46 research outputs found
Optimizing MDS Codes for Caching at the Edge
In this paper we investigate the problem of optimal MDS-encoded cache
placement at the wireless edge to minimize the backhaul rate in heterogeneous
networks. We derive the backhaul rate performance of any caching scheme based
on file splitting and MDS encoding and we formulate the optimal caching scheme
as a convex optimization problem. We then thoroughly investigate the
performance of this optimal scheme for an important heterogeneous network
scenario. We compare it to several other caching strategies and we analyze the
influence of the system parameters, such as the popularity and size of the
library files and the capabilities of the small-cell base stations, on the
overall performance of our optimal caching strategy. Our results show that the
careful placement of MDS-encoded content in caches at the wireless edge leads
to a significant decrease of the load of the network backhaul and hence to a
considerable performance enhancement of the network.Comment: to appear in Globecom 201
Low-Complexity Puncturing and Shortening of Polar Codes
In this work, we address the low-complexity construction of shortened and
punctured polar codes from a unified view. While several independent puncturing
and shortening designs were attempted in the literature, our goal is a unique,
low-complexity construction encompassing both techniques in order to achieve
any code length and rate. We observe that our solution significantly reduces
the construction complexity as compared to state-of-the-art solutions while
providing a block error rate performance comparable to constructions that are
highly optimized for specific lengths and rates. This makes the constructed
polar codes highly suitable for practical application in future communication
systems requiring a large set of polar codes with different lengths and rates.Comment: to appear in WCNC 2017 - "Polar Coding in Wireless Communications:
Theory and Implementation" Worksho
Band Codes for Energy-Efficient Network Coding with Application to P2P Mobile Streaming
A key problem in random network coding (NC) lies in the complexity and energy
consumption associated with the packet decoding processes, which hinder its
application in mobile environments. Controlling and hence limiting such factors
has always been an important but elusive research goal, since the packet degree
distribution, which is the main factor driving the complexity, is altered in a
non-deterministic way by the random recombinations at the network nodes. In
this paper we tackle this problem proposing Band Codes (BC), a novel class of
network codes specifically designed to preserve the packet degree distribution
during packet encoding, ecombination and decoding. BC are random codes over
GF(2) that exhibit low decoding complexity, feature limited and controlled
degree distribution by construction, and hence allow to effectively apply NC
even in energy-constrained scenarios. In particular, in this paper we motivate
and describe our new design and provide a thorough analysis of its performance.
We provide numerical simulations of the performance of BC in order to validate
the analysis and assess the overhead of BC with respect to a onventional NC
scheme. Moreover, peer-to-peer media streaming experiments with a random-push
protocol show that BC reduce the decoding complexity by a factor of two, to a
point where NC-based mobile streaming to mobile devices becomes practically
feasible.Comment: To be published in IEEE Transacions on Multimedi