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Publicações

Publicações por CTM

2008

CommGate: a communal residential gateway

Autores
Moreira, R; Mamede, J; Oliveira, B; Silva, V; Silva, L; Ruela, J;

Publicação
2008 5TH IEEE CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE, VOLS 1-3

Abstract
Currently, the bandwidth utilization of residential broadband links is highly inefficient. Providing the means for sharing these links will increase the total bandwidth and reduce the fixed costs per client thus promoting the use of Internet services. This paper proposes a low cost communal residential gateway for sharing and remotely managing broadband access links. We first identify and characterize existing problems on residential asymmetric link sharing scenarios and then propose and evaluate the CommGate prototype that overcomes these problems. This solution contributes to an efficient broadband link sharing, a cost breakdown and an increasing Internet access dissemination, particularly in developing countries.

2008

A protocol for event distribution in next-generation dynamic networks

Autores
Pinho, C; Ruela, J; Pentikousis, K; Kappler, C;

Publicação
2008 NEXT GENERATION INTERNET NETWORKS AND 4TH EURONGI CONFERENCE ON NEXT GENERATION INTERNET NETWORKS, PROCEEDINGS

Abstract
With the increasing number of devices carried by users and the emergence of more dynamic network scenarios, new solutions have to be developed to support ubiquitous communications. The need for dynamic and transparent auto-configuration and adaptation of applications, devices and networks of devices to a wide variety of events is one of the major challenges. This paper presents a protocol to be used with notification systems, to support the registration, subscription and distribution of generic events among heterogeneous and independent entities, thus addressing the requirements of future communication scenarios.

2008

EBG PIFA Design for WLAN Applications

Autores
Luo, Q; Salgado, HM; Pereira, JR;

Publicação
2008 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, VOLS 1-9

Abstract
This paper proposes a new low profile dual band WLAN Planar inverted-F antenna (PIFA) by using Electromagnetic Band-Gap (EBG) material as ground plane. The total thickness of this antenna is only 4 mm, which is half of the height when a normal perfect electric conductor (PEC) ground plane is used. The backward radiation ratio is also reduced as the existence of EBG. Moreover, the bandwidth for the 5 GHz; band is increased by 10 times compared to the reference antenna. This EBG PIFA is built on the ground plane with size of 40x62 mm, which is suitable for most of the mobile devices.

2008

Dual-band antenna design using an EBG artificial magnetic conductor ground plane

Autores
Luo, Q; Salgado, HM; Moura, AM; Pereira, JR;

Publicação
2008 Loughborough Antennas and Propagation Conference, LAPC

Abstract
This work studies dual-band EBG structures used as an Artificial Magnetic Conductor (AMC) ground plane for WLAN co-planar antenna to achieve a low profile structure. From the simulation results, the EBG surface geometry with Jerusalem Cross (JCSS) slot has been chosen in this study. A dual band prototype operating at 2.4 and 5.2 GHz has been implemented and tested. The results show that the EBG antenna can work properly at desired frequency bands with improved gain and reduced back lobe. ©2008 IEEE.

2008

Joint Mitigation of Optical Impairments and Phase Estimation in Coherent Optical Systems

Autores
Pessoa, LM; Salgado, HM; Darwazeh, I;

Publicação
2008 DIGEST OF THE LEOS SUMMER TOPICAL MEETINGS

Abstract
The electrical compensation of chromatic dispersion (CD) and polarization mode dispersion (PMD) in a coherent optical system exploiting polarization multiplexing is discussed in this paper. The benefits of combining a phase estimation algorithm with a decision directed least-mean-square equalizer in a feedback configuration is reported.

2008

Optimum Receivers for Non-Linearly Distorted OFDM Signals in Wireless-over-Fiber Applications: Impact of Antenna Noise

Autores
Oliveira, JMB; Rodrigues, MRD; Salgado, HM;

Publicação
2008 IEEE INTERNATIONAL CONFERENCE ON ULTRA-WIDEBAND, VOL 2, PROCEEDINGS

Abstract
In this paper, we study the effect of uplink wise on the optimality of the receiver structure proposed in [1][2]. This optimum receiver is composed by a demodulator that extracts a set of sufficient statistic, and by an ML detector that uses the demodulator output to estimate the original data, We concentrate on Intensity Modulation/Direct Detection (IM/DD) Radio-over-Fiber (RoF) uplink system when OFDM signals suffer from noise generated by the antenna and photodiode and from nonlinear distortion. The results show that for small and medium modulalion index values, the uplink noise maintains its Gaussian distribution and the optimum receiver still outperforms the conventional.

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