# US 8,094,732 B2 · Method and device for estimating a multicarrier signal propagation channel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,094,732 B2 - Document ID: US8094732B2 - Status: Granted - Kind: B2 - Application number: 10/564,866 - Filed: 2004-07-16 - Published: 2007-02-22 - Granted: 2012-01-10 - Earliest claimed: 2003-07-18 - Assignees: Tdf - Inventors: Bruno Jahan; Pierrick Louin - Web page: https://patentgrep.com/patent/US8094732B2 ## CPC - H04L 25/0232: {by interpolation between sounding signals} - H04L 25/022: {of frequency response} - H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)} - H04L 27/2657: {Carrier synchronisation} - H04L 2027/003: {at baseband only} - H04L 2027/0093: {Intermittant signals} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method is provided for estimating a propagation channel composed of successive symbols of a multicarrier signal, each comprising at least one reference pilot and a plurality of data-carrying frequencies. Such a method comprises, in particular, at least one step consisting of correcting the at least one reference pilot on the basis of a first estimation of a propagation channel, in order to provide a second, more precise estimation of the channel. ## Claims ### Claim 1 Process comprising: estimating a propagation channel formed by successive symbols of a multi-carrier signal, each symbol comprising at least one reference pilot and a plurality of frequencies carrying data, wherein estimating comprises: extracting said at least one reference pilot present in each of said symbols; and for each of said symbols: obtaining a first estimate of said propagation channel, by time/frequency interpolation on said extracted at least one reference pilot; independently correcting each of said at least one reference pilot, in phase and amplitude, and as a function of said first estimate, to output a corrected pilot with phase and amplitude correction, said correction step including a step to calculate an amplitude and phase error vector for each of said at least one reference pilot; and obtaining a second estimate of said propagation channel, by analysis of said corrected pilot. ### Claim 2 (depends on 1) Process for estimating a propagation channel according to claim 1, wherein said error vector calculation step includes averaging of a set of error vectors obtained on at least one symbol. ### Claim 3 (depends on 2) Process for estimating a propagation channel according to claim 2, wherein said averaging is calculated on each symbol. ### Claim 4 (depends on 2) Process for estimating a propagation channel according to claim 2, wherein said set of error vectors only includes error vectors that satisfy at least one predetermined quality criterion. ### Claim 5 (depends on 1) Process for estimating a propagation channel according to claim 1, wherein said calculation step for an amplitude and phase error vector comprises a preliminary step in which said pilots with an amplitude less than a first predetermined minimum average threshold and/or greater than a second predetermined maximum average threshold are rejected. ### Claim 6 (depends on 1) Process for estimating a propagation channel according to claim 1, wherein said second estimate includes an equalisation step that depends on the first estimate. ### Claim 7 (depends on 6) Process for estimating a propagation channel according to claim 6, wherein said equalisation step is performed on all carrier frequencies of each of said symbols. ### Claim 8 (depends on 6) Process for estimating a propagation channel according to claim 6, wherein the process comprises a step after said equalisation step to calculate a pulse response of the propagation channel as a function of the at least one reference pilot equalized by the equalization step, for refining synchronisation of receivers in time. ### Claim 9 (depends on 1) Process for estimating a propagation channel according to claim 1, wherein said the reference pilot correction step includes a division of these pilots by the first estimate. ### Claim 10 (depends on 2) Process for estimating a propagation channel according to claim 2, wherein said correction step of the at least one reference pilot also includes a final step to correct all equalised useful carriers taking account of an average value obtained as a result of said averaging. ### Claim 11 (depends on 1) Process for estimating a propagation channel according to claim 1, and further comprising using the process for correction of at least one phase and/or amplitude error common to two cells in a same OFDM (Orthogonal Frequency Division Multiplex) type symbol. ### Claim 12 A device comprising: means for estimating a propagation channel formed of successive symbols of a multi-carrier signal, each symbol comprising at least one reference pilot, and a plurality of data carrier frequencies, the means for estimating comprising: means for extracting said at least one reference pilot present in each of said symbols; and means for obtaining estimates of said propagation channel, which comprises, for each of said symbols: making a first estimate of said propagation channel, by time/frequency interpolation on said extracted at least one reference pilot; independently correcting each of said at least one reference pilot, in phase and amplitude, as a function of said first estimate, to output at least one corrected pilot with phase and amplitude correction, said correction step including a step to calculate an amplitude and phase error vector for each of said at least one reference pilot; and making a second estimate of said propagation channel, by analysis of said at least one corrected pilot with phase and amplitude correction. ### Claim 13 A device comprising: a channel estimator device configured to estimate a propagation channel formed of successive symbols of a multi-carrier signal, each symbol comprising at least one reference pilot, and a plurality of data carrier frequencies, the channel estimator device comprising: an extraction element, which extracts the at least one reference pilot present in each of said symbols; and a first estimation element, which makes a first estimate of the propagation channel, for each of said symbols, by time/frequency interpolation on the extracted at least one reference pilot; a correction element, which for each of said symbols independently corrects the at least one reference pilot, in phase and amplitude, as a function of the first estimate, to output at least one corrected pilot with phase and amplitude correction, said correction step including a step to calculate an amplitude and phase error vector for each of said at least one reference pilot; and a second estimation element, which for each of said symbols makes a second estimate of said propagation channel, by analysis of the at least one corrected pilot with phase and amplitude correction. ### Claim 14 A process comprising: estimating a propagation channel formed by successive symbols of a multi-carrier signal, each symbol comprising at least one reference pilot and a plurality of frequencies carrying data, wherein estimating comprises: extracting said at least one reference pilot present in each of said symbols; and for each of said symbols: obtaining a first estimate of said propagation channel, by time/frequency interpolation on said extracted at least one reference pilot; independently correcting each of said at least one reference pilot, in phase and amplitude, and as a function of said first estimate, to output a corrected pilot with phase and amplitude correction, said correction step including a step to calculate an amplitude and phase error vector for each of said at least one reference pilot, which comprises a preliminary step in which said pilots with an amplitude less than a first predetermined minimum average threshold and/or greater than a second predetermined maximum average threshold are rejected; and obtaining a second estimate of said propagation channel, by analysis of said corrected pilot.