Decomposition of optical MIMO systems using polynomial matrix factorization

Within the last years the multiple-input multiple-output (MIMO) technology has revolutionized the optical fiber community. Theoretically, the concept of MIMO is well understood and shows some similarities to wireless MIMO systems. The interference in broadband MIMO systems can be removed by applying a spatio-temporal vector coding (STVC) channel description and using singular value decomposition (SVD) in combination with signal pre- and post-processing. In this contribution a newly developed SVD algorithm for polynomial matrices (PMSVD) is analyzed and compared to the commonly used SVD-based STVC. The PMSVD is implemented by an iterative polynomial matrix eigenvalue decomposition (PEVD) algorithm, namely the second order sequential best rotation algorithm (SBR2). The bit-error rate (BER) performance is evaluated and optimized by applying bit and power allocation schemes. For our simulations, the specific impulse responses of the (2 × 2) MIMO channel, including a 1.4 km multi-mode fiber and optical couplers at both ends, are measured for the operating wavelength of 1576 nm. The computer simulation results show that the PMSVD could be an alternative signal processing approach compared to conventional SVD-based MIMO approaches in frequency-selective MIMO channels

POPRAWA WŁAŚCIWOŚCI CZUJNIKÓW ŚWIATŁOWODOWYCH Z UŻYCIEM PRZETWARZANIA MIMO

Optical fiber sensors have reached a high state of maturity. Besides the high number of sensor groups, multi-mode fiber evanescent field sensors can be found in a lot of applications. Here, the signal source commonly excites many optical modes under steady-state conditions. Perturbations of the fiber then produce leaky modes. Thus, a simple intensity detector measures the degree of perturbation. In some cases also restricted mode launching conditions have been applied. They resulted in higher sensitivity but showed a narrower measurement range. Considering the individual modes as carriers of information we adapted multiple-input multiple-output (MIMO) signal processing which is well studied in the telecommunications community, for improvements on both the sensor sensitivity and its measurement range. In this paper MIMO signal processing is investigated for fiber optic sensor applications. A (2x2) MIMO implementation is realized by using lower-order and higher-order mode groups of a gradient-index multi-mode fiber as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the layer specific weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fiber optic sensor applications. The experimental results also verified the superior sensitivity and measurement range when MIMO signal processing is utilized.Czujniki światłowodowe osiągnęły wysoki stan dojrzałości technologicznej. Wśród dużej liczby typów czujników, wiele zastosowań znajdują wielomodowe czujniki zanikającego pola. Najczęściej w tych czujnikach źródło promieniowania w stanie ustalonym wzbudza wiele modów. Zaburzenia we włóknie powodują powstanie modów wyciekających. Tak więc, prosty czujnik natężenia mierzy stopień zaburzenia. W pewnych przypadkach zastosowano ograniczenia wzbudzania modów. Spowodowało to wzrost czułości lecz jednocześnie ograniczyło zakres pomiarowy. W celu poprawienia zarówno czułości, jak i zakresu pomiarowego, zastosowana została dobrze znana w telekomunikacji technika przetwarzania sygnałów MIMO (wiele wejść wiele wyjść) traktująca poszczególne mody jako nośniki informacji. W artykule opisano badania nad zastosowaniem techniki przetwarzania sygnałów MIMO do czujników światłowodowych. Implementacja MIMO (2x2) została zrealizowana poprzez podział modów w gradientowym światłowodzie wielomodowym na grupę wyższego i niższego rzędu i użyciu ich jako dwa osobne kanały transmisyjne. W czujniku mikrozgięciowym nacisk zmienia charakterystyki transmisyjne tych kanałów wprowadzając dodatkowy przesłuch. Poprzez obserwację konkretnych współczynników równań MIMO można wyznaczyć wartość nacisku. Doświadczenia potwierdziły dobrą korelację między zmianami współczynników wagowych MIMO i obciążenia czujnika, a więc potwierdziły, że przetwarzanie sygnału MIMO może być z korzyścią wykorzystywane w czujnikach światłowodowych. Wyniki doświadczalne potwierdziły również doskonałą czułość i zakres pomiarowy przy wykorzystaniu przetwarzania sygnału MIMO

