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

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.

What is claimed is:  
     
         1 . A method of transmitting a first spreaded 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 spreaded signal having the first bandwidth so that the first spreaded signal is substantially orthogonal to the second signal of the second bandwidth; and,    transmitting the first spreaded signal and the second signal simultaneously so that the first bandwidth overlays the second bandwidth.    
     
     
         2 . The method of  claim 1 , further comprising the step of transmitting a pilot signal contemporaneously with transmission of the first spreaded signal.  
     
     
         3 . The method of  claim 1 , 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.  
     
     
         4 . The method of  claim 1 , further comprising the step of adaptively varying a data transmission rate associated with the first spreaded signal in response to a transmitter power level and a data error rate.  
     
     
         5 . The method of  claim 1 , further comprising the step of 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 length is less than the predefined threshold.  
     
     
         6 . The method of  claim 1 , wherein the first data signal comprises time division multiplexed information from a plurality of users.  
     
     
         7 . The method of  claim 1 , wherein the particular orthogonal code is associated with turbo coding.  
     
     
         8 . The method of  claim 1 , wherein the modulating step is associated with a CDMA protocol.  
     
     
         9 . The method of  claim 1 , wherein the particular orthogonal code is a Walsh code.  
     
     
         10 . The method of  claim 1 , wherein a first carrier frequency associated with the first spreaded 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 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.