System and method for descrambling the phase of carriers in a multicarrier communications system
View Patent ↗A system and method that demodulates the phase characteristic of a carrier signal are described. The scrambling of the phase characteristic of each carrier signal includes associating a value with each carrier signal and computing a phase shift for each carrier signal based on the value associated with that carrier signal. The value is determined independently of any input bit value carried by that carrier signal. The phase shift computed for each carrier signal is combined with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristic of the carrier signals. Bits of an input signal are modulated onto the carrier signals having the substantially scrambled phase characteristic to produce a transmission signal with a reduced PAR.
1. A method, in a first transceiver that uses a plurality of carrier signals for receiving a bit stream that was transmitted by a second transceiver, wherein each carrier signal has a phase characteristic associated with the bit stream, the method comprising:
receiving the bit stream from the second transceiver, wherein:
each carrier signal is associated with a value determined independently of any bit value of the bit stream carried by that respective carrier signal, the value associated with each carrier signal determined by a pseudo-random number generator,
a phase shift for each carrier signal is at least based on:
the value associated with that carrier signal, and
the combining of a phase for each carrier signal with the phase characteristic of that respective carrier signal so as to substantially scramble the phase characteristics of the plurality of carrier signals, and
multiple carrier signals corresponding to the plurality of phase shifted and scrambled carrier signals are used by the first transceiver to demodulate a same bit value of the received bit stream; and
wherein:
the first and second transceivers communicate over one or more of a pair of twisted wires of a telephone subscriber line and fiber optic, and
the first and second transceivers transport video.
2. The method of claim 1 , wherein the first transceiver is a cable transceiver.
3. The method of claim 1 , wherein the first transceiver is VDSL transceiver.
4. The method of claim 1 , wherein the first and second transceivers are multicarrier DSL transceivers.
5. The method of claim 1 , wherein the first and second transceivers are used for high speed internet access.
6. The method of claim 1 , further comprising, in the second transceiver, independently deriving the values associated with each carrier using a second pseudo-random number generator in the second transceiver.
7. The method of claim 6 , wherein the first and second transceivers use a same seed for the pseudo-random number generator.
8. The method of claim 6 , wherein the first and second transceivers are wireless transceivers.
9. The method of claim 6 , wherein the first and second transceivers are cable transceivers.
10. The method of claim 6 , wherein the first and second transceivers are DSL transceivers connected using a pair of twisted wires of a telephone subscriber system.
11. The method of claim 10 , wherein the first and second transceivers are VDSL transceivers.
12. The method of claim 6 , wherein the first and second transceivers are multicarrier DSL transceivers.
13. The method of claim 6 , wherein the first and second transceivers are also used for transport high speed internet access.
14. A communication system including a first transceiver that uses a plurality of carrier signals for receiving a bit stream that was transmitted by a second transceiver, wherein each carrier signal has a phase characteristic associated with the bit stream, the transceiver capable of receiving from the second transceiver the bit stream, wherein:
each carrier signal is associated with a value determined independently of any bit value of the bit stream carried by that respective carrier signal, the value associated with each carrier signal determined by a pseudo-random number generator,
a phase shift for each carrier signal is at least based on:
the value associated with that respective carrier signal, and
the combining of a phase shift for each carrier signal with the phase characteristic of that respective carrier signal so as to substantially scramble the phase characteristics of the plurality of carrier signals, and
multiple carrier signals corresponding to the plurality of phase shifted and scrambled carrier signals are used by the first transceiver to demodulate a same bit value of the received bit stream; and
wherein:
the first and second transceivers communicate over one or more of a pair of twisted wires of a telephone subscriber line and fiber optic, and
the first and second transceivers transport video.
15. The system of claim 14 , wherein the first transceiver is a cable transceiver.
16. The system of claim 14 , wherein the first transceiver is VDSL transceiver.
17. The system of claim 14 , wherein the first and second transceivers are multicarrier DSL transceivers.
18. The system of claim 14 , wherein the first and second transceiver are used for high speed internet access.
19. The system of claim 14 , further comprising the second transceiver independently deriving the values associated with each carrier using a second pseudo-random number generator in the second transceiver.
20. The system of claim 19 , wherein the first and second transceivers use a same seed for the pseudo-random number generator.
21. The system of claim 19 , wherein the first and second transceivers are wireless transceivers.
22. The system of claim 19 , wherein the first and second transceivers are cable transceivers.
23. The system of claim 19 , wherein the first and second transceivers are DSL transceivers connected using a pair of twisted wires of a telephone subscriber system.
24. The system of claim 23 , wherein the first and second transceivers are VDSL transceivers.
25. The system of claim 19 , wherein the first and second transceivers are multicarrier DSL transceivers.
26. The system of claim 19 , wherein the first and second transceivers are also used for high speed internet access.
27. The method of claim 14 , wherein the first and second transceivers each include a digital signal processor.
28. The method of claim 1 , wherein the first and second transceivers each include a digital signal processor.
29. The method of claim 1 , wherein the video is video-on demand.
30. The method of claim 14 , wherein the video is video-on demand.
31. A method, in a first transceiver that uses a plurality of carrier signals for receiving a bit stream that was transmitted by a second transceiver, wherein each carrier signal has a phase characteristic associated with the bit stream, the method comprising:
receiving the bit stream from the second transceiver, wherein:
each carrier signal is associated with a value determined independently of any bit value of the bit stream carried by that respective carrier signal, the value associated with each carrier signal determined by a pseudo-random number generator,
a phase shift for each carrier signal is at least based on:
the value associated with that carrier signal, and
the combining of a phase for each carrier signal with the phase characteristic of that respective carrier signal so as to substantially scramble the phase characteristics of the plurality of carrier signals, and
multiple carrier signals corresponding to the plurality of phase shifted and scrambled carrier signals are used by the first transceiver to demodulate a same bit value of the received bit stream; and
wherein:
the first and second transceivers communicate over one or more of a pair of twisted wires of a telephone subscriber line and fiber optic, and
the first and second transceivers are used for internet access.