Research On Remote Screen Sharing On Wireless Conference Cooperation And Projecting System

Reducing network traffic comes to the first consideration while sharing screen on a bandwidth-limited Ad Hoc network. As any transmission is broadcasted to all other nodes in Ad Hoc networks, traditional TCP-based remote screen sharing to multi-clients always wastes much bandwidth. IP multicast is the most effective means to reduce the occupied bandwidth. Packets may be lost while using IP multicast, but all existing methods of reliable multicast have the same aim to insure all group members against loss of any packet in WAN, except for some characteristic implementation on network topology, the feedback of packet loss, retransmission, and so on. There has not been any proper mechanism for the remote screen sharing on a broadcast-type network.A novel IP multicast-based transmitting and controlling mechanism is presented to reduce the bandwidth consumption. In view of the IP multicast transmission unreliability and the partial screen update, a protocol providing limited quality assurance is proposed. On one hand, the correlation among IP packets is reduced to decrease the packet loss influence, by dividing update region into small rectangles and compressing and transmitting each in one packet independently. On the other hand, the different life time of data for different regions is automatically adjusted to reduce redundant retransmissions, by combining lost regions with the update.Some necessary steps for the transmission mechanism are still described. Firstly, state the traffic control strategy and packet length according to the BER (bit error rate). Secondly, propose an effective algorithm to combine some regions together. Thirdly, design buffer strategy to paint a whole update region together which is divided into multi update packets. And finally, allocate multicast addresses with the characteristic of the multicast source and some pseudo-random number to avoid data interruption between different instances.Both modeling and experimental data show, that the screen sharing mechanism presented in this paper can adjust the lifetime of data for different regions adaptively and avoid redundant retransmission of dead data, and with some other steps working together, this mechanism can obviously save bandwidth, while providing clear display on clients.