(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/014.6867 A1
`Lee et al.
`(43) Pub. Date:
`Jul. 6, 2006
`
`US 2006O146867A1
`
`(54) APPARATUS AND METHOD FOR SIGNAL
`CONSTITUTION FOR DOWNLINK OF
`OFDMA-BASED CELLULAR SYSTEM
`
`(76) Inventors: Lok-kyu Lee, Daejeon (KR):
`Kwang-Soon Kim, Daejeon (KR):
`Kyung-Hi Chang, Daejeon (KR)
`Correspondence Address:
`BLAKELY SOKOLOFFTAYLOR &
`ZAFMANAPDC
`124OO WILSHIRE BOULEVARD
`SEVENTH FLOOR
`LOS ANGELES, CA 90025 (US)
`
`(21) Appl. No.:
`(22) PCT Filed:
`
`10/539,166
`Jun. 2, 2003
`
`PCT/KRO3AO1083
`(86). PCT No.:
`(30)
`Foreign Application Priority Data
`
`Dec. 13, 2002 (KR)............................ 10-2002-OO79.598
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`H04O 7/20
`(2006.01)
`HO4, 3/6
`(2006.01)
`H04 3/22
`(2006.01)
`H04 II/00
`(52) U.S. Cl. ....................... 370/465; 370/208; 455/452.1
`
`ABSTRACT
`(57)
`Disclosed are an adaptive pilot symbol assignment method
`that flexibly controls the number of transmit antennas
`according to each user's moving speed, channel status, or
`user request, and assigns proper pilot symbols in the down
`link of an OFDMA (Orthogonal Frequency Division Mul
`tiplexing Access) based cellular system; and a sub-carrier
`allocation method for high-speed mobile that allocates some
`Sub-carriers to assign proper pilot symbols for ultrahigh
`speed mobile users, and the rest of the sub-carriers to the
`other users to assign proper pilot symbols to the users, on the
`assumption that the ultrahigh-speed mobile users have a
`traffic volume almost insignificant to the whole traffic vol
`le.
`
`Common/
`Control Channel data
`
`Traffic channel data
`
`
`
`
`
`Assign symbols for common/
`COntrol channels
`
`S100
`
`Traffic channel
`Symbol
`
`
`
`
`
`Additional
`pilot symbol
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 1 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 1 of 9
`Fig. 1
`
`US 2006/014.6867 A1
`
`
`
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`
`
`
`NOENLLIN
`<!--|-|-|-|-|-|-|-
`No..
`
`Fig. 2
`
`| || || || || || || || ||
`
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`ZZ Z
`2 pilot symbol
`data Symbol
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 2 of 17
`
`

`

`% %
`
`2%
`%
`
`
`
`% %
`
`2 2
`
`
`
`H 2 2
`
`Patent Application Publication Jul. 6, 2006 Sheet 2 of 9
`Fig. 3
`
`US 2006/014.6867 A1
`
`
`
`
`
`2%
`
`
`
`2. Md
`2
`
`
`
`
`
`2 2 23.
`
`2 2
`
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`
`% 5% 1.
`data Symbol % pilot Symbol
`
`Fig. 4
`
`Common/
`COntrol channel data
`mus-a-se
`
`
`
`Traffic channel data Assign symbols for traffic channel NS200
`
`
`
`Traffic channel
`Symbo
`
`Additional
`pilot Symbol
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 3 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 3 of 9
`Fig. 5
`
`
`
`US 2006/014.6867 A1
`
`Traffic
`channel data
`
`Transmission
`mOde
`
`Perform Coding,
`inter leaving, and
`Symbol-mapping
`aCCOrding to
`transmission mode
`
`store traffic channel data
`
`Determine transmission mode
`and number of additional
`antennaS
`
`Channel Status
`Traffic requirement
`Moving Speed
`
`Assign pilot Symbols for
`additional antenna
`
`Assign additional pilot
`Symbols for basic/
`additional antennas
`
`Moving Speed
`S240
`
`Traffic channel symbol
`
`Additional pilot Symbol
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 4 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 4 of 9
`
`US 2006/014.6867 A1
`
`
`
`Z
`
`A
`
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`o
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`
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`o EA 2
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`
`COMMOm &
`2 Control
`channeles
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 5 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 5 of 9
`Fig. 7
`
`US 2006/014.6867 A1
`
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`
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`
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`channeles
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 6 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 6 of 9
`Fig. 8
`
`US 2006/014.6867 A1
`
`
`
`
`
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`Six so o oso a Nixo lo & Loo ol
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`o EA 2
`Antenna
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 7 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 7 of 9
`Fig. 9
`Zooloo oooooooooooo
`
`US 2006/014.6867 A1
`
`2EEEEEEEEEEE
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`
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`
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`Using 2
`Antenna
`
`User 4 Data
`o High Speed
`Using 2
`Antenna
`
`CommOm &
`2 Control
`channeles
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 8 of 17
`
`

