H/2 SDL in Hard Real Time System
Authors: Wijaya, Harianto and Klein, Ole
Department of Communication Networks (ComNets), Faculty 6, RWTH Aachen University
Contact: publications@comnets.rwth-aachen.de
In The Third IEEE Workshop on Wireless Local Area Networks, Boston, USA, 2001.
Publication Date: Sep, 2001
On page(s):
ISBN:
Abstract The project COVERAGE (Cellular OFDM system with Extension Points for increased transmission RAnGE), supported by the German Ministry of Education and Research (BMBF), was initiated by Siemens AG. The main objective of this project is to observe and to develop Multi-Hop networks. For this purpose, an OFDM (Orthogonal Frequency Division Multiplexing) testbed that operates at 5 GHz frequency band [1], has being developed. Another objective is to analyse and to optimise some new algorithms e.g. for Channel Estimation, Radio Resource Management, Vertical and Horizontal Handover procedures. Thus, the HIPERLAN/2 (H/2) protocol based on ETSI BRAN standard [2][3][4][5] has been chosen as basis for these purposes. Moreover, a Multi-Hop capability for H/2 using “Forwarder” concepts [6][7] will be introduced and be evaluated in this project. Timing issues are the most critical part in H/2 protocol development. This presentation provides a comprehensive overview of the development of performance critical communication systems such as H/2, the corresponding timing concepts for H/2 Mobile Terminal (MT) and Access Point (AP) protocols and the protocol implementation in a hard real time system [8]. As platform to run the H/2 protocols, an open source Linux based Personal Computer (PC), connected to the H/2 modem via a PCI interface, was chosen. An additional hardware unit called ROSA-Box (Radio Operation Service Accelerator) is used to provide a time critical support to the part of the H/2 MAC protocol. Since standard Linux operating system [9][10][11] provides only Round Robin scheduling which leads to poor support for real time systems, Real Time (RT) Linux [12], an open source real time operating system, is chosen to be the operating system for the H/2 protocol and since it fulfils the time critical requirements of the H/2 Protocol. On top of it, the H/2 protocols for both AP and MT will be formally specified in SDL (Specification and Description Language) [13][14]. Moreover, this presentation provides some implementation concepts of H/2 SDL protocol running in Real Time Linux kernel space as real time module, which is part of the real time operating system. Using RT Linux, the H/2 protocol has lower delay and lower interrupt latency. Moreover, this presentation introduces some concepts to optimise the processing power sharing among real time and non real time tasks.
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@INPROCEEDINGS{WiKl_SDLBoston01,
AUTHOR = {Wijaya, H. and Klein, O.},
TITLE = {H/2 SDL in Hard Real Time System},
JOURNAL = {The Third IEEE Workshop on Wireless Local Area Networks},
YEAR = {2001},
MONTH = {Sep},
VOLUME = {0},
ADDRESS = {Boston, USA},
AFFILIATION = {Department of Communication Networks (ComNets), Faculty 6, RWTH Aachen University},
ANNOTE = {ETSI, HiperLAN/2, Coverage, Demonstration Syste},
URL = {https://www.comnets.rwth-aachen.de}
}