(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0167746 A1
` Lee et al. (43) Pub. Date: Jul. 1, 2010
`
`
`
`US 20100167746A1
`
`(54) METHOD OF TRANSMITTING/RECEIVING
`LTE SYSTEM INFORMATION IN A
`WIRELESS COMMUNICATION SYSTEM
`
`(86) PCT No.:
`
`PCT/KR07/01335
`
`§ 371 (0)0),
`(2), (4) Date:
`
`Sep. 19, 2008
`
`(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
`
`Related U'S' Application Data
`(60) Provisional application No. 60/784,680, filed on Mar.
`21a 2006.
`
`.
`.
`.
`.
`Publication ClaSSIficatlon
`
`(51)
`
`Int. Cl.
`H04W 72/00
`(2009.01)
`H04K [/10
`(2006.01)
`.
`(52) US. Cl. ......................................... 455/450, 375/260
`(57)
`ABSTRACT
`In a wireless mobile communications system, the system
`information is grouped or classified 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).
`
`eNB
`
`inter Cell RRM
`
`Connection
`Mobility Cont.
`
`i
`
`RB Control
`
`__.____.__.—.‘
`Radio
`Admission
`Control
`
`eNB
`Measurement
`Configuration&
`Provision
`
`Dynamic
`Resource
`Allocation
`S h d |
`( C e uer)
`
`
`RRC
`
`
`RLC
`
`
`g
`i
`
`5
`E
`E
`E
`ISI
`
`é
`
`E
`
`
`
`
`
`aGW Control Plane
`
`
`
`SAE Bearer
`Control
`
`1
`
`MM Entity
`
`aGW User Piane
`
`
`
`
`
`
`
`
`
`MW
`
`I i
`
`51
`
`
`
`:
`lII
`—————2— User Plane &
`
`1
`
`SAMSUNG 1004
`
`
`MAC
`5
`PDCP
`
`PHY
`
`
`
`.
`
`SAMSUNG 1004
`
`1
`
`

`

`Patent Application Publication
`
`Jul. 1, 2010 Sheet 1 0f 3
`
`US 2010/0167746 A1
`
`
`[Fig. 1]
`eNB
`
`i
`
`Inter Cell RRM
`
`Connection
`Mobility Cont
`
`RB Control
`
`Radio
`Admission
`Control
`
`
`Dynamic
`Resource
`Allocation
`
`(Scheduler)
`
`RRC
`
`RLC
`
`
`
`eNB
`Measurement
`Configuration&
`aGW Control Plane
`Provision
`
`
`SAE Bearer
`
`Control
`
`MAC
`PDCP
`
`U) A
`
`User Plane
`PHY
`W,
`,
`.
`.J
`
`
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`
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`
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`MM Entity
`
`aGW User Plane
`
`m_/m\\
`1
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`inferno:
`
`‘
`‘
`\W
`
`
`
`ununu-uu-o-u-u-n-uuuumun-u-uuunun—onu‘cun
`
`
`
`
`
`
`
`
`
`
`
`
`[Fig. 2]
`
`[Fig. 3]
`
`
`
`‘
`Modulation
`
`“’ DFT ‘
`_
`—> for 11"
`S/P -> UL f" Mapping
`" only 3”,
`
`i
`"
`3'FFT
`
`
`
`PIS
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`I
`
`Cyclic
`prefix
`
`1 sub —frame
`
`Sub .
`
`frame with short CP
`
`Sub ~
`
`frame with long CP
`
`
`
`
`
`
`2
`
`

`

`Patent Application Publication
`
`Jul. 1, 2010 Sheet 2 of 3
`
`US 2010/0167746 A1
`
`[Fig. 4]
`
`Subcarriers
`
`WWW
`
`
`Frequency
`
`[Fig.5]
`
`Cell A
`
`(c
`
`J)
`
`Cell 8
`
`(c
`
`:1)
`
`
`
`LJEA
`
`[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 A1
`
`5‘ alternative move BCH to the upper 10 MHZ or
`to the lower 10 MHZ part
`
`mum
`
`m‘
`
`‘L
`
`
`
`
`
`[Fig. 7]
`
`UE is receiving one part of the
`10 MHZ of the 20 MHZ spectrum
`
`[Fig. 8]
`
`\ 2“d alternative splitthe ECU in
`
`two separately decodable blocks
`such the UE can decode the block.
`The impact is that the block is smaller,
`hence the efficiency is smaller
`
`
`
`SCH
`
`
`
`
`
`Secondary BCH
`
`
`
`/::j
`\:
`
`4
`
`

