(12) United States Patent
`Kwon et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,218,481 B2
`Jul. 10, 2012
`
`US0082l848lB2
`
`(54) METHOD OF TRANSMITTING DATA IN A
`MOBILE COMMUNICATION SYSTEM
`
`(75)
`
`Inventors: Yeong Hye0nKWon,Gyeor1ggi-do
`(KR); Seung Hee Han, Gyeonggi-‘do
`(KR); Hyun Hwa Park, Gyeonggi-do
`(KR); Dong Cheol Kim, Gyeonggi-do
`(KR)? H-V““ W” Lee’ Gy°°“ggi'd°
`(KR); Min Seok Noh, Gyconggi-do
`(KR)
`
`(73) Assignee: LG Electronics Inc., Seoul (KR)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U-Sec" 1540)) by 135 day5-
`
`(21) APPL N05
`
`12/303,947
`
`(22) PCT Filed:
`
`Jun. 8, 2007
`
`(86) PCT No.:
`§ 371 (c)(1),
`(2), (4) Datei
`
`PCT/KR2007/002784
`
`Jll1- 7, 2010
`
`(65)
`
`(87) PCT Pub. No.: WO2007/142492
`PCT Pub’ Date: Dec' 13’ 2007
`Prior Publication Data
`US 2010/0295436 A1
`N0V~ 25: 2010
`_
`_
`_
`_
`_
`Forelgn APPl1¢at1011 Prlorlty Data
`
`(30)
`
`Jun. 9, 2006
`Jun. 26, 2006
`(51)
`Int. CL
`H04L 12/50
`
`(KR) ...................... .. 10-2006-0052167
`(KR) ...................... .. 10-2006-0057488
`
`(2006.01)
`
`370/328; 370/329; 3701330
`(52) U.S. Cl.
`(58) Field of Classification Search ................. .. 370/328
`See application file for complete search history.
`_
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`2005/0286409 A1
`12/2005 Yoon etali
`2006/0153282 A1*
`7/2006 Jung et :11.
`
`................... .. 375/146
`
`JP
`
`JP
`
`FOREIGN PATENT DOCUMENTS
`04-035332
`2/1992
`
`ll-154929
`
`6/ 1999
`(Continued)
`
`OTHER PUBLICATIONS
`Chang el al: “Synchronization Method Based on a New Constant
`Envelop Preamble for OFDM Systems,” IEEE Transactions on
`Broadcasting,
`vol.
`51, No.
`1, Mar.
`2005,
`pp.
`139-143,
`XP-011127926.
`
`(Continued)
`Primary Examiner _ Jeffrey Pwu
`Assistant Examiner — Shripal Khajuria
`(74) Attorney, Agent, or Firm —Lee, Hong, Degerman,
`Kang & Waimey
`ABSTRACT
`(57)
`Disclosed is a data transmission method in a mobile commu-
`nicdation system. The dsga transmissiorlr methold throtigfi a
`co c scqucncc 111 a 1no 1 c comn1un1ca 1011 sys cm 1nc u cs
`grouping input data streams into a plurality ofblocks consist-
`ing of at least one bit so as to map each block to a correspond-
`ing signature sequence, multiplying a signature sequence
`stream, to which the plurality of blocks are mapped, by a
`specific Code sequence
`and transmitting the Signature
`Sequence Stream multiplied by the Specific Code Sequence to
`a receiver.
`
`16 Claims, 22 Drawing Sheets
`
`
`
`Single CAZAC sequence
`
`LE General CAZAC sequence of0
`
`Conjugate CAZAC sequence of I
`
`1
`
`APPLE 1001
`
`1
`
`APPLE 1001
`
`

`
`US 8,218,481 B2
`Page 2
`
`JP
`JP
`JP
`JP
`JP
`JP
`Vv'0
`VVO
`
`FOREIGN PATENT DOCUMENTS
`2000102067
`4/2000
`2001268051
`9/2001
`2003179576
`6/2003
`2004512728
`4/2004
`2004274794
`9/2004
`2005260337
`9/2005
`9637079 A1
`11/1996
`2/2001
`01/811909 A1
`
`W0
`WO
`WO
`
`2/2005
`2005/011128
`6/2005
`2005/055527
`2/2006
`2006/015108
`OTHER PUBLICATIONS
`
`Texas Instrurnents: “On Allocation of Uplink Pilot Sub-Channels in
`EUTRA SC-FDMA,” R1 -050822, 3GPP TSG-RANWG1 Ad Hoc on
`LTE, Aug. 2005, XP-002448008.
