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HARQ Packet Scheduling Based on RTT Estimation in LTE Networks

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.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0215112-153546
Date15 February 2012
CreatorsLi, Yi-Wei
ContributorsZi-Tsan Chou, Tsung-Chuan Huang, Kao-Shing Hwang, Chung-nan Lee, Tsang-Ling Sheu
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0215112-153546
Rightsunrestricted, Copyright information available at source archive

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