Fountain coding with decoder side information

In this contribution, we consider the application of Digital Fountain (DF) codes to the problem of data transmission when side information is available at the decoder. The side information is modelled as a "virtual" channel output when original information sequence is the input. For two cases of the system model, which model both the virtual and the actual transmission channel either as a binary erasure channel or as a binary input additive white Gaussian noise (BIAWGN) channel, we propose methods of enhancing the design of standard non-systematic DF codes by optimizing their output degree distribution based oil the side information assumption. In addition, a systematic Raptor design has been employed as a possible solution to the problem

Polar Coding for Fading Channels

A polar coding scheme for fading channels is proposed in this paper. More specifically, the focus is Gaussian fading channel with a BPSK modulation technique, where the equivalent channel could be modeled as a binary symmetric channel with varying cross-over probabilities. To deal with variable channel states, a coding scheme of hierarchically utilizing polar codes is proposed. In particular, by observing the polarization of different binary symmetric channels over different fading blocks, each channel use corresponding to a different polarization is modeled as a binary erasure channel such that polar codes could be adopted to encode over blocks. It is shown that the proposed coding scheme, without instantaneous channel state information at the transmitter, achieves the capacity of the corresponding fading binary symmetric channel, which is constructed from the underlying fading AWGN channel through the modulation scheme.Comment: 6 pages, 4 figures, conferenc

Polar Codes over Fading Channels with Power and Delay Constraints

The inherent nature of polar codes being channel specific makes it difficult to use them in a setting where the communication channel changes with time. In particular, to be able to use polar codes in a wireless scenario, varying attenuation due to fading needs to be mitigated. To the best of our knowledge, there has been no comprehensive work in this direction thus far. In this work, a practical scheme involving channel inversion with the knowledge of the channel state at the transmitter, is proposed. An additional practical constraint on the permissible average and peak power is imposed, which in turn makes the channel equivalent to an additive white Gaussian noise (AWGN) channel cascaded with an erasure channel. It is shown that the constructed polar code could be made to achieve the symmetric capacity of this channel. Further, a means to compute the optimal design rate of the polar code for a given power constraint is also discussed.Comment: 6 pages, 6 figure

Quantum channels from reflections on moving mirrors

Light reflection on a mirror can be thought as a simple physical effect. However if this happens when the mirror moves a rich scenario opens up. Here we aim at analyzing it from a quantum communication perspective. In particular, we study the kind of quantum channel that arises from (Gaussian) light reflection upon an accelerating mirror. Two competing mechanisms emerge in such a context, namely photons production by the mirror's motion and {\blu interference between modes}. As consequence we find out a quantum amplifier channel and quantum lossy channel respectively below and above a threshold frequency (that depends on parameters determining mirror's acceleration). Exactly at the threshold frequency the channel behaves like a purely classical additive channel, while it becomes purely erasure for large frequencies. In addition the time behavior of the channel is analyzed by employing wave packets expansion of the light field.Comment: 12 pages, 3 figure

Low-Complexity Erasure Insertion in Frequency-Hopping Spread-Spectrum Communications Subjected to Fading and Partial-Band Interference

In this paper we propose two novel low-complexity, low-delay erasure insertion schemes, namely the Output Threshold Test (OTT) and joint Maximum Output and Ratio Threshold Test (MO-RTT). The employment of the OTT and MO-RTT is beneficial in the context of the ‘Errors-And-Erasures (EAE)’ Reed-Solomon (RS) decoding in a Slow Frequency-Hopping based Spread-Spectrum (SFH/SS) system using $M$-ary Frequency-Shift Keying (MFSK). The statistics of the erasure insertion related decision variables associated with the OTT, MO-RTT as well as with the Ratio Threshold Test (RTT) are investigated, when the channel of each FH slot is modeled as flat Nakagami-$M$ fading. The transmitted signals also experience both Additive White Gaussian Noise (AWGN) as well as Partial-Band Gaussian Interference (PBGI). The performance of the proposed erasure insertion schemes and that of the erasure insertion scheme using the RTT is investigated and compared in the context of RS coded SFH/SS systems using MFSK modulation