(12) United States Patent
`(10) Patent N0.:
`US 8,265,096 B2
`
`Zheng et al.
`(45) Date of Patent:
`Sep. 11, 2012
`
`U8008265096B2
`
`(54) METHOD FOR CONSTRUCTING FRAME
`STRUCTURES
`
`-
`(73)
`
`c
`.
`.
`Inventors: Yan-Xiu Zheng, Shulin (TW); Ren-Jr
`C hen, Hsmchu (TVV); Chang-Lung
`Hsiao, Hsinchu (TW'); Pang-An Ting,
`pongyuan (Tw)
`.
`Industrial chhnologvacscarcli
`lnStltUtea 11511101111 (“’0
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`7
`-
`;,
`U‘S'C‘ 154(1)) by 383 d3”
`(21) App1~N0~I 120631855
`
`.
`(73) ASSIgnee:
`
`( * ) Notice:
`
`22
`
`)
`(
`(65)
`
`_
`(60)
`
`F] d:
`1 e
`
`J l. 7. 2008
`u
`'
`Prior Publication Data
`Us 2009/0016371 A1
`Jan. 15, 2009
`
`Related U.S. Application Data
`.
`,
`.
`.
`,
`Prov1sronal application No. 60/929,798, filed on Jul.
`12, 2007, provisional application No. 60/973,157.
`filed on Sep. 17, 2007.
`
`,
`
`51
`
`(
`
`Int. Cl.
`(2006.01)
`H04.] 3/24
`370/473; 370/474; 370/476; 455/448
`(52) U.S. Cl.
`(58) Field of Classification Search ,,,,,,,,,,,,,,,,,, 370/329
`370/478, 491, 349, 469, 473, 474, 476, 338;
`375/1485 354
`See application file for complete search history.
`
`(56)
`
`References Cited
`US. PATENT DOCUMENTS
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`l'rachewsky ............... 370/338
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`7,809,020 B2 * 10/2010 Douglas et al.
`............... 370/474
`8,077,592 Bl
`l2/20ll VVlit
`‘
`t
`11
`
`370/338
`3/2002 H(e: is me a.tttttttt
`2002/0034172 A1 .11
`
`,, 370/338
`2004/0223478 A1 * 11/2004 Fischer et a1,
`2005/0063345 Al
`3/2005 Wu e1 211
`2005/0111529 A1 1‘
`5/2005 Bradley ........................ 375/148
`2005/0 l 804m Al
`8/2005 Kao et ali
`2006/0018279 A1
`1/2006 A
`Val
`t
`1.
`2006/0227778 A1
`10/2006 £52211. 0 a
`370/349
`2007/0097946 A1 *
`5/2007 Mujtaba
`..
`2007/0155315 A1
`7/2007 Lee et al.
`370/49l
`2007/0 l 89 I49 Al *
`8/2007 Terabe
`
`
`
`370/478
`2008/0095195 A1 *
`4/2008 Ahmadi et a .
`2008/0285513 A1* 11/2008 Jung et al.
`. .........
`,, 370/329
`1/2009 Zheng et 31
`2009/0016371 A1
`........... 370/329
`2009/0116435 A1 "‘
`5/2009 Koorapatyet al.
`20100222504 Al
`9/2011 Ma et a1
`2012/0140730 AU"
`6/2012 Marks et al
`............... 370/330
`
`..
`
`FOREIGN PATENT DOCUMENTS
`WO 2006/092852
`*
`8/2006
`WO
`* Cited by “Miller
`
`Primary Examiner 7 Jeffrey M Rutkowski
`(74) Anornev, Agent, or Firm 7 Alston & Bird LLP
`'
`
`ABSTRACT
`(57)
`A method ofconstructing a frame structure for data transmis-
`Sion, tie met 10 com risin generatin a
`rst section com-
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`prising data configured in a first formal compatible with a first
`communication system, generating a second section follow-
`ing the first section, the second section comprising data con-
`figured ina second format compatible witha second commu-
`nieation system, wherein the second format is different from
`the first format, generating at lea st one non—data section con-
`taining information describing an aspect of data in at least one
`ofthe first section and the second section, and combining the
`first section, the second section and the at least one lion-data
`section to form the frame structure.
