Research Of Transmission Technology For Wireless Network Video Services Based On QUIC

TCP,a widely used transport protocol,has some problems such as head of line blocking,retransmission ambiguity,and connection interruptions owing to the network handover.These issues may cause the online multimedia services suffer low transmission efficiency and high delay,which will undermine the Qo E of users,in wireless scenarios of,e.g.,LTE and WLAN.In order to solve these problems,a new type of multiplex and secure transmission protocol,QUIC,is proposed by Google,which is based on UDP and combines some advantages from several other protocols.QUIC has the advantage of rapid connection establishment,and it not only solves the problems such as head of line blocking,retransmission ambiguity and so on,but also guarantees the continuity of the video services during the network handover.Though having many merits,the communication using QUIC is still greatly affected by the wireless channel quality: Although the transmission performance of QUIC under poor channel quality is better than that of TCP,it is still not up to the expectations and has much room to be optimized.In this thesis,we focus on the QUIC-based video transmission optimization under poor channel quality.At first,we introduce the principle,characteristics,packet and frame formats of QUIC by reviewing QUIC official and related documents.Then the protocol framework and the key mechanism is summarized by perusing the QUIC official source code.Next,based on the characteristics of QUIC protocol,the QUIC transmission enhancement optimization framework in poor wireless coverage scenarios is proposed under the criteria of reducing data transmission and increasing transmission rate.The framework includes some schemes such as reducing the uplink ACK-only,spurious ACK,rearrangement,network resource scheduling and active discard of ACKs of large delay.Lastly,an ACK forwarding enhanced algorithm for the Pacing mechanism is proposed based on active discarding the delayed ACKs.In this algorithm,some of ACKs with long delay,which may reduce the QUIC transmission rate of QUIC and perceived throughput by users,are blocked according to certain criteria.A QUIC simulation system is established to separate and merge the real QUIC data stream with NS3 simulation data stream.With the help simulation system,we can test,verify and analyze the performance of the algorithm.The system consists of three platforms: DASH,NS3 and QUIC.The DASH is used to send service requests and plays the video segment;the QUIC is used to transmit DASH-based flows;and the NS3 is used to provide a simulation network through which the QUIC data is transmitted,such as WLAN and LTE.The simulated algorithm is implemented at the base station of LTE and at the AP of the WLAN in NS3.The performance of the proposed algorithm is tested,analyzed and verified in various scenarios.According to these results,the proposed algorithm can bring a certain gain in most scenarios.Among them,the gain of the algorithm is about 10% in WLAN,and is 20%~35% in LTE.