# US 11,909,503 B2 · Single frequency network (SFN) for broadcast/multicast application on a spotbeam satellite > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,503 B2 - Document ID: US11909503B2 - Status: Granted - Kind: B2 - Application number: 17/387,017 - Filed: 2021-07-28 - Published: 2022-02-03 - Granted: 2024-02-20 - Earliest claimed: 2020-07-28 - Assignees: ATC Technologies, LLC - Applicants: ATC Technologies, LLC - Inventors: Santanu Dutta; Dunmin Zheng - Web page: https://patentgrep.com/patent/US11909503B2 ## CPC - H04B 7/18513: {Transmission in a satellite or space-based system} - H04B 7/18515: {Transmission equipment in satellites or space-based relays} - H04B 7/18523: {Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service (arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20)} - H04B: TRANSMISSION ## Abstract Systems and methods operating a spotbeam satellite network to provide single frequency network broadcast and multicast services. One example embodiment provides a satellite broadcast system. The system includes an electronic processor communicatively coupled to a satellite and a user equipment. The electronic processor is configured to receive a plurality of bearer signals, each bearing identical broadcast program information. The electronic processor is configured to, for each of the plurality of bearer signals, generate one of a plurality of spotbeams for transmission by the satellite within a coverage area. The user equipment is configured to receive the bearer signals from a plurality of adjacent spotbeams of the plurality of spotbeams. The user equipment is configured to constructively utilize the bearer signals received from the plurality of adjacent spotbeams to decode the program information. ## Claims ### Claim 1 A method for operating a satellite network to broadcast a plurality of spotbeams within a coverage area, the method comprising: receiving, with a user equipment, bearer signals from a plurality of adjacent spotbeams of the plurality of spotbeams, wherein each of the plurality of spotbeams carries a bearer signal bearing identical broadcast program information; and constructively utilizing, with the user equipment, the bearer signals received from the plurality of adjacent spotbeams to decode the identical broadcast program information; wherein the bearer signals transmitted in each spotbeam of the plurality of adjacent spotbeams are transmitted with a differential delay with respect to the bearer signals of each of the other spotbeams of the plurality of adjacent spotbeams, and wherein the choice of the differential delay is optimized relative to constraints that include at least one selected from a group consisting of: a maximization of a received signal to noise and interference ratio; a minimization of user equipment implementation complexity; and a minimization of difference from existing terrestrial broadcast/multicast standards. ### Claim 2 (depends on 1) The method of claim 1, wherein the plurality of adjacent spotbeams are part of a cluster of adjacent spotbeams; and the bearer signals transmitted in each spotbeam of the cluster are transmitted with a differential delay with respect to the bearer signals of each of the other spotbeams of the cluster. ### Claim 3 (depends on 2) The method of claim 2, wherein the differential delay of the bearer signals for each pair of beams within the cluster is unique throughout the coverage area. ### Claim 4 (depends on 2) The method of claim 2, wherein each differential delay within a set of differential delays for the cluster is unique within the cluster; the plurality of spotbeams comprises the cluster and a second cluster; and the plurality of spotbeams of the second cluster are transmitted using a second set of differential delays, which are identical to the set of differential delays for the cluster. ### Claim 5 (depends on 2) The method of claim 2, wherein a quantity of spotbeams making up the cluster is dependent on a spatial selectivity of the plurality of spotbeams. ### Claim 6 (depends on 5) The method of claim 5, where a criterion for including a spotbeam in the cluster is that including the spotbeam would cause at least a 1 dB increase in a signal-to-noise-and-interference ratio at the user equipment. ### Claim 7 (depends on 2) The method of claim 2, where the differential delay are introduced in a ground-based beam former. ### Claim 8 (depends on 1) The method of claim 1, wherein constructively utilizing the bearer signals includes introducing frequency redundancy in a transmitted signal such that demodulation with acceptable quality is possible even when the received signal amplitudes are relatively low in certain segments of a frequency band of the transmitted signal. ### Claim 9 (depends on 8) The method of claim 8, wherein the frequency redundancy is introduced by frequency hopping across the transmitted signal bandwidth resource blocks carrying segments of the transmitted information stream and applying error correction to recover the resource blocks containing errors. ### Claim 10 A satellite broadcast system, the system comprising: an electronic processor communicatively coupled to a satellite and configured to receive a plurality of bearer signals, each bearing identical broadcast program information; for each of the plurality of bearer signals, generate one of a plurality of spotbeams for transmission by the satellite within a coverage area; and introduce into a bearer signal of each spotbeam of the plurality of spotbeams a differential delay with respect to a bearer signal of each of the other spotbeams of the plurality of spotbeams, wherein the differential delays are determined relative to constraints that include at least one selected from a group consisting of: a maximization of a received signal to noise and interference ratio; a minimization of user equipment implementation complexity; and a minimization of difference from existing terrestrial broadcast/multicast standards; and a user equipment configured to receive the plurality of bearer signals from a plurality of adjacent spotbeams of the plurality of spotbeams; and constructively utilize the plurality of bearer signals received from the plurality of adjacent spotbeams to decode the identical broadcast program information. ### Claim 11 (depends on 10) The system of claim 10, wherein the plurality of adjacent spotbeams are part of a cluster of adjacent spotbeams; and the electronic processor is further configured to introduce into a bearer signal of each spotbeam of the cluster a differential delay with respect to a bearer signal of each of the other spotbeams of the cluster. ### Claim 12 (depends on 11) The system of claim 11, wherein the differential delay of the plurality of bearer signals for each pair of beams within the cluster is unique throughout the coverage area. ### Claim 13 (depends on 11) The system of claim 11, wherein each differential delay within a set of differential delays for the cluster is unique within the cluster; the plurality of spotbeams comprises the cluster and a second cluster; and the electronic processor is further configured to introduce into the plurality of spotbeams of the second cluster a second set of differential delays, which are identical to the set of differential delays for the cluster. ### Claim 14 (depends on 11) The system of claim 11, wherein the electronic processor is further configured to determine the quantity of spotbeams making up the cluster based on a spatial selectivity of the plurality of spotbeams. ### Claim 15 (depends on 14) The system of claim 14, wherein the electronic processor is further configured to include a spotbeam in the cluster when including the spotbeam would cause at least a 1 dB increase in the signal-to-noise-and-interference ratio at the user equipment. ### Claim 16 (depends on 11) The system of claim 11, where the electronic processor is included in a ground-based beam former. ### Claim 17 (depends on 10) The system of claim 10, wherein the user equipment is configured to constructively utilize the plurality of bearer signals by introducing frequency redundancy in a transmitted signal such that demodulation with acceptable quality is possible even when the received signal amplitudes are relatively low in certain segments of a frequency band of the transmitted signal. ### Claim 18 (depends on 17) The system of claim 17, wherein the frequency redundancy is introduced by frequency hopping across the transmitted signal bandwidth resource blocks carrying segments of the transmitted information stream and applying error correction to recover the resource blocks containing errors.