`
`43 Claims, 6 Drawing Sheets
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`ZyXEL Communications Corporation Ex. 1001
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`ZyXEL Communications Corporation Ex. 1001
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`

`

`U.S. Patent
`
`Sep. 11,2012
`
`Sheet 1 of6
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`US 8,265,096 B2
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`

`

`U.S. Patent
`
`Sep. 11,2012
`
`Sheet 2 of6
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`US 8,265,096 B2
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`ZyXEL Communications Corporation Ex. 1001
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`

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`U.S. Patent
`
`Sep.11,2012
`
`Sheet30f6
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`US 8,265,096 B2
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`U.S. Patent
`
`Sep. 11,2012
`
`Sheet 4 of6
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`US 8,265,096 B2
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`U.S. Patent
`
`Sep. 11,2012
`
`Sheet 5 0f6
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`US 8,265,096 B2
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`U.S. Patent
`
`Sep. 11, 2012
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`Sheet 6 0f 6
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`US 8,265,096 B2
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`US 8,265,096 B2
`
`1
`METHOD FOR CONSTRUCTING FRAME
`STRUCTURES
`
`CROSS—REFERENCE TO RELATED
`APPLICATION
`
`This application claims the benefit of U.S. Provisional
`Application No. 60/929,798, entitled “Frame Structure in
`Wireless Communication Systems,” filed Jul. 12, 2007, and
`60/973,157. entitled “Bandwidth Scalable OFDMA Frame
`Structure,” filed Sep. 17, 2007. These applications are hereby
`incorporated by reference in their entirety.
`BACKGRO U Nl.)
`
`10
`
`2
`and a lower row of the data interlaced with the pilot symbols
`24-1, represented by blocks marked with X. In some appli-
`cations such placement of information may be inflexible to
`bandwidth sealing due to the fixed-length preambles 10'-1
`and/or 10‘—2 and the often unusable guard bands 22—1 and
`22—2. Moreover, the placement may be susceptible to a Dop-
`pler effect in a high mobility scenario because the placement
`may be usually designed with a relatively large symbol
`period, which in tum may induce relatively short carrier spac -
`ing and less dense pilot symbol placement. Moreover, the
`limitation on pilot symbol placement may cause channel esti-
`mation error at a receiving end because of insufficient infor-
`mation provided for channel estimation.
`SUMMARY
`
`
`
`The present invention generally relates to orthogonal fre-
`quency—division multiple access (OFDMA) systems, and
`more particularly, the present invention relates to methods for
`constructing frame structures in OFDMA systems.
`Orthogonal
`Frequency Division Multiple Access
`(OFDMA) is a multiple access scheme for transmitting data
`in different subcarriers in a chamiel, wherein the data may
`come from different users and may be transmitted in disjoint
`subsets of sub—channels in a transmission bandwidth. The
`orthogonality property among the subcarriers may allow
`simultaneous transmission of data from different users with-
`out interference from one other. The multiple access scheme
`ofthe OFDMA may generally be applied in various conunu-
`nication systems, such as those defined in IEEE standard
`802.16e (“legacy system” hereafter) and IEEE standard
`802.16m (“new system” hereafter). The new system defined
`in the IEEE standard 802.16m may be required to provide
`enhanced spectrum efficiency, higher speed tolerance and full
`awkward compatibility with the legacy system defined in the
`EEE standard 802.16e.
`FIG. 1 is a diagram illustrating an OFDMA ,rarne structure
`under the IEEE 802.16 standard. Referring to FIG. 1, the
`rame structure may include a downlink sub-frame (DL sub-
`rame) 16 and an uplink sub—frame (UL sub—,rame) 18. The
`JL sub-frame 18 may follow the DL sub-frame 16 in time
`domain with a transmit/receive transmission gap (TTG) 17
`rom the DL sub-frame 16. Moreover, the frame structure
`may be separated from the next frame structure, led by a
`areamble 10-2, by a receive/transmit transmission gap (RTG)
`19.
