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Optically Beam-formed Antennas For Adaptive Broadband Fixed And Mobile Wireless Access Networks

Deliverables

This result allows to assess the number of elements of the antenna array that ensure the required performance level in terms of carrier-to-interference ratio in a TDD/TDMA wireless network employing beam switched antennas. This result may be of interest to manufacturers of BS antennas willing to optimise the complexity/cost of their systems. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
The packaging of photonic integrated chips (PIC) has been investigated and developed for the PICs developed in OBANET, a Multiple Wavelength Laser (MWL) and a Mach-Zehnder Interferometer (MZI) modulator. The important building blocks are: VP connector with wide band properties and high integration capability, alumina CPW lines whose geometry can be adapted to the one of the chip CPW lines while keeping the characteristic impedance at 50ohms, 50ohms wide band integrated loads. All of these building blocks have been either simulated or measured or both. Apart from the RF issues, care has been taken for the optical coupling aspects and TEC cooling. This work will allow getting module performances close to the chip performances to be packaged, which is the main goal of the packaging activity. Because of the delay in the chip development experimental verification will not be possible within the duration of the OBANET project. More information on the OBANET project can be found on the projects website: http://ist-obanet.upv.es/ .
A new optical beamforming network based on arrayed-waveguide grating (AWG) and depressive media has been invented. This novel scheme allows the straightforward implementation of highly flexible multibeam architectures, reducing the number of required optical components with respect to other proposals. The principle of operation is based in the spectral periodicity of the AWG. This architecture allows also the implementation of photonic-microwave filters. This novel optical beamforming network offers several advantages with respect to other approaches, such as flexibility or reduced number of required components, besides the known advantages of using a photonic beamformer with regard of traditional ones based either in DSPs or RF/IF beamforming. The ability to shape and steer a beem, may be of interest to manufacturers and service providers as allows improving the performance of wireless networks and the implementation of advanced features such as user location and tracking or overcoming service drops. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .
This novel modulation technique allows to remotely feed a BS with information signals in its original base-band or IF frequency and modulated on a RF carrier at frequencies up to 60GHz using state-of-the-art components. This allows transmitting the same information from the Bs through a wireline access network and through a wireless access network. The technique allows long fiber spans due to its dirpersion-tolerant nature and simplifies the hardware requirements at the Control Station due to its frequency doubling capabilities. This technique may be of interest for operators that want to operate simultaneously in different frequency bands due to service upgrading or unability to yield the cable plant, or to implement disaster-recovery strategies (e.g. the wireless link can be used as back-up for the wired link). More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .
The results are envisaged to be utilised in next generation smart antennas for mobile broadband systems. One of the reasons of the deployment of 3G smart antennas (UMTS CDMA) is the improvement of co-channel interference. Future broadband-smart antennas shall reuse the results, hereby described. The Space Division Multiple Access (SDMA) realised by smart antennas for broadband access shall have the additional advantage to reduce the EME whose impacts on the environment may be higher at these frequency bands (tens of GHz). This result shows how employing switched beam antennas the carrier-to-interference ratio, which limits the number of active users and coverage of a given BS, can be increased. It also shows how the number of elements influences the obtained CIR. Design rules are provided to optimise the complexity to performance ratio. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
Target Broadband Wireless communications at mmwave e/o multi frequency. In order to realize flexible wireless access having high channel capacity, innovative versatile antennas are necessary, having the following characteristics: - Broadband e/o multi – frequency. - Multi-beams e/o reconfigurable, allowing the re-configuration depending upon traffic needs and faults. - Capable to be adapted at surfaces of pre-assigned geometry in order to reduce impacts on the environment. - Without retro radiation. - Easy to be installed. - Able to respect constraints on the radiating behaviour in the near zone (EMC and radiation pattern alteration). Antenna systems based on optical beamforming technologies, developed within Obanet project, meet almost above requirements, its potential usage is envisaged for arrays for LMDS or point-to-multipoint FSO transmitters. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
The measurements of the spatio temporal directional channel at 40GHz are carried out by using the 40GHz array antenna of four antenna elements in broad-scale (e.g. 500 - 1000MHz). The broad-scale radio channel is excited by a test signal of a certain bandwidth piecewise with stepped LO frequencies. The partly measured channels are subsequently composed in the frequency domain whereby broadband channel measurements arise. For exciting channels a multi-sine signal is applied as the transmit signal. The discontinuity between the channel transfer functions between the partly measured frequency bands may not be excluded and these can be eliminated by the system calibration and by utilizing appropriate signal processing. The estimation of the channel parameter is accomplished after measurements off-line. The main advantage of this channel measurement concept lies in the broadband spatio temporal directional channel characterisation with small hardware investment. The relative large measurement repeat frequency is contrarily the limitation of this concept. Thus, this measurement concept represents the trade-off between the frequency sweeping method and the broadband correlation method in terms of the performance and the cost. More information on the OBANET project can be found on the project’ s website: http://ist-obanet.upv.es/ .
A novel Direction-of-Arrival (DOA) algorithm based in power measurements has been proposed and experimentally demonstrated in the 40 GHz band. It allows to estimate the direction of arrival and the position of a mobile user within a given coverage area without the need of employing DSPs which have limited performance in broadband real-time implementations. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
