Single Antenna Techniques

One of the challenges in designing a wideband MIMO system is tremendous processing requirements at the receiver. MIMO symbol detection involves detecting symbol from a complex signal at the receiver. This detection process is considerably complex as compared to single antenna system. Several MIMO detection techniques have been proposed [8], These detection techniques can be broadly divided into linear and non-linear detection methods. Linear methods offer low complexity with degraded BER performance as compared to non-linear methods. This paper focuses on non-linear detectors and makes an effort to improve BER performance at the cost of complexity and vice versa. ML and V-BLAST detectors [9],[10] are well known non-linear MIMO detection methods. ML outperforms VBLAST in BER performance, while VBLAST is lesser complex than ML. In [11],[12] a performance complexity trade off between the two methods have been reported. 

The identification of xanthophylls in vivo is a complex task and should be approached gradually with the increasing complexity of the sample. In the case of the antenna xanthophylls, the simplest sample is the isolated LHCII complex. Even here four xanthophylls are present, each having at least three major absorption transitions, 0-0, 0-1, and 0-2 (Figure 7.4). Heterogeneity in the xanthophyll environment and overlap with the chlorophyll absorption add additional complexity to the identification task. No single spectroscopic method seems suitable to resolve the overlapping spectra. However, the combination of two spectroscopic techniques, low-temperature absorption and resonance Raman spectroscopy, has proved to be fruitful (Ruban et al., 2001 Robert et al., 2004). 

Fig. 4. Detection of single molecules by near-field techniques, (a), (b) SNOM images of single molecules embedded in a polymer film with random orientations, from [29]. (c) Sketch of the field distribution in the near field of the aperture, (d) Comparison of measured field distributions to calculated, once for both fundamental orientations, from [27]. (e) Effect of an optical antenna on the emission of a single emitter [36].

Recently electrophysiological experiments by Sasz have yielded results which would indicate that not only periplanone-B, but also periplanone-A could be a genuine pheromone. With single cell recording techniques he demonstrated the presence of many olfactory hairs on the antennae of Periplaneta americana that were very sensitive to periplanone-A, whereas others were sensitive for periplanone-B (41). 

Briefly, diversity allows to increase the RX signal level without any additional increase of TX power or, equivalently, to obtain the same received power as in the single RX antenna case but at remarkably lower TX power. We describe an example of state-of-the-art implementations of wearable antenna diversity techniques in the following section. 

Several AM techniques have been modified to work at a small scale to deposit passive electronic structures (conductors, insulators, resistors, antennas, etc.). These techniques are often known as direct-write techniques and, for instance, use electronic inks that contain nanoparticles or other additives that result in electronic properties after drying, thermal decomposition, or other post-treatment. By combining direct-write techniques with other AM techniques it becomes possible to create multifunctional 3D-embedded electronic structures on a layer-by-laycT basis that combine structural, thermal, electronic, and other functions into a single component. 

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