WO2009014356A1 - Procédé de génération de trame descendante et procédé de recherche de cellule - Google Patents

Procédé de génération de trame descendante et procédé de recherche de cellule Download PDF

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Publication number
WO2009014356A1
WO2009014356A1 PCT/KR2008/004224 KR2008004224W WO2009014356A1 WO 2009014356 A1 WO2009014356 A1 WO 2009014356A1 KR 2008004224 W KR2008004224 W KR 2008004224W WO 2009014356 A1 WO2009014356 A1 WO 2009014356A1
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WIPO (PCT)
Prior art keywords
sequence
short
scrambling
synchronization signal
short sequence
Prior art date
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PCT/KR2008/004224
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English (en)
Inventor
Kap Seok Chang
Il Gyu Kim
Hyeong Geun Park
Young Jo Ko
Hyo Seok Yi
Chan Bok Jeong
Young Hoon Kim
Seung Chan Bang
Original Assignee
Electronics And Telecommunications Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR20080044413A external-priority patent/KR20090009696A/ko
Application filed by Electronics And Telecommunications Research Institute filed Critical Electronics And Telecommunications Research Institute
Priority to EP08778879A priority Critical patent/EP2137872B1/fr
Priority to BRPI0809496-9A priority patent/BRPI0809496A2/pt
Priority to JP2010516932A priority patent/JP5140728B2/ja
Priority to AU2008279973A priority patent/AU2008279973B2/en
Priority to CN2008800015550A priority patent/CN101578810B/zh
Priority to DE602008003424T priority patent/DE602008003424D1/de
Priority to AT08778879T priority patent/ATE488067T1/de
Publication of WO2009014356A1 publication Critical patent/WO2009014356A1/fr
Priority to US12/488,286 priority patent/US8331564B2/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2643—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using time-division multiple access [TDMA]
    • H04B7/2656—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using time-division multiple access [TDMA] for structure of frame, burst
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0069—Cell search, i.e. determining cell identity [cell-ID]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/04—Speed or phase control by synchronisation signals
    • H04L7/041—Speed or phase control by synchronisation signals using special codes as synchronising signal
    • H04L7/043—Pseudo-noise [PN] codes variable during transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7073—Synchronisation aspects
    • H04B1/70735—Code identification
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2662—Symbol synchronisation

Definitions

  • the present invention relates to a method of generating a downlink frame and a method of searching cells. More particularly, the present invention relates to a method of generating a downlink frame and a method of searching cells by using the downlink frame in an orthogonal frequency division multiplexing (OFDM)-based cellular system.
  • OFDM orthogonal frequency division multiplexing
  • a sequence hopping method is applied to a pilot channel so as to acquire cell synchronization and unique cell identification information.
  • a mobile station easily performs a cell search without a separating synchronization channel by introducing a sequence hopping technology to the pilot channel.
  • a number of channels that are capable of being distinguished by a frequency domain in a symbol duration of one time domain is greater than that of those that are capable of being distinguished by a spread of CDMA in the symbol duration of one time domain. Accordingly, when only the time domain is used, resources may be wasted in terms of capacity. For this reason, it is inefficient to directly apply the sequence hopping method to the time domain of the pilot channel in the OFDM-based system. Therefore, it is preferable to search the cell by efficiently using received signals in both time domain and frequency domain.
  • An example of an existing technology for searching a cell in the OFDM system includes a method that allocates synchronization information and cell information by dividing one frame into four time blocks.
  • two frame structures have been proposed.
  • synchronization identification information, cell group identification information, and cell unique identification information are allocated to four time blocks, respectively.
  • the synchronization identification information and the cell unique identification information are allocated to a first time block and a third time block, and the synchronization identification information and the cell group identification information are allocated to a second time block and a fourth time block.
  • the mobile station since the symbol synchronization is acquired in only the first time block, it is impossible for the mobile station to conduct rapid synchronization acquisition within a prescribed 5ms during power-on or handover between heterogeneous networks. In addition, it is difficult to acquire diversity gain by accumulating synchronization identification information so as to conduct rapid synchronization acquisition.
  • the unique cell identification information or the cell group identification information is correlated along with the synchronization acquisition. Therefore, a cell searching process is complex and a rapid cell search is difficult.
  • a method of acquiring the synchronization and searching the cell by using a separate preamble has been proposed. However, this method cannot be applied to a system in which the preamble does not exist.
