Spread spectrum technique to improve the performance of radio over fibre for microcellular GSM networks

This paper presents a GSM-specific assessment of the performance of a radio over fibre link between a remote antenna unit and GSM base station. The intermodulation distortion (IMD) has been analysed for a system using the subcarrier multiplexing (SCM). A novel technique using direct sequence spread spectrum is proposed to minimize the IMD by decreasing the signal amplitude prior to a direct modulation of a laser diode. The results show that the optical fibre microcellular is outperforming the full wireless system

High Speed Wireless Internet Access: Combination of MPLS and BRAN HIPERLAN/2 technologies

This paper discusses the provision of High Speed Wireless Internet Access. It combines the MPLS technology for the core network and the next generation wireless BRAN HIPERLAN2 technology for the access part. The paper focuses on the interworking of MPLS within the HIPERLAN/2, through the design of a Convergence Layer. Two cases have been examined. In the first one, the AP is MPLS capable running a "light" version of the LDP protocol whereas in the second one MPLS is terminated at the edge router. The advantages and disadvantages of both approaches have been presented. Furthermore, the employment of MPLS to provide mobility management functionalities has been addressed. Two mobility management schemes have been examined. In the first one, MPLS is combined with Mobile IP to alleviate the problems of IP-in-IP encapsulation and triangular routing. In the second one, MPLS extensions have been proposed to provide mobility management services in an MPLS Administrative Domain

Finite element analysis of an optical fibre electric field sensor using piezoelectric polymer coating

A novel approach for analysing an optical fibre electric field sensor by using the finite element method is presented. A singlemode optical fibre carrying a transversely poled piezoelectric poly(vinylidene fluoride) polymer coating was successfully modelled by using three-dimensional analysis. The response of the optical fibre electric field sensor was determined over a wide frequency range from 100 Hz to 50 MHz. The modelling predicts a phase shift of 0.019 rad V-1 m(-1) in the low frequency (axially unconstrained) region and 0.00082 rad V-1 m(-1) in the high frequency (axially constrained) region. At frequencies higher than 7 MHz the optical response is dominated by radial resonances of the fibre-jacket composite. Good agreement exists between the resonance peaks predicted by the simulation and those theoretically calculated using composite theory