Time-divided transmission between adjacent cells
View Patent ↗In a DVB-T network, a single channel is shared between transmitters associated with adjacent cells on a time-division basis. Timing allocation information signals are received at each transmitter, where it is determined therefrom and from a common time reference, such as a GPS receiver or atomic clock, when transmission is and is not allowed. Each of the transmitters then transmits on the channel at different times. The channel may carry Internet Protocol Data Cast Services. The timing allocation may be varied so that transmitters have unequal shares. The allocation may be dynamically controllable depending on demand. Using the invention, a saving of frequency spectrum is obtained without requiring channel rasterisation.
1. A network, the network comprising:
at least two broadcast transmitters, said at least two broadcast transmitters being arranged to effect a cellular coverage pattern, said cellular coverage pattern comprising at least two cells, each of said at least two broadcast transmitters being associated with each of said at least two cells, said at least two broadcast transmitters comprising a first transmitter associated with a first cell and a second broadcast transmitter associated with a second cell, said second cell being adjacent to said first cell,
wherein said first and second broadcast transmitters are arranged to broadcast content data signals at a particular frequency on a time-divided basis, said content data being broadcast in bursts, each of said bursts comprising at least one packet, and
wherein said first transmitter is arranged to include in a header of one or more of said at least one packet signal timing allocation information, said signal timing allocation information identifying when said bursts are broadcast from said first broadcast transmitter.
2. A network as claimed in claim 1 , in which each of a group of broadcast transmitters, the group comprising broadcast transmitters associated with a given cells and with plural adjacent cells, is arranged such that no two broadcast transmitters in the group broadcast at the same frequency at the same time at a power level sufficient to cause significant interference in an adjacent cell.
3. A network as claimed in claim 2 , in which the broadcast transmitters in a group are allocated approximately equal amounts of time on which they are permitted to transmit.
4. A network as claimed in claim 2 , in which the broadcast transmitters in a group are allocated unequal amounts of time in which they are permitted to broadcast.
5. A network as claimed in claim 2 , in which the network comprises plural groups arranged in a repeating pattern.
6. A network as claimed in claim 1 , in which each broadcast transmitter is arranged to control instances of broadcast on the basis of the time as determined from a common time reference.
7. A network as claimed in claim 1 , in which the signals relate to audio-visual content.
8. A network as claimed in claim 1 , in which the network is a digital video broadcasting network.
9. A network as claimed in claim 8 , in which at least some of the signals relate to Internet Protocol Data Cast services.
10. A network as claimed in claim 1 , in which the signal timing allocation information comprises absolute times of starting and stopping broadcast.
11. A network as claimed in claim 1 , in which the signal timing allocation information comprises a duration of the burst and an interval between bursts.
12. A network as claimed in claim 11 , in which the interval includes a guard period.
13. A network as claimed in claim 1 , in which the signal timing allocation information comprises an interval between an end of a burst and a beginning of the next burst.
14. A network as claimed in claim 1 , in which the signal timing allocation information comprises a frame or subframe number, from which starting and stopping times can be derived.
15. A method of operating a network, the method comprising:
providing at least two broadcast transmitters, said at least two broadcast transmitters being arranged to effect a cellular coverage pattern, said cellular coverage pattern comprising at least two cells, each of said at least two broadcast transmitters being associated with each of said at least two cells, said at least two broadcast transmitters comprising a first transmitter associated with a first cell and a second broadcast transmitter associated with a second cell, said second cell being adjacent to said first cell,
controlling said first and second broadcast transmitters to broadcast content data signals at a given frequency on a time-divided basis, said content data being broadcast in bursts, each of said bursts comprising at least one packet; and
including in a header of one or more of said at least one packet of signal timing allocation information, said signal timing allocation information identifying when said bursts are broadcast from said first broadcast transmitter.
