System for using rapid acquisition spreading codes for spread-spectrum communications

Abstract

A system for rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system, comprises a generator for generating a first long code and a second long code, with each long code having a length of N chips. The first long code is different from the second long code. A transmitter transmits the first long code and the second long code 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 acquisition circuit and a Q acquisition circuit may acquire, in parallel, the first long code and the second long code from the I angle and the Q angle, respectively, of the carrier signal by searching, in parallel, N/2 chips of the first long code and the second long code.

1 . A code division multiple access (CDMA) subscriber unit comprising:
 circuitry configured to establish a connection as part of an access procedure with a network by sending a first CDMA transmission; wherein the first CDMA transmission is derived from first message bits and pilot bits; wherein the first message bits are derived from a message used by the subscriber unit to initiate a connection with the network;   circuitry configured to receive a second CDMA transmission in response to the first CDMA transmission; wherein the second CDMA transmission is derived from second message bits; wherein the second message bits are derived from a message indicating connection setup information.   
   
   
       2 . The CDMA subscriber unit of  claim 1  comprising circuitry configured to send a third CDMA transmission in response to the second CDMA transmission; wherein the third CDMA transmission is derived from third message bits; wherein the third message bits are derived from a message indicating confirmation of the message indicating connection setup information. 
   
   
       3 . The CDMA subscriber unit of  claim 1  further comprising circuitry configured to spread at least the message bits with a first spreading code and to spread at least the pilot bits with a second spreading code; wherein the first and second spreading codes are different spreading codes. 
   
   
       4 . The CDMA subscriber unit of  claim 3  wherein the different spreading codes are orthogonal codes. 
   
   
       5 . The CDMA subscriber unit of  claim 3  wherein the spread message bits correspond to a first channel and the spread pilot bits correspond to a second channel. 
   
   
       6 . The CDMA subscriber unit of  claim 1  wherein the second message bits are recovered from a control channel. 
   
   
       7 . The CDMA subscriber unit of  claim 1  wherein the first CDMA transmission is derived from at least one PN code sequence. 
   
   
       8 . The CDMA subscriber unit of  claim 1  wherein the first CDMA transmission is derived from a complex code sequence; wherein the complex code sequence is derived from at least two PN code sequences. 
   
   
       9 . The CDMA subscriber unit of  claim 1  wherein the first CDMA transmission is a QPSK transmission. 
   
   
       10 . The CDMA subscriber unit of  claim 1  wherein the message indicating connection setup information includes channel assignment information. 
   
   
       11 . The CDMA subscriber unit of  claim 10  wherein the channel assignment information is bearer channel assignment information. 
   
   
       12 . The CDMA subscriber unit of  claim 1  wherein the first message bits are sent over an access channel. 
   
   
       13 . The CDMA subscriber unit of  claim 1  further comprising circuitry configured to send a fourth transmission and circuitry configured to receive an indication that the fourth transmission was received; wherein the first CDMA transmission is transmitted on a condition that the indication is received. 
   
   
       14 . The CDMA subscriber unit of  claim 1  wherein the pilot bits are transmitted synchronously with the message bits. 
   
   
       15 . A method comprising:
 sending by a code division multiple access (CDMA) subscriber unit a first CDMA transmission to establish a connection as part of an access procedure; wherein the first CDMA transmission is derived from first message bits and pilot bits; wherein the first message bits are derived from a message used by the subscriber unit to initiate a connection with the network; and   receiving by the CDMA subscriber unit a second CDMA transmission in response to the first CDMA transmission and deriving a message indicating connection setup information from the second CDMA transmission.   
   
   
       16 . The method of  claim 15  further comprising sending by the CDMA subscriber unit a third CDMA transmission in response to the second CDMA transmission; wherein the third CDMA transmission is derived from second message bits; wherein the second message bits are derived from a message indicating confirmation of the message indicating connection setup information. 
   
   
       17 . The method of  claim 15  further comprising spreading by the CDMA subscriber unit at least the first message bits with a first spreading code and spreading by the CDMA subscriber unit at least the pilot bits with a second spreading code;
 wherein the first and second spreading codes are different spreading codes.   
   
   
       18 . The method of  claim 15  wherein the different spreading codes are orthogonal codes. 
   
   
       19 . The method of  claim 17  wherein the spread message bits correspond to a first channel and the spread pilot bits correspond to a second channel. 
   
   
       20 . The method of  claim 15  wherein the message indicating connection setup information is recovered from a control channel. 
   
   
       21 . The method of  claim 15  wherein the first CDMA transmission is derived from at least one PN code sequence. 
   
   
       22 . The method of  claim 15  wherein the first CDMA transmission is derived from a complex code sequence; wherein the complex code sequence is derived from at least two PN code sequences. 
   
   
       23 . The method of  claim 15  wherein the first CDMA transmission is as a QPSK transmission. 
   
   
       24 . The method of  claim 15  wherein the message indicating connection setup information includes channel assignment information. 
   
   
       25 . The method of  claim 15  wherein the channel assignment information is bearer channel assignment information. 
   
   
       26 . The method of  claim 15  wherein the first message bits are sent over an access channel. 
   
   
       27 . The method of  claim 15  further comprising sending by the CDMA subscriber unit a fourth transmission and receiving by the CDMA subscriber unit an indication that the fourth transmission was received; wherein the first CDMA transmission is transmitted on a condition that the indication is received. 
   
   
       28 . The method of  claim 15  wherein the pilot bits are transmitted synchronously with the message bits.