METHOD AND DEVICE FOR CAPTURING PSEUDO NOISE IN CODE DIVISION MULTIPLE ACCESS MOBILE COMMUNICATION SYSTEM

摘要

PURPOSE: A method for capturing a pseudo noise(PN) in a code division multiple access mobile(CDMA) communication system is provided to shift a phase of a mobile station PN sequence for calculating each detecting energy corresponding to each phase shift, to accumulate the detecting energies to be stored according to hypotheses, so as to make time sections of the detecting energies have time differences to reduce an average PN capturing time without lowering a PN capturing probability even when a receiving signal falls into a fading. CONSTITUTION: A controller initializes a search window number 'k'(S805). The controller initializes each hypothesis number 'i'(S810). The controller initializes each memory area 'Z(i)' according to each hypothesis of an accumulation storage. The controller shifts a phase of a mobile station pseudo-noise(PN) sequence relating to base station PN sequences successively inputted in real time, and calculates partial detection energies relating to the hypotheses(i=1-W) corresponding to the phase shift(S815). The controller accumulates the partial detection energies in the accumulation storage according to the hypotheses, and stores the accumulated partial detection energies(S820). The controller checks whether a present 'i' is a last hypothesis within a search window(S825). If not, the controller controls a PN generator to shift the phase of the mobile station PN sequence to a corresponding direction(S830). The controller reperforms controlling operations of the steps 'S815' and 'S820'. If the present 'i' is the last hypothesis, the controller checks whether the partial detection energies are calculated as much as the number of times relating to each hypothesis(S835). If not, the controller controls the PN generator to shift the phase of the mobile station PN sequence to a direction opposite to the phase shift of the step 'S830', and moves to a first hypothesis(S840). If the partial detection energies are calculated as much as the number of times relating to each hypothesis, the controller controls a peak detector to detect a biggest energy(S845). The controller compares the biggest energy with a critical value(S850). If the biggest energy is smaller than the critical value, the controller controls the PN generator to shift the phase of the mobile station PN sequence to the corresponding direction. The controller reperforms controlling operations of the steps 'S810' and 'S850' relating to a next search window 'k++'.