Alexey Sevastyanov

Experimental investigations of 60 GHz WLAN systems in office environment

This paper presents the results of an experimental investigation of 60 GHz wireless local area network (WLAN) systems in an office environment. The measurement setup with highly directional mechanically steerable antennas and 800 MHz bandwidth was developed and experiments were performed for conference room and cubicle environments. Measurement results demonstrate that the 60 GHz propagation channel is quasioptical in nature and received signal power is obtained through line of sight (LOS) and reflected signal paths of the first and second orders. The 60 GHz WLAN system prototype using steerable directional antennas with 18 dB gain was able to achieve about 30 dB baseband SNR for LOS transmission, about 15-20 dB for communications through the first-order reflected path, and 2-6 dB SNR when using second-order reflection for the office environments. The intra cluster statistical parameters of the propagation channel were evaluated and a statistical model for reflected clusters is proposed. Experimental results demonstrating strong polarization impact on the characteristics of the propagation channel are presented. Cross-polarization discrimination (XPD) of the propagation channel was estimated as approximately 20 dB for LOS transmission and 10-20 dB for NLOS reflected paths.

Millimeter-Wave Electronically Steerable Integrated Lens Antennas for WLAN/WPAN Applications

This paper presents design and experimental verification of electronically steerable integrated lens antennas (ILAs) for WLAN/WPAN communication systems operating in the 60-GHz frequency band. The antenna is comprised of a quartz extended hemispherical lens, four switched aperture coupled microstrip antenna (ACMA) elements, and a distribution circuit based on SPDT MMIC switches. The designed ILAs are capable of electronic steering between four different antenna main beam directions in one plane. Fixed beam and electronically steerable ILA prototypes are fabricated and tested. The results are given for two quartz dielectric lenses with the radii of 7.5 and 12.5 mm in order to meet a wide range of WLAN/WPAN requirements. The measured maximum gains of the designed ILAs are 18.4 and 23.2 dBi. The experimental results of the fabricated electronically steerable quartz ILA prototypes prove the simulation results and show

Impact of Polarization Characteristics on 60-GHz Indoor Radio Communication Systems

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Experimental Characterization of E-Band Two-Dimensional Electronically Beam-Steerable Integrated Lens Antennas

and

Comparison of Power Amplifier Non-Linearity Impact on 60 GHz Single Carrier and OFDM Systems

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Electronically beam steerable lens antenna for 71–76/81–86 GHz backhaul applications

angle sector coverage for the lenses with the 7.5 and 12.5 mm radii, respectively. The bandwidth of the ILAs exceeds the frequency band of 57–66 GHz allocated for WLAN/WPAN applications. The designed ILAs meet all the requirements for steerable directional antennas of 60-GHz WLAN/WPAN systems.

Compact MIMO Microstrip Antennas for USB Dongle Operating in 2.5–2.7 GHz Frequency Band

This letter presents experimental results for the polarization impact on 60-GHz indoor radio communication systems. Different transmit and receive antenna polarizations (linear polarizations with different electrical field vector orientations and circular polarizations with different handedness) were used to analyze the degradation in the received signal power due to nonoptimally matched polarization characteristics between the transmit antenna, the propagation channel, and the received antenna. Different signal propagation paths including line-of-sight (LOS) propagation and first- and second-order reflections were investigated. It was found that the degradation due to polarization characteristics mismatch could be as large as 10-20 dB. Polarization characteristics of the transmit and receive antennas providing maximum received signal power were found to be dependent on the type of the signal propagation path. The most robust antenna polarization configuration was identified as a configuration using linear polarization at one end of the communication link and circular polarization at the other end, giving the degradation relative to the optimally matched case of 2-3 dB only.

Statistical channel model for 60 GHz WLAN systems in conference room environment

This letter presents design of E-band integrated lens antennas (ILAs) with two-dimensional (2-D) fully electronical beam-steering capability. Two extended hemispherical quartz lenses with the radii of 7.5 and 12.5 mm and a feeding printed circuit board (PCB) with 16 aperture-coupled microstrip antenna (ACMA) elements arranged in a 2-D order together with a switching circuit were fabricated for experimental verification. A set of the directivity and radiation patterns measurements of the scanning antenna at 77 and 85 GHz is presented. It is shown that the ILA with the radius of 12.5 mm provides the coverage within the solid angle in any direction from the lens axis with the directivity not lower than 20 dBi in the covered area. The ILA with the radius of 7.5 mm provides higher coverage (within ), but with the lower directivity of 16 dBi. A good agreement between the electromagnetic simulations and the measurements is demonstrated. The designed ILAs can be effectively used in different millimeter-wave applications such as WLAN/WPAN communications, automotive radars, imaging systems, and millimeter-wave radio backhaul systems.

Characteristics of indoor millimeter-wave channel at 60 GHz in application to perspective WLAN system

This paper presents a detailed analysis of the impact of power amplifier (PA) non-linearity on the performance of single carrier (SC) and OFDM systems in 60 GHz spectrum. The efficiency of the considered systems was analyzed by estimating values of the power amplifier output backoff needed to meet the requirements on the transmit spectrum mask (TSM) compliance and error vector magnitude (EVM). Different models of the PA including an experimentally measured model for the 60 GHz PA were considered. It was estimated that for many types of modulations and PA models, SC system can have up to 1.5 dB higher output power than OFDM system. However, for the experimental PA model accounting for amplitude modulation-phase modulation distortion in addition to amplitude modulation - amplitude modulation distortion, the difference between the OFDM and SC output power levels was minimal, and OFDM even had approximately 1 dB better performance than SC for the BPSK modulation. A potential improvement in the transmit power due to application of digital predistortion techniques was estimated for both systems to be in the range from 1.5 to 3.4 dB.

Compact bandwidth-optimized two element MIMO antenna system for 2.5 – 2.7 GHz band

Design of an electronically beam steerable integrated lens antenna suitable for 71-76/81-86 GHz backhaul applications is presented. The lens is made from a thermoplastic material and has the aperture size (diameter) of 260 mm ensuring a half power beam width below 1°. The beam steering capability is provided by an antenna array of 4 microstrip patch feed elements and a single pole four through MMIC switch mounted on a high frequency printed circuit board. The half-power (-3 dB) overlapping level of the adjacent beams is achieved by selecting a proper distance between the feed elements in the array. The lens antenna has a WR-12 waveguide interface and can be easily integrated with traditional millimeter-wave radio systems. Measurement results of the fabricated lens antenna prototype with electronic beam steering are provided. A successful trial of the prototype was performed with a commercial 71-76/81-86 GHz system during a 3-month test at a mobile operators network.