  This article considers the problem of delay optimal bundling of the input
symbols into transmit packets in the entry point of a wireless sensor network
such that the link delay is minimized under an arbitrary arrival rate and a
given channel error rate. The proposed policy exploits the variable packet
length feature of contemporary communications protocols in order to minimize
the link delay via packet length regularization. This is performed through
concrete characterization of the end-to-end link delay for zero error tolerance
system with First Come First Serve (FCFS)queuing discipline and Automatic
Repeat Request (ARQ) retransmission mechanism. The derivations are provided for
an uncoded system as well as a coded system with a given bit error rate. The
proposed packetization policy provides an optimal packetization interval that
minimizes the end-to-end delay for a given channel with certain bit error
probability. This algorithm can also be used for near-optimal bundling of input
symbols for dynamic channel conditions provided that the channel condition
varies slowly over time with respect to symbol arrival rate. This algorithm
complements the current network-based delay-optimal routing and scheduling
algorithms in order to further reduce the end-to-end delivery time. Moreover,
the proposed method is employed to solve the problem of energy efficiency
maximization under an average delay constraint by recasting it as a convex
optimization problem.