`The DI, sub-frame 16 may include a preamble 10-1, a
`rame control header (FCH) 11, a downlink map GDL—MAP)
`12, a downlink burst (DI. burst#1) 13 and a data region
`(DATA) 14-1. The UL sub-frame 18 may include a ranging
`sub-channel 15 and a data region (DATA) 14-2. Since the
`)L-MAI’ 12 may be used to identify the division or structure
`ofthe DATA 14—1 in the DL sub—frame 16, it may be desirable
`o integrate the OFDMA frame structure of an old OFDMA
`system with that of a new OFDMA system by using the
`)L-MAI’ 12 to define different zones in the DATA 14-1 and
`DATA 14—2 ofthe frame structure for data ofthe old OFDMA
`system and data of the new 01"DMA system.
`FIG. 2 is a diagram illustrating a placement of guiding
`signals (or pilot symbols) 24-1 for time-domain and fre-
`quency-domain OFDMA signals under the IEEE 802.16 stan-
`dard. Referring to FIG. 2, upper and lower frequency bands
`may serve as guard bands 22-1 and 22-2, respectively, which
`may not be used to carry intonnation. The placement of
`information may include a first part and a second part. For
`example. the first part of the placement includes a preamble
`10'-1 having a fixed length, and the second part of the place-
`ment includes data and guard intervals between an upper row
`
`
`
`Examples of the present invention may provide a method
`for constructing a frame structure for data transmission, the
`- method comprising generating a first section comprising data
`configured in a first format compatible with a first communi-
`cation system, generating a second section following the first
`section comprising data configured in a second format com-
`patible with a second communication system, wherein the
`’ second format is different from the first format, generating at
`least one non—data section containing infonnation describing
`an aspect of data in at least one of the first section and the
`second section, and combining the first section, the second
`section and the at least one non-data section to form the frame
`structure.
`Examples ofthe present invention may provide a method of
`generating a frame for transferring data in a commumcation
`system. The communication system may include a first sys-
`tem and a second system. The methodmay include generating
`a first sub-frame for downlink transmission, wherein the first
`sub-frame comprises a first region comprising first mapping
`information. a second region comprising second mapping
`information, and a third region carrying data to be transferred
`in the downlink transmission, the third region comprising a
`first sub-region and a second sub-region, wherein the first
`sub-region and second sub-region are defined by the first
`mapping information, the first sub-region being capable of
`carrying first data of the first system and the second sub-
`region being capable of carrying second data of the second
`system in the downlink transmission, and generating a second
`sub-frame for uplink transmission, wherein the second sub-
`frame comprises a fourth region carrying data to be trans-
`ferred in the uplink transmission, the fourth region compris-
`ing a third sub-region and a fourth sub-region, wherein the
`third sub—region and the fourth sub-region are defined by the
`second mapping information,
`the third sub -region being
`capable ofcarrying third data ofthe first system and the fourth
`sub -region being capable ofcarrying fourth data ofthe second
`system in the uplink transmission.
`Examples of the present invention may also provide a
`method of generating a frame for transferring data in a com-
`munication system. The communication system may include
`a first system and a second system. The method may include
`generating a first frame comprising a first sub-frame for
`downlink transmission and a second sub-frame for uplink
`transmission in a first band, generating a second frame com-
`prising a third sub-frame for downlink transmission and a
`fourth sub-frame for uplink transmission in a second hand,
`identifying a guard hand between the first band and the sec-
`ond band, and generating a third frame comprising a fifth
`sub-frame for downlink transmission and a sixth sub-frame
`for uplink transmission in the guard band.
`
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`3
`Examples of the present invention may provide a method
`for allocating information in a frame of a communication
`system. The communication system may include a first sys-
`tem and a second system. The frame may be used for first data
`transmission of the first system and second data transmission
`of the second system. The method may include allocating
`data ofthe first system and the second system in first mapping
`information. dividing a data region ofthe frame to form a first
`sub-region and a second sub-region according to the first
`mapping information. performing the first data transmission
`of the first system by using the first sub -region and perform-
`ing the second data transmission of the second system by
`using the second sub-region.
`Examples of the present invention may provide another
`method for allocating information in a frame ofa communi-
`cation system. The frame may include a first frame, a second
`frame and a hand between the first frame and the second
`frame. The communication system may include a first system
`and a second system. The frame may be used for first data
`transmission ofthe first system and second data transmission
`of the second system. The method may include allocating
`data ofthe first system and the second system in first mapping
`information or second nrapping information, dividing a data
`region of the first frame or the second frame to form a first
`sub-region, a second sub-region, a third sub—region or a sec-
`ond sub-region in the data region of the first frame or the
`second frame according to the first rrrappirrg information or
`he second mapping infomration, performing the first data
`ransmission of the first system by using the first sub—region or
`he third sub-region and performing the second data transmis-
`sion of the second system by using the second sub-region or
`he fourth sub—region.
