# US 8,570,918 B2 · System and method for processing a frequency division multiplexing signal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,918 B2 - Document ID: US8570918B2 - Status: Granted - Kind: B2 - Application number: 13/106,681 - Filed: 2011-05-12 - Published: 2012-05-17 - Granted: 2013-10-29 - Earliest claimed: 2010-11-15 - Assignees: National Chiao Tung University - Applicants: Hai-wei Wang; David W. Lin; Tzu-Hsien Sang - Inventors: Hai-wei Wang; David W. Lin; Tzu-Hsien Sang - Web page: https://patentgrep.com/patent/US8570918B2 ## CPC - H04L 25/03821: {Inter-carrier interference cancellation [ICI]} - H04L 25/03159: {operating in the frequency domain (H04L25/03165, H04L25/03178 take precedence)} - H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method for processing a frequency division multiplexing signal transmitted in a channel is provided. The method includes the steps of a) receiving the frequency division multiplexing signal having a residual intercarrier interference (ICI) and a channel noise and transmitted by plural subcarriers; b) performing a cyclic prefix removal and a discrete Fourier transform for the frequency division multiplexing signal to obtain a frequency-domain signal; c) analyzing the frequency-domain signal to obtain a plurality of correlation values for the residual ICI and the channel noise; and d) performing a communication signal processing for the frequency division multiplexing signal based on at least one of the plural correlation values. ## Claims ### Claim 1 A method for processing a frequency division multiplexing signal transmitted in a channel, comprising steps of: a) receiving the frequency division multiplexing signal having a residual intercarrier interference (ICI) and a channel noise and transmitted in plural subcarriers; b) performing a cyclic prefix removal and a discrete Fourier transform for the frequency division multiplexing signal to obtain a frequency-domain signal; c) analyzing the frequency-domain signal to obtain a plurality of correlation values for the residual ICI and the channel noise; d) performing a communication signal processing for the frequency division multiplexing signal based on at least one of the plural correlation values; and e) performing a signal detection method for the frequency-domain signal, wherein the signal detection method includes a maximum likelihood sequence estimation, and the maximum likelihood sequence estimation is performed based on a sum-form log-likelihood function. ### Claim 2 (depends on 1) A method of claim 1, wherein the residual ICI comes from at least one of a time-varying channel and a carrier frequency shift. ### Claim 3 (depends on 1) A method of claim 1, wherein the frequency division multiplexing signal comprises one selected from a group consisting of an orthogonal frequency division multiplexing signal, an orthogonal frequency division multiple access signal, a single-carrier frequency-domain equalization signal, a single-carrier frequency division multiplexing signal and a single-carrier frequency division multiple access signal. ### Claim 4 (depends on 1) A method of claim 1, wherein the step d) is performed by at least one of whitening on the frequency division multiplexing signal, and obtaining a channel information parameter after a computation based on at least one of the plural correlation values. ### Claim 5 (depends on 1) A method of claim 1, wherein the signal detection method is performed in the communication signal processing. ### Claim 6 (depends on 1) A method of claim 1, wherein the step d) further comprises a step of providing one of a receiver and a transmitter for performing the communication signal processing, which includes a closed loop transmission control mechanism. ### Claim 7 (depends on 1) A method of claim 1, wherein the step d) further comprises a step of providing a transmitter for performing the communication signal processing, which includes a channel sounding mechanism. ### Claim 8 (depends on 1) A method of claim 1, wherein in step c), the correlation values are ones selected from a group consisting of an estimated average power of the residual ICI and the channel noise, an estimated average power of the residual ICI, an estimated average power of the channel noise, an estimated correlation value of the residual ICI and a combination thereof. ### Claim 9 (depends on 1) A method of claim 1, wherein in step c), at least one of the correlation values is obtained by using a decision circuit's output to subtract a main signal from the frequency-domain signal and then using a result to compute a sample-average correlation. ### Claim 10 (depends on 1) A method of claim 1, wherein in step c), at least one of the correlation values is obtained from a known correlation value by using a known relationship between two of the correlation values. ### Claim 11 A frequency division multiplexing communication system, having a plurality of correlation values and comprising: a channel for transmitting a frequency division multiplexing signal, which is transmitted by plural subcarriers and has a frequency-domain signal including a residual intercarrier interference (ICI) and a channel noise; and a first means for receiving the frequency-domain signal, and processing a communication signal based on the plural correlation values of a sum of the residual ICI and the channel noise, wherein the communication signal is processed through a whitening operation on the sum of the residual ICI and the channel noise at a frequency-domain. ### Claim 12 (depends on 11) A system of claim 11, having a closed loop transmission control mechanism and further comprising: a second means, based on the closed loop transmission control mechanism, for obtaining one selected from a group consisting of the plural correlation values for the residual ICI and the channel noise, the channel information parameter, a maximum Doppler frequency shift, an average power of the residual ICI and a combination thereof, so as to adjust a method of transmitting the frequency division multiplexing signal. ### Claim 13 (depends on 12) A system of claim 12, wherein the method of transmitting the frequency division multiplexing signal comprises one selected from a group consisting of a transmission antenna array configuration, a channel coding, a modulation, a pre-coding, an adjustment of a discrete Fourier transform size, an adjustment of a cyclic prefix size and a combination thereof. ### Claim 14 (depends on 12) A system of claim 12, wherein the second means comprises a transmitter. ### Claim 15 (depends on 11) A system of claim 11, where the first means comprises a receiver. ### Claim 16 (depends on 11) A system of claim 11, wherein the communication signal is further processed through an obtainment of a channel information parameter after a computation based on at least one of the plural correlation values.