Yoshiaki Inoue

We consider the stationary distributions of the age of information (AoI) and the peak AoI in information update systems. We first derive an invariant relation among the distributions of the AoI, the peak AoI, and the system delay, which holds for a wide class of information update systems. Based on this result, we next obtain several formulas for the stationary distributions of the AoI and the peak AoI in the first-come first-served (FCFS) GI/GI/1 queue, which is a general model of FCFS informat

This paper considers the age of information (AoI) in a stationary information update system with packet deadline and infinite buffer capacity which is modeled as an M/G/1+G queue, where the last symbol represents the probability distribution of deadlines. We first characterize the distribution of the AoI in the general case where service times and deadlines are both generally distributed. We next show that this result is dramatically simplified in the M/M/1+G queue. Finally, we consider the M/M/

Underwater communication is a promising technology to provide ubiquitous network connectivity, where acoustic waves are used as the primary carrier for long-range communication. It has been a challenging research topic to efficiently transmit images with under-water acoustic communication (UAC), due to its inherently narrow bandwidth, strong signal attenuation, time-varying multipath propagation, and low propagation speed. In this paper, we present a new approach to addressing these limitations

Y. Inoue and D. D. Perrin, J. Chem. Soc., 1962, 2600 DOI: 10.1039/JR9620002600

Optical wireless communication is a promising technology for underwater broadband access networks, which are particularly important for high-resolution environmental monitoring applications. This paper focuses on a deep-sea monitoring system, where an underwater optical wireless network is deployed on the seafloor. We model such an optical wireless network as a general queueing network and formulate an optimal relay placement problem, whose objective is to maximize the stability region of the wh

We consider a remote monitoring system where a monitor displays the latest state information obtained from a time-varying information source. Assuming that the information source is represented as a continuous-time Markov chain, we analyze the effect of the age of information (AoI) on the accuracy of the monitoring system. We first obtain the conditional probability of the displayed state, given the actual current state of the information source. We then derive simple lower and upper bounds for

リアルタイム性を重視するモニタリングシステムでは，常に最新の情報をモニタに表示することが肝要であるため，古くなった情報は極めて低い価値しか持たない．すなわち，取得からの時間経過に伴って情報の価値は減衰してゆき，適切な頻度で情報更新がなされない限り，モニタが表示する情報はほとんど無価値になってしまう．従来，このようなシステムに対する代表的な性能評価指標として遅延時間が用いられてきたが，これは情報の鮮度を保つという観点ではあくまで間接的な指標にすぎない．Age of Information (AoI)は，情報の鮮度を直接的に定量化する新しい指標であり，過去数年の間にAoIに関する研究は大きな広がりを見せている．本稿では，AoIの基本概念を解説し，更にその理論的解析法，並びに理論的結果から導かれるAoIの制御に関する基本的な考え方を紹介する．

This paper studies a service system in which arriving customers are provided with information about the delay they will experience. Based on this information, they decide to wait for service or leave the system. Specifically, every customer has a patience threshold, and they balk if the observed delay is above the threshold. The main objective is to estimate the parameters of the customers’ patience-level distribution and the corresponding potential arrival rate, using knowledge of the actual qu

Immediately after the occurrence of a natural disaster, communication infrastructures used in daily life become temporarily unavailable. Under such a situation, intermittently connected mobile ad hoc networks (MANETs) play an important role in providing post-disaster networking. While previous studies on such networks have mainly focused on one-to-one messaging applications, the importance of monitoring applications has become increasingly important in recent years. For monitoring applications,

In this paper, we derive an explicit expression for the probability distribution of the age of information (AoI) in the GI/GI/∞ queue with loss. Two special cases M/GI/∞ and D/GI/∞ are discussed, where the distribution function of the AoI is shown to take a simple closed-form. In addition, a comparison result between the M/GI/∞ and D/GI/∞ queues in terms of the AoI distribution is presented.

Tumours that had grown in syngeneic rats were depleted of macrophages in vitro. A comparison was made with non-depleted tumours of their growth in the feet and spread to the popliteal lymph nodes in untreated, irradiated (500 rads) or carrageenan-treated rats. A non-metastasizing methylcholanthrene-induced fibrosarcoma (D8) grew better in the feet of all three groups after macrophage depletion but metastasized more extensively only in irradiated rats; irradiation increased the growth of non-depl