Research And Simulation Of Channel Capacity And RF Front-end For MIMO

New generation wireless communication needs high speed and reliable data transmission. In order to deliver the desired data rates with high quality of service several difficulties has to be overcome. The wireless channel sets the limit for all transmissions. Time varying multipath fading is one of the major limitations in wireless channels. Diversity in space and time is a common way to defeat the multipath fading. MIMO(Multiple Input Multiple Ourput) technique is presented in this situation. The Space-Time coding is used by MIMO to achieve high speed data transmission in a limited frequency bandwidth with comparably low cost.This article focuses on the research of channel capacity of MIMO system and transmitting module of RF front-end for MIMO mobile terminal, provides a scheme of transmit and receive system based on software simulations. The transmitting module,which is TDD scheme,works at 2.4GHz and consists of a T/R switch,a local oscillator, three transmitter channels and three receiver channels. The transmitter adopt the scheme of direct modulation which consists of several circuits elements such as an I/Q Quadrature Modulator, a Pre-Amplifier,an AGC circuit, a Power Amplifier , a T/R switch and a PLL Frequency Synthesizers, etc. The receiver adopt the scheme of superheterodyne which consists of several circuits elements such as a Low noise amplifier, a Transducer, a surface acoustic wave filter and a Intermediate frequency Modulator, ect. The transmitter and the receiver can be combined with the Baseband Processing Module to build up an MIMO demonstration communication system.First , the channel capacity of MIMO system is discussed, and the channel capacity with antennas selection is calculated. When the order of the transmit matrix is lower than the number of transmit antennas, without reduce the order of the transmit matrix, the selection of base stations and the number of transmit antennas can enhance the channel capacity.Secondly, according to the demands of the MIMO system, the design theories of the RF transmitter and receiver is discussed. The important modules of the transmitter and the receiver are analyzed and simulated.In the end of this article, the deficiencies of the work are pointed out, and the suggestions are made for future research.