2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2013
ABSTRACT This paper introduces a highly efficient waterfilling-based strategy for optimal use of ... more ABSTRACT This paper introduces a highly efficient waterfilling-based strategy for optimal use of the channel in vehicular or personal ad-hoc communications. The approach provides near optimum allocation of resources and enables small communications devices to establish connections when the energy efficiency is at its best. Instead of calculating the transmit power through conventional waterfilling, the proposed algorithm calculates the waterlevel, thus providing a decision threshold and a strategy for optimum use of the time-variant channel at the same time. The algorithm adapts to the changing average channel quality by applying an exponentially-weighted moving-average (EWMA) trigger to re-calculate the waterlevel. The new algorithm is compared to an efficient non-iterative algorithm that directly calculates the transmit powers in every time-slot. It is shown that the new strategy reduces computation time by approximately 90% compared to the classic approach without compromising performance measures such as transmitted information or energy. Practical implementation is briefly discussed to demonstrate suitability of the algorithm for integration into tomorrow's communication devices.
2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications, 2011
In this paper, we develop several increasingly tight and restrictive performance bounds for OFDM ... more In this paper, we develop several increasingly tight and restrictive performance bounds for OFDM based MIMO wireless communication systems. Starting with channel capacity as the ultimate upper bound on the throughput, step by step we develop tighter bounds on the practically achievable throughput by incorporating typical design constraints. The presented bounds are applied to a Long Term Evolution system, allowing
2014 11th International Symposium on Wireless Communications Systems (ISWCS), 2014
ABSTRACT The joint design of optimal linear Minimum MSE (MMSE) filters at the transmitter and rec... more ABSTRACT The joint design of optimal linear Minimum MSE (MMSE) filters at the transmitter and receiver of a Multiple-Input Multiple-Output (MIMO) system arises as a natural problem when transmitting discrete-time continuous-amplitude sources using analog Joint Source Channel Coding (JSCC). In this work, we derive an explicit closed form solution for the MMSE linear precoder and equalizer of a MIMO system under a transmit power constraint. Such a solution is specially suitable for analog JSCC because it preserves the low complexity and negligible delay distinctive of this type of systems. We also show that the obtained solution for the MMSE linear precoder resembles the waterfilling algorithm and provides the optimal MMSE distribution of the transmit power among the different data streams. The performance of the explicit MMSE transceiver is evaluated in the context of analog JSCC transmissions for MIMOOFDM channels and the obtained results show that the system closely approaches the theoretical limits and outperforms the zero forcing (ZF) precoding. Finally, we derive some interesting properties of MIMO systems with MMSE linear precoder and equalizer, and quantify their superior performance with respect to those that use ZF linear precoding and/or ZF equalization.
2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2013
ABSTRACT This paper introduces a highly efficient waterfilling-based strategy for optimal use of ... more ABSTRACT This paper introduces a highly efficient waterfilling-based strategy for optimal use of the channel in vehicular or personal ad-hoc communications. The approach provides near optimum allocation of resources and enables small communications devices to establish connections when the energy efficiency is at its best. Instead of calculating the transmit power through conventional waterfilling, the proposed algorithm calculates the waterlevel, thus providing a decision threshold and a strategy for optimum use of the time-variant channel at the same time. The algorithm adapts to the changing average channel quality by applying an exponentially-weighted moving-average (EWMA) trigger to re-calculate the waterlevel. The new algorithm is compared to an efficient non-iterative algorithm that directly calculates the transmit powers in every time-slot. It is shown that the new strategy reduces computation time by approximately 90% compared to the classic approach without compromising performance measures such as transmitted information or energy. Practical implementation is briefly discussed to demonstrate suitability of the algorithm for integration into tomorrow's communication devices.
2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications, 2011
In this paper, we develop several increasingly tight and restrictive performance bounds for OFDM ... more In this paper, we develop several increasingly tight and restrictive performance bounds for OFDM based MIMO wireless communication systems. Starting with channel capacity as the ultimate upper bound on the throughput, step by step we develop tighter bounds on the practically achievable throughput by incorporating typical design constraints. The presented bounds are applied to a Long Term Evolution system, allowing
2014 11th International Symposium on Wireless Communications Systems (ISWCS), 2014
ABSTRACT The joint design of optimal linear Minimum MSE (MMSE) filters at the transmitter and rec... more ABSTRACT The joint design of optimal linear Minimum MSE (MMSE) filters at the transmitter and receiver of a Multiple-Input Multiple-Output (MIMO) system arises as a natural problem when transmitting discrete-time continuous-amplitude sources using analog Joint Source Channel Coding (JSCC). In this work, we derive an explicit closed form solution for the MMSE linear precoder and equalizer of a MIMO system under a transmit power constraint. Such a solution is specially suitable for analog JSCC because it preserves the low complexity and negligible delay distinctive of this type of systems. We also show that the obtained solution for the MMSE linear precoder resembles the waterfilling algorithm and provides the optimal MMSE distribution of the transmit power among the different data streams. The performance of the explicit MMSE transceiver is evaluated in the context of analog JSCC transmissions for MIMOOFDM channels and the obtained results show that the system closely approaches the theoretical limits and outperforms the zero forcing (ZF) precoding. Finally, we derive some interesting properties of MIMO systems with MMSE linear precoder and equalizer, and quantify their superior performance with respect to those that use ZF linear precoding and/or ZF equalization.
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Papers by Markus Rupp