An enhanced multimode power loading algorithm applicable to large dimensional OFDM systems

Multi-mode power loading is an attractive power loading technique since it avoids iterative procedures and periodic updates of a threshold value in order to find the best power loading configuration. Simultaneously, multi-mode power loading achieves comparable spectral efficiency to optimal waterfilling with full channel state information (CSI) using only N feedback bits, where N is the number of subcarriers. The requirement of 2^N - 1 brute-force searches, however, makes multi-mode power loading infeasible for large N. This paper proposes a new power loading technique to circumvent this limit of multi-mode power loading. Our analysis and numerical results show the proposed technique achieves the same spectral efficiency as multi-mode power loading only using N searches, thus working well even for large N.