- PhD research student with over 6 years of R&D experience.
- Received BSc and MSc in Electrical Engineering from University of Engineering & Technology, Pakistan in 2009 and 2013 respectively.
- Project Member of RAIPD 5G (Radio Access Technologies with Photonic Infrastructure for Dense User Environment), an EU Horizon 2020-Japan Collaboration Project
- Photonic Generation and Radio-Over-Fibre Transport of Millimetre Wave
- RoF based Millimetre Wave MIMO for Future Mobile/Communication Networks
- 25GHz/60GHz Communication based systems for 5G
Assistant Lecturer (School of Computing)
- CO883 Systems Architecture
- CO881 Object Oriented Programming
- CO882 Advanced Object Oriented Programming
- CO520 Further Object Oriented Programming
- CO545 Functional and Concurrent Programming
- CO320 Introduction to Object Oriented Programming
- CO324 Computer Systems
- CO325 Foundations of Computing II
- CO322 Foundations of Computing I
Lab Demonstrator (School of Engineering and Digital Arts)
- EL024 Electromagnetics for Engineers
- EL025 Electrical Principles and Measurements
- EL026 Analogue Electronics
- EL027 Semiconductor and Digital Electronics
- EL313 Introduction to Programming
- EL562 Computer Interfacing
Habib, U. et al. (2019). Single Radio-over-Fiber Link and RF Chain-based 60GHz Multi-beam Transmission. Journal of Lightwave Technology [Online]. Available at: https://doi.org/10.1109/JLT.2019.2896778.An efficient multi-user transmission scheme at 60 GHz using a single-feed Leaky Wave Antenna (LWA) and hence requiring only a single Radio-over-Fiber link and single RF chain is presented. A Subcarrier Multiplexed (SCM) signal carrying the different users' data is transported over 2.2km of optical fiber and then upconverted to the 60 GHz band for transmission to multiple spatially separated users through the beam steering characteristics of the LWA. An overall sum data rate, the combined rate from all users, of 10.6 Gb/s using 16-QAM modulation serving 10 users over a transmission bandwidth of 3.05 GHz or 20 users with QPSK over 6.1 GHz span, is achieved experimentally. The theoretical sum data rates for 6.1 GHz bandwidth for different numbers of users are calculated, considering the SNR degradation due to the angularly dispersed LWA beam, showing that data rates over 30 Gb/s can be obtained. Finally, a system design that improves coverage and spectrum efficiency through operating multiple LWAs with a single RF chain is demonstrated.
Wang, G. et al. (2018). Highly efficient optical beam steering using an in-fiber diffraction grating for full duplex indoor optical wireless communication. Journal of Lightwave Technology [Online] 36:4618-4625. Available at: https://doi.org/10.1109/JLT.2018.2832200.Diffraction gratings have been widely used in wavelength-controlled non-mechanical laser beam steering for high data-rate indoor optical wireless communications (OWC). Existing free-space diffraction gratings suffer from inherent difficulties of limited diffraction efficiency, bulky configuration, high cost and significant coupling loss with optical fiber links. In this work, a new optical approach for highly efficient, compact and fiber compatible laser beam steering using an in-fiber diffraction grating is proposed and experimentally demonstrated for the first time to our best knowledge. In-fiber diffraction is made possible based on a 45° tilted fiber grating (TFG), where wavelength dependent lateral scattering is obtained due to the strongly tilted grating structure. Improved diffraction efficiency of 93.5% has been achieved. In addition, the 45° TFG works perfectly for both light emission and reception, enabling full-duplex optical wireless transmission. Utility of the 45° TFG in all-fiber laser beam steering for multi-user full duplex optical wireless communications has been verified in experiments. 1.4 m free-space full-duplex wireless transmission has been demonstrated with data rate up to 12 Gb/s per beam using 2.4 GHz bandwidth OFDM signals.
Habib, U. et al. (2018). Analog Radio-over-Fiber Supported Increased RAU Spacing for 60GHz Distributed MIMO employing Spatial Diversity and Multiplexing. Journal of Lightwave Technology [Online]. Available at: http://dx.doi.org/10.1109/JLT.2018.2832028.The improvements in coverage through spatial diversity and increased data rates through spatial multiplexing using a distributed Multiple-Input Multiple-Output (MIMO) system are important targets for future wireless communications. Here, the appropriate separation of Remote Antenna Units (RAUs) at several user locations in a millimeter-wave system is demonstrated. An analog Radio over Fiber (RoF) fronthaul is used to achieve flexible spacing of distributed RAUs and transports two Gb/s data streams over 2.2km of fiber and up to 8m of 60 GHz wireless transmission distance. A performance comparison is performed between Single-Input Single-Output (SISO) and MIMO operation using different antenna spacing and transmission distance. Results show that the wider RAU spacing enabled by the RoF distribution provides improved results at longer distances, for both spatial diversity and for spatial multiplexing. Verification of a method for measuring each channel coefficient individually and using subsequent MIMO processing on these coefficients, enables an extension to the results showing the feasibility of 30m indoor transmission.