`

`Patent Application Publication
`
`Jul. 6, 2006 Sheet 8 of 9
`
`US 2006/0146867 A1
`U007
`
`?007003
`
`(2009
`
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`
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`
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`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 9 of 17
`
`

`

`Patent Application Publication Jul. 6, 2006 Sheet 9 of 9
`Fig.11
`
`US 2006/014.6867 A1
`
`Channel Traffic
`status requirement
`
`
`
`Perform coding, inter leaving,
`and Symbol-mapping acCOrding
`to transmission mode,
`and a locate Sub-Carrier
`
`
`
`
`
`
`
`Sub-Carrier
`
`
`
`
`
`S410
`Channel Traffic
`status requirement
`
`Perform Coding, inter leaving,
`and Symbol-mapping acCOrding
`to transmission mode, and
`all OCate Sub-Carrier
`
`For High Speed
`Mobile user
`
`For Middle/LOW/
`Fixed Speed
`Mobile user
`
`Symbol
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 10 of 17
`
`

`

`US 2006/014.6867 A1
`
`Jul. 6, 2006
`
`APPARATUS AND METHOD FOR SIGNAL
`CONSTITUTION FOR DOWNLINK OF
`OFDMA-BASED CELLULAR SYSTEM
`
`BACKGROUND OF THE INVENTION
`0001) (a) Field of the Invention
`0002 The present invention relates to an apparatus and
`method for signal constitution for a downlink of an OFDMA
`(Orthogonal Frequency Division Multiplexing Access)
`based cellular system. More specifically, the present inven
`tion relates to an apparatus and method for adaptive pilot
`symbol assignment and Sub-carrier allocation that reduces
`transmission power consumption and overhead caused by
`pilot symbols and increases the total data rate on the
`downlink of an OFDMA-based cellular system.
`0003) (b) Description of the Related Art
`0004. In the design of pilot assignment, it is necessary to
`use a sufficiently large number of pilot symbols for the sake
`of preventing a deterioration of reception performance
`caused by a channel variation, and to prevent an excessive
`increase of a power loss or a bandwidth loss caused by pilot
`symbols above an expected value. The positioning (assign
`ment) of pilot symbols is of a great significance to the
`receiver of an OFDMA-based system, which estimates a
`transfer function value of channels in a two-dimensional
`(time, frequency) space. Hence, both the time domain and
`the frequency domain must be taken into consideration in
`pilot symbol assignment so as to transmit the pilot symbols.
`In case of using a plurality of antennas, the pilot symbols of
`the multiple antennas are assigned in consideration of both
`the time domain and the frequency domain.
`0005 The distance between pilot symbols must be quite
`Small in designing pilot symbols in the worst environment,
`or when using non-optimal channel estimation filters having
`a lower complexity.
`0006 Let f be a sub-carrier bandwidth, then the maxi
`mum pilot distance N in the frequency domain based on the
`conventional sampling theory (F. Classen, M. Speth, and H.
`Meyr, “Channel estimation units for an OFDM system
`suitable for mobile communication', in ITG Conference on
`Mobile Radio, Neu-Ulm, Germany, September 1995) is
`determined by the following formula:
`0007
`Formula 1
`
`is the maximum exceedance delay time of a
`where T,
`channel. The maximum pilot distance NT in the frequency
