A pre-estimated resource allocation algorithm based on cognitive OFDM for multi-user

Multi-user cognitive orthogonal frequency division multiplexing (C-OFDM) is an extremely promising technique for achieving high transmission capacity in the next generation cellular and wireless local area network (WLAN) systems with limited spectrum resources. And a proportional fairness subcarriers allocation algorithm based on the margin adaptive (MA) principle is used to meet the rate fairness between users. This paper presents a new bit and power allocation scheme for C-OFDM systems based on the margin adaptive (MA) principle in which the overall transmission power is minimized by constraining the fixed data rate and bit error rate. Simulation results show that the proposed algorithm is superior to the traditional algorithm, while reducing the computational complexity from exponential to linear in the number of sub-carriers.