Performance improvement and cost reduction techniques for radio over fiber communications

Advanced cost reduction and performance improvement techniques conceived for Radio Over Fiber (ROF) communications are considered. ROF techniques are expected to form the backbone of the future 5G generation of wireless networks. The achievable link performance and the associated deployement cost constitute the most salient metrics of a ROF architecture. In this paper, we commence by providing a rudimentary overview of the ROF architecture and then elaborate on ROF techniques designed for improving the attainable system performance. We conclude by describing the ROF techniques conceived for reducing the ROF system installation costs

Silicon photonics traveling wave photodiode with integrated star coupler for high-linearity mm-wave applications

Next-generation wireless communication will require increasingly faster data links. To achieve those higher data rates, the shift towards mmWave frequencies and smaller cell sizes will play a major role. Radio-over-Fiber has been proposed as a possible architecture to allow for this shift but is nowadays typically implemented digitally. as CPRI (Common Public Radio Interface). Centralization will be important to keep next-generation architectures cost-effective and therefore shared optical amplification at the central office could be preferable. Unfortunately. limited power handling capabilities of photodetectors still hinder the shift towards centralized optical amplification. Traveling wave photodetectors (TWPDs) have been devised to allow for high-linearity, high-speed opto-electronic conversion. In this paper, an architecture is discussed consisting of such a TWPD implemented on the iSiPP25G silicon photonics platform. A monolithically integrated star coupler is added in the design to provide compact power distribution while preserving the high linearity of the TWPD. The traveling wave structure (using 16 photodetectors) has a measured 3 dB bandwidth of 27.5 GHz and a fairly flat S-21 up to 50 GHz (less than 1 dB extra loss). Furthermore, the output referred third-order intercept point at 28 GHz, is improved from -1.79 dBm for a single Ge photodiode to 20.98 dBm by adopting the traveling wave design. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Analysis of system capacity and spectral efficiency of fixed-grid network

In this article, the performance of a fixed grid network is examined for various modulation formats to estimate the system's capacity and spectral efficiency. The optical In-phase Quadrature Modulator structure is used to build a fixed grid network modulation, and the homodyne detection approach is used for the receiver. Data multiplexing is accomplished using the Polarization Division Multiplexed technology. 100 Gbps, 150 Gbps, and 200 Gbps data rates are transmitted under these circumstances utilizing various modulation formats. Various pre-processing and signal recovery steps are explained by using modern digital signal processing systems. The achieved spectrum efficiencies for PM-QPSK, PM-8 QAM, and PM-16 QAM, respectively, were 2, 3, and 4 bits/s/Hz. Different modulation like PM-QPSK, PM-8-QAM, and PM-16-QAM each has system capacities of 8-9, 12-13.5, and 16-18 Tbps and it reaches transmission distances of 3000, 1300, and 700 kilometers with acceptable Bit Error Rate less than equal to 2*10-3 respectively. Peak optical power for received signal detection and full width at half maximum is noted for the different modulations under a fixed grind network

Novel Vestigial Sideband Modulation Scheme to Enhance the SNR in Radio Over Fiber Systems

The optical single sideband (OSSB) scheme is a common choice in radio over fiber system for compensating chromatic dispersion (CD) but it suffers from low signal to noise ratio (SNR).We present the novel technique for SNR improvement using unequal sideband intensity based modulation scheme, we name it optical vestigial sideband modulation scheme (OVSB). To analyze such scheme we use the series Mach-Zehnder modulator (MZM) and phase modulator (PM) configuration. In this configuration by operating MZM at quadrature point and properly tuning the PM index the individual intensity of the first order sidebands and higher order harmonics can be controlled independent to each other.The optimum operating point of PM for maximizing the SNR can be identified by reducing the harmonic distortion and increasing the first order sidebands power. We experimentally validated the proposed OVSB scheme generation method and provide its theoretical proof. We evaluate the symbol error rate (SER) performance using 4QAM signal for OSSB and OVSB and show the improved performance of OVSB scheme compared to OSSB scheme. We also discuss the harmonic distortion behavior of the series MZM and PM configuration

Sistemas de radio sobre fibra y redes 5G: perspectiva y aplicaciones

This document presents an exhaustive investigation of the advances that Radio over Fiber Systems have had worldwide in recent years, knowing in a better way the applications and generalities of said systems. Likewise, this review also contains information about the designs of an optical communication system, 5G networks, among others. Additionally, Radio over Fiber systems have had a great impact today due to their multiple benefits, since they have an attenuation of 0.2 dB/km. Finally, this article allows us to observe the need to cover the lines of research related to this subject, in order to be at the forefront of the world's technological evolution.Este documento presenta una investigación exhaustiva de los avances que han tenido los sistemas de radio sobre fibra en el ámbito mundial en los últimos años, conociendo de una mejor manera sus aplicaciones y generalidades. Esta revisión también contiene información sobre los diseños de un sistema de comunicación óptico, redes 5G, entre otros. Adicionalmente, estos sistemas de radio han tenido un gran impacto en la actualidad a causa de sus múltiples beneficios, ya que cuentan con una atenuación de 0,2 dB/km. Finalmente, este artículo permite observar la necesidad de cubrir las líneas de investigación referentes a esta temática, para estar a la vanguardia en la evolución tecnológica del mundo