The Design Of Microwave Transmission System Indoor Unit Based On Cross-polarization Interference Cancellation

With the rapid development of technology, communication technology is also developing rapidly. The most obvious feature in the progress of communication technology is that, the unit used to measure the communication transmission rate has rose from Kbps to Mbps, Gbps and even to Tbps. Progresses in communication technology also reflect in the change in transmission mode, from cable to optical fiber, from wired communication to wireless communication, every changes can bring people new communication experience. In addition, the business type of communication is also increasing, such as the E1 and STM-1 that only apply to voice communication,and later the Ethernet packet services has shown up. Microwave transmission system is the product of communication technology progress, the system can multiplex and modulate the E1,STM-1 and packet data service to microwave wireless transmission link.Microwave transmission system set up fast and easy using. Microwave is similar to visible light, which can communicate ignoring the complex terrain, and the transmission distance can reach up to tens of kilometers. These devices usually used for rapid reconstruction of communication network destroyed by natural disasters, and communications between straits and cliffs. The disadvantage of microwave communication is the low utilization rate of the spectrum, which leads to low information transmission rate. In order to improve the information transmission rate, some transmission technologies such as the quadrature amplitude modulation and co-channel cross-polarization have been used.This article introduces the design of Indoor Unite which supports the XPIC(cross-polarization interference cancellation) function. There are four parts:1, Theoretical studies and simulation. Introduce the XPIC and simulate the algorithms with MATLAB; describe the modulation and demodulation involves in this article and analyze the performance.2, Hardware design. Introduce the design of power topology and master tray, business tray and modulation-demodulation tray. The innovation in the design is that, IDU is designed with multi-clock, the signals of business recovery clock, local clock and digital synchronization network clock are sent to the main control tray. The main control tray select one clock signal by priority as the maser clock, and send the clock to each tray by clock distributor, and then realize the clock synchronization of microwave communication system. This section also introduces the practical application of EMC in IDU.3, Software design. Design the monitoring software of IDU with "top-down" approach.4, Test results. The hardware and software test results show that IDU perfectly reach the expectation indexes.