# US 7,412,209 B2 · Shifted channel characteristics for mitigating co-channel interference > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,412,209 B2 - Document ID: US7412209B2 - Status: Granted - Kind: B2 - Application number: 11/102,983 - Filed: 2005-04-11 - Published: 2005-10-13 - Granted: 2008-08-12 - Earliest claimed: 2004-04-12 - Assignees: The DIRECTV Group, Inc. - Inventors: Joseph Santoru; Ernest C. Chen; Shamik Maitra; Dennis Lai; Guangcai Zhou; Tung-Sheng Lin - Web page: https://patentgrep.com/patent/US7412209B2 ## CPC - H04N 5/211: {Ghost signal cancellation (H04N23/81 takes precedence)} - H04B 7/1858: {Arrangements for data transmission on the physical system, i.e. for data bit transmission between network components} - H04N 7/16: Analogue secrecy systems; Analogue subscription systems - H04N 7/163: {by receiver means only} - H04N 7/1675: {Providing digital key or authorisation information for generation or regeneration of the scrambling sequence (pseudo-random number generators in general G06F7/58)} - H04N 7/17318: {Direct or substantially direct transmission and handling of requests} - H04N 21/2347: involving video stream encryption - H04N 21/4405: involving video stream decryption - H04N 21/6143: {involving transmission via a satellite} - H04B 7/18513: {Transmission in a satellite or space-based system} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - H04B: TRANSMISSION ## Abstract Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference, and transmitting the first signal and the second signal over different channels of the communication system. ## Claims ### Claim 1 A method for minimizing co-channel interference in a communication system having at least a first signal and a second signal transmitted at the same frequency from an antenna, each signal transmitted on different channels within the communication system, comprising: shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference; and transmitting the first signal and the second signal simultaneously from the antenna over different channels of the communication system. ### Claim 2 (depends on 1) The method of claim 1, wherein the characteristic is a start time of a Start-Of-Frame (SOF) of the first signal. ### Claim 3 (depends on 2) The method of claim 2, wherein the start time is shifted at least a portion of a bit in the SOF. ### Claim 4 (depends on 1) The method of claim 1, wherein the characteristic is a transmission code schema. ### Claim 5 (depends on 4) The method of claim 4, wherein the transmission code schema is selected from a group consisting of QPSK, 8PSK, and 16ASK. ### Claim 6 (depends on 1) The method of claim 1, wherein the characteristic is an in-phase (I) portion of the first signal and a quaternary phase (Q) portion of the first signal. ### Claim 7 (depends on 6) The method of claim 6, wherein the I and Q portions of the first signal are inverted with respect to an I portion and a Q portion of the second signal. ### Claim 8 (depends on 1) The method of claim 1, wherein the characteristic is a frequency of transmission of the first signal. ### Claim 9 (depends on 1) The method of claim 1, further comprising the step of: transmitting information associated with the shifted characteristic to a receiver within the communication system. ### Claim 10 (depends on 1) The method of claim 1, wherein the characteristic is a content of the Start-Of-Frame (SOF) of the first signal. ### Claim 11 (depends on 10) The method of claim 10, wherein the content is selected from a preselected set of contents for the SOF. ### Claim 12 A method for minimizing co-channel interference in a satellite-based communication system having at least a first signal and a second signal transmitted at the same frequency from an antenna, each signal comprising at least a header and a payload, each signal being transmitted on different channels within the communication system, comprising: shifting at least one characteristic of the first signal with respect to a corresponding characteristic of the second signal to mitigate co-channel interference between thc first signal and the second signal; and transmitting the first signal and the second signal simultaneously from the antenna over different channels of the communication system. ### Claim 13 (depends on 12) The method of claim 12, wherein the characteristic is a transmission code schema. ### Claim 14 (depends on 13) The method of claim 13, wherein the transmission code schema is selected froma group consisting of QPSK, 8PSK, and 16ASK. ### Claim 15 (depends on 14) The method of claim 14, wherein the characteristic further includes a start time of a Start-Of-Frame (SOF) of the first signal. ### Claim 16 (depends on 15) The method of claim 15, wherein the start time is shifted at least a portion of a bit. ### Claim 17 (depends on 16) The method of claim 16, wherein the characteristic further includes an in-phase (I) portion of the first signal and a quaternary phase (Q) portion of the first signal. ### Claim 18 (depends on 17) The method of claim 17, wherein the I and Q portions of the first signal are inverted with respect to an I portion and a Q portion of the second signal. ### Claim 19 (depends on 18) The method of claim 18, wherein the characteristic is a frequency of transmission of the first signal. ### Claim 20 (depends on 19) The method of claim 19, further comprising the step of: transmitting information associated with the shifted characteristic to a receiver within the communication system.