The Research Of Channel Estimation Algorithms For Wireless Communication System

Wireless communication appears after the wired communications, and has become the common concern and one of the most active areas in the IT industry and the global communication field, From the scientific point of view, it's a legend in the field of the engineering; It's possible for the people to communicate with each other at anytime and anywhere in the world. With the market demand enlargement, people have been tied up tightly by the wireless Internet. From the 20th century, mobile communication technology has been developed more and more mature. The wireless technology has experienced two stages, that is, simulation technology and narrow-band digital technology. Currently, the third generation cellular systems based on wideband CDMA has also been widely used and promoted. The typical systems of the first generation are:the European's TACS (total access communications system) and the United States's AMPS (advanced analog telephone system); the second generation application includes the European's GSM (Global System for Mobile Communications) and the United States's IS-136 (using the combination of FDMA and TDMA technologies). However, the most important focus for the mobile communication technology is concerning the voice communication. With the application of wireless terminals increasing, these "slim" devices must support a very wide range of applications. In addition, the wireless network also needs to locate the required user's position from a variety of mobile devices.This paper describes the basic structure of wireless communication systems,wireless channel's model,and the utilizations of the Spectrum. Based on these basic theoretical knowledge and key technologies, the paper studies wireless channel detection algorithm. In real multi-path wireless channel, the transmitted sequence is disturbed by serious inter-symbol-interference. So, we need to detect the most likely sequence from the received symbol sequence. At present, the ML (maximum likelihood criteria) is usually used at the receiver, and the VA (Viterbi algorithm) is the core of the Criterion, which is used for sequence detection. It is similar with the convolutional decoder, the algorithm is to be compared paragraph by paragraph in the grid map, and select the most likely path decision. But the direct comparison paragraph by paragraph will generate huge consumption for the storage resources of the system, so we improve the Viterbi algorithm, and make it to be iterative type of algorithm, so that the processing speed can be improved and the system resources can be saved. This paper also researches the improved channel estimation based on RLS algorithm, and simulates the performance of the channel estimation based on mean square error criterion.