The Low Power Research Of Adaptive Receiver Of OFDM Digital Base-band

With more and more wireless devices have been used in our life, people are increasingly demanding for multimedia services. Transmission of multimedia services requires a certain bandwidth guarantee, but the traditional wireless network cannot do very well in serving multimedia services. OFDM technology is a promising modulation technology in next generation communication due to its higher spectrum efficiency and good anti-multipath performance. In the fourth generation mobile communication standard, OFDM will be used as the modulation technology in the physical layer to provide higher transmission quality. As a hand-held wireless device, commonly used battery-powered, power consumption is the key to its success. In this paper, low power consumption of the OFDM digital baseband receiver was studied, and some parts of the receiver which have high power consumption are optimized.First, the basic structure of the OFDM digital baseband receiver and the power ratio of all the parts in the receiver are analyzed. The analysis showed that the channel estimator and the channel decoder (Viterbi decoder) takes up 70% to 80 % of the entire wireless digital baseband transceiver power consumption, so if you can optimize the design of the two parts, you will greatly reduce the power consumption of wireless handsets.Secondly, several channel estimation algorithm are researched. Based on the traditional algorithm, computationally efficient channel estimation is proposed. Both the pilots and training sequences are used for estimation. The state space model is modified and the Kalman filter algorithm is simplified. Matlab7.0 is used for the system modeling and simulation. Simulation results show that the proposed method have a lower complexity, and the performance of the proposed method is better than the traditional ones. And then, the Viterbi Decoder is used in the system for channel decoding, and the performance vs. tracing depth is simulated in different coding rate and modulation method (BPSK (1/2, 3/4), QPSK (1/2, 3/4), 16QAM (1/2, 3/4), 64QAM (2/3, 3/4)). Based on the simulation result, an adaptive Viterbi Decoder is proposed. The Viterbi decoder can change trace depth automatically by the design of a reconfigurable SMU (survivor path memory unit). In this paper we also simplify the branch metric arithmetic, so as to decrease the complexity of the BMU (branch metric unit) and the ACSU (add-compare-select unit).Most of the researches are only referenced on the algorithms. However, few of them implemented the algorithms, especially in the channel estimator. In this paper, the hardware design of the channel estimator and Viterbi decoder are proposed, and the area and power consumption are get through the EDA tool ISE and Designer Compiler. Synthetically results show that the algorithms proposed in this paper have the best performance and lowest area and power consumption.