Impact of RTT on TCP Performance Over (E)GPRS Mobile Networks

J. Torreblanca, G. Gómez, and R. Cuny (Spain)


Transport Control Protocol, (E)GPRS Cellular Networks, Round Trip Time, Cell Reselection, Mobility, Delay Spike.


In this article, the Round Trip Time (RTT) behaviour in (E)GPRS networks and its impact on Transport Control Protocol (TCP) performance is addressed. Special emphasis is given to the probability of TCP retransmissions due to different cellular events, such as cell reselections or load conditions. By means of simulations, it has been proved that cell reselections with long outage times (higher than 1 second) and also variances in the radio resource sharing imply a high probability of TCP retransmissions, and therefore, a degradation of the service performance. Advanced TCP features, like Selective Acknowledgement (SACK) and TimeStamp improve TCP performance by minimizing the probability of TCP retransmissions.

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