Jarmo Harju | Tampere University (original) (raw)
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Papers by Jarmo Harju
This article describes a congestion control protocol, based on the use of fuzzy controllers, for ... more This article describes a congestion control protocol, based on the use of fuzzy controllers, for efficient utilisation of the capacity of the network. The basic control mechanism uses rate-based control, closely resembling the one specified by the ATM Forum for the Available Bit Rate (ABR) service category. Fuzzy logic is utilised in the network elements to enhance the required control
As the mobility and the number of affordable, powerful, and highly portable devices becoming netw... more As the mobility and the number of affordable, powerful, and highly portable devices becoming networked increases, so will the amount of networked services offered, managed and discovered. In this paper, we discuss the need and use of service discovery mechanisms in future fixed and mobile networks. In particular, we choose to focus on future enterprise networks that we anticipate would need to support both fixed and wireless terminals with IPv6 and Mobile IPv6 access. We describe service discovery mechanisms using the Service Location Protocol (SLP) in IPv6, and propose extensions to the protocol for utilisation by visiting mobile devices using Mobile IPv6, that will allow service discovery to be performed without breaking compatibility to standard SLP. The extensions introduce 2 new Agents for mobility detection and overcoming limitations of multicast usage by Mobile Nodes in foreign networks. Finally we describe our SLP implementation for IPv6.
Campus-wide Information Systems, 2007
We propose simple and computationally efficient wireless channel modeling algorithm. For this pur... more We propose simple and computationally efficient wireless channel modeling algorithm. For this purpose we adopt the special case of the algorithm initially proposed in [1] and show that its complexity significantly decreases when the time-series is covariance stationary binary in nature. We show that for such time-series the solution of the inverse eigenvalue problem returns unique transition probability matrix of the modulating Markov chain that is capable to match statistical properties of empirical frame error processes. Our model explicitly takes into account autocorrelational and distributional properties of empirical data. We validate our model against empirical frame error traces of IEEE 802.11b wireless access technology operating in DCF mode over spread spectrum at 2Mbps and 5.5 Mbps bit rates. We also made available the C code of the model as well as pre-compiled binaries for Linux and Windows operating systems at http://www.cs.tut.fi/~moltchan.
IETF has developed two architectures for the Internet, Integrated Services (IntServ) and Differen... more IETF has developed two architectures for the Internet, Integrated Services (IntServ) and Differentiated Services (DiffServ), which should enable QoS based handling of data flows in IP networks. This paper presents a number of measurements which were carried out in order to determine some performance differences between these QoS mechanisms, as well as some characteristics about their joint use. The results show that in some cases the flow aggregation model, i.e. DiffServ, can provide the same or even better QoS than the reservation based model, i.e. IntServ
IEEE Journal of Quantum Electronics, 2004
An intention to adopt IP protocol for future mobile communication and subsequent extension of Int... more An intention to adopt IP protocol for future mobile communication and subsequent extension of Internet services to the air interface calls for advanced performance modeling approaches. To provide a tool for accurate performance evaluation of IP-based applications running over the wireless channels we propose a novel cross-layer wireless channel modeling approach. We extend the small-scale propagation model representing the received signal strength to IP layer using the cross-layer mappings. Proposed model is represented by the IP packet error process and retains memory properties of initial signal strength process. Contrarily to those approaches developed to date, our model requires less restrictive assumptions regarding behavior of the small-scale propagation model at layers above physical. We compare results obtained using our model with those, published to date, and show that our approach allows to get more accurate estimators of IP packet error probabilities.
Computer Communications, 2006
In this paper the conservative Chandy-Misra parallel simulation algorithm is discussed. The basic... more In this paper the conservative Chandy-Misra parallel simulation algorithm is discussed. The basic a lgorithm is improved by using null message cancellation, simulation loop optimization and multicasting techniques. The a lgorithms are used for the simulation of a GSM mobile network application in a distributed workstation environment, Diworse. In the simulation results, special attention is paid to the e xecution
... These values were measured by disconnecting from the access network and measuring how long th... more ... These values were measured by disconnecting from the access network and measuring how long the stream ... jitter in the access net-work do not have much effect to the user experience, be-cause the ... Table 3 shows how the quality of the selected applica-tions was seen by our ...
