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Wireless channels are considered that change over time but remain constant for a certain (coherence) period. This behavior is perfectly captured by block fading channels and affects the performance of the corresponding wireless communication systems. Desired closed-form characterizations of optimal transmission schemes remain unknown in many cases. This paper approaches this issue from a fundamental, algorithmic point of view by studying whether or not it is in principle possible to construct or find such optimal transmission


Wireless communication systems are inherently vulnerable to adversarial attacks since malevolent jammers might jam and disrupt the legitimate transmission intentionally. Of particular interest are so-called denial-of-service (DoS) attacks in which the jammer is able to completely disrupt the communication. Accordingly, it is of crucial interest for the legitimate users to detect such DoS attacks. Turing machines provide the fundamental limits of today’s digital computers and therewith of the traditional signal processing. It has been


While globally optimal solutions to many convex programs can be computed efficiently in polynomial time, this is, in general, not possible for nonconvex optimization problems. Therefore, locally optimal approaches or other efficient suboptimal heuristics are usually applied for practical implementations. However, there is also a strong interest in computing globally optimal solutions of nonconvex problems in offline simulations in order to benchmark faster suboptimal algorithms. Global solutions often rely on monotonicity properties.


We consider globally optimal precoder design for rate splitting multiple access in Gaussian multiple-input single-output downlink channels with respect to weighted sum rate and energy efficiency maximization. The proposed algorithm solves an instance of the joint multicast and unicast beamforming problem and includes multicast- and unicast-only beamforming as special cases. Numerical results show that it outperforms state-of-the-art algorithms in terms of numerical stability and converges almost twice as fast.


Wireless communication systems are to use millimeter-wave (mmWave) spectra, which can enable extra radar functionalities. In this paper, we propose a multi-target velocity estimation technique using IEEE 802.11ad waveform in a vehicle-to-vehicle (V2V) scenario. We form a wide beam to consider multiple target vehicles.


This paper analyzes the average behavior of video streaming systems with adaptation to network bandwidth and player sizes. The main results are formulae for average system performance parameters for given models of codecs, content, players, and networks. Derived expressions are used to study performance limits achievable by adaptive streaming systems, and pose several related optimization problems. Numerical simulations, illustrating the usefulness of the proposed formulae and techniques are also provided


A beam-free approach to channel allocation in a multi-beam
four-color satellite coverage area is taken. Non-Orthogonal
Multiple Access (NOMA) and Orthogonal Multiple Access
(OMA) are compared as methods to serve users nonnecessarily
located on the reference beam. A proportional
fairness policy is employed for the user scheduling. The
naturally occurring SNR imbalances in the user terminal population
are exploited in such a way that NOMA outperforms
OMA, partly due to the blurring of the boundaries of the


The availability and quality of channel state information heavily influences the performance of wireless communication systems. For perfect channel knowledge, optimal signal processing and coding schemes are well studied and often closed-form solutions are known. On the other hand, the case of imperfect channel information is much less understood and closed-form solutions remain unknown in general.