`Additional features and advantages of the present inven-
`ion will be set forth in part in the description which follows.
`and in part will be obvious from the description, or may be
`earned by practice of the invention. The features and advan-
`ages of the invention will be realized and attained by means
`of the elements and combinations particularly pointed out in
`he appended claims.
`It is to be understood that both the foregoing general
`description and the following detailed description are exem-
`3lary and explanatory only and are not restrictive of the inven-
`tion, as claimed.
`
`
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing summary, as well as the following detailed
`description of the invention, will be better understood when
`read in conjunction with the appended drawings. For the
`purpose of illustrating the invention, there are shown in the
`drawings examples which are presently preferred. It should
`be understood. however. that the invention is not limited to the
`precise arrangements and mstrumentalities shown.
`In the drawings:
`FIG. 1 is a diagram illustrating an orthogonal frequency-
`division multiple access (OFDMA) frame structure under the
`IEEE 802.16 standard;
`FIG. 2 is a diagram illustrating a placement of guiding
`signals for OFDMA signals under the IEEE 802.16 standard;
`FIG. 3 is a diagram illustrating anOFDMA .rame structure
`according to an example of the present invention;
`FIG. 4 is a diagram illustrating anOFDMA .rame structure
`supporting high mobility according to an example of the
`present invention;
`FIG. 5 is a diagram illustrating a110FDMA.rame structure
`with a scalable bandwidth according to an example of the
`present invention;
`
`
`
`30
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`35
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`FIG. 6A is a diagram illustrating an OFDMA frame struc-
`ture supporting high mobility and having a scalable band-
`width according to an example of the present invention;
`FIG. 6B is a diagram illustrating an OFDMA frame struc-
`ture supporting high mobility and having a scalable band-
`width according to another example of the present invention;
`and
`FIG. 7 is a diagram illustrating an exemplary placement of
`signals and pilots in time-domain and frequenc V-domain of
`an OFDMA system supporting high mobility and having a
`scalable bandwidth.
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`DETAILED DESCRIPTION
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`Reference will now be made in detail to various embodi-
`ments of the invention, examples of which are illustrated in
`the accompanying drawings. Wherever possible, the same
`reference numbers will be used throughoth the drawings to
`refer to the same or like parts.
`Examples ofthe present invention may allow data ofan old
`orthogonal frequency—division multiple access (OFDMA)
`system (hereinafter a legacy system) and data of a new
`OFDMA system to co-exist in an OFDMA frame by changing
`’ a frame structure of the OFDMA frame. The new OFDMA
`system may have a larger bandwidth and support higher
`mobility, and may use an updated transmission technology. In
`order to be backward compatible with the old OFDMA sys-
`tem, the new OFDMA system may be developed based on the
`old OFDMA system. Throughout the specification, a “new”
`or “extended” system or standard may refer to an “updated,”
`“evolved” or “next-generation” system or standard, while a
`“legacy” system or standard may refer to an “old” or “cur-
`rent” system or standard. For example, a “new” standard may
`be a standard that is in use as of the date of the filing of this
`application, and a “legacy" standard may be a standard that is
`in use prior to the date ofthe filing ofthis application and may
`be still in use for some time after the filing ofthis application.
`FIG. 3 is a diagram illustrating an OFDMA frame structure
`according to an example ofthe present invention. Referring to
`FIG. 3, the OFDMA frame structure may include a downlink
`sub-frame (DL sub-frame) 16 and an uolink sub-frame (UL
`sub-frame) 18. The DL sub-frame 16 may include a preanrble
`10-1, an FCII 11, a DI.—MAP 12, a DI. burst #1 13 with an
`UP—MAP (not shown), and a data region including DATA
`30-1 (zone 1) and DATA 30-2 (zone 2). The UI. sub-frame 18
`may include a ranging sub-channel 15 and a data region
`including DATA 34—1 (zone 1) and DATA 34-2 (zone 2).