`domain is determined by the following formula:
`0008
`Formula 2)
`
`NT s 2fpT.
`
`where f is the maximum Doppler frequency; and Ts is the
`symbol time.
`0009. The symbol time Ts, during which the maximum
`pilot distance is proportional to the coherent time, is nor
`malized by the number of symbols. So, the maximum pilot
`distance in the time domain is proportional to the coherent
`bandwidth and normalized by the sub-carrier bandwidth.
`0010) The balanced design (P. Hoeher et al., “Pilot
`symbol-aided channel estimation in time and frequency.
`Multi-carrier Spread-Spectrum, accepted for publication in
`Kluwer Academic Publishers, 1997) defines that the estima
`tion uncertainty in the time domain is equal to that in the
`frequency domain. Here, P. Hoeher et al. Suggest a design
`guide having two-fold oversampling as defined by a heu
`ristic formula as follows:
`Formula 3
`2fTsNT staf'NFs'/2
`where N is the pilot distance in the frequency domain. The
`above-mentioned pilot symbol assignment is primarily a
`rectangular pilot symbol assignment, which is illustrated in
`FIG. 1. FIGS. 2 and 3 show a straight pilot symbol
`assignment and a hexagonal pilot symbol assignment,
`respectively. Generally, the hexagonal pilot symbol assign
`ment allows more efficient sampling, compared with two
`dimensional signals, and exhibits excellent performance
`relative to other assignments. An example of the pilot
`symbol assignment is disclosed in “Efficient pilot patterns
`for channel estimation in OFDM systems over HF channels'
`(M. J. Fernandez-Getino Garcia et al., in Proc IEEE
`VTC1999).
`0011. As the pilot symbol assignment becomes denser,
`the channel estimation performance becomes more excellent
`but the data rate is decreased. Hence, a trade-offlies between
`the data rate and the channel estimation performance (i.e.,
`pilot symbol distance).
`0012. There exits a pilot symbol distance that optimizes
`the trade-off between the improved channel estimation and
`the signal-to-noise ratio (SNR) reduced by data symbols. By
`varying the pilot symbol distances NE and N the values
`approximate to the optimum with reference to the perfor
`mance of bit error rate (BER) can be determined. In FIG. 1,
`for example, N=4 and NT=3 in optimum means that one
`twelfth (about 8%) of the consumed transmission power and
`bandwidth are used for pilot symbols.
`0013 In this optimal assignment of pilot symbols, the
`channel environment and the moving speed of the mobile
`users are of a great importance as parameters to be consid
`ered.
`
`SUMMARY OF THE INVENTION
`0014. It is an advantage of the present invention to
`provide an apparatus and method for adaptive pilot symbol
`assignment and Sub-carrier allocation that reduces transmis
`sion power and overhead caused by pilot symbols and
`increases the total data rate on a downlink in an OFDMA
`based cellular system.
`0015. In one aspect of the present invention, there is
`provided a downlink signal constitution method, which is
`for a downlink of a cellular system using an orthogonal
`frequency division multiplexing access method, the down
`link signal constitution method including: (a) coding, inter
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 11 of 17
`
`

