Synchronized broadcast/multicast communication

• US 8,582,621 B2
• Filed: 01/05/2011
• Issued: 11/12/2013
• Est. Priority Date: 01/20/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Grob, Matthew S., Black, Peter J., Jayaraman, Srikant, Jacobs, Paul E.
• Primary Examiner(s): DEPPE, BETSY LEE
• Application Number:
  US12/985,333
• Publication Number:
  US 20110134967A1
• Time in Patent Office: 1,042 Days
• Field of Search: 375/141, 375/146, 375/147, 375/259, 375/260, 375/395, 375/316, 375/340, 375/95, 375/295, 370/328, 370/335, 370/342, 370/432, 370/441, 455/500, 455/501, 455/502, 455/503
• US Class Current: 375/146
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 5/026 using code division

Abstract

Synchronized broadcast transmits a same broadcast content using a same waveform from multiple transmitters. Transmitters each apply a same spreading code for broadcast transmissions. In a spread-spectrum communication system having a time division multiplexed forward link, a synchronized broadcast transmission is inserted into a broadcast slot. One embodiment employs an Orthogonal Frequency Divisional Multiplex (OFDM) waveform for the synchronized broadcast. An OFDM receiver is then used to process the received synchronized broadcast transmission. An alternate embodiment implements a broadcast Pseudo-random Noise (PN) code for use by multiple transmitters. An equalizer is then employed to estimate the synchronized broadcast transmission.

Claims

1. A computer-implemented method of synchronized broadcast transmission in a spread-spectrum communication system, the method comprising:

spreading, by a first transmitter of a base station, unicast information using a first spreading code specific to the first transmitter; and

time-synchronized spreading, by the first transmitter with respect to at least a second transmitter, broadcast information using a broadcast spreading code common to the first transmitter and the at least second transmitter, wherein the broadcast information is the same for the first transmitter and the at least second transmitter; and

transmitting in synchronization the broadcast information from the first transmitter and the at least second transmitter.

2. The computer-implemented method of claim 1, wherein transmitting the broadcast information includes transmitting a transmission having a plurality of time slots, the transmission comprising a plurality of code division modulated slots and a synchronized broadcast slot that includes the broadcast information.

3. The computer-implemented method of claim 2, wherein the plurality of code division modulated slots include the unicast information.

4. The computer-implemented method of claim 3, wherein the broadcast information is transmitted using orthogonal frequency division modulation.

5. The computer-implemented method of claim 1, wherein transmitting in synchronization the broadcast information comprises transmitting information from the first transmitter and the at least second transmitter in at least one time slot.

6. The computer-implemented method of claim 1, further comprising multiplexing the broadcast information and the unicast information into one transmission time slot.

7. The computer-implemented method of claim 6, wherein the one transmission time slot includes a broadcast pilot.

8. The computer-implemented method of claim 1, wherein the broadcast information is transmitted at least in part during an interlace reserved for broadcast transmissions.

9. The computer-implemented method of claim 8, wherein the broadcast information includes one or more physical layer packets transmitted by the first transmitter and by the second transmitter during the interlace.

10. The computer-implemented method of claim 1, wherein the broadcast spreading code is a pseudonoise (PN) code.

11. A receiver compatible with a spread-spectrum communication system, the receiver comprising:

means for receiving unicast information spread using a first spreading code specific to a first transmitter of a base station that transmitted the unicast information and further for receiving broadcast information from the first transmitter and at least a second transmitter, the at least second transmitter transmitting the broadcast information in synchronization with the first transmitter, the broadcast information spread using a time synchronized broadcast spreading code common to the first transmitter and to the at least second transmitter; and

a demodulation controller coupled to the means for receiving.

12. The receiver of claim 11, further comprising:

means for demodulating unicast transmissions including the unicast information; and

means for demodulating broadcast transmissions including the broadcast information,

wherein the demodulation controller comprises means for selecting the means for demodulating unicast transmissions or the means for demodulating broadcast transmissions in response to a type of information received.

