Wireless Cooperative Network Modeling And Performance Study

Transmissions over wireless channels suffer from multi-path fading and co-channel interference. Diversity has been accepted as an effective technique to combat these deleterious effects. Space, or multiple-antenna diversity combined with other diversity, e.g., time and frequency diversity, leads to a transmission technique that gives dramatic performance gains without incurring the expenditure of transmission time or bandwidth. A new form of single-user space diversity for the cellular environment has been proposed, called "cooperative diversity" or "user cooperation diversity". Terminals in the wireless network each has its own information to transmit, these terminals are all equipped with a single antenna, through sharing their resources to form a "virtual antenna array"(VAA).This type of structure could be viewed as a distributed multiple-input multiple-output (MIMO) system.Several efficient cooperative diversity protocols, including amplify-and-forward (AF) and decode-and-forward (DF) are now widely used. By analyzing, we made comparison among the outage probability and the diversity orders under these protocols. We put forward a new cooperation model of diversity, and analyse the bit error rate performance of the system, finally study the effect of network geometry on the performance of the cooperative diversity system.In all the schemes in this dissertation, the relay terminals are only utilized to assist the transmission from the source to the destination, but do not have their own information to transmit. Actually, terminals in the network could play the role not only of the source terminal but also of the relay terminal. The future research of the cooperation communications, with the consideration of this point, is undoubtedly very promising.