`
`* cited by examiner
`
`2
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 1 of 22
`
`US 8,218,481 B2
`
`FIG. 1
`
`Walsh generator
`
`
`
`
`
`Signature
`generator
`
`3
`
`

`
`U.S. Patent
`
`HNmM
`
`US 8,218,481 B2
`
`«SufismZ
`
`nofifimum
`
`
`
`uwou:23,»
`
`E32
`
`&@853323$W.
`
`
`
`Emaowcan«Em3:8:weOH...Omwe_a:w_m5:5%_a§,_nofifiumamammagmaHofiuursmuuflmawao<N<o
`
`S..aaafiam
`
`Nea
`
`4
`
`
`
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 3 of 22
`
`US 8,218,481 B2
`
`FIG. 3A
`
`L RACH
`
`
`n=0,1,2,3
`
`FIG. 3B
`
`LRACH
`
`
`I:]:[::]::]
`
`DPSK moduIation(DBPSK,DQPSK,D8PSK)
`
`FIG. 4A
`
`LRACH
`<
`
`Codedbit
`
`FIG. 4B
`
`L RACH
`
`
`5
`
`

`
`.~
`
`_
`
`_.__
`___
`
`_W
`
`é
`
`7
`
`mww
`
`_________
`
`mas
`
`6
`
`
`

`
`U.S. Patent
`
`Jul. 10 2012
`
`Sheet 5 of22
`
`<mGE
`
`7
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 6 of 22
`
`US 8,218,481 B2
`
`
`
`
`
`
`
`LongblockOFDMsymbol
`
`FIG.6B
`
`Subfiame
`
`
`
`ShortblockOFDMsymbol
`
`
`
`
`
`
`
`
`
`RACHsignaloffrequencydomain
`
`8
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 7 of 22
`
`US 8,218,481 B2
`
`"I,II[ i "-
`
` j
`
`
`
`B -8&1L at\
`. \\\\s
`E
`jmmwj” j §
`
`§ E §
`
`E
`
`:2
`-a.
`‘E’
`.—'§
`E
`
`gg
`
`191119
`V
`2 g
`
`E
`
`E
`
`IPMQIUEPIBRB
`
`z~
`
`E
`
`
`
`RACHburstduratiou
`
`113A191II}p.I13n9
`
`-!.
`
`..
`
`ixi.iIEi.
`
`.
`
`8.
`
`qgppmpuvq mezsfis
`
`E E
`
`TDM/FDM
`
`9
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 8 of 22
`
`US 8,218,481 B2
`
`
`
`
`
`oomunwum2%SE,Euéoommaomamufi
`
`3GE
`
`853%BE
`
`III-
`
`“Henson
`
`NW2.
`
`10
`
`10
`
`
`
`

`
`9 0
`
`V
`
`\
`
`,
`;_.g...:....., :
`‘I
`is‘ '='=E'
`:5
`2 2
`i
`i:i%:!§!:|§!-
`'-'-:-.-:,:I,...-
`s.~.
`.4
`.
`-..
`iii
`
`-I-3
`
`an
`CD
`
`9 F
`
`a
`
`3 .
`
`
`
`
`.§§rnln
`
`caII—l
`
`11
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 10 of 22
`
`US 8,218,481 B2
`
`FIG. 9
`
`Frame (10ms)
`
`RACH
`
`RACH
`
`12
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 11 of 22
`
`US 8,218,481 B2
`
`
`
`Ea$82..cuweuaomA
`
`EaSomoiA
`
`aane...a§.___m
`
`3ea
`
`
`
`
`
`mofioofixoofiteam
`
`BE5§§..=mEmaBEuso3Ea
`
`$83
`
`V
`
`13
`
`13
`
`
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 12 of 22
`
`US 8,218,481 B2
`
`FIG. 11
`
`Periodic
`prefix
`
`Repetitive sequence
`
`Repetitive sequence
`
`FIG. 12
`
`Single CAZAC sequence
`
`E] General CAZAC sequence of 0
`
`Conjugate CAZAC sequence of 1
`
`14
`
`14
`
`

`
`U.S. Patent
`
`US 8,218,481 B2
`
`
`cannonanon95.32Bu<N<o@803 86%2.582M.2:EM”zzzzzzzzz1:02?EnwasUses?SzmJuuuuuuuuuuuuuuI:
`
`m+2%_.&moimwoabtomm_
`
` B8558:H_:=o_._.mm=.E8.:«.3?fleaN+oozmwasacumen
`e.,=mS24...aofimsaoo%2:?83%M“new2us?»23§%._Mag
`
`
`
`
`
`mm8s{ms?2%;Mmowwm...ceu¢m.<oHmm_s%ms;
`
`
`
`EaaofimoM3H9.
