Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2615—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using hybrid frequency-time division multiple access [FDMA-TDMA]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
  • H04L5/0058—Allocation criteria
  • H04L5/0073—Allocation arrangements that take into account other cell interferences
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
  • H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
  • H04L25/03866—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties using scrambling
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0014—Three-dimensional division
  • H04L5/0016—Time-frequency-code
  • H04L5/0017—Time-frequency-code in which a distinct code is applied, as a temporal sequence, to each frequency

Definitions

• the present invention relates to a wireless mobile communication system, and more
• orthogonal frequency division multiplexing OFDM
• code division OFDM
• CDMA multiple access
• a high speed data stream is divided into a plurality of low
• the OFDM system may increase symbol duration and
• OFDM OFDM Acess
• each of the sub-channels are adjacent to each other or can be uniformly spaced
• channels may cause complexity in implementation, but it may bring advantage such as
• a slot allocated to each user is defined by a 2-dimensional data region, and it is a set
• a data region in OFDMA is represented as
• axis is defined as each sub-channel.
• a data region is allocated to a specific user. But, in a uplink transmission, a data region is allocated to a specific user. But, in a
• a base station transmits data through another data region.
• the inter-cell interference is suppressed in
• the same frequency may exist in a neighbor cell, whereby the inter-user interference
• OFDM orthogonal frequency division multiplexing
• FIG. 1 shows an arranged form of OFDM sub-carriers that are widely used. In this
• fj 0, 1, 2, ... , N-I
• ⁇ f indicates a sub-carrier interval
• OFDMA is a technique of applying frequency division based on the OFDM
• the OFDMA is a system enabling several users
• FIG. 2 is a block diagram of a transmitting end of an OFDM system according to a
• FIG. 2 a transmitting end of an OFDM system according to a
• OFDM modulator 10 modulating and multiplexing data with sub-
• the OFDM modulator 10 comprises a serial/parallel (S/P) converter 10-1 converting
• a receiving end of the OFDM system has a
• the serial data converted to the baseband is converted to a
• each of the parallel-converted data is multiplexed into the sub-carrier by the IFFT unit 10-2.
• the RF end 11 converts the data multiplexed by the IFFT unit 10-2 to the RF signal and
• OFCDM orthogonal frequency code
• FIG. 3 is a block diagram of a transmitting end of an OFCDM system 25. Referring
• a transmitting end of an OFCDM system comprises an OFCDM modulator 20
• the OFCDM modulator 20 comprises a serial/parallel (S/P) converter 20-1
• code division multiplexing processing unit 20-2 multiplies each of the parallel data by a
• a receiving end of the OFCDM system has a configuration reverse to that of the
• channels is multiplexed with the orthogonal code by the CDM processing unit 20-2.
• the RF unit 21 converts the data multiplexed by the IFFT unit 20-2 of
• the OFCDM modulator 20 to the RF signal and then transmits the RF signal via at lease one
• OFDMA orthogonal frequency division multiplexing access
• the interference from load increment a cell interference averaging scheme, a cell
• the frequency reuse rate of the OFDMA system is basically smaller
• the OFDM or OFCDM technique is superior to the single frequency system or the
• CDMA system is that the problems of the selective frequency fading (in case of single
• the frequency use rate reduction multiple carrier CDMA or Nx
• CDMA CDMA based cellular mobile
• the present invention is directed to an apparatus for multiple access and
• An object of the present invention is to provide an apparatus for multiple access in a
• using OFDM in a wireless communication system comprises converting an input signal to a
• the scrambling code is used for differentiating signals transmitted in neighboring cells; and converting the substantially
• orthogonal outputs to signals by performing inverse fourier transform.
• the orthogonal outputs to signals by performing inverse fourier transform.
• scrambling code has either orthogonal or pseudo orthogonal characteristic. Moreover, a
• length of the scrambling code may be variable.
• the scrambling code is applied over
• the scrambling code comprises one of PN
• the method further comprises
• the spreading code is multiplied to each one
• communication system comprises converting an input signal to a plurality of sub-channel
• scrambling code is used for differentiating signals transmitted in neighboring cells.
• an apparatus for transmitting data using OFDM in
• a wireless communication system comprises a serial-to-parallel converter to convert an
• a processing unit operatively connected to the serial-to-parallel converter to multiply at least one of the plurality of sub-channel
• an apparatus for transmitting data using OFDM comprises a
• serial-to-parallel converter to convert an input signal to a plurality of sub-channel signals
• processor operatively connected to the transform unit to multiply at least one of the signals
• FIG. 1 is a diagram of an arranged form of OFDM sub-carriers according to related
• FIG. 2 is a block diagram of a transmitting end of an OFDM system according to
• FIG. 3 is a block diagram of a related ait OFCDM system.
• FIG. 4 is a graph for explaining an exemplary allocation of a spreading code
• FIG. 5 is a diagram of distribution of users using a cell identification spreading code
