# US 8,989,325 B2 · Multi-mode frequency domain equalization with adaptation to varying channel conditions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,989,325 B2 - Document ID: US8989325B2 - Status: Granted - Kind: B2 - Application number: 13/977,362 - Filed: 2012-01-30 - Published: 2014-10-02 - Granted: 2015-03-24 - Earliest claimed: 2012-01-30 - Assignees: Intel Corporation - Applicants: Evgeny Pustovalov; Evgeny Bakin; Andrey Turlikov - Inventors: Evgeny Pustovalov; Evgeny Bakin; Andrey Turlikov - Web page: https://patentgrep.com/patent/US8989325B2 ## CPC - H04L 25/0202: {Channel estimation} - H04L 25/0236: {using estimation of the other symbols} - H04L 25/0307: {using blind adaptation} - H04L 25/03159: {operating in the frequency domain (H04L25/03165, H04L25/03178 take precedence)} - H04N 5/21: Circuitry for suppressing or minimising disturbance, e.g. moiré or halo - H04N 21/426: Internal components of the client {; Characteristics thereof} (H04N5/44 takes precedence) - H04N 21/42607: {for processing the incoming bitstream} - H04L 2025/03579: {Modifying the tap spacing} - H04L 2025/03636: {Algorithms using least mean square [LMS]} - H04L 2025/03656: {Initialisation} - H04L 2025/03732: {according to the convergence state} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Methods and systems to configure a receiver based on a channel condition. A system may be implemented to estimate a channel based on PN sequences in a received signal, concurrently equalize a frequency domain representation of the signal with multiple blind adaptive equalizers, and evaluate results of the equalizations to select coefficients of one of the equalizers for further processing. A first equalizer may implement a constant-step-size (CSS) algorithm for a static channel. A second equalizer may implement a variable-step-size (VSS) algorithm for a dynamic channel. Static and dynamic channels may be distinguished based on convergence/divergence of the equalizers, which may be determined from a mean square error estimated from PN sequences in results of the blind equalizations. Subsequent processing may include linear and/or directed-decision equalization, channel estimation, and turbo equalization, which may be performed in the frequency domain, and which may be configurable based on the channel condition. ## Claims ### Claim 1 An apparatus to receive a signal over a channel, comprising: a first channel estimator to estimate the channel based on PN sequences of the signal; first and second adaptive blind equalizers to concurrently equalize a frequency domain representation of the received signal; a selector to select weights of one of the first and second adaptive blind equalizers based on a condition of the channel; a linear adaptive equalizer to equalize the frequency domain representation of the received signal, including to apply the selected weights as initial linear adaptive equalizer weights and to adapt the initial linear adaptive equalizer weights based on equalization results of the linear adaptive equalizer; and a decision system to generate decisions regarding the symbols based in part on the equalization results of the linear adaptive equalizer. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein: the first adaptive blind equalizer includes a constant step size (CSS) adaptive blind equalizer; and the second adaptive blind equalizer includes a variable step size (VSS) adaptive blind equalizer. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein the selector is implemented to select the weights of the CSS adaptive blind equalizer when the channel is static, and to select the weights of the VSS adaptive blind equalizer when the channel is dynamic. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the selector is further implemented to distinguish between a static channel and a dynamic channel based on an estimated mean square error determined from pseudo-random sequences in equalization results of one or more of the CSS and VSS adaptive blind equalization techniques. ### Claim 5 (depends on 2) The apparatus of claim 2, wherein the selector is implemented to: select the weights of the CSS adaptive blind equalizer when the CSS adaptive blind equalizer converges on a solution; and select the weights of the VSS adaptive blind equalizer when the CSS adaptive blind equalizer diverges from a solution. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the linear adaptive equalizer is controllable to operate in a CSS mode when the weights of the first adaptive blind equalizer are selected, and to operate in a VSS mode when the weights of the second adaptive blind equalizer are selected. ### Claim 7 (depends on 1) The apparatus of claim 1, further including: an adaptive channel estimator to adaptively estimate the channel in a CSS mode when the weights of the first adaptive blind equalizer are selected, and in a VSS mode when the weights of the second adaptive blind equalizer are selected, including to apply the PN based channel estimate as an initial channel estimate, and adapt the initial channel estimate based on prior decisions. ### Claim 8 A non-transitory computer readable medium encoded with a computer program, including instructions to cause a processor to: estimate a channel of a received signal based on PN sequences of the signal; equalize a frequency domain representation of the received signal with first and second adaptive blind equalization techniques concurrently with one another; select weights of one of the first and second adaptive blind equalization techniques based on a condition of the channel; equalize the frequency domain representation of the received signal with a an adaptive linear equalization technique, including to apply the selected weights as initial linear adaptive equalization weights and to adapt