Patent ID: 7411924

Claim:
A method for allocating subchannels and bits to users in a mobile communication system including users requiring services of fixed transmission rates and users requiring services of variable transmission rates, for adaptive modulation, the method comprising the steps of: determining a real number {z, c k } using a Lagrange Multiplier Method, the real number {z, c k } maximizing an objective equation in order to reconstruct a variable rate adaptive problem into a delivery problem; solving the delivery problem through linear programming and allocating subchannels to the users; and allocating bits to the subchannels allocated to the users using a Greedy Algorithm, wherein the Lagrange Multiplier Method is based on max z , c k ⁢ ( z , c k , λ , μ ) = z - λ ⁡ ( ∑ k ∈ U Fixed ⁢ ⁢ f k ⁡ ( c k ) · R M / α k 2 ⁢ c k + ∑ k ∈ U RA ⁢ ⁢ f k ⁡ ( c k ) · z / α k 2 ⁢ c k - P T ) - μ ⁡ ( ∑ k ∈ U Fixed ⁢ ⁢ R M / c k + ∑ k ∈ U RA ⁢ ⁢ z / c k - N ) wherein c k denotes a number of bits to be allocated to a k-th user, R k denotes a k-th user's data rate, P T denotes total allocated power, U Fixed denotes a number of users requiring services of fixed transmission rates, U RA denotes a number of users requiring services of variable transmission rates, ƒ k (c k ) denotes the K-th user's transmission power required for transmission satisfying a desired BER at a reception-side when a channel gain is 1, N denotes a number of the total subchannels, α k denotes a k-th user's channel gain, and λ and μ are parameters.