiving the system information in a
`mobile communication system that substantially obviates one
`or more problemsdueto limitations and disadvantages of the
`related art.
`
`FIG. 3 shows an exemplary structure of an OFDM
`[0010]
`sub-framestructure.
`
`FIG. 4 shows an exemplary diagram illustrating
`[0011]
`sub-catriers in transmission bandwidth.
`
`FIG. 5 shows an exemplary diagram illustrating a
`[0012]
`reception of several cells by a
`[0013] UE.
`[0014]
`FIG. 6 shows an exemplary diagram illustrating 10
`MHz UEin 20 MHzspectrum in accordance with a present
`disclosure.
`
`FIG. 7 shows an exemplary diagram illustrating a
`[0015]
`reception of the BCH in the case of 20 MHz system band-
`width in accordance with a present disclosure.
`[0016]
`FIG. 8 shows an exemplary diagram illustrating a
`primary and a secondary BCHin accordance with a present
`disclosure.
`
`[0017] One aspect of this disclosure is the recognition by
`the present inventors regarding the problems and drawbacks
`ofthe related art described above and explained in more detail
`hereafter. Based upon such recognition, the features of this
`disclosure have been developed.
`[0018] Although this disclosure is shown to be imple-
`mented in a mobile communication system, such as a UMTS
`developed under 3GPPspecifications, this disclosure can also
`be applied to other communication systems operating in con-
`formity with different standards and specifications.
`[0019]
`FIG. 1 is a block diagram of a networkstructure of
`an E-UMTS (Evolved-Universal Mobile Telecommunica-
`tions System) to which technical features of this disclosure
`maybe applied. Recently, an initiative has been started in the
`scope of the 3GPP (3Generation Partnership Project).
`project to standardize a newair interface for a mobile com-
`munication system compared to the second generation air
`interface (as known under the name of GSM based on TDM
`(Time division multiplexing) and FDM (Frequencydivision
`multiplexing)), and the 3”” generation air interface (as known
`under the name UMTSandbased on CDMA (Code division
`multiplexing)). The new air interface that is currently dis-
`cussed as LTE (Long Term Evolution) is based on OFDM
`(Orthogonal
`Frequency Division Multiplexing). The
`E-UMTSis a system evolving from the conventional UMTS
`and its basic standardization is currently handled by the
`3GPP.
`
`[0020] Referring to FIG. 1, an E-UMTSnetwork includes a
`user equipment(hereinafter abbreviated ‘UE’), a basestation
`(hereinafter named ‘eNode B’ or ‘eNB’) and an access gate-
`way(hereinafter abbreviated ‘aGW’) connected to an exter-
`nal network by being located at an end of the E-UMTSnet-
`work. The eNB and the aGW are connected via an interface
`
`To implementat least the above feature in whole or
`[0006]
`in parts, this disclosure may provide a method ofbroadcasting
`or receiving the system information in a mobile communica-
`tion system,the system information is groupedor classifiedin
`different types according to the characteristics of the system
`information, and then the system information is transmitted
`or received via different types of channels with specific func-
`tionsthatallow the optimization ofthe resource usage and the
`reception by the User Equipment (UE), wherein the different
`called S1. The aGW maybeclassified into a part for handling
`types of channels maybeastatically scheduled channel and/
`usertraffic and a part for handling controltraffic. A first aGW
`or a flexibly scheduled channel.
`for processing new user traffic may communicate with a
`[0007] Additional features of this disclosure will be set
`second AGW for processing control traffic via a new inter-
`forth in part in the description which follows andin part will
`face. A first interface for transmitting usertraffic or a second
`become apparentto those having ordinary skill in the art upon
`interface for transmitting control
`traffic may be located
`examinationofthe following or maybe learned from practice
`between several eNBs. Here, the eNB may include at least
`one cell.
`ofthis disclosure. The objectives and other advantagesofthis
`disclosure mayberealized and attained by the structure par-
`ticularly pointed out in the written description and claims
`hereof as well as the appended drawings.
`[0008] FIG.1is anexemplary diagram illustrating protocol
`architecture of the E-UTRAN.
`
`FIG. 2 shows an exemplary structure of an OFDM
`[0009]
`transmission.
