In this paper, we first investigate the characteristics of movie contents over the Internet. As in the previous studies, we found the lognormal-distribution well fits the distribution of file size for the whole set of general movie contents. When we specifically focus on the subset that consists of movie trailers, however, it shows different distribution from the lognormal-distribution. Our analysis shows it is similar to an exponential-distribution. We here assume that movie trailers are one of the relevant contents for Contents Delivery Networks (CDN) or Peer-to-Peer (P2P) file exchange communities. We further studies the relationship between playing duration and file size for the movie trailers and we did not find any linear correlation among them. We next consider bandwidth requirements to retrieve movie trailer contents. Our objective is to make it possible for user to view the contents in real-time. Many previous studies investigate bandwidth requirement based only on the file size distribution. In this paper, we analyze the traffic design criteria for CDN or P2P by taking into account both of the results for the file size distribution and the relationship between playing duration and file size for movie trailers. Simulation studies reveal the impact for the bandwidth requirement.

In this paper we propose a cross-layer retransmission control for TCP communication over a wireless link. With our proposed control, a retransmission delay for lost packet is reduced, packet losses in the wireless link are eliminated and all packets are delivered in the correct order. No change is required to TCP itself or to the sender. Our proposed method is implemented in a queue between the media access control (MAC) layer and logical link layer in a base station, and is designed to assist local retransmission control in the MAC layer. Computer simulations show that our proposed method can maximally use the bandwidth of the wireless link under high bit error rates conditions with conventional TCP control. The fairness problem of TCP communication between connections with different bit error rates in a wireless link is also improved, and MAC level fairness is also controllable.

This paper presents and analyzes the following queueing model for congestion control. In an M/M (Poisson arrival/exponential service time) type model with finite waiting room, the input rate into the system is gradually controlled by comparing the number of calls in the system with two threshold values. If an arriving call finds the system to be full, the call is lost and the regulation grade is tightened by one level, i.e. the input rate slows down. If a leaving call finds the number of calls in the system to be lower than the lower threshold, input regulation grade is loosened by one level, i.e. the input rate speeds up. The method is called hysteresis" control. An efficient calculation procedure is devised for steady state probabilities. Some numerical results are shown. Here, in the example, mean service time grows linearly with the number of calls in the system. The graphs show that the input regulation method is effective for preventing such a system from falling into a congested state. This analysis can easily be applied to an input regulation model with finite sources.

This paper surveys and discusses traffic control in ATM networks. Traffic control can be classified into path level control, call level control and cell level control. The effectiveness and the remaining problems are clarified for each level of control. The emphasis is on research activities in this field in Japan.

This paper reports on studies of queueing systems having finite waiting buffers and many processors with two input streams, one of which is given preference over the other by buffer reservation. The arrival patterns for the two streams are different. One stream is described by a renewal process and the other is Poissonian. The former is called a GI call, and the latter a Poisson call. The buffer reservation model in this paper is an analogy from a trunk reservation model for telephone network. Two models are considered, giving priority to either Poisson calls or GI calls. The buffer reservation models have some practical applications to packet switched network and integrated communication systems such as voice and data systems. The models are analyzed using piecewise Markov process theory and transient solutions for an M/M/S/K queueing model. In addition, some numerical results are shown for loss probability and mean waiting time, as well as throughput rate. Traffic characteristics are consequently clarified.

While social media is now used by many people and plays a role in distributing information, it has recently created an unexpected problem: the actual shrinkage of information sources. This is mainly due to the ease of connecting people with similar opinions and the recommendation system. Biased information distribution promotes polarization that divides people into multiple groups with opposing views. Also, people may receive only the seemingly positive information that they prefer, or may trigger them into holding onto their opinions more strongly when they encounter opposing views. This, combined with the characteristics of social media, is accelerating the polarization of opinions and eventually social division. In this paper, we propose a model of opinion formation on social media to simulate polarization. While based on the idea that opinion neutrality is only relative, this model provides new techniques for dealing with polarization.

Telecommunication networks have evolved from telephony networks to the Internet, and they sustainably support the development of a secured, safe, and comfortable society. The so-called “switching technology” including the evolved “network system technology” is one of the main infrastructure technologies used for realizing information communication services. On the occasion of completion of 100 years since the establishment of the IEICE, we summarize the history of network system technologies and present their future direction for the next generation. We mainly focus on a series of technologies that evolved through the discussions of the IEICE technical committees on switching engineering, launched 50 years ago, switching systems engineering, and network systems in action.

The system is composed of multiple processors and finite buffers. Two Poisson streams arrive at the system, one of which is controlled to enter the system by a two-level threshold regulation method with continuous monitoring. An efficient numerical procedure for analysis is presented.