General Additive Increase and Multiplicative Decrease (General AIMD or GAIMD) congestion control generalizes the standard TCP congestion control mechanism. In this paper, we present GAIMD-SS, an enhanced model for predicting the long-term steady-state mean throughput of the GAIMD congestion control, towards more accurate results than previous GAIMD model. We develop a three-state Markov chain for analyzing the behaviors of the GAIMD, and enhance previous works by taking into account the slow start phase and receiver's maximum window limitation. Our experiment and simulation results show that the GAIMD-SS model predicts the sending rate of GAIMD congestion control more accurately than the previous works in a wider range of packet loss rate.
Supporting end-to-end QoS of media streaming applications over wireless Internet has received tremendous interest recently. In this paper we propose a new architecture for transmitting real-time multimedia streams over Bluetooth wireless Internet integrated with Differentiated Services (DiffServ) mechanism. IP support over Bluetooth is discussed in details to take advantage of the DiffServ framework. In our proposed architecture, the Bluetooth wireless users are connected to the Bluetooth LAN Access Point to acquire the capability of Internet access. Different media streams are classified at edge routers of the DiffServ core network, mapped to different priorities and delivered according to the dynamically negotiated Service Level Agreement (SLA). QoS monitoring agents deployed in network nodes and endsystems can monitor network QoS conditions and provide reports to the concerned nodes. Implementation details of the prototype of the proposed architecture are given in this paper. Specially, the Bluetooth communication is implemented as a virtual network card that supports IP protocol in order to provide consistent access to the DiffServ Internet. Experimental results show that enhanced end-to-end QoS can be achieved based on our architecture.
Headers of IP packets are growing and the bandwidth required for transmitting headers is increasing. To overcome such limitations, current protocol mechanisms need to be improved. This paper addresses this important issue - Header Compression Scheme. Our compression scheme is presented and compared with some other previous methods. We can show how to reduce the size ofUDP/IP headers down to several limited bytes to efficiently use the bandwidth. In order to efficiently transfer data over lossy links, the congestion control module in our scheme is also discussed. With the information from congestion control, the size of the window mentioned above can be changed according to the congestion situation. When severe congestion is probed, the decrease of window size can obviously increase the stability of the system. This is another key error avoidance step in our system. Finally, we analyze our system under windows 2000 and Ns2 framework. The experimental data are given to testify the validity and performance of our scheme.