# US 10,320,514 B2 · Method and apparatus for reducing preamble length in passive optical network (PON) systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,320,514 B2 - Document ID: US10320514B2 - Status: Granted - Kind: B2 - Application number: 15/583,206 - Filed: 2017-05-01 - Published: 2018-11-01 - Granted: 2019-06-11 - Earliest claimed: 2017-05-01 - Assignees: Nokia of America Corporation - Applicants: Roy B. Tebbe - Inventors: Roy B. Tebbe - Web page: https://patentgrep.com/patent/US10320514B2 ## CPC - H04J 14/0235: {for upstream transmission} - H04L 47/623: {Weighted service order} - H04Q 11/0067: {Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring} - H04Q 2011/0064: {Arbitration, scheduling or medium access control aspects} - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract A method of handling upstream data transmissions in a passive optical network includes determining signal power levels of a plurality of optical network units (ONUs); and scheduling transmissions of upstream data bursts of the plurality of ONUs by, assigning each of the upstream data bursts to one of two or more data burst groups based on the determined signal power levels, and selecting time intervals during which the upstream data bursts are transmitted in accordance with the two or more data burst groups such that the two or more data burst groups are scheduled to be transmitted sequentially. ## Claims ### Claim 1 A method of handling upstream data transmissions in a passive optical network, the method comprising: determining signal power levels of a plurality of optical network units (ONUs); and scheduling transmissions of upstream data bursts of the plurality of ONUs by, assigning each of the upstream data bursts to one of two or more data burst groups based on the determined signal power levels, and selecting time intervals during which the upstream data bursts are transmitted in accordance with the two or more data burst groups such that the two or more data burst groups are scheduled to be transmitted sequentially, wherein the scheduling of the transmissions of the upstream data bursts includes scheduling of the transmissions of the upstream data bursts such that a length of an intra-group preamble is different than a length of an inter-group preamble, the intra-group preamble being a preamble between time intervals of two consecutive upstream data bursts that belong to a same data burst group from among the two or more data burst groups, the inter-group preamble being a preamble between time intervals of two consecutive upstream data bursts that belong to two different data burst groups, respectively, from among the two or more data burst groups. ### Claim 2 (depends on 1) The method of claim 1, wherein the length of the intra-group preamble is less than the length of the inter-group preamble. ### Claim 3 (depends on 1) The method of claim 1, wherein the determining of the signal power levels of the plurality of ONUs comprises: sending ranging requests to the plurality of ONUs; receiving ranging responses from the plurality of ONUs; and measuring signal power levels of the received ranging responses. ### Claim 4 (depends on 3) The method of claim 3, wherein the determining of the signal power levels of the plurality of ONUs further comprises: for each ONU among the plurality of ONUs, determining the signal power level of the ONU to be the measured signal power level of the ranging response received from the ONU. ### Claim 5 (depends on 4) The method of claim 4, wherein the measuring of the signal power levels of the received ranging responses is based on received signal strength indicators (RSSIs) of the received ranging responses. ### Claim 6 (depends on 1) The method of claim 1, wherein the assigning comprises: determining an initial ONU from among the plurality of ONUs; determining one or more other ONUs from among the plurality of ONUs, the one or more other ONUs being ONUs, from among the plurality of ONUs, whose determined signal power levels differ from the determined signal power level of the initial ONU by less than a threshold amount; and assigning the data bursts, from among the upstream data bursts, of the initial ONU and the one or more other ONUs to a same data burst group, from among the two or more data burst groups. ### Claim 7 (depends on 6) The method of claim 6, wherein the determining of the initial ONU comprises: determining a plurality of priority categories corresponding to the plurality of ONUs by determining, for each ONU among the plurality of ONUs, a priority category to which the ONU belongs; and determining, as the initial ONU, an ONU, from among the plurality of ONUs, that belongs to a highest priority category from among the plurality of priority categories. ### Claim 8 (depends on 1) The method of claim 1 further comprising: controlling at least one ONU, from among the plurality of ONUs, to transmit a null packet during a timeslot following a