Decreasing transmit power by adaptive loading for ultra high-data-rate OFDM system

In this paper, we focus on developing an adaptive bit and power loading algorithm for DPC-OF/TDMA (dynamic parameter controlled orthogonal frequency and time division multiple access) system, which is actually an OFDM system supporting data transmission beyond 100 Mbps. The proposed adaptive loading algorithm is used in each subband of DPC-OF/TDMA system and aims at minimizing the transmit power under the conditions that the stable data rate and error probability are maintained. This is in responding to the requirement of DPC-OF/TDMA which should avoid generating strong interferences to other subbands, users and systems. On the other hand, this feature helps to prolong the battery lifespan. Based on the iterative mechanism, the proposed adaptive loading algorithm loads the bits and power to the subcarrier at which there is a modulation mode demanding the minimum average incremental power per incremental bit to guarantee the pre-designated bit error rate (BER). The performance investigations show the proposed algorithm can greatly decrease the transmit power and its dynamic range under the conditions that the data rate and BER are maintained to the target values.