# US 2014/0192846 A1 · Rate adaptation for data communication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192846 A1 - Document ID: US20140192846A1 - Status: Published application - Kind: A1 - Application number: 13/738,583 - Filed: 2013-01-10 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: QUALCOMM Incorporated - Applicants: Qualcomm Incorporated - Inventors: Hassan Afkhami; Purva R. Rajkotia; Manjunath Anandarama Krishnam - Web page: https://patentgrep.com/patent/US20140192846A1 ## CPC - H04B 3/46: Monitoring; Testing - H04B 3/542: {the information being in digital form} - H04L 27/2607: {Cyclic extensions} - H04L 27/2646: {using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In some embodiments, a method includes receiving, at a receiver of a first device via a channel of a communication medium, multiple data transmissions. Each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths. The method includes determining, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate. The method includes setting a length of an adjusted guard interval for the channel for data communication from a transmitter of a second device to the receiver of the first device via the communication medium, to a length of the guard interval for the data transmission having the preferred physical data rate. ## Claims ### Claim 1 A method comprising: receiving, at a receiver of a first device via a channel of a communication medium, multiple data transmissions, wherein each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths; determining, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate; and setting a length of an adjusted guard interval for the channel for data communication from a transmitter of a second device to the receiver of the first device via the communication medium, to a length of the guard interval for the data transmission having the preferred physical data rate. ### Claim 2 (depends on 1) The method of claim 1, wherein the channel is within a number of channels in the communication medium for data communication, wherein the setting of the adjusted guard interval for the channel is performed independent of setting of a guard interval of other channels within the number of channels in the communication medium for data communication. ### Claim 3 (depends on 2) The method of claim 2, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 4 (depends on 1) The method of claim 1, wherein the multiple data transmissions comprise data packets. ### Claim 5 (depends on 1) The method of claim 1, wherein the communication medium comprises a power line. ### Claim 6 (depends on 1) The method of claim 1, further comprising transmitting, by the receiver at the first device back to the transmitter at the second device, a notification of the length for the adjusted guard interval for subsequent data transmissions. ### Claim 7 (depends on 1) The method of claim 1, further comprising: determining a noise variability of the data transmission having the preferred physical data rate at the receiver; and in response to the noise variability being above a first high noise variability threshold, adjusting the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 8 (depends on 7) The method of claim 7, further comprising: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, adjusting the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 9 (depends on 1) The method of claim 1, wherein the preferred physical data rate comprises a highest physical data rate. ### Claim 10 A method comprising: receiving, at a receiver of a first device via a channel of a communication medium, a data transmission having a number of symbols, wherein each guard interval of multiple guard intervals associated with a different set of multiple sets of the number of symbols, wherein the multiple guard intervals have different lengths; determining, based on signal characteristics of the multiple sets of the number of symbols, the set from among the multiple sets having a preferred physical data rate; and setting a length of an adjusted guard interval of the channel for subsequent data transmissions from a transmitter of a second device to the receiver of the first device via the communication medium, to a length of the guard interval associated with the set of symbols having the preferred physical data rate. ### Claim 11 (depends on 10) The method of claim 10, wherein the channel is within a number of channels in the communication medium for data communication, wherein the setting of the length of the adjusted guard interval of the channel is performed independent of setting a length of a guard interval for other channels within the number of channels in the communication medium for data communication. ### Claim 12 (depends on 11) The method of claim 11, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 13 (depends on 10) The method of claim 10, further comprising transmitting, by the receiver of the first device back to the transmitter of the second device, a notification of the length for the adjusted guard interval for subsequent data transmissions. ### Claim 14 (depends on 10) The method of claim 10, further comprising: determining a noise variability of the set of the number of symbols having the preferred physical data rate at the receiver; and in response to the noise variability being above a first high noise variability threshold, adjusting the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 15 (depends on 14) The method of claim 14, further comprising: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, adjusting the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 16 (depends on 10) The method of claim 10, wherein the preferred physical data rate comprises a highest physical data rate. ### Claim 17 A method comprising: determining a delay spread of a multipath channel for data