Jarmo Harju - Profile on Academia.edu (original) (raw)

Papers by Jarmo Harju

Optimisation of the performance of a rate-based congestion control system by using fuzzy controllers

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.

THE DESIGN OF A FLEXIBLY INTERWORKING DISTRIBUTED MESSAGE-BASED FRAMEWORK

Campus-wide Information Systems, 2007

IPv6 Connectivity, IPv6 over IPv4, IPv6 over VPN, Service Reachability, NAT

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.

Co-operation and Comparison of DiffServ and IntServ: Performance Measurements

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

Based on the Differentiated Services (DiffServ, [1]) model we develop implementation-ready transm... more Based on the Differentiated Services (DiffServ, [1]) model we develop implementation-ready transmission service for video-on-demand (VoD) traffic. In order to satisfy the demands of real-time nature of VoD traffic we propose to use assured forwarding (AF, [4]) per-hop behavior (PHB) group. We provide specific traffic profile parameters which adequately fit to VoD traffic requirements. Using these parameters and AF PHB class we show how to construct a well-defined transmission service that is suitable for VoD traffic delivery. Our service is analytically tractable. It means that using the quality of service (QoS) parameters which should be provided to VoD traffic we can evaluate the required capacity not only within the DiffServ ingress node, but within the interior nodes too. Our transmission service is designed in such way that it is fully characterized by the parameters of DiffServ ingress node, bounds the losses and delay along the path of behavior aggregate and allows us to predict the QoS degradation which can be experienced by both behavior aggregate and single microflows.

Network physical links configuration is one of the most important problems of mobile communicatio... more Network physical links configuration is one of the most important problems of mobile communication network planning because it will determine the long-term performance and service quality of networks. In the 4G Radio Access Network (RAN) a new ring topology of physical links may be applied in contrast to RANs of current wireless systems. In this paper, the problem of the ring configuration of physical links from the viewpoint of minimum 4G RAN construction cost is considered. We formulate this problem as a combinatorial-optimization one and use dynamic programming principle for its solution. Software calculation results demonstrate the capability of our approach to determine the minimum-cost configuration.

Traffic patterns generated by IM services are different from traditional Poisson models used for ... more Traffic patterns generated by IM services are different from traditional Poisson models used for circuit switched voice traffic. As a result, the network parameters can be underestimated. Therefore, the UMTS network planning problem arises. For successful solution of the problem it is necessary to estimate a performance of IM-subsystem elements. In this paper we have analyzed the performance of Gateway GPRS Support Node (GGSN) on a base of FBM/D/1/W queueing system (FBM -Fractional Brownian Motion). Submitted results may be applied for estimation of parameters of UMTS Rel'5 IM-subsystem elements.

The differentiated services (DiffServ, [1]) expedited forwarding (EF, [2]) per-hop behavior (PHB)... more The differentiated services (DiffServ, [1]) expedited forwarding (EF, [2]) per-hop behavior (PHB) is targeted on applications which need strict guarantees of end-to-end delay and should not suffer from packet losses. It makes EF PHB an appropriate choice for lossfree timely delivery of delay and loss intolerant traffic. It is expected that the substantial part of such sort of traffic will be generated by video-on-demand (VoD) services. In order to provide transmission service which is based on EF PHB to VoD traffic, several traffic conditioning functions have to be implemented within the DiffServ ingress nodes. These conditioning functions are based on traffic profiles. In this paper we show how to compute EF PHB traffic profiles for VoD traffic, which are based on simple token bucket mechanism and consider the effect of traffic profile violations. We evaluate both aggregated traffic and per-source quality of service (QoS) degradations caused by traffic profile violations. In order to compute the parameters of EF PHB queue within the DiffServ ingress node we approximate the output stochastic process from the first queuing system by arrival curve. We also consider the VoD traffic treatment within DiffServ interior nodes and show how to compute parameters of EF queues within those nodes.

This paper presents results from performance measurements carried out in a Differentiated Service... more This paper presents results from performance measurements carried out in a Differentiated Services WAN connecting three major cities in Southern Finland. The target of the measurements was to collect precise information about the level of service, experienced by a user transmitting files with FTP in a network that implements service differentiation by using drop precedence levels and separate classes for realtime and non-realtime traffic. Special attention was paid to the behaviour of competing TCP flows produced by users with different service level specifications. Background traffic from ISP's network was injected into our test network in order to create traffic profiles which are typical in a core network. The results show clearly that the SIMA model used for the implementation of the DS mechanisms in the network nodes can provide service differentiation in a useful and fair manner in traffic conditions varying from light load to severe overload.

