Quality of Service-Aware Cross-Layer Optimization in Heterogeneous Multiuser MIMO-OFDM Systems


Wireless local area networks are facing various challenges by modern applications. While the average data rate is the key criterion for file transfers, a maximum delay may not be exceeded for other services like, e.g., video telephony or streaming. In order to guarantee certain quality of service parameters, a strong coupling between layers in the OSI reference model is required.

The multicarrier technique OFDM has proven to be well suited for broadband communications. By using multiple transmit and receive antennas, the quality of transmission can be significantly improved. To this end, many different approaches have been proposed during the last few years. Another interesting aspect is the impact of channel knowledge at the transmitter. It can not only be used to adapt the transmit power and data rate, but also to reduce the signal processing complexity at the mobile devices by suitable precoding. Furthermore, subcarriers can be allocated to different user (OFDMA), or user can be even separated in space (SDMA) instead of using the conventional time division multiple access (TDMA). When selecting the active users, the channel and queue states as well as the application specific requirements must be taken into account.

In this project, the combination of channel and application aware scheduling with different transmission and multiple access schemes is analyzed. Especially the influence of imperfect channel state information at the transmitter is investigated.


Duration: 07/2005 - 12/2009
Funding:German Research Foundation
Partners:Working Group Communication Networks (ComNets), University of Bremen


1 | 2 vor
1 | 2 vor

Involved Staff

Last change on 28.09.2010 by Admin
AIT ieee GOC tzi ith Fachbereich 1
© Department of Communications Engineering - University of BremenImprint / Contact