Conference or workshop item
Mididoddi, C. et al. (2018). Ultrafast User Localization and Beam Steering in Optical Wireless Communication Using an In-Fibre Diffraction Grating. in: 2018 International Topical Meeting on Microwave Photonics (MWP). IEEE. Available at: https://doi.org/10.1109/MWP.2018.8552858.Wavelength-controlled laser beam steering has been successfully demonstrated for indoor optical wireless communications (OWC). Here we demonstrate ultrafast user localization (50 million scans per second) in OWC based on real-time wavelength monitoring. A separate time stretched pulsed laser source is introduced to implement ultrafast optical wavelength (hence optical beam) scanning. A dispersion unbalanced Mach-Zehnder interferometric configuration creates chirped encoding in stretch optical pulses. The reflected optical wavelength from a remote user carrying the location information of the user is detected by real-time instantaneous microwave frequency detection. This new approach facilitates simultaneous ultrafast user localization and data transmission at communication C-band. A proof-of-concept experiment is carried out to verify the proposed approach.
Yamaguchi, T. et al. (2017). Output power enhancement by optical pulse compression in photonic-based RF generation - Laser linewidth and phase noise of the RF output. in: IEICE General Conference.. Available at: https://www.awrcorp.com/news/events/event/2017-IEICE-general-conference.
Habib, U. et al. (2017). Demonstration of radio-over-fiber-supported 60 GHz MIMO using separate antenna-pair processing. in: 2017 International Topical Meeting on Microwave Photonics (MWP). IEEE. Available at: https://doi.org/10.1109/MWP.2017.8168700.Coverage at millimeter-wave (mmW) frequencies is a constraining bottleneck. Spatial diversity and spatial multiplexing multiple-input multiple-output (MIMO) improve performance over a spread of user locations and these can benefit from wider antenna spacing. Radio-over-Fiber (RoF) transport provides flexibility in deploying a number of widely-spaced Remote Antenna Units (RAUs) connected to the same Central Unit (CU). Hence, mmW systems with an integrated analog RoF fronthaul are strong candidates for use in future 5G networks. An approach to measure channel coefficients individually for MIMO processing has been demonstrated in a RoF transported 2×2 MIMO system at 60 GHz. Experimental results verify this approach through real 2×2 experiments.
Habib, U. et al. (2017). Performance Improvement for OFDM-RoF Transported 60 GHz System using Spatial Diversity and Multiplexing. in: 2017 IEEE International Conference on Communications Workshops. pp. 211-216. Available at: https://doi.org/10.1109/ICCW.2017.7962659.60 GHz system architectures with Radio over Fiber (RoF) transport and integrated transmitters/receivers provide a comprehensive solution for future mobile systems. Since 60 GHz communication relies on line-of-sight (LoS) conditions and narrow-beam antennas to compensate the high path-loss, it has limitations in terms of coverage for multiple user locations. In this paper, performance analysis of a 60 GHz integrated transmitter and receiver system supported by RoF transport has been performed experimentally at different user locations for up to 1.5m transmission distance. Extension of experimental results to prove feasibility for longer distances has been shown with a simulation model, whose results at various shorter distances have been benchmarked against the acquired experimental results at different user locations. A modified version of the Saleh Valenzuela channel has been used to model the millimeter wave (mmW) LoS indoor experimental environment. Furthermore, as a proof of concept, we present an experimental analysis demonstrating an improvement in performance of the proposed RoF based 60 GHz system using spatial diversity and multiplexing. Channel measurements at different transmitter/receiver locations and their processing have shown that an improvement (decrease from 12.5% to 10.5%) in Error Vector Magnitude (EVM) can be achieved using the Alamouti Space Time Block Coding algorithm. Then it has been shown that a two-fold data rate increase can be obtained by combining data from two transmitter locations using the Zero Forcing algorithm.
Murata, H. et al. (2017). Millimeter-wave communication system using photonic-based remote antennas for configurable network in dense user environment. in: IEEE Conference on Antenna Measurements & Applications (CAMA). IEEE, pp. 24-27. Available at: https://doi.org/10.1109/CAMA.2017.8273413.Photonic-based millimeter-wave communication systems combined with conventional wireless systems have been proposed for the application in dense user environments like a large football stadium. By utilizing a narrow beam antenna for millimeter-wave asymmetric links, effective communication channels can be obtained.
