Energy Efficient Design for OFDM-Based Underlay Cognitive Radio Networks

Algorithm 1

Bisection search aided algorithm (BSAA) for Problem P4.

Step  1. Initialization, 𝜇_opt←0.

Step  2. Calculate the optimal water level 𝜇_min and 𝜇_max,

and set 𝜇_low←𝜇_min and 𝜇_high←𝜇_max.

Step  3. Set 𝜇_mid←(1/2)(𝜇_low+𝜇_high).

Step  4. If its derivative 𝑑𝑈/𝑑𝜇∣_𝜇=𝜇mid>0, then

𝜇_low←𝜇_mid, else 𝜇_high←𝜇_mid.

Step  5. Repeat Step  4 until 𝜇_high−𝜇_low≤𝜉 where 𝜉

(e.g. 𝜉 = 0.001) is a small positive constant to control the

convergence accuracy.

Step  6. Finish, the optimal water level solution is

𝜇_opt←𝜇_mid.