  • the preamble is disposed in front of the frame. Accordingly, in a case in which the mobile station would like to acquire the synchronization at a time location that is not the start of the frame, there is a problem in that it must wait for the next frame. Particularly, the mobile station should acquire initial symbol synchronization within 5 msec during the handover among a GSM mode, a WCDMA mode, and a 3GPP LTE mode, but may acquire the synchronization by a frame unit. For this reason, in some cases, the mobile station cannot acquire the initial symbol synchronization within 5 msec.
  • the present invention has been made in an effort to provide a method of generating a downlink frame that is capable of averaging interference between sectors and a method of efficiently searching cells by receiving the downlink frame.
  • An exemplary embodiment of the present invention provides a method of generating a downlink frame, including : generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by a short sequence group-a wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned; scrambling the first short sequence with the first scrambling sequence and scrambling the second short sequence with the second scrambling sequence and the third scrambling sequence; and mapping the secondary synchronization signal that includes the scrambled first short sequence and the scrambled second short sequence to a frequency domain.
  • Another exemplary embodiment of the present invention provides a method of generating a downlink frame, including : generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by a short sequence group-a wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned and a fourth scrambling sequence determined by a short sequence group to which the second short sequence is assigned; scrambling the first short sequence with the first scrambling sequence and scrambling the second short sequence with the second scrambling sequence and the third scrambling sequence; scrambling the second short sequence with the first scrambling sequence and scrambling the first short sequence with the second scrambling sequence and the fourth scrambling sequence; and mapping the secondary synchronization signal that includes the first short sequence scrambled with the first scrambling sequence, the second
  • Yet another embodiment of the present invention provides an apparatus for generating a downlink frame including: a sequence generating unit that generates a first short sequence and a second short sequence indicating cell group information, a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal, and a third scrambling sequence determined by a short sequence group-the wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned; and a synchronization signal generating unit that scrambles the first short sequence with the first scrambling sequence and scrambles the second short sequence with the second scrambling sequence and the third scrambling sequence, and then generates a secondary synchronization signal including the scrambled first short sequence and the scrambled second short sequence respectively.
  • Yet another embodiment of the present invention provides a method of searching a cell, including: receiving a downlink frame including a primary synchronization signal and a secondary synchronization signal; and estimating cell information by using the primary synchronization signal and the secondary synchronization signal.
  • a first short sequence scrambled with a first scrambling sequence and a second short sequence scrambled with a second scrambling sequence and a third scrambling sequence are alternately disposed on a plurality of sub-carriers, and the first short sequence and the second short sequence indicate cell group information
  • the first scrambling sequence and the second scrambling sequence are determined by the primary synchronization signal
  • the third scrambling sequence is determined by a short sequence group-a wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned;
  • Still another embodiment of the present invention provides an apparatus for searching a cell, including: a receiving unit that receives
  • a first short sequence scrambled with a first scrambling sequence and a second short sequence scrambled with a second scrambling sequence and a third scrambling sequence are alternately disposed on a plurality of sub-carriers, and the first short sequence and the second short sequence indicate cell group information, the first scrambling sequence and the second scrambling sequence are determined by the primary synchronization signal, and the third scrambling sequence is determined by a short sequence group-the wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned;
  • Still another embodiment of the present invention provides a recording medium that records a program for executing the method of generating the downlink frame.
  • the recording medium records a program including: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by a short sequence group-the wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned; scrambling the first short sequence with the first scrambling sequence and scrambling the second short sequence with the second scrambling sequence and the third scrambling sequence; and mapping the secondary synchronization signal that includes the scrambled first short sequence and the scrambled second short sequence to a frequency domain.
  • Still another embodiment of the present invention provides a recording medium that records a program for executing the method of generating the downlink frame.
  • the recording medium records a program including: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by a short sequence group-the wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned and a fourth scrambling sequence determined by a short sequence group to which the second short sequence is assigned; scrambling the first short sequence with the first scrambling sequence and scrambling the second short sequence with the second scrambling sequence and the third scrambling sequence; scrambling the second short sequence with the first scrambling sequence and scrambling the first short sequence with the second scrambling sequence and the fourth scrambling sequence; and mapping the secondary synchronization signal that includes the
  • FIG. 1 is a diagram illustrating a downlink frame in an OFDM system according to an exemplary embodiment of the present invention.
