For cellular mobile communications networks, it is difficult to provide high data rates throughout a cell, particularly at the rand areas. One way to solve this problem is the reduction of the range of the cell, which can lead to considerable additional costs. The cooperative relay-concept allows an effective and cost-efficient alternative to insure high data rate at the cell rand. Relays can be realized by fixed stations as well as other mobile subscribers. They have the advantage that they could be neither the intelligence of a base station nor with connections to the backbone networks, but still can contribute for the cooperative communication. In addition, the relaying technology can reduce the strong path loss and allow the use of spatial diversity. The interpretation of several relays as a virtual antenna arrays allows the utilization of MIMO technology without requiring physical multiple antenna at the device.

In this project we study and analyse the static and adaptive relaying protocol in combination with distributed Space-Time codes. In particular, the use of ARQ (Automatic Repeat Request) for the adaptive controls of the transmission methods will be evaluated. For the various methods information-theoretical investigations of the networks in terms of recoverable data rate and the probability of errors will be done. Improvements for the implementation and new approaches for cooperative communication systems will be investigated. Based on the analytical studies, the strategies to optimize the resources allocation in terms of bandwidth, transmission power and scheduling under the consideration of various criteria such as end-to-end capacity, outage probability, or error rate can be developed. Through the efficient use of the resources within the network, the transmission power will be reduced while satisfying the required quality of service. The analytical statements based on exemplary simulations of cooperative multi-hop systems will be verified.

 

Details

Duration:	05/2008 - 04/2011
Funding:	Central Research Funding, University of Bremen

1 | 2