In this paper, we investigate adaptive resource allocation strategy for downlink multi-input-multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. We design a transmit scheme as a concatenation of dynamic sub-carriers and bit assignment, adaptive modulation and beam-forming. Our adaptive goal is margin adaptive optimization, which minimize the total transmission power subject to a target BER performance constraint on each sub-carrier, while meeting a constant bit rate. By use of Rayleigh fading model assumption, we introduce a new concept: the channel feedback coefficient, so as to compensate the error inducted by feedback channel. Simulation results show that the proposed resource allocation scheme outperforms the multi-user MIMO-OFDM with static allocation technique, and can lessen the performance loss caused by channel state information feedback error.
Proc. SPIE. 6022, Network Architectures, Management, and Applications III
KEYWORDS: Signal to noise ratio, Optical fibers, Optical design, Radio optics, Modulation, Receivers, Adaptive optics, Computer simulations, Orthogonal frequency division multiplexing, Signal detection
The use of radio over fiber to provide radio access has a number of advantages including the ability to deploy small, low-cost remote antenna units and ease of upgrade. And due to the great potential for increasing the capacity and quality of service, the combination of Orthogonal Frequency Division Multiplexing (OFDM) modulation and the sub-carrier multiplexed optical transmission is one of the best solutions for the future millimeter-wave mobile communication. And
this makes the optimum utility of valuable radio resources essential. This paper devises a cross-layer adaptive algorithm for optical-wireless OFDM system, which takes into consideration not only transmission power limitation in the physical layer, but also traffic scheduling and user fairness at the data-link layer. According to proportional fairness principle and water-pouring theorem, we put forward the complete description of this cross-layer adaptive downlink transmission 6-step algorithm. Simulation results show that the proposed cross-layer algorithm outperforms the mere physical layer adaptive algorithm markedly. The novel scheme is able to improve performance of the packet success rate per time chip and average packet delay, support added active users.