communication from a transmitter to a receiver via a communication medium; determining a noise level of the data transmission at the receiver; and in response to the noise level being above a low noise threshold, setting a length of a guard interval for subsequent data transmissions from the transmitter to the receiver via the communication medium, based on the delay spread and the noise level at the receiver. ### Claim 18 (depends on 17) The method of claim 17, further comprising: in response to the noise level being below the low noise threshold, setting the length of the guard interval based on the delay spread and independent of the noise level at the receiver. ### Claim 19 (depends on 17) The method of claim 17, further comprising: in response to a noise variability of the data transmission being above a first high noise variability threshold, setting the length of the guard interval to a first fraction of the delay spread. ### Claim 20 (depends on 19) The method of claim 19, further comprising: in response to the noise level being above a second high noise variability threshold that is greater than the first high noise variability threshold, setting the length of the guard interval to a second fraction of the delay spread, wherein the second fraction is greater than the first fraction. ### Claim 21 (depends on 17) The method of claim 17, further comprising transmitting, by the receiver back to the transmitter, a notification of the length for the guard interval for subsequent data transmissions. ### Claim 22 An apparatus comprising: a network interface configured to receive, from a transmitter, multiple data transmissions via a channel in a communication medium, wherein each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths; a PHY rate detection unit communicatively coupled to the network interface, the PHY rate detection unit configured to determine, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate; and a guard interval selection unit configured to set a length of an adjusted guard interval for the channel for data communication from the transmitter to the apparatus via the communication media, to a length of the guard interval for the data transmission having the preferred physical data rate. ### Claim 23 (depends on 22) The apparatus of claim 22, wherein the channel is within a number of channels in the communication medium for data communication, wherein the length of the adjusted guard interval is set independent of setting guard intervals for other channels within the number of channels in the communication medium for data communication. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 25 (depends on 22) The apparatus of claim 22, wherein the multiple data transmissions comprise data packets. ### Claim 26 (depends on 22) The apparatus of claim 22, further comprising: a noise detection unit configured to determine a noise variability of the data transmission having the preferred physical data rate at the apparatus, wherein the guard interval selection unit is further configured to: in response to the noise variability being above a first high noise variability threshold, adjust the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 27 (depends on 26) The apparatus of claim 26, wherein the guard interval selection unit is further configured to: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, adjust the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 28 (depends on 22) The apparatus of claim 22, wherein the preferred physical data rate comprises a highest physical data rate. ### Claim 29 An apparatus comprising: a network interface configured to receive, from a transmitter via a communication medium, a data transmission having a number of symbols, wherein each guard interval of multiple guard intervals associated with a different set of multiple sets of the number of symbols, wherein the multiple guard intervals have different lengths; a PHY rate detection unit communicatively coupled to the network interface, the PHY rate detection unit configured to determine, based on signal characteristics of the multiple sets of the number of symbols, the set from among the multiple sets having a preferred physical data rate; and a guard interval selection unit configured to set a length of an adjusted guard interval for subsequent data transmissions from the transmitter to the apparatus via the communication medium, to a length of the guard interval associated with the set of symbols having the preferred physical data rate. ### Claim 30 (depends on 29) The apparatus of claim 29, wherein the channel is within a number of channels in the communication medium for data communication, wherein the length of the adjusted guard interval is set independent of setting guard intervals for other channels within the number of channels in the communication medium for data communication. ### Claim 31 (depends on 30) The apparatus of claim 30, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 32 (depends on 29) The apparatus of claim 29, further comprising: a noise detection unit configured to determine a noise variability of the set of the number of symbols having the preferred physical data rate at the apparatus, wherein the guard interval selection unit is further configured to: in response to the noise variability being above a first high noise variability threshold, adjust the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 33 (depends on 32) The apparatus of claim 32, wherein the guard interval selection unit is further configured to: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, adjust the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 34 (depends on 29) The apparatus of claim 29, wherein the preferred physical data rate comprises a highest physical data rate. ### Claim 35 An apparatus comprising: a network interface configured