Configuration of overhead channels in a mixed bandwidth system

• US 7,447,189 B2
• Filed: 06/28/2004
• Issued: 11/04/2008
• Est. Priority Date: 04/23/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jou, Yu-Cheun
• Primary Examiner(s): Pham; Chi H.
• Assistant Examiner(s): Elallam; Ahmed
• Application Number:
  US10/879,787
• Publication Number:
  US 20050007977A1
• Time in Patent Office: 1,590 Days
• Field of Search: 370/320, 370/335, 370/342, 370/441, 375/261, 375/275, 375/298, 455450-451, 455/552.1
• US Class Current: 370/342
• CPC Class Codes: H04L 27/262 Reduction thereof by selection of pilot symbols
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority

Abstract

A method and apparatus for transmitting broadcast information in a multi-carrier communication system. The Sync Channel of the multi-carrier system is transmitted a 1.25 MHz channel bandwidth (i.e., over a single carrier), and to specify the preferred channels for the Sync Channel transmission instead of the preferred channels for the entire multi-carrier system. The Sync Channel Message will carry additional information indicating the center frequency of a multi-carrier system within a reserved set of frequency bands and indicating the frequency of a single carrier system in the reserved set of frequency bands. Considering the A block of the PCS band again, the preferred channels for Sync Channel transmission can be selected as channels 75, 150 and 225. This selection ensures that one of the preferred channels will always be used by any multi-carrier system regardless of the location of its center channel.

Claims

1. A receiver operable in at least one of a multi-carrier mode in a multi-carrier system and a single carrier mode in a single carrier system, comprising:

an antenna that receives a forward link signal;

a first subsystem, coupled to the antenna, configured to down convert and demodulate a first component of the forward link signal at a first carrier frequency to generate a first demodulated component of the forward link signal, wherein the first carrier frequency corresponds to a first preferred channel of a selected set of preferred channels that includes a pilot signal; and

a second subsystem, coupled to the antenna, configured to down convert and demodulate a second component of the forward link signal at a second carrier frequency to generate a second demodulated component of the forward link signal, wherein the second carrier frequency corresponds to a second preferred channel of the selected set of preferred channels; and

a processor that instructs the first subsystem to tune to the first preferred channel at the first carrier frequency, and attempts to detect a pilot signal on the first preferred channel,

wherein if the pilot signal is detected on the first preferred channel the receiver receives a sync channel message, and

wherein if the pilot signal is not detected on the first preferred channel, the processor instructs the second subsystem to tune to the second preferred channel at the second carrier frequency of the selected set of preferred channels.

2. A receiver according to claim 1, wherein if sufficient correlation energy is detected by the processor, the pilot signal is detected and the receiver demodulates, de-interleaves and decodes the sync channel message.

3. A receiver according to claim 2, wherein the processor determines whether the receiver will operate in the multi-carrier mode or the single carrier mode.

4. A receiver according to claim 1, wherein the first subsystem comprises:

a first receiver, coupled to the antenna, that down converts, filters and amplifies the forward link signal at the first carrier frequency, corresponding to the first preferred channel of the selected set of preferred channels, to generate the first component of the forward link signal, and

a first demodulator that demodulates the first component of the forward link signal to generate the first demodulated component of the forward link signal, wherein the processor instructs the first receiver to tune to the first preferred channel at the first carrier frequency, and attempts to acquire the pilot signal at the first carrier frequency using the first demodulator.

5. A receiver according to claim 4, if the pilot signal is not detected on the first preferred channel the processor instructs the second subsystem to tune to the second preferred channel of the selected set of preferred channels, and wherein the second subsystem comprises:

a second receiver, coupled to the antenna, that down converts, filters and amplifies the forward link signal at the second carrier frequency to generate the second component of the forward link signal, wherein the second carrier frequency corresponds to the second preferred channel of the selected set of preferred channels, and

a second demodulator that demodulates the second component of the forward link signal to generate the second demodulated component of the forward link signal,

wherein the processor instructs the second receiver to tune to the second preferred channel at the second carrier frequency, and

wherein the processor attempts to acquire the pilot signal at the second carrier frequency using the second demodulator.