  • FIG. 2 is a diagram illustrating a configuration of a secondary synchronization channel when two sequences are mapped to a frequency domain in a localization form.
  • FIG. 3 is a diagram illustrating a configuration of a secondary synchronization channel when two sequences are mapped to a frequency domain in a distribution form.
  • FIG. 4 is a block diagram of an apparatus for generating a downlink frame according to the exemplary embodiment of the present invention.
  • FIG. 5 is a flowchart illustrating a method of generating a downlink frame according to the exemplary embodiment of the present invention.
  • FIG. 6 is a diagram illustrating a first method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention.
  • FIG. 7 is a diagram illustrating a second method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention.
  • FIG. 8 is a diagram illustrating a third method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention.
  • FIG. 9 is a block diagram of an apparatus for searching cells according to an exemplary embodiment of the present invention.
  • FIG. 10 is a flowchart illustrating a method of searching a cell according to a first exemplary embodiment of the present invention.
  • FIG. 11 is a flowchart illustrating a method of searching a cell according to a second exemplary embodiment of the present invention. [Best Mode]
  • the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
  • the term “unit” described in the specification means a unit for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.
  • FIGS. 1 to 3 a downlink frame of an OFDM system and a configuration of a synchronization channel according to an exemplary embodiment of the present invention will be described.
  • FIG. 1 is a diagram illustrating a downlink frame of an OFDM system according to an exemplary embodiment of the present invention.
  • a horizontal axis represents a time axis and a vertical axis represents a frequency axis or sub-carrier axis.
  • a downlink frame 1 10 has a time duration of 10msec and includes ten sub-frames 120.
  • Each sub-frame 120 has a time duration of 1 msec and includes two slots 130.
  • Each slot 130 includes six or seven OFDM symbols.
  • the length of a cyclic prefix in a case in which one slot includes six symbols is greater than that of a cyclic prefix in a case in which one slot includes seven symbols.
  • the downlink frame 1 10 according to the exemplary embodiment of the present invention includes two synchronization durations 140 in total, including synchronization durations 140 in slot No. 0 and slot No. 10, respectively. However, it is not necessarily limited thereto.
  • the downlink frame 110 may include a synchronization duration in any slot, and may include one synchronization duration or three or more synchronization durations. Since the length of the cyclic prefix may be different in each slot, it is preferable that the synchronization duration is located at an end of the slot. Each slot includes a pilot duration.
  • the synchronization duration includes a primary synchronization channel and a secondary synchronization channel, and the primary synchronization channel and the secondary synchronization channel are disposed so as to be adjacent to each other in view of time. As shown in FIG. 1 , the primary synchronization channel is located at the end of the slot, and the secondary synchronization channel is located right ahead of the primary synchronization channel.
  • the primary synchronization channel includes a primary synchronization signal having information for identifying symbol synchronization and frequency synchronization, and some information for cell identification(ID).
  • the secondary synchronization channel includes a secondary synchronization signal having remaining information for the cell ID, and information for identifying frame synchronization.
  • a mobile station identifies the cell ID of cell by combining the cell ID information of the primary synchronization channel and the cell ID information of the secondary synchronization channel.
  • the information on all of the 510 cell IDs can be represented.
  • Another method is that the 510 cell IDs are divided into 170 groups by using 170 secondary synchronization signals that are allocated to the secondary synchronization channel, and information on cell IDs in each cell group can be represented by three primary synchronization signals that are allocated to the primary synchronization channel.
  • the secondary synchronization channel includes the information for identifying the frame synchronization as well as information for the cell ID, two secondary synchronization channels included in one frame are different from each other.
  • FIG. 2 is a diagram illustrating a configuration of a secondary synchronization channel when two short sequences are mapped to a frequency domain in a localization form
  • FIG. 3 is a diagram illustrating a configuration of a secondary synchronization channel when two short sequences are mapped to a frequency domain in a distribution form.
  • a secondary synchronization signal which is inserted into a secondary synchronization channel, according to an exemplary embodiment of the present invention is formed by combining two short sequences. Cell group information and frame synchronization information are mapped to the two short sequences.
  • a first short sequence may be locally allocated to sub-carriers, and then the second short sequence may be locally allocated to remaining sub-carriers.
