Symbol Synchronization for Diffusion-Based Molecular Communications

作     者：Jamali, Vahid Ahmadzadeh, Arman Schober, Robert 

作者机构：Friedrich Alexander Univ Inst Digital Commun D-91058 Erlangen Germany 

出 版 物：《IEEE TRANSACTIONS ON NANOBIOSCIENCE》 (IEEE纳米生物科学汇刊)

年 卷 期：2017年第16卷第8期

页      面：873-887页

核心收录：

学科分类：0710[理学-生物学] 0808[工学-电气工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：German Science Foundations [SCHO 831/7-1] Friedrich-Alexander-University Erlangen-Nuremberg under the Emerging Fields Initiative 

主　　题：Diffusive molecular communications symbol synchronization insertion and deletion errors 

摘      要：Symbol synchronization refers to the estimation of the start of a symbol interval and is needed for reliable detection. In this paper, we develop several symbol synchronization schemes for molecular communication (MC) systems where we consider some practical challenges, which have not been addressed in the literature yet. In particular, we take into account that in MC systems, the transmitter may not be equipped with an internal clock and may not be able to emit molecules with a fixed release frequency. Such restrictions hold for practical nanotransmitters, e.g., modified cells, where the lengths of the symbol intervals may vary due to the inherent randomness in the availability of food and energy for molecule generation, the process for molecule production, and the release process. To address this issue, we develop two synchronization-detection frameworks which both employ two types of molecule. In the first framework, one type of molecule is used for symbol synchronization and the other one is used for data detection, whereas in the second framework, both types of molecule are used for joint symbol synchronization and data detection. For both frameworks, we first derive the optimal maximum likelihood (ML) symbol synchronization schemes as performance upper bounds. Since ML synchronization entails high complexity, for each framework, we also propose three low-complexity suboptimal schemes, namely a linear filter-based scheme, a peak observation-based scheme, and a threshold-trigger scheme, which are suitable for MC systems with limited computational capabilities. Furthermore, we study the relative complexity and the constraints associated with the proposed schemes and the impact of the insertion and deletion errors that arise due to imperfect synchronization. Our simulation results reveal the effectiveness of the proposed synchronization schemes and suggest that the end-to-end performance of MC systems significantly depends on the accuracy of the symbol synchroniza