Performance Management and Perceived QoS in LTE networks

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Drozdy Árpád
Department of Broadband Infocommunications and Electromagnetic Theory

The LTE (Long Term Evolution) and LTE Advanced mobile networks use TCP/IP based packet switched communication to transport data. Originally designed for wired networks, the TCP/IP protocol family can not handle connection losses and moderate packet loss well in wireless networks. This causes suboptimal performance and long delays in the data flow. As the demand grows for high speed, short delay internet access in mobile communication, solving these problems becomes a priority.

This paper describes the architecture of the LTE network, focusing mainly on the elements involved in packet data transfer and radio link control, and the TCP/IP protocol family, especially the mechanism of flow and congestion control in TCP. The main point of this paper is to give a clear understanding of the cooperation of these two systems, and analyse the problems that arise when using TCP over the LTE mobile network.

There are a number of already discovered and implemented modifications that address the aforementioned problems. This paper introduces these solutions, and gives an overview of the mechanisms and interactions when using one or more of these modifications.

Lastly, the paper introduces a new unique network modification, called the RCT (Radio Controlled TCP), and describes the function and the inherent behaviour of this solution. Extensive simulation results of the effects of this modification are presented with a specialized LTE network simulator, developed at Nokia Siemens Networks.


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