LTE (Long Term Evolution) has been standardized in 3GPP (3 rd Generation Partnership Project) to provide higher data throughput as well as lower latency for various IP based services including web browsing, VoIP (Voice over IP), video streaming and so on. In this paper, we evaluate the performance of TCP and UDP when handover is executed in an LTE system. The performance is degraded due to the interference between source and target eNBs (evolved NodeB). Also the handover interruption time negatively affects overall performance. We measure the TCP throughput and the transmission delay of UDP during the handover process by using our indoor and outdoor LTE testbeds. The results show that better TCP throughput performance is obtained by decreasing the A3-offset and the interruption time caused by a handover event is around 80ms.

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Most real-time multimedia services like VoIP (voice over IP), TV conference and real-time gaming require low endto-end delay. In the near future, it is expected that more delay sensitive applications such as cloud computing or telepresence will appear. LTE (long term evolution) is able to provide realtime services in mobile environments. LTE is designed to have an end-to-end delay of less than 5ms. The delay performance in LTE may, however, be degraded by the radio propagation environment or traffic pattern. For example, if the quality of radio signal is poor, more retransmission is required between eNB (evolved NodeB) and UE (user equipment) which degrades the delay performance. If packet size is large, the packets may be segmented which also degrades the delay performance. Thus it is very difficult to predict the delay performance of LTE system prior to its installation. This paper analyzes how the delay performance in the layer 2 (L2) process of LTE is affected depending on the traffic pattern and radio propagation environment. We conduct numerical simulations that consider the L2 processes. The numerical simulation correctly estimates the delay pattern even in a realistic fading environment.