`
`Eas
`
`15
`
`was855%anon2332
`
`
`aounmsmuooH.2:?Mann
`
`uuaofium9+aofimsmnooa03?«mom
`rto:_§%u.§33>“wonmeEo<N<o@553SE
`
`
`93aamaufiom§_...mwoauofiom8:mm.
`23%2Esaoflmomin8382mwasN4£83
`
`15
`
`
`
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 14 of 22
`
`US 8,218,481 B2
`
`FIG. 14
`
`Mixed CAZAC sequence having length of single CAZAC sequence
`
`El CAZAC1 sequence of0
`
`CAZAC2 sequence of 1
`
`16
`
`

`
`U.S. Patent
`
`MJ
`
`fl.
`
`US 8,218,481 B2
`
`wow;
`
`52m
`
`Ema
`
`Sam
`
`\
`
`HRSmMmNB_.a§._3:EB0,9.2»€53..8uomoawom
`
`
`
`
`vfiumSinai_#83weJcowomanamenEamnuaomm:oomozvumfiaaufi
`
`HeonmmmomMwm
`
`0wH€93I?wR»_.
`
`
`
`mm.mmocooummag:§mo.__#ow_>_#.#_..w.__rWm_m_98:2393%25Scam.mE=uE
`
`4...somea82;?zosflocuw23.2.8:awfizaufionoEmu=n“wu:8mNu_oo_nEo
`
`
`17
`
`
`
`men:9.2».mE:oE
`
`
`
`#003w=mEo%o:oo
`
`._oEmsew&==uE
`
`
`
`M83w:mEo%ubcu
`
`
`
`A:oonuawum%.E=uE
`
`mum.23me
`
`3ea
`
`Sim
`
`17
`
`
`
`
`
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 16 of 22
`
`US 8,218,481 B2
`
`FIG. 16
`
`18
`
`18
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 17 of 22
`
`US 8,218,481 B2
`
`
`
`u=_m>uvcuun
`
`
`
`
`
`M033some.uO
`
`
`
`
`
`noEmmaamenEnmuuauaEuuauawumQiufi
`
`
`
`
`
`85.52B:m_Eanew__uE3.Hauunoawomamaniac
`
`
`
`am:maaiimamBaaScam
`
`aaufioaowEaofinuuw
`
`
`
`aewfionomum>u=o=_.u.—._sum:
`
`w..E__masonSoufiufim
`
`
`
`N“.85..Buuaunwoa©.=EE
`
`Sta
`
`19
`
`5as
`
`szm
`
`w==.:o._mu.=8
`
`8%SimginLxucfi
`
`
`
`..,_8Euamuaommuuou
`
`
`
`.._aE9.9»>.E=uE
`
`
`
`we5es.»fiwnofi
`
`
`
` =xuofias335:3»$353
`
`19
`
`
`
`
`
`
`

`
`U.S. Patent
`
`uJ
`
`2m
`
`US 8,218,481 B2
`
`
`
`=.§=ocQEWF
`
`3ea
`
`N.a__...amE552WTVTVTVTLl2“%2mm“EmNManiHfies
`...1fl,..%é..._._aQ32:
`
`2_§lLAaivT|...+flV_
`
`
`>o=o=wuE.wB,IAvacufinmHobv85:umwAmzommfinmobmounoswum
`0Enfiow
`mm.mANnofimnmSumoonuawumQ:cE...=_D.S_:_
`
`ouaoasm
`
`20
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 19 of 22
`
`US 8,218,481 B2
`
`FIG. 19
`
`S1901
`
`S1903
`
`S1905
`
`and receiving signal
`
`‘
`Sequence reoeptton
`
`V
`v
`~
`getfiggfiglg CAZAC
`‘ q
`
`Full-correlation using
`detected CAZAC ID
`
`S1907
`[
`S1909
`
`Decoding of data order
`and bit value from
`detected peak values
`
`
`
`
`Detection ofpeak values
`from correlation result
`
`
`
`S1911
`
`data estimation
`
`21
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 20 of 22
`
`US 8,218,481 B2
`
`FIG. 20A
`
`Access-preamble (—1message)
`
`
`S2001
`
`S2003l
`
`t"
`
`T’
`
`'
`
`' f
`
`Allocation of uplink data resource
`
`S2007
`
`
`
`Transmission of uplink data
`
`S2005
`
`User equipment
`
`FIG. 20B
`
`Access preamble
`
`S2011
`
`S2015
`
`
`
`h d 1'
`'
`so e u mgreques
`
`i
`
`Timing information and allocation of scheduling request resource
`
`Allocation of uplink data resource
`
`S2019
`
`Transmission of uplink data
`
`22
`
`S2013
`
`S2017
`
`22
`
`

`
`U.S. Patent
`
`Jul. 10, 2012
`
`Sheet 21 of 22
`
`US 8,218,481 B2
`
`
`
`35.52u<N<o33
`
`
`
`5%Ema”a___a_m
`
`23
`
`

`
`U.S. Patent
`
`HJ
`
`2
`
`22f0
`
`US 8,218,481 B2
`
`'1
`
`IIII F
`
`I
`
`,._..__.._.___...._———.—
`
`
`
`
`
`EmaEeawse..85:3“9U<N<U3%wB:m$E
`
`mmea
`
`_
`
`a__WWuufifimafih“_I._.lllllllllllllllllllllllllllllllllllllllllll.lIIIIF
`
`
`,H__2__MHu
`
`t_I...%.W3h_85:amSun_4S__2__
`n.1}...I:uuuuuu-1.
