Roman Maslennikov

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.

Triangular systolic array with reduced latency for QR-decomposition of complex matrices

The novel CORDIC-based architecture of the triangular systolic array for QRD of large size complex matrices is presented. The proposed architecture relies on QRD using a three angle complex rotation approach that provides significant reduction of latency (systolic operation time) and makes the QRD in such a way that the upper triangular matrix R has only real diagonal elements

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

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Comparative Analysis of Spatial Covariance Matrix Estimation Methods in OFDM Communication Systems

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Impact of mounting structures twists and sways on point-to-point millimeter-wave backhaul links

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.

Analysis of IEEE 802.16m and 3GPP LTE Release 10 technologies by Russian Evaluation Group for IMT-Advanced

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.

Performance analysis of spatial reuse mode in millimeter-wave WPAN systems with multiple links

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.

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

The performance of the orthogonal frequency division multiplexing (OFDM) communication systems may be significantly improved by use of the multiple antenna techniques. One of the multiple antenna techniques applications is the co-channel interference mitigation by exploiting the minimum mean square error (MMSE) signal detection algorithm. The realization of the algorithm requires knowledge of interference plus additive noise spatial covariance matrix (SCM) estimate for every subcarrier of the OFDM symbol. In this paper the independent SCM estimation for every subcarrier of OFDM symbol is considered first and then the algorithm is proposed for the enhancement of such estimate by taking into account the frequency correlation of the propagation channel and additional knowledge of OFDM symbol structure. As a result, it is shown that exploiting of the a priori information about the channel impulse response delay spread and symbol structure may lead to the significant improvement of the estimation accuracy