Many network protocols for embedded systems rely on temporal   partitions to provide isolation between different nodes (TDMA   slots) or different traffic classes (multi-phase cyclic   frameworks). Typically, the duration of the slots or phases is not   correlated with the duration of packet transmissions, which is   variable and non-preemptive. Thus, it is possible that the limit   of the slot or phase be overrun by an on-going packet transmission  or, if this cannot be tolerated, idle-time must be inserted at the  end of the slot or phase whenever a packet does not fit in. The  former solution is common in multi-phase cyclic frameworks while  the latter is typical in TDMA buses. Nevertheless, both situations  lead to scheduling anomalies in which the worst-case network delay  does not occur with the synchronous release of all other packets,  or just the higher priority ones. This presentation highlights  some of these anomalies showing their origin and indicating that  it is not possible to determine the worst-case network delay with exactitude in the  general case. However, it is still possible to upper bound the network delay and the paper shows a non-optimal solution for those cases.

 Bio:

Luis Almeida is currently a professor of the Electronics, Telecommunications and Informatics Department (DETI) of the Universidade de Aveiro (UA), and Coordinator of the LSE (http:// www.ieeta.pt/lse), a research laboratory of the IEETA research unit (Instituto de Engenharia Electrónica e Telemática de Aveiro)  at the same university. He belongs to the Scientific Board of  IEETA and he is a senior member of the IEEE, Computer Society.  Luis Almeida has coordinated the LSE since 2003, being currently  interested in real-time communication protocols for embedded  systems with an emphasis on mechanisms to support predicatble  operational flexibility. He is a co-author of more than 80  refereed publications in international scientific conferences and  journals in the area, and co-author of 3 patents and 3 book  chapters. He has given several invited talks and short courses  about related topics and supervised several PhD students and Post- Doc visits to the LSE. He regularly participates in the organization of scientific events in the Real-Time Systems and Robotics communities.

Tuesday, Novemebr 14th, 2006

3:30 am - 5:00noon

307 Levine Hall