Research Topic

Multi-User Networks with Outdated Channel State Information

Two-user Broadcast Channel with delayed CSIT

In communication systems the channel state information (CSI) is usually obtained by receivers by transmitting pilot symbols from the transmitter to the receivers. The receivers then feed back the obtained information back to the transmitters, so the transmitters obtain the corresponding channel knowledge. Due to the variations of the channel, the CSI obtained by the transmitters (CSIT) will be delayed with respect to the actual channel state. Of a particular importance is the extreme case, where the available CSIT in not correlated with the instantaneous channel state. For the aforementioned delayed CSIT setting, new methods of achieving multiplexing gains, termed also as degrees of freedom (DoF), were recently proposed. There, the transmission approach is comprised of two phases, where in the first phase blind transmission is performed. In the second phase, the interference experienced by the unintended receivers in the first phase is evaluated at the transmitters using the delayed CSIT. The interference is then retransmitted such that it provides useful information to both the intended receivers and the receivers which experienced this interference in the first phase.

The purpose of the project is to study different scenarios, were the use of delayed CSIT can provide performance benefits. New transmission schemes are to be proposed, which will provide greater achievable DoF or/and greater sum-rate of the communication system.

Key Research Area

Communications Systems; Nonlinear Optimization


Alexey Buzuverov


Dolivostraße 15

D-64293 Darmstadt



+49 6151 16 - 24401 or 24402


+49 6151 16 - 24404


a.buzuverov (at) hotmai...

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