`

`US 2010/0167746 A1
`
`Jul. 1,2010
`
`METHOD OF TRANSMITTING/RECEIVING
`LTE SYSTEM INFORMATION IN A
`WIRELESS COMMUNICATION SYSTEM
`
`[0001] This application claims priority to US. Patent Pro-
`visional Application No. 60/784,680, filed on Mar. 21, 2006,
`which is incorporated herein by reference.
`
`DISCLOSURE OF INVENTION
`
`Technical Solution
`
`[0002] This disclosure relates to a wireless communication
`system, more particularly, to a method oftransmitting/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 one static
`channel for the transmission of system information would not
`allow to optimize the transmission or reception of the system
`information.
`
`[0004] This disclosure has been developed in order to solve
`the above described problems of the related art. As a result,
`this disclosure provides a method of transmitting and/or
`receiving the system information on an OFDM air interface 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 problems due to limitations and disadvantages of the
`related art.
`
`To implement at 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 grouped or classified in
`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-
`tions that allow the optimization ofthe resource usage and the
`reception by the User Equipment (UE), wherein the different
`types of channels may be a statically scheduled channel and/
`or a flexibly scheduled channel.
`[0007] Additional features of this disclosure will be set
`forth in part in the description which follows and in part will
`become apparent to those having ordinary skill in the art upon
`examination ofthe following or may be learned from practice
`ofthis disclosure. The objectives and other advantages ofthis
`disclosure may be realized and attained by the structure par-
`ticularly pointed out in the written description and claims
`hereof as well as the appended drawings.
`[0008]
`FIG. 1 is an exemplary diagram illustrating protocol
`architecture of the E-UTRAN.
`
`FIG. 2 shows an exemplary structure of an OFDM
`[0009]
`transmission.
`
`FIG. 3 shows an exemplary structure of an OFDM
`[0010]
`sub-frame structure.
`
`FIG. 4 shows an exemplary diagram illustrating
`[0011]
`sub-carriers 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 UE in 20 MHz spectrum 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 BCH in 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 3GPP specifications, 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 network structure of
`an E-UMTS (Evolved-Universal Mobile Telecommunica-
`tions System) to which technical features of this disclosure
`may be applied. Recently, an initiative has been started in the
`scope of the 3GPP (3rd Generation Partnership Project).
`project to standardize a new air 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 (Frequency division
`multiplexing)), and the 3rd generation air interface (as known
`under the name UMTS and based 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-UMTS is a system evolving from the conventional UMTS
`and its basic standardization is currently handled by the
`3GPP.
`
`[0020] Referring to FIG. 1, an E-UMTS network includes a
`user equipment (hereinafter abbreviated ‘UE’), a base station
`(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-UMTS net-
`work. The eNB and the aGW are connected via an interface
`
`called 81 . The aGW may be classified into a part for handling
`user traffic and a part for handling control traffic. A first aGW
`for processing new user trafiic may communicate with a
`second AGW for processing control traffic via a new inter-
`face. A first interface for transmitting user traffic or a second
`interface for transmitting control
`traffic may be located
`between several eNBs. Here, the eNB may include at least
`one cell.
`
`[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
`
`

