This paper discusses the stability of TCP. More precisely, the stationary behavior of the congestion window process is analyzed based on the measured real Internet traffic (bulk data transfer, FTP of large files). Appropriate algorithm approximating the actual congestion window is presented, and statistical methods to analyze the data are discussed in detail: change-point detection, distribution testing and parameter estimation. It has been shown that the distribution of the congestion window process during stable periods has a bell-like shape and can be approximated by a normal distribution. A number of interesting observations during the study are depicted and explained. Finally, possibilities for building reliable and robust models for the TCP protocol in the future, are discussed.

In this paper, the performance of MSK signal transmission over a mobile radio channel with small time dispersion is analyzed. In contrast to existing investigations, we made no restrictive assumptions about the impulse response of the channel or the sampling time and derive analytical expressions for the error floor and the optimum sampling instant. We found that the error probability depends not only on the delay spread, but also on the squared mean delays of echoes that are advanced or delayed with respect to the sampling point and on the power balance between them. Furthermore, we show that in the general case, the optimum sampling instant is not identical to the mean delay. Comparison of our results with Monte Carlo simulations show very good agreement.