Takahiro Shiroshima

A passive method for estimating overall LTE cell traffic load by using radio quality information of a user terminal

A method of passively estimating the resource block (RB) utilization rate of a serving cell according to radio-quality information measured by a user terminal is proposed. The estimated RB utilization rate can be regarded as the traffic load on the base station. The contribution of this paper is twofold: first, a method for passively estimating a traffic load on a base station via a user terminal without generating any measurement traffic is proposed; second, the effectiveness of the proposed method was validated through experiments on a commercial LTE network.

Predicting touch operations by using hover information in smartphones for data prefetching

This paper presents new methods to predict input operations on smartphones. Frequently occurring poor network conditions such as low signal strength or congestion of the radio link can increase the latency of smartphone operations. Prediction can improve the latency by prefetching the content that is requested by the predicted operation. We developed methods to predict the input operation by using hover detection on the touch screen. Smartphone functions in recent years have included a function to detect the position of a finger several centimeters above the touch screen. The touch position and the type of operation to be performed are predicted by using the detected positions of the finger before the finger touches the screen. We evaluated this method on a smartphone launcher application. The results indicated that our methods were effective for predicting the operation and improving the latency.

Methods for estimating RRC state of mobile terminals in push servers

Push notification services send messages from servers in the cloud to applications on smartphones at any time to notify the applications or users of new or updated information. These services are characterized by frequent background traffic without user operations that affects the energy consumption of the mobile terminal and cellular network load. These factors are related to the RRC (radio resource control) state. If a server takes the RRC state of the mobile terminals into account and controls the timings for sending messages, the energy consumption and cellular network load can be reduced. In this paper, we propose methods for estimating the RRC state in push servers for controlling messaging timings. The evaluation result shows our method achieved an estimation accuracy of 70 % to 99 % depending on the server load for the estimation.

Method for decreasing delay time after bursty loss on handover

We propose a method for decreasing the delay time of an application by switching the transmission control protocol (TCP) connections. People using a mobile network often see that communication stops even though the radio intensity is strong enough for communication because TCP stops sending packets to the application layer when packet loss occurs on the communication path. In addition, packets that have been sent for several seconds before the handover can be lost. TCP resends lost packets over and over again during a handover, and the waiting time until resending becomes long. TCP has to wait until the rest of the waiting time passes to retransmit after a handover. This makes it seem that communication has stopped. In this paper, we propose a method to calculate the time to switch TCP connections for the purpose of comfortable communication. The appropriate time was calculated based on the receiving intervals of packets at the receiver and the time when the handover occurred. The experimental results show that our method reduced the delay time by 95% in the commercial long term evolution network.