`

`US 2010/0167746 A1
`
`Jul. 1,2010
`
`radio bearer control, a radio admission control (RAC), and a
`connection mobility control in LTE_ACTIVE state.
`[0022] The functions located in the eNB will be briefly
`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. The radio
`bearer (RB) is a service provided by the second layer (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 resources are available and the admission would not
`endanger the 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 and to 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
`may perform segmentation, concatenation in sequence deliv-
`ery, repetition, error recovery and other functions in order to
`exchange Service Data Units (SDUs) between the eNB an the
`UE entity. 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 MAC layer 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]
`In the E-UTRAN, the AGW may perform 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 and integrity
`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 UTRAN to 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 may satisfy 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
`(TMSI) and so on. The Packed Data Convergence Protocol
`(PDCP) layer may be located above the RLC layer. The PDCP
`layer may be used to transmit network protocol data, such as
`the IPv4 or IPv6, efiiciently 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
`PDCP layer may provide ciphering and integrity protection
`for the transmitted data.
`
`[0025] Transport channels may be introduced in 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 MAC layer 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) requirement to 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 dynamic link 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 MBMS transmission
`(FFS) 3. Paging Channel (PCH) is characterised by: a) sup-
`port for UE discontinuous reception (DRX) to enable UE
`power saving (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) mapped to physical resources which
`can be used dynamically also for traffic or other control
`channels, and 4. Multicast Channel (MCH) is characterised
`by: a) requirement to be broadcast in the entire coverage area
`of the cell, b) support for combining of MBMS transmission
`on multiple cells (the exact combining scheme is FPS), and c)
`support for semi-static resource allocation (e.g., with a time
`frame of a long cyclic prefix). Also, types of uplink transport
`channels can be described as follows; l.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 RACH is characterised by: a) limited data field, and b)
`collision risk.
`
`[0026] The UEs may receive system information before the
`UE (i.e., terminal) accesses a cell in a mobile communication
`system. This system information may contain information
`that is used by the UEs in an Idle state (i.e. when no context
`exists between the UE and the eNB) and in a connected state.
`For exemplary purpose only, the main system information
`may be sent on the BCCH logical channel which is mapped on
`the P-CCPCH (primary Common Control 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 BCCH that is received on P-CCPCH or on a
`
`dedicated channel. Here, the P-CCPCH may be sent using the
`same scrambling code as the P-CPICH (primary common
`pilot channel) which is the primary scrambling code of the
`
`6
`
`

