• Tuesday, 13 June, 16:30-18:00, Room Theatre Big Stage
• Session Chair: Nandana Rajatheva (University of Oulu, Finland)

16:30 TWEETHER Future Generation W-band Backhaul and Access Network Technology

Claudio Paoloni (Lancaster University, United Kingdom (Great Britain)); François Magne (WHEN-AB & SARL, France); Frederic Andre (Thales Electron Devices, France); Xavier Begaud (LTCI, CNRS, Télécom ParisTech, Université Paris-Saclay, France); Viktor Krozer (Goethe University of Frankfurt am Main, Germany); Marc Marilier (OMMIC, France); Antonio Ramirez (Fibernova Systems, Spain); José R. Ruiz (Universitat Politècnica de València, Spain); Ruth Vilar (Universitat Politecnica de Valencia, Spain); Ralp Zimmerman (HF System Engineering, Germany)

Point to multipoint (PmP) distribution at millimeter wave is a frontier so far not yet crossed due to the formidable technological challenge that the high atmospheric attenuation poses. The transmission power at level of tens of Watts required at millimeter wave for a reference range of 1 km is not available by any commercial or laboratory solid state devices. However, the availability of PmP with multigigabit data rate is pivotal for the new high density small cell networks for 4G and 5G and to solve the digital divide in areas where fiber is not convenient or possible to be deployed. In this paper, the advancements of the novel approach proposed by the EU Horizon 2020 TWEETHER project to create the first and fastest outdoor W-band (92 - 95 GHz) PmP wireless network are described. For the first time a new generation W-band traveling wave tube high power amplifier is introduced in the transmission hub to provide the enabling power for a wide area distribution.

16:48 Evaluation of IR-HARQ Schemes in FBMC/OQAM Systems with Imperfect CSIR

Màrius Caus and Monica Navarro (Centre Tecnològic de Telecomunicacions de Catalunya (CTTC), Spain); Xavier Mestre and Ana Pérez-Neira (CTTC, Spain); Guillem Femenias and Felip Riera-Palou (University of the Balearic Islands, Spain)

This paper characterizes the sources of distortion of offset-QAM based filter bank multicarrier systems when perfect channel state information at the receiver (CSIR) is not available. The statistical information of the distortion reveals that the mapping scheme, which determines how symbols are inserted in the frequency-time grid, can be optimized to reduce the impact of the estimation error. Moreover, the distortion analysis has been exploited to design variable incremental redundancy hybrid automatic repeat request (IR-HARQ) schemes. Numerical results show that the algorithm devised in this work guarantees the target block error rate (BLER) in low mobility scenarios. In addition, the proposed variable IR-HARQ scheme allows to relinquish up to 75 % of the resources to other users when the initial transmission fails.

17:06 Study on Simple Signal Area Estimation for Efficient Spectrum Measurements

Kenta Umebayashi and Hiroki Iwata (Tokyo University of Agriculture and Technology, Japan); Janne Lehtomäki (University of Oulu, Finland); Miguel López-Benítez (University of Liverpool, United Kingdom (Great Britain))

This paper investigates a signal area (SA) estimation method for spectrum measurements. SA denotes the area (in time/frequency domain) occupied by the primary user's signal. The traditional approach, which utilizes Fourier transform (FT) and energy detector (ED) for SA estimation, can achieve low complexity, but its estimation performance is not very high. For this issue, we apply post-processing to improve the performance of the FT-based ED. Our proposed method, simple SA (SSA) estimation, exploits the correlation of the spectrum states among the neighboring tiles and the fact that SA typically has a rectangular shape to estimate SA with high accuracy and relatively low complexity compared to a conventional method, contour tracing based SA (CT-SA) estimation. Numerical results will show that the S-SA estimation method can achieve better detection performance than CT-SA. Furthermore, it can reduce the computation time compared to the CT-SA estimation.

17:24 Sparse Doubly-Selective Channels: Estimating Path Parameters Unambiguously

Kelvin Chelli and Praharsha Sirsi (Saarland University, Germany); Thorsten Herfet (Saarland University & Intel Visual Computing Institute, Germany)

Doubly selective channels or time-varying multipath channels occur when communication systems are expected to work in a highly mobile environment. The estimation and the subsequent equalization of such channels is a non-trivial task. Thus, a channel estimation scheme that is robust, precise and works with a complexity that is applicable for consumer applications is vital to overcome the effects of such a channel at the receiver. The Matching Pursuit (MP) algorithm is a Compressed Sensing (CS) scheme that is shown to work well in scenarios of high mobility. However, good performance is achieved only when the right search metric is used. In this paper, an appropriate metric for the estimation of the multipath delays is proposed. It is shown that this metric produces an accurate estimate of the multipath delays under different channel conditions. In addition to this, a novel method that implicitly estimates the Doppler shift is proposed. The results show that the proposed schemes accurately estimate a doubly selective channel as compared to the classical MP and the Least Squares (LS) channel estimate. Moreover, an implicit estimation of the Doppler shift reduces the computational burden at the receiver resulting in a lower complexity when compared to the classical MP algorithm. The proposed scheme is implemented for the IEEE 802.11p standard and is applicable in any Orthogonal Frequency-Division Multiplexing (OFDM) based wireless system that is expected to work in highly mobile environments, specifically for 5G.

17:42 Filter Design for 5G BF-OFDM Waveform

David Demmer and Robin Gerzaguet (CEA-Leti, France); Jean-Baptiste Doré (CEA, France); Didier Le Ruyet (CNAM, France); Dimitri Kténas (CEA, France)

A flexible and efficient use of the frequency resource is a key challenge for future wireless technologies. The new requirements are not satisfied by the CP-OFDM which has motivated the research on alternative waveforms. Recently, Block- Filtered OFDM modulation scheme has been proposed. This waveform addresses most of the CP-OFDM's drawbacks at the price of a slight complexity increase of the transmitter. The scheme is based on a filter-bank, a precoding stage that ensures the Near Perfect Reconstruction property and a pre-compensation stage which avoids filtering at the receiver. In this paper, the filter specifications for BF-OFDM are derived and an optimization method based on self-interference rejection is proposed. Optimized filter shape can provide up to 70 dB of Signal-to-Interference Ratio which justifies the Near Perfect Reconstruction property with an enhanced spectral confinement and no channel performance degradation.