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

• US 6,539,050 B1
• Filed: 06/25/1998
• Issued: 03/25/2003
• Est. Priority Date: 06/26/1997
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Inventors: Sun, Feng-Wen, Lee, Lin-Nan, Etemad, Kamran, Karimullah, Khalid
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US09/104,467
• Time in Patent Office: 1,734 Days
• Field of Search: 375/146, 375/141, 375/140, 375/130, 370/206, 370/208, 370/209, 370/335, 370/342, 370/337, 370/347
• US Class Current: 375/146
• 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 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 spreaded signal, and a control data 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. Further, if the length of the message intended for transmission by the wideband transceivers is below a message length threshold, the message can be transmitted using a common access channel shared by the wideband transceivers. Still further, by adapting the data transmission rate, in response to the data error rate and transmitter power level, the transmission range and/or the data transmission rate can be optimized.

Claims

1. A method for 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 the steps of:

modulating a first data signal with a particular orthogonal code to produce the first spread signal having the first bandwidth so that the first spread signal is subsequently 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 the message length, and transmitting a message using a spread spectrum access channel of the first bandwidth when the message length is less than the predetermined threshold.

2. A method for 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 the steps of:

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

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

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 second chip rate, or an odd multiple of one-half the ratio of the first chip rate to the second chip rate.

3. A system for 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 system comprising:

a modulator, adapted to modulate a first data signal with a particular orthogonal code to produce the first spread signal having the first bandwidth so that the first spread signal is subsequently orthogonal to the second signal of the second bandwidth;

a transmitter, adapted to transmit the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth;

a comparator, adapted to compare a message length to a predetermined threshold for the message length; and

wherein the transmitter is further adapted to transmit a message using a spread spectrum access channel of the first bandwidth when the message length is less than the predetermined threshold.

4. A system for 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 system comprising:

a modulator, adapted to modulate a first data signal with a particular orthogonal code to produce the first spread signal having the first bandwidth so that the first spread signal is subsequently orthogonal to the second signal of the second bandwidth;

a transmitter, adapted to transmit the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth;

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 second chip rate, or an odd multiple of one-half of the first chip rate to the second chip rate.

5. A method for 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 particular code to produce the first spread signal having the first bandwidth;

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

comparing a message length to a predetermined threshold for the message length; and

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

6. The method of claim 5, further comprising transmitting a pilot signal contemporaneously with transmission of the first spread signal.

7. The method of claim 5, further comprising the step of 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 protocol.

8. The method of claim 5, further comprising the step of adaptively varying a data transmission rate associated with the first spread signal in response to a transmitter power level and a data error rate.

9. The method of claim 5, wherein the first data signal comprises time division multiplexed information from a plurality of users.

10. The method of claim 5, wherein the first data signal has been turbo encoded prior to being modulated by the particular code.

11. The method of claim 5, wherein the modulating is associated with a CDMA protocol.

12. The method of claim 5, wherein the particular code employs a Walsh code.

13. The method of claim 5, 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 second chip rate, or an odd multiple of one-half the ratio of the first chip rate to the second chip rate.

14. A system for 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 system comprising:

a modulator, adapted to modulate a first data signal with a particular code to produce the first spread signal having the first bandwidth;

a transmitter, adapted to transmit the first spread signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth; and

a comparator, adapted to compare a message length to a predetermined threshold for the message length; and

the transmitter further being adapted to transmit a message using a spread spectrum access channel of the first bandwidth when the message length is less than the predetermined threshold.

15. The system of claim 14, wherein the transmitter is further adapted to transmit a pilot signal contemporaneously with transmission of the first spread signal.

16. The system of claim 14, wherein the transmitter is further adapted to transmit 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 protocol.

17. The system of claim 14, wherein the transmitter is further adapted to adaptively vary a data transmission rate associated with the first spread signal in response to a transmitter power level and a data error rate.

18. The system of claim 14, wherein the first data signal comprises time division multiplexed information from a plurality of users.

19. The system of claim 14, wherein the first data signal has been turbo encoded prior to being modulated by the particular code.

20. The system of claim 14, wherein the modulating is associated with a CDMA protocol.

21. The system of claim 14, wherein the particular code employs a Walsh code.

22. The system of claim 14, 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 second chip rate, or an odd multiple of one-half the ratio of the first chip rate to the second chip rate.