  One of the key technologies for future IoT/M2M systems are low power wide
area networks, which are designed to support a massive number of low-end
devices often in the unlicensed shared spectrum using random access protocols.
However these usually operate without centralised control and since Automatic
Repeat request and acknowledgement mechanisms are not very effective due to the
strict duty cycles limits and high interference in the shared bands, many
packets are lost from collisions. In this paper we analyse a recently proposed
application layer coding scheme, which aims to recover lost packets by
introducing redundancy in the form of a fountain code. We show how latency and
decoding complexity is affected by the packet loss rate but also prove that
there is a limit to what can be achieved by introducing more redundancy. The
analysis is backed up by simulation results.