13. The receiver of claim 12, wherein the means for demodulating unicast transmissions is configured to demodulate code division modulated information.

14. The receiver of claim 12, wherein the means for demodulating broadcast transmissions is configured to demodulate orthogonal frequency division modulated information.

15. The receiver of claim 11, wherein the means for receiving the unicast information and for receiving the broadcast information is compatible with a time division multiplex forward link format.

16. The receiver of claim 11, wherein the means for receiving is configured to receive a first transmission slot, wherein the first transmission slot includes the broadcast information modulated using a first modulation format and further includes a unicast portion including the unicast information modulated using a second modulation format, wherein the first and second modulation formats are different, and further comprising:

means for demodulating the unicast portion; and

means for demodulating the broadcast portion,

wherein the demodulation controller comprises means for selecting, in response to a type of information received, the means for demodulating the unicast portion or the means for demodulating the broadcast portion.

17. The receiver of claim 16, wherein the first modulation format comprises an orthogonal frequency division modulation format.

18. The receiver of claim 16, wherein the second modulation format comprises a code division modulation format.

19. The receiver of claim 16, wherein the first modulation format comprises a code division modulation format corresponding to a broadcast spreading code used by multiple transmitters.

20. The receiver of claim 16, wherein the means for demodulating the broadcast portion comprises means for equalizing the broadcast portion.

21. The receiver of claim 20, wherein the means for equalizing the broadcast portion comprises means for training an equalizer using a broadcast pilot of the broadcast portion.

22. An apparatus, comprising:

a first transmitter of a base station, the first transmitter configured to;

spread unicast information using a first spreading code specific to the first transmitter; and

time-synchronized spread, by the first transmitter with respect to at least a second transmitter, broadcast information using a broadcast spreading code common to the first transmitter and the at least second transmitter, wherein the broadcast information is the same for the first transmitter and the at least second transmitter; and

transmit in synchronization the broadcast information from the first transmitter and the at least second transmitter.

23. The apparatus of claim 22, wherein the first transmitter is further configured to transmit the broadcast information by transmitting a transmission having a plurality of time slots, the transmission comprising a plurality of code division modulated slots and a synchronized broadcast slot that includes the broadcast information.

24. The apparatus of claim 23, wherein the unicast information is transmitted in the plurality of code division modulated slots.

25. The apparatus of claim 23, wherein the broadcast information is transmitted using orthogonal frequency division modulation.

26. The apparatus of claim 22, wherein transmitting in synchronization the broadcast information comprises transmitting information from the first transmitter and the at least second transmitter in at least one time slot.

27. A non-transitory computer readable medium comprising instructions operable, when executed by a processor, to cause the processor to:

receive unicast information spread using a first spreading code specific to a first transmitter of a base station; and

receive broadcast information from the first transmitter and at least a second transmitter, the at least second transmitter transmitting the broadcast information in synchronization with the first transmitter, the broadcast information spread using a time synchronized broadcast spreading code common to the first transmitter and to the at least second transmitter.

28. The non-transitory computer readable medium of claim 27, wherein the instructions are further operable, when executed by the processor, to cause the processor to:

demodulate unicast transmissions; and

demodulate broadcast transmissions.

29. The non-transitory computer readable medium of claim 27, wherein the instructions are further operable, when executed by the processor, to cause the processor to estimate received information.

30. The non-transitory computer readable medium of claim 29, wherein the instructions are further operable, when executed by the processor, to cause the processor to:

identify a broadcast pilot signal; and

equalize the received broadcast information using the broadcast pilot signal.

31. The non-transitory computer readable medium of claim 30, wherein the instructions are further operable, when executed by the processor, to cause the processor to equalize the received broadcast information and to equalize the received unicast information.

32. The non-transitory computer readable medium of claim 27, wherein the processor is further configured to demodulate code division modulated information.

33. The non-transitory computer readable medium of claim 27, wherein the processor is further configured to demodulate orthogonal frequency division modulated information.