Patent ID: 7555074

Claim:
A method of estimating an interference level of a signal received in a receiver, comprising the steps of: detecting an interference level of the received signal; determining whether the detected interference level is low; and if the detected interference level is low, estimating the interference level by at least one of estimating in only a radial direction and de-rotating the received signal before estimating the interference level; wherein the radial direction is parallel to a real coordinate axis, and the interference level is estimated in only a radial direction according to I i CPICH = 2 · 1 N C - 1 ⁢ ∑ k = 1 N C ⁢ Re ⁡ ( ⅇ - j · φ ⁡ ( y CPICH , i ⁡ ( k ) - h ^ CPICH , i ⁢ u k CPICH ) ) 2 ⁢ ⁢ and I i DPCH = SF C SF D ⁢ I i CPICH ⁢ where I i DPCH is an estimate of an interference level on a first channel DPCH for a receiver tap i, I i CPICH is an estimate of an interference level on a second channel CPICH for the tap i, k is a time index, SF C is a spreading factor for the second channel, SF D is a spreading factor for the first channel, N C is a number of symbols per slot on the second channel, φ is an angle of ĥ CPICH,i , y CPICH,i (k) is a de-spread pilot symbol of the second channel at time instant k for tap i, ĥ CPICH,i is a channel estimate of the second channel for tap i, and u k CPICH is a pilot symbol of the second channel at time instant k.