4,887 research outputs found
Mutual Information-Maximizing Quantized Belief Propagation Decoding of Regular LDPC Codes
In mutual information-maximizing lookup table (MIM-LUT) decoding of
low-density parity-check (LDPC) codes, table lookup operations are used to
replace arithmetic operations. In practice, large tables need to be decomposed
into small tables to save the memory consumption, at the cost of degraded error
performance. In this paper, we propose a method, called mutual
information-maximizing quantized belief propagation (MIM-QBP) decoding, to
remove the lookup tables used for MIM-LUT decoding. Our method leads to a very
efficient decoder, namely the MIM-QBP decoder, which can be implemented based
only on simple mappings and fixed-point additions. Simulation results show that
the MIM-QBP decoder can always considerably outperform the state-of-the-art
MIM-LUT decoder, mainly because it can avoid the performance loss due to table
decomposition. Furthermore, the MIM-QBP decoder with only 3 bits per message
can outperform the floating-point belief propagation (BP) decoder at high
signal-to-noise ratio (SNR) regions when testing on high-rate codes with a
maximum of 10-30 iterations
A Novel Location Free Link Prediction in Multiplex Social Networks
In recent decades, the emergence of social networks has enabled internet
service providers (e.g., Facebook, Twitter and Uber) to achieve great
commercial success. Link prediction is recognized as a common practice to build
the topology of social networks and keep them evolving. Conventionally, link
prediction methods are dependent of location information of users, which
suffers from information leakage from time to time. To deal with this problem,
companies of smart devices (e.g., Apple Inc.) keeps tightening their privacy
policy, impeding internet service providers from acquiring location
information. Therefore, it is of great importance to design location free link
prediction methods, while the accuracy still preserves. In this study, a novel
location free link prediction method is proposed for complex social networks.
Experiments on real datasets show that the precision of our location free link
prediction method increases by 10 percent
Periodicities in the occurrence of aurora as indicators of solar variability
A compilation of records of the aurora observed in China from the Time of the Legends (2000 - 3000 B.C.) to the mid-18th century has been used to infer the frequencies and strengths of solar activity prior to modern times. A merging of this analysis with auroral and solar activity patterns during the last 200 years provides basically continuous information about solar activity during the last 2000 years. The results show periodicities in solar activity that contain average components with a long period (approx. 412 years), three middle periods (approx. 38 years, approx. 77 years, and approx. 130 years), and the well known short period (approx. 11 years)
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