Frank Reichert

MINT-a mobile Internet router

The mobility of portable computers and workstations is not transparent to users. They adjust to reduced services as long as they have no connection to a supporting infrastructure. The goal of the Walkstation project is to realize a user transparent mobile IP router (MINT) for wireless links (infrared and radio) operating at 1-10 Mbit/sec. For the study of user behavior and system characteristics, a campuswide testbed (ERIC) with 50-100 stations is planned to demonstrate the new solutions found in the Walkstation II project.Today, mobility of portable computers and workstations is not transparent to users. They adjust to reduced services as long as they have no connection to a supporting infrastructure. The goal of the Walkstation project is to realize a user transparent mobile IP router (MINT) for wireless links (infrared and radio) operating at 1-10 Mbit/sec. For the study of user behavior and system characteristics a campus wide testbed (ERIC) with 50-100 stations is planned to demonstrate the new solutions found in the Walkstation II project.<<ETX>>

A multiport mobile internet-router

In the Swedish Walkstation project a device for mobile hosts and base stations is realized by the same kind of hardware but with different kinds of communication software. This device, called MINT (Mobile IP Router), consists mainly of three parts, one for the connection to the host or backbone net (Ethernet), one for connecting to wireless LANs (radio or infrared), and a processing part for computing the communication protocols. This device serves as more than a mobile modem, i.e., it actually routes packets over potentially multiple paths with varying connectivity and quality. By using Ethernet as an input channel, it should not be necessary to install special purpose wiring dedicated to mobile communication. Instead the existing network, which normally is globally available, is used to select suitable sites for base stations. To realize a large scale field trial the new router must be low cost, small in size, and have a low power consumption while offering high performance. The current phase of the project involves building a 68030 based router with multiple interfaces, including as host interfaces: SCSI, Ethernet, serial, parallel; and as wireless interfaces: IR, microwave-radio, or a-second Ethernet (supported for software development).<<ETX>>

Direct sequence CDMA technology and its application to future portable multimedia communication systems

The design of flexible and efficient future mobile communication systems is a major challenge. The Walkstation Project involves researchers from different areas in order to find a solution via a global system approach. An important task is the investigation of new digital, highly integrated radio interfaces with low cost, small size and low power consumption based on direct sequence CDMA. The simplicity of the design of both the analog and digital parts will allow low power operation and small area in an eventual BiCMOS implementation.<<ETX>>

The PRMA-ISA protocol for multiple access of mixed voice and data traffic

A combined multiple access protocol is investigated, based on the ISA algorithm, which was first introduced for a slotted unframed channel, and later modified to fit a cellular wireless network with distributed handoff. ISA manages the access rights at the beginning of each slot in order to maximize the success probability (one step throughput), based on an independence assumption on the presence of packets at the stations. We extend this concept in the context of a framed channel that has the same basic structure as packet reservation multiple access (PRMA). In this case, it is possible to see the frame as a whole bunch of parallel channels, over which the overall success probability must be maximized at the beginning of the frame for all free slots. The combined PRMA-ISA algorithm has been developed and investigated by means of simulations, using models previously proposed for data and voice (phone calls) traffic.<<ETX>>

Network management in short-range mobile radio networks: Performance tuning optimizes collision behaviour

The authors evaluate several network management algorithms to increase the performance of short-range mobile radio networks concerning collision avoidance and reduction of collision duration measured in frames. It is shown that suitable choice of transmission power with independent antenna systems fulfils requirements of applications while increasing the communication performance. The evaluations are made by simulations of a three-lane unidirectional highway. It is shown that earlier investigations of optimal transmission ranges are not satisfactory compared to the requirements of applications.<<ETX>>

The Walkstation transceiver design

The design of flexible and efficient future mobile communication systems is a major challenge. The Walkstation Project involves researchers from different areas in order to find a solution via a global system approach. An important task is the investigation of new digital, highly integrated radio interfaces with low cost, small size and low power consumption based on direct sequence CDMA. The simplicity of the design of both the analog and digital parts will allow low power operation and small area in a eventual BiCMOS implementation.<<ETX>>

Implementation of communication and management protocols for the integrated road transport and traffic environment

We propose a protocol architecture for the European Integrated Road Transport and Traffic Environment (IRTE)/Intelligent Vehicle Highway System (IVHS). As a basis to maximize integration at application and subnetwork levels, we seek inspiration from the ISO8473 Connectionless Network Protocol recommendation, as well as from some other ISO/OSI standards. We claim our approach strikes an adequate balance between conventional protocol composition, and IRTE industrial concerns. By implementing the favored protocol architecture in a testbed, we also give evidence that such a balanced approach is not a vision of a distant future.<<ETX>>