A novel optical delay line based in an AWG and dispersive fibre is proposed and a detailed model provided. The model allows first to predict the performance of the device from the physical parameters defined in the design stage, and secondly the performance of the delay line when used as a building block to implement optical beamforming networks, photonic microwave filters or other optical signal processing devices. This result allows to accurately design an optical true-time delay line based in AWGs. This delay line can be used as building block to implement optical beamforming networks, photonic microwave filters or, in general, optical signal processing functionalities. Photonic signal processing has many advantages, such as low loss and size, high dynamic range, extremely huge bandwidth, among others. The model allows fixing the design parameters to optimise the performance of the optical delay line. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
Fabrication of a 40GHz band 4-elements patch array antenna. Planar antenna elements have been printed on an aluminum ceramic substrate of 0.1 mm thickness only. In order to cut down dielectrical losses as low as possible and positive influence bandwidth and radiating efficiency, the substrate was mounted above an air filled cavity. This printed antenna has an inter-element separation of 3.75mm and 2.9mm-female coaxial connectors. The antenna impedance matching has been tuned at 42.7GHz with a 3GHz bandwidth at 10dB return loss limit. This antenna has application in many fields and the design expertise gained in OBANET and the measured results will be a solid base to continue working in the design of similar antennas to be used in laboratory environment. Know-how and test equipment at 40 at 60GHz is available for future R&D activities. More information on the OBANET project can be found on the projects website: http://ist-obanet.upv.es/ .
To our knowledge, this is the first time that an optically beamformed switched beam antenna performance has been evaluated, including radiation pattern and 155 Mb/s 64-QAM 42.7 GHz data transmission measurements in both uplink and downlink direction. It has been also proved that the E/O and O/E conversion and photonic processing of the information signal do not impose any limitation in terms of the measured signal-to-noise ratio, therefore being transparent from a system point of view. This result demonstrates the feasibility of optically beamformed antennas operating in the 40 GHz band to implement advanced smart functionalities for next generation multimedia applications. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/.
A novel optical beamforming architecture based in optical Butler Matrices has been proposed. This architecture has straightforward multi-beam applications, reducing the number of optical components required. Besides the benefits derived from its photonic nature (low loss/size, huge bandwidth, etc), this architecture allows simultaneous and independent control of all beams, increasing significantly the flexibility of the beamforming network. This novel optical beamforming network offers several advantages with respect to other approaches, such as flexibility or reduced number of required components, besides the known advantages of using a photonic beamformer with regard of traditional ones based either in DSPs or RF/IF beamforming. In particular, this architecture is useful to implement SDMA networks, due to its capability to generate and steer N-beams independently. The ability to shape and steer a beam, may be of interest to manufacturers and service providers as allows improving the performance of wireless networks and the implementation of advanced features such as user location and tracking or overcoming service drops. More information on the OBANET project can be found on the projects website: http://ist-obanet.upv.es/ .
Direction-of-Arrival (DOA) estimation and uplink beam steering at 40GHz applying photonic millimetre-wave generation and distribution (optical LO-distribution network) has been demonstrated. The DOA estimation was performed using base-band signal processing after down conversion to the IF band. Uplink beamsteering has been demonstrated with 155Mbit/s OQPSK data signals. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .
This evaluation platform allows to characterise beamforming networks operating above 35GHz. The platform is computer controlled and allows measuring the radiation pattern of an antenna and to perform data transmission in both uplink and downlink directions. More information on the OBANET project can be found on the projects website: http://ist-obanet.upv.es/ .
High power Monolithic Microwave Integrated Circuits (MMIC) drivers have been realised, packaged and tested exhibiting 18dB gain, an output power 1dB compression point of 28.5dBm in a - 3dB gain bandwidth of 39 - 43GHz. It has been fabricated in a GaAs 0.15um pHEMT process and has a size of approx. 2x3mm. This is one in a series of several mmwave amplifiers. Our laboratory also has a large experience in the design and test of X-band high power amplifiers for communications, space and military market. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
This results allows to accurately predict the performance of Wavelength-Division Multiplex (WDM)-based true-time delay lines (including passive and active components) as building blocks to implement optical beamforming networks, photonic microwave filters or, in general optical signal processing functionalities. Photonic signal processing has many advantages, such as low loss and size, high dynamic range, extremely huge bandwidth, among others. A thoroughful noise model has been developed. This model can be applied to the design of photonic beamforming networks, photonic microwave filters and other optical signal processing structures. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .
Five 40GHz photo-receivers have been fabricated and packaged. They integrate waveguide photodiode technology and Monolithic Microwave Integrated Circuits (MMIC) amplifier. The average RF power is ~ -3dBm for 0dBm input optical power. The amplitude ripple is +/- 0.5 dB. The RF responsivity of the photoreceiver corresponds to -19dBm RF power for - 8dBm input optical power. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .
The result is envisaged to be utilised in next generation smart antennas for Mobile Broadband Systems. The deployment of 3G smart antennas must have low impact on PHY and MAC layers in such a way that smart antenna are almost transparent to the base station. This result describes the modifications that must be incorporated to the MAC protocol as defined by on-going standardisation bodies in the field of broadband wireless access networks in order to be able to implement smart antenna functionalities with minor impact to the protocol overhead. Software has been developed to simulate the performance of the modified protocols. More information on the OBANET project can be found on the project’s website: http://ist-obanet.upv.es/ .
Four high power Monolithic Microwave Integrated Circuits (MMIC) drivers modules have been realised, packaged and tested exhibiting 18 dB gain, a maximum RF output power greater than 25dBm with performances close to the on-chip performances. Experience has been gained in the packaging of such high power/high bandwidth devices. More information on the OBANET project can be found on the project's website: http://ist-obanet.upv.es/ .

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