Factor graph based detection approach for high-mobility OFDM systems with large FFT modes

In this article, a novel detector design is proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency selective and time varying channels. Namely, we focus on systems with large OFDM symbol lengths where design and complexity constraints have to be taken into account and many of the existing ICI reduction techniques can not be applied. We propose a factor graph (FG) based approach for maximum a posteriori (MAP) symbol detection which exploits the frequency diversity introduced by the ICI in the OFDM symbol. The proposed algorithm provides high diversity orders allowing to outperform the free-ICI performance in high-mobility scenarios with an inherent parallel structure suitable for large OFDM block sizes. The performance of the mentioned near-optimal detection strategy is analyzed over a general bit-interleaved coded modulation (BICM) system applying low-density parity-check (LDPC) codes. The inclusion of pilot symbols is also considered in order to analyze how they assist the detection process

Antireflux procedures

In the last decade, a new philosophy to be less invasive in minimally invasive surgery and to perform laparoscopy without visible scars invested surgeons, researchers and companies. The purpose was basically the improved cosmesis, but the postoperative pain, the hospital stay, and the patient's convalescence were also attempted to be reduced. Natural orifices transluminal endoscopic surgery (NOTES) and single-port/single-incision laparoscopy (SPL/SLS) were the two principal fields of researches and investments. Due to the difficulties to perform the conventional multiport laparoscopic procedures through NOTES and sometimes also through SPL/SLS, a new philosophy to keeping in mind the desire of less invesivity of minimally invasive surgery started to be popular and named reduced port laparoscopic surgery (RPLS). In RPLS, the classic multiport laparoscopic procedures can be performed in a similar method, but through a reduced number of trocars, a reduced size of each trocar and use of needlescopic instruments. Furthermore, some intrabdominal devices can be inserted in the abdomen and used like an assistant's help or to improve the operative field's exposure. In this chapter two main antireflux procedures, Nissen fundoplication (360°) and Toupet fundoplication (270°), are described step by step using the transumbilical access, and curved reusable instruments. Each step is represented by specific drawings showing the internal triangulation, which characterizes the conventional multiport laparoscopy, and the external surgeon's ergonomy.SCOPUS: ch.binfo:eu-repo/semantics/publishe

Single-access laparoscopic approach for gastric surgery (hiatal hernia repair and gastric resections)

In the last decade, a new philosophy to be less invasive in minimally invasive surgery and to perform laparoscopy without visible scars invested surgeons, researchers, and companies. The main purpose was to improve the aesthetic, but the postoperative pain, the hospital stay, and the patient's convalescence were also attempted to be reduced. Natural orifice transluminal endoscopic surgery (NOTES) and single-access laparoscopy (SAL) were the two main fields for researches and investments. In this chapter, hiatal hernia repair with subsequent Nissen (360°) or Toupet (270°) fundoplication and gastric resections are described step by step using the transumbilical SAL. The procedures are performed with reusable trocars, conventional rigid scopes, and curved reusable instruments according to DAPRI (Karl Storz-Endoskope, Tuttlingen, Germany), which allow to maintain the cost of SAL like conventional multitrocar laparoscopy. Finally, the indications, contraindications, tips, and tricks of these SAL techniques are here reported.SCOPUS: ch.binfo:eu-repo/semantics/publishe