The rapid ageing population is posing challenges to many countries all over the world, particularly in the provision of care to the growing number of elderly who are living alone. Allowing the elderly to age-in-place, i.e., live safely and independently in the comfort of their own homes is a model that can potentially address the resource constraint in health and community care faced by many nations. To make this model a reality and provide appropriate and timely care to the elderly, unobtrusive eldercare monitoring systems (EMS) are being deployed in real homes to continuously monitor the activity of the elderly. In this paper, we study the feasibility of detecting behavioral changes using rudimentary binary sensors similar to the ones used by many commercial EMS, as a trigger for early intervention by caregivers. We propose Online Behavioral Change Detection (OBCD), a scheme to automatically detect behavioral changes using online streaming data from binary sensors. OBCD extends existing changepoint detection methods to reduce false positives due to extraneous factors such as faulty sensors, down gateways or backhaul connectivity observed in real deployment environments. The Mann-Whitney test is complemented with a comparison of quartile coefficient of dispersion and a threshold test of the means before and after the change, to filter out changes due to the above-mentioned factors. Our case studies show that OBCD can significantly reduce false positives by 80% or more compared with the Mann-Whitney test without increasing the detection delay, i.e., the time between event occurrence and its detection.
{"title":"Online Detection of Behavioral Change Using Unobtrusive Eldercare Monitoring System","authors":"La Thanh Tam, A. Valera, H. Tan, Cheryl Koh","doi":"10.1145/3016032.3016053","DOIUrl":"https://doi.org/10.1145/3016032.3016053","url":null,"abstract":"The rapid ageing population is posing challenges to many countries all over the world, particularly in the provision of care to the growing number of elderly who are living alone. Allowing the elderly to age-in-place, i.e., live safely and independently in the comfort of their own homes is a model that can potentially address the resource constraint in health and community care faced by many nations. To make this model a reality and provide appropriate and timely care to the elderly, unobtrusive eldercare monitoring systems (EMS) are being deployed in real homes to continuously monitor the activity of the elderly. In this paper, we study the feasibility of detecting behavioral changes using rudimentary binary sensors similar to the ones used by many commercial EMS, as a trigger for early intervention by caregivers. We propose Online Behavioral Change Detection (OBCD), a scheme to automatically detect behavioral changes using online streaming data from binary sensors. OBCD extends existing changepoint detection methods to reduce false positives due to extraneous factors such as faulty sensors, down gateways or backhaul connectivity observed in real deployment environments. The Mann-Whitney test is complemented with a comparison of quartile coefficient of dispersion and a threshold test of the means before and after the change, to filter out changes due to the above-mentioned factors. Our case studies show that OBCD can significantly reduce false positives by 80% or more compared with the Mann-Whitney test without increasing the detection delay, i.e., the time between event occurrence and its detection.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114497929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we consider a cognitive radio network with multiple secondary users (SUs). The SU packets in the system can be divided into two categories: SU1 packets and SU2 packets, where SU1 packets have transmission priority over SU2 packets. Considering the absolute priority of the primary users (PUs), the PU packets have the highest priority in the system to transmit. In order to reduce the transmission interference to the PU packets and the SU1 packets, we propose an adjustable access control scheme for the SU2 packets. A newly arriving SU2 packet can access the system with an access probability related to the total number of packets in the system. A variable factor is also introduced to adjust the access probability dynamically. Based on the working principle of the adjustable access control scheme, we build a discrete-time queueing model with a finite waiting room and an adjustable joining rate. With a steady-state analysis of the queueing model, using a three-dimensional Markov chain, we derive some performance measures of the SU2 packets. Finally, we show the influence of the adjustment factor on different system performance measures by using numerical results.
