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公开(公告)号：BRPI0822565A2
公开(公告)日：2015-06-23
申请号：BRPI0822565
申请日：2008-04-11
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , SLIMANE SLIMANE BEN , MANSSOUR JAWAD
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Patent Agency Ranking
公开(公告)号：CA2605088C
公开(公告)日：2014-09-09
申请号：CA2605088
申请日：2006-05-17
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , LOGOTHETIS ANDREW
Abstract: A radio channel estimation technique is described for use in a OFDM-based radio communications system. A block of OFDM symbols is transmitted from multiple antennas over multiple sub-carrier frequencies. The block of OFDM symbols includes known pilot symbols as well as data symbols to be determined by a receiver. The pilot symbols are transmitted in a predetermined pattern at periodic times on periodic sub-carriers. A pilot channel estimate is determined for each pilot symbol in the received block of OFDM symbols. An NxM matrix of points corresponding to the received OFDM symbol block is formed, N is the number of sub-carriers and M is the number of OFDM symbols in the OFDM symbol block. The matrix is formed by inserting pilot channel estimates at predetermined positions in the Nx M matrix according to the predetermined pilot pattern and inserting zeros in remaining positions in the NxM matrix. A two dimensional inverse Fourier transform of the N x M matrix is calculated resulting in multiple copies of a channel estimate in the time domain. One is selected, and a two dimensional Fourier transform of the selected channel estimate is calculated to obtain a channel estimate at each point in the OFDM block.
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公开(公告)号：HK1098619A1
公开(公告)日：2007-07-20
申请号：HK07104657
申请日：2007-05-02
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , LOGOTHETIS ANDREW , ERICSON MAARTEN
Abstract: A radio base station includes multiple antennas associated with a cell. Multiple mobile radios are selected to receive transmissions over a shared radio channel during a predetermined time interval. Information is transmitted over the shared radio channel to multiple mobile radios in the cell during the predetermined time interval using multiple antenna beams. As a result, interference from the transmission appears as white additive Gaussian noise in time and in space in the cell. A "flashlight effect" caused by a single beam transmission over the shared channel during a predetermined time interval that would normally detrimentally impact mobile channel quality detection is avoided. Other methods for avoiding the flashlight effect are described.
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公开(公告)号：CA2605088A1
公开(公告)日：2006-12-14
申请号：CA2605088
申请日：2006-05-17
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , LOGOTHETIS ANDREW
Abstract: There is described a method for use in a transmitter (12) having multiple antennas (A1, A2) in an OFDM-based radio communications system, comprising determining one or more known pilot symbols. The method comprises the steps of determining a periodic pilot transmission pattern, forming a block of OFDM symbols that includes the one or more pilot symbols and data symbols in accordance with a predetermined pattern, using a space-time coder to perform space and time coding by assigning certain ones of the OFDM symbols to be transmitted during a particular time slot from a selected one the multiple antennas to provide an associated OFDM symbol stream to each of the multiple antennas, and transmitting each OFDM symbol stream from its association antenna. The space-time coder provides a first OFDM symbol stream of multiple symbols in a first sequential order to a first antenna for transmission during a first time slot and provides a second OFDM symbol stream of the same multiple symbols in a second sequential order different from the first sequential order to a second antenna.
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公开(公告)号：DE602004020485D1
公开(公告)日：2009-05-20
申请号：DE602004020485
申请日：2004-08-20
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , LOGOTHETIS ANDREW , ERICSON MARTEN
Abstract: A radio base station includes multiple antennas associated with a cell. Multiple mobile radios are selected to receive transmissions over a shared radio channel during a predetermined time interval. Information is transmitted over the shared radio channel to multiple mobile radios in the cell during the predetermined time interval using multiple antenna beams. As a result, interference from the transmission appears as white additive Gaussian noise in time and in space in the cell. A "flashlight effect" caused by a single beam transmission over the shared channel during a predetermined time interval that would normally detrimentally impact mobile channel quality detection is avoided. Other methods for avoiding the flashlight effect are described.
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公开(公告)号：CA2830386A1
公开(公告)日：2006-12-14
申请号：CA2830386
申请日：2006-05-17
Applicant: ERICSSON TELEFON AB L M
Inventor： OSSEIRAN AFIF , LOGOTHETIS ANDREW
Abstract: A radio channel estimation technique is described for use in a OFDM-based radio communications system. A block of OFDM symbols is transmitted from multiple antennas over multiple sub-carrier frequencies. The block of OFDM symbols includes known pilot symbols as well as data symbols to be determined by a receiver. The pilot symbols are transmitted in a predetermined pattern at periodic times on periodic sub-carriers. A pilot channel estimate is determined for each pilot symbol in the received block of OFDM symbols. An N × M matrix of points corresponding to the received OFDM symbol block is formed. N is the number of sub-carriers and M is the number of OFDM symbols in the OFDM symbol block. The matrix is formed by inserting pilot channel estimates at predetermined positions in the N × M matrix according to the predetermined pilot pattern and inserting zeros in remaining positions in the N × M matrix. A two dimensional inverse Fourier transform of the N × M matrix is calculated resulting in multiple copies of a channel estimate in the time domain. One is selected, and a two dimensional Fourier transform of the selected channel estimate is calculated to obtain a channel estimate at each point in the OFDM block.
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