Wang, G. et al. (2017). Wavelength-controlled beam steering for optical wireless transmission using an in-fiber diffraction grating. in: 2017 Conference on Lasers and Electro-Optics.. Available at: http://dx.doi.org/10.1364/CLEO_SI.2017.SF1L.5.Passive beam steering for optical wireless transmission based on wavelength tuning using a novel in-fiber diffraction grating featuring compactness, high diffraction efficiency and inherent fiber-compatibility, is proposed and experimentally demonstrated for the first time.
Habib, U. et al. (2017). Radio-over-fiber-supported 60GHz multiuser transmission using leaky wave antenna. in: 2017 International Topical Meeting on Microwave Photonics (MWP). IEEE. Available at: https://doi.org/10.1109/MWP.2017.8305443.Simultaneous transmission to multiple users using a single-feed leaky-wave antenna (LWA) has been demonstrated. A composite signal transported through a Radio-over-Fibre (RoF) setup is upconverted to V-band frequencies and a LWA is used to direct different user data to their respective locations. An EVM analysis has been performed for two-user and three-user transmission for a range of angular locations. A performance analysis for user interference has been carried out by varying the signal spacing for 152 MHz and 305 MHz bandwidth OFDM signals, centered at 61.75 GHz after 4m of wireless transmission. The experimental results show degradation not only due to insufficient frequency spacing between the channels but also when the sidelobe interference of the neighboring data channels is higher.
Wang, G. et al. (2017). In-fibre diffraction grating based beam steering for full duplex optical wireless communication. in: International Topical Meeting on Microwave Photonics (MWP), 2017.. Available at: https://doi.org/10.1109/MWP.2017.8168644.A novel approach to achieve wavelength controlled optical beam steering using a 45° tilted fiber grating (TFG) for full-duplex indoor optical wireless transmission is proposed and experimentally demonstrated for the first time. The 45° TFG functions as an in-fiber passive diffraction device for wavelength steered light emission and reception, which enables full-duplex optical wireless transmission. The unique advantages of using an in-fiber TFG device for beam steering include high diffraction efficiency, low cost, compactness and inherent compatibility with existing fiber links. In a proof-of-concept experiment, free-space full-duplex transmission over 1.4 m with data rate of 9.6 Gb/s per beam has been demonstrated using 2.4 GHz bandwidth signals.
Gomes, N. et al. (2017). Support of Multi-antenna and Multi-user Systems Using Radio Over Fiber. in: Asia Communications and Photonics Conference 2017. OSA, p. Su4E.1. Available at: https://doi.org/10.1364/ACPC.2017.Su4E.1.Analog radio-over-fiber can efficiently support multi-antenna and multi-user techniques for future mobile communications. Experimental results demonstrate that the wider antenna separation that can be provided enhances multi-antenna scheme performance.
Habib, U. et al. (2016). Radio over fiber transport of mm-wave 2×2 MIMO for spatial diversity and multiplexing. in: Microwave Photonics (MWP), 2016 International Topical Meeting on. IEEE. Available at: http://dx.doi.org/10.1109/MWP.2016.7791280.DWDM-RoF transport and photonic generation of millimeter-wave MIMO signals has been demonstrated. Generation and modulation of independent data streams over different wavelengths provides allocation flexibility and centralization. EVM results show that this low-cost technique provides antenna diversity/multiplexing gain for STBC-Alamouti and Zero-Forcing algorithms based OFDM-MIMO.
Habib, U. et al. (2018). Radio-over-Fiber-supported Millimeter-wave Multiuser Transmission with Low-Complexity Antenna Units. in: IEEE International Topical Meeting on Microwave Photonics.A system for serving a large number of users at millimeter-wave (mmW) frequencies using a single Radio Frequency (RF) chain is presented. A single Remote Antenna Unit (RAU) supported by Radio over-Fiber transport is used to transmit multiple 60GHz band signals to various users located at different spatial locations using the beamsteering characteristics of a Leaky Wave Antenna (LWA). Error Vector Magnitude analysis has been performed for each user signal up to a maximum of seven users per RF chain with wireless transmission over 2m. A performance comparison for different user-signal frequency spacings has been provided to understand the limitations of the system and results show that the proposed system design with the LWA performs better than systems using waveguide and horn
antenna transmitters. A realization to double the number of served users is also presented which shows that up to 10 users can be served using half region of the LWA, with each user transmitting
1Gb/s data rate, delivering an aggregate data rate of 10Gb/s.