Rüdiger Kays

Wireless ad-hoc networks with high node density for home AV transmission

Wireless ad-hoc networks are a key technology for the set up of home AV distribution system and the services supported to the consumer. Broad market penetration of such networks leads to high densities of active transmission links. The paper describes related problems and a solution approach based on the physical layer of the IEEE 802.11 standard. The concept of cooperative nodes introduced in the paper might be helpful to set up self organizing networks with high spectral efficiency for consumer homes.

Enhancement of wireless LAN for multimedia home networking

This paper describes the problems of wireless LAN usage in the users home with focus on high quality, real-time media transmission. Results of physical channel measurements with respect to fading effects and channel power are analyzed and experimentally obtained link data rates are presented. Methods for a transmitter based link adaptation are described and evaluated to increase the reliability of the physical data transmission.

ParSec: A PSSS approach to industrial radio with very low and very flexible cycle timing

Industry 4.0 is a subject of current relevance which targets detailed information acquisition from industrial production processes. Wireless communication to ease this acquisition process is highly interesting but suffers today from problems of low reliability, high latency and small flexibility. ParSec addresses these subjects by investigating an innovative, CDMA based approach with very low latency of <; 50 μs, flexible resource block scheduling and BER of ≤ 10-9. While the latency figure is completely based on the assumption that a minimum of 3 symbol durations are needed the BER comes from the requirement specification. Two forms of FEC are used to achieve this requested figure. The radio will be used in the frequency range from 5,725 to 5,875 GHz and work without listen before talk. A rapid prototype has been built to conduct channel measurements and prove the promised properties of the PSSS255 approach. The project is conducted in the framework of other “Industrial Radio” oriented projects supported by the German federal ministry of education and research (BMBF).

Prioritized medium access in ad-hoc networks with a SystemClick model of the IEEE 802.11n MAC

For ad-hoc home networks without central coordinator, IEEE 802.11 systems merely support service differentiation. In many usage scenarios of a typical home network with applications requiring a strict quality of service (QoS), this MAC functionality is not sufficient. In order to counteract this problem, we developed in previous works a modified MAC scheme based on the IEEE 802.11 enhanced distributed channel access (EDCA) function. This paper describes enhancements of the modified MAC scheme enforcing prioritized medium access for strict QoS applications. For the first time, the established concept is realized in a distributed way with in-band signaling. Our enhanced MAC is embedded into a comprehensive IEEE 802.11n reference application to demonstrate its effectiveness in combination with the latest amendments like frame aggregation. The reference application is modeled in SystemClick, a framework for describing and evaluating packet processing applications on resource constraint network nodes. This enables functional validation and provides a path to future, cost-efficient implementations on programmable devices. On this basis, the paper presents simulation results substantiating the significant improvement of QoS parameters like delay and throughput. Besides enforcing strict priorities, collisions can be reduced to zero and the average waiting time can be decreased by up to 33 % for typical usage scenarios.

Technical and economic analysis of future smart grid applications in the E-DeMa project

The increasing power feed-in from renewable energy sources entails an impact on the operation of transmission and distribution grids as well as the energy market and its players. It offers new opportunities for existing market players to expand their business and supports the market launch for new market players with new products. In this paper, different electricity products which are tested within the field testing deployment of the German research project “Development and Demonstration of Locally Networked Energy Systems to the E-Energy Marketplace of the Future” (E-DeMa) will be described. To provide these demand-oriented tariffs, an appropriate well dimensioned information and communication infrastructure and its components are required and therefore described in detail. Three scenarios and four topologies are defined for the analysis of the technical and economic potential for market players regarding these products. At the end, the results for the market players customer, retailer and aggregator are presented.

Parallel Sequence Spread Spectrum: Analytical and simulative approach for determination of bit error probability

Communication in industrial applications like factory automation (FA) demands very low latency combined with high reliability. Since state of the art wireless technologies are not entirely fulfilling FA requirements, novel approaches are being developed. In this context Parallel Sequence Spread Spectrum (PSSS) is a promising technology, which enables shortest latencies, whereas its bit error performance has not yet been analyzed. Similar to Direct Sequence Spread Spectrum (DSSS), where data symbols are spread each with an appropriate sequence, PSSS spreading is performed based on a cyclically shifted m-sequence. Each cyclic shift of the base m-sequence is code, which enables a CDMA scheme. This paper deduces a theoretical and simulative approach determining the bit error performance for an ideal CDMA and for a time offset between several nodes in an AWGN channel. Based on this analysis, performance constraints and reliability limits such as requested synchronization accuracy are revealed.

Coverage Range Analysis of Wireless Technologies for Industrial Automation

Reliable wireless communication is crucial to current and future industrial applications, but is however not yet applicable in many scenarios. Thus novel approaches are being investigated at the moment, from which three physical (PHY) layer technologies are depicted for detailed evaluation in this paper. Preceding the performance analysis, industrial application requirements and constraints as spatial extent, number of nodes, cycle time, PER and user data length are summarized. Error rates and coverage ranges are calculated and presented for Ultra Wide Band (UWB), Frequency Hopping Spread Spectrum (FHSS) and Parallel Sequence Spread Spectrum (PSSS) assuming an AWGN channel.

Dynamic Characteristics of Wireless Lan Channels for Multimedia Home Networks

This paper describes dynamic frequency selection (DFS) as a method to improve wireless local area network (wireless LAN or WLAN) capacity in home environments with focus on reliable media transmission. The gain obtained with this method is evaluated based on measurements of the dynamic behaviour of wireless channels. The application of DFS for each link between two nodes in ad-hoc mode can improve the performance of home media networks.

Practical limitations of Ethernet-based inhouse multimedia distribution

100 Mbit/s Ethernet seems to be suited for an integrated digital home network combining PC interconnection and audiovisual entertainment devices. The MAC procedure 100 Mbit/s Ethernet lacks QoS (quality of service) in collision domains. This paper presents a proposal of an easy to implement, reliable and compatible MAC based QoS mechanism that fills this gap. Measurements with respect to the QoS parameters show the performance of our proposal. These measurements also exhibit, that 100 Mbit/s Ethernet easily meets QoS specifications for audio and video if proper network equipment is selected.

Performance and interoperability evaluation of radiofrequency home automation protocols and Bluetooth Low Energy for smart grid and smart home applications

The paper presents an evaluation of the performances and the coexistence of standard home automation radiofrequency protocols such as KNX-RF Multi, Zigbee and EnOcean with Bluetooth Low Energy protocol available in smartphone and tablets in the domain of smart grid and smart home. This work allows describing an overall interoperable and efficient radiofrequency system in this domain based on the strengths of each available RF standard.