Figure 2 shows our experimental results with original outdoor MICA2 data in paper [9]. We select the top N ��nearest�� sequences instead of one sequence when searching the location sequence table. In this case, when N = 2, the minimal average localization error can be obtained.Figure 2.Localization errors due to N.In addition, we also notice that the localization errors for nodes near the border of the region are possibly rather large. For example, in Figure 3, when mobile node M falls into region F1, its coordinate will be estimated as the centroid of F1 if no measurement errors exist. In fact, the real position of M is closer to the centroid of region E1, even F2.Figure 3.Localization for marginal nodes.To reduce the average localization errors and improve the localization accuracy for marginal nodes, a new sequence-based localization method: N-best SBL, is presented.

The best N is first estimated by using random sampling based on a wireless channel fading model, and then the coordinate of the mobile target is obtained with weighted computing of top N sequences.3.?Anchor-Free Localization Method in C-WSN3.1. Coal mine wireless sensor networksTo execute our localization algorithm, first a C-WSN was constructed in underground mines based on the ZigBee technology. We deployed the sensor nodes, called Cicada, as end d
The use of wavelength measurement has a wide range of applications, varying from fiber-optic communication to biological purposes, such as DNA sequencing, including many engineering applications.

This increase of applications has provided motivation to improve all elements of the optical sensing chain, as well as the photodetector fabrication process, conditioning circuits and readout algorithms. In this sense, the most state-of-the-art BICMOS (combination of bipolar and CMOS technology) optical sensors involve a trade-off between implementation cost and readout accuracy.In general, the well known methods for either color identification or wavelength measurement use color filters. In principle three photodetectors are covered respectively by red, green and blue filters which increases both silicon surface and implementation cost due to the deposition of optical filters (nonstandard BICMOS processing) [1�C3]. In this perspective, the buried triple pn junctions (BTJ) structure, using BICMOS process (Figure 1), provides a promising alternative.

Unlike the GSK-3 conventional photodetectors the BTJ has three outputs according to captured light; hence three different spectral responses (Figure 2) carry the wavelength value. Different process parameters, such as doping profiles allow conceiving three bandpass filters curves adjusted, with a limited resolution, in blue, green and red areas [1]. Due to process parameters variations from one chip to another, the bandpass filters shape change significantly, and as a result, this lowers the readout accuracy.