The Research On The Technicology And Protocols Of Cooperative Diversity In Wireless Network

With the increasing demands of wireless communications in modern times, people are seeking better quality of wireless transmission speed and services. But the improvement of wireless transmission speed and the quality of services are always persecuted by multi-path fading effect of signal transmission. Therefore, many technologies are introduced to resist multi-path fading , among which diversity technique is one of the most effective technologies to resist multi-path fading. Since space diversity does not need to take up extra time and bandwidth resources and can also combine other signal processing forms, it has received wide attention. The most typical diversity technique is MIMO (Multiple Input- Multiple Output), which can turn the factors of multi-path in traditional communications systems to those benefits to users' communication performance. It has remarkable advantages in resisting multi-path fading and improving transmission speed and quality. Its Spatial Transmit Diversity Technique (STD) has become standard protocol of 3GPP WCDMA. However, due to the physical conditions of mobile terminal, such as terminal size, power cost, settings of multiple antenna, etc. the application of spatial diversity techniques is limited. There out, people was enlightened from relay channel, the conception of Cooperative Diversity was put forward by Sendonaris. Firstly, this paper introduced the diversity technique which is widely used in the mobile communication system。At the same time, emphasized on the spatial diversity techniques which involved in my project, the performance of the diversity system and non-diversity system based on analyzing and comparing all kinds of index and effect was discussed.Secondly, this paper introduced the concept of cooperation diversity. To solve this limitation that the spatial diversity generally requires more than one separated antenna at the mobile terminal, while unfortunately which is impractical in wireless cellular system due to the size or hardware complexity of the mobile terminal, a new form of spatial diversity called cooperation diversity was proposed. Compared to the spatial multiple-input multiple-output (MIMO) system, the cooperation diversity enables single-antenna mobiles in a multi-user environment to share their antennas so that each mobile is served by a virtual multiple-antenna transmitter receiver.Again this paper presented an overview of the developments in this field, and then discussed the effect and performance improvement have made so far. At the same-time introduced three methods of cooperative diversity: Amplify and forward (AF), decode and forward (DF), coded cooperation (CC) and then made a brief note on the Program of AF and CC.Finally, this paper discussed modularize of cooperative diversity based on the three methods mentioned above. Meanwhile sub-modules were also designed, including convolutional coding and Viterbi decoding, diversity receive, channels, max ratio combination and so on. The performance difference between diversity and non-diversity in Additive White Gaussian Noise(AWGN) channel, static channel, fast fading channel by mass emulation data was analyzed...