# US 10,771,302 B2 · Channel probing signal for a broadband communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,302 B2 - Document ID: US10771302B2 - Status: Granted - Kind: B2 - Application number: 15/953,950 - Filed: 2018-04-16 - Published: 2019-03-21 - Granted: 2020-09-08 - Earliest claimed: 2004-01-29 - Assignees: Neo Wireless LLC - Applicants: Neo Wireless LLC - Inventors: Xiaodong Li; Titus Lo; Kemin Li; Haiming Huang - Web page: https://patentgrep.com/patent/US10771302B2 ## CPC - H04B 1/707: using direct sequence modulation - H04B 1/711: the interference being multi-path interference - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - H04L 5/0028: {Variable division (indication of the divided channel H04L5/0092)} - H04L 25/03834: {using pulse shaping} - H04L 27/0008: {arrangements for allowing a transmitter or receiver to use more than one type of modulation (negotiating modulation type for two-way transmission paths H04L5/1453)} - H04L 27/0012: {arrangements for identifying the type of modulation} - H04L 27/2602: {Signal structure} - H04L 27/2626: {Arrangements specific to the transmitter only} - H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)} - H04L 5/0016: {Time-frequency-code} - H04L 25/0228: {with direct estimation from sounding signals} - H04L 27/2607: {Cyclic extensions} - H04L 27/2655: {Synchronisation arrangements} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In a broadband wireless communication system, a spread spectrum signal is intentionally overlapped with an OFDM signal, in a time domain, a frequency domain, or both. The OFDM signal, which inherently has a high spectral efficiency, is used for carrying broadband data or control information. The spread spectrum signal, which is designed to have a high spread gain for overcoming severe interference, is used for facilitating system functions such as initial random access, channel probing, or short messaging. Methods and techniques are devised to ensure that the mutual interference between the overlapped signals is minimized to have insignificant impact on either signal and that both signals are detectable with expected performance by a receiver. ## Claims ### Claim 1 A communication method for a mobile device in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the method comprising: receiving a request for a probing signal from a base station in the system; and transmitting, in response to the received request, the probing signal with a code sequence modulated in the frequency domain, wherein: the probing signal is configured to overlap, in the time domain, with uplink signals transmitted over an uplink frequency band by other mobile devices in the system; and the probing signal is configured to occupy a portion of spectrum in the uplink frequency band not designated for transmission of uplink control signals in the system. ### Claim 2 (depends on 1) The method of claim 1, wherein the probing signal provides information for the base station to estimate a channel profile in the frequency domain. ### Claim 3 (depends on 2) The method of claim 2, wherein the mobile device receives a subsequent transmission from the base station that has been beamformed using the estimated channel profile. ### Claim 4 (depends on 1) The method of claim 1, wherein the probing signal provides information for the base station to determine a transmission format for a subsequent transmission. ### Claim 5 (depends on 4) The method of claim 4, wherein the transmission format comprises a modulation/coding or pilot pattern. ### Claim 6 (depends on 1) The method of claim 1, wherein the portion of spectrum is available for transmission of uplink data signals by other mobile devices in the system during a time period when the portion of the spectrum is not occupied by the probing signal. ### Claim 7 (depends on 1) The method of claim 1, wherein the portion of spectrum is within a center portion of the uplink frequency band and subcarriers for the transmission of uplink control signals are within an outer portion of the uplink frequency band. ### Claim 8 A communication method for a base station in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the method comprising: transmitting a request for a probing signal to a mobile device in the system; and receiving the probing signal from the mobile device, wherein: the probing signal contains a code sequence modulated in the frequency domain; the probing signal overlaps, in the time domain, with uplink signals transmitted over an uplink frequency band by other mobile devices in the system; and the probing signal occupies a portion of spectrum in the uplink frequency band not designated for transmission of uplink control signals in the system. ### Claim 9 (depends on 8) The method of claim 8, further comprising estimating, based on the received probing signal, a channel profile in the frequency domain. ### Claim 10 (depends on 9) The method of claim 9, further comprising using the channel profile to determine a transmission format for a subsequent transmission over the channel. ### Claim 11 (depends on 10) The method of claim 10, wherein the transmission format comprises a modulation/coding or pilot pattern. ### Claim 12 (depends on 9) The method of claim 9, further comprising using the channel profile for beamforming in a subsequent transmission to the mobile device. ### Claim 13 (depends on 8) The method of claim 8, wherein the portion of spectrum is available for transmission of uplink data signals by other mobile devices in the system during a time period when the portion of the spectrum is not occupied by the probing signal. ### Claim 14 (depends on 8) The method of claim 8, wherein the portion of spectrum is within a center portion of the uplink frequency band and subcarriers for the transmission of uplink control signals are within an outer portion of the uplink frequency band. ### Claim 