{"title":"An Adjustable Access Control Scheme in Cognitive Radio Networks with Multiple Secondary Users","authors":"Yuan Zhao, Wuyi Yue","doi":"10.1145/3016032.3016040","DOIUrl":"https://doi.org/10.1145/3016032.3016040","url":null,"abstract":"In this paper, we consider a cognitive radio network with multiple secondary users (SUs). The SU packets in the system can be divided into two categories: SU1 packets and SU2 packets, where SU1 packets have transmission priority over SU2 packets. Considering the absolute priority of the primary users (PUs), the PU packets have the highest priority in the system to transmit. In order to reduce the transmission interference to the PU packets and the SU1 packets, we propose an adjustable access control scheme for the SU2 packets. A newly arriving SU2 packet can access the system with an access probability related to the total number of packets in the system. A variable factor is also introduced to adjust the access probability dynamically. Based on the working principle of the adjustable access control scheme, we build a discrete-time queueing model with a finite waiting room and an adjustable joining rate. With a steady-state analysis of the queueing model, using a three-dimensional Markov chain, we derive some performance measures of the SU2 packets. Finally, we show the influence of the adjustment factor on different system performance measures by using numerical results.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121757081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we present a fluid-flow model to characterize the behavior of the overloaded Session Initiation Protocol (SIP) server with a finite buffer. Our model includes a priority-based request scheduling mechanism (PRSM) which diminishes redundant retransmissions to overcome the overloading of SIP servers. The numerical results closely match with the simulation results, indicating that the proposed models can accurately capture the dynamic behavior of a SIP server with the PRSM. Using the Markov Modulated Poisson Process (MMPP) traffic model, the failure ratio of the PRSM is reduced to zero when the buffer size is higher than 1K while it linearly increases for the conventional SIP. The mean response delay of the PRSM is kept constant around 175 ms while it reaches as high as 179 seconds for the conventional SIP when the buffer size is around 200K.
{"title":"Modeling of Priority-based Request Scheduling Mechanism for Finite Buffer SIP Servers","authors":"Demir Y. Yavas, Ibrahim Hökelek, Bilge Günsel","doi":"10.1145/3016032.3016055","DOIUrl":"https://doi.org/10.1145/3016032.3016055","url":null,"abstract":"In this paper, we present a fluid-flow model to characterize the behavior of the overloaded Session Initiation Protocol (SIP) server with a finite buffer. Our model includes a priority-based request scheduling mechanism (PRSM) which diminishes redundant retransmissions to overcome the overloading of SIP servers. The numerical results closely match with the simulation results, indicating that the proposed models can accurately capture the dynamic behavior of a SIP server with the PRSM. Using the Markov Modulated Poisson Process (MMPP) traffic model, the failure ratio of the PRSM is reduced to zero when the buffer size is higher than 1K while it linearly increases for the conventional SIP. The mean response delay of the PRSM is kept constant around 175 ms while it reaches as high as 179 seconds for the conventional SIP when the buffer size is around 200K.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115878881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With ever-increasing demand for bandwidth, both optical packet switching and optical burst switching are proposed as alternatives to increase the capacity of optical networks in the future. In these packet-based switching techniques, Fiber Delay Lines are used to avoid contention between packets on a single wavelength. The involved scheduling algorithms decide on which Fiber Delay Line each packet is scheduled in order to maximize performance. By selectively delaying packets longer than strictly necessary, we proposed a schedule called void-creation that outperforms existing void-filling algorithms by up to 50 % for a specific setting with fixed packet size. This contribution extends the concept of void-creation to the case of variable size packets. By conditioning the theoretical value of the packet size on the scheduling parameters, we are able to extend the applicability of the void-creating algorithm to a plurality of settings. We therefore developed a numerical procedure that assigns a theoretical value (or, equivalently, negative cost) to each void based on how likely the void will eventually be filled and thus proven useful. Results obtained by Monte Carlo simulation show that our void-values provide a solid and consistent basis to decide upon void creation, and this for a variety of packet size distributions.
{"title":"Optical Switching for Variable Size Packets: Improved Void Filling through Selective Void Creation","authors":"Kurt Van Hautegem, W. Rogiest, H. Bruneel","doi":"10.1145/3016032.3016044","DOIUrl":"https://doi.org/10.1145/3016032.3016044","url":null,"abstract":"With ever-increasing demand for bandwidth, both optical packet switching and optical burst switching are proposed as alternatives to increase the capacity of optical networks in the future. In these packet-based switching techniques, Fiber Delay Lines are used to avoid contention between packets on a single wavelength. The involved scheduling algorithms decide on which Fiber Delay Line each packet is scheduled in order to maximize performance. By selectively delaying packets longer than strictly necessary, we proposed a schedule called void-creation that outperforms existing void-filling algorithms by up to 50 % for a specific setting with fixed packet size. This contribution extends the concept of void-creation to the case of variable size packets. By conditioning the theoretical value of the packet size on the scheduling parameters, we are able to extend the applicability of the void-creating algorithm to a plurality of settings. We therefore developed a numerical procedure that assigns a theoretical value (or, equivalently, negative cost) to each void based on how likely the void will eventually be filled and thus proven useful. Results obtained by Monte Carlo simulation show that our void-values provide a solid and consistent basis to decide upon void creation, and this for a variety of packet size distributions.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131868009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hazim Jarrah, P. Chong, N. Sarkar, Jairo Gutiérrez
This paper considers the problem of system-level fault diagnosis in highly dynamic networks. The existing fault diagnostic models deal mainly with static faults and have limited capabilities to handle dynamic networks. These fault diagnostic models are based on timers that work on a simple timeout mechanism to identify the node status, and often make simplistic assumptions for system implementations. To overcome the above problems, we propose a time-free comparison-based diagnostic model. Unlike the traditional models, the proposed model does not rely on timers and is more suitable for use in dynamic network environments. We also develop a novel comparison-based fault diagnosis protocol for identifying and diagnosing dynamic faults. The performance of the protocol has been analyzed and its correctness has been proved.
