Quality of Service Support for Real-Time Multimedia Applications over Wireless Links Using the Simultaneous MAC-Packet Transmission (SMPT) in a CDMA Environment

The goal of this paper is an introduction to a mechanism called "Simultaneous MAC Packet Transmission (SMPT)" that attempts to stabilise the Quality Of Service (QoS) of a wireless CDMA system in terms of throughput, loss rate and delay even if the propagation conditions on the wireless media changes dramatically. We apply this mechanism to multimedia applications which suffer from the instability of wireless links. The suitability of our approach is shown by observing its effects on typical QoS parameters of multimedia applications by simulations. I. Introduction In the future there will be an increasing demand for multimedia services. Multimedia applications typically need stable throughput, small jitter and a limited loss rate. Until recently, multimedia protocols were designed for fixed networks. But the ongoing development of omnipresent mobile communication environment makes solutions necessary that are suitable for mobile and wireless networks. In contrast to fixed networks wir..

Supersim - A New Technique For Simulation Of Programmable DSP Architectures

This paper presents a technique for simulating DSP processors based on the principle of compiled simulation. Unlike existing, commercially available instruction set simulators for DSP processors, which are of interpretive character, the proposed technique performs instruction decoding and simulation scheduling at compile time. The technique offers up to three orders of magnitude faster simulation. The high speed allows the user to explore algorithms and hardware /software trade-offs before any hardware implementation. Moreover, the user can tailor the compiled simulation to trade speed for more accuracy. In this paper, the sources of the immense speedup are analyzed and the realization of the simulation compiler is presented. I. Introduction Designers of today's DSP systems --- such as digital cellular phones and multimedia systems --- face rising complexity and quickly changing system requirements. To deal with these challenges, designers have increasingly turned to programmable arc..

Simultaneous MAC-Packet Transmission in Integrated Broadband Mobile System for TCP

In this paper we show how the simultaneous MAC packet transmission over a wireless system using the CDMA technology can be improved. The main idea behind our approach is, that in opposite to common wireless CDMA systems, where each mobile station has one code for all connections, we supply the mobile with multiple codes for a single connection. This opens the possibility to transmit multiple packets in parallel, each packet with a different code. The motivation for using multiple codes for each connection is to stabilise the quality of service (QoS). We give a first impression how our approach improves TCP throughput with simultaneous MAC packet transmission. 1 Introduction On the assumption that we have the possibility within a mobile communication system to allocate more than one CDMA channel for one communication session, we want to show the improvements that can be achieved. Wireless channels are typically characterised by a high bit error rate. To guarantee a nearly error free co..

Insights into the stereospecificity of ketoreduction in a modular polyketide synthase

Ketoreductase enzymes are responsible for the generation of hydroxyl stereocentres during the biosynthesis of complex polyketide natural products. Previous studies of isolated polyketide ketoreductases have shown that the stereospecificity of ketoreduction can be switched by mutagenesis of selected active site amino acids. We show here that in the context of the intact polyketide synthase multienzyme the same changes do not alter the stereochemical outcome in the same way. These findings point towards additional factors that govern ketoreductase stereospecificity on intact multienzymes in vivo

Do selective radiation dose escalation and tumour hypoxia status impact the loco-regional tumour control after radio-chemotherapy of head & neck tumours? The ESCALOX protocol.

Background: Standard of care primary treatment of carcinoma of locally advanced squamous cell head and neck cancer (LAHNSCC) consists of platinum-based concomitant chemo-irradiation. Despite progress in the treatment of LAHNSCC using modern radiotherapy techniques the outcome remains still poor. Using IMRT with SIB the escalation of total dose to the GTV is possible with the aim to improve clinical outcome. This study tests the hypothesis if radiation dose escalation to the GTV improves 2-year-LRC and -OS after concomitant chemo-irradiation. Methods: The ESCALOX trial is a prospective randomized phase III study using cisplatin chemo-irradiation and the SIB-IMRT concept in patients with LAHNSCC of the oral cavity, oropharynx or hypopharynx to escalate the total dose to the GTV up to 80.5 Gy. Chemotherapy is planned either in the 1st and 5th week (cisplatin 20 mg/m2/d d 1-5 and d 29-33) or weekly (cisplatin 40 mg/m2/d) during RT. RT is delivered as SIB with total doses of 80.5 Gy/70.0 Gy/56.0 Gy with 2.3 Gy/2.0 Gy and 1.6 Gy in the experimental arm and in the control arm with 70.0 Gy/56.0 Gy with 2.0 Gy and 1.6 Gy. A pre-study with dose escalation up to 77.0 Gy/70.0 Gy/56.0 Gy with 2.2 Gy/2.0 Gy and 1.6 Gy is demanded by the German federal office of radiation protection (BfS). In the translational part of the trial 100 of the randomised patients will be investigated by 18-F-FMiso-PET-CT for the presence and behaviour of tumor hypoxia twice in the week before treatment start. Discussion: The primary endpoint of the pre-study is acute radiation induced toxicity. Primary endpoint of the main trial is 2-year-LRC. By using the dose escalation up to 80.5 Gy to the GTV of the primary tumor and lymph nodes > 2 cm a LRC benefit of 15% at 2 years should be expected. The ESCALOX trial is supported by Deutsche Forschungsgemeinschaft (DFG); Grant No.: MO-363/4-1. Trial registration: ClinicalTrials.gov Identifier: NCT 01212354 , EudraCT-No.: 2010-021139-1