`
`[0021] The eNB may perform functions of selection for
`Access gateway (AGW), a routing toward the AGW during a
`Radio Resource Control (RRC)activation, a scheduling and
`transmitting of paging messages, a scheduling and transmit-
`ting of Broadcast Channel (BCCH)information, a dynamic
`allocation of resources to UEs in both a uplink and a down-
`link, a configuration and provision of eNB measurements, a
`
`5
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`

`

`US 2010/0167746 Al
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`Jul. 1, 2010
`
`radio bearer control, a radio admission control (RAC), and a
`connection mobility control in LTE_ACTIVEstate.
`[0022] The functions located in the eNB will bebriefly
`described as follows: the function of ‘Inter Cell RRM’ may
`handle the use of the available resources between different
`
`cells and eNBs. The function of ‘Connection and Mobility
`Control’ may control the maintenance of the connection
`between the network and a relocation of the UE context in
`
`case of mobility. The function of ‘RB Control’ may maintain
`radio bearers (RBs) between the UE and the eNB. Theradio
`bearer (RB)is a service provided by the secondlayer (L2) for
`data transmission between the terminal and the UTRAN.In
`
`general, the setting of the RB refers to the process of stipu-
`lating the characteristics of a protocol layer and a channel
`required for providing a specific data service, and setting the
`respective detailed parameters and operation methods. The
`function of ‘Radio Admission Control’ may provide for ser-
`vices with specific Quality of Service (QoS) requirements to
`ensure the availability of certain resources. As such, it may be
`necessary to decide for a requested radio service, when the
`required resourcesare available and the admission would not
`endangerthe availability of resources for already admitted
`services. The function of ‘eNB Measurement Configuration
`and Provision’ may provide the eNB to configure measure-
`ments in the UE andto provide it with information for per-
`forming these measurements. The function of ‘Dynamic
`Resource Allocation’ may provide the eNB to allocate the
`available resources dynamically for the different UEs which
`are served by the eNB. The radio resource control (RRC)
`layer may be located at the lowest portion of the third layer
`(L3) is only defined in the control plane and may control
`logical channels, transport channels and the physical chan-
`nels in relation to the configuration, reconfiguration, and
`release or cancellation of the radio bearers (RBs). Addition-
`ally the RRC may handle user mobility within the RAN,and
`additional services, e.g. location services. The RLC layer
`mayperform segmentation, concatenation in sequencedeliv-
`ery, repetition, error recovery and other functions in order to
`exchange Service Data Units (SDUs) between the eNB an the
`UEentity. The RLC layer may create Protocol Data Units
`(PDUs) that use a sequence number in order to allow the
`re-ordering, and the detection of lost or re-transmitted PDUs.
`The MAClayer may control the access to the transmission
`resources. The physical layer may provide an information
`transfer service to an upper layer by using various radio
`transmission techniques.
`[0023]
`Inthe E-UTRAN, the AGW mayperform functions
`of a paging origination, a LTE-IDLE state management, a
`ciphering of the user plane, supporting a Packet Data Con-
`vergence Protocol (PDCP) function, a System Architecture
`Evolution (SAE)bearer control, and a ciphering andintegrity
`protection of Non-Access Stratum (NAS)signalling.
`[0024] The functions located in the aGW will be briefly
`described as follows: the function of ‘SAE Bearer Control’
`
`may provide the UTRANto construct and to maintain a radio
`access bearer (RAB) for communication between the termi-
`nal and the core network. The core network may request
`end-to-end quality of service (QoS) requirements from the
`RAB, and the RAB may support the QoS requirements the
`core network has set. As such, by constructing and maintain-
`ing the RAB, the UTRAN maysatisfy the end-to-end QoS
`requirements. The function of ‘The Mobility Management
`Entity’ may handle access data from the home database, and
`may maintain subscription data(e.g. allowed areas, etc.), may
`
`accept/deny UEs location in IDLE, may store UEs location
`(TA)
`in IDLE, may handle user identity confidentiality
`(TMSJ) and so on. The Packed Data Convergence Protocol
`(PDCP) layer may be located above the RLC layer. The PDCP
`layer may be usedto transmit network protocol data, such as
`the IPv4 or IPv6,efficiently on a radio interface with a rela-
`tively small bandwidth. The PDCP layer may reduce unnec-
`essary control information used in a wired network, and may
`perform a function called header compression.In addition the
`PDCPlayer may provide ciphering and integrity protection
`for the transmitted data.
