Green's functions technique for calculating the emission spectrum in a quantum dot-cavity system

We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems. In particular, we investigate the potential of this theoretical approach by its application to compute the emission spectrum of a dissipative system composed by a single quantum dot inside of a semiconductor cavity. We also describe a simple algorithm based on the Green's functions technique for calculating the emission spectrum of the quantum dot as well as of the cavity which can easily be implemented in any numerical linear algebra package. We find that the Green's functions technique demonstrates a better accuracy and efficiency in the calculation of the emission spectrum and it allows to overcome the inherent theoretical difficulties associated to the direct application of the quantum regression theorem approach

Degraded Broadcast Channel with Side Information, Confidential Messages and Noiseless Feedback

In this paper, first, we investigate the model of degraded broadcast channel with side information and confidential messages. This work is from Steinberg's work on the degraded broadcast channel with causal and noncausal side information, and Csisz$\acute{a}$r-K\"{o}rner's work on broadcast channel with confidential messages. Inner and outer bounds on the capacity-equivocation regions are provided for the noncausal and causal cases. Superposition coding and double-binning technique are used in the corresponding achievability proofs. Then, we investigate the degraded broadcast channel with side information, confidential messages and noiseless feedback. The noiseless feedback is from the non-degraded receiver to the channel encoder. Inner and outer bounds on the capacity-equivocation region are provided for the noncausal case, and the capacity-equivocation region is determined for the causal case. Compared with the model without feedback, we find that the noiseless feedback helps to enlarge the inner bounds for both causal and noncausal cases. In the achievability proof of the feedback model, the noiseless feedback is used as a secret key shared by the non-degraded receiver and the transmitter, and therefore, the code construction for the feedback model is a combination of superposition coding, Gel'fand-Pinsker's binning, block Markov coding and Ahlswede-Cai's secret key on the feedback system.Comment: Part of this paper has been accepted by ISIT2012, and this paper is submitted to IEEE Transactions on Information Theor

Interleaving and nulling to combat narrow-band interference in PLC standard technologies PLC G3 and PRIME

Three functional blocks of the PRIME and PLC G3 technologies (encoder/decoder, interleaver, and modulator) are studied in detail, for a PLC channel with narrow-band interference (NBI). The study reveals that these three blocks can be used together effectively so as to improve the performance of the overall system in the presence of NBI. We therefore present effective methods for combating NBI in PRIME and PLC G3, based on these three functional blocks

Waveform clipping in FSK modulated signal to combat impulse noise

Abstract: This article presents results on the pre-processing (clipping/nulling) of impulse noise corrupted signal that is digitally modulated. The novelty of the article is in performing the clipping technique on the waveform of the digitally modulated signal as opposed to working with the constellation of the modulated signal. We present bit error rate performance results of Frequency Shift Keying (FSK) modulation in the presence of impulse noise and AWGN, when clipping is performed. We furthermore, develop closed-form expressions for the bit error rates of FSK modulation in the presence of both AWGN and impulse noise, when clipping of the received signal has been performed

Reed-Solomon code symbol avoidance

A Reed-Solomon code construction that avoids or excludes particular symbols in a linear Reed-Solomon code is presented. The resulting code, from our symbol avoidance construction, has the same or better error-correcting capabilities compared to the original Reed-Solomon code, but with reduced efficiency in terms of rate. The codebook of the new code is a subset of the original Reed-Solomon code and the code may no longer be linear. We also present computer search results for the bound on the number of symbols that can be avoided, and we make an attempt to find an expression for the bound. Such a code, by symbol avoidance, can be well suited to a number of applications, some of which include markers for synchronization, frequency hopping signatures, and pulse position modulation