  • the short sequence length corresponds to half of the number of sub-carriers allocated to the secondary synchronization channel. That is, the number of short sequence elements that can be generated is up to half of the number of sub-carriers allocated to the secondary synchronization channel. For instance, when the number of sub-carriers allocated to the secondary synchronization channel is 62, the short sequence length corresponds to 31 and the number of short sequence elements that can be generated is up to 31.
  • FIG. 4 is a block diagram of the apparatus for generating the downlink frame according to the exemplary embodiment of the present invention. As shown in FIG.
  • the apparatus for generating the downlink frame includes a sequence generating unit 410, a synchronization signal generating unit 420, a frequency mapping unit 430, and an OFDM transmitting unit 440.
  • the sequence generating unit 410 generates a sequence for acquiring time and frequency synchronization, a cell identification sequence, a plurality of short sequences, and a scrambling sequence for reducing adjacent cell interference, respectively, and transmits them to the synchronization signal generating unit 420.
  • the synchronization signal generating unit 420 generates a primary synchronization signal, a secondary synchronization signal, and a pilot pattern by using sequences received from the sequence generating unit 410.
  • the synchronization signal generating unit 420 generates the primary synchronization signal by using the sequence for acquiring time and frequency synchronization and the cell identification sequence. In addition, the synchronization signal generating unit 420 generates the secondary synchronization signal by using the plurality of short sequences and the scrambling sequences for reducing adjacent cell interference.
  • the synchronization signal generating unit 420 generates the pilot pattern of downlink signals by allocating a unique scrambling sequence allocated to each cell for encoding a common pilot symbol and data symbol of a cellular system to the pilot channel.
  • the frequency mapping unit 430 generates the downlink frame by mapping the primary synchronization signal, the secondary synchronization signal, and the pilot pattern that are generated from the synchronization signal generating unit 420 and frame control information and transmission traffic data that are transmitted from external sources to the time and frequency domains.
  • the OFDM transmitting unit 440 receives the downlink frame from the frequency mapping unit 430 and transmits the downlink frame through given transmission antenna.
  • FIG. 5 is a flowchart illustrating the method of generating the downlink frame according to the exemplary embodiment of the present invention.
  • the sequence generating unit 410 generates a plurality of short sequences and a plurality of scrambling sequences for reducing interference of a plurality of adjacent cells and transmits them to the synchronization signal generating unit 420 (S510).
  • the synchronization signal generating unit 420 generates a secondary synchronization signal by using the short sequences and the scrambling sequences for reducing interference of the plurality of adjacent cells received from the sequence generating unit 410 (S520).
  • S520 sequence generating unit 410
  • one frame includes two secondary synchronization channels. However, it is not limited thereto.
  • FIG. 6 is a diagram illustrating the first method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention
  • FIG. 7 is a diagram illustrating the second method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention
  • FIG. 8 is a diagram illustrating the third method of generating a secondary synchronization signal according to the exemplary embodiment of the present invention.
  • a short sequence (wn) is a binary sequence (or binary code) representing cell group information. That is, the short sequence (wn) is the binary sequence allocated to a cell group number and frame synchronization.
  • the length of the short sequence corresponds to half of the number of sub-carriers allocated to the secondary synchronization channel.
  • the number of sub-carriers allocated to the secondary synchronization channel is 62.
  • the short sequence length according to the exemplary embodiment of the present invention is 31.
  • the first short sequence w ⁇ is allocated to even-numbered sub-carriers of the first secondary synchronization channel and is defined as given in Equation 1.
  • k denotes an index of the even-numbered sub-carriers used for a secondary synchronization channel.
  • the second short sequence w1 is allocated to odd-numbered sub-carriers of the first secondary synchronization channel and is defined as given in Equation 2.
  • m denotes an index of the odd-numbered sub-carriers used for the secondary synchronization channel.
  • the third short sequence w2 is allocated to even-numbered sub-carriers of the second secondary synchronization channel and is defined as given in Equation 3.
  • the fourth short sequence w3 is allocated to odd-numbered sub-carriers of the second secondary synchronization channel and is defined as given in Equation 4.
  • the short sequences w ⁇ , w1 , w2, and w3 may be different sequences.
  • the first short sequence is allocated to every even-numbered sub-carrier of the first secondary synchronization channel and the second short sequence is allocated to every odd-numbered sub-carrier of the first secondary synchronization channel.
  • the third short sequence is allocated to every even-numbered sub-carrier of the second secondary synchronization channel and the fourth short sequence is allocated to every odd-numbered sub-carrier of the second secondary synchronization channel.