timeslot in which the at least one ONU transmits an upstream data packet. ### Claim 9 (depends on 8) The method of claim 8, wherein the null packet is an unmodulated signal including all logical 1 values or all logical 0 values. ### Claim 10 A passive optical network (PON) element comprising: memory storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions such that the one or more processors are configured to, determine signal power levels of a plurality of optical network units (ONUs); and schedule transmissions of upstream data bursts of the plurality of ONUs by, assigning each of the upstream data bursts to one of two or more data burst groups based on the determined signal power levels, and selecting time intervals during which the upstream data bursts are transmitted in accordance with the two or more data burst groups such that the two or more data burst groups are scheduled to be transmitted sequentially, wherein the one or more processors are configured to execute the computer-executable instructions such that scheduling of the transmissions of the upstream data bursts includes scheduling of the transmissions of the upstream data bursts such that a length of an intra-group preamble is different than a length of an inter-group preamble, the intra-group preamble being a preamble between time intervals of two consecutive upstream data bursts that belong to a same data burst group from among the two or more data burst groups, the inter-group preamble being a preamble between time intervals of two consecutive upstream data bursts that belong to two different data burst groups, respectively, from among the two or more data burst groups. ### Claim 11 (depends on 10) The PON element of claim 10, wherein the one or more processors are configured to execute the computer-executable instructions such that the length of the intra-group preamble is less than the length of the inter-group preamble. ### Claim 12 (depends on 10) The PON element of claim 10, wherein the one or more processors are configured to execute the computer-executable instructions such that the determining of the signal power levels of the plurality of ONUs comprises: sending ranging requests to the plurality of ONUs; receiving ranging responses from the plurality of ONUs; and measuring signal power levels of the received ranging responses. ### Claim 13 (depends on 12) The PON element of claim 12, wherein the one or more processors are configured to execute the computer-executable instructions such that the determining of the signal power levels of the plurality of ONUs further comprises: for each ONU among the plurality of ONUs, determining the signal power level of the ONU to be the measured signal power level of the ranging response received from the ONU. ### Claim 14 (depends on 13) The PON element of claim 13, wherein the one or more processors are configured to execute the computer-executable instructions such that the measuring of the signal power levels of the received ranging responses is based on received signal strength indicators (RSSIs) of the received ranging responses. ### Claim 15 (depends on 10) The PON element of claim 10, wherein the one or more processors are configured to execute the computer-executable instructions such that the assigning comprises: determining an initial ONU from among the plurality of ONUs; determining one or more other ONUs from among the plurality of ONUs, the one or more other ONUs being ONUs, from among the plurality of ONUs, whose determined signal power levels differ from the determined signal power level of the initial ONU by less than a threshold amount; and assigning the data bursts, from among the upstream data bursts, of the initial ONU and the one or more other ONUs to a same data burst group, from among the two or more data burst groups. ### Claim 16 (depends on 15) The PON element of claim 15, wherein the one or more processors are configured to execute the computer-executable instructions such that the determining of the initial ONU comprises: determining a plurality of priority categories corresponding to the plurality of ONUs by determining, for each ONU among the plurality of ONUs, a priority category to which the ONU belongs; and determining, as the initial ONU, an ONU, from among the plurality of ONUs, that belongs to a highest priority category from among the plurality of priority categories. ### Claim 17 (depends on 10) The PON element of claim 10 wherein the one or more processors are configured to execute the computer-executable instructions such that the one or more processors are further configured to, control at least one ONU, from among the plurality of ONUs, to transmit a null packet during a timeslot following a timeslot in which the at least one ONU transmits an upstream data packet. ### Claim 18 (depends on 17) The PON element of claim 17, wherein the null packet is an unmodulated signal including all logical 1 values or all logical 0 values.