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Cooperative Relaying in a Multiuser Random Access Network with Energy Harvesting Nodes

Mortazavi, Mohammad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51137 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ashtiani, Farid; Mirmohseni, Mahtab
  7. Abstract:
  8. Energy crisis has always been a crucial issue faced by the development of wireless communication techniques. As a more energy-efficient network architecture, green communications and networks (GCNs) have recently attracted significant attention from academia and industry. In order to enable the technical and economical GCNs, several emerging techniques have been proposed including energy-efficient and energy harvesting techniques. Although these emerging techniques have drawn considerable attention and have been studied recently, there are still many open theoretical and practical problems to be addressed. Energy harvesting (EH) is a key technology to achieve the objectives of GCNs. This technology is more useful for some types of communication network scenarios, e.g., sensor networks. Sometimes sensors should work in conditions that their batteries cannot be replaced easily. In such cases, exploiting sensors with EH capability is of crucial importance. In a network of EH nodes, efficient use of energy on the one hand and exploiting the extra energy supply on the other hand is very important. Cooperative relaying can be an effective technique in this respect. In this thesis, we consider a network composed of two EH sensors and one EH relay. Each sensor updates its status sensing information (packet) when the previous sensing packet has been sent. All nodes transmit based on a predefined slotted Aloha protocol. The main challenge we study is to find how the relay node must share its energy between two sensors. We derive the optimal relaying policy in order to maximize the total status update rate of two sensors such that the update rate of each sensor is better than its rate without relay. To this end, we map the problem onto an exact potential game. Considering a fairness constraint, we obtain the maximum total update rate while the update rates of two sensors are not very far from each other. Finally, we present numerical results to show how much the cooperative relaying policies in our scenario can improve the update rates. Following the same trend, we also derive the optimal relaying policy in order to minimize the average packet transmission delay of two sensors such that the average packet transmission delay of each sensor is less than its average packet transmission delay without relay
  9. Keywords:
  10. Energy Harvesting ; Sensor Network ; Random Access ; Cooperative Relaying ; Green Communication ; Average Packet Transmission Delay ; Status Update Rate