`

`US 2010/0167746 A1
`
`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 code either by information sent from the
`network on system information of neighboring cells that the
`UE has read (i.e., by messages that the UE has received on the
`DCCH channel) or by searching for the P-CPICH (which is
`always sent using the fixed SF 256 and the spreading code
`number 0 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 (MBMS Indi-
`cator Channel) and MCCH (Multicast Control Channel)
`which are channels that are dedicated channels for the MBMS
`
`(Multimedia Broadcast/Multicast Service) service. It may be
`camping (in idle mode) whenever the UE changes the cell, or
`the UE may need to verify whether it has valid system infor-
`mation when the UE has selected the cell (in CELL_FACH,
`CELL_PCH or URA_PCH state). The system information
`may be organized in SIBs (system information blocks), a
`MIB (Master information block) and scheduling blocks. The
`MIB may be sent very frequently and may give or provide
`timing information of the scheduling blocks and the 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 may be linked to an expiration timer if the SIBs are
`not linked to a value tag. Here, if the time of the last reading
`ofthe SIB is bigger than this timer value, 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 value tag as the one broadcast in the MIB. Each
`block may include an area scope of validity (i.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” may be valid only for the cell in which
`it has been read. A SIB with area scope “PLMN” may be valid
`in the whole PLMN. A SIB with the area scope “equivalent
`PLMN” may be valid in the whole PLMN and equivalent
`PLMN.
`
`[0028] The UEs may read the system information when
`they are in idle mode, CELL_FACH state, CELL_PCH state
`or in URA_PCH state of the cells (i.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. In a CELL_DCH state,
`the UE may know about the different radio 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 some very specific functions. However, it may be possible
`that UEs read system information sent on the P-CCPCH
`channel or other transport channels in the CELL_DCH state.
`[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.
`
`[0031] As illustrated in the FIG. 2, an input signal (sym-
`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 added to the symbol in order to
`handle a multi-path transmission. The output signal after each
`IFFT may be called an OFDM symbol.
`[0032]
`Several OFDM symbols may be grouped together in
`order to form a sub-frame as illustrated in FIG. 3. The high
`bit-rate stream may be converted in several parallel bit-rate
`streams with lower data 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
`may be possible that the UE receives only parts of the com-
`plete transmission bandwidth as shown in FIG. 4. (i .e., shaded
`and un-shaded parts show the sub-carriers that are transmit-
`ted, and the shaded part shows the sub carriers that are only
`received). Thus, the bandwidth for reception and transmis-
`sion may be 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 attempts to 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 be trans-
`mitted on the SCH using a part ofthe total bandwidth in order
`to allow the UE to discover any cell. Therefore, the UE may
`only need to search for a limited number of SCH bandwidths.
`[0034] Also, the UE may determine the 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 on the cell characteristics, it may be necessary for
`the UE to receive broadcast information which is carried on
`
`the BCH channel. Such a BCH channel may be transmitted on
`a limited or part of the total bandwidth just like 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
`may be not synchronized when the UE decodes the transmis-
`sion of one cell (e. g. the transmission of signal of a cell B may
`create interference with a cell A, and may increase 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 manner with a coordination of
`their transmission, such that the UE may jointly decode the
`received signal from both cells as shown in FIG. 5. This type
`ofreception manner can be called soft combining because the
`UE may combine the 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] A selective combining may be used if a tight level of
`synchronization is not possible. The selective combining
`method can be discriminated to the soft combining, as the
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`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 know that the two cells transmit the same data. Thus,
`by receiving the transmission of signals of both cells, it may
`be possible to receive data (i.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 may increase 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] Due to the fact that a global downlink capacity [i.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. (i.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 bandwidth is set to
`10 MHZ. Thus, the UE with 10 MHZ receiver may tune its
`receiver to a leftmost or a rightmost part of the spectrum as
`shown in FIG. 6. Therefore, data or signals on the BCH or the
`SCH may not be 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 grouped or classified 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 whether the content ofthe information changes frequently
`(dynamic) or not frequently (semi-static).
`
`TABLE 1
`
`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 may be transmitted 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
`a capability 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
`
`PLMN information (e.g. MIB)
`Sc ieduling information ofBCCH blocks, 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
`SI 35/6)
`Measurement control information (e.g. R6 SIB11/12)
`Cell-level Location Service information (e.g. R6 SIB15
`except SIB15.3)
`In ormation on PLMN identities of neighbouring cells
`(e.g. SIB 1 8)
`Dynamic common channel information (e.g. R6 SIB7,
`S1314, SIB17)
`NAS system information (e. g. R6 SIBl)
`In ormation on UE timers/counters (e.g. R6 SIBl)
`PLMN-level Location Service information (e. g. R6
`SI 3 15 .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 information is 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 UE is 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 moves to a new cell (i.e., different
`than current cell), the UE may read the cell-level secondary
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`system information in the new cell regardless ofreading ofthe
`cell-level secondary system information of a previous cell.
`[0042] The dynamic cell-level secondary system informa-
`tion ofthe Table 2 may include fast changing parameters such
`as interference. It may be used for a common channel such as
`Random Access Channel (RACH). Here, except for the
`dynamic cell-level secondary system Information, all of the
`cell-level secondary system information ofthe Table 2 may be
`considered as semi-static. (i.e., content is not frequently
`changed) The PLMN-level secondary system information of
`Table 2 may be not cell-specific, but common to multiple cells
`in PLMN area. Thus, if the UE, which has read the PLMN-
`level secondary system information in a previous cell moves
`to a new cell and the PLMN-level secondary system informa-
`tion has not been modified, the UE may not need to read the
`same PLMN-level secondary system information in a new
`cell. Here, the PLMN-level secondary system information
`usually has semi-static characteristic.
`[0043]
`For the system information in a LTE system, a MIB
`may use a fixed resource because the UE may not presumably
`acquire any control information before receiving the MIB in
`a cell. However, eNB can schedule SIBs (i.e., SIBs on SCH)
`within a specific Transmission Time Intervals (TTI) indicated
`by the MIB. If a certain SIB is scheduled within a certain TTI,
`control information of the TTI may indicate existence of a
`SIB in the TTI and may schedule a time or frequency of the
`SIB. As such, the eNB may have more flexible size ofthe SIB
`within a range ofminimum UE capability. Also, the eNB may
`have more flexibility of SCH scheduling. In details, the UE
`may receive the MIB at the fixed downlink (DL) resource
`(e. g. time/code/frequency). If the MIB includes long-term
`scheduling information of SIB transmissions and the UE has
`a specific SIB, the UE may receive a DL control channel for
`one or more TTIs indicated by the long-term scheduling
`information of the SIB in order to acquire a short-term sched-
`uling of the SIB. And then, if the UE find that the short-term
`scheduling information at the TTI on the DL control channel
`indicates the existence of the SIB in this TTI and the UE
`
`successfully receives the short-term scheduling information
`of the SIB, the UE may receive the SIB at the DL resource on
`a DL broadcast channel (e.g. time and frequency of the DL
`broadcast channel) indicated by the short-term scheduling of
`the SIB. Afterwards, UE may operate based on the received
`SIB.
`
`[0044] The BCH channel may have a globally fixed con-
`figuration for UEs to decode without any control information.
`Thus, the primary system information may be broadcast on
`the BCH. Here, the secondary system information may be
`broadcasted on DL SC