Topics in Distributed Algorithms: On TDMA for Ad Hoc Networks and Coded Atomic Storage Algorithms
Distributed algorithms run on a network of nodes. The nodes are running
concurrently and are independent from each other. Furthermore, they have their own
instructions and information. In this context, the challenges are to show that
the algorithm is correct, regardless of computational, or communication delays.
Furthermore, the behavior after transient faults and under the existence of
Byzantine nodes is of our interest.
This thesis discusses fundamental communication models for distributed algorithms.
These models are implementing abstract communication methods.
First we address medium access control for a wireless medium with guarantees
on the communication delay. We discuss time division multiple access
protocols for ad-hoc networks and we introduce an algorithm that creates a
TDMA schedule without
using external references for localization, or time. This algorithm recovers
from transient faults and is self-stabilizing. The TDMA schedule provides
guarantees on the delivery time. This enables the use of this algorithm as MAC
layer for safety critical applications. Furthermore, we provide bounds for the
The second topic is the emulation of shared memory on message passing
networks. Both, shared memory and message passing are basic interprocessor
communication models for distributed algorithms. We are providing a way of
emulating shared memory on top of an existing message passing network under
the presence of data corruption and stop-failed nodes. Additionally, we ensure
the privacy of the data that is stored in the shared memory.
Time Division Multiple Access