Optical Wireless Integration Research Articles

Probabilistically shaped 64QAM OFDM signal transmission in a heterodyne coherent detection system

Abstract We experimentally demonstrated the transmission of uniform and probabilistically-shaped (PS) 64-ary quadrature amplitude modulated (64QAM) orthogonal frequency division multiplexing (OFDM) signal in a heterodyne coherent detection system. In the demonstrated system, the signal can be transmitted over 22 km single-mode optical fiber and 1, 3, 5, 13 m wireless link. To the best of our knowledge, this is the first time that PS-64QAM OFDM signal is transmitted in an optical wireless integration system. Heterodyne coherent detection is employed at the receiving end in this system.

Multidimensional Convergence in Future 5G Networks

Future 5G services are characterised by unprecedented need for high rate, ubiquitous availability, ultra-low latency and high reliability. The fragmented network view that is widespread in current networks will not stand the challenge posed by next generations of users. A new vision is required, and this paper provides an insight on how network convergence and application-centric approaches will play a leading role towards enabling the 5G vision. The paper, after expressing the view on the need for an end-to-end approach to network design, brings the reader into a journey on the expected 5G network requirements and outlines some of the work currently carried out by main standardisation bodies. It then proposes the use of the concept of network convergence for providing the overall architectural framework to bring together all the different technologies within a unifying and coherent network ecosystem. The novel interpretation of multi-dimensional convergence we introduce leads us to the exploration of aspects of node consolidation and converged network architectures, delving into details of optical-wireless integration and future convergence of optical data centre and access-metro networks. We then discuss how ownership models enabling network sharing will be instrumental in realising the 5G vision. The paper concludes with final remarks on the role SDN will play in 5G and on the need for new business models that reflect the application-centric view of the network. Finally, we provide some insight on growing research areas in 5G networking.

Optical wireless integration based on phase modulator down-conversion for W-band QPSK signal delivery

We demonstrate one optical wireless integration system for 44Gb/s polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal down-conversion based on phase modulators. 2×100km single-mode fiber-28 (SMF-28) fiber transmission and 3m wireless delivery at 88GHz W-band are realized in our experiment. We also compare the different modulation formats with the same bit rate transmission in this optical wireless integration link.

2 × 2 multiple-input multiple-output optical-wireless integration system based on optical independent-sideband modulation enabled by an in-phase/quadrature modulator.

We propose a novel and simple 2×2 multiple-input multiple-output (MIMO) optical-wireless integration system, in which optical independent-sideband modulation enabled by an in-phase/quadrature (I/Q) modulator, instead of optical polarization multiplexing, is used to assist the simultaneous generation of two wireless millimeter-wave (mm-wave) signals. Software-based digital signal processing is used to generate the driving signal for the I/Q modulator, the output of which is two independent single-sideband optical vector signals located at two sides of a large central optical carrier. Based on our proposed 2×2 MIMO optical-wireless integration system, we experimentally demonstrate the simultaneous generation and 2×2 MIMO wireless delivery of two independent 40-GHz quadrature-phase-shift-keying (QPSK) wireless mm-wave signals. Each 40-GHz QPSK wireless mm-wave signal can carry up to 4-Gbaud transmitter data with a bit-error ratio less than the hard-decision forward-error-correction threshold of 3.8×10^-3.

Review of physical layer networking for optical-wireless integration

We present a review of physical networking options and enabling system technologies for efficient unification of optical and wireless access backhaul infrastructure. Different physical layer integration architectures are reviewed in conjunction with the possible wireless signal transport schemes. We also review some of our research work as one possible physical layer integration technique using RF-overlay passive optical network incorporating an optical tandem single sideband (OTSSB) modulation scheme for simultaneous transport of wired and wireless signals.

Optical-wireless-optical full link for polarization multiplexing quadrature amplitude/phase modulation signal transmission

We propose and experimentally demonstrate an optical wireless integration system at the Q-band, in which up to 40 Gb/s polarization multiplexing multilevel quadrature amplitude/phase modulation (PM-QAM) signal can be first transmitted over 20 km single-mode fiber-28 (SMF-28), then delivered over a 2 m 2 × 2 multiple-input multiple-output wireless link, and finally transmitted over another 20 km SMF-28. The PM-QAM modulated wireless millimeter-wave (mm-wave) signal at 40 GHz is generated based on the remote heterodyning technique, and demodulated by the radio-frequency transparent photonic technique based on homodyne coherent detection and baseband digital signal processing. The classic constant modulus algorithm equalization is used at the receiver to realize polarization demultiplexing of the PM-QAM signal. For the first time, to the best of our knowledge, we realize the conversion of the PM-QAM modulated wireless mm-wave signal to the optical signal as well as 20 km fiber transmission of the converted optical signal.

