# US 2013/0157560 A1 · Adaptive Fade Mitigation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0157560 A1 - Document ID: US20130157560A1 - Status: Published application - Kind: A1 - Application number: 13/664,650 - Filed: 2012-10-31 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: Gilat Satellite Networks Ltd. - Inventors: Timor Blau; Dubi Lever; Eli Shapira; Moti Goldshtein; Ori Porat - Web page: https://patentgrep.com/patent/US20130157560A1 ## CPC - H04B 7/18513: {Transmission in a satellite or space-based system} - H04B 7/18543: {for adaptation of transmission parameters, e.g. power control (for detecting or preventing errors in the information received H04L1/00)} - H04B: TRANSMISSION ## Abstract A satellite communications system comprising a Hub station and a plurality of terminals, the system is configured to utilize a FWD link and a RTN link in accordance with adaptation techniques for relevant transmission properties (e.g. modulation, coding, transmission power, etc.) and to use adaptive margins to ensure proper reception of transmitted information under various link conditions. Methods are presented for determining said adaptive margins in real time or substantially in real time, and for setting relevant transmission properties in accordance with the determined margins. Adaptive margins may be determined either directly or following the determining of a link state for each of the FWD link and the RTN link. ## Claims ### Claim 1 A method comprising: determining at a first terminal forward channel reception level estimations at first preconfigured intervals of a first duration; transmitting from the first terminal to a hub forward channel reception level estimations at second preconfigured intervals of a second duration; receiving at the hub said transmitted forward channel reception level estimations corresponding to the first terminal; determining at the hub a fade rate corresponding to the first terminal; and determining a margin corresponding to the fade rate including considering of any one or more of the following: a) a round trip delay between the hub and the first terminal, b) an interval between consecutive forward channel reception level estimations transmitted by the first terminal 103, and c) a preconfigured maximal link fade rate. ### Claim 2 (depends on 1) The method of claim 1, wherein said first duration is shorter than said second duration. ### Claim 3 (depends on 2) The method of claim 2, further comprising: determining at the first terminal one or more of a) a fade rate or b) a preferred margin, based on said forward channel reception level estimations; transmitting from the first terminal said at least one of a) fade rate or b) preferred margin to the hub; receiving at the hub at least one of a) said fade rate or b) the preferred margin, corresponding to the first terminal; determining at the hub a margin corresponding to the terminal based on at least one of a) a fade rate or b) a preferred margin received from the first terminal. ### Claim 4 (depends on 1) The method of claim 1, wherein said determining of a margin further includes: determining a forward link state corresponding to one or more consecutively determined fade rates; and determining the margin corresponding to the forward link state, wherein said determining includes considering of at least one of 1) a round trip delay between the hub and the first terminal, 2) an interval between consecutive forward channel reception level estimations transmitted by the first terminal, or 3) a preconfigured maximal link fade rate. ### Claim 5 (depends on 4) The method of claim 4, wherein determining the forward link state includes determining stable link conditions and different degrees of instability. ### Claim 6 (depends on 5) The method of claim 5, wherein determining the forward link state includes: determining a relatively low margin if the determined forward link state corresponds to stable link conditions; and determining a relatively higher margin if the determined forward link state corresponds to less than stable link conditions. ### Claim 7 (depends on 5) The method of claim 5, further including: determining that the terminal, currently associated with the stable forward link state, is associated with a less stable forward link state following a first determining that the fade rate corresponding to the terminal is higher than a first predefined threshold; and determining that the terminal, currently associated with the less than stable link state, is associated with a more stable forward link state if all one or more determined fade rates over a predefined period are lower than a second predefined threshold. ### Claim 8 (depends on 2) The method of claim 2, wherein transmitting further includes transmitting a low forward channel reception level estimation determined over a preconfigured period, longer than said second duration. ### Claim 9 (depends on 1) The method of claim 1, further including selecting a MODCOD for transmitting towards said first terminal in accordance with said margin. ### Claim 10 A method comprising: transmitting, from a terminal to a hub, a utility transmission; storing at the terminal a forward channel reception level estimation corresponding to a time of transmitting the utility transmission; receiving at the terminal a reception level estimation corresponding to the utility transmission; associating at the terminal said reception level estimation with a transmission power level used for transmitting the corresponding utility transmission; determining at the terminal a change in return link conditions based on said reception level estimation; and setting at the terminal at least a transmission power level property of a further transmitted signal in accordance with said determined return link conditions, according to said stored forward channel reception level estimation corresponding to a time of transmitting the utility transmission, and according to a forward channel reception level estimation corresponding to a time of transmitting the further transmission, wherein the difference between said forward channel reception level estimations is used for determining a transmission margin