Application of Space-Time Diversity/Coding For Power Line Channels

The purpose of the present work is to evaluate the application of space-time block codes to the transmission of digital data over the power-line communication channel (PLC). Data transmitted over the power-line channel is usually corrupted by impulsive noise. In this work we analyse the performance of space-time block codes in this type of environment and show that a significant performance gain can be achieved at almost no processing expense

Two-Dimensional Interleaving Schemes with Repetitions

We present 2-dimensional interleaving schemes, with repetition, for correcting 2- dimensional bursts (or clusters) of errors, where a cluster of errors is characterized by its area. A recent application of correction of 2-dimensional clusters appeared in the context of holographic storage. Known interleaving schemes are based on arrays of integers with the property that every connected component of area t consists of distinct integers. Namely, they are based on the use of 1-error-correcting codes. We extend this concept by allowing repetitions within the arrays, hence, providing a trade-off between the error-correcting capability of the codes and the degree of the interleaving schemes

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Space-time block codes with rate >= 1 for power line channels

In this paper, the utilisation of space-time block codes (STBC) for high-speed communications over power line channels (PLC) affected by quasi-static flat Rayleigh fading and additive man-made asynchronous impulsive noise is presented. Although the diversity order is severely reduced in a 3-phase PLC environment with respect to wireless MIMO channels, our simulation results for a rate-1 real orthogonal STBC scheme demonstrate significant gains over an uncoded system operating with the same diversity advantage. In addition, taking advantage of the spatial orthogonality provided by the power line channel, a rate-3/2 real non-orthogonal space-time block code with reduced diversity order is constructed. It is shown that using the proposed high-rate code in a power line communication system yields good performance with very high spectral efficiency

Decomposable codes based on two-dimensional array codes

In this paper, we present a construction method for obtaining the decomposable codes that are originated from two-dimensional array codes and of the form |a1+x|···|am+x|a1 +···+am+x+y|. Many best known codes can be constructed using this method