Abstract
The so-called "phase delay tracking" attempts to estimate the effects of the turbulence on the phase of the interferograms in order to numerically cophase the measured complex visibilities and to coherently integrate them. This is implemented by the "coherent fringe analysis" of MIDI instrument1 but has only been used for high SNR data. In this paper, we investigate whether the sensitivity of this technique can be pushed to its theoretical limits and thus applied to fainter sources. In the general framework of the maximum likelihood and exploiting the chromatic behavior of the turbulence effects, we propose a global optimization strategy to compute various estimators of the differential pistons between two data frames. The most efficient estimators appear to be the ones based on the phasors, even though they do not yet reach the theoretical limits.

Abstract
Two simulated astronomical objects (a star cluster, and a young stellar object) were mock observed with the VLTI for different array configurations and instruments, and their images reconstructed and compared. The aim of the work is to infer when/if phase referencing with less telescopes is a better choice over closure phases with more telescopes. Three scenarios were put under scrutiny: Phase Referencing (PhR) with 2 telescopes vs Closure Phase (CPh) with 3 telescopes, PhR with 3 telescopes vs CPh with 4 telescopes, and PhR with 4 telescopes vs CPh with 6 telescopes. The number of nights is kept fixed for a given PhR vs CPh configuration. The UV-coverage was improved for the PhR case, by uniformly paving the (u, v) plane while keeping fixed the total number of sampled spatial frequencies. For the majority of the configurations, the results point to comparable performances of phase referencing and closure phases, when the UV-space is judiciously chosen.

Abstract
IEEE 802.11-based Stub Wireless Mesh Networks (WMNs) are a cost-effective and flexible solution to extend wired network infrastructures. Yet, they suffer from two major problems: inefficiency and unfairness. A number of approaches have been proposed to tackle these problems, but they are too restrictive, highly complex, or require time synchronization and modifications to the IEEE 802.11 MAC. PACE is a simple multi-hop scheduling mechanism for Stub WMNs overlaid on the IEEE 802.11 MAC that jointly addresses the inefficiency and unfairness problems. It limits transmissions to a single mesh node at each time and ensures that each node has the opportunity to transmit a packet in each network-wide transmission round. Simulation results demonstrate that PACE can achieve optimal network capacity utilization and greatly outperforms state of the art CSMA/CA-based solutions as far as goodput, delay, and fairness are concerned.

Abstract
The back propagation algorithm is one of the best methods known for simultaneous linear and nonlinear impairment mitigation in long-haul fibre-optic links. Better understanding the full potential of such algorithm is key to improve the capacity of future links, whose design is likely to depend on the algorithm performance under different link configurations. In this paper, we carry out a novel and pertinent comparison in terms of the computational complexity requirements of both symmetric and asymmetric back-propagation implementation approaches for different dispersion map configurations, using simple single channel transmission, which results in the proposal of several design rules for the optimized deployment of ultra-long haul optical transport systems. In particular, it is concluded that dispersion unmanaged transmission is preferable in the sense of compatibility with different link design configurations as well as computational complexity requirements and maximum performance that can be achieved.

Abstract
Pico-cell based access networks are increasingly seen as a promising solution for the growing mobility and bandwidth user demands. A recently developed resonant tunneling diode oscillator integrated with a photodetector and a laser diode (RTD-PD-LD), is being considered as a viable low cost pico-cell solution for radio-over-fiber based distributed antenna systems. In this paper we experimentally evaluate both the uplink and downlink error vector magnitude performance of the RTD-PD-LD for different phase and frequency modulation formats. We conclude that frequency modulated formats achieve better performance in both uplink and downlink configurations, yet, Gaussian Minimum Shift Keying format also appears to be a practical alternative.

Abstract
In this paper we investigate the efficacy of applying the coupled field back-propagation algorithm as a post-compensation method for nonlinearity mitigation in a coherently detected fibre optic long-haul system using multi-band orthogonal frequency division multiplexed signals. Specifically, we analyze the impact of varying the band-spacing and the number of bands. We find that its efficacy is higher for largely spaced bands and a small number of bands. Additionally, we propose a method to include the Four Wave Mixing compensating term within the coupled field method to provide simplified means of multichannel compensation. We conclude that this method is more efficient in improving the performance especially for small band spacings. The coupled field method proves to be an interesting choice for the implementation of receiver-based real-time digital signal processing.