| 1. |
- Amani, Payam, et al.
(författare)
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Application of Control Theory to a Commercial Mobile Service Support System
- 2012
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Ingår i: International Journal on Advances in Telecommunications. - 1942-2601. ; 5:3&4
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Tidskriftsartikel (refereegranskat)abstract
- The Mobile Service Support system (MSS), which Ericsson AB develops, handles the setup of new subscribers and services into a mobile network. Experience from deployed systems show that traffic monitoring and control of the system will be crucial for handling overload situations that may occur at sudden traffic surges. In this paper we identify and explore some important control challenges for this type of systems. Further, we present analysis and experiments showing some advantages of proposed solutions. First, we develop a load-dependent server model for the system, which is validated in testbed experiments. Further, we propose a control design based on the model, and a method for estimation of response times and arrival rates. The main contribution of this paper is that we show how control theory methods and analysis can be used for commercial telecom systems. Parts of our results have been implemented in commercial products, validating the strength of our work.
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| 2. |
- Amani, Payam, et al.
(författare)
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Multi-step ahead response time prediction for single server queuing systems
- 2011
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Multi-step ahead response time prediction of CPU constrained computing systems is vital for admission control, overload protection and optimization of resource allocation in these systems. CPU constrained computing systems such as web servers can be modeled as single server queuing systems. These systems are stochastic and nonlinear. Thus, a well-designed nonlinear prediction scheme would be able to represent the dynamics of such a system much better than a linear scheme. A nonlinear autoregressive neural network with exogenous inputs based multi-step ahead response time predictor has been developed. The proposed estimator has many promising characteristics that make it a viable candidate for being implemented in admission control products for computing systems. It has a simple structure, is nonlinear, supports multi-step ahead prediction, and works very well under time variant and non-stationary scenarios such as single server queuing systems under time varying mean arrival rate. Performance of the proposed predictor is evaluated through simulation. Simulations show that the proposed predictor is able to predict the response times of single server queuing systems in multi-step ahead with very good precision represented by very small mean absolute and mean squared prediction errors.
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| 3. |
- Amani, Payam, et al.
(författare)
-
NARX-based multi-step ahead response time prediction for database servers
- 2011
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Ingår i: [Host publication title missing]. - 2164-7143. - 9781457716768 ; , s. 813-818
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Konferensbidrag (refereegranskat)abstract
- Advanced telecommunication applications are often based on a multi-tier architecture, with application servers and database servers. With a rapidly increasing development of cloud computing and data centers, characterizations of the dynamics for database servers during changing workloads will be a key factor for analysis and performance improvements in these applications. We propose a multi-step ahead response time predictor for database queries based on a nonlinear autoregressive neural network model with exogenous inputs. The estimator shows many promising characteristics which make it a viable candidate for being implemented in admission control products for database servers. Performance of the proposed predictor is evaluated through experiments on a lab setup with a MySQL-server.
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| 4. |
- Amani, Payam, et al.
(författare)
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Optimal Content Retrieval Latency for Chunk Based Cooperative Content Replication in Delay Tolerant Networks
- 2013
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Konferensbidrag (refereegranskat)abstract
- Modern content distribution networks face an increasing multitude of content generators. In order to reach the minimal content retrieval latency in the content distribution networks, content shall be disseminated towards consumers based on its popularity taken from the content distribution networks. This, Combined with dividing media into chunks (heterogeneous valuation of information) and contact duration of the consumers with the access points in delay tolerant networks led us to a novel system for content management in large scale distributed systems. In order to determine where to replicate content we formulated the problem as an integer programming problem. The cost function of this minimization problem is the accumulated weighted communication delay among the content replication servers and also the main content server. Various practical constraints such as limited total budget for content replication in each service provider, limited storage size and downlink bandwidth of the content replication servers are considered. A centralized solution to the problem is derived which gives the performance bound for any decentralized content replication strategy for the presented scenarios.
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| 5. |
- Amani, Payam
(författare)
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Resource Management in Computing Systems
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Resource management is an essential building block of any modern computer and communication network. In this thesis, the results of our research in the following two tracks are summarized in four papers. The first track includes three papers and covers modeling, prediction and control for multi-tier computing systems. In the first paper, a NARX-based multi-step-ahead response time predictor for single server queuing systems is presented which can be applied to CPU-constrained computing systems. The second paper introduces a NARX-based multi-step-ahead query response time predictor for database servers. Both mentioned predictors can predict the dynamics of response times in the whole operation range particularly in high load scenarios without changes having to be applied to the current protocols and operating systems. In the third paper, queuing theory is used to model the dynamics of a database server. Several heuristics are presented to tune the parameters of the proposed model to the measured data from the database. Furthermore, an admission controller is presented, and its parameters are tuned to control the response time of queries which are sent to the database to stay below a predefined reference value.The second track includes one paper, covering a problem formulation and optimal solution for a content replication problem in Telecom operator's content delivery networks (Telco-CDNs). The problem is formulated in the form of an integer programming problem trying to minimize the communication delay and cost according to several constraints such as limited content replication budget, limited storage size and limited downlink bandwidth of each regional content server. The solution of this problem is a performance bound for any distributed content replication algorithm which addresses the same problem.
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| 6. |
- Amani, Payam, et al.
(författare)
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Towards optimal content replication and request routing in content delivery networks
- 2015
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Ingår i: 2015 IEEE International Conference on Communications (ICC). - 9781467364324 ; , s. 5733-5739
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Konferensbidrag (refereegranskat)abstract
- Cooperative content replication and request routing (C2R3) has emerged as a promising technique to enhance the efficiency of content delivery networks (CDN). Most existing approaches to C2R3 focus on efficient bandwidth usage and assume a hierarchical CDN architecture targeted towards the delivery of specific content types (e.g., video). Therefore, C2R3 problem of covering the broad range of content types with minimum content access delay in a general CDN architecture has attracted little attention. As a potential solution to C2R3, cooperative web caching techniques have become mature. However, these techniques were designed to improve performance indicators tailored to web contents only (i.e., hit rate and byte hit rate). Arguably, improving such indicators does not necessarily lead to optimal access delay especially when the current trend of user-generated contents with diverse popularities and sizes are taken into account. In this paper, we formulate C2R3 as an optimization problem with the objective of minimizing content access delay in a general CDN architecture. A new performance indicator is introduced, and two popularity-based cooperative algorithms are proposed to approach the NP-hard C2R3 problem. Under broad ranges of cache size and popularity distribution parameters, we compare the proposed methods with a cooperative recency-based web caching method. Our simulation results show that the popularity-based methods outperform the recency-based method, and demonstrate close to optimal performance in representative scenarios of real-world situations.
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| 7. |
- Kihl, Maria, et al.
(författare)
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Performance modelling of database servers in a Telecommunication Service Management system
- 2012
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Resource optimization mechanisms, as admission control and traffic management, require accurate performance models that capture the dynamics of the system during high loads. The main objective of this paper is to develop an accurate performance model for database servers in a telecommunication service management system. We investigate the use of a server model with load dependency. Concurrent requests add load to the system and decrease the server capacity. We derive explicit equations for the state probabilities, the average number of jobs in the system and the average response times. Further, we present some heuristics on how to tune the parameters for given measurement data. Also, using testbed experiments, we validate that the model accurately captures the dynamics of a database server with write-heavy workload.
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