Patent ID: 8054905

Claim:
A method, carried out by a mobile station, for determining channel quality information in a high speed packet access communication system with closed loop transmit diversity, the method comprising: determining common pilot channel (CPICH) power and variance in each finger of a rake receiver; adjusting the CPICH power in each finger with a closed loop transmit gain adjustment; combining the adjusted CPICH power and variance in all fingers of the rake receiver; determining a CPICH signal-to-noise ratio; determining a high speed downlink shared channel (HS-DSCH) signal-to-noise ratio from the CPICH signal-to-noise ratio; and mapping the HS-DSCH signal-to-noise ratio to derive the channel quality information, wherein the closed loop transmit gain adjustment for each finger is calculated from complex channel estimates for a first antenna and a second antenna complex antenna weight, wherein: the closed loop transmit gain adjustment ΔG k applied to each finger k is determined from the following: Δ ⁢ ⁢ G k = 1 + 2 ⁢ ⁢ α _ 1 ⁢ I k ⁢ α _ 2 ⁢ I k ⁢ w 2 ⁢ I - α _ 1 ⁢ I k ⁢ α _ 2 ⁢ Q k ⁢ w 2 ⁢ Q + ⁢ α _ 1 ⁢ Q k ⁢ α _ 2 ⁢ Q k ⁢ w 2 ⁢ I - α _ 1 ⁢ Q k ⁢ α _ 2 ⁢ I k ⁢ w 2 ⁢ Q  α _ 1 k  2 +  α _ 2 k  2 where k is a finger index, w is the complex antenna weight, α _ 1 = 1 N ⁢ ∑ n ⁢ α 1 ⁡ ( n ) ⁢ ⁢ and ⁢ ⁢ α _ 2 = 1 N ⁢ ∑ n ⁢ α 2 ⁡ ( n ) ⁢ ⁢ with ⁢ ⁢ N = 5 ; and α 1 k (n) and α 2 k (n) denote complex channel estimates for the first antenna and the second antenna.