over the transmission power level based on said determined return link conditions. ### Claim 11 (depends on 10) The method of claim 10, wherein the terminal is configured to transmit utility transmissions at preconfigured intervals. ### Claim 12 (depends on 10) The method of claim 10, wherein the terminal is configured to periodically estimate the forward channel reception level, and wherein the forward channel reception level estimation corresponding to a time of transmitting the utility transmission stored by the terminal is determined at a time which does not precede the transmission time of the utility transmission by more than a periodicity interval for determining forward channel reception level estimations. ### Claim 13 (depends on 10) The method of claim 10, wherein the utility transmission includes forward channel reception level estimations. ### Claim 14 (depends on 10) The method of claim 10, wherein the system is configured to follow DVB-RCS recommendations and the utility transmission follows the format of the DVB-RCS SYNC burst. ### Claim 15 (depends on 10) The method of claim 10, wherein determining at the hub a reception level estimation further comprises measuring the reception level of the received signal. ### Claim 16 (depends on 10) The method of claim 10 further comprising determining said transmission power level based on any of a value of a programmable attenuator included in the terminal, or transmission power level measurements, which the terminal is configured to obtain from a transmitter included in the terminal. ### Claim 17 A method comprising: receiving, at a hub from a terminal, a utility transmission including transmission capability information; determining at the hub a reception level estimation for said utility transmission; determining at the hub a capability figure for the terminal based on a reception level estimation and on the transmission capability; determining at the hub capability fluctuations associated with the terminal based on consecutively determined capability information; determining at the hub a return link state corresponding to the determined capability fluctuations; and determining an allocation margin in accordance with the determined return link state, wherein a relatively low allocation margin is determined if the return link state corresponds to stable link conditions and a relatively higher allocation margin is determined if the return link state corresponds to less than stable link conditions. ### Claim 18 (depends on 17) The method of claim 17, wherein utility transmissions are transmitted at regular intervals. ### Claim 19 (depends on 17) The method of claim 17, wherein the system is configured to follow DVB-RCS recommendations and the utility transmission follows the format of the DVB-RCS SYNC burst. ### Claim 20 (depends on 17) The method of claim 17, wherein the transmissions capability information includes a distance from saturation figure. ### Claim 21 (depends on 17) The method of claim 17, wherein determining at the hub a reception level estimation for a received utility transmission further comprises measuring the reception level of the received signal. ### Claim 22 (depends on 17) The method of claim 17, wherein determining the capability figure for the terminal further comprises calculating the capability figure as the sum of determined reception level estimation and distance from saturation. ### Claim 23 (depends on 17) The method of claim 17, wherein a return link may be in one of two or more states, and wherein one of these states is associated with stable link conditions and the other one or more states are associated with link conditions of different degrees of instability. ### Claim 24 (depends on 23) The method of claim 23, further comprising: determining that the terminal, currently associated with a stable return link state, is associated with a less stable return link state following a first determining that capability fluctuations corresponding to the terminal are higher than a first predefined threshold; and determining that a terminal, currently associated with a less than stable return link state, is associated with a more stable return link state only if all one or more determined capability fluctuations over a predefined period are lower than a second predefined threshold. ### Claim 25 A satellite communication system, the system comprising a hub and at least one terminal, the system is configured to: determine at the hub a forward link state and a return link state on a per terminal basis; determine at the hub a forward link allocation margin for the terminal corresponding to a forward link state determined for the terminal; determine at the hub a return link allocation margin for the terminal corresponding to a return link state determined for the terminal; select at the hub a MODCOD for transmitting towards the terminal in accordance with a forward allocation margin corresponding to the terminal; allocate at the hub return link resources to the terminal in accordance with a return link allocation margin corresponding to the terminal; determine at the terminal return link conditions and a degradation in forward channel reception level between a time of measuring return link conditions and a time of transmitting a further transmission; and set at the terminal a transmission power level property for a further transmission in accordance with said determined return link conditions and forward channel reception level degradation. ### Claim 26 (depends on 25) The system of claim 25, wherein the hub is configured to determine a forward link state for the terminal independently of determining a return link state for the same terminal. ### Claim 27 (depends on 25) The system of claim 25, wherein the hub is configured to enforce linkage between a forward link state and a return link state determined for the same terminal and wherein: a less stable state for both the forward link and the return link is determined if any one of the forward link or the return link becomes more instable; and a more stable state for both the forward link and the return link is determined after stable conditions are determined for both links.