34 Another algorithm that uses the MA approach is presented in . In this paper, the authors propose a block-wise subcarrier allocation algorithm that is shown in Figure 16. N subcarriers are divided into M blocks and each block has n adjacent subcarriers. The bandwidth of each block of subcarriers is smaller than the coherence bandwidth of the channel and hence the channel is flat-fading for each block. Also, the subcarriers in a block are assumed to be highly correlated to each other. Each user is assigned a certain number of blocks based on his or her minimum data rate constraint. The authors define the problem as: P = min P m m = 1 M ∑ with the constraints P ≤ P o and r k ≥ R k …(E26) P o is the total power constraint and R k is the minimum required rate for user k . r k is the allocated rate of user k and is given by: r k = f km F P m h k 2 ( k ) σ n 2 ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ m = 1 M ∑ …(E27) To solve the problem, the authors first calculate and assign C k ( ∀ k ∈ [1,
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