`

`US 2006/014.6867 A1
`
`Jul. 6, 2006
`
`leaving, and symbol-mapping data of a common channel
`and a control channel, and assigning fundamental pilot
`symbols, necessary for a demodulation of the common
`channel and the control channel, to time, frequency, and
`antenna; (b) receiving data to be transmitted through a traffic
`channel of each user, and determining a transmission mode
`of each user according to the user's moving speed, channel
`information, and traffic requirement; (c) determining addi
`tional pilot symbols, additionally necessary for a demodu
`lation of the traffic channel, according to the transmission
`mode and moving speed by users; and (d) coding, interleav
`ing and symbol-mapping the data of the traffic channel
`according to the transmission mode by users, and assigning
`the mapped symbols and the additional pilot symbols
`according to time, frequency and antenna.
`0016.
`In another aspect of the present invention, there is
`provided a downlink signal constitution method, which is
`for a cellular system using an orthogonal frequency division
`multiplexing access method, the downlink signal constitu
`tion method including: (a) dividing users into a first user
`group including high-speed mobile users and a second user
`group including the rest of the users, in consideration of each
`user's moving speed and traffic volume; (b) allocating a first
`Sub-carrier band for the first user group, and a second
`Sub-carrier band for the second user group; and (c) assigning
`pilot symbols to the first and second sub-carrier bands, the
`pilot symbols assigned to the first Sub-carrier band being
`different in assignment density from the pilot symbols
`assigned to the second sub-carrier.
`0017. In a further aspect of the present invention, there is
`provided a downlink signal constitution apparatus, which is
`for a cellular system using an orthogonal frequency division
`multiplexing access method, the downlink signal constitu
`tion apparatus including: a first memory for storing traffic
`channel information of each user; a second memory for
`storing channel information, traffic requirement, and moving
`speed information of each user; a transmission user and
`transmission mode determiner for determining a transmis
`sion user and a transmission mode according to a defined
`method using the information stored in the second memory;
`a traffic channel processor for reading the traffic channel
`information stored in the first memory according to the
`transmission mode determined by the transmission user and
`transmission mode determiner, and performing coding,
`interleaving, and symbol-mapping of the traffic channel; an
`additional pilot symbol generator for generating additional
`pilot symbols necessary for a demodulation of the traffic
`channel, using the transmission mode determined by the
`transmission user and transmission mode determiner and the
`moving speed information stored in the second memory; and
`a time/sub-carrier/antenna mapper for multiplying the traffic
`channel symbols output from the traffic channel processor
`and the additional pilot symbols output from the additional
`pilot symbol generator by a channel gain by channels/users,
`and mapping the resulting symbols to time, Sub-carrier, and
`antenna by a defined method.
`0018. In a still further aspect of the present invention,
`there is provided a recording medium with a built-in pro
`gram, which implements a downlink signal constitution
`method for a cellular system using an orthogonal frequency
`division multiplexing access method, the program including:
`a function of coding, interleaving, and symbol-mapping data
`of a common channel and a control channel, and assigning
`
`fundamental pilot symbols, necessary for a demodulation of
`the common channel and the control channel, to time,
`frequency, and antenna; a function of receiving data to be
`transmitted through a traffic channel of each user, and
`determining a transmission mode of each user according to
`the user's moving speed, channel information, and traffic
`requirement; a function of determining additional pilot sym
`bols, additionally necessary for a demodulation of the traffic
`channel, according to the transmission mode and moving
`speed by users; and a function of coding, interleaving and
`symbol-mapping the data of the traffic channel according to
`the transmission mode by users, and assigning the mapped
`symbols and the additional pilot symbols according to time,
`frequency, and antenna.
`0019. In a still further aspect of the present invention,
`there is provided a recording medium with a built-in pro
`gram, which implements a downlink signal constitution
`method for a cellular system using an orthogonal frequency
`division multiplexing access method, the program including:
`a function of dividing users into a first user group including
`high-speed mobile users and a second user group including
`the rest of the users, in consideration of each user's moving
`speed and traffic Volume; a function of allocating a first
`Sub-carrier band for the first user group, and a second
`Sub-carrier band for the second user group; and a function of
`assigning pilot symbols to the first and second Sub-carrier
`bands, the pilot symbols assigned to the first Sub-carrier
`band being different in assignment density from the pilot
`symbols assigned to the second sub-carrier.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0020. The accompanying drawings, which are incorpo
`rated in and constitute a part of the specification, illustrate an
`embodiment of the invention, and, together with the descrip
`tion, serve to explain the principles of the invention:
`0021
`FIG. 1 is an exemplary diagram of a rectangular
`pilot symbol assignment;
`0022 FIG. 2 is an exemplary diagram of a straight pilot
`symbol assignment;
`0023 FIG. 3 is an exemplary diagram of a hexagonal
`pilot symbol assignment;
`0024 FIG. 4 is a flow chart showing a symbol assign
`ment method for a downlink of an OFDMA-based cellular
`system according to an embodiment of the present inven
`tion;
`0025 FIG. 5 is a detailed diagram showing a symbol
`assignment method for the traffic channel of FIG. 4;
`0026 FIG. 6 is a diagram showing a downlink signal
`constitution method according to the embodiment of the
`present invention;
`0027 FIG. 7 is an exemplary diagram of a pilot symbol
`assignment for low-speed mobile users using four antennas;
`0028 FIG. 8 is an exemplary diagram of a pilot symbol
`assignment for high-speed mobile users using two antennas;
`0029 FIG. 9 is an exemplary diagram showing a down
`link signal constitution method when using additional anten
`nas only in a part of the whole band in an FDD system;
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 12 of 17
`
`

