Patent ID: 8437427

Claim:
A frequency shifter for shifting an arbitrary frequency of an input signal in an arbitrary wireless communication system, comprising: a positive or negative frequency shift controller, used to provide a 1-bit controller PN which controls sign indicators S 1 and S 2 ; a counting up or down counter, receiving a phase increment per sampling instant and the sign indicator S 1 , used to output an integer reference time index, ñ, which is equivalent to a tracking of an accumulated phase increment θ n corresponding to a required phase shift to an arbitrary frequency shift, ±f Δ of the input signal at time instant t=n, wherein f Δ , is a positive number; a cosine function Look-Up-Table (LUT) T 1 and a sine function LUT, T 2 , receiving the reference time index, ñ, used to provide sine and cosine values; and a phase shifter, receiving the sine and cosine values from the sine and cosine function LUTs and the sign indicators S 2 , used to output a complex signal, Ĩ n +j{tilde over (Q)} n , with a frequency shift of the input signal, I n +jQ n ; wherein a mathematical relationship between the input and output of the phase shifter is described as follows: Ĩ n =I n ×T 1 [ñ]−Q n ×S 2 ×T 2 [ñ] {tilde over (Q)} n =Q n ×T 1 [ñ]+I n ×S 2 ×T 2 [ñ], wherein a sampling rate of the frequency shifter is denoted as a positive number, f s , and a ratio 2 ⁢ ⁢ f Δ f s , is a rational number defined in the following mathematical equation: ( 2 ⁢ f Δ f s ) = F M = N ⁡ ( 2 ⁢ M ) + K M = 2 ⁢ N + K M wherein N = ⌊ F 2 ⁢ M ⌋ , 0≦K<2M, M≠0, F, M, N and K are non-negative integers; and a notation, └x┘, is the largest integer which is equal to or smaller than a positive value x.