to receive, from a transmitter via a multipath channel of a communication medium, a data transmission; a delay spread detection unit communicatively coupled to the network interface, the delay spread detection unit configured to determine a delay spread of the multipath channel; a noise detection unit communicatively coupled to the network interface, the noise detection unit configured to determine a noise level of the data transmission at the apparatus; and a guard interval selection unit configured to, in response to the noise level being above a low noise threshold, set a length of a guard interval for subsequent data transmissions from the transmitter to the receiver via the communication medium, based on the delay spread and the noise level at the receiver. ### Claim 36 (depends on 35) The apparatus of claim 35, wherein the guard interval selection unit is further configured to: in response to the noise level being below the low noise threshold, set the length of the guard interval based on the delay spread and independent of the noise level at the receiver. ### Claim 37 (depends on 35) The apparatus of claim 35, wherein the guard interval selection unit is further configured to: in response to a noise variability being above a first high noise variability threshold, set the length of the guard interval to a first fraction of the delay spread. ### Claim 38 (depends on 37) The apparatus of claim 37, wherein the guard interval selection unit is further configured to: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, set the length of the guard interval to a second fraction of the delay spread, wherein the second fraction is greater than the first fraction. ### Claim 39 A computer program product for data transmission via a communication channel, the computer program product comprising: a computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising a computer usable program code configured to: receive, at a receiver of a first device via a channel of a communication medium, multiple data transmissions, wherein each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths; determine, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate; and set a length of an adjusted guard interval for the channel for data communication from a transmitter of a second device to the receiver of the first device via the communication medium, to a length of the guard interval for the data transmission having the preferred physical data rate. ### Claim 40 (depends on 39) The computer program product of claim 39, wherein the channel is within a number of channels in the communication medium for data communication, wherein the length of the adjusted guard interval is set for the channel independent of a guard interval being set for other channels within the number of channels in the communication medium for data communication. ### Claim 41 (depends on 40) The computer program product of claim 40, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 42 (depends on 39) The computer program product of claim 39, wherein the computer usable program code is further configured to: determine a noise variability of the data transmission having the preferred physical data rate at the receiver; and in response to the noise variability being above a first high noise variability threshold, adjust the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 43 (depends on 42) The computer program product of claim 42, wherein the computer usable program code is further configured to: in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, adjust the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 44 (depends on 39) The apparatus of claim 39, wherein the preferred physical data rate comprises a highest physical data rate. ### Claim 45 An apparatus comprising: means for receiving, from a transmitter, multiple data transmissions via a channel in a communication medium, wherein each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths; means for determining, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate; and means for setting a length of an adjusted guard interval for the channel for data communication from the transmitter to the apparatus via the communication media, to a length of the guard interval for the data transmission having the preferred physical data rate. ### Claim 46 (depends on 45) The apparatus of claim 45, wherein the channel is within a number of channels in the communication medium for data communication, wherein the length of the adjusted guard interval is set independent of setting guard intervals for other channels within the number of channels in the communication medium for data communication. ### Claim 47 (depends on 46) The apparatus of claim 46, wherein the length of the adjusted guard interval for the channel is different than a length of a guard interval of at least one other channel within the number of channels. ### Claim 48 (depends on 45) The apparatus of claim 45, further comprising: means for determining a noise variability of the data transmission having the preferred physical data rate at the apparatus; and means for adjusting, in response to the noise variability being above a first high noise variability threshold, the length of the adjusted guard interval to a first fraction of the adjusted guard interval. ### Claim 49 (depends on 48) The apparatus of claim 48, further comprising: means for adjusting, in response to the noise variability being above a second high noise variability threshold that is greater than the first high noise variability threshold, the length of the adjusted guard interval to a second fraction of the adjusted guard interval, wherein the second fraction is greater than the first fraction. ### Claim 50 (depends on 45) The apparatus of claim 45, wherein the preferred physical data rate comprises a highest physical data rate.