`
`[0025] Transport channels may be introducedin the wire-
`less communications system in order to allow different types
`of quality of service for the transmission of information. The
`transport channel may provide a service to the MAClayer and
`may connect to the physical layer. The different transport
`channels may be introduced in the LTE as followings: first,
`types of downlink transport channels can be described as
`follows; 1. Broadcast Channel (BCH)is characterised by: a)
`fixed, pre-defined transport format, and b) requirementto be
`broadcast in the entire coverage area of the cell 2. Downlink
`Shared Channel (DL-SCH)is characterised by: a) support for
`HARQ,b) support for dynamiclink adaptation by varying the
`modulation, coding and transmit power, c) possibility to be
`broadcast in the entire cell, d) possibility to use beamforming,
`e) support for both dynamic and semi-static resource alloca-
`tion, support for UE discontinuous reception (DRX) to enable
`UE power saving, and g) support for MBMStransmission
`(FFS) 3. Paging Channel (PCH) is characterised by: a) sup-
`port for UE discontinuous reception (DRX) to enable UE
`powersaving (DRX cycle is indicated by the network to the
`UE), b) requirement to be broadcast in the entire coverage
`area of the cell, and c) mappedto physical resources which
`can be used dynamically also for traffic or other control
`channels, and 4. Multicast Channel (MCH)is characterised
`by: a) requirementto be broadcast in the entire coverage area
`of the cell, b) support for combining of MBMStransmission
`on multiple cells (the exact combining schemeis FFS), and c)
`support for semi-static resource allocation (e.g., with a time
`frameof a long cyclic prefix). Also, types of uplink transport
`channels can be described as follows; 1. Uplink Shared Chan-
`nel (UL-SCH) characterised by: a) possibility to use beam-
`forming; b) support for dynamic link adaptation by varying
`the transmit power and potentially modulation and coding, c)
`support for HARQ, and d) support for both dynamic and
`semi-static resource allocation and 2. Random Access Chan-
`
`nel(s) (RACH)is used normally for initial access to a cell, and
`the RACHis characterised by: a) limited data field, and b)
`collision risk.
`
`[0026] The UEs mayreceive system information before the
`UE (e., terminal) accesses a cell in a mobile communication
`system. This system information may contain information
`that is used by the UEsin an Idle state (i.e. when no context
`exists between the UE and the eNB) and in a connectedstate.
`For exemplary purpose only, the main system information
`may be sent on the BCCHlogical channel which is mapped on
`the P-CCPCH (primary CommonControl Physical Channel).
`Also, specific system information blocks may be sent on the
`FACH channel. When the system information is sent on
`FACH, the UE may receive the configuration of the FACH
`either on the BCCHthat is received on P-CCPCH or on a
`
`dedicated channel. Here, the P-CCPCH maybesentusing the
`same scrambling code as the P-CPICH (primary common
`pilot channel) which is the primary scrambling code of the
`
`6
`
`

`

`US 2010/0167746 Al
`
`Jul. 1, 2010
`
`cell. The spreading code that is used by the P-CCPCH may
`have a fixed SF (spreading factor) of 256 and the spreading
`code number may be one. The UE may know about the
`primary scrambling codeeither by information sent from the
`network on system information of neighboring cells that the
`UE hasread(1.e., by messages that the UE has received on the
`DCCHchannel) or by searching for the P-CPICH (whichis
`always sent using the fixed SF 256 and the spreading code
`number0 with a fixed pattern).
`[0027] The system information may include information
`on neighboring cells, configuration of the RACH (Random
`Access Channel) and FACH (ForwardAccess Channel) trans-
`port channels, and the configuration of MICH (MBMSIndi-
`cator Channel) and MCCH (Multicast Control Channel)
`whichare channels that are dedicated channels for the MBMS
`(Multimedia Broadcast/Multicast Service) service. It may be
`camping (in idle mode) whenever the UE changesthe cell, or
`the UE mayneedto verify whetherit has valid system infor-
`mation when the UEhasselected the cell (in CELL_FACH,
`CELL_PCH or URA_PCHstate). The system information
`may be organized in SIBs (system information blocks), a
`MIB (Master information block) and scheduling blocks. The
`MIB maybesent very frequently and may give or provide
`timing information of the scheduling blocks andthe different
`SIBs. For SIBs that are linked to a value tag, the MIB may
`contain information on the last version of a part of the SIBs.