  • the secondary synchronization signal is formed by a combination of two short sequences having the length of 31. Accordingly, the number of secondary synchronization signals is 961 which is a sufficiently large value in comparison with the number 170 or 340.
  • a first sequence determined by Equation 5 is allocated to every even-numbered sub-carrier of the first secondary synchronization channel(slot 0), and a second sequence determined by Equation 6 is allocated to every odd-numbered sub-carrier of the first secondary synchronization channel(slot 0).
  • a third sequence determined by Equation 7 is allocated to every even-numbered sub-carrier of the second secondary synchronization channel(slot 10)
  • a fourth sequence determined by Equation 8 is allocated to every odd-numbered sub-carrier of the second secondary synchronization channel(slot 10).
  • a scrambling sequence P j, o,i scrambling the first short sequence w ⁇ is defined by 1 , 2) is the number of the cell identification sequence allocated to the primary synchronization channel. Accordingly, the scrambling sequence Pj 1 O 11 is determined by the primary synchronization signal.
  • the scrambling sequence P j ,o,i is a known value when a sequence is demapped to find a cell ID group and a frame boundary in the mobile station.
  • each element of a first sequence Co according to the second method of generating the secondary synchronization signal is a product of each element of the first short sequence w ⁇ and each element of the scrambling sequence P j ,o,i corresponding thereto.
  • k denotes an index of the even-numbered sub-carriers used for the secondary synchronization channel.
  • the scrambling sequence scrambling the second short sequence w1 is P j, i,i and S w o.
  • the scrambling sequence P j,i,i is a previously known value when a sequence is demapped to find a cell ID group and a frame boundary in the mobile station.
  • a plurality of short sequences are grouped into a plurality of short sequence group and the S w o may be determined by a short sequence group to which the first short sequence is assigned by grouping short sequences.
  • the S w o may be determined by a short sequence group to which the first short sequence is assigned by grouping short sequences.
  • the length of the first short sequence is 31 , there are 31 short sequences. Accordingly, by assigning the short sequences Nos. 0-7 to the group 0, the short sequences Nos. 8-15 to the group 1 , the short sequences Nos. 16-23 to the group 2, and the short sequences Nos. 24-30 to the group 3.
  • S w o is determined by mapping a length-31 scrambling code to the group to which the first short sequence number is assigned.
  • 31 short sequences may be classified into eight groups by grouping the numbers of the first short sequences having the identical remainder when we divide each number of short sequences by 8. That is, by assigning the short sequence number having the remainder of 0 when dividing the short sequence numbers by 8 to the group 0, the short sequence having the remainder of 1 when dividing the short sequence numbers by 8 to the group 1 , the short sequence having the remainder of 2 when dividing the short sequence numbers by 8 to the group 2, the short sequence having the remainder of 3 when dividing the short sequence numbers by 8 to the group 3, the short sequence having the remainder of 4 when dividing the short sequence numbers by 8 to the group 4, the short sequence having the remainder of 5 when dividing the short sequence numbers by 8 to the group 5, the short sequence having the remainder of 6 when dividing the short sequence numbers by 8 to the group 6, and the short sequence having the remainder of 7 when dividing the short sequence numbers by 8 to the group 7. Accordingly S w o is determined by mapping a length-31 scrambling code to the group to which the first short sequence number is assigned.
  • each element of a second sequence ci according to the second method of generating the secondary synchronization signal is a product of each element of the second short sequence w1 and each element of the scrambling sequences P j ,i , i and S w o corresponding thereto.
  • C 1 [Wi (O)SwO(O)P j1111 (O), Wi (I)SwO(I)P j1111 (I), - , wi ⁇ Swo ⁇ P j .i ⁇ m), - , WI (SO)S W O(SO)PJ 11 1 I(SO)]
  • m denotes the index of odd-numbered sub-carriers used for the secondary synchronization channel.
  • each element of a third sequence C 2 according to the second method of generating the secondary synchronization signal is a product of each element of the third short sequence w2 and each element of the scrambling sequence P j ,o, 2 corresponding thereto.
  • C 2 [w2(O)Pj,o, 2 (O), w2(1)Pj,o, 2 (1 ), -, w2(k)Pj, 0 ,2(k), -, w2(30)Pj, 0 , 2 (30)]
  • k denotes the index of even-numbered sub-carriers used for the secondary synchronization channel.
