Arnulf Leuther

Bio: Arnulf Leuther is an academic researcher from Fraunhofer Society. The author has contributed to research in topics: Monolithic microwave integrated circuit & Amplifier. The author has an hindex of 31, co-authored 296 publications receiving 4687 citations.

Wireless sub-THz communication system with high data rate

Abstract: A wireless communication system with a maximum data rate of 100 Gbit s−1 over 20 m is demonstrated using a carrier frequency of 237.5 GHz. The photonic schemes used to generate the signal carrier and local oscillator are described, as is the fast photodetector used as a mixer for data extraction.

Wireless sub-THz communication system with high data rate enabled by RF photonics and active MMIC technology

Abstract: In communications, the frequency range 0.1–30 THz is essentially terra incognita. Recently, research has focused on this terahertz gap, because the high carrier frequencies promise unprecedented channel capacities1. Indeed, data rates of 100 Gbit s were predicted2 for 2015. Here, we present, for the first time, a single-input and single-output wireless communication system at 237.5 GHz for transmitting data over 20 m at a data rate of 100 Gbit s. This breakthrough results from combining terahertz photonics and electronics, whereby a narrow-band terahertz carrier is photonically generated by mixing comb lines of a mode-locked laser in a uni-travellingcarrier photodiode. The uni-travelling-carrier photodiode output is then radiated over a beam-focusing antenna. The signal is received by a millimetre-wave monolithic integrated circuit comprising novel terahertz mixers and amplifiers. We believe that this approach provides a path to scale wireless communications to Tbit s rates over distances of >1 km. Data rates in both fibre-optic and wireless communications have been increasing exponentially over recent decades. For the upcoming decade this trend seems to be unbroken, at least as far as fibreoptic communications is concerned. In wireless communications, however, the spectral resources are extremely limited because of the heavy use of today’s conventional frequency range up to 60 GHz. Even with spectrally highly efficient quadrature amplitude modulation (QAM) and the spatial diversity achieved with multipleinput and multiple-output (MIMO) technology, a significant capacity enhancement to multi-gigabit or even terabit wireless transmission requires larger bandwidths, which are only available in the high millimetre-wave and terahertz region. Between 200 and 300 GHz there is a transmission window with low atmospheric losses3. In contrast to free-space optical links, millimetre-wave or terahertz transmission is much less affected by adverse weather conditions like rain and fog4,5. Here, we present for the first time a single-input single-output (SISO) wireless 100 Gbit s link with a carrier frequency of 237.5 GHz. By combining state-of-the-art terahertz photonics and electronics and by utilizing the large frequency range in the terahertz window between 200 and 300 GHz, we realize a wireless 100 Gbit s link with SISO technology, that is, a link with one transmit antenna and one receive antenna. To date, 100 Gbit s wireless links have only been demonstrated at lower carrier frequencies around 100 GHz (refs 6–8) over a wireless distance of 1 m, with a bit error ratio (BER) of 1 × 10. Because of the limited bandwidth, these systems relied on optical polarization multiplexing and spatial MIMO with more than one wireless transmitter and receiver. Here, a 100 Gbit s wireless transmission capacity is achieved without resorting to MIMO technology. We envisage various applications1,9,10 for such a high-capacity wireless link (Fig. 1). If an end-to-end fibre connection is absent and the deployment of a new fibre link is not economical, as might be the case in difficult-to-access terrains and certain rural areas (last mile problem), or if an already existing fibre connection fails, a permanent or ad hoc wireless connection could help. Furthermore, we anticipate indoor applications, such as highspeed wireless data transfers between mobile terminals and desktop computers. Figure 1 presents a schematic of our 100 Gbit s wireless experiment embedded into an application scenario where an obstacle, here a broad river, is bridged by the wireless link. We first discuss the general system concept, and then provide further details. For the transmitter (Tx) we use a terahertz photonics technology set-up (Fig. 1). We generate exceptionally pure and stable terahertz carriers by heterodyning frequency-locked laser lines11. A control unit contains a single mode-locked laser (MLL), selects the appropriate frequency-locked comb lines, and modulates data on the carrier lines. An optical fibre transmits the modulated carriers together with an unmodulated comb line, which acts as a remote local oscillator (LO), to a remote uni-travelling-carrier photodiode (UTC-PD). By photomixing the LO and the modulated carriers, radiofrequency signals are generated. Optical heterodyning has already been used in earlier works to implement multi-gigabit wireless systems in the 60 GHz band12–14, in the W-band (75–110 GHz, refs 6–8,15,16), at 120 GHz (refs 17,18) and at carrier frequencies beyond 200 GHz (refs 19,20). For the electronic in-phase/quadrature (IQ) receiver (Rx), we use a custom-developed, active millimetre-wave monolithic integrated circuit (MMIC) with a radiofrequency bandwidth of 35 GHz (refs 21,22). This is, to the best of our knowledge, the first active broadband IQ mixer at 237.5 GHz. The Rx comprises a low-noise amplifier (LNA) and a subharmonic downconversion IQ mixer, and is realized in a metamorphic high electron mobility transistor (mHEMT) technology (Supplementary Section S5) featuring a gate length of 35 nm and a cutoff frequency of more than 900 GHz (refs 23,24). The complex data are directly downconverted to the baseband and separated into I and Q signals. Previous works6–8 in the W-band have illustrated the importance of a high carrier frequency. However, to date, no direct downconversion to baseband has been used due to a lack of IQ mixers covering the full W-band. For carrier frequencies beyond 110 GHz (refs 17–20), simple on–off keying modulation and envelope