`

`US 2006/014.6867 A1
`
`Jul. 6, 2006
`
`0030 FIG. 10 is a diagram of a downlink signal consti
`tution apparatus for an OFDMA-based cellular system
`according to the embodiment of the present invention;
`0031
`FIG. 11 is a detailed flow chart showing a pilot
`symbol assignment according to Sub-carrier allocation; and
`0032 FIG. 12 is an exemplary diagram showing a pilot
`symbol assignment according to a sub-carrier allocation for
`high-speed mobile users and a moving speed.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0033. In the following detailed description, only the
`preferred embodiment of the invention has been shown and
`described, simply by way of illustration of the best mode
`contemplated by the inventor(s) of carrying out the inven
`tion. As will be realized, the invention is capable of modi
`fication in various obvious respects, all without departing
`from the invention. Accordingly, the drawings and descrip
`tion are to be regarded as illustrative in nature, and not
`restrictive.
`0034 FIG. 4 is a diagram showing a downlink symbol
`assignment method for an OFDMA-based cellular system
`according to an embodiment of the present invention.
`0035. The symbol assignment method according to the
`embodiment of the present invention comprises, as shown in
`FIG. 4, a symbol assignment step S100 for common/control
`channels, a symbol assignment step S200 for traffic chan
`nels, and a traffic channel signal constitution step S300.
`0.036 More specifically, the symbol assignment step
`S100 for common/control channels performs coding, inter
`leaving, and symbol mapping on data of common and
`control channels, and assigns the mapped symbols to time,
`frequency, and antennas. Also, fundamental pilot symbols
`necessary for demodulation of the common and control
`channels are assigned to time, frequency, and antennas.
`0037. The symbol assignment step S200 for traffic chan
`nels receives data to be transferred through the traffic
`channel of each user; determines each user's transmission
`mode according to the user's moving speed, channel infor
`mation, and traffic requirement; performs coding, interleav
`ing, and symbol-mapping according to the transmission
`mode of the user, and assigns the traffic channel symbols of
`each user to time, frequency, and antennas. Also, pilot
`symbols additionally necessary for a demodulation of the
`traffic channel are generated according to the transmission
`mode by users, and assigned to time, frequency, and anten
`aS.
`0038. The traffic channel signal constitution step S300
`constitutes the signal of the traffic channel using the traffic
`channel symbols of each user and the additional pilot
`symbols output from the step S200.
`0.039
`FIG. 5 is a detailed diagram of the symbol assign
`ment S200 for traffic channels shown in FIG. 4.
`0040. When the base station has information about the
`moving speed and channel status of each user, a required
`number of pilot symbols are inserted, reducing transmission
`power and overhead caused by pilot symbols.
`0041 According to the embodiment of the present inven
`tion, the transmitter antennas are divided into basic antennas
`
`and additional antennas. The basic antenna refers to an
`antenna used for transmitting common and control channels,
`while the additional antenna refers to an antenna addition
`ally used to enhance the transmission rate or performance of
`the traffic channel of the user.
`0042. In the OFDMA system, one frequency band is
`divided into a plurality of sub-carrier bands to transmit the
`traffic channel of each user through the allocated sub
`carriers. Namely, the OFDMA system properly allocates a
`Sub-carrier band according to the user's moving speed,
`channel environment, and traffic requirement, or selects a
`defined sub-carrier band, determines the number of trans
`mitter antennas according to the user's moving speed, chan
`nel environment, and traffic requirement, and then assigns
`additionally necessary pilot symbols to the allocated sub
`carrier band.
`0.043 More specifically, as illustrated in FIG. 5, the
`OFDMA system stores data to be transmitted through a
`traffic channel, in step S210.
`0044) The transmission mode and the number of addi
`tional antennas are determined in consideration of the user's
`channel information (i.e., channel status), traffic require
`ment, and moving speed, in Step S220.
`0045. In step S230, the system assigns pilot symbols for
`additional antennas, when the additional antennas are
`needed according to the transmission mode determined in
`the step S220.
`0046) The additional pilot symbols according to the mov
`ing speed of the basic antennas and the additional antennas
`are then assigned in consideration of the user's moving
`speed, in step S240.
`0047 The system performs coding, interleaving, and
`symbol mapping using the transmission mode determined in
`the step S220 and the traffic channel data stored in the step
`S210 to generate coded, interleaved, and symbol-mapped
`traffic channel symbols, in step S250.
`0048. In the step S220, the transmission mode for each
`user is determined independently, or the transmission mode
`for multiple users is determined by optimization in consid
`eration of the total transmission rate, the quality of service,
`or the total transmission power.
`0049 FIG. 6 is an exemplary diagram showing a down
`link signal constitution method according to the embodi
`ment of the present invention.
`0050. In FIG. 6, when using one basic antenna and at
`most three additional antennas, the pilot symbols are
`assigned to the Sub-carrier band, which is allocated to a user
`1 moving at high speed with one basic antenna, a user 2
`moving at low speed with one additional antenna, a user 3
`moving at low speed with three additional antennas, and a
`user 4 moving at high speed with one additional antenna.
`0051. In FIG. 6, seventeen OFDM symbols constitute
`one slot. FIG. 6 shows the case where a demodulation can
`be enabled with one pilot symbol in one slot in the time
`domain because the moving speed is low.
`0052 Referring to FIG. 6, the common and control
`channels are used to transmit OFDM symbols such as pilot
`symbols of the basic antenna, and demodulate them irre
`spective of the moving speed of the users. The traffic channel
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 13 of 17
`
`