This paper presents an analytical model of steady state throughput of the Slow-but-Steady variant... more This paper presents an analytical model of steady state throughput of the Slow-but-Steady variant of TCP NewReno as a function of loss event rate, average number of segments lost per loss event, average round trip time, and retransmission timeout value. The presented model is based on the approach proposed by Padhye et al. for TCP Reno throughput modeling and extends it by capturing the effect of fast recovery algorithm of the Slow-but-Steady variant of TCP NewReno on throughput and taking into consideration slow start phase after timeout expiration. Validation by ns-2 simulations shows good agreement and accuracy of the proposed model.

Live video streaming service, which is common nowadays in the Internet, is supposed to be very ch... more Live video streaming service, which is common nowadays in the Internet, is supposed to be very challenging and demanding service in next-generation wireless networks. However, both limited quality of service (QoS) support and unstable quality of the air interface can restrain its wide deployment. In this paper we consider live video streaming over IEEE 802.11b wireless local area network (WLAN), which is claimed to be used as a part of layered infrastructure of next-generation mobile systems to provide coverage in highly populated areas . We performed our experiments under different signal-to-noise ratios (SNRs) and different competing TCP and UDP traffic volumes. The main conclusion of our paper is that despite a common belief live streaming multimedia services are not ready for wide implementation in hot-spot areas where both high traffic volume and relatively weak signal strength (less than 30 dB) may deny the service easily.

IEEE Journal of Quantum Electronics, 2004

Given the current interest in TCP/IP network management research towards Web services, it is impo... more Given the current interest in TCP/IP network management research towards Web services, it is important to recognise how standardisation can be achieved. This paper mainly focuses on the standardisation of operations and not management information. We state that standardisation should be done by standardising the abstract parts of a WSDL document, i.e. the interfaces and the messages. Operations can vary in granularity and parameter transparency, creating four extreme operation signatures, all of which have advantages and disadvantages.

Currently, there is an evolution in wireless communications from GSM Phase 2+ cellular systems to... more Currently, there is an evolution in wireless communications from GSM Phase 2+ cellular systems towards the Fourth Generation (4G) wireless multimedia systems. The 4G systems should offer significantly higher bit rates than 2 Mb/s, also should have higher capacity and lower bit cost then those of the Third Generation (3G) cellular systems and be able to support all types of new and future multimedia services. These requirements will make the 4G Radio Access Network (RAN) different from current RANs .

In this paper we propose the model of single smoothed MPEG traffic source which is based on speci... more In this paper we propose the model of single smoothed MPEG traffic source which is based on special type of D-BMAP arrival process. To our knowledge up to date there was no model of smoothed traffic from the single MPEG source which fits well to both purposes simultaneously: analytical evaluation and simulation studies. Our model is responsible for these tasks. Based on statistical analysis of smoothed MPEG traffic we limit the state space of the modulating Markov chain of the D-BMAP process which models the smoothed MPEG traffic such that it can allow an analytical analysis of the queuing systems. Our model captures both the histogram of relative frequencies and the autocovariance function (ACF) of single smoothed MPEG traffic source well. In addition, it is simple enough and can be easily used in simulation studies even when there is a need to generate the model "on the fly". The simplicity of the model stems from that fact that it employs only four states of the modulating Markov chain and does not require additional expansion of the state space. In addition, the model allows the evaluation of lower bound of approximation error of empirical ACF before the construction of the model. We also present the modeling algorithm which can be implemented in software.

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

To provide a tool for performance evaluation of IP-based delay-and loss-sensitive applications ru... more To provide a tool for performance evaluation of IP-based delay-and loss-sensitive applications running over wireless channels we propose a novel cross-layer wireless channel modeling approach. We firstly develop simple and computationally efficient wireless channel modeling algorithm. For this purpose we adopt the special solution of the inverse eigenvalue problem and show that its complexity significantly decreases when the time-series is covariance stationary two-valued in nature. Our model explicitly takes into account autocorrelation and distributional properties of empirical data. Then, we extend this model to IP layer using the cross-layer mappings. The resulting model is represented by the IP packet error process and reflects memory properties of initial bit error process. We show that our approach allows to get accurate estimators of IP packet error probabilities in presence of FEC at the data-link layer eliminating the need for computationally expensive time-consuming bit level simulations. It also provides a way to choose the required correction capabilities of FEC codes resulting in best possible performance at the data-link and IP layers. q

IMPROVING THE PERFORMANCE OF THE CHANDY-MISRA PARALLEL SIMULATION ALGORITHM IN A DISTRIBUTED WORKSTATION ENVIRONMENT

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

Peer-to-Peer Streaming Technology Survey

... 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 ...