• FIG. 6 and FIG. 7 are diagrams for explaining how a CDM system is applicable to the
• present invention by taking time, frequency and code domains as references.
• FIG. 8 is a block diagram of a transmitting end of an OFDM system according to the
• FIG. 9 is a block diagram of an OFDM system according to an embodiment of the present invention.
• the present invention solves an interference problem between downlink cells using a
• each symbol to be transmitted is transmitted using carriers such as OFDMA and the like.
• OFDMA orthogonal frequency division multiplex
• the scrambling code are transmitted using frequency-time bin amounting to the number of
• codes particularly orthogonal codes are allocated to cells respectively. Therefore, other-cell
• the scrambling codes are applicable to time or frequency domain, and the
• SF is variable according to cell configuration and air channel condition.
• FIG. 4 is a graph for explaining an exemplary allocation of a scrambling code
• frequency domain is a sub-carrier and a unit of a time domain means a symbol time.
• downlink data can be transmitted using a
• a SF value may be variously applied according to a combination of a time domain
• SF_ t j me a frequency domain spreading factor
• SF_fr eq a frequency domain spreading factor
• 'SF_ fi . eq 2'.
• 'SF' is defined by 'SF_ t i me • SF_ fieq '.
• the SF itself, and the ratio of frequency domain spreading factor or the time domain
• spreading factor to the SF may be determined based on cell configuration and channel
• PN codes an OVSF (orthogonal variable spreading factor) codes are used as the PN codes.
• OVSF orthogonal variable spreading factor
• orthogonal codes Moreover, a pseudo-orthogonal code can be used as the scrambling code.
• the orthogonal code such as OVSF is preferably used.
• the SF of the above-mentioned codes is variable based on cell configuration and
• a terminal to adopt the cell identification scrambling code For example, a terminal to adopt the cell identification scrambling code
• SINR signal to interference noise ratio
• scrambling code is adopted, by combining at lease two above-mentioned methods.
• FIG. 5 is a diagram of distribution of users using a cell identification scrambling code
• the scrambling can be applied to a user in the vicinity of a base station.
• a transmission power a quantity of interference, a user's location.
• the system proposed by the present invention employs the technique of combining
• data modulation is
• OFDM OFDM
• OFCDM OFDM
• a user and channel identifying function is carried out by a CDM unit prior to IFFT.
• a CDM unit prior to IFFT.
• OFDM OFDM
• the OFCDM based method proposed by the present invention is
• identification has a user and channel identifying function also, which is performed by a
• CDM unit of an OFCDM modulator ahead of the CDM executing unit CDM unit of an OFCDM modulator ahead of the CDM executing unit.
• FIGS. 6 and 7 are diagrams for explaining how a CDM system is applicable to the
• FIG. 6 and FIG. 8 show that the code division multiplexing (CDM) scheme is used in
• the OFDMA scheme (FDM) is applied for user or channel identification,
• 'Cell 2' and 'Cell 3' in FIG. 6 indicate cells that can be identified with codes, respectively.
• the cells adjacent to each other use the same frequency band, the cells are able to
• FIG. 8 is a block diagram of a transmitting end of an OFDM system according to one
• system includes the related art OFDM modulator shown in FIG. 2 and further includes a
• code division unit 32 performing a spreading and/or scrambling function for cell
• the code division unit 32 identifies cells using spreading and scrambling scheme
• orthogonal codes for data multiplexed by the OFDM modulator 30.
• the (pseudo) orthogonal codes can be used by spreading and scrambling (non-
• orthogonal codes which include codes
• the receiving end demultiplexes an RF signal and demodulates the
• the OFDM and CDM combined system illustrated in FIG. 8 performs additional tasks
• OFDM and CDM combined system is focused on solving the cell interference problem by identifying and differentiating cells by performing code multiplexing after the OFDM
• code used for such process is preferably scrambling code described above with respect to
• FIG. 7 and FIG. 9 show that a code division scheme is applicable not only to cell
• FIG. 9 is a block diagram of a transmitting end of an OFDM system 45 according to
• OFDM system includes a code division unit 42 added to the OFDM system.
• division unit 42 identifies cells, users and channels in a manner of spreading and
• the (pseudo) orthogonal codes can be used for spreading and scrambling
• orthogonal codes include codes
• orthogonal or pseudo orthogonal codes e.g., scrambling codes
• the code division unit 42 can raise
• division unit 42 can identify one of cell, user channel, user group and channel group. Alternatively, the function of differentiating cells by using different scrambling codes may
• CDM processing unit 40-2 be implemented in the CDM processing unit 40-2.
• the CDM processing unit 40-2 the CDM processing
• unit 40-2 may incorporate the function of the code division unit 42 so that neighboring cells
• system i.e., system design flexibility
• the present invention efficiently solves the cell interference problem
• the present invention can be applied to a broadband wireless access system.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Mobile Radio Communication Systems (AREA)

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• 2006
  • 2006-02-17 WO PCT/KR2006/000546 patent/WO2006088326A2/en active Application Filing
  • 2006-02-17 EP EP06715997A patent/EP1849245A4/de not_active Ceased

Non-Patent Citations (4)

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