{"title":"A Time-Free Comparison-Based System-Level Fault Diagnostic Model for Highly Dynamic Networks","authors":"Hazim Jarrah, P. Chong, N. Sarkar, Jairo Gutiérrez","doi":"10.1145/3016032.3016045","DOIUrl":"https://doi.org/10.1145/3016032.3016045","url":null,"abstract":"This paper considers the problem of system-level fault diagnosis in highly dynamic networks. The existing fault diagnostic models deal mainly with static faults and have limited capabilities to handle dynamic networks. These fault diagnostic models are based on timers that work on a simple timeout mechanism to identify the node status, and often make simplistic assumptions for system implementations. To overcome the above problems, we propose a time-free comparison-based diagnostic model. Unlike the traditional models, the proposed model does not rely on timers and is more suitable for use in dynamic network environments. We also develop a novel comparison-based fault diagnosis protocol for identifying and diagnosing dynamic faults. The performance of the protocol has been analyzed and its correctness has been proved.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129820346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper considers a multiserver retrial queue with setup time which is motivated from application in data centers with the ON-OFF policy, where an idle server is immediately turned off. The ON-OFF policy is designed to save energy consumption of idle servers because an idle server still consumes about 60% of its peak consumption processing jobs. Upon arrival, a job is allocated to one of available off-servers and that server is started up. The server needs some setup time during which the server cannot process a job but consumes energy. An arriving job that sees all the servers occupied (active or setup) joins the orbit and retries to enter an unoccupied server after some random time. We formulate this model using a level-dependent quasi birth- and-death process. Using Foster--Lyapunov criteria, we obtain the stability condition. We also propose a heuristic technique to determine the truncation point for the level-dependent quasi birth-and-death process.
{"title":"Impacts of Retrials on Power-Saving Policy in Data Centers","authors":"Tuan Phung-Duc, K. Kawanishi","doi":"10.1145/3016032.3016047","DOIUrl":"https://doi.org/10.1145/3016032.3016047","url":null,"abstract":"This paper considers a multiserver retrial queue with setup time which is motivated from application in data centers with the ON-OFF policy, where an idle server is immediately turned off. The ON-OFF policy is designed to save energy consumption of idle servers because an idle server still consumes about 60% of its peak consumption processing jobs. Upon arrival, a job is allocated to one of available off-servers and that server is started up. The server needs some setup time during which the server cannot process a job but consumes energy. An arriving job that sees all the servers occupied (active or setup) joins the orbit and retries to enter an unoccupied server after some random time. We formulate this model using a level-dependent quasi birth- and-death process. Using Foster--Lyapunov criteria, we obtain the stability condition. We also propose a heuristic technique to determine the truncation point for the level-dependent quasi birth-and-death process.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130082695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phase-type distributions constitute a very versatile class of distributions. They have been used in a wide range of stochastic modeling applications in areas as diverse as telecommunications, finance, queueing theory, survival analysis, inventory systems. This paper reviews queueing inventory systems (QIS) with phase-type service distributions and discusses their contributions to inventory management. We have classified QIS as features in queueing model such as vacation, service discipline, customer behavior and in inventory model such as review policy, replenishment policy, stock-out assumption. The framework of literature review in this paper clearly provides an overview of the queueing inventory systems and can be used as a starting point for further study.
