Enhancing the Quality of Service for Real Time and non-Real Time Application via Internet Network

Services that demanded by users via internet network are classified in two main kinds, Services work in real time such as video and voice in real time and use UDP protocol, and other services that work in non-real time such as web browsing (HTTP) and file transfer (FTP) which use TCP Protocol. In this research, we study and analyze algorithms that enhance the quality of service for various applications. For real time application, we use queues disciplines, which gives high priority for these services and achieves minimum delay. For non-real time application, we study congestion control algorithms, which achieve best performance for reliable transfer process with existing the congestion in the network. We used OPNET 14.5 program for simulating various services via internet network. Simulation results show achieving minimum delay for voice service, and achieving high transmission rate for FTP application with existing of packets loss in the network.

Improving the throughput of reliable transfer in multi hop wireless networks using sliding window and fast retransmit with random linear network coding

Random Linear Network Coding (RLNC) is considered to be one of the promised solutions to achieve the reliability of transmission in multi hop wireless networks, Since it is based on correcting the loss of the packets in the medium through the continuity of transmitting coded packets from each segment until receiving acknowledgment of getting the required number of these packets for decoding. However, because of the nature of wireless medium and multi hops transfer, a loss or delay of the ACK may occur, which causes transmitting extra packets and time delay to the next segments, consequently decreasing the throughput of these networks. In this research, we propose a new transmission mechanism for reliable transfer in multi hops wireless networks through using the concepts of sliding window and fast retransmit with RLNC, for transmitting packets of consequent segments in specific continues flow and fast correcting the loss in these segments. Simulation results show that proposed mechanism decreases the time delay for transmission process and increases the transfer throughput of these networks.