16. A method as claimed in claim 15 , the method comprising controlling each of a group of broadcast transmitters, the group comprising broadcast transmitters associated with a given cell and with plural adjacent cells, such that no two broadcast transmitters in the group broadcast at the same frequency at the same time at a power level sufficient to cause significant interference in an adjacent cell.
17. A method as claimed in claim 16 , comprising allocating broadcast transmitters in a group approximately equal amounts of time on which they are permitted to broadcast.
18. A method as claimed in claim 16 , comprising allocating the broadcast transmitters in a group unequal amounts of time on which they are permitted to broadcast.
19. A method as claimed in claim 15 , comprising controlling each broadcast transmitter to effect instances of broadcast on the basis of the time as determined from a common time reference.
20. A method as claimed in claim 15 , in which the signals relate to audio-visual content.
21. A method as claimed in claim 15 , in which the network is a digital video broadcasting network.
22. A method as claimed in claim 21 , in which at least some of the signals relate to Internet Protocol Data Cast services.
23. A method as claimed in claim 15 , in which the signal timing allocation information comprises absolute times of starting and stopping broadcast.
24. A method as claimed in claim 15 , in which the signal timing allocation information comprises a duration of the burst and an interval between bursts.
25. A method as claimed in claim 24 , in which the interval includes a guard period.
26. A method as claimed in claim 15 , in which the signal timing allocation information comprises an interval between an end of a burst and a beginning of the next burst.
27. A method as claimed in claim 15 , in which the signal timing allocation information comprises a frame or subframe number, from which starting and stopping times can be derived.
28. A broadcast transmitter for operating with at least one other broadcast transmitter in a network to effect a cellular coverage pattern, said broadcast transmitter comprising a controller, said controller being arranged to:
receive signal timing allocation information;
control broadcast of content data signals, said content data signals being broadcast in bursts, each of said bursts comprising at least one packet;
control broadcast of said bursts at a given frequency and only at times determined to be permissible by comparison of said received signal timing allocation information to a source of reference time; and
include in a header of one or more packets of the broadcast content data signal timing allocation information, said signal timing allocation information identifying when said bursts are broadcast from said broadcast transmitter.
29. A broadcast transmitter as claimed in claim 28 , in which the signal timing allocation information comprises absolute times of starting and stopping broadcast.
30. A broadcast transmitter as claimed in claim 28 , in which the signal timing allocation information comprises a duration of the burst and an interval between bursts.
31. A broadcast transmitter as claimed in claim 30 , in which the interval includes a guard period.
32. A broadcast transmitter as claimed in claim 28 , in which the signal timing allocation information comprises an interval between an end of a burst and a beginning of the next burst.
33. A broadcast transmitter as claimed in claim 28 , in which the signal timing allocation information comprises a frame or subframe number, from which starting and stopping times can be derived.
34. A method of operating a broadcast transmitter with other broadcast transmitters in a network to effect a cellular coverage pattern, the method comprising:
receiving signal timing allocation information;
comparing said received signal timing allocation information to a source of reference time;
determining time periods in which broadcasts content data signals are permissible on the basis of said comparing step;
controlling said broadcast transmitter to broadcast content data signals, said content data signals being broadcast in bursts, said burst being broadcast at a given frequency only during said time periods; and
including in a header of one or more packets of the broadcast content data signal timing allocation information, said signal timing allocation information identifying when said bursts are broadcast from said broadcast transmitter.
35. A method as claimed in claim 34 , in which the signal timing allocation information comprises absolute times of starting and stopping broadcast.
36. A method as claimed in claim 34 , in which the signal timing allocation information comprises a duration of the burst and an interval between bursts.
37. A method as claimed in claim 36 , in which the interval includes a guard period.
38. A method as claimed in claim 34 , in which the signal timing allocation information comprises an interval between an end of a burst and a beginning of the next burst.
39. A method as claimed in claim 34 , in which the signal timing allocation information comprises a frame or subframe number, from which starting and stopping times can be derived.