6. A receiver according to claim 5, further comprising:

a third subsystem, coupled to the antenna, configured to down convert and demodulate a third component of the forward link signal at a third carrier frequency to generate a third demodulated component of the forward link signal, wherein the third carrier frequency corresponds to a third preferred channel of the selected set of preferred channels; and

if the pilot signal is not detected on the second preferred channel the processor instructs the third subsystem to tune to the third preferred channel, and wherein the third subsystem comprises;

a third receiver, coupled to the antenna, that down converts, filters and amplifies the forward link signal at the third carrier frequency to generate the third component of the forward link signal, and

a third demodulator that demodulates the third component of the forward link signal to generate the third demodulated component of the forward link signal,

wherein the processor instructs the third receiver to tune to the third preferred channel at the third carrier frequency, and

wherein the processor attempts to acquire the pilot signal at the third carrier frequency using the third demodulator.

7. A receiver according to claim 6, wherein if the processor decides to operate in the single-carrier mode then the receiver determines the frequency of a single carrier system from the sync channel message, tunes to the frequency indicated in the sync channel message and begins to receive the forward link signal on the first carrier frequency.

8. A receiver according to claim 6, wherein if the processor decides to operate in the multi-carrier mode, then the receiver determines a center frequency of the multi-carrier system from the sync channel message, and the processor activates the RF circuitry in the second and third receivers, tunes to the appropriate set of frequencies indicated in the sync channel message and begins to receive the forward link signal.

9. A receiver according to claim 6, further comprising:

a multiplexer that re-assembles demodulated components of the forward link signal from each of the first, second and third subsystems.

10. A receiver according to claim 2, wherein the first demodulator comprises:

a quaternary phase shift keyed receiver and outputs an In-phase (I) and Quadrature (Q) component of the forward link signal.

11. A receiver according to claim 10, wherein the first demodulator further comprises:

a complex PN despreader that despreads the I and Q components using two pseudonoise sequences.

12. A receiver according to claim 11, wherein the first demodulator further comprises:

a control processor that provides offset hypotheses to said complex PN despreader,

wherein the complex PN despreader despreads the I and Q components using offset hypotheses provided by the control processor and a first orthogonal sequence to generate a resultant signal; and

a pilot filter that despreads the resultant signal using the first orthogonal sequence and filters the despread resultant signal to generate samples.

13. A receiver according to claim 12, wherein the first demodulator further comprises:

an energy detector that sums squares of the samples to provide pilot energy values,

wherein the control processor compares the pilot energy values to a threshold value.

14. A receiver according to claim 13, wherein if the pilot energy values exceed the threshold value, the I and Q components are despread using a PN offset, and the pilot signal is processed by a pilot filter.

15. A receiver according to claim 13, wherein the control processor provides a next PN hypothesis to the complex PN despreader if the pilot energy values fall below the threshold value, and after exhausting all hypotheses, instructs the second receiver to down convert the down link signal at the second carrier frequency if the received pilot energy values fail to exceed the threshold value.

16. A receiver according to claim 14, wherein the first demodulator further comprises:

a Walsh despreader that despreads the PN despread signal using a Walsh code sequence for transmission of the sync channel message to generate a Walsh despread signal; and

a dot product circuit that computes a projection of the Walsh despread signal onto the pilot signal to provide a scalar output.

17. A receiver according to claim 16, wherein the first demodulator further comprises:

a multiplexer that uses the scalar output to generate a signal data symbol stream;

a de-interleaver that reorders the signal data symbols of the signal data symbol stream using predetermined de-interleaving format; and

a decoder that decodes the reordered symbols of the sync channel message to provide the sync channel message.

18. A receiver according to claim 17, wherein the control processor receives the sync channel message, determines from the sync channel message a channel frequency for a primary overhead channel of the single carrier system, and tunes the first subsystem to the appropriate channel to receive the forward link signal.

19. A receiver according to claim 17, wherein the control processor receives the sync channel message, determines a center frequency of the multi-carrier system, and tunes subsystems to the appropriate channels to receive the forward link signal.

