Single-frequency broadcasting networks using multiple spotbeams
Systems and methods operating a spotbeam satellite network. 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 receives a plurality of bearer signals, each bearing identical broadcast or multicast program information. For each of the plurality of bearer signals, the electronic processor generates one of a plurality of spotbeams for transmission by the satellite within a coverage area. The electronic processor introduces into the bearer signal of each spotbeam of the plurality of spotbeams a differential delay with respect to the bearer signals of each of the other spotbeams of the plurality of spotbeams The user equipment is receives the bearer signals from a plurality of adjacent spotbeams of the plurality of spotbeams. The user equipment constructively utilizes the bearer signals received from the plurality of adjacent spotbeams to decode the program information.
1. A method for operating a satellite network broadcast or multicast service to transmit 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 or multicast program information; and
constructively utilizing, with the user equipment, the bearer signals received from the plurality of adjacent spotbeams to decode the 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 differential delay for each spotbeam of the plurality of adjacent spotbeams is selected to increase a throughput at an application layer of the broadcast or multicast service.
2. The method of claim 1 , wherein selecting the differential delay to increase a throughput at an application layer of the broadcast or multicast service includes selecting the differential delay for each spotbeam based on predicted spectra of a received signal at the user equipment that would result from the use of the delay.
3. 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.
4. The method of claim 3 , wherein the differential delay of the bearer signals for each pair of beams within the cluster is unique throughout the coverage area.
5. The method of claim 3 , 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 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.
6. The method of claim 3 , wherein the quantity of spotbeams making up the cluster is dependent on the spatial selectivities of the spotbeams.
7. The method of claim 6 , where a criterion for including a spotbeam in the cluster is that including the spotbeam would cause at least a 1 dB increase in the signal-to-noise-and-interference ratio at the user equipment.
8. The method of claim 3 , where the differential delays are introduced in a ground-based beam former.
9. 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.
10. The method of claim 9 , wherein the frequency redundancy is introduced by frequency hopping across the signal bandwidth resource blocks carrying segments of the transmitted information stream and applying error correction to recover resource blocks containing errors.
11. 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 or multicast 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 the bearer signal of each spotbeam of the plurality of spotbeams a differential delay with respect to the bearer signals of each of the other spotbeams of the plurality of spotbeams; and
a user equipment configured to
receive the bearer signals from a plurality of adjacent spotbeams of the plurality of spotbeams; and
constructively utilize the bearer signals received from the plurality of adjacent spotbeams to decode the program information.
12. The system of claim 11 , wherein the electronic processor is further configured to select the differential delay for each spotbeam based on predicted spectra of a received signal at the user equipment that would result from the use of the delay.
13. The system of claim 11 , wherein
the plurality of adjacent spotbeams are part of a cluster of adjacent spotbeams; and
the electronic processor is further configured to introduce into the bearer signal of each spotbeam of the cluster a differential delay with respect to the bearer signals of each of the other spotbeams of the cluster.
14. The system of claim 13 , wherein the differential delay of the bearer signals for each pair of beams within the cluster is unique throughout the coverage area.
15. The system of claim 13 , 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 spotbeams of the second cluster a second set of differential delays, which are identical to the set of differential delays for the cluster.
16. The system of claim 13 , wherein the electronic processor is further configured to determine the quantity of spotbeams making up the cluster based on the spatial selectivities of the spotbeams.
17. The system of claim 16 , wherein the electronic processor is further configured to include a spotbeam in the cluster when including the spotbeam would cause at least a 0 dB increase in the signal-to-noise-and-interference ratio at the user equipment.
18. The system of claim 11 , where the electronic processor is included in a ground-based beam former.
19. The system of claim 11 , wherein the user equipment is configured to constructively utilize the 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.
20. The system of claim 19 , wherein the frequency redundancy is introduced by frequency hopping across the signal bandwidth resource blocks carrying segments of the transmitted information stream and applying error correction to recover resource blocks containing errors.