Leveraging Start of Frame Delimiter (SFD) for in-parallel communication in large systems
Leveraging Start of Frame Delimiter (SFD) for in-parallel communication in large systems
Embedded Files
Abstract:
Abstract:
Start of Field Delimiter (SFD) is a very well-known parameter in physical layer packet formats available in most of the communication technologies. SFD serves as a marker to indicate the beginning of the packet content. Thus, changing the default SFD can hide wireless transmission among different groups. In this work we demonstrate that this simple physical layer parameter in addition to serving its original purpose can also be used as an alternative for in-parallel communication in large systems. Through empirical and analytical studies we demonstrate that change of SFD along with appropriate use of synchronous transmission can bring the desired effect. Through extensive evaluation we showed the success of the proposed strategy in multiple testbed systems.
Key idea and results
Key idea and results
Packet structure of Physical Layer Data Unit
What is SFD?
What is SFD?
It is a 1-byte field that is transmitted before the actual frame header to indicate that the upcoming bits are the start of a frame (see the figure on the left). Frame reception starts when the right SFD bit pattern is detected. SFD is 8 bits long, so we have the possibility of using 255 different SFDs for parallel communication. But not all are usable.
Inter-Group Separation using SFDs
SFDs for inter-group separation
SFDs for inter-group separation
In the context of inter-group separation, the naive solution using SFD can be done by assigning different SFDs to different groups so that communication in one group is not visible in the other. As the first scenario in the figure on the left shows that all the nodes are working with the default SFDs, whereas in the second scenario nodes are separated into groups and we assign two different SFDs to the two different groups. Thus, in the second scenario, the inter-group communications would not be visible to the nodes.
Result showing the improvement
Result
Result
We did a rigorous study of in-parallel execution using three protocols, e.g., with SFD change, without SFD change, and with channel change and no SFD change. Through rigorous experiments on various types of group divisions over real WSN/IoT systems, we show that the strategy with SFD change performs up to 60% (more than 2 times) better than without SFD change in terms of reliability while sacrificing some amount of time with respect to the ideal channel change strategy.
Relevant publications:
Relevant publications:
Start of Frame Delimiters (SFDs) for Simultaneous Intra-Group One-to-All Dissemination. Jagnyashini Debadarshini, Sudipta Saha, Olaf Landsiedel, and Mun Chun Chan. In Proceedings of the 45th IEEE International Conference on Local Computer Networks (LCN), 2020, Sydney, Australia. [IEEE LCN 2020] [PDF]
Page updated
Report abuse