Spectrum sharing between broadcasting and multiple-access networks
Advantage is taken of the fact that broadcast coverage is unevenly distributed across a geographical region and multiple-access transmissions can be interposed in regions where interference is minimum. In one embodiment, advantage is taken of the known broadcasting signal and techniques, such as, for example, dirty paper coding techniques, can be used to pre-cancel broadcasting differences, allowing a system to operate as if the interference did not exist.
1 . A wireless system comprising:
a broadcast transmission operating within a certain frequency spectrum, said broadcast transmission operating at relatively high power;
a multiple-access transmission operating within said same certain frequency spectrum, each said multiple-access transmission at a significantly lower power level than said broadcast transmission; and
interference apparatus for canceling interference between said broadcast and multiple-access transmissions as seen by the respective receivers of both said broadcast and multiple-access transmissions.
2 . The system of claim 1 wherein said interference apparatus uses, at least in part, dirty paper coding techniques.
3 . The system of claim 1 wherein said transmission is TV transmission within a frequency spectrum assigned for publicly available TV.
4 . The system of claim 3 wherein said multiple access transmission is OFDMA.
5 . The system of claim 4 wherein the broadcast power spectrum is spread over a number of multiple-access user channels.
6 . The system of claim 1 wherein said interference apparatus is operative for allowing for the initial establishment of a multiple-access user transmission without said cancellation.
7 . A wireless communication system comprising:
a modulation scheme for controlling multiple access transmission from a base station to specific ones of mobile user terminals; and
signal grooming circuitry for allowing said multiple access transmission to be acceptably received by said users even when broadcast signals are present in the same frequency spectrum as said transmission, acceptability being defined as a bit error rate less than a predefined threshold.
8 . The system of claim 7 wherein said defined threshold is 1 % or less.
9 . The system of claim 7 wherein said grooming circuitry uses, at least in part, dirty paper coding techniques.
10 . The system of claim 7 wherein said multiple access transmission is OFDMA.
11 . The system of claim 7 wherein the broadcast power spectrum is spread over a number of multiple-access user channels.
12 . The system of claim 7 wherein said grooming circuitry is operative for allowing for the initial establishment of a multiple-access user transmission without said cancellation.
13 . A method of operating a broadcast transmission system in a frequency spectrum that overlaps the frequency spectrum of a multiple-access, said method comprising:
grooming said broadcast transmissions to remove interference from said multiple-access transmissions; and
grooming said multiple-access transmissions to remove interference from said broadcast transmissions.
14 . The method of claim 13 wherein each said grooming takes into account the modulation techniques of the other transmission system.
15 . A method for operating a wireless system, said method comprising:
broadcasting RF transmissions at relatively high power within a certain frequency spectrum;
broadcasting multiple-access RF transmissions within said same certain frequency spectrum, each said multiple-access RF transmissions broadcast at a significantly lower power level than said broadcast transmissions; and
canceling interference between said broadcasted RF transmissions and said broadcasted multiple-access transmissions, said cancellations as seen by the respective receivers of both said broadcast and multiple-access RF transmissions.
16 . The method of claim 15 wherein said interference apparatus uses, at least in part, dirty paper coding techniques.
17 . The method of claim 15 wherein said multiple access RF transmissions are in the OFDMA format.
18 . The method of claim 17 wherein the broadcast power spectrum is spread over a number of multiple-access user channels.
19 . The method of claim 15 wherein said cancellation comprises:
allowing for the initial establishment of a multiple-access RF transmission without said cancellation.
20 . The method of claim 15 wherein said RF transmission is a TV transmission within a frequency spectrum assigned for publicly available TV.