Method for transmitting wideband signals via a communication system adapted for narrow-band signal transmission

• US 7,483,490 B2
• Filed: 01/17/2003
• Issued: 01/27/2009
• Est. Priority Date: 06/26/1997
• Status: Expired due to Fees

• Current Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Etemad, Kamran, Karimullah, Khalid, Sun, Feng-Wen, Lee, Lin-Nan
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US10/346,883
• Publication Number:
  US 20030108089A1
• Time in Patent Office: 2,202 Days
• Field of Search: 375/130, 375/135, 375/140, 375/141, 375/146, 375/260, 375/262, 375/265, 375/267, 370/208, 370/209, 370/335, 370/34, 370/342
• US Class Current: 375/260
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]

Abstract

A communication system is used to transmit and receive data on a plurality of relatively narrow-band signals and wideband signals. The two signal types share a common electromagnetic spectrum by employing spreading gain and maintaining orthogonality between simultaneously transmitted wideband and narrow-band signals. Signal orthogonality is maintained by selectively choosing orthogonal codes and aligning or spacing a wideband carrier frequency with respect to the narrow-band carrier frequencies in accordance with the ratio of the wideband to the narrow-band chip frequencies. A pilot signal is preferably transmitted contemporaneously with the transmission of the first spread signal, and a control date signal, associated with a plurality of users on the first bandwidth, is transmitted on a common control channel using a single Walsh code that is shared by a plurality of users in a TDMA protocol.

Claims

1. A method of transmitting a first spread signal having a first bandwidth via a communication system adapted for communicating a second signal of a second bandwidth, the second bandwidth being narrower than the first bandwidth, the method comprising:

modulating a first data signal with a first code to produce the first spread signal having the first bandwidth so that the first spread signal is orthogonal to the second signal of the second bandwidth;

transmitting the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth;

transmitting a pilot signal contemporaneously with transmission of the first spread signal; and

transmitting a control data signal, associated with a plurality of users on the first bandwidth, on a common control channel using a single Walsh code that is shared by a plurality of users in a TDMA (Time Division Multiple Access) protocol.

2. The method of claim 1, wherein the first code is associated with turbo coding.

3. The method of claim 1, wherein the modulating step is associated with a CDMA protocol.

4. The method of claim 1, wherein the first code is a Walsh code.

5. A method of transmitting a first spread signal having a first bandwidth via a communication system adapted for communicating a second signal of a second bandwidth, the second bandwidth being narrower than the first bandwidth, the method comprising:

modulating a first data signal with a first code to produce the first spread signal having the first bandwidth so that the first spread signal is orthogonal to the second signal of the second bandwidth;

transmitting the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth; and

adaptively varying a data transmission rate associated with the first spread signal in response to a transmitter power level and a data error rate.

6. A method of transmitting a first spread signal having a first bandwidth via a communication system adapted for communicating a second signal of a second bandwidth, the second bandwidth being narrower than the first bandwidth, the method comprising:

modulating a first data signal with a first code to produce the first spread signal having the first bandwidth so that the first spread signal is orthogonal to the second signal of the second bandwidth;

transmitting the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth; and

comparing a message length to a predetermined threshold for message length, and transmitting the message using the spread spectrum access channel of the first bandwidth when the message length is less than the predetermined threshold.

7. A method of transmitting a first spread signal having a first bandwidth via a communication system adapted for communicating a second signal of a second bandwidth, the second bandwidth being narrower than the first bandwidth, the method comprising:

modulating a first data signal with a first code to produce the first spread signal having the first bandwidth so that the first spread signal is orthogonal to the second signal of the second bandwidth;

transmitting the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth; and

transmitting a pilot signal contemporaneously with transmission of the first spread signal,

wherein a first carrier frequency associated with the first spread signal having a first chip rate has a spacing with respect to a second carrier frequency associated with the second signal having a second chip rate, the spacing being either an integer multiple of the ratio of the first chip rate to the second chip rate, or an odd multiple of one-half the ratio of the first chip rate to the second chip rate.

