Microwave photonics, which brings together the worlds of radiofrequency engineering and optoelectronics, has attracted great interest from both the research community and the commercial sector over the past 30 years and is set to have a bright future. The technology makes it possible to have functions in microwave systems that are complex or even not directly possible in the radiofrequency domain and also creates new opportunities for telecommunication networks. Here we introduce the technology to the photonics community and summarize recent research and important applications.

Microwave photonics combines two worlds

The hybrid wireless-optical broadband-access network (WOBAN) is a promising architecture for future access networks. Recently, the wireless part of WOBAN has been gaining increasing attention, and early versions are being deployed as municipal access solutions to eliminate the wired drop to every wireless router at customer premises. This architecture saves on network deployment cost because the fiber need not penetrate each end-user, and it extends the reach of emerging optical-access solutions, such as passive optical networks. This paper first presents an architecture and a vision for the WOBAN and articulates why the combination of wireless and optical presents a compelling solution that optimizes the best of both worlds. While this discussion briefly touches upon the business drivers, the main arguments are based on technical and deployment considerations. Consequently, the rest of this paper reviews a variety of relevant research challenges, namely, network setup, network connectivity, and fault-tolerant behavior of the WOBAN. In the network setup, we review the design of a WOBAN where the back end is a wired optical network, the front end is managed by a wireless connectivity, and, in between, the tail ends of the optical part [known as optical network unit (ONU)] communicate directly with wireless base stations (known as ldquogateway routersrdquo). We outline algorithms to optimize the placement of ONUs in a WOBAN and report on a survey that we conducted on the distribution and types of wireless routers in the Wildhorse residential neighborhood of North Davis, CA. Then, we examine the WOBAN's routing properties (network connectivity), discuss the pros and cons of various routing algorithms, and summarize the idea behind fault-tolerant design of such hybrid networks.

Hybrid Wireless-Optical Broadband-Access Network (WOBAN): A Review of Relevant Challenges

We have experimentally demonstrated a full-duplex radio-over-fiber system using a single light source at central station (CS). Optical carrier suppression modulation scheme was employed to generate 40-GHz optical millimeter wave and up-convert the baseband signal simultaneously at CS for downlink transmission while the same optical carrier was reused at base station for uplink connection. The bidirectional full-duplex 2.5-Gb/s data was successfully transmitted over 40-km standard single-mode fiber (SMF-28) for both upstream and downstream channels with less than 2-dB power penalty. This system shows simple cost-efficient configuration and good performance over long-distance delivery

A full-duplex radio-over-fiber system based on optical carrier suppression and reuse

We have theoretically investigated the transmission performance of the optical millimeter-waves (mm-waves) generated using intensity modulation via a Mach-Zehnder modulator, with the double and single sidebands (DSB and SSB) and optical carrier suppression (OCS) schemes. According to our theoretical analysis, fiber chromatic dispersion leads to fading effect and time shifting of the codes; therefore, signals are greatly degraded. Of all signals, DSB optical mm-wave suffers from both the fading effect and the time shifting of the codes. However, the optical mm-waves generated by SSB and OCS schemes are immune to the fading effect, while the time shifting of the codes limits their transmission distance. Experimental and simulation results confirm the theoretical analysis.

Fiber Dispersion Influence on Transmission of the Optical Millimeter-Waves Generated Using LN-MZM Intensity Modulation

In recent years considerable attention has been devoted to the merging of radio frequency and optical fiber technologies aiming to the distribution of millimeter-wave (mm-wave) signals. This effort has given birth to the field of Radio over Fiber (RoF) technologies and systems. This sort of systems have a great potential to support secure, cost-effective, and high-capacity vehicular/mobile/wireless access for the future provisioning of broadband, interactive, and multimedia wireless services. In this paper we present a comprehensive review of mm-wave frequency RoF systems. In our integral approach, we identified the most important figures of merit of an RoF system, which is divided into three main subsystems: Central Station (CS), Optical Distribution Network (ODN) and Base Station (BS). In each subsystem, the most promising technologies are classified: downlink transmission techniques at the CS, ODN architectures, and optical configurations of the BS. The impact of technology choice on the overall system performance is discussed, and the figures of merit are studied and used to assess the subsystem's performance. Finally, we suggest technological opportunities and future developments that should be attracting the attention of researchers and developers.

