Patent ID: 8213376

Claim:
An OFDMA power allocation method for managing power in a wireless communication system having a base station and a plurality of wireless users, the system implementing scalable orthogonal frequency division multiple access with quality of service proportional rate constraints, the method comprising the steps of: distributing N sub-channels among K users of the wireless communications system; receiving wireless requests at the base station for access to the wireless communications from the users; assessing power gain relative to noise for each sub-channel allocated to each user; iteratively computing sub-channel power allocations for each user based on the proportional rate constraints and the channel power gain information, thereby strictly satisfying the proportional rate constraints; and transmitting the power allocations to each of the users requesting access; wherein, said step of iteratively computing the sub-channel power allocations for each user comprises the steps of: inputting N number of sub-channels, K number of users, and channel power gains H k,n (k=1, 2, . . . , K, and n=1, 2, . . . , N); inputting rate constraints γ k for (k=1, 2, . . . , K); inputting total power P total ; inputting Ω k 's subchannel allocation sets; calculating V k constants using the equation V k = ∑ n = 2 N k ⁢ H k , n - H k , 1 H k , n ⁢ H k , 1 ; calculating the W k constants using the equation W k = ( ∏ n = 2 N k ⁢ H k , n H k , 1 ) 1 N k ; determining whether the sum of the calculated V k constants is less than or equal to the total power P total , and if this is not the case then performing the steps of: (i) selecting a set of Ω k that corresponds to the largest V k (ii) dropping the weakest channel from Ω k , thereby updating the sub-channel frequency allocation; (iii) recalculating the V k and W k ; (iv) repeating (i) through (iii) until the sum of V k 's is less or equal to P total ; otherwise, if the sum of the calculated V k constants is less than or equal to the total power P total , then performing the steps of: selecting a user index such that a corresponding ( W i ) N i γ i is greater than or equal to ( W k ) N k γ k for all k≠i and k=1, 2, . . . , K; assigning the value 1 to an X i,Low and assigning the value 1+H i,l (P total −V k )|N i to an X i,High ; determining whether the equation ∑ k = 1 K ⁢ [ ( N k H k , 1 ) ⁢ ( ( X i ⁢ W i ) N i ⁢ γ k γ i ⁢ N k W k - 1 ) + V k ] - P total = 0 changes sign and recalculating the Ω k , V k , W k and P total if the sign has not changed, otherwise solving ∑ k = 1 K ⁢ [ ( N k H k , 1 ⁢ ) ⁢ ( ( X i ⁢ W i ) N i ⁢ γ k γ i ⁢ N k W k - 1 ) + V k ] - P total = 0 for X i ; computing all X k for k≠i and k=1, 2, . . . , K using the equation X k = ( X i ⁢ W i ) N i ⁢ γ k γ i ⁢ N k W k ; computing P k,1 for all k=1, 2, . . . , K, using the equation p k , 1 = ( P k , total - V k ) N k ; and computing p k,n for all k=1, 2, . . . , K, and n ε Ω k using the equation p k , n = p k , 1 + H k , n - H k , 1 H k , n ⁢ H k , 1 .