`Data of the new OFDMA system (tie extended system)
`
`may be carried in extended zones, that is, the DATA 30-2
`and/or the DATA 3-1-2, allocated to the DL sub-frame 16
`and/or the UL sub—frarne 18, respectively. Furthermore. the
`extended system in the data region DATA 30-2 and/or the
`DATA 34—2 may have the same symbol period or the same
`’ placement of pilot symbols as the old system (the legacy
`system) in the data region DATA 30-1 and the DATA 34—1.
`respectively, in the OFDMA frame structure. In one example,
`the data region including the two zones DATA 30—1 (zone 1)
`and DATA 30-2 (zone 2), for the old system and the new
`system, respectively, may be placed according to the mapping
`information of the two zones defined in the DI,—MAP 11.
`Similarly, the data region of the UL sub-frame 18 including
`the two zones DATA 34-1 (zone 1) and DATA 34-2 (zone 2),
`for the old OFDMA system and the new OFDMA system,
`respectively. may be placed according to the mapping infor-
`mation of the two zones defined in the UL-MAP in the DL
`burst #1 13.
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`US 8,265,096 B2
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`FIG. 4 is a diagram illustrating an OFDMA frame structure
`suaporting high mobility according to an example of the
`present invention. Referring to FIG. 4, the OFDMA frame
`structure may be similar to that described and illustrated with
`re 'erence to FIG. 3 except that, for example, a DI. sub-frame
`16-2 may further include a preamble 43, a sub-MAP 42-2 and
`a data region DATA 40-3 (zone 3), and a UI, sub-frame 18-2
`may further include a data region DATA 44-3 (zone 3). To
`su aport communication in a high-mobility environment. the
`zones 3 for the new system (the extended system) under high
`mobility may be allocated to the data region of both the DI.
`qu-frame 16-2 and the UL sub-frame 18-2. The DATA 40-3
`and/or 44—3 (zones 3) may have a shorter symbol period or
`more pilot symbols placed therein than the DATA 40-1, 40-2,
`44—1 and 44-2 in order to enhance the performance ofchannel
`es imation. Generally, a shorter symbol period may be more
`ro 3ust to inter-symbol interference, while denser pilot sym-
`bols may achieve better channel estimation accuracy. More-
`over, the DATA 40—3 of the DL sub-frame 16—2 for the new
`system (extended system) under high mobility may be
`divided based on the mapping information defined in at least
`one ofthe DL-MAP 11 and the sub—MAP 42-2 ofDATA 40—3,
`and the DATA 44-3 of the UL sub-frame 13-2 for the new
`system (extended system) under high mobility may be
`divided based on the mapping information defined in the
`JL—MAP (not shown) in the DL burstii‘l 13. Placements of
`oilot symbols, symbol periods of OFDM symbols and Fl—"l'
`sizes in the zones 1 for the old (legacy) system and the zones
`2 for the new (extended) system may be the same in the DL
`sub-frame 16—2 and the UL sub—frame 18—2. The preamble 43
`alaced in front ofthe zone 3 of the DL sub-frame 16-2 for the
`new system (extended system) may be used to support high
`mobility. As compared to the zones in the data region of the
`JL sub-frame 18-2 or the DL sub-frame 16-2 of the old/
`egacy system or the new/extended system, the placements of
`he pilot symbols may be denser, the symbol periods of
`OFDM symbols may be shorter and the FFT sizes may be
`smaller in the DATA 40-3 and/or DATA 44-3 of the DL
`sub-frame 16—2 or the UL sub—frame 18-2, respectively, for
`he extended system under high mobility.
`FIG. 5 is a diagram illustrating an OFDMA frame structure
`with a scalable bandwidth according to an example of the
`aresent invention. Referring to FIG. 5, the OFDMA frame
`structure may include a first frame structure 500, a second
`rame structure 502 and a third frame structure 504. The first
`'rame structure 500 may include a first DI, sub-frame 16-351
`and a first UL sub—frame 18—30, the second frame structure
`502 may include a second DI, sub-frame 16—317 and a second
`JL sub-frame 18-319, and the third frame structure 504 may
`include a third DL sub—frame 16-30 and a third UL sub—frame
`18-3c. The first frame structure 500, which may be allocated
`o a first band. may be similarto the frame structure described
`and illustrated with reference to FlG. 3. Specifically, the first
`3L sub-frame 16-30 of the first frame structure 500 may
`include a preamble 50-1, an FCl—l, a DL-MAl’ 54-1, a DL
`urst #1 55—1 with an UL MAP (not shown), DATA 56-1
`(zone 1) for the old OFDMA system (legacy system) and
`DATA 56—30 (zone 2) for the new OFDMA system (extended
`system). The first UL sub-frame 18-351 of the first frame
`structure 500 may include a ranging sub-channel 58-1, DATA
`59-2 (zone 1) in the data region for the old OFDMA system
`(legacy system) and DATA 59-1a (zone 2) in the data region
`for the new OFDMA system (extended system).