Faster than fiber: over 100-Gb/s signal delivery in fiber wireless integration system

We summarize several different approaches for the realization of large capacity (>100Gb/s) fiber wireless integration system, including optical polarization-division-multiplexing (PDM) combined with multiple-input multiple-output (MIMO) reception, advanced multi-level modulation, optical multi-carrier modulation, electrical multi-carrier modulation, antenna polarization multiplexing and multi-band multiplexing. These approaches can effectively reduce the signal baud rate as well as the required bandwidth for optical and electrical devices. We also investigate the problems, such as wireless multi-path effect due to different wireless transmission distance, existing in the large capacity fiber wireless integration system. We demonstrate these problems can be effectively solved based on advanced digital-signal-processing (DSP) algorithms including classic constant modulus algorithm (CMA). Moreover, based on the combination of these approaches as well as advanced DSP algorithms, we have successfully demonstrated a 400G fiber wireless integration system, which creates a capacity record of wireless delivery and ushers in a new era of ultra-high bit rate (>400Gb/s) optical wireless integration communications at mm-wave frequencies.

A 400G optical wireless integration delivery system

We experimentally demonstrate a record 400G optical wireless integration system simultaneously delivering 2 × 112 Gb/s two-channel polarization-division-multiplexing 16-ary quadrature amplitude modulation (PDM-16QAM) signal at 37.5 GHz wireless carrier and 2 × 108 Gb/s two-channel PDM quadrature phase shift keying (PDM-QPSK) signal at 100 GHz wireless carrier, adopting two millimeter-wave (mm-wave) frequency bands, two orthogonal antenna polarizations, multiple-input multiple-output (MIMO), photonic mm-wave generation and advanced digital signal processing (DSP). In the case of no fiber transmission, the bit error ratios (BERs) for both the 112 Gb/s PDM-16QAM signal after 1.5 m wireless delivery at 37.5 GHz and the 108 Gb/s PDM-QPSK signal after 0.7 m wireless delivery at 100 GHz are below the pre-forward-error-correction (pre-FEC) threshold of 3.8 × 10(-3). To our knowledge, this is the first demonstration of a 400G optical wireless integration system in mm-wave frequency bands and also a capacity record of wireless delivery.

Investigation of interference in multiple-input multiple-output wireless transmission at W band for an optical wireless integration system

We experimentally investigate the interference in multiple-input multiple-output (MIMO) wireless transmission by adjusting the relative locations of horn antennas (HAs) in a 100 GHz optical wireless integration system, which can deliver a 50 Gb/s polarization-division-multiplexing quadrature-phase-shift-keying signal over 80 km single-mode fiber-28 and a 2×2 MIMO wireless link. For the parallel 2×2 MIMO wireless link, each receiver HA can only get wireless power from the corresponding transmitter HA, while for the crossover ones, the receiver HA can get wireless power from two transmitter HAs. At the wireless receiver, polarization demultiplexing is realized by the constant modulus algorithm (CMA) in the digital-signal-processing part. Compared to the parallel case, wireless interference causes about 2 dB optical signal-to-noise ratio penalty at a bit-error ratio (BER) of 3.8×10(-3) for the crossover cases if similar CMA taps are employed. The increase in CMA tap length can reduce wireless interference and improve BER performance. Furthermore, more CMA taps should be adopted to overcome the severe wireless interference when two pairs of transmitter and receiver HAs have different wireless distances.

Next generation optical-wireless converged network architectures

This article provides a comprehensive analysis on implementing the next-generation optical-wireless integration architectures. The different approaches to implementing a complete fixed-mobile converged network that ensures desired quality of service for various applications are explored. This discussion is specifically focused on LTE-10GEPON integration networks where passive optical networks are used as the backhaul to LTE. Special attention is given to address the issue of providing proper means to enable intercommunication between neighboring base stations, which is one of the crucial considerations in next-generation wireless networks. We propose potential 10GEPON-LTE converged network architectures and comparatively analyze the benefits gained from each of the integration architectures by elaborating on the operational and control structures. Our performance analysis provides insight into QoS-rich next-generation optical-wireless converged networks.

SuperMAN: Optical-wireless integration of RPR and WiMAX

This paper introduces a novel fiber-wireless (FiWi) network architecture, called SuperMAN, and investigates the optical-wireless integration of a resilient packet ring (RPR) and WiMAX networks. We propose a novel hierarchical integrated scheduling algorithm that significantly improves the throughput-delay performance and triple-play quality-of-service support for fixed and mobile users. By means of extensive simulations we show in a benchmark comparison that the proposed hierarchical scheduler clearly outperforms the widely deployed weighted fair queuing (WFQ) scheduler in terms of mean aggregate throughput and mean delay as well as robustness for voice, video, and data traffic under realistic wireless channel conditions.