Guido H. Bruck

Combining Mimo with Network Coding: A Viable Means to Provide Multiplexing and Diversity in Wireless Relay Networks

In this paper, a two-step communication protocol combined with virtual MIMO (Multiple Input Multiple Output) and network coding technique is proposed. The protocol is therefore termed MINEC (MIMO Network Coding). A three nodes network with multi-antennas on relay node is taken as an illustrative example of MINEC. Theoretical and simulative analyses of the MINEC performance under the assumption of a binary symmetric relay channel model are carried out. It is found that MINEC performs equivalent to a 2x2 V- BLAST MIMO and a two 2x1 Alamouti MISO in transmitting phase and forwarding phase, respectively. Theoretical and simulative analyses prove that MINEC protocol facilitates more reliable transmission and higher throughput.

On the Equivalence of MMSE and IRC Receiver in MU-MIMO Systems

In order to combat the residual interference in multiuser multiple-input and multiple-output systems (MU-MIMO), a number of low-complexity interference aware type of receivers have been considered. In this letter, single layer Minimum Mean Square Error (MMSE) and Interference Rejection Combiner (IRC) are applied in MU-MIMO transmission. Based on some very simple but extremely useful matrix manipulations, their equivalence is proven analytically and demonstrated via Monte Carlo simulations.

Closed loop transmission with precoding selection in LTE/LTE-Advanced system

Closed-loop transmission combined with MIMO (multiple-input multiple-output) and OFDM (orthogonal frequency division multiplexing) technologies have drawn most attentions during development of the 4G systems (fourth generation of mobile communication systems). In LTE (Long Term Evolution) and LTE-Advanced systems, which are proposed by 3GPP (Third Generation Partnership Project) to be the most competitive candidate for the 4G systems, the codebook based precoding scheme is deployed for realizing the closed-loop transmission concept. This scheme introduces the precoding matrix selection at the receiver and precoding operation at the transmitter and achieves a good tradeoff between the system complexity and the performance gain given by the closed-loop transmission. In this manuscript, the authors give a brief overview of the LTE/LTE-Advanced system downlink transmission. Furthermore, different precoding matrix selection criteria are discussed at the aim of optimal receiver design. Following the analytical and numerical results, the authors conclude that the minimum post mean squared error based criterion is the optimal candidate for precoding matrix selection at the receiver in LTE compliant systems.

The Cognitive Radio paradigm for Ultra-Wideband systems: The European Project EUWB

In this paper we will discuss the research activity in Cognitive Radio (CR) for Ultra-Wideband (UWB) systems within the FP7 European Project EUWB. We cover the issues related to the interference and coexistence between narrowband (NB) and UWB communication systems in a realistic scenario. We show the great potential of the UWB technology in adapting the transmitted spectrum to counteract NB interference and at the same time to guarantee low spectral emissions over existing narrowband communications. We also discuss the role of location capable radios on cognitive UWB nodes.

On the physical layer performance with rank indicator selection in LTE/LTE-Advanced system

The 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) and LTE-Advanced activities work toward the evolved UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access (E-UTRA), and the solution of IMT-Advanced (International Mobile Telecommunications) and systems beyond. The combination of OFDM (orthogonal frequency division multiplexing) and MIMO (multiple-input multiple-output) has been introduced into LTE and LTE-Advanced systems for achieving high system capacity. Furthermore, the closed-loop concept with codebook based precoding MIMO and transmission layers selection, termed as RI (rank indicator) selection have also been included to provide robust transmission in mobile wireless communication scenarios and increase the cell coverage. This manuscript focuses on the RI selection study and implementation in LTE and LTE-Advanced systems and illustrates the downlink performance evaluation and comparison with different RI selection schemes. According to the analytical and numerical results from an LTE and LTE-Advanced compliant simulator, the mutual information based scheme is chosen as the best candidate for RI selection.

On MIMO with successive interference cancellation applied to UTRA LTE

The long term evolution of UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access, abbreviated as UTRA LTE, makes use of OFDM (orthogonal frequency division multiplexing) combined with MIMO (multiple-input multiple-output), termed MIMO-OFDM. The potential maximization of transmitted data rates has been considered a most beneficial feature of MIMO schemes. This maximization shall be strived for by spatial multiplexing. In particular, high data rates in the downlink have been considered desirable. Also, in view of an efficient implementation, the downlink requires a thorough assessment. Therefore, the authors will discuss the deployment of spatial multiplexing in the UTRA LTE downlink and will show that the performance of successive interference cancellation (SIC) based data detection techniques for MIMO-OFDM is beneficial.