  • Scrambling sequences for scrambling a fourth short sequence are P j ,i, 2 and S W 2.
  • the scrambling sequence Pj 1 2 is a previously known value when a sequence is demapped to find the cell ID group and frame boundary in the mobile station.
  • the S w2 may be determined by a short sequence group to which the third short sequence is assigned by grouping short sequences.
  • the length of the third short sequence is 31 as well, there are 31 short sequences. Accordingly, by assigning the short sequences Nos. 0-7 to the group 0, the short sequences Nos. 8-15 to the group 1 , the short sequences Nos. 16-23 to the group 2, and the short sequences Nos. 24-30 to the group 3. Accordingly S w2 is determined by mapping a length-31 scrambling code to the group to which the third short sequence number is assigned. Furthermore, 31 short sequences may be classified into eight groups by grouping the numbers of the third short sequences having the identical remainder when we divide each number of short sequences by 8.
  • S W2 is determined by mapping a length-31 scrambling code to the group to which the third short sequence number is assigned.
  • each element of a fourth sequence C 3 according to the second method of generating the secondary synchronization signal is a product of each element of the fourth short sequence w3 and each element of the scrambling sequences Pj,i, 2 and S w2 corresponding thereto.
  • m denotes the index of odd-numbered sub-carriers used for the secondary synchronization channel.
  • Pj,i,i Pj,i,2.
  • the cell group and frame identify information are mapped to the combination of the first to fourth short sequences, and the number of descrambling hypotheses in the mobile station with respect to the scrambling of secondary synchronization channel determined by the cell identification sequence number of the primary synchronization channel is reduced to 3.
  • the cell group information is mapped to the combination of the first short sequence and the second short sequence
  • the frame synchronization information is mapped to the scrambling sequences (Pj,o,i, Pj,o,2, Pj,i,i, Pj,i,2) of the secondary synchronization channel determined by the cell identification sequence number of the primary synchronization channel.
  • the number of descrambling hypotheses of the mobile station with respect to the scrambling of the secondary synchronization channel determined by the cell identification sequence number of the primary synchronization channel is increased to 6.
  • the combination number of the cell group identification sequences is reduced to half, and the number of descrambling hypotheses of the mobile station with respect to the scrambling determined by the first and third short sequences is also reduced to half.
  • a first sequence determined by Equation 9 is allocated to every even-numbered sub-carrier of a first secondary synchronization channel
  • a second sequence determined by Equation 10 is allocated to every odd-numbered sub-carrier of the first secondary synchronization channel.
  • a third sequence determined by Equation 1 1 is allocated to every even-numbered sub-carrier of a second secondary synchronization channel
  • a fourth sequence determined by Equation 12 is allocated to every odd-numbered sub-carrier of the second secondary synchronization channel.
  • the first short sequence is scrambled with a first scrambling sequence having the length of 31 , which is determined by the cell identification sequence allocated to the primary synchronization channel
  • the second short sequence is scrambled with a second scrambling sequence having the length of 31 , which is determined by the cell identification sequence allocated to the primary synchronization channel.
  • the first short sequence and the second short sequence are scrambled with a scrambling sequence having the length of 62, which is determined by the cell identification sequence allocated to the primary synchronization channel.
  • P j, i is the scrambling sequence that scrambles the first short sequence and the second short sequence
  • P j,2 is the scrambling sequence that scrambles the third short sequence and the fourth short sequence.
  • the first sequence C 0 is as indicated in Equation 9
  • the second sequence ci is as indicated in Equation 10
  • the third sequence C 2 is as indicated in Equation 11
  • the fourth sequence C 3 is as indicated in Equation 12.
  • Equation 9 to Equation 12 k denotes the index of the even-numbered sub-carriers to be used for the secondary synchronization channel, and m denotes the index of the odd-numbered sub-carriers to be used for the secondary synchronization channel.
  • the frequency mapping unit 430 generates the downlink frame by mapping the secondary synchronization signal that are generated from the synchronization signal generating unit 420, and transmission traffic data to the time and frequency domains S530.
  • the OFDM transmitting unit 440 receives the downlink frame from the frequency mapping unit 430 and transmits the downlink frame through given transmission antenna S540.
  • a method of searching cells by the mobile station by using the downlink frame generated by the exemplary embodiment of the present invention will now be described with reference to FIG. 9 and FIG. 11.