`
`
`24
`
`
`

`
`US 8,218,481 B2
`
`1
`METHOD OF TRANSMITTING DATA IN A
`MOBILE COMMUNICATION SYSTEM
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is the National Stage filing under 35
`U.S.C. §371 of International Application No. PCT."KR07/
`02784, filed on Jun. 8, 2007, which claims the benefit of
`earlier filing date and right of priority to Korean Application
`Nos. 10-2006-0052167, filed on Jun. 9, 2006, and 10-2006-
`0057488, filed on Jun. 26, 2006.
`
`TECHNICAL FIELD
`
`The present invention relates to a mobile communication
`system, and more particularly, to a method of expanding a
`code sequence, a structure of a random access charmel and a
`method of transmitting data in a mobile communication sys-
`tem.
`
`BACKGROUND ART
`
`A user equipment uses a random access channel (RACH)
`to access a network in a state that the user equipment is not
`uplink synchronized with a base station. A signal having
`repetitive characteristic in a time domain is used in the ran-
`dom access channel, so that a receiver easily searches a start
`position of a transmission signal. In general, the repetitive
`characteristic is realized by repetitive transmission of a pre-
`amble.
`
`A representative example of a sequence for realizing the
`preamble includes a CAZAC (Constant Amplitude Zero Auto
`Correlation) sequence. The CAZAC sequence is expressed by
`a Dirac-Delta function in case of auto-correlation and has a
`
`constant value in case of cross-correlation. In this respect, it
`has been estimated that the CAZAC sequence has excellent
`transmission characteristics. However, the CAZAC sequence
`has limitation in that maximum N—1 number of sequences
`can be used for a sequence having a length of N. For this
`reason, a method for increasing available bits ofthe sequence
`while maintaining the excellent transmission characteristics
`is required.
`Meanwhile, there are provided various methods for trans-
`mitting data from a random access channel by using the
`CAZAC sequence. Of them, the first method is to directly
`interpret CAZAC sequence ID to message information.
`Assuming that data to be transmitted is a preamble, if a
`sufficient number of sequences that can be used as the pre-
`amble are provided, message passing can be performed with
`only CAZAC sequence ID without additional manipulation.
`However, since a method of transmitting additional inforrna-
`tion should be considered in an actual synchronized RACH,
`problems occur in that there is difliculty in realizing a suffi-
`cient number of CAZAC sequence sets, and the co st required
`for search of a receiver increases.
`
`The second method is to simultaneously transmit CAZAC
`sequence and Walsh sequence by using a code division mul-
`tiplexing (CDM) mode. In this case, CAZAC sequence ID is
`used as user equipment identification information, and the
`I/Valsh sequence transmitted in the CDM mode is interpreted
`as message information. FIG. 1 is a block schematic View
`illustrating a transmitter for realizing the second method.
`However,
`the second method has limitation in that even
`though the Walsh sequence is added to the CAZAC sequence,
`bits of message that can additionally be obtained are only
`log2N bits when the Walsh sequence has a length of N.
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`
`The third method is to transmit CAZAC sequence and
`Walsh sequence in such a way to mix the Walsh sequence with
`the CAZAC sequence. In this case, CAZAC sequence ID is
`used as user equipment identification information, and the
`Walsh sequence is interpreted as message information. FIG. 2
`is a block diagram illustrating a data processing procedure at
`a transmitter for realizing the third method. However, accord-
`ing to the third method, since the Walsh sequence acts as noise
`in detection of the CAZAC sequence to cause difficulty in
`detecting sequence ID, there is limitation in that repetitive
`sequences should be transmitted to prevent
`the Walsh
`sequence from acting as noise in detection of the CAZAC
`sequence.