`The SIBs maybelinked to an expiration timerif the SIBs are
`not linked to a value tag. Here, if the time ofthe last reading
`ofthe SIB is bigger than this timervalue, the SIBs linked to an
`expiration timer may become invalid and may need to be
`reread. Also, the SIBs linked to a value tag may be valid ifthey
`have the same valuetag as the one broadcast in the MIB. Each
`block mayincludean area scope ofvalidity (1.e., Cell, Public
`Land Mobile Network (PLMN), equivalent PLMN) which
`signifies on which cells the SIB is valid. For example, a SIB
`with area scope “Cell” maybe valid only for the cell in which
`it has been read. A SIB with area scope “PLMN”maybevalid
`in the whole PLMN.A SIB with the area scope “equivalent
`PLMN”maybe valid in the whole PLMN and equivalent
`PLMN.
`
`[0028] The UEs may read the system information when
`they are in idle mode, CELL_FACHstate, CELL_PCHstate
`or in URA_PCHstate of thecells (1.e., cell that the UE has
`selected, cell that the UE is camping on). The UEs may
`receive information of neighboring cells on the same fre-
`quency, different frequencies and different RAT (Radio
`access technologies). By doing this, the UE may know which
`cells are candidate for cell reselection. Ina CELL_DCHstate,
`the UE may know aboutthe differentradio links other than the
`UE currently use. In this case, it may increase the complexity
`for the UE to read additional channels such as the BCCH
`channels. Therefore the information ofneighboring cells may
`be received in a dedicated message from the RNC, and only
`for somevery specific functions. However, it may be possible
`that UEs read system information sent on the P-CCPCH
`channelor other transport channels in the CELL_DCHstate.
`[0029] The LTE (Long Term Evolution) may be based on
`OFDM (Orthogonal Frequency
`[0030] Division Multiplexing). FIG. 2 shows an exemplary
`transmitter of an OFDM scheme.
`
`Asillustrated in the FIG. 2, an input signal (sym-
`[0031]
`bols) may be modulated using a QAM modulation. The
`stream of modulated signal may be converted in a parallel
`complex bit-stream. Then, the bit-stream may be passed
`
`through a Discrete Fourier conversion block. After the map-
`ping ofthe bits to the relevant frequencies, a vector may be fed
`into the Inverse Fast Fourier transmission block. Here, the
`parallel to serial conversion block may create a complex
`signal. A cyclic prefix may be addedto the symbolin orderto
`handle a multi-path transmission. The outputsignal after each
`IFFT maybe called an OFDM symbol.
`[0032]
`Several OFDM symbols maybe grouped together in
`order to form a sub-frameasillustrated in FIG. 3. The high
`bit-rate stream may be converted in several parallel bit-rate
`streams with lowerdata rate. Thus, each stream uses a smaller
`bandwidth and each stream is more robust for a frequency
`selective fading and multi-paths. Here, as long as the sub-
`carriers are transmitted with the same sub-carrier spacing,it
`maybe possible that the UE receives only parts of the com-
`plete transmission bandwidth as shownin FIG.4. (1.e., shaded
`and un-shaded parts show the sub-carriers that are transmit-
`ted, and the shaded part showsthe sub carriers that are only
`received). Thus, the bandwidth for reception and transmis-
`sion maybe differently used.
`[0033] The LTE system may be designed such that it can
`operate in many different bandwidths (e.g. 20 MHz, 10 MHz,
`5 MHz, 2.5 MHz, and 1.25 MHz). Thus, the UE may not know
`about the bandwidth used by a cell when a UE attemptsto find
`out the existence of a cell. The UE may transmit a reference
`signal, which can be transmitted through a Synchronization
`channel (SCH), in order to allow the UE to find out the
`existence of the cell. Here, the reference signal may betrans-
`mitted on the SCH using a part ofthe total bandwidth in order
`to allow the UEto discover any cell. Therefore, the UE may
`only needto searchfor a limited number of SCH bandwidths.
`[0034] Also, the UE may determinethe existence of a cell
`and may acquire sub-frame synchronization by searching for
`the SCH channel. In order to allow the UE to receive more
`
`information onthe cell characteristics, it may be necessary for
`the UEto receive broadcast information which is carried on
`
`the BCH channel. Such a BCH channel maybe transmitted on
`a limited or part of the total bandwidthjustlike in the case of
`the SCH channel.
`
`In a multi-cell environment, the UE may receive
`[0035]
`different signals (cells) permanently from several base sta-
`tions. In this case, the transmission of the different signals
`maybe not synchronized when the UE decodesthe transmis-
`sion of onecell (e.g. the transmission ofsignal of a cell B may
`create interference with a cell A, and mayincrease the prob-
`ability offalse reception by the cell A). In order to increase the
`probability of correct reception, the cells may transmit the
`same signal in a time aligned mannerwith a coordination of
`their transmission, such that the UE mayjointly decode the
`received signal from both cells as shown in FIG.5. This type
`ofreception mannercan be called soft combining because the
`UE may combinethe received signal of both cells during the
`reception phase. The signals of the different cells are not
`perceived as interference, and thus soft combining may
`increase the quality of the signal received by the UE.
