Noise variance estimation method and apparatus of random access channel

The invention provides a noise variance estimation method and apparatus of a random access channel. The method includes the steps: calculating a power delay distribution sequence of a lead code, averaging the sequence, obtaining a noise decision threshold, selecting in the sequence a point the noise of which is smaller than the noise decision threshold, performing noise variance estimation on the selected point, and obtaining a first noise variance estimated value; calculating a peak value decision threshold according to the first noise variance estimated value, and carrying out peak value decision; obtaining the number of detected users according to a peak value decision result; and determining whether the number of detected users is higher than a preset threshold of users, selecting in the power delay distribution sequence a pre-specified data segment and taking the data segment as a noise sequence if the number of detected users is higher than the preset threshold of users, performing noise variance estimation on the noise sequence to obtain and output a second noise variance estimated value, otherwise, outputting the first noise variance estimated value. According to the invention, the random access success rate can be increased.