Ruediger Kays

Towards a convergent digital home network infrastructure

Many communication standards are available to set up consumer home networks. An intelligent combination of wired and wireless communication technologies allows exploiting many technology specific advantages while compensating disadvantages. Such a convergent digital home network infrastructure increases robustness, coverage range and availability of applications and services. In this paper, we discuss the general concept of such home networks. We present the Inter-MAC convergence sublayer as a very first approach to this concept. With the help of a typical scenario we demonstrate its feasibility. The recently initiated standardization activity IEEE P1905.1 is introduced. A global standard for convergent digital home networks can be the basis for a user-friendly network of consumer electronic devices in the home.

Improvement of IEEE 802.15.4a IR-UWB for time-critical industrial wireless sensor networks

Wireless sensor networks for industrial factory automation require high reliability and low latency. Since state of the art wireless sensor networks do not entirely meet these requirements, novel system approaches need to be developed. In this regard, ultra wideband communication systems seem to be a promising approach due to their high bandwidth and robustness against frequency selectivity. This paper analyzes the feasibility of the IEEE 802.15.4a impulse-radio ultra-wideband physical layer in the application domain of factory automation. The IEEE 802.15.4e media access control layer which is specified to meet the requirements of industrial applications is included in the analysis. Based on a realistic network and application scenario, the resulting system latency is examined. Parameter adaptions and system enhancements for latency reduction considering both physical and media access control layers are given. As a result, the performance investigation serves as a guide for selecting a suitable wireless system for the establishment of a wireless sensor network. A lower bound of resulting latency is presented.

HOMEPLANE: An architecture for a wireless home area network with management support for high quality of service

This paper describes properties of a network management concept designed in the scope of the project ldquoHOMEPLANErdquo. Following to the projectpsilas vision, the future home network has a strong focus on multimedia applications. For the userspsila convenience, media transfers are realized based on IEEE 802.11 WLAN. To ensure high quality of service different enhancement concepts have been developed and evaluated in hardware. This paper gives an overview on the fundamental concepts of wireless resource managing as well as current implementation results.

Coded Performance of OFDM and SC PHY of IEEE 802.15.3c for Different FEC Types

In order to realize wireless gigabit transmission in one room, different 60 GHz systems are emerging. For the physical layer (PHY) orthogonal frequency division multiplexing (OFDM) as well as single carrier (SC) transmission are deployed. In this paper, the fundamental studies of coded performance of both approaches are extended by comparing different forward error correction (FEC) schemes for the final version of IEEE 802.15.3c in terms of bit error rate (BER) versus Eb/N0. Our results show that the SC PHY outperforms the OFDM PHY not only for high code rates but also for low code rates when using moderate low density parity check (LDPC) codes. Thus, very efficient, low cost 60 GHz devices can be designed. Keywords-60 GHz system, OFDM, single carrier, wireless gigabit transmission

Efficiency of frame aggregation in wireless multimedia networks based on IEEE 802.11n

This paper evaluates the major MAC enhancement of IEEE 802.11n to realize high throughput, i.e. frame aggregation. In contrast to existing studies of this enhancement, we analyze the efficiency instead of the mere performance. The results show significant efficiency improvement by frame aggregation. Furthermore, the efficiency analysis leads to important conclusions for system configuration and adaptation and reveals effects which are beyond the scope of existing work. It is shown that the most feasible configuration is to apply maximum aggregation and to adapt the modulation and coding scheme (MCS) instead of the frame size. Furthermore, the efficiency analysis points out that in case the network is not saturated the 20 MHz mode is more efficient than the 40 MHz option.

Visible light communication using TV displays and video cameras

Visible light communication (VLC) is an attractive alternative to radio frequency communication for applications requiring a wireless short range link. A lot of research work has been done on this topic. Different concepts for VLC are specified in standard IEEE 802.15.7. An interesting feature is the application of existing infrastructures like LED lighting to carry data transmission on top. In this paper, we describe a new approach which applies a video display as transmitter and a digital camera as receiver. Due to a multi-parallel transmission based on individual modulation of all pixels of the screen, high data rates can be achieved. A special feature is the option to design the modulation such that data transfer runs on top of a video presentation without annoying the viewer.

Evaluation of wireless smart metering technologies in realistic indoor channels

The European energy system is currently evolving into a smart grid, and the transmission of metering values between smart meters is gaining increasing importance. Since wireless technologies have a high flexibility and can be easily integrated into existing installations, it is feasible to use them for transmission of metering values. This paper presents an evaluation of wireless smart metering standards operating in the 868 MHz frequency band according to European regulation. The standards are compared by evaluating the indoor coverage range and the energy consumption.

High efficiency broadband transmission with LDPC codes over GF(2s)

In this paper, we discuss the suitability and the improvement potential of LDPC codes over a finite extension field GF(2s) for future high efficiency broadband transmission systems through comparison with state-of-the-art coding schemes, i.e. LDPC codes according to IEEE 802.11n and DVB-X2. We first point out the differences between non-binary LDPC codes and their binary counterparts and discuss their advantages for high efficiency broadband transmission systems. For this, two mapping strategies can be introduced which allow for directly combining higher-order modulation and non-binary LDPC codes. We present simulation results in terms of bit error rates and packet error rates for various higher-order (square) quadrature amplitude modulations and LDPC codes over different finite extension fields for the AWGN channel and the Rayleigh fading channel. The evaluation reveals that the application of non-binary LDPC codes allows for the design of efficient transmission schemes with high spectral efficiencies. However, this is achieved at the expense of increased complexity.

Joint efficiency and performance enhancement of multiband OFDM ultra-wideband (WiMedia) systems by application of LDPC codes

This paper describes modifications of the WiMedia PHY which significantly increase its performance. By application of Shannon-limit approaching LDPC codes we yield a performance gain of about 4 dB at the reference bit error rate of 10-5. The simulation results are based on a realistic channel model for indoor UWB WPAN environments. Furthermore, our proposal leads to a convenient and expedient PHY and increases the system efficiency.

Reliable Broadcast Transmission in Vehicular Networks Based on Fountain Codes

Car-to-car and car-to-infrastructure communications are currently under intense research as they enable a wide variety of applications. Besides security-driven applications which require only small amounts of individual data there are also applications which require medium to high amounts of uniform data delivered to an unknown number of nodes. For this kind of broadcast and multicast applications, the use of fountain codes is highly suitable. In this paper, we investigate the applicability of fountain codes in an infrastructure-based automotive communication system and introduce an expedient method to design a system deploying IEEE 802.11p and fountain codes. By means of simulation results obtained for three representative vehicular scenarios we compare the performance of our method to an alternative method also applied in this field, i.e. the data carousel. For specific configurations the system based on fountain codes outperforms the conservative approach by a factor of four in terms of the overall throughput and thus provides the potential to significantly increase the overall efficiency.