`The second frame structure 502, which may be allocated to
`a second band, may be similar to the frame structure
`described and illustrated with reference to FIG. 3. Similarly,
`the second DL sub—frame 1 6-3b ofthe second frame structure
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`502 may include a preamble 52-1, an FCIl, a DL-MAP 54-2,
`a DL burst #1 55—2 with an UL MAP (not shown), DATA 56-2
`(zone 1) in a data region for the old OFDMA system (legacy
`system) and DATA 56-319 (zone 2) in the data region for the
`new OFDMA system (extended system), and the second UI.
`sub-frame 18-3b of the second frame structure 502 may
`include a ranging sub-channel 58-2, DATA 59-3 (zone 1) in a
`data region for the old OFDMA system (legacy system) and
`7ATA 59-4 (zone 2) in the data region for the new OFDMA
`system (extended system).
`The third frame structure 504, which maybe allocated to a
`hird band, may be arranged between the first frame structure
`500 and the second frame structure 502. Specifically, a guard
`aand between the first frame structure 500 and the second
`,rame structure 502 may serve as the third frame structure 504
`o facilitate data transmission. Unlike the guard band 22-1 or
`22—2 in FIG. 2, data to be transmitted in the new (extended)
`system or a high-mobility system maybe allocated to a guard
`3and between the first frame structure 500 and the second
`rame structure 502. The third frame structure 504 may
`include a third DL sub-frame 16-30 and a third UL sub-frame
`18—30. The DL sub—frame 16—313 may include a preamble 51—1,
`an FCH, a DL-MAP and a data region DATA 56-3c (zone 3)
`or the new (extended) system. Furthermore, the UL sub-
`,rame 18-30 may include a data region DATA 59-117 for the
`new (extended) system.
`An OFDMA frame structure thus constructed may have a
`scalable bandwidth. For example, data of the old (legacy)
`OFDMA system in the zones 1 ofthe first frame structure 500
`and the second frame structure 502 may be transmitted in
`parallel using the first band and second band, respectively,
`and data of the new (extended) OFDMA system in the third
`frame structure 504 and the zones 2 ofthe first frame structure
`500 and the second frame structure 502 may be together
`transmitted using the first, second and third bands. In one
`example, the first, second and third bands may be contiguous
`with one another. Furthermore, upper and a lower guard
`3ands (not shown) may be required to transmit the OFDMA
`,rame structure via the first, second and third bands.
`The “zone 1" 56-1 of the first frame structure 500 and the
`‘zone 1” 56—2 of the second frame structure 502 may be
`divided from the data region in the DL sub-frame 1 6-3a ofthe
`1rst frame structure 500 and the data region in the DL sub-
`rame 16-3}; of the second frame structure 502, respectively,
`according to the mapping information in the DL-MAP 54-1
`and the DI ,-MAP 54-2, respectively. Similarly, the UI , sub-
`,rame 18-311 of the first frame structure 500 and the UL
`sub-frame 18—3)) of the second frame structure 502 may be
`divided based on the mapping information in the UL—MAP in
`he DL burst #1 55-1 of the first frame structure 500 and the
`JL-MAP in the DL burst#1 55-2 of the second frame struc-
`ure 502, respectively.
`The guard band 504, which is in a frequency spectrum not
`used in the old or legacy system. may be used to transfer data
`in the present example, and the data region of the guard band
`may be divided based on the mapping information in at least
`one ofthe DL-MAP 54-1 or the DL-MAP 54-2. The preamble
`part of the extended frame structure described and illustrated
`with reference to FIG. 5 may include the preamble 50-1 and
`the preamble 52-1. The preamble 51-1 may carry data, or may
`carry no information. Moreover, the DI .-MAP and the FCII in
`the guard band 504 may be used to divide the data regions
`56-3r and 59-1 17. In one example, a Sub-MAP (not shown)
`may be placed in the DATA 56-30 for further description of
`the extended system.
