Eckhard Grass

Wireless-Optical Network Convergence: Enabling the 5G Architecture to Support Operational and End-User Services

This article presents a converged 5G network infrastructure and an overarching architecture to jointly support operational network and end-user services, proposed by the EU 5G PPP project 5G-XHaul. The 5G-XHaul infrastructure adopts a common fronthaul/backhaul network solution, deploying a wealth of wireless technologies and a hybrid active/passive optical transport, supporting flexible fronthaul split options. This infrastructure is evaluated through a novel modeling. Numerical results indicate significant energy savings at the expense of increased end-user service delay.

Next generation mm-Wave wireless backhaul based on LOS MIMO links

With the evolution of the mobile networks towards more dense and flexible configurations, novel wireless backhaul solutions that can match the high capacity and flexibility demands are required in addition to the fixed fiber optics solutions. In this work we analyze the core backhaul requirements and the related system design challenges for utilizing the mm-wave frequency band due to the large available bandwidth. We determine the key performance metrics in terms of achievable throughput and energy efficiency of several transmission schemes seeking for a viable solution for the small cell backhaul scenario. Finally, an insight to the structure of the baseband domain required for processing multiple transmitted streams at the full system bandwidth is presented for a proposed LOS SM-MIMO system concept.

5G-XHaul: a converged optical and wireless solution for 5G transport networks

The common European Information and Communications Technology sector vision for 5G is that it should leverage on the strengths of both optical and wireless technologies. In the 5G context, a wide spectra of radio access technologies-such as millimetre wave transmission, massive multiple-input multiple-output and new waveforms-demand for high capacity, highly flexible and convergent transport networks. As the requirements imposed on future 5G networks rise, so do the challenges in the transport network. Hence, 5G-XHaul proposes a converged optical and wireless transport network solution with a unified control plane based on software defined networking. This solution is able to support the flexible backhaul and fronthaul-X-Haul-options required to tackle the future challenges imposed by 5G radio access technologies. 5G-XHaul studies the trade-offs involving fully or partially converged backhaul and fronthaul functions, with the aim of maximising the associated sharing benefits, improving efficiency in resource utilisation and providing measurable benefits in terms of overall cost, scalability and sustainability. Copyright

5G infrastructures supporting end-user and operational services: The 5G-XHaul architectural perspective

We propose an optical-wireless 5G infrastructure offering converged fronthauling/backhauling functions to support both operational and end-user cloud services. A layered architectural structure required to efficiently support these services is shown. The data plane performance of the proposed infrastructure is evaluated in terms of energy consumption and service delay through a novel modelling framework. Our modelling results show that the proposed architecture can offer significant energy savings but there is a clear trade-off between overall energy consumption and service delay.

Measurement Results for Millimeter Wave Pure LOS MIMO Channels

In this paper we present measurement results for pure line-of-sight MIMO links operating in the millimeter wave range. We show that the estimated condition numbers and capacities of the measured channels are in good agreement with the theory for various transmission distances and antenna setups. Furthermore, the results show that orthogonal channel vectors can be observed if the spacing criterion is fulfilled, thus facilitating spatial multiplexing and achieving high spectral efficiencies even over fairly long distances. Spacings generating ill-conditioned channel matrices show on the other hand significantly reduced performance.

Multi-Way ranging with clock offset compensation

This paper presents a new approach for reducing the ranging error due to the crystal clock offset. This approach is applicable in cooperative ranging methods like N-Way or Multi-Way ranging, which are mainly used in Wireless Sensor Networks (WSN). Leaving the crystal clock offset error uncompensated leads to propagation of the ranging error through the WSN. In our approach, the crystal clock offset between the nodes is estimated and used to compensate the ranging error. The main advantage of our approach is the smaller number of transmissions compared to other crystal clock offset mitigation techniques. This reduces the energy consumption and minimizes the wireless medium usage for ranging purposes. The simulation results show that, even when a coarse estimation of the clock offset is performed, it has a significant impact (i.e. two orders of magnitude) on the reduction of the ranging error.

Hardware-in-the-loop demonstration of a 60GHz line-of-sight 2×2 MIMO link

The dawn of 5G requires significantly higher data rates, not only for the Radio Access Technology (RAT), but also for the transport network. Line-of-Sight MIMO links based on mmWave radios promise reaching ultra-high throughput with reasonably small antennas. mmWave links with optimally arranged antennas are one viable concept for spatial multiplexing, capable of potentially achieving Gb/s data rates. In the context of mmWave MIMO system design, providing hardware implementation solutions is essential for bridging the gap from theoretical concepts to real-time operational prototypes. In this paper, we focus on the investigation of the BER performance of an orthogonal spatial-multiplexing LoS MIMO link and its robustness to x- and z-axis antenna displacements. Hardware-in-the-loop measurements are performed with a custom demonstrator built for 60GHz LoS MIMO system verification achieving system data rates of 2.5Gb/s at uncoded BER of 1e−4. The results largely confirm the theoretical assumptions and the feasibility of LoS MIMO for short to medium range wireless backhaul applications.

Efïicient and low-complexity space time code for massive MIMO RFID systems

In this paper, a Space-Time Block Code (STBC) based on the Golden number, Golden code is proposed for a massive MIMO-RFID systems. Based on channel modelling for massive MIMO-RFID system, the proposed space-time code is applied to the tag side. Simulation results show that the proposed code for massive MIMO-RFID systems outperforms Alamouti code while simplifying the receivers complexity. The Bit Error Rate (BER) performance of the proposed technique demonstrates that high diversity gain for the tag is achieved leading to a highly reliable and more robust RFID range. Furthermore, the link capacity between the tagged item and the reader can be increased. The proposed RFID technique provides superior performance against the state-of-the-art RFID techniques.

High Throughput Line-of-Sight MIMO Systems for Next Generation Backhaul Applications

Abstract The evolution to ultra-dense next generation networks requires a massive increase in throughput and deployment flexibility. Therefore, novel wireless backhaul solutions that can support these demands are needed. In this work we present an approach for a millimeter wave line-of-sight MIMO backhaul design, targeting transmission rates in the order of 100 Gbit/s. We provide theoretical foundations for the concept showcasing its potential, which are confirmed through channel measurements. Furthermore, we provide insights into the system design with respect to antenna array setup, baseband processing, synchronization, and channel equalization. Implementation in a 60 GHz demonstrator setup proves the feasibility of the system concept for high throughput backhauling in next generation networks.

Efficient and low-complexity joint beamforming algorithm for industrial environments: Measurement-based evaluation

In this paper, an efficient and low-complexity joint beamforming algorithm is proposed for industrial environments. In addition, a configuration of a distributed antenna system (DAS) is proposed for a smart factory. The proposed joint beamforming algorithm in conjunction with the proposed configuration is compared with the conventional and state-of-the-art beamforming techniques in industrial communication. Simulation results show that the proposed algorithm outperforms the conventional beamforming algorithms while simplifying the receivers complexity. The Bit Error Rate (BER) performance of the proposed algorithm demonstrates that good coordination of the interference is achieved leading to highly reliable and more robust wireless communication. The proposed joint beamforming algorithm provides superior performance against the state-of-the-art joint beamforming techniques in industrial environments.