Rapid acquisition spreading codes for spread-spectrum communications

Abstract

A method and system for rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system. A first long code and a second long code, with each long code having a length of N chips, are generated. The first long code is different from the second long code. The first long code and the second long code are transmitted at a first phase angle and at a second phase angle, respectively, on a carrier signal, over a communications channel using radio waves. The first long code and the second long code may be transmitted at an in-phase (I) angle and at a quadrature-phase (Q) angle, respectively, on the carrier signal. From the communications channel, an I-phase acquisition circuit and a Q-phase acquisition circuit may acquire, in parallel, the first long code and the second long code from the I-phase angle and the Q-phase angle, respectively, of the carrier signal by searching, in parallel, N/2 chips, the first long code and the second long code.

1 . A method for transmitting data from a base station to a subscriber unit in a code division multiple access communication system, the method comprising: 
 producing a code, the code produced by binary addition of a first sequence produced by a first feedback shift register with a second sequence produced by a second feedback shift register;    combining the code with encoded message data, producing spread data; and    transmitting the spread data as a quadrature modulated signal.    
   
   
       2 . The method of clam  1  wherein the quadrature modulated signal is a quadrature phase shift keying signal.  
   
   
       3 . The method of  claim 1  wherein the encoded data is convolutionally encoded data.  
   
   
       4 . The method of  claim 1  further comprising transmitting a spread pilot channel, the spread pilot channel having a code produced by binary addition of a first sequence produced from the first feedback shift register with a second sequence produced by the second feedback shift register.  
   
   
       5 . The method of  claim 1  wherein the first feedback shift register is a linear feedback shift register.  
   
   
       6 . The method of  claim 1  further comprising transmitting paging information on a broadcast channel, the broadcast channel having a code produced by binary addition of a first sequence produced from the first feedback shift register with a second sequence produced by the second feedback shift register.  
   
   
       7 . The method of  claim 1  further comprising transmitting a spread pilot channel, the spread pilot channel produced by a linear feedback shift register circuit, the linear feedback shift register circuit having a total of thirty six stages.  
   
   
       8 . The method of  claim 1  further comprising transmitting paging information on a broadcast channel, the broadcast channel having a code produced by a linear feedback shift register circuit, the linear feedback shift register circuit having a total of thirty six stages.