Sebastian Magierowski

Optimum receiver for molecule shift keying modulation in diffusion-based molecular communication channels

Abstract Designing an optimum receiver for diffusion-based molecular communication in nano-networks needs a well justified channel model. In this paper, we present a linear and time invariant signal propagation model and an additive noise model for the diffusion-based molecular communication channel. These models are based on Brownian motion molecular statistics. Using these models, we develop the first optimal receiver design for diffusion-based molecular communication scenarios with and without inter-symbol interference. We evaluate the performance of our proposed receiver by investigating the bit error rate for small and large transmission rates.

Blind Synchronization in Diffusion-Based Molecular Communication Channels

Synchronization is an essential feature of any communication system. Due to the very low throughput of molecular communications systems, blind synchronization is preferred in order to reduce communications overhead. In this paper, we present the first blind synchronization algorithm for the diffusion-based molecular communication channel. Considering a diffusion-based physical channel model, we use the non-decision directed maximum likelihood criterion for estimating the channel delay. We then derive the Cramer-Rao lower bound and evaluate the performance of the proposed synchronization algorithm by investigating its mean square error.

CMOS LC-oscillator phase-noise analysis using nonlinear models

In this paper, a second-order stochastic differential equation is used as a tool for the analysis of phase noise in a submicron CMOS LC oscillator. A cross-coupled topology typical of integrated CMOS designs is considered. Nonlinear limiting and mobility degradation effects in the circuit are modeled and used to predict the statistics of the random amplitude and phase deviations in terms of design variables. Assuming Gaussian noise disturbances and describing the phase noise as a random diffusion process, the average phase-noise power spectrum is derived and its accuracy verified with measurement and simulation results. Calculations for phase noise arising from stationary tank noise, nonstationary channel thermal noise, and flicker noise are discussed. The analysis is used to emphasize the fundamental power/performance tradeoff associated with compensation of tank losses via adjustments in the power supply and device size.

Vehicle Routing Problems for Drone Delivery

Unmanned aerial vehicles, or drones, have the potential to significantly reduce the cost and time of making last-mile deliveries and responding to emergencies. Despite this potential, little work has gone into developing vehicle routing problems (VRPs) specifically for drone delivery scenarios. Existing VRPs are insufficient for planning drone deliveries: either multiple trips to the depot are not permitted, leading to solutions with excess drones, or the effect of battery and payload weight on energy consumption is not considered, leading to costly or infeasible routes. We propose two multitrip VRPs for drone delivery that address both issues. One minimizes costs subject to a delivery time limit, while the other minimizes the overall delivery time subject to a budget constraint. We mathematically derive and experimentally validate an energy consumption model for multirotor drones, demonstrating that energy consumption varies approximately linearly with payload and battery weight. We use this approximation to derive mixed integer linear programs for our VRPs. We propose a cost function that considers our energy consumption model and drone reuse, and apply it in a simulated annealing (SA) heuristic for finding suboptimal solutions to practical scenarios. To assist drone delivery practitioners with balancing cost and delivery time, the SA heuristic is used to show that the minimum cost has an inverse exponential relationship with the delivery time limit, and the minimum overall delivery time has an inverse exponential relationship with the budget. Numerical results confirm the importance of reusing drones and optimizing battery size in drone delivery VRPs.

Nano-machine molecular communication over a moving propagation medium

Abstract In this paper, we study a molecular communication system operating over a moving propagation medium. Using the convection–diffusion equation, we present the first separate models for the channel response and the corrupting noise. The flow-based molecular channel is shown to be linear but time-varying and the noise corrupting the signal is additive white Gaussian with a signal dependent magnitude. By modelling the ligand–receptor binding process, it is shown that the molecular communication reception process in this channel has a low-pass characteristic that colours the additive noise. A whitening filter is proposed to compensate for this low-pass characteristic. Simulation results demonstrate the benefit of the whitening filter and the effect of medium motion on bit error rate.

Joint Fading and Shadowing Model for Large Office Indoor WLAN Environments

This paper presents measurements and a propagation model for an indoor wireless LAN (WLAN) scenario that represents an open concept office or laboratory layout with few large obstacles to reflect and refract the transmitted signal. Most mobile WLAN users generally restrict their movements to a small area due to the inability of most WLANs to accommodate hand-offs. As a result, users travel through at most one or two scattering clusters and experience only one or two discrete shadowing values. Hence, this paper will use propagation measurements collected over bandwidths of 10 MHz, to develop a statistical model for shadowing suitable for such an indoor WLAN scenario. Moreover, in indoor environments shadowing varies quickly enough to require some channel estimation algorithms to account for both small scale and large scale statistics. Therefore, this paper will present a distribution that jointly models variations due to both Rician fading and the new shadowing model. An analytical expression for the probability density function (PDF) of the joint distribution will be derived and fit to the experimental propagation data.

RF CMOS Parametric Downconverters

Parametric amplifiers are absent today from the majority of electronics applications. This is especially the case for parametric downconverters (PDCs). Coupled with the increasing emphasis on millimeter-wave applications and the cost of transistor scaling, the time may be right to reconsider these circuits. By employing coupled-mode theory, we arrive at a general description of PDCs. Consequently, a simple mixer is proposed that achieves gain at reduced pumping frequencies without resorting to sub-harmonics. The implications of this design for quadrature receiver systems are shown. Fundamental gain and noise limits are derived indicating the ability to operate at sub-5-dB noise figures (NFs) with very low-power requirements. Measurements on an accumulation-mode varactor in 130-nm CMOS technology indicate the necessary pumping and biasing regimes needed to approach these limits. Finally, a compact 30-GHz PDC design with 2-dB NF is discussed.

Fading Statistics for the Joint Fading and Two Path Shadowing Channel

New expressions for the joint moments, mean, variance and amount of fading (AF) of the Joint Fading and Two-path Shadowing (JFTS) distribution are derived in this letter. The derived expressions for theoretical mean and variance are shown to agree with the experimental results. The AF expression is used for comparing the severity of fading imparted by the JFTS distribution to the fading severity of other common small scale fading and composite fading / shadowing distributions.

Modelling the reception process in diffusion-based molecular communication channels

Implementing a realistic communication system using a diffusion-based molecular channel requires a well justified model for the reception process at the receiver nano-machine. In this paper, we model the reception process at a receiver nano-machine by means of ligand-receptor binding kinetics. For this purpose, we use a diffusion-based physical channel model and we show that the reception process can be interpreted as a low-pass filter. Then, we evaluate the effect of the reception process on the statistical characteristics of the noise added by the diffusion channel. In order to suppress the effect of the ligand-receptor binding process, we design a whitening filter which is placed before the demodulator and detection blocks at the receiver nano-machine.

100 GHz Parametric CMOS Frequency Doubler

A parametric MOS varactor-based integrated frequency doubler is reported. The circuit is implemented in 130 nm CMOS but uses a conservative 0.35 μm gate length and produces an output between 94 and 108 GHz with a minimum measured conversion loss of 14.5 dB and a maximum output power of -7.5 dBm. Slow-wave transmission line filters are employed to reduce circuit loss and the area required by the chip.