1、南京航空航天大学硕士学位论文OFDM 的动态子载波功率分配算法研究姓名：张弛申请学位级别：硕士专业：通信与信息系统指导教师：许宗泽20061201i OFDMOFDMOFDMMatlab OFDM ii ABSTRACT OFDM (Orthogonal Frequency Division Multiplexing) has outstanding advantages because that it could utilize frequency resource sufficiently and robust against channel delay spread. It is sui
2、table for high speed and broadband wireless communication. It modulates the signals to subcarriers which are orthogonal and increase the time for sending signals, so it can reduce the effect of inter-symbol interference (ISI) effectively. But OFDM is sensitive to the frequency offset because the ort
3、hogonality between subcarriers resulting inter-carrier interference (ICI) which gives rise to an irreducible error floor of the systems bit error rate (BER). This paper mainly researches on dynamic resource allocation in OFDM systems. In broadband OFDM system over mobile fading channels, which have
4、different channel capacity, if a fixed modulation scheme is applied to all subcarriers, the whole systems capacity and the transmitted power have not been full used. In this paper, various dynamic subcarrier, bit and power allocation schemes are discussed. This algorithm distributes the information
5、bits, the signal constellations and transmitting power adaptively to different subcarriers according to channel instantaneous attenuations to satisfy average power and BER constraints. Besides, a dynamic subcarrier and power allocation scheme based on embedded constellation is proposed in this paper
6、. With the goal of minimizing the overall transmit power while ensuring the fulfillment of each users transmission rate and QoS requirement, embedded constellation based algorithm allows that a subcarrier could be shared by multiple users. It can also achieve high performance with low compute comple
7、xity by theory and Matlab simulations. Key Words: OFDM, BER, Adaptive, Embedded Constellation, Dynamic Subcarrier and Power Allocation, Water-filling Policy v 2.1 () f () S .12 2.2 () t ()S .12 2.3 .13 2.4 .14 2.5 OFDM-.15 2.6 OFDM.16 2.7 OFDM4.17 2.8 OFDM.18 2.9 OFDM.18 2.10 OFDM.19 2.11 OFDM-.23 3
8、.1 OFDM.27 3.2 .30 3.3 BER.35 4.1 OFDM.36 4.2 .42 4.3 .45 4.4 .45 5.1 QPSK.47 5.2 16QAM32QAM.48 5.3 64QAM.49 5.4 PSKQAM.50 5.5 .51 5.6 32QAM.52 5.7 4K = .55 5.8 310BER = .55 5.9 310BER = .56 OFDM vi 2.1 .20 2.2 .21 3.1 .32 3.2 .35 4.1 .46 vii AA Adaptive Allocation Algorithm ABA Adaptive Bit Allocat
9、ion ADSL Asymmetric Digital Subscriber Line AMPS Advanced Mobile-Phone System AWGN Additive White Gaussian Noise BER Bit Error Rate CDMA Code-Division Multiple Access - CP Cyclic Prefix - DAB Digital Audio Broadcasting DCA Dynamic Channel Assignment DFT Discrete Fourier Transform DMT Discrete Multi-
10、Tone Modulation DS Doppler Shift DSP Digital Signal Processing DVB Digital Vision Broadcasting EBA Equal Bit Allocation FCA Fixed Channel Assignment FDMA Frequency Division Multiple Access FEC Forward Error Correction FFT Fast Fourier Transform FSF Frequency Selective Fading Channel GI Guard Interva
11、l GSM Global System for Mobile HDTV High-Definition Television IBCN International Broadband Communication Network ICI Inter-Carrier Interference IDFT Inverse Discrete Fourier Transform IFFT Inverse Fast Fourier Transform ISI Inter-Symbol Interference MCM Multi-Carrier Modulation MIMO Multiple Input
12、Multiple Output - , () 1 OFDMOFDM 1.1 1897-2070 -1 11G2080800MHzAMPSTACSC-450 22G208090GSM-CDMAIS-54800MHz-1900MHz 33G-2GHz144kbit/s384kbit/s2Mbit/scdma2000WCDMATD-SCDMA OFDM 2 21,2 Internet- -4G1,3 1UMTS2Mbit/s100Mbit/s 2WLANB-ISDNATMIBCN 3)150Mbit/s 4G3G3G2Mbit/s4GIP 4G4GMCMMCMNN-1/N-NmaxMCMN-3 OFDMOFDMOFDM- 1.2 OFDM 1.2.1 OFDM OFDM2050460-19701OFDMOFDMOFDM1971WeinsteinEbertIDFTDFTOFDM1,5DFT OFDMOFDMDFTOFDM-2080OFDMIFFTFFT-