`

`US 2006/014.6867 A1
`
`Jul. 6, 2006
`
`is used to transmit the additional pilot symbols necessary
`according to the moving speed of the users and the number
`of antennas in the allocated Sub-carrier band by users.
`0053 FIG. 7 is an exemplary diagram showing a pilot
`symbol assignment in the Sub-carrier band allocated to a
`low-speed mobile user using one basic antenna and three
`additional antennas according to the embodiment of the
`present invention.
`0054 The pilot symbols (N=5) of the basic antenna
`(antenna 0) and the common and control channels are
`transmitted for the first OFDMA symbol, and the traffic
`channel is transmitted for the other OFDMA symbols. The
`pilot symbols of the additional antennas (antenna 1, antenna
`2, antenna 3) are additionally transmitted. In the meantime,
`the symbols of the traffic channel can be generated by any
`one of the following methods: (1) a first method of gener
`ating traffic channel symbols previously in consideration of
`the number of additional pilots; (2) a second method of
`generating the maximum number of traffic channel symbols
`and then puncturing at positions to transmit additional pilot
`symbols; and (3) a third method of generating traffic channel
`symbols previously in consideration of the number of a part
`of additional pilot symbols, and then puncturing at positions
`to transmit the rest of the additional pilot symbols.
`0.055
`FIG. 8 is an exemplary diagram showing a pilot
`symbol assignment in the Sub-carrier band allocated to a
`high-speed mobile user using one basic antenna and one
`additional antenna according to the embodiment of the
`present invention.
`0056. The pilot symbols (N=5) of the basic antenna
`(antenna 0) and the common and control channels are
`transmitted for the first OFDMA symbol, and the traffic
`channel is transmitted for the other OFDMA symbols. The
`pilot symbols of the additional antenna (antenna 1) are
`additionally transmitted.
`0057. In the meantime, the symbols of the traffic channel
`can be generated by one of the following methods: (1) a first
`method of generating traffic channel symbols previously in
`consideration of the number of additional pilots; (2) a
`second method of generating the maximum number of traffic
`channel symbols and then puncturing at positions to transmit
`additional pilot symbols; and (3) a third method of gener
`ating traffic channel symbols previously in consideration of
`the number of a part of additional pilot symbols, and then
`puncturing at positions to transmit the rest of the additional
`pilot symbols.
`0.058. In summary, there are four cases of pilot symbol
`assignment in relation to the number of antennas of the
`traffic channel:
`0059 (1) moving at a low speed with one basic
`antenna—using no additional pilot symbol;
`0060 (2) moving at low speed with additional anten
`nas—assigning pilot symbols for additional antennas;
`0061 (3) moving at high speed with one basic antenna—
`additionally inserting pilot symbols for basic antenna in
`conformity to the high-speed environment; and
`0062 (4) moving at high speed with additional anten
`nas—additionally inserting pilot symbols for basic and
`additional antennas in consideration of the moving speed.
`
`0063) To use the methods illustrated in FIGS. 4 to 8, the
`base station must have information about the channel infor
`mation, moving speed, and traffic requirement of each user.
`The moving speed is measured at the base station, or is
`measured at the mobile station and then reported to the base
`station. The traffic requirement is reported to the base station
`by the mobile station, or is detected by the base station from
`the amount or characteristic of data to be transmitted. The
`channel information is measured at the base station, or is