20. A method of operating a receiver in at least one of a multi-carrier mode in a multi-carrier system and a single carrier mode in a single carrier system, comprising:

receiving a forward link signal;

providing a selected set of preferred channels that includes a pilot signal;

generating a first demodulated component of the forward link signal by down converting and demodulating a first component of the forward link signal at a first carrier frequency that corresponds to a first preferred channel of the selected set of preferred channels;

tuning to the first preferred channel at the first carrier frequency;

attempting to detect a pilot signal on the first preferred channel, wherein if the pilot signal is detected on the first preferred channel the receiver receives a sync channel message;

if the pilot signal is not detected on the first preferred channel, generating a second demodulated component of the forward link signal by down converting and demodulating a second component of the forward link signal at a second carrier frequency that corresponds to a second preferred channel of the selected set of preferred channels; and

tuning to the second preferred channel at the second carrier frequency of the selected set of preferred channels.

21. A method according to claim 20, further comprising:

if the pilot signal is not detected on the second preferred channel, generating a third demodulated component of the forward link signal by down converting and demodulating a third component of the forward link signal at a third carrier frequency that corresponds to a third preferred channel of the selected set of preferred channels; and

tuning to the third preferred channel at the third carrier frequency of the selected set of preferred channels.

22. A method according to claim 20, wherein if sufficient correlation energy is detected, the pilot signal is detected and the sync channel message is demodulated, de-interleaved and decoded.

23. A method according to claim 21, further comprising:

deciding whether the receiver will operate in the multi-carrier mode or the single carrier mode.

24. A method according to claim 23, wherein if the receiver operates in the single-carrier mode, further comprising:

receiving the sync channel message;

determining the first carrier frequency of a single carrier system from the sync channel message;

tuning to the first preferred channel indicated in the sync channel message to receive the forward link signal; and

receiving the forward link signal on the first carrier frequency.

25. A method according to claim 24, wherein the first carrier frequency of the single carrier system comprises a channel frequency for a primary overhead channel of the single carrier system.

26. A method according to claim 23, wherein if the receiver operates in the multi-carrier mode, further comprising:

receiving the sync channel message;

determining a center frequency of the multi-carrier system from the sync channel message;

tuning to the appropriate set of frequencies indicated in the sync channel message to receive the forward link signal; and

receiving the forward link signal.

27. An apparatus for operating a receiver in at least one of a multi-carrier mode in a multi-carrier system and a single carrier mode in a single carrier system, comprising:

means for receiving a forward link signal;

means for providing a selected set of preferred channels that includes a pilot signal;

means for generating a first demodulated component of the forward link signal by down converting and demodulating a first component of the forward link signal at a first carrier frequency that corresponds to a first preferred channel of the selected set of preferred channels;

means for tuning to the first preferred channel at the first carrier frequency;

means for attempting to detect a pilot signal on the first preferred channel, wherein if the pilot signal is detected on the first preferred channel the receiver receives a sync channel message;

if the pilot signal is not detected on the first preferred channel, generating a second demodulated component of the forward link signal by down converting and demodulating a second component of the forward link signal at a second carrier frequency that corresponds to a second preferred channel of the selected set of preferred channels; and

means for tuning to the second preferred channel at the second carrier frequency of the selected set of preferred channels.

28. The apparatus according to claim 27, further comprising:

if the pilot signal is not detected on the second preferred channel, generating a third demodulated component of the forward link signal by down converting and demodulating a third component of the forward link signal at a third carrier frequency that corresponds to a third preferred channel of the selected set of preferred channels; and

means for tuning to the third preferred channel at the third carrier frequency of the selected set of preferred channels.

29. The apparatus according to claim 27, wherein if sufficient correlation energy is detected, the pilot signal is detected and the sync channel message is demodulated, de-interleaved and decoded.

30. The apparatus according to claim 28, further comprising:

means for deciding whether the receiver will operate in the multi-carrier mode or the single carrier mode.

31. The apparatus according to claim 30, wherein if the receiver operates in the single-carrier mode, further comprising:

means for receiving the sync channel message;

means for determining the first carrier frequency of a single carrier system from the sync channel message;

means for tuning to the first preferred channel indicated in the sync channel message to receive the forward link signal; and

means for receiving the forward link signal on the first carrier frequency.

32. The apparatus according to claim 31, wherein the first carrier frequency of the single carrier system comprises a channel frequency for a primary overhead channel of the single carrier system.

33. The apparatus according to claim 31, wherein if the receiver operates in the multi-carrier mode, further comprising:

means for receiving the sync channel message;

means for determining a center frequency of the multi-carrier system from the sync channel message;

means for tuning to the appropriate set of frequencies indicated in the sync channel message to receive the forward link signal; and

means for receiving the forward link signal.