DMT调制（国外英文资料）.docVIP

DMT调制（国外英文资料） DMT and convolution encoding are used in DSLS Zhong xiaoliang, a friendly citizen of the city of pendleton (central China normal university physics department wuhan 430079) 【 abstract 】 to discuss the combination of discrete audio modulation and grid coding modulation mode in a DSL, the application of discrete audio more DMT modulation (1) is a multi-carrier modulation technique, will transmit data according to each subband signal-to-noise ratio according to the assigned subband, make each subband element width greater than the multipath delay. The combination of modulation and error correction can make the error rate much lower, which is a higher bandwidth utilization modulation.  keywords: ADSL discrete audio grid coding Euclidean distance [3] [2] of the discrete Fourier transform/inverse transformation 1 lead it  with the continuous development of Internet technology, the speed of data transmission, more and more high quality requirements, in the current in order to effectively use of existing resources, telephone line and put forward the DSL (digital subscriber line) [1], the concept of using more than voice frequency band (4 k ~ 1.1 MHz) for high speed digital signal modulation, in accordance with the Δ f = 4.3125 kHz divided into subband, because Δ f just is the width of the audio, so named discrete more audio, DMT modulation is based on discrete Fourier transform to modem parallel data. With the continuous improvement of VL SI and digital signal processing (DSP) technology, real-time DMT modulation has been implemented using FFT. But before demodulation system, error correction coding and modulation is designed and implemented independently, decoding and demodulation, such demodulator in the received signal is independent of signal hard, hard decision to give decoder decoding, this hard decision will lead to the receiver the unrecoverable loss of information, to solve the problem of method is to adopt soft decision decoding at the receiving en