Suboptimal Greedy Power Allocation Schemes for Discrete Bit Loading

Algorithm 2

g-GPA algorithm for subchannels in the 𝑘th QAM group 𝐺_𝑘.

(1)  ∀𝑖∈G_𝑘, calculate the upgrade power 𝑃^up_𝑖=𝛾^QAM_𝑘+1−𝛾^QAM_𝑘/CNR_𝑖

(2) Initiate 𝑏^g_𝑖,𝑘=𝑏^𝑢_𝑖,𝑘 in (10) and 𝑃^LO_𝑘=𝑃^ex_𝑘 in (11)

  while   𝑃^LO_𝑘≥min(𝑃^up_𝑖)

(3)      𝑗=argmin_𝑖∈G𝑘(𝑃^up_𝑖)

(4)      𝑃^LO_𝑘=𝑃^LO_𝑘−𝑃^up_𝑗

      if   𝑘=0

(5)       𝑏^g_𝑗,𝑘=log₂𝑀₁, 𝑃^up_𝑗=+∞

      else

(6)       𝑏^g_𝑗,𝑘=𝑏^g_𝑗,𝑘+log₂𝑀_𝑘+1𝑀_𝑘, 𝑃^up_𝑗=+∞

      end

  end

(7) Evaluate 𝐵^g_𝑘=∑_{𝑖∈𝐺𝑘}𝑏^g_𝑖,𝑘 and 𝑃^LO_𝑘