8. A method for transmitting data, comprising:

encoding a first data stream using a first code to produce a first encoded data stream;

modulating the first encoded data stream to produce a first data signal having a first bandwidth in a frequency spectrum;

encoding a second data stream using a spreading code to produce a spread signal, the spread signal having a second bandwidth in the frequency spectrum, wherein the spreading code is orthogonal to the first code;

encoding a third data stream using a third code to produce a third encoded data stream;

modulating the third encoded data stream to produce a third data signal having the first bandwidth in the frequency spectrum, wherein the spreading code is orthogonal to the third code; and

simultaneously transmitting the first data signal and the spread signal, wherein the spread signal overlays the first data signal in the frequency spectrum.

9. The method of claim 8, wherein the first and third data signals represent narrow-band signals, the method further comprising:

separating first carrier frequencies associated with the narrow-band signals from a second carrier frequency associated with the spread signal by a frequency value based on a chip rate of the narrow-band signals.

10. The method of claim 9, wherein the separating comprises:

separating the first carrier frequencies of the narrow-band signals from the second carrier frequency by a frequency value equal to an integer multiple of the chip rate associated with the narrow-band signals.

11. The method of claim 9, wherein the separating comprises:

separating the first carrier frequencies of the narrow-band signals from the second carrier frequency by a frequency value equal to an odd multiple of one half the chip rate of the narrow-band signals.

12. The method of claim 8, wherein the first code and the spreading code comprise Walsh codes.

13. The method of claim 8, wherein the spread signal comprises time division multiplexed information.

14. A system for transmitting data, comprising:

an encoder configured to encode a first data stream using at least one code to produce at least one encoded data stream;

a modulator configured to modulate the at least one encoded data stream to produce a first signal having a first bandwidth; and

a transmitter configured to simultaneously transmit the first signal and a plurality of second signals, wherein the first signal overlays the plurality of second signals in a frequency spectrum and the first signal is orthogonal to each of the plurality of second signals.

15. The system of claim 14, wherein the first signal represents a wideband signal and the plurality of second signals represent narrow-band signals, wherein carrier frequencies associated with the narrow-band signals are separated from a first carrier frequency associated with the wideband signal by a frequency value based on a chip rate of the narrow-band signals.

16. The system of claim 15, wherein the carrier frequencies associated with the narrow-band signals are separated from the first carrier frequency by a frequency value equal to an integer multiple of the chip rate associated with the narrow-band signals.

17. The system of claim 15, wherein the carrier frequencies associated with the narrow-band signals are separated from the first carrier frequency by a frequency value equal to an odd multiple of one half the chip rate of the narrow-band signals.

18. The system of claim 14, wherein the at least one code comprises at least one Walsh code.

19. A method for transmitting data, comprising:

encoding a first data stream using at least one Walsh code to produce a first encoded data stream;

modulating the first encoded data stream to produce a first data signal having a first bandwidth in a frequency spectrum; and

simultaneously transmitting the first data signal with a plurality of second signals, the plurality of second signals representing narrow-band signals, wherein the first data signal overlays the plurality of second signals in the frequency spectrum and is orthogonal to each of the plurality of second signals.

20. The method of claim 19, further comprising:

separating the narrow-band signals from a first carrier frequency associated with the first data signal by a frequency value based on a chip rate of the narrow-band signals; and

modulating the narrow-band signals with carrier signals based on the separating.

21. The method of claim 20, wherein the separating comprises:

separating the narrow-band signals from the first carrier frequency by a frequency value approximately equal to an integer multiple of the chip rate associated with the narrow-band signals.

22. The method of claim 20, wherein the separating comprises:

separating the narrow-band signals from the first carrier frequency by a frequency value approximately equal to an odd multiple of one half the chip rate of the narrow-band signals.