All Active MMIC-Based Wireless Communication at 220 GHz

Abstract: A wireless data link operating at a carrier frequency of 220 GHz is supporting a data rate of up to 25 Gbit/s in on-off-keyed PRBS as well as complex 256-QAM (quadrature amplitude modulation) transmission. The millimeter-wave transmit and receive frontends consist of active multi-functional millimeter-wave microwave integrated circuits (MMICs), realized in 50 nm mHEMT technology and packaged into split-block waveguide modules. The paper presents system considerations for wireless links in the 200-300-GHz range, discusses the design and performance of dedicated broadband transmit and receive MMICs, and presents link experiments. With an RF transmit power of -3.4-1.4 dBm in the IF frequency range from 0 to 20 GHz , a receiver conversion gain of better than -4.8 dB up to 270 GHz and an estimated noise figure of less than 7.5 dB at 220 GHz, a 231-1 PRBS with a data rate of up to 25 Gbit/s is transmitted over 50 cm and received with an eye diagram quality factor >;3 . At 10 Gbit/s, an uncorrected bit-error rate (BER) of 1.6·10-9 is measured over a distance of 2 m. A 256-QAM signal with approx. 14 Mbit/s is received with an uncorrected BER of 9.1·10-4.

Towards MMIC-Based 300GHz Indoor Wireless Communication Systems

Abstract: SUMMARY This contribution presents a full MMIC chip set, transmit and receive RF frontend and data transmission experiments at a carrier frequency of 300GHz and with data rates of up to 64Gbit/s. The radio is dedicated to future high data rate indoor wireless communication, serving application scenarios such as smart offices, data centers and home theaters. The paper reviews the underlying high speed transistor and MMIC process, the performance of the quadrature transmitter and receiver, as well as the local oscillator generation by means of frequency multiplication. Initial transmission experiments in a single-input single-output setup and zero-IF transmit and receive scheme achieve up to 64Gbit/s data rates with QPSK modulation. The paper discusses the current performance limitations of the RF frontend and will outline paths for improvements in view of achieving 100Gbit/s capability.

Single-Chip 220-GHz Active Heterodyne Receiver and Transmitter MMICs With On-Chip Integrated Antenna

Abstract: This paper presents the design and characterization of single-chip 220-GHz heterodyne receiver (RX) and transmitter (TX) monolithic microwave integrated circuits (MMICs) with integrated antennas fabricated in 0.1- μm GaAs metamorphic high electron-mobility transistor technology. The MMIC receiver consists of a modified square-slot antenna, a three-stage low-noise amplifier, and a sub-harmonically pumped resistive mixer with on-chip local oscillator frequency multiplication chain. The transmitter chip is the dual of the receiver chip by inverting the direction of the RF amplifier. The chips are mounted on 5-mm silicon lenses in order to interface the antenna to the free space and are packaged into two separate modules.

An Overview of Signal Processing Techniques for Millimeter Wave MIMO Systems

Abstract: Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.

Nanometre-scale electronics with III–V compound semiconductors

Abstract: For 50 years the exponential rise in the power of electronics has been fuelled by an increase in the density of silicon complementary metal-oxide-semiconductor (CMOS) transistors and improvements to their logic performance. But silicon transistor scaling is now reaching its limits, threatening to end the microelectronics revolution. Attention is turning to a family of materials that is well placed to address this problem: group III-V compound semiconductors. The outstanding electron transport properties of these materials might be central to the development of the first nanometre-scale logic transistors.

Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

Abstract: Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum. These frequencies also offer the potential for revolutionary applications that will be made possible by new thinking, and advances in devices, circuits, software, signal processing, and systems. This paper describes many of the technical challenges and opportunities for wireless communication and sensing applications above 100 GHz, and presents a number of promising discoveries, novel approaches, and recent results that will aid in the development and implementation of the sixth generation (6G) of wireless networks, and beyond. This paper shows recent regulatory and standard body rulings that are anticipating wireless products and services above 100 GHz and illustrates the viability of wireless cognition, hyper-accurate position location, sensing, and imaging. This paper also presents approaches and results that show how long distance mobile communications will be supported to above 800 GHz since the antenna gains are able to overcome air-induced attenuation, and present methods that reduce the computational complexity and simplify the signal processing used in adaptive antenna arrays, by exploiting the Special Theory of Relativity to create a cone of silence in over-sampled antenna arrays that improve performance for digital phased array antennas. Also, new results that give insights into power efficient beam steering algorithms, and new propagation and partition loss models above 100 GHz are given, and promising imaging, array processing, and position location results are presented. The implementation of spatial consistency at THz frequencies, an important component of channel modeling that considers minute changes and correlations over space, is also discussed. This paper offers the first in-depth look at the vast applications of THz wireless products and applications and provides approaches for how to reduce power and increase performance across several problem domains, giving early evidence that THz techniques are compelling and available for future wireless communications.

Advances in terahertz communications accelerated by photonics

Abstract: This Review covers the state-of-the-art technologies on photonics-based terahertz communications, which are compared with competing technologies based on electronics and free-space optical communications. Future prospects and challenges are also discussed. Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.