Silvia Pato

A Comparison of Radio Over Fiber Link Types for the Support of Wideband Radio Channels

Three radio over fiber link types are compared to assess their relative performance for the optical transmission of next generation wireless signals having multiple wideband radio channels with high-level modulation. These links differ in their choice of modulation device; either a directly modulated laser (DML) or external modulation using a Mach-Zehnder modulator (MZM) or a reflective semiconductor optical amplifier (RSOA). The DML and RSOA link types are shown to suffer minimal degradation of the uplink wireless range compared to the baseline value without an optical link, using optimum components in terms of cost and performance. The optimum technology depends on the relative merits of simplicity (DML) or optical network architecture flexibility (RSOA).

All-Optical Burst-Mode Power Equalizer Based on Cascaded SOAs for 10-Gb/s EPONs

This letter proposes a new power equalization scheme based on cascaded semiconductor optical amplifiers, for 10-Gb/s ethernet passive optical networks with uneven topology. For networks with a large number of subscribers, the proposed equalization scheme enables a 16-dB reduction of the receiver dynamic range.

A comparison of remote radio head optical transmission technologies for next generation wireless systems

A performance and cost comparison is made between analogue and digital optical transmission technologies for linking remote radio heads to digital base stations for future wireless systems with wide channel bandwidth and multiple MIMO channels.

Impact of add/drop port utilization flexibility in DWDM networks [Invited]

Optical transport networks are at the turning point from providing semi-permanent connections to being engineered to efficiently support dynamic optical connection services. Vital to this transition is the availability of node architectures that improve the flexibility of add/drop port utilization, thereby enabling the transponder connected to a port to be reused to realize connections with different wavelength channels or using different input/output fiber links (directions). This paper assesses the network-wide blocking performance provided by node architectures with different degrees of freedom for port reuse. The performance assessment not only clearly highlights the relevance of maximizing the chances of transponder sharing in transport networks, but also shows that the network topology determines which of the degrees of freedom for port reuse is more relevant.

Fiber Optic Networks for Distributed Radio Architectures: FUTON Concept and Operation

The growing importance of wireless communications has been driving the research and development of advanced network architectures to enable the cost-effective support of large numbers of users at very high data rates. In this context, the FUTON project aims to fulfil the objectives of the so-called 4th Generation (4G) wireless communications through an innovative Distributed Antenna System (DAS) with centralized signal processing. An overview of the FUTON concept is presented in this paper, with emphasis on the optical link design for radio-over-fiber communication providing the virtual-MIMO functionalities between multiple remote antenna units with a centralized processing site. Also, the units being fabricated for the final demonstration are described, and some preliminary measurements are presented.

Comparative evaluation of fibre-optic architectures for next-generation distributed antenna systems

The growing relevance of wireless communications has been driving the research and development of advanced network architectures to enable the cost-effective support of large numbers of users at very high data rates. In this context, the FUTON project aims to fulfil the objectives of the so-called 4th Generation (4G) through an innovative Distributed Antenna System (DAS) with centralized signal processing. The DAS is best supported with optical fibre as the transmission medium, consequently requiring an analysis of the most suitable fibre-optic architecture to interconnect its network elements. This paper compares candidate fibre-optic architectures for FUTON, or similar DAS, in terms of their network elements, power budget and relative cost.

On supporting radio over fiber and passive optical network systems with a common fiber plant: Compatibility aspects

In view of the current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence issues between both types of access networks. Therefore, this paper analyzes compatibility aspects of supporting radio signals over a passive optical infrastructure, which must be accounted for to enable the coexistence of fixed and radio access systems over a common fiber plant.

Quantifying the impact of DWDM nodes with flexible add/drop port utilization for dynamic connection setup

DWDM transport networks are evolving towards dynamic setup/rerouting of optical connections. This paper quantifies the impact of optical node architecture and traffic variability on the network blocking probability and transponder count requirements.

Capacity prospects of future high density metro-access networks

One of the most commonly accepted trends in access networks evolution is merging access and metro aggregation systems, under the premise of enabling the cost-effective support of a larger number of users and/or an extended geographic coverage using a single physical infrastructure. This network architecture extends the reach of the transparent link between the end user and metro networks, providing savings in terms of the aggregation equipment typically deployed between the access and metro aggregation segment. However, bridging access and metro aggregation networks requires a careful dimensioning taking into account both the system limitations and the need to guarantee a low cost per user supported. This paper addresses the capacity boundaries of a metro-access system, formed by multiple tree-based high density access networks interconnected transparently via a high capacity metro ring.

Impact of Mode-Partition Noise in the Performance of 10 Gbit/s Ethernet Passive Optical Networks

The enormous success of Ethernet passive optical network (EPON) deployment has been inciting the development of upgrades for this system, namely the data rate upgrade. In these upgraded next generation access networks, low-cost and simplicity should play a fundamental role, and so the use of low cost multimode laser sources should be considered. However, impairments such as Mode-Partition Noise (MPN) will arise and will affect the performance of the network. This paper presents an evaluation of the impact of MPN in 10 Gbit/s EPONs that employ multimode laser sources. It is shown that MPN may have a severe impact, but the use of Forward Error Correction (FEC) is considered as a way to mitigate this effect.