the initial linear adaptive equalization weights based on linear adaptive equalization results; and a decision system to generate decisions regarding the symbols based in part on the linear adaptive equalization results. ### Claim 9 (depends on 8) The computer readable medium of claim 8, wherein: the first adaptive blind equalization technique includes a constant step size (CSS) adaptive blind equalization technique; and the second adaptive blind equalization technique includes a variable step size (VSS) adaptive blind equalization technique. ### Claim 10 (depends on 9) The computer readable medium of claim 9, wherein the instructions include instructions to cause the processor to: select the weights of the CSS adaptive blind equalization technique when the channel is static, and to select the weights of the VSS adaptive blind equalizer when the channel is dynamic. ### Claim 11 (depends on 10) The computer readable medium of claim 10, wherein the instructions include instructions to cause the processor to: distinguish between a static channel and a dynamic channel based on an estimated mean square error determined from pseudo-random sequences in equalization results of one or more of the first and second adaptive blind equalization techniques. ### Claim 12 (depends on 9) The computer readable medium of claim 9, wherein the instructions include instructions to cause the processor to: select the weights of the CSS adaptive blind equalization technique when the CSS adaptive blind equalization technique converges; and select the weights of the VSS adaptive blind equalization technique when the CSS adaptive blind equalization technique diverges from a solution. ### Claim 13 (depends on 8) The computer readable medium of claim 8, wherein the instructions include instructions to cause the processor to: perform the linear adaptive equalization technique in a CSS mode when the weights of the first adaptive blind equalization technique are selected, and in a VSS mode when the weights of the second adaptive blind equalization technique are selected. ### Claim 14 (depends on 8) The computer readable medium of claim 8, further including instructions to cause the processor to: adaptively estimate the channel in a CSS mode when the weights of the first adaptive blind equalization technique are selected, and in a VSS mode when the weights of the second adaptive blind equalization technique are selected, including to apply the PN based channel estimate as an initial channel estimate and to adapt the initial channel estimate based on prior decisions. ### Claim 15 A system, comprising: a receiver system, including, a first channel estimator to estimate a channel of a received signal based on PN sequences of the signal, first and second adaptive blind equalizers to concurrently equalize a frequency domain representation of the received signal, a selector to select weights of one of the first and second adaptive blind equalizers based on a condition of the channel, a linear adaptive equalizer to equalize the frequency domain representation of the received signal, including to apply the selected weights as initial linear adaptive equalizer weights and to adapt the initial linear adaptive equalizer weights based on equalization results of the linear adaptive equalizer, and a decision system to generate decisions regarding the symbols based in part on the equalization results of the linear adaptive equalizer; a digital processor system to process the symbol decisions and output corresponding information to a user interface system; and a housing; wherein the receiver system and the digital processor system are positioned within the housing. ### Claim 16 (depends on 15) The system of claim 15, wherein: the signal includes a digital video broadcast signal; the digital signal processor system includes a digital video signal processor to process the decisions and output corresponding video and audio information to the user interface system; and the housing includes a television set-top box. ### Claim 17 (depends on 15) The system of claim 15, wherein: the signal includes a digital video broadcast signal; the digital signal processor system includes a digital video signal processor to process the decisions and output corresponding video and audio information to the user interface system; the user interface system includes a display, an audio system, and a human interface device (HID) to receive user input; the housing includes a portable housing; and the receiver system, the digital processor system, the user interface system, and a battery are positioned within the housing. ### Claim 18 (depends on 15) The system of claim 15, wherein: the first adaptive blind equalizer includes a constant step size (CSS) adaptive blind equalizer; the second adaptive blind equalizer includes a variable step size (VSS) adaptive blind equalizer; and the selector is implemented to select the weights of the CSS adaptive blind equalizer when the channel is static, and to select the weights of the VSS adaptive blind equalizer when the channel is dynamic. ### Claim 19 (depends on 15) The system of claim 15, wherein the linear adaptive equalizer is controllable to operate in a CSS mode when the weights of the first adaptive blind equalizer are selected, and in a VSS mode when the weights of the second adaptive blind equalizer are selected. ### Claim 20 (depends on 15) The system of claim 15, further including: an adaptive channel estimator to adaptively estimate the channel in a CSS mode when the weights of the first adaptive blind equalizer are selected, and in a VSS mode when the weights of the second adaptive blind equalizer are selected, including to apply the PN based channel estimate as an initial channel estimate, and adapt the initial channel estimate based on prior decisions.