Sumiko Miyata

Characteristic analysis of an access-point selection for user throughput and system optimization based on user cooperative moving

We propose an optimal access-point (AP) selection algorithm for maximizing system throughput while preserving newly arrived-user throughput. In our algorithm, newly arrived users cooperate with a WLAN system they are trying to use, i.e., they are willing to move toward an appropriate AP. We discuss the effectiveness of our proposed AP selection algorithm by using numerical analysis. We also clarify and analyze the characteristics of system throughput.

Accepting more general telephone calls in emergency situations by limiting general call holding time under trunk reservation control

We investigated the effect of limiting the holding time of general telephone calls on their acceptance rate during an emergency situation. Simulation using a queuing system model of a telephone exchange showed that limiting the holding time of general calls increased the number of accepted general calls even when their acceptance was threshold-controlled while still enabling the required number of emergency calls to be accepted. An investigation of the relationship between the traffic intensity of accepted general calls and the general call-blocking rate showed that an upper limit on the traffic intensity can be set by using threshold control. Limiting the holding time enables more general callers to share the acceptable traffic intensity, which reduces the general call-blocking rate. Calculation of the call-blocking rate for various numbers of lines in a telephone exchange showed that the effect of a general call holding time limitation on the general call-blocking rate is equivalent to that obtained by adding a certain number of lines.

Optimal threshold characteristics of call admission control by considering cooperative behavior of users (loss model)

Call admission control (CAC) is an important technology for maintaining Quality of Service (QoS) in Software-Defined Networking (SDN). The most popular type of CACs is trunk reservation (TR) control, and many TR control methods had been proposed for improving evaluation values such as call blocking probability or the resource utilization rate. In general, some users under these TR control methods may behave cooperatively. However, conventional TR methods do not take into account a users cooperative behavior when they begin to communicate. In this paper, we propose a novel TR-type CAC method by considering the cooperative behavior of some users. This proposed method is presented using the loss model of queueing theory for the call-level analysis of a single link. We also analyze the characteristics of the optimal control parameter.

Exact mean packet delay for delayed report messages multipoint control protocol in EPON

The infrastructure to develop the next generation optical access network is the Ethernet passive optical network (EPON). Interleaved polling with adaptive cycle time (IPACT) is a common polling method of an EPON. However, the mean waiting time of packets (= the mean packet delay) with IPACT is large depending on the arriving time of the packets. In this paper, a novel media access method for IPACT is proposed in order to minimize the mean packet delay. The mean packet delay with the proposed method is also derived as the exact solution. This solution is based on the non-trivial simplification of the previous work on the analytical solution for general IPACT. We confirm a close match between simulation and our theoretical results and show the effectiveness of our method.

Why are so many lines still reserved for emergency telephone calls in emergency situations

We propose a threshold relaxation and holding time limitation for general telephone calls under trunk reservation control in emergency situations. This TR-HTL method aims to accept more general calls while required emergency calls are still accepted. Computer simulation with a queueing system model of a telephone exchange showed that the threshold relaxation increased the number of accepted general calls while still enabling the required number of emergency calls to be accepted. Comparison between two strategies to set the holding time limit of general calls showed that the value of the limit and the call-blocking rate are in a strong trade-off relationship when the limit is short. An investigation of the relationships between the threshold relaxation rate and the call-blocking rate showed that reserving just 5% of the estimated traffic intensity of emergency calls enabled the required number of emergency calls to be accepted, increasing the number of accepted general calls. Moreover, we showed that much fewer reserved lines are needed for guaranteeing emergency calls.

Exact Mean Packet Delay Analysis for Long-Reach Passive Optical Networks

The long reach passive optical network (LR-PON) is a promising scheme for access networks that cover large areas. For designing an access network, an exact solution of the network performance (e.g., mean packet delay) is useful. Since long propagation delay causes unused time slots (idle time), and its effect on performance degradation is difficult to analyze, existing analysis of the LR-PON is done only for the no-idle time situation with modified optical line terminal (OLT) and each optical network unit (ONU). In this paper, we propose an exact solution of the mean packet delay for LR-PON with idle time. Our analytical solution is derived by a non-trivial extension of the existing work for the short range PON. We confirm a good match between the mean packet delay derived by the simulation and our analytical solution.

Threshold configuration of emergency trunk reservation considering traffic intensity for accepting more general telephone calls

We propose a threshold configuration and holding time limitation for general telephone calls under trunk reservation control in emergency situations. Our proposed method aims to accept more general calls while required emergency calls are still accepted. With our method, the threshold is configured in consideration of the ratio of traffic intensities which are estimated in advance. Computer simulation with a queueing system model of a telephone exchange showed that the general call-blocking rate was much lower than that without threshold relaxation or trunk reservation, while the emergency call-blocking rate was reduced to almost zero unless the sum of estimated traffic intensity was nearly equal to the number of lines. Moreover, we confirmed that the threshold was appropriately configured by using the proposed method, from the comparison between the result of the proposed method and that obtained by using the fixed value of a threshold.

An access-point selection algorithm for user QoS and system optimization based on user cooperative moving

We propose an optimal access-point (AP) selection algorithm for maximizing system throughput while preserving newly arrived-user throughput. In our algorithm, newly arrived users cooperate with a wireless area network system they are trying to use, i.e., they are willing to move toward an appropriate AP. We use our algorithm to determine the optimal AP. Moreover, we discuss the effectiveness of our proposed algorithm by using numerical analysis.

A basic study of the flow admission control of mixed loss and delay system based on equality of heterogeneous traffic

We have proposed a novel Call Admission Control (CAC) to maximize total user satisfaction in a heterogeneous traffic network and showed the effectiveness of our CAC by using optimal-threshold from numerical analysis[1]. In our previous CAC, when a new broadband flow arrived and if total accommodated bandwidth was more than or equal to the threshold, the arriving new broadband flow was rejected. In actual networks, however, users may accept to wait for a certain period until the broadband flow, such as video, begins to play. In this paper, when total accommodated bandwidth was more than or equal to the threshold, arriving broadband flows wait instead being rejected. As a result, we can greatly improve total user satisfaction.

A Basic Study of Heterogeneous Flow Admission Control Based on Equality of Flow Classes

We propose a novel flow admission control that minimizes the total call-blocking rate by treating heterogeneous flows equally. We focused on the static-state bandwidth load, which refers to how much bandwidth is used statically by a smaller class of flow than a newly arriving flow. In this paper, we analyze the characteristics of different types of loads, explain the development of a call-blocking curve to minimize the total call-blocking rate, and demonstrate good performance by this call-blocking curve.