`The fourth method is to either give orthogonality between
`blocks constituting a corresponding sequence by multiplying
`an exponential term by a CAZAC sequence or directly apply
`data modulation such as DPSK, DQPSK, DSPSK, etc. In this
`case, CAZAC sequence ID is used as user equipment identi-
`fication information, and the modulated sequence is demodu-
`lated and then used as message information. FIG. 3A illus-
`trates data modulation according to the former method ofthe
`fourth method, and FIG. 3B illustrates data modulation
`according to the latter method of the fourth.
`Furthermore,
`the fifih method is to transmit CAZAC
`sequence by attaching a message part
`to the CAZAC
`sequence. FIG. 4A illustrates the case where a message
`(coded bit) is attached to the CAZAC sequence used as a
`preamble, and FIG. 4B illustrates the case where a message
`(coded bit) is attached to a sequence consisting of a predeter-
`mined number of blocks to which orthogonality is given.
`However, the fourth method and the fifth method have a
`problem in that they are susceptible to change of charmel
`condition.
`
`DISCLOSURE OF THE INVENTION
`
`Accordingly, the present invention has been suggested to
`substantially obviate one or more problems due to limitations
`and disadvantages of the related art, and an object of the
`present invention is to provide a method of transmitting and
`receiving message between a user equipment and a base
`station by using a long sequence to maximize time/frequency
`diversity and alleviating performance attenuation due to
`channel.
`
`Another object of the present invention is to provide a
`method of transmitting data through a code sequence in a
`mobile communication system, in which the quantity of data
`can be increased and the transmitted data becomes robust to
`
`noise or channel change.
`Still another object of the present invention is to provide a
`method of suggesting a structure of an efficient random
`access channel in a multi-carrier system.
`Further still another object of the present invention is to
`provide a method ofminimizing access time of a user equip-
`ment to a random access channel in a mobile communication
`system.
`To achieve these obj eels and o lher advanl.ages and in accor-
`dance with the purpose of the invention, as embodied and
`broadly described herein, a data transmission method through
`a random access channel in a mobile communication system
`comprises generating a new code by multiplying a code
`sequence by an exponential sequence, and transmitting the
`new code sequence to a receiving side.
`In another aspect ofthe present invention, a data transmis-
`sion method by using a code sequence in a mobile commu-
`nication system comprises conjugating at least one element
`included in at least one block of a code sequence divided by at
`
`25
`
`25
`
`

`
`US 8,218,481 B2
`
`3
`least two blocks to indicate predetermined information, and
`transmitting the code sequence, in which the at least one
`block is conjugated, to a receiving side.
`In still another aspect ofthe present i.r1vention, a data trans-
`mission method by using a code sequence in a mobile com-
`munication system generating a second code sequence indi-
`cating predetermined information by combining at least two
`first code sequences mapped with at least one information bit,
`respectively, and transmitting the second code sequence to a
`receiving side.
`In further still another aspect of the present invention, a
`code sequence transmission method in a mobile con1n1unica-
`tion system comprises generating a combination code
`sequence by combining a base code sequence to at least one
`code sequence obtained by circular shift of the base code
`sequence, and transmitting the combination code sequence to
`a receiving side.
`In further still another aspect of the present invention, a
`code sequence transmission method in a mobile communica-
`tion system generating a repetitive code sequence by repeat-
`edly concatenating a first code sequence at least one or more
`times, generating a cyclic prefix (CP) by copying a certain
`part of a rear end of the repetitive code sequence and concat-
`enating the copied part to a front end of the repetitive code
`sequence, and transmitting the repetitive code sequence, in
`which lhe CP is generated, to a receiving side.
`In further still another aspect of the present invention, a
`method of allocating a random access charmel (RACH) in a
`multi-carrier system comprises allocating a random access
`channel to each of at least two consecutive frames in a way
`that frequency bands ofthe random access channels allocated
`to the at least two consecutive frames are not overlapped with
`each other, and transmitting allocation information of the
`random access channels allocated to the at least two consecu-
`
`tive frames to at least one user equipment.