`measured at the mobile station and then reported to the base
`station. The former case is primarily for the TDD (Time
`Division Duplex) based system, and the latter one is for the
`FDD (Frequency Division Duplex) based system.
`0064. In the former case, the mobile station sends a signal
`(e.g., preamble, pilot, etc.) for channel measurement, and
`then the base station measures the channel information of
`the uplink by the respective antennas based on the received
`signal. The base station acquires channel information of the
`downlink using the reciprocity of channels because the
`uplink and the downlink have the same channel information
`because they use the same frequency band.
`0065 Contrarily, in the FDD system, the mobile station
`previously sends pilots of additional antennas So as to
`perform a channel estimation of the additional antennas.
`0066 FIG. 9 is an exemplary diagram showing a down
`link signal constitution method when using additional anten
`nas only in a defined band in the FDD system.
`0067 Namely, FIG. 9 shows the addition of an appro
`priate quantity of pilot symbols for additional antennas to
`the first symbol only in a defined band so as to reduce
`overhead caused by transmitting pilots of additional anten
`aS.
`0068. In FIG. 9, one basic antenna (antenna 1) is used,
`and the third band is a band available for using at most three
`additional antennas, the fourth band being a band available
`for using at most one additional antenna, the other bands not
`being available for using additional antennas.
`0069 FIG. 10 is a diagram of a downlink signal consti
`tution apparatus 100 for an OFDMA-based cellular system
`according to the embodiment of the present invention.
`0070 The downlink signal constitution apparatus 100
`comprises a common/control channel processor 110, a fun
`damental pilot symbol generator 120, a traffic channel
`information memory 130, a traffic channel processor 140, a
`channel information/traffic requirement/moving speed
`memory 150, a transmission user and transmission mode
`determiner 160, an additional pilot symbol generator 170,
`and a time/sub-carrier/antenna mapper 180.
`0071. The common/control channel processor 110
`encodes and interleaves the common/control channel infor
`mation, and maps the coded and interleaved common/
`control channel information to symbols to generate a coded/
`interleaved/symbol-mapped
`common/control
`channel
`symbol. The fundamental pilot symbol generator 120 gen
`erates a fundamental pilot symbol. The fundamental pilot
`symbol is a pilot symbol transmitted irrespective of the
`transmission mode of the traffic channel of the user, and in
`FIGS. 6 and 9, refers to a pilot symbol transmitted for the
`first OFDM symbol of the slot.
`
`Exhibit 1013
`Panasonic v. UNM
`IPR2024-00364
`Page 14 of 17
`
`

`

`US 2006/014.6867 A1
`
`Jul. 6, 2006
`
`0072 The traffic channel information memory 130 stores
`the user's traffic channel information, and the channel infor
`mation/traffic requirement/moving speed memory 150 stores
`the user's channel information, traffic requirement, and
`moving speed information.
`0073. The transmission user and transmission mode
`determiner 160 determines the transmission user and each
`transmission mode according to a defined method using the
`information stored in the channel information/traffic require
`ment/moving speed memory 150. The traffic channel pro
`cessor 140 reads the traffic channel information stored in the
`traffic channel information memory 130 according to the
`transmission mode determined by the transmission user and
`transmission mode determiner 160, encodes and interleaves
`the traffic channel information, and maps the coded and
`interleaved traffic channel information to generate a coded/
`interleaved