  • FIG. 9 is a block diagram of an apparatus for searching cells according to the exemplary embodiment of the present invention
  • FIG. 10 is a flowchart illustrating a cell searching method according to a first exemplary embodiment of the present invention
  • FIG. 11 is a flowchart illustrating a cell searching method according to a second exemplary embodiment of the present invention.
  • the apparatus for searching the cells includes a receiving unit 710, a symbol synchronization estimating and frequency offset compensating unit 720, a Fourier transforming unit 730, and a cell ID estimating unit 740.
  • the receiving unit 710 receives the frames transmitted from the base station, and the symbol synchronization estimating and frequency offset compensating unit 720 filters the received signal by as much as a bandwidth allocated to the synchronization channel and acquires the symbol synchronization by respectively correlating the filtered received signal and a plurality of known primary synchronization signals, and compensates the frequency offset by estimating frequency synchronization (S810).
  • the symbol synchronization estimating and frequency offset compensating unit 720 respectively correlates the filtered received signal and the plurality of known primary synchronization signals and estimates a time of the largest correlation value as the symbol synchronization, and transmits a number of a primary synchronization signal having the largest correlation value to the cell ID estimating unit 740. At this time, the frequency offset may be compensated in the frequency domain after performing the Fourier transform.
  • the Fourier transforming unit 730 performs Fourier transform of the received signals on the basis of the symbol synchronization estimated by the symbol synchronization estimating and frequency offset compensating unit 720 (S820).
  • the cell ID estimating unit 740 estimates a cell ID group and frame synchronization by respectively correlating the Fourier transformed received signal with a plurality of known secondary synchronization signals S830.
  • the cell ID estimating unit 740 respectively correlates a plurality of secondary synchronization signals with the Fourier transformed received signal, and estimates the frame synchronization and the cell ID group by using a secondary synchronization signal that has the largest correlation value.
  • the plurality of secondary synchronization signals are given by applying Pj, 0,1, Pj ,0,2, Pj, 1,1 and Pj , 1,2 that are determined in accordance with a primary synchronization signal that corresponds to the number of a primary synchronization signal transmitted from the symbol synchronization estimating and frequency offset compensating unit 720 to Equation 5 to Equation 8, At this time, in the case that a synchronization channel symbol exists in one slot or one OFDM symbol within one frame, the symbol synchronization becomes frame synchronization, and therefore, it is not necessary to additionally acquire frame synchronization.
  • the cell ID estimating unit 740 estimates cell IDs by using the number of a primary synchronization signal transmitted from the symbol synchronization estimating and frequency offset compensating unit 720 and the estimated cell ID group S840. At this time, the cell ID estimating unit 740 estimates the cell ID with reference to a known mapping relationship between cell ID, the cell ID group, and a number of primary synchronization signal .
  • the estimated cell ID information may be verified by using scrambling sequence information included in the pilot symbol duration.
  • the receiving unit 710 receives a frame transmitted from the base station, and the symbol synchronization estimating and frequency offset compensating unit 720 filters the received signal by as much as a bandwidth allocated to the synchronization channel and acquires the symbol synchronization by respectively correlating the filtered received signal and a plurality of known primary synchronization signals, and compensates the frequency offset by estimating frequency synchronization S910.
  • the symbol synchronization estimating and frequency offset compensating unit 720 respectively correlates the filtered received signal and the plurality of known primary synchronization signals and estimates a time of the largest correlation value as the symbol synchronization, and transmits a plurality of correlation values of the plurality of known primary synchronization signals and filtered received signal to the cell ID estimating unit 740.
  • the frequency offset compensation may be performed in the frequency domain after Fourier-transformed.
  • the Fourier transforming unit 730 Fourier-transforms the received signal with reference to the symbol synchronization that is estimated by the symbol synchronization estimating and frequency offset compensating unit 720 S920.
  • the cell ID estimating unit 740 estimates cell IDs by using the plurality of correlation values transmitted from the symbol synchronization estimating and frequency offset compensating unit 720, and correlation values of the Fourier-transformed received signal and a plurality of known secondary synchronization signals S930.
  • the cell ID estimating unit searches a secondary synchronization signal having the largest correlation value by correlating each of the plurality of known secondary synchronization signals with the Fourier-transformed received signal for each of the plurality of known primary synchronization signals.
