1,721,032 research outputs found
On the Selection of Adaptive Modulation and Coding Modes over OFDM
No full textIn this paper we address the problem of how best
selecting the smallest set of transmission modes (i.e. modulation
and channel code formats) to be employed in adaptive modulation
and coding (AMC) schemes for OFDM. In fact, by decreasing the
number of allowable modes, the complexity of the ACM scheme is
greatly reduced. The method makes use of an optimum throughput
maximization algorithm for the bit and power allocation. We
start with a large set of possible transmission modes. Then, for
a given channel, we iterate the loading algorithm with mode sets
having successive removal of the mode which yields the smallest
contribution to the overall throughput. By using this method in a
Rayleigh fading channel, we are able to show that in the test case
of the HIPERLAN/2 modes, up to five modes out of seven can
be removed with a very small impact on the average achievable
throughput
[Current aspects and controversies in reconstructive surgery after esophagectomy: personal experience].
No full textThe authors report their series of 184 esophagectomies performed both for benign (44) and malignant (140) diseases. On the basis of their experience and supported by Literature data, it is believed restoration of digestive continuity offers two main points of discussion: choice of the intestinal tract for the interposition and type of anastomosis to perform. The nature of the lesion and its level seems to play the most important role in the choice
Method of bit and power loading in OFDM communication systems with modulation and coding adaptation
No full text[Special problems in the surgical treatment of megaesophageal cardial achalasia. A clinical case].
No full textThe paper report the case of a patient brought to the Authors' attention suffering from megaesophageal cardial achalasia who had already undergone gastroduodenal resection according to BII. It was considered worthwhile to report this case due to the problems which arose concerning the choice of a thoracic rather than abdominal route owing to the impossibility of associating cardiomyotomy with anti-reflux plastica surgery because of the reduced dimensions of the stomach
[Dysphagia associated with aorto-cardiac compression on the distal esophagus: a rare event but not exceptional in the elderly].
No full textAmong the pathologies responsible for dysphagia in the elderly, the aortic compression on the distal oesophagus awakens a certain clinical interest. Cipho-lordosis, which is often present in aged females, worsens the effects of this compression causing other kinkings on the oesophagus already hypokinetic because of the age (presbyoesophagus). This illness often shows scare symptoms, but sometimes requires a pneumatic dilation to allow normal food assumption of the patient. The authors report on their experience of two cases, clearly documented from the diagnostic point of view; the first one was given medical treatment, the second one was treated with a pneumatic dilatation of the cardias
Risultati della terapia chirurgica per via laparoscopica della MRGE. Esperienza di scuola
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