Millimeter-Wave Frequency Radio over Fiber Systems: A Survey

We propose to use a supercontinuum (SC) for a low-phase-noise multiwavelength light source in wavelength-division-multiplexing (WDM) millimeter-waveband (mm-waveband) radio-on-fiber (RoF) systems. We demonstrate the generation of low-phase-noise 60-GHz-band RoF signal. We also demonstrate the generation of two-channel WDM 60-GHz-band RoF signals and the transmission of the signals over a 25-km standard single-mode fiber (SMF) using photonic upconversion. The single multiwavelength light source can be shared with a number of users and simplifies the system configuration, which would allow the realization of high-reliability as well as low-cost RoF systems. Finally, the RoF network capacity with a single SC light source is estimated to be over 10 000 channels when the spectrum of the SC light source is fully utilized.

Wavelength-division-multiplexed Millimeter-waveband radio-on-fiber system using a supercontinuum light source

We qualitatively evaluate for the first time phase-noise characteristics of radio-frequency carriers of a supercontinuum generator and prove to be promising as the multiwavelength light source for wavelength-division-multiplexed millimeter-wave-band radio-on-fiber systems.

Characterizations of supercontinuum light source for WDM millimeter-wave-band radio-on-fiber systems

We demonstrate for the first time the full-duplex transmission of 25-GHz spacing dense wavelength-division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (RoF) system using a supercontinuum (SC) light source and optical frequency interleaving technique. In the proposed scheme, filtering response of the arrayed waveguide gratings for demultiplexer and multiplexer is used for suppression of undesired optical sidebands. All the 25-GHz spacing SC modes are used for downlink transmission with photonic up-conversion. The uplink RoF signals are generated with photonic down-conversion from the reused downlink signals. The up- and downlinks 60-GHz-band 156-Mbps RoF signals were simultaneously transmitted over 25-km standard single-mode fibers with error-free and 0.5 dB power penalties

Full-Duplex 25-GHz Spacing DWDM MM-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source and Arrayed-Waveguide-Grating Filters

We propose to use a supercontinuum light source for WDM millimeter-wave-band radio-on-fiber (ROF) systems 2-channel WDM 60-GHz-band ROF signals are generated and transmitted over 25-km standard single mode fiber using a photonic up-conversion technique

/pdf/wdm-mm-wave-band-radio-on-fiber-system-using-single-ky5rnwoi6a.pdf

WDM mm-wave-band radio-on-fiber system using single supercontinuum light source in cooperation with photonic up-conversion

We demonstrate a full-duplex WDM millimeter-wave-band radio-on-fiber (RoF) system using a supercontinuum (SC) light source For downlink transmission, the periodic nature of arrayed waveguide grating, where the period is free spectral range, is used for utilizing the full bandwidth of the SC light source Half of the SC output modes are used for uplink transmission with photonic downconversion These techniques are effective to use a wealth of optical frequency resources from the SC light source Two-channel downlink and one-channel uplink 60-GHz band RoF signals were simultaneously transmitted over 25-km standard single-mode fiber with error-free and no noticeable power penalty

https://www1.doshisha.ac.jp/~toda/Publications/2-53.pdf

T. Nakasyotani

Papers

Wavelength-division-multiplexed Millimeter-waveband radio-on-fiber system using a supercontinuum light source

Characterizations of supercontinuum light source for WDM millimeter-wave-band radio-on-fiber systems

Full-Duplex 25-GHz Spacing DWDM MM-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source and Arrayed-Waveguide-Grating Filters

WDM mm-wave-band radio-on-fiber system using single supercontinuum light source in cooperation with photonic up-conversion

A Full-duplex WDM Millimeter-Wave-Band Radio-on-Fiber System Using A Supercontinuum Light Source