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In Compressed Sensing, a real-valued sparse vector has to be recovered from an underdetermined system of linear equations. In many applications, however, the elements of the sparse vector are drawn from a finite set. Adapted algorithms incorporating this additional knowledge are required for the discrete-valued setup. In this paper, turbo-based algorithms for both cases are elucidated and analyzed...
Using a compressive sensing framework, we investigate the performance of a practicable sub-Nyquist radar system, which is based on a set of parallel bandpass filters for extracting range information of sparse target objects. In particular, the system employs an equivalent measurement matrix optimized based on a sparse ruler approach known from combinatorical number theory. First, we address the connection...
We consider practicable subsampling for sub- Nyquist radar systems based on a set of parallel bandpass filters for extracting range information of sparse target objects. Based on a compressed sensing framework, the corresponding measurement matrix composed of blockwise selected rows from a Fourier matrix is optimized, using sparse rulers known from combinatorial number theory. As an alternative cyclic...
Information processing characteristics (IPC) provide a general framework for the analysis of a coding scheme. In this paper, we utilize IPCs to obtain performance estimates for the end-to-end coded channel for bit-interleaved coded modulation (BICM) using a given modulation format and coding scheme, i.e., its bit error rate and capacity. The proposed method enables to fully decouple the analysis of...
Noncoherent receivers are widely regarded as the key to low-complexity detection in impulse-radio ultra-wideband systems. In this paper, building upon an information theoretic performance assessment of an equivalent discrete time model of autocorrelation-based noncoherent multiple-symbol differential detection of IR-UWB, design rules for the application of (bit-interleaved) coded modulation in realistic...
We study Tomlinson-Harashima precoding (THP) for the broadcast scenario, i.e., transmission from a central base station to a number of scattered, non-cooperating mobile stations. In the linear description of THP, given the data symbol, a suited signal representation is selected from an effective signal constellation. In this paper, we assess how to choose the effective signal constellation. It is...
Power efficiency of noncoherent receivers for impulse-radio ultra-wideband (IR-UWB) transmission systems can significantly be improved, on the one hand, by employing multiple-symbol differential detection (MSDD), and, on the other hand, by providing reliability information to the subsequent channel decoder. In this paper, we combine these two techniques. Incorporating the computation of the soft information...
The high peak-to-average power ratio (PAR) of the transmit signal is one serious issue, which occurs in orthogonal frequency-division multiplexing (OFDM). Hence, the application of a PAR reduction algorithm, which controls the peak-power of the transmit signal, is indispensable. In this paper, we consider selected mapping (SLM), a very popular technique for PAR reduction and its recently proposed...
In order to reduce the peak-to-average power ratio (PAR) of multi-antenna orthogonal frequency-division multiplexing (MIMO OFDM) systems selected mapping (SLM) and its MIMO extensions are considered. With SLM the transmission of some side information is necessary. In this paper, we focus on the approach of embedding the side information into the OFDM frame using combinations of unrotated and ??/4...
With the aim of reducing its search complexity, we study a stopping radius for the sphere decoder (SD) algorithm. We compare two variants in setting this stopping radius. In particular, we consider a stopping radius, based on a lower bound on the packing radius, which preserves the optimality of the SD output, and a stopping radius which is based on the statistics of the underlying search problem...
The capacity of OFDM with 4-QAM modulation per carrier over channels with clipping at the transmitter side is studied. For this, the individual capacities of the OFDM frames are considered. It is shown that capacity is linearly related to the energy of the OFDM frame after clipping. Based on the insight that the power leakage is the main source of the loss, via geometrical considerations a very tight...
Multiple-symbol differential detection (MSDD) is a powerful technique for power-efficient low-complexity autocorrelation receivers in ultra-wideband impulse-radio (UWBIR) systems. Since MSDD can be represented as a tree search problem, it is efficiently implemented by the Sphere Decoder (SD) algorithm. In this paper, we introduce a novel stopping criterion for the SD, which is based on a lower bound...
The major drawback of orthogonal frequency-division multiplexing (OFDM) is its high peak-to-average power ratio (PAR), which gets even more substantial if a transmitter with multiple antennas is considered. To overcome this problem, in this paper, the partial transmit sequences (PTS) method—well known for PAR reduction in single antenna systems—is studied for multiantenna OFDM. A directed approach,...
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