Low Complexity Beamforming Training Method for mmWave Communications

This paper introduces a low complexity method for antenna sector selection in mmWave Hybrid MIMO communication systems like the IEEE 802.11ay amendment for Wireless LANs. The method is backwards compatible to the methods already defined for the released mmWave standard IEEE 802.11ad. We introduce an extension of the 802.11ad channel model to support common Hybrid MIMO configurations. The proposed method is evaluated and compared to the theoretical limit of transmission rates found by exhaustive search. In contrast to state-of-the-art solutions, the presented method requires sparse channel information only. Numerical results show a significant complexity reduction in terms of number of necessary trainings, while approaching maximum achievable rate.Comment: Submitted to 2017 International Workshop on Signal Processing Advances in Wireless Communications (SPAWC

Manufacturing of nanostructures with high aspect ratios using soft UV-nanoimprint lithography with bi- and trilayer resist systems

In this contribution we introduce new multilayer (bilayer and trilayer) resist systems for the generation of nanostructures with high aspect ratios of up to 14:1 on 4-in. full wafer scale. The bilayer stack consists of a bottom resist layer (lift off polymer LOR1A) and an UV-curable top resist layer (UV-NIL resist mr-NIL210 200 nm). The top resist is structured by UV-nanoimprint lithography with a soft polydimethysiloxane (PDMS) stamp (soft UV-NIL). After removal of the residual layer a wet chemical development is performed to achieve an isotropic undercut underneath the nanostructures in the top layer. This undercut is mandatory in order to perform a reliable and precise lift-off. The bilayer system is applicable on both silicon and fused silica. For a higher variety and combination of different resists, a trilayer system is investigated. A layer stack with new materials for bottom and top layer is presented. An intermediate layer made of silicon oxide by low temperature ICP-PECVD is added between a tailor-made top resist (mr-NIL213FC 200 nm) and an organic transfer layer (UL1). The intermediate layer serves as hard mask in order to etch the bottom layer isotropically utilizing a plasma etch process and thus replacing the wet-chemical development step. Subsequently, a thin metal layer is deposited onto the structured resist stack by electron beam evaporation. After lift-off, a nanostructured metal mask remains on the substrate providing a high selectivity during the following plasma etch step. A cryogenic ICPRIE etch process creates high aspect ratio nanostructures within the substrate. An aspect ratio of 14:1 was achieved

Micro-diffractive optical element arrays for beam shaping

We describe the design of Fourier type array generators and beam shapers as periodic configurations of refractive-diffractive optical elements in microscale to provide specific beam shaping and imaging functionaliies. We investigate how the addition of micro-nanostructures to regular microstructure arrays enables new degrees of freedom for the design of micro-optical systems, in combination with adapted fabrication techniques yields a better optical performance and leads to enhancement of the array concept, uniformity and efficiency