Distance estimation schemes for diffusion based molecular communication systems

Molecule concentration is often used as the information carrier to accomplish diffusion-based molecular communications (DMC) among nano-machines. To achieve the optimal functionality, knowing the distance between the transmitter nano-machine (TN) and the receiver nano-machine (RN) is of high importance. In this paper, two distance estimation schemes are proposed based upon the RN-sensed concentration which changes with regards to the time and distance. The RN estimates the distance by means of measuring either the concentration-peak time or received concentration energy. Simulations are performed to compare the accuracy of each scheme and to discover how the diffusion channel and noise may influence the accuracy. Results show that both schemes will provide a beneficial enhancement to molecular communication systems

Bounds on Distance Estimation via Diffusive Molecular Communication

This paper studies distance estimation for diffusive molecular communication. The Cramer-Rao lower bound on the variance of the distance estimation error is derived. The lower bound is derived for a physically unbounded environment with molecule degradation and steady uniform flow. The maximum likelihood distance estimator is derived and its accuracy is shown via simulation to perform very close to the Cramer-Rao lower bound. An existing protocol is shown to be equivalent to the maximum likelihood distance estimator if only one observation is made. Simulation results also show the accuracy of existing protocols with respect to the Cramer-Rao lower bound.Comment: 7 pages, 5 figures, 1 table. Will be presented at the 2014 IEEE Global Communications Conference (GLOBECOM) in Austin, TX, USA, on December 9, 201

Joint Channel Parameter Estimation via Diffusive Molecular Communication

The design and analysis of diffusive molecular communication systems generally requires knowledge of the environment's physical and chemical properties. Furthermore, prospective applications might rely on the timely detection of changes in the local system parameters. This paper studies the local estimation of channel parameters for diffusive molecular communication when a transmitter releases molecules that are observed by a receiver. The Fisher information matrix of the joint parameter estimation problem is derived so that the Cramer-Rao lower bound on the variance of locally unbiased estimation can be found. The joint estimation problem can be reduced to the estimation of any subset of the channel parameters. Maximum likelihood estimation leads to closed-form solutions for some single-parameter estimation problems and can otherwise be determined numerically. Peak-based estimators are proposed for low-complexity estimation of a single unknown parameter.Comment: 14 pages, 2 tables, 8 figures. To appear in IEEE Transactions on Molecular, Biological, and Multi-Scale Communication

Error correction codes for molecular communication systems.

Molecular communications (MC) is a bio-inspired paradigm that aims to utilise molecules to exchange information among nano-machines. Given the tiny devices used in a MC system and the feasibility of MC in biological environments, MC can be applied to many applications ranging from the healthcare to manufacturing fields. In order to better realize these applications in the future, this Ph.D. research is dedicated to the investigation of a more functional, precise and reliable Diffusion-based Molecular Communications (DBMC) system. To achieve this goal, the contributions of this thesis are as follows. Firstly, the point-to-point (PTP) DBMC system with the absorbing receiver model is established and investigated. A study of the accuracy of the analytical channel model is also introduced. Secondly, dependent on different types of the transmitter (TX) and receiver (RX), three different communication scenarios are proposed. Thirdly, to enhance the reliability of the information at RX, the Error Correction Codes (ECCs), as the most prominent technique is employed within the DBMC system to control or correct any errors introduced during the transmission process. Fourthly, due to the limitation of the power budget of the nano-machines, the energy efficiency of the system is also taken into account. Finally, a two-receiver broadcast DBMC system is established with an absorbing interfering receiver (RI) and an absorbing target receiver (RT). By analysing the performance of the communication link between TX and RT (target communication link), the impact of the positions of RI on RT is studied. This study indicates that the application of ECCs does enhance the performance of PTP DBMC systems. In addition, the encoder and decoder design, and the BER performance are shown to be the two primary factors for selecting the most suitable ECC for the application. Finally, considering a two-receiver broadcast DBMC system with absorbing receivers, the existence of RI does affect the performance of the target communication link which is crucial result for the field moving forward