Research On The Method Of Twisted-pair Hign-speed Transmission Based On MIMO

Ethernet is the most common standard of LAN communication protocol, and in Ethernet standard, unshielded twisted pair is widely used as the transmission medium, such as Ethernet, Fast Ethernet, Gigabit Ethernet and 10 Gigabit networks all define standard-based on unshielded twisted pair. Because of its cheap, easy wiring works, etc., unshielded twisted pair becomes the most widely used Ethernet transmission media. But unshielded twisted pair suffers the far-end crosstalk interference, the value of far-end crosstalk increases with frequency, and it is difficult to eliminate. So, far-end crosstalk is a major factor which inhibits improvement of the speed rate of unshielded twisted pair system.In fact, the far-end crosstalk which is from the remote transmitter contains useful information transmitted by other signal lines, the system can make use of it, take MIMO technology into unshielded twisted pair transmission system, the far-end crosstalk and signal suffering insertion loss can form a 4 × 4MIMO model.Using MIMO technology can improve the capacity of the system. Meanwhile, OFDM technology divides the entire work bandwidth into multiple sub-channels, effectively improving the spectrum efficiency, when the system allocates each of the OFDM subcarriers’ bit and power,we can make use of the bit and power allocation algorithm proposed in this paper, which is in close to the optimal allocation algorithm on the basis of performance, significantly reduces the computational complexity. The main work of the paper is as follows:Firstly MIMO and OFDM technology are briefly described, we analyze the capacity of MIMO, the three space-time coding techniques: space time block code, space time trellis code and layered space time code; and then briefly introduce the mathematical model of OFDM, its implementation and several key technologies, such as synchronization, channel estimation techniques etc. At last we introduce the MIMO-OFDM system.Secondly, adaptive bit and power allocation algorithm is introduced, the paper analyzes its theoretical basis, optimization criteria, and then describes three typical adaptive algorithm.At last we show a bit and power allocation algorithm which is proposed by this paper.Finally, with m language of Matlab, this paper designs a high-speed unshielded twisted pair line simulation system which is based on MIMO. The workflow of simulation system, the function of each module are described, and finally it shows the simulation results. Simulation results show that using MIMO technology which can change far-end crosstalk into useful signal to overcome unquenchable far-end crosstalk problem in the traditional systems, can significantly improve system capacity.