15 A communication method for an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the method comprising: sending a request for a probing signal to a mobile device from a base station in the system; and responding by the mobile device to the request by transmitting the probing signal with a code sequence modulated in the frequency domain, wherein: the probing signal is configured to overlap, in the time domain, with uplink signals transmitted over an uplink frequency band by other mobile devices in the system; and the probing signal is configured to occupy a portion of spectrum in the uplink frequency band not designated for transmission of uplink control signals in the system. ### Claim 16 (depends on 15) The method of claim 15, wherein transmission power of the probing signal is under power control. ### Claim 17 (depends on 15) The method of claim 15, wherein the probing signal enables the base station to estimate a channel profile in the frequency domain. ### Claim 18 (depends on 17) The method of claim 17, wherein the channel profile is used by the base station to determine a transmission format for a subsequent transmission. ### Claim 19 (depends on 18) The method of claim 18, wherein the transmission format comprises a modulation/coding or pilot pattern. ### Claim 20 (depends on 17) The method of claim 17, wherein the channel profile is used for beamforming in a subsequent transmission by the base station to the mobile device. ### Claim 21 (depends on 15) The method of claim 15, wherein the portion of spectrum is available for transmission of uplink data signals by other mobile devices in the system during a time period when the portion of the spectrum is not occupied by the probing signal. ### Claim 22 (depends on 15) The method of claim 15, wherein the portion of spectrum is within a center portion of the uplink frequency band and subcarriers for the transmission of uplink control signals are within an outer portion of the uplink frequency band. ### Claim 23 A mobile device in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the mobile device comprising: a receiver configured to receive a request for a probing signal from a base station in the system; a transmitter configured to form and transmit, in response to the received request, the probing signal with a code sequence modulated in the frequency domain, wherein: the probing signal is configured to overlap, in the time domain, with uplink signals transmitted over an uplink frequency band by other mobile devices in the system; and the probing signal is configured to occupy a portion of spectrum in the uplink frequency band not designated for transmission of uplink control signals in the system. ### Claim 24 (depends on 23) The mobile device of claim 23, wherein the probing signal provides information for the base station to estimate a channel profile in the frequency domain. ### Claim 25 (depends on 24) The mobile device of claim 24, wherein the mobile device is configured to receive a subsequent transmission from the base station that has been beamformed using the estimated channel profile. ### Claim 26 (depends on 23) The mobile device of claim 23, wherein the probing signal provides information for the base station to determine a transmission format for a subsequent transmission. ### Claim 27 (depends on 26) The mobile device of claim 26, wherein the transmission format comprises a modulation/coding or pilot pattern. ### Claim 28 (depends on 23) The mobile device of claim 23, wherein the portion of spectrum is available for transmission of uplink data signals by other mobile devices in the system during a time period when the portion of the spectrum is not occupied by the probing signal. ### Claim 29 (depends on 23) The mobile device of claim 23, wherein the portion of spectrum is within a center portion of the uplink frequency band and subcarriers for the transmission of uplink control signals are within an outer portion of the uplink frequency band. ### Claim 30 A base station in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the base station comprising: a transmitter configured to transmit a request for a probing signal to a mobile device in the system; and a receiver configured to receive the probing signal from the mobile device, wherein: the probing signal contains a code sequence modulated in the frequency domain; the probing signal overlaps, in the time domain, with uplink signals transmitted over an uplink frequency band by other mobile devices in the system; and the probing signal occupies a portion of spectrum in the uplink frequency band not designated for transmission of uplink control signals in the system. ### Claim 31 (depends on 30) The base station of claim 30, wherein the receiver is further configured to estimate, based on the received probing signal, a channel profile in the frequency domain. ### Claim 32 (depends on 31) The base station of claim 31, further comprising using the channel profile to determine a transmission format for a subsequent transmission over the channel. ### Claim 33 (depends on 32) The base station of claim 32, wherein the transmission format comprises a modulation/coding or pilot pattern. ### Claim 34 (depends on 31) The base station of claim 31, further comprising using the channel profile for beamforming in a subsequent transmission to the mobile device. ### Claim 35 (depends on 30) The base station of claim 30, wherein the portion of spectrum is available for transmission of uplink data signals by other mobile devices in the system during a time period when the portion of the spectrum is not occupied by the probing signal. ### Claim 36 (depends on 30) The base station of claim 30, wherein the portion of spectrum is within a center portion of the uplink frequency band and subcarriers for the transmission of uplink control signals are within an outer portion of the uplink frequency band.