16 research outputs found

    Unequal Error Protection Raptor Codes

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    We design Unequal Error Protection (UEP) Raptor codes with the UEP property provided by the precode part of Raptor codes which is usually a Low Density Parity Check (LDPC) code. Existing UEP Raptor codes apply the UEP property on the Luby transform (LT) code part of Raptor codes. This approach lowers the bit erasure rate (BER) of the more important bits (MIB) of the data decoded by the LT part of the decoder of Raptor code at the expense of degrading the BER performance of Less Important Bits (LIB), and hence the overall BER of the data passed from the LT part to the LDPC part of the decoder is higher compared to the case of using an Equal Error Protection (EEP) LT code. The proposed UEP Raptor code design has the structure of UEP LDPC code and EEP LT code so that it has the advantage of passing data blocks with lower BER from the LT code part to the LDPC code part of the decoder. This advantage is translated into improved performance in terms of required overhead and achieved BER on both the MIB bits and LIB bits of the decoded data compared to UEP Raptor codes applying the UEP property on the LT part. We propose two design schemes. The first combines a partially regular LDPC code which has UEP properties with an EEP LT code, and the second scheme uses two LDPC codes with different code rates in the precode part such that the MIB bits are encoded using the LDPC code with lower rate and the LT part is EEP. Simulations of both designs exhibit improved BER performance on both the MIB bits and LIB bits while consuming smaller overheads. The second design can be used to provide unequal protection for cases where the MIB bits comprise a fraction of more than 0.4 of the source data which is a case where UEP Raptor codes with UEP LT codes perform poorly

    A polar codes-based distributed UEP scheme for the internet of things

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    The Internet of Things (IoT), which is expected to support a massive number of devices, is a promising communication scenario. Usually, the data of different devices has different reliability requirements. Channel codes with the unequal error protection (UEP) property are rather appealing for such applications. Due to the power-constrained characteristic of the IoT services, most of the data has short packets; therefore, channel codes are of short lengths. Consequently, how to transmit such nonuniform data from multisources efficiently and reliably becomes an issue be solved urgently. To address this issue, in this paper, a distributed coding scheme based on polar codes which can provide UEP property is proposed. The distributed polar codes are realized by the groundbreaking combination method of noisy coded bits. With the proposed coding scheme, the various data from multisources can be recovered with a single common decoder. Various reliability can be achieved; thus, UEP is provided. Finally, the simulation results show that the proposed coding scheme is viable

    Historical information aware unequal error protection of scalable HEVC/H.265 streaming over free space optical channels

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    Free space optical (FSO) systems are capable of supporting high data rates between fixed points in the context of flawless video communications. Layered video coding facilitates the creation of different-resolution subset layers for variablethroughput transmission scenarios. In this paper, we propose Historical information Aware Unequal Error Protection (HAUEP) for the scalable high efficiency video codec (SHVC) used for streaming over FSO channels. Specifically, the objective function (OF) of the current video frame is designed based on historical information of its dependent frames. By optimizing this OF, specific subset layers may be selected in conjunction with carefully selected forward error correction (FEC) coding rates, where the expected video distortion is minimized and the required bitrate is reduced under the constraint of a specific throughput. Our simulation results show that the proposed system outperforms the traditional equal error protection (EEP) scheme by about 4.5 dB of Eb=N0 at a peak signal-to-noise ratio (PSNR) of 33 dB. From a throughput-oriented perspective, HA-UEP is capable of reducing the throughput to about 30% compared to that of the EEP benchmarker, while achieving an Eb=N0 gain of 4.5 dB
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