`In further still another aspect of the present invention, a
`data transmission method through a code sequence in a
`mobile communication system mapping each of a plurality of
`blocks having at least one bit of a input data stream, respec-
`tively to a corresponding signature sequence, multiplying a
`signature sequence stream, to which the plurality of blocks
`are mapped, by a specific code sequence, and transmitting the
`signature sequence stream multiplied by the specific code
`sequence to a receiving side.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates an example ofa data transmission method
`through a random access channel in an OFDMA system
`according to the related art;
`FIG. 2 illustrates another example of a data transmission
`method through a random access charmel in an OFDMA
`system according to the related art;
`FIG. 3A and FIG. 3B illustrate still another example of a
`data transmission method through a random access charmel in
`an OFDMA system according to the related art;
`FIG. 4A and FIG. 4B illustrate further still another example
`ofa data transmission method through a random access chan-
`nel in an OFDMA system according to the related art;
`FIG. 5 illustrates an example of a structure of a random
`access channel used iii an OFDMA system;
`FIG. 6A and FIG. 6B illustrate examples of sending an
`RACII signal in a time domain or a frequency domain based
`on a structure of a random access charmel of FIG. 5;
`FIG. 7 illustrates another example of a structure of a ran-
`dom access channel used in an OFDMA system;
`
`4
`
`l0
`
`15
`
`FIG. 8A and FIG. 8B illustrate still another example of a
`structure of a random access channel used in an OFDMA
`
`system;
`FIG. 9 illustrates a structure of a random access charmel
`according to one embodimenl of the present. invention;
`FIG. 10 illustrates a structure of a random access charmel
`
`of a sub-frame to which RACH pilot is allocated;
`FIG. 11 illustrates a repetitive structure of a preamble
`according to one embodiment of the present invention;
`FIG. 12 is a structural view of unit data to illustrate one
`
`embodiment ofthe present invention, which transmits data by
`using a code sequence expanded through conjugation;
`FIG. 13 is a flow chart illustrating a procedure of receiving
`and decoding data transmitted in a code sequence expanded
`through conjugation in accordance with one embodiment of
`the present invention;
`FIG. 14 is a structural view of unit data to illustrate one
`
`embodiment ofthe present invention, which transmits data by
`using a code sequence expanded through grouping;
`FIG. 15 is a flow chart illustrating a procedure of receiving
`and decoding data transmitted in a code sequence expanded
`through grouping;
`FIG. 16 is a structural view of unit data to illustrate one
`
`25
`
`30
`
`embodiment ofthe present invention, which transmits data by
`using a code sequence expanded through grouping and delay
`processing;
`FIG. 17 is a How charl. illustrating a procedure ofreceiving
`and decoding data transmitted in a code sequence expanded
`through grouping and delay processing;
`FIG. 18 is a structural view of unit data to illustrate one
`
`embodiment ofthe present invention, which transmits data by
`using a code sequence expanded through PPM modulation;
`FIG. 19 is a flow chart illustrating a procedure of receiving
`and decoding data transmitted in a code sequence expanded
`through PPM modulation;
`FIG. 20A and FIG. 20B are flow charts illustrating a pro-
`cedure of perfonning synchronization in a random access
`channel in accordance with a data transmission method ofthe
`
`present invention;
`FIG. 21 illustrates a method of transmitting data to a
`receiver through a signaling channel in accordance with one
`embodiment of the present invention; and
`FIG. 22 illustrates an example of a receiver and a transmit-
`ter for transmitting a preamble and data through RACH, SCH
`or other charmel in accordance with one embodiment of the
`
`present invention.
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`
`Hereinafter, structures, operations, and other features of
`the present invention will be understood readily by the pre-
`ferred embodiments of the present invention, examples of
`which are illustrated in the accompanying drawings.
`A random access channel (RACH) is used to allow a user
`equipment to access a network in a state that the user equip-
`mcnl is not uplink synchronized wilh a base sla lion. A random
`access mode can be classified into an initial ranging access
`mode and a periodic ranging access mode depending on an
`access mode to network. According to the initial ranging
`access mode, the user equipment acquires downlink synchro-
`nization and first accesses a base station. According to the
`periodic ranging access mode, the user equipment connected
`with a network accesses the network if necessary. The initial
`ranging access mode is used to allow the user equipment to
`synchronize with the network while accessing the network
`and receive its required ID from the network. The periodic
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`26
`
`26
`
`

`
`US 8,218,481 B2
`
`5
`ranging access mode is used to initiate a protocol to receive
`data from the base station or when a packet to be transmitted
`exists.
`
`In particular, the periodic ranging access mode can be
`classified into two types in the 3GPP l.'l'Il (long term evolu-
`tion) system, i.e., a synchronized access mode and a non-
`synchronized access mode. The synchronized access mode is
`used ifan uplink signal is within a synchronization limit when
`the user equipment accesses the RACH. The non-synchro-
`nized access mode is used if the uplink signal is beyond the
`synchronization limit. The non-synchronized access mode is
`used when the user first accesses the base station or synchro-
`nization update is not performed after synchronization is
`performed. At this time, the synchronized access mode is the
`same as the periodic ranging access mode, and is used when
`the user equipment accesses the RACH for the purpose of
`notifying the base station of the change status of the user
`equipment and requesting resource allocation.
