Ericsson (Netherlands)

Presents information and current topics of interest to the global communications industry.

This book provides a comprehensive overview of the state-of-the-art, data flow-based techniques for the analysis, modeling and mapping technologies of concurrent applications on multi-processors. The

Today's smartphones and tablets contain multiple cellular modems to support 2G/3G/4G standards, including Long Term Evolution (LTE). They run on complex multi-processor hardware platforms and have to meet hard real-time constraints. Dataflow modeling can be used to design an LTE receiver. Static dataflow allows a rich set of analysis techniques, but is too restrictive to model the dynamic behavior in many realistic applications, including LTE receivers. Dynamic dataflow allows modeling of many realistic applications, but does not support rigorous temporal analysis. Mode-Controlled Dataflow (MCDF) is a restricted form of dynamic dataflow, and allows the same analysis techniques as static dataflow, in principle. We prove that MCDF is sufficiently expressive to handle the dynamic behavior of a realistic LTE receiver, by systematically and stepwise developing a complete MCDF model for an LTE receiver.

We present and analyze the requirements of our problem and design a Software Framework (SF) that addresses all of them. We start the chapter by defining terminology and describing our hardware architecture model. We then inventorize the requirements that the SF must address. This is followed by a discussion of the chosen Model of Computation and the overall resource management strategy, including the choice of local schedulers and task synchronization techniques. From this, we identify the main software components of the solution and present an overview of the complete SF, including the compilation chain and the runtime support. We then give a quick overview of components such as the programming language and code generator, which will not be discussed in further detail in this book. We compare our proposal with related work and close the chapter by stating our conclusions.KeywordsSoftware FrameworkResource Management StrategyTime Division MultiplexHigh Priority TaskRemote Procedure CallThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Ad-hoc systems can be characterized by the absence of infrastructure and centralized control. While the foregoing properties facilitate easy deployment, radio propagation conditions in ad-hoc networks are much more unpredictable than in planned and systematically laid-out cellular networks. Because of this difficulty to anticipate the channel conditions, approaches that have successfully been used to optimize the overall radio network performance of cellular systems cannot simply be applied to ad-hoc systems. Instead, these optimization approaches have to be evaluated carefully for their applicability in ad-hoc environments. This paper explains what should (additionally) be taken into account when designing forward error correction, power control, link adaptation, or carrier sensing schemes for ad-hoc networks. Motivated by the scientific and industry attention that Bluetooth is receiving, it is used here as an example technology. This paper shows that for Bluetooth neither link adaptation nor carrier sensing are appropriate means to improve the radio network performance, that an automatic repeat request algorithm need not be supported by forward error correction and that signal strength based power control performs best in case of full compensation of the path loss variation.

With the increasing use of multimedia technologies, image compression requires higher performance as well as new functionality. To address this need in the specific area of still image encoding, a new standard is currently being designed: JPEG2000. We see what the exact goals are of this future standard, which applications it addresses and the current standardisation process. Then we show through the descriptions of two available demonstrations what kind of results are already reachable with the current status of the standard. The first demonstration describes a Java implementation of the future standard, details the advantages of such an implementation and compares the performance of JPEG2000 with that of JPEG. The second demonstration describes how JPEG2000 can be used in domains were the transmission bandwidth is very restricted, taking advantages of new functions such as the definition of regions of interest and progressive transmission.

During 1991 field trials were performed with an indoor wireless system, specially designed for office applications. The system, based on CT3 technology uses multi carrier/time division multiple access/time division duplex (MC/TDMA/TDD) and operates in the 900 MHz band. It includes capabilities such as dynamic channel selection (DCS) and (mobile determined) handoff. The author reports on some of the technical results of the trials as well as on observations, made during the trials on the impact these systems have on the behaviour of the users. It is concluded that handoff is a necessary feature for a wireless office system in order to serve the requirements of a business environment. >