  We consider a line of terminals which is connected by packet erasure channels
and where random linear network coding is carried out at each node prior to
transmission. In particular, we address an online approach in which each
terminal has local information to be conveyed to the base station at the end of
the line and provide a queueing theoretic analysis of this scenario. First, a
genie-aided scenario is considered and the average delay and average
transmission energy depending on the link erasure probabilities and the Poisson
arrival rates at each node are analyzed. We then assume that all nodes cannot
send and receive at the same time. The transmitting nodes in the network send
coded data packets before stopping to wait for the receiving nodes to
acknowledge the number of degrees of freedom, if any, that are required to
decode correctly the information. We analyze this problem for an infinite queue
size at the terminals and show that there is an optimal number of coded data
packets at each node, in terms of average completion time or transmission
energy, to be sent before stopping to listen.