  • the plurality of secondary synchronization signals are given by applying Pj, 0 ,i, Pj,o,2, Pj,i,i and Pj, 1 >2 that are determined in accordance with the corresponding primary synchronization signal to Equation 5 to Equation 8.
  • the cell ID estimating unit 740 combines the correlation value of each known primary synchronization signal transmitted from the symbol synchronization estimating and frequency offset compensating unit 720 and the correlation value of the secondary synchronization signal having the largest correlation value for each of the plurality of known primary synchronization signals.
  • the cell ID estimating unit 740 estimates frame synchronization and a cell ID group by using a secondary synchronization signal having the largest combined value among the combined values of the correlation values of a primary synchronization signal and a secondary synchronization signal. In addition, the cell ID estimating unit 740 estimates a cell ID by using the primary synchronization signal having the largest combined value and the estimated cell ID group. At this time, the cell ID estimating unit 740 estimates the cell ID with reference to a known mapping relationship between the cell ID group, cell ID and the primary synchronization signal number.
  • the exemplary embodiment of the present invention can be not only implemented by the above-described apparatus and/or method, but can be implemented by, for example, a program that achieves the function corresponding to the configuration of the exemplary embodiment of the present invention and a recording medium in which the program is recorded. This will be easily implemented from the above-described exemplary embodiment of the present invention by those skilled in the related art.

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Abstract

La présente invention concerne un procédé de génération d'une trame descendante. Le procédé de génération de la trame descendante comprend : la génération d'une première séquence courte et d'une deuxième séquence courte indiquant des informations de groupe de cellules ; la génération d'une première séquence de brouillage et d'une deuxième séquence de brouillage déterminées par le signal de synchronisation principal ; la génération d'une troisième séquence de brouillage déterminée par un groupe de séquences courtes - un système de communication sans fil utilise une pluralité de séquences courtes et la pluralité de séquences courtes est groupée en une pluralité de groupes de séquences courtes - auquel la première séquence courte est attribuée ; le brouillage de la première séquence courte avec la première séquence de brouillage et le brouillage de la deuxième séquence courte avec la deuxième séquence de brouillage et la troisième séquence de brouillage ; et l'application sur un domaine de fréquences du signal de synchronisation secondaire qui comprend la première séquence courte brouillée et la deuxième séquence courte brouillée.
PCT/KR2008/004224 2007-07-20 2008-07-18 Procédé de génération de trame descendante et procédé de recherche de cellule WO2009014356A1 (fr)

Priority Applications (8)

Application Number Priority Date Filing Date Title
EP08778879A EP2137872B1 (fr) 2007-07-20 2008-07-18 Procédé de génération de trame descendante et procédé de recherche de cellule
BRPI0809496-9A BRPI0809496A2 (pt) 2007-07-20 2008-07-18 Métodos e equipamentos de geração de quadro de downlink e de busca de célula por meio de estação móvel em sistema de comunicação sem fio e mídias de gravação.
JP2010516932A JP5140728B2 (ja) 2007-07-20 2008-07-18 ダウンリンクフレーム生成方法及びセル探索方法
AU2008279973A AU2008279973B2 (en) 2007-07-20 2008-07-18 Method for generating downlink frame, and method for searching cell
CN2008800015550A CN101578810B (zh) 2007-07-20 2008-07-18 生成下行链路帧的方法和设备、与搜索小区的方法和设备
DE602008003424T DE602008003424D1 (de) 2007-07-20 2008-07-18 Verfahren zur erzeugung eines downlink-rahmens und verfahren zur zellensuche
AT08778879T ATE488067T1 (de) 2007-07-20 2008-07-18 Verfahren zur erzeugung eines downlink-rahmens und verfahren zur zellensuche
US12/488,286 US8331564B2 (en) 2007-07-20 2009-06-19 Method for generating downlink frame, and method for searching cell

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KR10-2007-0072837 2007-07-20
KR20070072837 2007-07-20
KR20070083915 2007-08-21
KR10-2007-0083915 2007-08-21
KR10-2008-0044413 2008-05-14
KR20080044413A KR20090009696A (ko) 2007-07-20 2008-05-14 하향링크 프레임 생성 방법 및 셀 탐색 방법
KR10-2008-0063389 2008-07-01
KR20080063389A KR100918501B1 (ko) 2007-07-20 2008-07-01 하향링크 프레임 생성 방법 및 셀 탐색 방법

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