| 摘要 |
A long code generator is disclosed that maintains a common long code state between a system with multiple spreading rates, such as a spreading rate equal to the chip rate (1x) and a spreading rate at a multiple of the chip rate (nx), such as three-times the chip rate (3x). An nx long code generator generates n bits for every clock pulse, where the clock operates at the system chip rate. n bits are generated for every clock period by having the long code mask value assume n values for each clock period. Thus, the long code mask value is changed at n times the chip rate, while the shift register is operated at the chip rate. Each of the long codes corresponding to the n long code mask values are multiplexed, for example, using an interlacing technique. The long code generator includes a conventional shift register, AND gate array, modulo-2 adder and clock. In addition, the disclosed long code generator includes a novel long code mask generator that generates n long code masks for each clock period. The long code mask generator operates with a chip rate of n-times the system clock (nx1.2288 MHz). The three long code masks generated for each user must be different from one another, and different from the three long code masks generated for all other users. All the randomness properties necessary for proper CDMA operation are preserved. The present invention applies to both the forward and reverse links for long code generation. Long code state synchronization is maintained between two systems employing different spreading rates, thereby facilitating handoffs without explicit messaging of state information.
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