`Although many other different techniques may exist for the
`soft combining, this scheme may require a very strict or tight
`synchronization between the cells. When the OFDM is used
`as a modulation scheme, the time synchronization may need
`to be in the order of a length of a cyclic prefix in order to
`handle a constructive interference.
`
`[0036] Aselective combining maybe usedifa tight level of
`synchronization is not possible. The selective combining
`method can be discriminated to the soft combining, as the
`
`7
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`

`

`US 2010/0167746 Al
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`Jul. 1, 2010
`
`selective combining method allows the UE to receive the
`signals
`sent
`from several base stations independently.
`Although the two cells may not transmit the same signal, the
`UE may knowthatthe twocells transmit the same data. Thus,
`by receiving the transmission of signals of both cells, it may
`be possible to receive data (1.e., RLC PDUs) correctly from
`one cell even though other data has not been correctly
`received by another cell. As such, the selective combining
`method mayincrease the overall quality of the data reception
`[i.e., faster transmission]. Because the selective combining
`may be performed at RLC level, RLC sequence numbers may
`be used in order to re-order the Protocol Data Units (PDUs)
`received from the different cells involved in the selective
`
`combining.
`[0037]
`Duetothe factthat a global downlink capacity [1.e.,
`bandwidth] of a cell is bigger or larger than the reception
`capacity of the UE, the bandwidth of the UE may not be
`utilized or used for a maximum downlink bandwidth.(1.e.,
`only part of total downlink bandwidth is used) Usually, the
`maximum bandwidth for a cell is set to 20 MHz in the LTE
`system, and the UE’s minimum reception bandwidthis set to
`10 MHz. Thus, the UE with 10 MHz receiver may tuneits
`receiver to a leftmost or a rightmost part of the spectrum as
`shownin FIG.6. Therefore, data or signals on the BCH orthe
`SCH maynotbe correctly received if such data or signals are
`transmitted on a center frequency ofthe downlink bandwidth.
`[0038] This disclosure may provide a method or system
`such that the system information is groupedorclassified in
`different types according to the characteristics of the system
`information, and the system information may be sent on
`
`system information may change frequently due to the radio
`communication environment, while other types of system
`information do not change as frequently. As such, the Cell-
`level system information may be further devised in dynamic
`information and semi-static system information depending
`on whetherthe content ofthe information changes frequently
`(dynamic) or not frequently (semi-static).
`
`TABLE1
`
`Different types of system information
`
`Primary System Information
`Secondary System
`Information
`
`Cell-level
`PLMN-level
`
`Semi-static
`Dynamic
`
`[0039] Here, the primary system information may be sent
`on a transport channel with fixed scheduling, such as the
`BCH, whereas the secondary system information may be
`transmitted on a transport channel with flexible scheduling,
`such as DL-SCH. The PLMN-level system information may
`be transmitted with a coordination of neighboring cells such
`that the selective combining or the soft combining can be
`applied. The BCH maybetransmitted in a way that the UEs
`can receive a rightmost, leftmost, or center part of a total
`downlink bandwidth (i.e., 20 MHz spectrum) if the UEs have
`acapability to receive only limited bandwidths(i.e. 10 MHz).
`[0040] The system information may be categorized in
`detail, as shown in Table 2.
`
`TABLE 2
`
`Different types of system information
`
`Primary System Information
`
`Secondary
`System
`Information
`
`Cell-
`level
`
`Semi-
`static
`
`Dynamic
`PLMN-level
`
`
`
`PLMNinformation (e.g. MIB)
`Scheduling information of BCCHblocks,i.e. Secondary
`system information blocks (e.g. R6 MIB or SB)
`Cell selection/re-selection information (e.g. R6 SIB3)
`Semi-static common channel information (e.g. R6
`SIB5/6)
`Measurementcontrol information (e.g. R6 SIB11/12)
`Cell-level Location Service information (e.g. R6 SIB15
`except SIB15.3)
`Information on PLMNidentities of neighbouringcells
`(e.g. SIB18)
`Dynamic common channel information (e.g. R6 SIB7,
`SIB14, SIB17)
`NASsystem information (e.g. R6 SIB1)
`Information on UE timers/counters (e.g. R6 SIB1)
`PLMN-level Location Service information (e.g. R6
`SIB15.3)
`Pre-defined Configurations (e.g. R6 SIB16)
`
`channels with specific functions to allow the optimization of
`the resource usage and the improved reception by the UE.
