1,514 research outputs found
Fast Software Polar Decoders
Among error-correcting codes, polar codes are the first to provably achieve
channel capacity with an explicit construction. In this work, we present
software implementations of a polar decoder that leverage the capabilities of
modern general-purpose processors to achieve an information throughput in
excess of 200 Mbps, a throughput well suited for software-defined-radio
applications. We also show that, for a similar error-correction performance,
the throughput of polar decoders both surpasses that of LDPC decoders targeting
general-purpose processors and is competitive with that of state-of-the-art
software LDPC decoders running on graphic processing units.Comment: 5 pages, 3 figures, submitted to ICASSP 201
Flexible and Low-Complexity Encoding and Decoding of Systematic Polar Codes
In this work, we present hardware and software implementations of flexible
polar systematic encoders and decoders. The proposed implementations operate on
polar codes of any length less than a maximum and of any rate. We describe the
low-complexity, highly parallel, and flexible systematic-encoding algorithm
that we use and prove its correctness. Our hardware implementation results show
that the overhead of adding code rate and length flexibility is little, and the
impact on operation latency minor compared to code-specific versions. Finally,
the flexible software encoder and decoder implementations are also shown to be
able to maintain high throughput and low latency.Comment: Submitted to IEEE Transactions on Communications, 201
Partitioned Successive-Cancellation List Decoding of Polar Codes
Successive-cancellation list (SCL) decoding is an algorithm that provides
very good error-correction performance for polar codes. However, its hardware
implementation requires a large amount of memory, mainly to store intermediate
results. In this paper, a partitioned SCL algorithm is proposed to reduce the
large memory requirements of the conventional SCL algorithm. The decoder tree
is broken into partitions that are decoded separately. We show that with
careful selection of list sizes and number of partitions, the proposed
algorithm can outperform conventional SCL while requiring less memory.Comment: 4 pages, 6 figures, to appear at IEEE ICASSP 201
The 3.3 micron emission feature: Map of the galactic disk, 10 deg less than 1 less than 35 deg, - 6 deg less than b less than 6 deg
The 3.3 micron aromatic feature has been detected in the diffuse galactic emission with the AROME balloon-borne instrument. The results are presented in the form of an map of the 3.3 micron feature's intensity. The AROME instrument consists in a Cassegrain telescope with wobbling secondary mirrors and a liquid/solid nitrogen cooled photometer. The instrumental output is modified by the impulse response of the system. So the galactic surface brightness was restored in Fourier space by an inverse optimal filtering. The map of the feature's intensity is presented for a region of galactic coordinates. All the known H II giant molecular cloud complexes are visible in the 3.3 micron feature emission showing a good correlation with the infrared dust emission
A Sunyaev-Zel'dovich map of the massive core in the luminous X-ray cluster RXJ1347-1145
We have mapped the Sunyaev-Zel'dovich decrement (hereafter SZ) in the
direction of the most luminous X-ray cluster known to date, RXJ1347-1145, at
z=0.451. This has been achieved with an angular resolution of about 23'' using
the Diabolo photometer running on the IRAM 30 meter radio telescope. We present
here a map of the cluster central region at 2.1mm. The Comptonization parameter
towards the cluster center, \yc=(12.7^{+2.9}_{-3.1})\times 10^{-4},
corresponds to the deepest SZ decrement ever observed. Using the gas density
distribution derived from X-ray data, this measurement implies a gas
temperature \te=16.2 \pm 3.8 keV. The resulting total mass of the cluster is,
under hydrostatic equilibrium, for a corresponding gas fraction .Comment: 16 pages, 2 figures, accepted for publication in ApJ Letter
An Empirical Decomposition of Near-IR Emission into Galactic and Extragalactic Components
We decompose the COBE/DIRBE observations of the near-IR sky brightness (minus
zodiacal light) into Galactic stellar and interstellar medium (ISM) components
and an extragalactic background. This empirical procedure allows us to estimate
the 4.9 micron cosmic infrared background (CIB) as a function of the CIB
intensity at shorter wavelengths. A weak indication of a rising CIB intensity
at wavelengths > 3.5 micron hints at interesting astrophysics in the CIB
spectrum, or warns that the foreground zodiacal emission may be incompletely
subtracted. Subtraction of only the stellar component from the
zodiacal-light-subtracted all-sky map reveals the clearest 3.5 micron ISM
emission map, which is found to be tightly correlated with the ISM emission at
far-IR wavelengths.Comment: 10 pages. 10 JPEG and PNG figures. Uses emulateapj5.sty. To appear in
2003, ApJ, 585, 000 (March 1, 2003
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