  This paper studies caching in (K+L-1) x K partially connected wireless linear
networks, where each of the K receivers locally communicates with L out of the
K+L-1 transmitters, and caches are at all nodes. The goal is to design caching
and delivery schemes to reduce the transmission latency, by using normalized
delivery time (NDT) as the performance metric. For small transmitter cache size
(any L transmitters can collectively store the database just once), we propose
a cyclic caching strategy so that each of every L consecutive transmitters
caches a distinct part of each file; the delivery strategy exploits coded
multicasting and interference alignment by introducing virtual receivers. The
obtained NDT is within a multiplicative gap of 2 to the optimum in the entire
cache size region, and optimal in certain region. For large transmitter cache
size (any L transmitters can collectively store the database for multiple
copies), we propose a modified caching strategy so that every bit is repeatedly
cached at consecutive transmitters; the delivery strategy exploits
self-interference cancellation and interference neutralization. By combining
these schemes, the NDT is optimal in a larger region. We also extend our
results to linear networks with heterogeneous receiver connectivity and
partially connected circular networks.
