  Payment channel networks (PCNs) are a promising technology to improve the
scalability of cryptocurrencies. PCNs, however, face the challenge that the
frequent usage of certain routes may deplete channels in one direction, and
hence prevent further transactions. In order to reap the full potential of
PCNs, recharging and rebalancing mechanisms are required to provision channels,
as well as an admission control logic to decide which transactions to reject in
case capacity is insufficient. This paper presents a formal model of this
optimisation problem. In particular, we consider an online algorithms
perspective, where transactions arrive over time in an unpredictable manner.
Our main contributions are competitive online algorithms which come with
provable guarantees over time. We empirically evaluate our algorithms on
randomly generated transactions to compare the average performance of our
algorithms to our theoretical bounds. We also show how this model and approach
differs from related problems in classic communication networks.