`On the other hand, the synchronized access mode alleviates
`limitation ofa guard time in the RACH by assuming that the
`user equipment does not depart from uplink synchronization
`with the base station. For this reason, much more tirne-fre-
`quency resources can be used. For example, a considerable
`amount of messages (more than 24 bits) may be added to a
`preamble sequence for random access in the synchronized
`access mode so that both the preamble sequence and the
`messages may be transmitted together.
`A structure of the RACH, which performs a unique func-
`tion of the RACH while satisfying the aforementioned syn-
`chronized and non-synchronized access modes will now be
`described.
`
`FIG. 5 is a diagram illustrating an example of a structure of
`a random access channel (RACH) used in an OFDMA sys-
`tem. As shown in FIG. 5, it is noted that the RACH is divided
`into N number of sub -frames on a time axis and M number ol‘
`
`frequency bands on a frequency axis depending on a radius of
`a cell. Frequency in generation of the RACH is determined
`depending on QoS (Quality of Service) requirements in a
`medium access control (MAC) layer. In general, the RACH is
`generated per certain period (several tens of milliseconds
`(ms) to several hundreds ofms). In this case, frequency diver-
`sity effect and time diversity effect are provided in generating
`several RACHs and at the same time collision between user
`
`equipments which access through the RACH is reduced. The
`length of the sub-frame can be 0.5 ms, 1 ms, etc.
`In the RACH structure as shown in FIG. 5, a random
`sub-frame will be referred to as a time-frequency resource
`(TFR) which is a basic unit of data transmission. FIG. 6A is a
`diagram illustrating a type of sending a random access signal
`to the TFR in a time domain, and FIG. 6B illustrates a type of
`sending a RACH signal in a frequency domain.
`As shown in FIG. 6A, if a random access signal is gener-
`ated in a time domain, the original sub-frame structure is
`disregarded and the signal is aligned through only the TFR.
`By contrast, as shown in FIG. 6B, in case ofthe synchronized
`random access mode, the sub-frame structure is maintained in
`the frequency domain and at the same time a random access
`signal to be transmitted to sub-carriers ofeach OFDM symbol
`is generated. Accordingly, orthogonality can be maintained
`between respective blocks constituting TFR, and channel
`estimation can easily be performed.
`FIG. 7 is a diagram illustrating another example of a struc-
`ture of RACH used in an OFDMA system. As shown in FIG.
`7, it is noted that a preamble ‘b’ and a pilot ‘a’ are partially
`overlapped in a TDM/'FDM mode and a TDM mode of RACH
`burst duration of an attached wideband pilot. It is also noted
`that a pilot ‘a’ and a pilot ‘b’ are simultaneously overlapped
`
`l0
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`with a preamble ‘a’ and the preamble ‘b’ in the TDM/FDM
`mode and the TDM mode of an embedded wideband pilot. In
`other words, it is designed that a preamble and a pilot are
`together transmitted through the RACH, so that message
`decoding is easily performed through channel estimation if
`message is added to the RACH. Alternatively, a wideband
`pilot is used so that channel quality information (CQI) of a
`total of RACH bands can be acquired in addition to a pre-
`amble band of the RACH.
`
`FIG. 8A and FIG. 8B are diagrams illustrating another
`examples of a structure of the RACH used in the OFDMA
`system,
`As shown in FIG. 8A, a preamble is transmitted for a
`predetermined time period through a frequency band, and a
`short block duration is provided at a certain period so that a
`pilot for decoding a preamble is transmitted to a correspond-
`ing short block. At this time, the pilot transmission is per-
`formed through a part of a total of frequency bands (trans-
`mission through 25 sub-carriers corresponding to a middle
`band of a total of 75 sub-carriers), so that tl1e pilot can be
`transmitted to a specific user equipment under a multi-access
`environment.
`
`Furthermore, as shown in FIG. 8B, a message to be trans-
`mitted and a pilot for decoding the message are multiplexed
`and continue to be transmitted through some frequency bands
`(for example, 25 middle sub-carrier bands of a total of 75
`sub-carrier bands) selected from a total of frequency bands.
`Accordingly, respective user equipments which perform
`multi-access can be identified by allocating some frequency
`bands at different frequencies.
`FIG. 9 is a diagram illustrating a structure of RACH
`according to one embodiment of the present invention.
