Ioannis Petropoulos

2

A 2 × 2 Switch Matrix operating at the 3.3-3.8 GHz frequency band is presented. The design is based on PIN diode switch elements. The achieved isolation is below 80 dB, while the insertion loss is less than 2 dB for the full frequency band. The proposed 2 × 2 Switch Matrix is used as the antenna switching element in the RF Front-End of a WiMAX Relay Station, supporting both Time-domain Transmit and Receive and Simultaneous Transmit and Receive operation in Time Division Duplexing mode.

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This paper aims at describing the advantages of using relay and repeater elements in a wireless network and especially in a network based on WiMAX technology. Apart from a description of the relay and repeater entities, a comparison between them is presented based on computer simulations. All presented material is based on the findings and results of the FP7-REWIND project.

2 Switch Matrix for WiMAX Relay Station Applications

A relay station (RS) is a smart transceiver used under a 4G wireless network in order to extend network’s coverage and capacity. It uses an antenna system that includes an antenna for connecting the relay with the end users (access link) and the RS with the base station (backhaul link). In this paper, a 7.9dBi access and 11.4dBi backhaul antennas are presented for the frequency range of 3.3 to 3.8GHz. The antennas are simulated and fabricated, and relevant measured results in terms of return loss and radiation pattern are presented and analyzed. Considering that the planes of those two antennas are positioned in an angle ω (omega), two antenna configuration geometries are tested in terms of coupling. The experimental results of S21 for several values of the angle ω showthat the interaction between the radiating elements is dependent on their relative position. Simulated and experimental results are in good agreement, showing coupling typically less than −40dB. A comparison in terms of coupling between the proposed antennas and commercial ones proves that the suggested antennas provide 10dB lower coupling.

Relay vs. Repeater Architectures in WiMAX

In this paper two novel antennas, suitable for access and backhaul links, are designed, fabricated and tested for a Relay Station in a WiMAX wireless network. A single modifled E-shaped patch antenna is described, presenting 10dB gain over 12.4% bandwidth. This antenna element is used for the design of a 4 £ 4 planar array which provides experimental gain of 21.2dB. The antenna system on the Relay Station operates at 3.4GHz and includes one single antenna element for access link realization and an antenna array for the backhaul link realization. These antennas are installed in two conflguration arrangements and tested in terms of their radiation performances and coupling efiects. The simulated and measured results are quite satisfactory and in good agreement at which the maximum coupling between the access and backhaul antennas is found below i25dB for all tested cases.

A Novel Design of Microstrip Arrays for Relay-Based Wireless Network

In this study, a planar 4×4 phased array including modified E-shaped radiation elements is designed and fabricated to be incorporated in a Relay Station (RS) for realizing the communication with the super-ordinate Base Station. The proposed array provides 12.4% bandwidth at the 3.5GHz frequency band and gain of 21.2dB. Moreover a beamforming module is designed and simulated, aimed to be connected to the proposed array and realizing beamforming applications. This module provides 650 MHz bandwidth around 3.5GHz frequency band and is used for proper power division and controlling the amplitude/phase of the excitation currents.

Coupling Measurements of an Antenna System Suitable for Relay-Aided WiMAX Network

In this study, two linear coplanar array antennas based on Indium Phosphide (InP) substrate are designed, presented and compared in terms of bandwidth and gain. Slot introduction in combination with coplanar structure is investigated, providing enhanced antenna gain and bandwidth at the 60 GHz frequency band. In addition the proposed array antennas are evaluated in terms of integration with a high-speed photodiode and investigated in terms of matching, providing a bandwidth that reaches 2 GHz. Moreover a potential beam forming scenario combined with photonic up-conversion scheme has been proposed.

Phased array antenna suitable for a relay-aided WiMAX network

In this study two types of coplanar waveguide (CPW) array antennas are designed and analyzed for use in a 60GHz Radio over Fiber indoor network. The first one is based on high permittivity Rogers 6010 and Indium Phosphide (InP) substrates incorporating slots as radiating elements. The second one utilizes stacked geometry based on the above substrates. Both arrays present more 1 GHz bandwidth and 10dBi gain. Furthermore they can provide beam-forming operation by properly adjusting the signal’s amplitude and phase. A Least Mean Square (LMS) algorithm is generated for this purpose and the radiation pattern is steered accordingly. At last, a photodiode is simulated using equivalent circuit and is adopted with the proposed arrays, and an optical beam forming scenario is discussed.

Evaluation on a 60 GHz radio over fiber system employing photonic up conversion and optically beam formed linear array antenna for broadband indoor access

A low cost converged wireline and 60GHz wireless hybrid system utilizing a single wavelength is proposed, employing two single electrode LiNbO3 modulators for all-optical mm-wave frequency up-conversion and baseband modulation, respectively. Additionally, a novel 15dBi, broadband, coplanar based, photonic patch array antenna is designed on a high dielectric substrate for application as an indoor compact photonic-wireless transceiver. In order to evaluate the fiber-wireless system performance a microwave/optical/wireless design is utilized, employing 3Gb/s orthogonal frequency division multiplexed (OFDM) broadband wireless and passive optical network (PON) signals, co-propagating in a single mode fiber (SMF). An acceptable performance is calculated for a 10m indoor wireless channel and a PON urban link in the order of up to 20km, respectively. At last, a comparison of alternative RoF/PON photonic up conversion schemes is presented.

Novel 60 GHz CPW array antennas with beam-forming features for indoor wireless over fiber networks

This research presents a 3.5 GHz frequency band phased array unit which is integrated in a prototype WiMAX Relay Station. It provides radiation patterns with steerable main lobes and side lobe levels suppression through the control of both amplitude and phase excitation currents. The proposed unit enables adaptive backhauling between prototype Relay Station and its super-ordinate Base Stations and extends its capabilities towards mobile relay applications in WiMAX relay networks.