# US 10,326,632 B2 · Blind carrier synchronization method of OFDM wireless communication systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,326,632 B2 - Document ID: US10326632B2 - Status: Granted - Kind: B2 - Application number: 15/397,689 - Filed: 2017-01-03 - Published: 2017-04-27 - Granted: 2019-06-18 - Earliest claimed: 2015-08-11 - Assignees: PhasorLab, Inc. - Applicants: PhasorLab, Inc. - Inventors: Jian Cui; Joshua C. Park - Web page: https://patentgrep.com/patent/US10326632B2 ## CPC - H04L 27/26524: {Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation} - H04J 11/0036: {at the receiver} - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - H04L 27/2657: {Carrier synchronisation} - H04L 27/2659: {Coarse or integer frequency offset determination and synchronisation} - H04L 27/2676: {Blind, i.e. without using known symbols} - H04L 2025/0342: {QAM} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract A synchronizing radio receiver is disclosed, comprising: an analog baseband receive chain and a digital baseband receive chain. The digital baseband receive chain may comprise an analog to digital converter, a frame synchronization module, a frequency synchronization module, and an orthogonal frequency division multiplexing (OFDM) demodulator, wherein the frequency synchronization module is configured to cross-correlate a plurality of in-phase and quadrature samples to generate a synchronization signal and output the synchronization signal to a local oscillator in the analog baseband receive chain. The digital baseband receive chain may also further comprise a carrier frequency offset (CFO)/sampling frequency offset (SFO) correction module coupled to a frequency synchronization module configured to cross-correlate a plurality of in-phase and quadrature samples, with the CFO/SFO correction module configured to apply correction in a digital domain before outputting a corrected signal to the OFDM demodulator. ## Claims ### Claim 1 A synchronizing radio receiver for synchronization and data throughput among OFDM radios, comprising: an analog baseband receive chain, further comprising an amplifier, a mixer, and a local oscillator, the mixer mixing and outputting signals from the amplifier and the local oscillator; and a digital baseband receive chain coupled to the output of the analog baseband receive chain, further comprising an analog to digital converter, a frequency locking module, and an orthogonal frequency division multiplexing (OFDM) demodulator, wherein the frequency locking module is configured to cross-correlate a plurality of in-phase samples with a plurality of quadrature samples to generate a synchronization signal and output the synchronization signal to the local oscillator in the analog baseband receive chain. ### Claim 2 (depends on 1) The receiver of claim 1, the digital baseband receive chain further comprising a fractional n frequency synthesizer for accepting an offset clock input from an oscillator and outputting a sample rate to the analog to digital converter. ### Claim 3 (depends on 1) The receiver of claim 1, wherein the frequency locking module is further configured to cross-correlate the in-phase and quadrature samples across subcarriers. ### Claim 4 (depends on 1) The receiver of claim 1, wherein the frequency locking module is further configured to cross-correlate the in-phase and quadrature samples by computing a sum of products of either squares or absolute values of the in-phase and quadrature samples. ### Claim 5 (depends on 1) The receiver of claim 1, further comprising a plurality of receivers that are synchronized based on a base station synchronization signal, and that are continuously updated using a plurality of frequency synchronization modules outputting synchronization signals to a plurality of local oscillators. ### Claim 6 (depends on 1) The receiver of claim 1, wherein the analog baseband receive chain is configured to receive OFDM signals that are quadrature amplitude modulation (QAM) modulated in a frequency domain. ### Claim 7 (depends on 1) The receiver of claim 1, wherein the analog baseband receive chain is configured to receive OFDM signals that are wireless local area network (WLAN) or Long Term Evolution (LTE) signals. ### Claim 8 (depends on 1) The receiver of claim 1, wherein the receiver is configured to provide high data throughput using synchronization. ### Claim 9 (depends on 1) The receiver of claim 1, wherein the frequency locking module is configured to cross-correlate a plurality of in-phase samples with a plurality of quadrature samples by multiplying, for a plurality of symbols in a plurality of subcarriers in a received OFDM signal, a square of both an in-phase sample corresponding to each individual OFDM symbol and a square of a quadrature sample corresponding to the individual OFDM symbol to generate a cross-correlation for each symbol, and summing each cross-correlation of each symbol in each subcarrier, wherein the frequency locking module is configured to generate a synchronization signal based on the summed cross-correlation, and wherein the frequency locking module is further configured to output the synchronization signal to the local oscillator in the analog baseband receive chain.