  This paper proposes a mobile pipeline computing concept in a Device-to-Device
(D2D) communication setup and studies related issues, where D2D is likely based
on millimeter-wave (mmWave) in the 5G mobile communication. The proposed
opportunistic system employs a cluster of pipelined resource-limited devices on
the move to handle real-time on-site computation-intensive tasks for which
current cloud computing technology may not be suitable. The feasibility of such
a system can be anticipated as high-speed and low-latency wireless technologies
get mature. We present a system model by defining the architecture, basic
functions, processes at both system-level and pipeline device level. A pipeline
pathfinding algorithm along with a multi-task optimization framework is
developed. To minimize the search space since the algorithm may need to be run
on resource-limited mobile devices, an adjacency-matrix-power-based graph
trimming technique is proposed and validated using simulation. A preliminary
feasibility assessment of our proposed techniques is performed using
experiments and computer simulation. As part of the feasibility assessment, the
impact of mmWave blockage on the pipeline stability is analyzed and examined
for both single-pipeline and concurrent-multiple-pipeline scenarios. Our design
and analysis results provide certain insight to guide system design and lay a
foundation for further work in this line.
