Network Coding: Connections Between Information Theory And Estimation Theory

In this paper, we prove the existence of fundamental relations between information theory and estimation theory for network-coded flows. When the network is represented by a directed graph G=(V, E) and under the assumption of uncorrelated noise over information flows between the directed links connecting transmitters, switches (relays), and receivers. We unveil that there yet exist closed-form relations for the gradient of the mutual information with respect to different components of the system matrix M. On the one hand, this result opens a new class of problems casting further insights into effects of the network topology, topological changes when nodes are mobile, and the impact of errors and delays in certain links into the network capacity which can be further studied in scenarios where one source multi-sinks multicasts and multi-source multicast where the invertibility and the rank of matrix M plays a significant role in the decoding process and therefore, on the network capacity. On the other hand, it opens further research questions of finding precoding solutions adapted to the network level.Comment: IEEE Wireless Communications and Networking Conference (WCNC), April, 201

Piggybacking Codes for Network Coding: The High/Low SNR Regime

We propose a piggybacking scheme for network coding where strong source inputs piggyback the weaker ones, a scheme necessary and sufficient to achieve the cut-set upper bound at high/low-snr regime, a new asymptotically optimal operational regime for the multihop Amplify and Forward (AF) networks

Network Coding Power Control Mechanisms for Time Varying Channels

In this paper, we propose a model for large scale fading channels via markov process. We exploit the channel delay profile and the dependency between channel states via a first order autoregressive model that cast insight to the channel variations under fading and the closed form delay induced. We propose a network-coding structure that can be employed to compensate for the channel variations under fixed power and to the period of zero packet transmissions under adaptive power control. Satellite communications is an application to the model proposed

ANTI-MICROBIAL EVALUATION OF NEW THIAZOLO PYRIMIDINE DERIVATIVES

Twelve new heterocyclic compounds containing thiazolo pyrimidine moiety were thus synthesized.. Compound 2 was synthesized by reaction of α-amino naphthol 1 with potassium isothiocyanate. Reaction of compound 2 with sodium nitrite and hydrochloric acid afforded the corresponding diazonuim salt 3, which converted to 2-hydrazino thiazolo derivatives 4. Compound 2 carried out to synthesize imidazolo thiazolo derivative 5, 6 and thiazolo pyrimidino derivative 7, 8 and 9 respectively. Compound 4 was carried out to synthesize of compound 10. Compound 10 was carried out to synthesize of triazolo thiazolo and thiadiazolo derivatives 11 and 12 respectively. The structures of all newly synthesized compounds were elucidated by elemental analysis, IR, 1H-NMR and mass spectral data. The assignments of the new products were tested for Anti-microbial activities. Results are suggesting thiazolo pyrimidine derivatives emerge as valuable compounds with great potential to be used as antibacterial and antifungal agents, and as promising candidates for further efficiency evaluation. The detailed synthesis, spectroscopic data and Anti-microbial activities are reported

Energy Efficient Adaptive Network Coding Schemes for Satellite Communications

In this paper, we propose novel energy efficient adaptive network coding and modulation schemes for time variant channels. We evaluate such schemes under a realistic channel model for open area environments and Geostationary Earth Orbit (GEO) satellites. Compared to non-adaptive network coding and adaptive rate efficient network-coded schemes for time variant channels, we show that our proposed schemes, through physical layer awareness can be designed to transmit only if a target quality of service (QoS) is achieved. As a result, such schemes can provide remarkable energy savings.Comment: Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 24 March 201

Network Coding Channel Virtualization Schemes for Satellite Multicast Communications

In this paper, we propose two novel schemes to solve the problem of finding a quasi-optimal number of coded packets to multicast to a set of independent wireless receivers suffering different channel conditions. In particular, we propose two network channel virtualization schemes that allow for representing the set of intended receivers in a multicast group to be virtualized as one receiver. Such approach allows for a transmission scheme not only adapted to per-receiver channel variation over time, but to the network-virtualized channel representing all receivers in the multicast group. The first scheme capitalizes on a maximum erasure criterion introduced via the creation of a virtual worst per receiver per slot reference channel of the network. The second scheme capitalizes on a maximum completion time criterion by the use of the worst performing receiver channel as a virtual reference to the network. We apply such schemes to a GEO satellite scenario. We demonstrate the benefits of the proposed schemes comparing them to a per-receiver point-to-point adaptive strategy