`Generally, frequency in generation of the RACH is deter-
`mined depending on QoS requirements in a MAC layer. The
`RACH is generated at a variable period (several ms to several
`hundreds of ms) depending on requirements of a cell. The
`RACH can be generated in a time domain or a frequency
`domain as described above with reference to FIG. 6A and
`FIG. 6B. In the embodiment of FIG. 9, the structure of the
`RACH corresponds to the case where a random access signal
`is generated in the frequency domain.
`Referring to FIG. 9, in this embodiment, to overcome a
`drawback of a long interval required for retry when the user
`equipment fails to access the RACH, a corresponding RACH
`resource is dispersed in each frame within one period if fre-
`quency in generation of the RACH and the quantity of over-
`head are determined. The number of frames included in one
`
`period can freely be determined as occasion demands. At this
`time, it is preferable that the RACH is divisionally arranged
`so as to be uniformly distributed for each frequency band with
`respect to a plurality of frames constituting one period. How-
`ever, position on the time axis may be changed without
`change of position on the frequency axis and vice versa
`depending on specific requirements (synchronized action or
`decrease of inter-cell interference) of a cell or ifa system band
`is small. Also, arrangement of any one of frequency and time
`may be changed to obtain the minimum interval between the
`RACHs arranged in each frame.
`In the embodiment of FIG. 9, the network should notify the
`user equipment of position information of the allocated
`RACH resource. In other words, the network can notify each
`user equipment of frequency and time information occupied
`by the RACH resource allocated for each frame included in
`one period, and each user equipment can try random access
`through the allocated RACH resource by using the position
`information from the network. The position information of
`the RACH resource of each frame can be expressed by sub-
`
`27
`
`27
`
`

`
`US 8,218,481 B2
`
`7
`carrier offset, the number of sub-carriers, timing offset, and
`the number of symbols. However, if the RACH information
`on each frame is expressed by the above four parameters, it
`may be undesirable in that the quantity ofthe information can
`be increased. Accordingly, a method of decreasing the quan-
`tity ofthe information for expressing the position information
`of the RACH allocated on each frame is required. The posi-
`tion information of the RACH can be transmitted through a
`broadcast charmel (BCH) or other downlink control charmel.
`As one method, a method using a hopping pattern may be
`considered. The hopping pattern means a pattern consisting
`of infonnation indicating frequency domains of the RACH
`resource allocated to each frame within one period. In other
`words,
`in the embodiment of FIG. 9, since the RACH
`resource is divisionally arranged so as to be uniformly dis-
`tributed for each fiequency band with respect to a plurality of
`frames constituting one period, an indicator which indicates a
`frequency band that can be allocated to each fiame as the
`RACH resource is previously determined, and the frequency
`band of the RACH resource allocated to each frame withi11
`
`5
`
`10
`
`15
`
`25
`
`one period can be notified through a pattern of the indicator
`which indicates a corresponding frequency band.
`For example, if four frames are used as one period in a
`system which uses a total ofbands of 10 MHZ, the position of
`the RACH includes sub -bands having an interval of 2.5 MHZ
`as one RACH frequency band (band smaller than 1.25 MHz
`or 2.5 Mllz). At this time, a total of bands consist of four
`sub-bands, wherein the respective sub-bands are designated
`by indicators, which indicate each sub-band, as 1, 2, 3 and 4
`in due order from a high frequency band to a low frequency 30
`band. In this way, the frequency band position information of
`the RACH resource allocated to all frames within one period
`can be expressed by patterns configured by the above indica-
`tors, for example 2, 3, 1, 4. The hopping pattern may be
`conligured differently or equally depending on each lrame.
`Time information of the RACH resource allocated to each
`
`35
`
`40
`
`frame within one period can generally be expressed by timing
`offset and the number of symbols. At this time, at least any
`one of the timing offset and the number of symbols may be
`fixed to decrease the quantity of the information. For
`example, if it is previously scheduled that the timing offset
`and the number of symbols for the RACI I resource of each
`frame are fixed, the network only needs to transmit the hop-
`ping pattern to notify the user equipment of the position
`information of the RACH resource of all frames within one 45
`period.
`If each sub-band is narrow or considering influence of
`interference between user equipments, hopping patterns for
`all frames may be set equally. In this case, the network only
`needs to notify the user equipment of a frame period.
`Hereinafter, the procedure oftransmitting uplink data from
`the user equipment to the base station by using the structure of
`the RACH as shown in the embodiment of FIG. 9 will be
`
`50
`
`In this case, data transmission is performed
`described.
`through the RACH among reverse common charmels consist-
`ing of a plurality of frames.
`First ofall, the user equipment tries to access the dispersed
`RACH included in the current frame to transfer its informa-
`
`55
`
`tion