Title page for etd-0215112-153546


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URN etd-0215112-153546
Author Yi-Wei Li
Author's Email Address No Public.
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Department Communications Engineering
Year 2011
Semester 1
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title HARQ Packet Scheduling Based on RTT Estimation in LTE Networks
Date of Defense 2012-01-12
Page Count 61
Keyword
  • HARQ
  • LTE
  • packet retransmission
  • non-real-time
  • real-time
  • RTT
  • Abstract In an LTE (Long-Term Evolution) network, HARQ (Hybrid Automatic Repeat reQuest) is used to reduce the error probability of retransmitted packets. However, HARQ cannot guarantee delay constraints for real-time traffic when RBs (Resource Blocks) are allocated improperly. To avoid the retransmitted real-time packets exceeding their delay constraints, we propose an HARQ scheduling scheme based on RTT (Round-Trip-Time) estimation. In this scheme, traffic are classified into real-time and non-real-time queues in which real-time queue are further classified into four sub-queues according to their retransmission times; i.e., the first transmission queue,
    the first retransmission queue, the second retransmission queue, and the third retransmission queue. For the four real-time queues, we estimate RTT and compute the number of RBs required satisfying the delay constraints. To prevent from starvation of non-real-time traffic, after allocating the RBs for real-time traffic, the remaining RBs are allocated for non-real-time traffic according to their MBR
    (Minimum Bit Rate). To analyze the proposed scheduling scheme, we build a mathematical model to derive the successful probability of retransmitted packets and the expected value of packet retransmission times. Finally, we compute average packet delay, average packet loss rate, and the throughput for both real-time and none-real-time traffic by varying packet error probability and the delay constraints of real-time traffic.
    Advisory Committee
  • Chung-nan Lee - chair
  • Zi-Tsan Chou - co-chair
  • Kao-Shing Hwang - co-chair
  • Tsung-Chuan Huang - co-chair
  • Tsang-Ling Sheu - advisor
  • Files
  • etd-0215112-153546.pdf
  • indicate access worldwide
    Date of Submission 2012-02-15

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