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Zero-error Coding Based ISI Mitigation for Molecular Communication Systems

Abadi, Nastaran | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51135 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Nasiri Kenari, Masoumeh; Mirmohseni, Mahtab
  7. Abstract:
  8. Molecular communication which is inspired by nature has emerged as a promising field in recent years for its potential applications in medicine, environment, tissue engineering, industry and so on. In molecular communication, molecules are the information carriers. One of the mechanisms of movement of molecules that does not require any infrastructure is Diffusion. Diffusion-based molecular communication in which molecules diffuse in the medium in order to reach the receiver, has two major problems: delayed and lost molecules. Due to the randomness of diffusion, molecules are usually received with varied delays, their order of reception is different from the order of transmission and even some of them might divert to other directions or react with other molecules and never make it to the receiver. In order to mitigate these effects and have a reliable communication, a coding scheme is needed. However, due to the different channel model and processing limits in molecular communication, existing codes are not suitable for this purpose. In this thesis, we focus on zero-error coding. The objective of zero-error coding is achieving exact zero decoding error, rather than small decoding error. First established by Shannon, zero-error communication is important for some reasons. Generally, the problem of deriving the maximum possible rate of transmission with zero error, i.e. the zero-error capacity of a channel, is more challenging than deriving the normal capacity and has led to many unsolved problems in the literature. In this thesis, we first concentrate on the problem of delay. Assuming availability of multiple types of molecules in the transmitter side, we consider three models for different methods of transmission of molecules. In each model, we introduce an upper bound of the zero-error capacity and also zero error codes of rates close to the upper bound. Then we examine a channel in which a limited number of molecules might be get delayed by channel. We derive the capacity of such channel for a wide range of parameters. Then we consider lost molecules in addition to delay. In the first case, we suppose a fraction of molecules of each time slot might get lost and all of them might get delayed. We present upper bound of zero-error capacity and zero-error codes for this case. In the second case, we assume a fraction of molecules of each time slot might get lost and a fraction of them (rather than all of them) might get delayed. In this case, we present lower bound of capacity using graph theory techniques
  9. Keywords:
  10. Molecular Communication ; Diffusion ; Delay ; Interference Cancellation ; Zero-Error Communications ; Zerro-error Code

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