A Spectrum Sensing Prototype for TV White Space in China

TV white space (TVWS) has been considered a favorable spectrum for sharing with other spectrum deficient technologies. There are three popular TV standards in China: the Digital Terrestrial Multimedia Broadcast (DTMB), China Multimedia Mobile Broadcasting (CMMB) and PAL-D/K (Phase Alternating Line -D/K). In this paper we present a prototype platform for experimental spectrum sensing, which is developed in-house to test TVWS spectrum sharing for all the three popular TV standards. We discuss the details on the prototype architecture, the spectrum sensing algorithms and the testing setup in this paper. The performance results show that the developed prototype platform can detect the signals from all the three TV standards robustly and efficiently.

Leadless pacing using induction technology: impact of pulse shape and geometric factors on pacing efficiency

AIMS Leadless pacing can be done by transmitting energy by an alternating magnetic field from a subcutaneous transmitter unit (TU) to an endocardial receiver unit (RU). Safety and energy consumption are key issues that determine the clinical feasibility of this new technique. The aims of the study were (i) to evaluate the stimulation characteristics of the non-rectangular pacing pulses induced by the alternating magnetic field, (ii) to determine the extent and impact of RU movement caused by the beating heart, and (iii) to evaluate the influence of the relative position between TU and RU on pacing efficiency and energy consumption. METHODS AND RESULTS In the first step pacing efficiency and energy consumption for predefined positions were determined by bench testing. Subsequently, in a goat at five different ventricular sites (three in the right ventricle, two in the left ventricle) pacing thresholds using non-rectangular induction pulses were compared with conventional pulses. Relative position, defined by parallel distance, radial distance, and angulation between TU and RU, were determined in vivo by X-ray and an inclination angle measurement system. Bench testing showed that by magnetic induction for every alignment between TU and RU appropriate pulses can be produced up to a distance of 100 mm. In the animal experiment pacing thresholds were similar for non-rectangular pulses as compared with conventional pulse shapes. In all five positions with distances between 62 and 102 mm effective pacing was obtained in vivo. Variations in distance, displacement and angle caused by the beating heart did not cause loss of capture. At pacing threshold energy consumptions between 0.28 and 5.36 mJ were measured. Major determinants of energy consumption were distance and pacing threshold. CONCLUSION For any given RU position up to a distance of 100 mm reliable pacing using induction can be obtained. In anatomically crucial distances, up to 60 mm energy consumption is within a reasonable range.

System implementation study on RSSI based positioning in UWB networks

The Ultra-Wideband Radio Technology (UWB-RT) enables accurate Location and Tracking (LT) applications. However, the required and sophisticated time of arrival (ToA) ranging procedure relies on accurate synchronizations and time measurements. Non-cooperative nodes, not supporting the ToA feature, cannot be localized with this LT approach. Other LT approaches exploit the received signal strength (RSS) or received signal strength difference (RSSD). Simulations of RSS based localization in UWB networks showed promising performance results. In this paper, the authors introduce a RSS based LT demonstrator, build up with conventional Certified Wireless USB (CWUSB) sticks, using multiband UWB-RT. Different LT algorithms are tested. In a small UWB network, measurements of the localization accuracy show a root mean square error (RMSE) of about 0.33 meters.

A DVB-T2 receiver realization based on a software-defined radio concept

When DVB-T (Digital Video Broadcasting - Terrestrial) was introduced in the 1990s, it was impossible to foresee the upcoming demand for HDTV devices. Thus, a revision of this broadcasting standard, namely DVB-T2, was necessary. Recently finalized, this standard is targeting to high-definition television (HDTV). To pave the way to commercialization, an appropriate implementation concept and its corresponding validation are of utmost importance. Without a doubt, the most challenging requirements introduced by the DVB-T2 specification are an FFT (Fast Fourier Transform) size of up to 32k samples, 256-QAM (Quadrature Amplitude Modulation) and LDPC (Low-Density Parity-Check) coding with a block size of 64800 bits. Within this manuscript, the authors present a software-defined radio based realization of a demonstrator platform. This platform employs a combined DSP (Digital Signal Processor) and FPGA (Field-Programmable Gate Array) solution being capable of meeting these requirements.