In this paper we suggest a method by which reference broadcast
synchronization (RBS), and other methods of estimating clock values, can be
incorporated in standard clock synchronization algorithms to improve
synchronization quality. We advocate a logical separation of the task of
estimating the clock values of other nodes in the network from the task of
using these estimates to output a logical clock value.
The separation is achieved by means of a virtual estimate graph, overlaid on
top of the real network graph, which represents the information various nodes
can obtain about each other. RBS estimates are represented in the estimate
graph as edges between nodes at distance 2 from each other in the original
network graph. A clock synchronization algorithm then operates on the estimate
graph as though it were the original network.
To illustrate the merits of this approach, we modify a recent optimal
gradient clock synchronization algorithm to work in this setting. The modified
algorithm transparently takes advantage of RBS estimates and any other means by
which nodes can estimate each others' clock values.