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Energy Harvesting in Wireless Communication Networks

Moradian, Masoumeh | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48886 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ashtiani, Farid
  7. Abstract:
  8. In this dissertation, we focus on two types of EH cooperative networks. In the first type, the source and relay nodes access a shared channel according to a random access protocol. Also, they harvest energy from non-RF environmental resources. The relay node has data and energy buffers to store the packets of the source and the harvested energy, respectively. Our main goal is to find the optimal relaying protocol at the relay node. In this regard, the first type of the EH cooperative networks are investigated in two different scenarios. In the first one, the MAC channels of the nodes are independent of the applied policy at the relay node, and thus the throughput of the network is fixed. However, in the second scenario, the MAC channel of the source node is dependent on the decisions at the relay node. This dependency results in a tradeoff between degrading the MAC channel of the source due to probable collisions resulted by relay transmissions and improving the PHY channel of the source due to relaying. The optimal static and dynamic policies are designed in order to minimize the average transmission delay of the source packets in both scenarios and maximize the throughput in the second scenario, respectively. These policies indicate how the source packets are accepted in the relay node and are prioritized over the relay packets for transmission. In the static policy, the decisions are made irrespective of the data and energy buffer states. We use a quasi-birth-death process in order to analyze the performance of a static policy. However in the dynamic policy, the decisions change with the status of the energy and data buffers. Thus, we derive the optimal dynamic policy through modeling the problem as a constrained Markov decision process. We show in the second scenario that maximum throughput is achieved in non-cooperation or fullcooperation policies. Also, we derive the necessary and sufficient condition under which the non-cooperation is delay-optimal. In the second type of the EH cooperative networks, the relay and source nodes access the channel in a scheduled manner. Also the relay node harvests energy from ambient RF waves including the source transmissions. It is equipped with a single antenna, consequently is not able to decode the data and harvest the energy at the same time. Thus, a time-switching protocol is applied at the relay node to select either the data decoding (DD) or the EH mode. The static and dynamic switching policies are derived in order to balance the backlogs of the data and energy buffers. We show that the throughput-optimal static and dynamic policies are achieved at the boundary of stability and the throughput-optimal and delay-optimal dynamic policies have some threshold-based structures
  9. Keywords:
  10. Random Access ; Energy Harvesting ; Delay ; Optimization ; Cooperative Network ; Cooperation Communication ; Markov Decision Making ; Network Throughput ; Quasi-Birth-Death Process

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