网络编码（MATLAB源代码）

To whom it may concerned, In 'test' folder, MATLAB codes for network coding are provided. The following are introduction to most important files. 1-Main.m Main.m is start of all codes. Type 'Main' in MALTAB command window, you run this project and get final results. Two alternative modes are available through variable 'multiuser_flag'. Under both conditions, analog speach signal is converted to bits sequence by function 'LPC_encoder' at first. Secondly, bits sequence go through function 'Network', which simulate 'two-nodes' network or 'three-nodes' network. Finally, bit sequence at receiver are converted back to analog speach signal. 2-Network.m In Nework.m, function 'Simulate' is used to realize data transmission between two nodes. For 'two-nodes' mode, function 'Simulate' is applied once. For 'three-nodes' mode, function 'Simulate' is applied four times. 3-Simulate.m In Simuate.m, data transmission between two nodes are implemented. First of all, number of superframe needed in total is evaluated and assigned to 'nr_frame'. Secondly, data are separated into various data blocks and are inserted into different superframe. Each superframe contains guard bits at both head and tail, training sequence for synchronization and data block as well as estimate bits for channel estimation. For each super frame, bits sequence go through transmitter, channel and receiver.Transmitter and receiver are done by Transmitter.m Receiver.m file respectively. Four channel are available: Ideal, AWGN, Rayleigh fading and Rayleigh fading under AWGN channel. 4-Transmitter.m Transmitter.m acts as transmitter in wireless communications. Bits sequence are mapped into complex values under scheme QPSK or QAM, which becomes symbol sequence. Then this symbol sequence are convolved with pusle and upsampled on purpose of anti-Inter Symbol Interference. After up-conversion or carrier modulation, these symbol sequence are sented to channel. 5-Receiver.m Receiver.m acts as receiver in wireless communicaitons. In the beginning, down conversion is applied. Signals are transferred to base-band from pass-band. After low-pass filter, matched filter, synchronization, phase estimation, channel estimation and detection, these symbols are converted back to bits.