{"title":"A Survey on the Queueing Inventory Systems with Phase-type Service Distributions","authors":"K. Choi, Bongkyoo Yoon","doi":"10.1145/3016032.3016033","DOIUrl":"https://doi.org/10.1145/3016032.3016033","url":null,"abstract":"Phase-type distributions constitute a very versatile class of distributions. They have been used in a wide range of stochastic modeling applications in areas as diverse as telecommunications, finance, queueing theory, survival analysis, inventory systems. This paper reviews queueing inventory systems (QIS) with phase-type service distributions and discusses their contributions to inventory management. We have classified QIS as features in queueing model such as vacation, service discipline, customer behavior and in inventory model such as review policy, replenishment policy, stock-out assumption. The framework of literature review in this paper clearly provides an overview of the queueing inventory systems and can be used as a starting point for further study.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125456215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The second order measures such as the variance and covariance of the output process in a production system are very useful to design and control the systems in a more effective way. This paper concerns to the two-station system with a buffer of finite capacity. An effective method for evaluating the second moments of the number of outputs and inter-departure times is provided and the effects of the system parameters such as the buffer capacity and the variabilities of the processing time, failure time and repair time to the variability of output processes is investigated. Some applications of the results are also discussed.
{"title":"Variability of output in two-node tandem production line","authors":"Y. Shin, D. Moon","doi":"10.1145/3016032.3016058","DOIUrl":"https://doi.org/10.1145/3016032.3016058","url":null,"abstract":"The second order measures such as the variance and covariance of the output process in a production system are very useful to design and control the systems in a more effective way. This paper concerns to the two-station system with a buffer of finite capacity. An effective method for evaluating the second moments of the number of outputs and inter-departure times is provided and the effects of the system parameters such as the buffer capacity and the variabilities of the processing time, failure time and repair time to the variability of output processes is investigated. Some applications of the results are also discussed.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116609633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper considers an M/M/1 retrial queue where the server not only receives incoming calls but in idle time makes outgoing calls of two types whose durations follow the same exponential distribution. The outgoing calls of type 1 are directed to the customers in orbit while the outgoing calls of type 2 are directed to the customers outside the orbit. Using the generating function approach, we derive explicit expressions and recursive formulas for the stationary joint distribution of the number of customers in the orbit and the server state as well as for the partial factorial moments. A closed form formula for the mean number of customers in the orbit is also obtained.
{"title":"Two-Way Communication M/M/1 Retrial Queue with Server-Orbit Interaction","authors":"V. Dragieva, Tuan Phung-Duc","doi":"10.1145/3016032.3016049","DOIUrl":"https://doi.org/10.1145/3016032.3016049","url":null,"abstract":"This paper considers an M/M/1 retrial queue where the server not only receives incoming calls but in idle time makes outgoing calls of two types whose durations follow the same exponential distribution. The outgoing calls of type 1 are directed to the customers in orbit while the outgoing calls of type 2 are directed to the customers outside the orbit. Using the generating function approach, we derive explicit expressions and recursive formulas for the stationary joint distribution of the number of customers in the orbit and the server state as well as for the partial factorial moments. A closed form formula for the mean number of customers in the orbit is also obtained.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122190733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We address the problem of stabilizing control for complex queueing systems with known parameters but unobservable Markovian random environment. In such systems, the controller needs to assign servers to queues without having full information about the servers' states. A control challenge is to devise a policy that matches servers to queues in a way that takes state estimates into account. Maximally attainable stability regions are non-trivial. To handle these situations, we model the system under given decision rules. The model is using Quasi-Birth-and-Death (QBD) structure to find a matrix analytic expression for the stability bound. We use this formulation to illustrate how the stability region grows as the number of controller belief states increases.
{"title":"QBD Modelling of a finite state controller for queueing systems with unobservable Markovian environments","authors":"A. Asanjarani","doi":"10.1145/3016032.3016041","DOIUrl":"https://doi.org/10.1145/3016032.3016041","url":null,"abstract":"We address the problem of stabilizing control for complex queueing systems with known parameters but unobservable Markovian random environment. In such systems, the controller needs to assign servers to queues without having full information about the servers' states. A control challenge is to devise a policy that matches servers to queues in a way that takes state estimates into account. Maximally attainable stability regions are non-trivial. To handle these situations, we model the system under given decision rules. The model is using Quasi-Birth-and-Death (QBD) structure to find a matrix analytic expression for the stability bound. We use this formulation to illustrate how the stability region grows as the number of controller belief states increases.","PeriodicalId":269685,"journal":{"name":"Proceedings of the 11th International Conference on Queueing Theory and Network Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125444660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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