关键词: 传输控制协议, 长期演进, 超时重传计时器, 切换

Abstract: A dynamic Retransmission Timeout (RTO) algorithm: DRTO (Dynamic RTO) for solving the TCP packets out-of-order caused by LTE network handover was proposed. The essence of DRTO was to use the TCP packet sequence number to distinguish the old and the new packets. Hence the multiplicative factor calculated in the past traditional RTO could be replaced by the difference of the serial number. The algorithm did not need to modify the handover mechanism, which can solve the packet out-of-order between the first part of packets (the packets transferred from source eNB to target eNB) which was transferred before handover process and the second part of the packets (the packets sent by server) which was transferred after handover process. Finally, the DRTO algorithm was compared with the traditional RTO algorithm on NS-2 simulation platform. The simulation results show the DRTO algorithm is better than the traditional RTO algorithm in terms of throughput, the number of retransmission packets and latency.

Key words: Transmission Control Protocol (TCP), Long Term Evolution (LTE), Retransmission Timeout (RTO), handover