`FIG. 6A is a diagram illustrating an example of an
`OFDMA frame structure supporting high mobility and hav-
`
`‘
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`ity may be the same or denser than the that in the prior art, and
`the placement of the pilot symbols in a third region such as
`one of the regions 74-4 and 76-4 of the frame structure
`divided for the new OFDMA system supportng high mobil-
`ity may use more denser pilot placement with more pilot
`symbols for increasing accuracy of the charmel estimation.
`It will be appreciated by those skilled in the art that changes
`could be made to the examples described above without
`departing from the broad inventive concept thereof. It is
`understood, therefore, that this invention is not limited to the
`aarticular examples disclosed. but it is intended to cover
`modifications within the spirit and scope ofthe present inven-
`ion as defined by the appended claims.
`Further,
`in describing representative examples of the
`' aresent invention, the specification may have presented a
`method and]or process ofthe present invention as a particular
`sequence of steps. However, to the extent that the method or
`orocess does not rely on the particular order of steps set forth
`ierein, the method or process should not be limited to the
`oarticular sequence of steps described. As one of ordinary
`skill in the art would appreciate, other sequences of steps may
`2e possible. Therefore, the particular order of the steps set
`orth in the specification should not be construed as limita-
`ions on the claims, In addition, the claims directed to the
`’ method and/or process of the present invention should not be
`imited to the performance of their steps in the order written.
`and one skilled in the art can readily appreciate that the
`sequences may be varied and still remain within the spirit and
`scope of the present invention.
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`ing a scalable bandwidth according to an example of the
`present invention. Referring to FIG. 6A, the frame structure
`may be similar to the frame structure in FIG. 5 except that, for
`example, regions related to zones 3 for a high-mobility envi-
`ronment may be added. Specifically, in a DI. sub-frame 16-4,
`a firstrcgion may include apreainble 68, a sub-MAP 67-2 and
`DATA 66-4, and in a UI, sub-frame 18-4, a second region may
`include DATA 69-3 and 69-6 (zones 3). DATA 66-4, 69-3 and
`69—6 maybe allocated for the new OFDMA system (extended
`system) under high mobility. The DL sub-frame 16-4 may be
`divided according to the mapping information in DL—MAP 1.
`DL-MAP 2 and DL-MAI’ 3, while the UL sub-frame 18-4
`may be divided according to the map information in UL-
`MAl’s in DL burst#1 65-1 and/or 65-2. A portion ofthe guard
`band that overlaps data zones 69-1 and 69—2 in the UL sub-
`frame 18-4 may be used to transmit data in the extended
`system. In one example, placements ofpilot symbols, symbol
`periods of OFDM symbols and FFT sizes in the zones 1 for
`the old (legacy) system and the zones 2 for the new (extended)
`system may be the same in the DI. sub-frame 16—4 and the UI.
`sub-frame 18-4. As compared to the zones in the data region
`of the DL sub—frame 16—4 or the UL sub-frame 18—4 of the
`old/legacy system or the new/extended system, the place-
`ments ofthe pilot symbols may be denser. the symbol periods
`of OFDM symbols may be shorter and the Fl—"f sizes may be
`smaller in the zones 3 of the UL sub—frame 18—4 or the DL
`sub-frame 16-4 for the extended system under high mobility.
`FIG. 6B is a diagram illustrating an OFDMA frame struc-
`ture supporting high mobility and having a scalable band-
`width according to another example of the present invention.
`Referring to FIG. 6B, the OFDMA frame structure may be
`similar to the OFDMA frame structure described or illus-
`trated with reference to FIG. 6A except that, for example, the
`zone 2 in a UL sub-frame 13-4' using the guard band may be
`transmitted after the 7one 3 in the UI . sub-frame 18-4‘, and the
`locations of zones 1 for the legacy system and zones 3 for the
`new (extended) system for high mobility are swapped.
`FIG. 7 is a diagram illustrating an exemplary pla