3 research outputs found
Fountain Codes with Nonuniform Selection Distributions through Feedback
One key requirement for fountain (rateless) coding schemes is to achieve a
high intermediate symbol recovery rate. Recent coding schemes have incorporated
the use of a feedback channel to improve intermediate performance of
traditional rateless codes; however, these codes with feedback are designed
based on uniformly at random selection of input symbols. In this paper, on the
other hand, we develop feedback-based fountain codes with dynamically-adjusted
nonuniform symbol selection distributions, and show that this characteristic
can enhance the intermediate decoding rate. We provide an analysis of our
codes, including bounds on computational complexity and failure probability for
a maximum likelihood decoder; the latter are tighter than bounds known for
classical rateless codes. Through numerical simulations, we also show that
feedback information paired with a nonuniform selection distribution can highly
improve the symbol recovery rate, and that the amount of feedback sent can be
tuned to the specific transmission properties of a given feedback channel.Comment: Submitted to the IEEE Transactions on Information Theor
Delay-Efficient and Reliable Data Relaying in Ultra Dense Networks using Rateless Codes
We investigate the problem of delay-efficient and reliable data delivery in
ultra-dense networks (UDNs) that constitute macro base stations (MBSs), small
base stations (SBSs), and mobile users. Considering a two-hop data delivery
system, we propose a partial decode-and-forward (PDF) relaying strategy
together with a simple and intuitive amicable encoding scheme for rateless
codes to significantly improve user experience in terms of end-to-end delay.
Simulation results verify that our amicable encoding scheme is efficient in
improving the intermediate performance of rateless codes. It also verifies that
our proposed PDF significantly improves the performance of the
decode-and-forward (DF) strategy, and that PDF is much more robust against
channel degradation. Overall, the proposed strategy and encoding scheme are
efficient towards delay-sensitive data delivery in the UDN scenarios.Comment: Accepted for presentation at the IEEE Global Communications
Conference (GLOBECOM) 202
Design and Analysis of Online Fountain Codes for Intermediate Performance
For the benefit of improved intermediate performance, recently online
fountain codes attract much research attention. However, there is a trade-off
between the intermediate performance and the full recovery overhead for online
fountain codes, which prevents them to be improved simultaneously. We analyze
this trade-off, and propose to improve both of these two performance. We first
propose a method called Online Fountain Codes without Build-up phase (OFCNB)
where the degree-1 coded symbols are transmitted at first and the build-up
phase is removed to improve the intermediate performance. Then we analyze the
performance of OFCNB theoretically. Motivated by the analysis results, we
propose Systematic Online Fountain Codes (SOFC) to further reduce the full
recovery overhead. Theoretical analysis shows that SOFC has better intermediate
performance, and it also requires lower full recovery overhead when the channel
erasure rate is lower than a constant. Simulation results verify the analyses
and demonstrate the superior performance of OFCNB and SOFC in comparison to
other online fountain codes