  Spectrum sharing has long been considered as method to improve spectrum
resource utilization. Centralized geolocation database approach has been
accepted globally for commercial applications. Recently blockchain has been
considered as a platform to support spectrum sharing in a distributed manner.
Like other commodities, spectrum or right of spectrum usage can be exchanged
through blockchain. However, this leads to changes of the location where a
particular frequency channel is utilized which brings potential interference.
In this paper, we present the interference based consensus and smart contract
for blockchain based spectrum sharing. We will also introduce the other aspects
of blockchain such as cross train transaction, cross tier spectrum coordination
and incentive mechanism that need to be studied for spectrum sharing
applications.
