Wolfgang Endemann

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.

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.

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.

High efficiency wireless LAN for multimedia home networks

This work describes the problems of wireless LAN usage in the users home with focus on media transmission. Results of channel measurements with respect to fading effects are presented. The resulting link data rates are analyzed. Methods for a transmitter based link adaptation are evaluated to increase the reliability of the physical data transmission.

Modeling of the dynamics of wireless in-house channels

This paper describes two dynamic channel models, which have been developed based on WLAN channel measurements in the 2.4 GHz band. These models can be used to simulate dynamic channel characteristics in home environment and serve to design link adaptation methods in adaptive wireless networks.

Augmenting OFDM wireless local networks with motion detection capability

Ubiquitous wireless local networks which use channel transfer function estimation to compensate for echoes on the wireless channel are uniquely suited for motion detection as a secondary use. In this way, added value can be provided without additional hardware. This paper presents a procedure with uses channel state information of an IEEE 802.11 High Throughput wireless link to reliably detect the presence of moving items, such as people crossing a room. By leveraging CSI instead of RSSI, the frequency-selective fading characteristic of indoor wireless channels can be taken into account while eliminating the effect of power level fluctuations in consumer-grade wireless hardware.

Scalable and efficient car communication topology

Car communication acts as a base for advanced traffic and car services. There is a strong potential to utilize existing hardware to introduce first car communication applications and services. Potentially first car communication technologies should be seen as initial base to learn about car communication while not all expected functions can be realized with this setup. The more time critical the required communication for a specific car communication application is, the more optimized communication technologies are needed. Considering only already existing communication technologies like UMTS and WLAN, there is a significant potential to implement first car communication solutions in near future. Thus this paper investigates which network topologies provide enough scalability and efficiency to realize first car communication functions based on available hardware.