Optical fibre sensors based on multi-mode fibres and MIMO signal processing: An experimental approach

In this paper multiple-input multiple-output (MIMO) signal processing is investigated for fibre optic sensor applications. A (2 × 2) MIMO implementation is realized by using lower-order and higher-order mode groups of a graded-index (GI) multi-mode fibre (MMF) as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fibre optic sensor applications. © 2015 SPIE

Angiotensin receptor blocker selectivity at the AT- and AT-receptors: conceptual and clinical effects

Summary The advent of specific angiotensin II (Ang II) receptor blockers (ARBs) some ten years ago has provided substantial information on the specific actions of the AT 1 - and AT 2 -receptors. Most of the early research concentrated on the AT1-receptor, and the actions and biological roles of the AT 2 -receptor are much less well characterised. The AT 2 -receptor is involved in the inhibition of cell proliferation, and in cell differentiation and development, regeneration and apoptosis. By raising local Ang II concentrations at the AT 2 -receptor, selective blocking of the AT 1 -receptor may therefore have beneficial effects. This concept may be important for antihypertensive therapy and in cardiovascular disease in general

Genetic alterations in human papillomavirus-associated oropharyngeal squamous cell carcinoma of patients with treatment failure

Objectives: Despite improved survival rates of patients with HPV-associated OPSCC, a subset has distant metastasis or develops local recurrence during follow-up. To investigate potential underlying genetic alterations, we analyzed patients with HPV-driven OPSCC who suffered from recurrence in comparison to matching pairs with successful tumor control. Materials and methods: We performed chromosomal copy number analyses and targeted next generation sequencing using a custom panel comprising genes that are frequently mutated in HPV-associated OPSCC. Results: Specific differences regarding chromosomal aberrations were not observed between both groups. In HPV-driven OPSCC from patients with recurrence we found higher mutation rates compared to patients with successful tumor control. Especially mutation rates of HRAS (p <= 0.05) PIK3R1, STK11 and TP63 (p <= 0.1 each) were statistically significant or trending towards significance. The respective genes can be linked to transcription factors and signaling pathways involved in cell cycle regulation, proliferation and survival. Additionally, combinations of alterations were observed on chromosomes 16 and 19, which might also influence outcome. Conclusion: Patients with HPV-driven OPSCC who develop recurrence or have metastasis may be defined by genetic alterations that might be responsible for poor outcome after standard therapy. This might be of importance for stratification in future de-escalation and targeted therapy

Mutation patterns in recurrent and/or metastatic oropharyngeal squamous cell carcinomas in relation to human papillomavirus status

Patients with HPV-driven (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) have a significantly improved overall survival compared to patients with HPV-negative (HPV-) OPSCC. Nevertheless, 13%-25% of patients with HPV+OPSCC develop local/distant recurrence (LDR) and have a course of disease similar to HPV-OPSCC. We hypothesize that HPV+OPSCCs of patients with LDR have a mutation frequency and pattern similar to HPV-OPSCCs, which is associated with severe outcome. We performed targeted next-generation sequencing using a customized gene panel and compared data from 56 matched HPV+and HPV-OPSCC of patients with/without LDR regarding protein-altering variants. Despite improved overall survival of patients with HPV+OPSCC, those who develop LDR show a strongly reduced survival rate that is similar or even worse compared to HPV-OPSCC patients. Overall, the number of mutations was similar in OPSCC of patients with and without LDR. In total and with respect to TP53, HPV-OPSCC had significantly more protein-altering mutations than HPV+OPSCC. The number of mutations was similar in HPV-OPSCC of patients with and without LDR with the exception of FAT1, which was mutated more frequently in patients without LDR. In HPV+OPSCC, HRAS, PIK3R1, STK11 and TP63 were more frequently mutated in patients with LDR compared to patients without. HPV+OPSCC of patients with LDR have a similar mutation pattern as HPV-OPSCC, except TP53, which was mutated to a significantly lower extent. In conclusion, HPV-and HPV+OPSCC with LDR have similar mutation counts in the analyzed genes. We suspect that the number of mutations is not causal for disease progression, rather specific mutations could be important