This article describes a congestion control protocol, based on the use of fuzzy controllers, for ... more This article describes a congestion control protocol, based on the use of fuzzy controllers, for efficient utilisation of the capacity of the network. The basic control mechanism uses rate-based control, closely resembling the one specified by the ATM Forum for the Available Bit Rate (ABR) service category. Fuzzy logic is utilised in the network elements to enhance the required control
As the mobility and the number of affordable, powerful, and highly portable devices becoming netw... more As the mobility and the number of affordable, powerful, and highly portable devices becoming networked increases, so will the amount of networked services offered, managed and discovered. In this paper, we discuss the need and use of service discovery mechanisms in future fixed and mobile networks. In particular, we choose to focus on future enterprise networks that we anticipate would need to support both fixed and wireless terminals with IPv6 and Mobile IPv6 access. We describe service discovery mechanisms using the Service Location Protocol (SLP) in IPv6, and propose extensions to the protocol for utilisation by visiting mobile devices using Mobile IPv6, that will allow service discovery to be performed without breaking compatibility to standard SLP. The extensions introduce 2 new Agents for mobility detection and overcoming limitations of multicast usage by Mobile Nodes in foreign networks. Finally we describe our SLP implementation for IPv6.
Campus-wide Information Systems, 2007
We propose simple and computationally efficient wireless channel modeling algorithm. For this pur... more We propose simple and computationally efficient wireless channel modeling algorithm. For this purpose we adopt the special case of the algorithm initially proposed in [1] and show that its complexity significantly decreases when the time-series is covariance stationary binary in nature. We show that for such time-series the solution of the inverse eigenvalue problem returns unique transition probability matrix of the modulating Markov chain that is capable to match statistical properties of empirical frame error processes. Our model explicitly takes into account autocorrelational and distributional properties of empirical data. We validate our model against empirical frame error traces of IEEE 802.11b wireless access technology operating in DCF mode over spread spectrum at 2Mbps and 5.5 Mbps bit rates. We also made available the C code of the model as well as pre-compiled binaries for Linux and Windows operating systems at http://www.cs.tut.fi/~moltchan.
IETF has developed two architectures for the Internet, Integrated Services (IntServ) and Differen... more IETF has developed two architectures for the Internet, Integrated Services (IntServ) and Differentiated Services (DiffServ), which should enable QoS based handling of data flows in IP networks. This paper presents a number of measurements which were carried out in order to determine some performance differences between these QoS mechanisms, as well as some characteristics about their joint use. The results show that in some cases the flow aggregation model, i.e. DiffServ, can provide the same or even better QoS than the reservation based model, i.e. IntServ
IEEE Journal of Quantum Electronics, 2004
An intention to adopt IP protocol for future mobile communication and subsequent extension of Int... more An intention to adopt IP protocol for future mobile communication and subsequent extension of Internet services to the air interface calls for advanced performance modeling approaches. To provide a tool for accurate performance evaluation of IP-based applications running over the wireless channels we propose a novel cross-layer wireless channel modeling approach. We extend the small-scale propagation model representing the received signal strength to IP layer using the cross-layer mappings. Proposed model is represented by the IP packet error process and retains memory properties of initial signal strength process. Contrarily to those approaches developed to date, our model requires less restrictive assumptions regarding behavior of the small-scale propagation model at layers above physical. We compare results obtained using our model with those, published to date, and show that our approach allows to get more accurate estimators of IP packet error probabilities.
Computer Communications, 2006
In this paper the conservative Chandy-Misra parallel simulation algorithm is discussed. The basic... more In this paper the conservative Chandy-Misra parallel simulation algorithm is discussed. The basic a lgorithm is improved by using null message cancellation, simulation loop optimization and multicasting techniques. The a lgorithms are used for the simulation of a GSM mobile network application in a distributed workstation environment, Diworse. In the simulation results, special attention is paid to the e xecution
... These values were measured by disconnecting from the access network and measuring how long th... more ... These values were measured by disconnecting from the access network and measuring how long the stream ... jitter in the access net-work do not have much effect to the user experience, be-cause the ... Table 3 shows how the quality of the selected applica-tions was seen by our ...