`Here, the system information may be grouped in primary
`system information and secondary system information as
`shown in Table 1. The primary system information may be
`composed of information that is essential for further recep-
`tion of the secondary system information. The secondary
`system information may be further devised in cell-level sys-
`tem information and PLMN-level
`system information,
`depending on whether a content of the informationis a cell
`specific [i.e., information is only valid in a specific cell] or
`same content for different cells of same PLMN[i.e., infor-
`mation is valid in the entire network]. Also, some types of
`
`[0041] When a UEis located or camped on a cell, the UE
`may read the primary system information of the Table 2
`immediately after a synchronization process by synchroniza-
`tion channel. The primary system Information may have a cell
`specific and semi-static characteristic. The primary system
`information may contain scheduling information of the sec-
`ondary system information blocks. (e.g., R6 MIB or SB)
`Thus, after reading the primary system information, the UE
`can read the secondary system information block on a sched-
`uled time and frequency. The cell-level secondary system
`information of the Table 2 is grouped as the cell-specific.
`Therefore, when the UE movesto a new cell (.e., different
`than current cell), the UE mayreadthe cell-level secondary
`
`8
`
`

`

`US 2010/0167746 Al
`
`Jul. 1, 2010
`
`[0045] Usually, a soft combining may be considered better
`system information in the new cell regardless ofreading ofthe
`than a selective combining in terms of performance. There-
`cell-level secondary system information of a previouscell.
`fore, the soft combining may be applied to the PLMN-level
`[0042] The dynamic cell-level secondary system informa-
`system information like SIB1 and SIB 16inaLTEsystem. As
`tion ofthe Table 2 may includefast changing parameters such
`such,a first layer (L1) may provide a specific commonpilot
`as interference. It may be used for a commonchannelsuch as
`and long cyclic prefix for the SIB1 and SIB16. In addition, a
`Random Access Channel (RACH). Here, except for the
`synchronoustime and/or frequency transmission of the spe-
`dynamic cell-level secondary system Information, all of the
`cific system information between cells may needto be pro-
`cell-level secondary system informationofthe Table 2 may be
`vided. Alternatively, the selective combining maybe applied
`considered as semi-static. (i.e., content is not frequently
`to the PLMN-level system information like SIB1 and SIB16
`changed) The PLMN-level secondary system information of
`in the LTE system.Here,thefirst layer (L1) may not need to
`Table 2 may be not cell-specific, but common to multiple cells
`consider the specific common pilots, the length of cyclic
`in PLMNarea. Thus, if the UE, which has read the PLMN-
`prefix and synchronoustransmissions. However, a UE should
`level secondary system information in a previous cell moves
`decode multiple cells to selectively combine BCCHchannels
`to anew cell and the PLMN-level secondary system informa-
`of multiple cells. Moreover, the UE should apply duplication
`tion has not been modified, the UE may not need to read the
`avoidance function in a second layer (L2). For this duplica-
`same PLMN-level secondary system information in a new
`tion avoidance function, an aGW may need to provide
`sequence numbers of the PLMN-level system information.
`cell. Here, the PLMN-level secondary system information
`usually has semi-static characteristic.
`[0046] The special case of 20 MHz system bandwidth
`where a UEis receiving onepart of the carriers is shown in
`[0043]
`For the system information in a LTE system, a MIB
`FIG.7. As illustrated in FIG. 7, the UE, whichis allocated to
`mayuseafixed resource because the UE maynot presumably
`a right half of a bandwidth, may not able to recetve a BCH
`acquire any control information before receiving the MIB in
`correctly in the case that the BCH is coded andpositioned on
`a cell. However, eNB can schedule SIBs (i.e., SIBs on SCH)
`a center frequency. Thus, in order to allow that the UE can
`within a specific Transmission TimeIntervals (TTI) indicated
`receive the BCH in all cases, the BCH should be transmitted
`by the MIB. Ifacertain SIB is scheduled within a certain TTI,
`in a different manner. Here, an alternative 1 or an alternative
`control information of the TTI may indicate existence of a
`2 may be proposed.In thealternative 1, the BCH blocks may
`SIB in the TTI and mayschedule a time or fr