Mobility: a double-edged sword for HSPA networks

This paper presents an empirical study on the performance of mobile High Speed Packet Access (HSPA, a 3.5G cellular standard) networks in Hong Kong via extensive field tests. Our study, from the viewpoint of end users, covers virtually all possible mobile scenarios in urban areas, including subways, trains, off-shore ferries and city buses. We have confirmed that mobility has largely negative impacts on the performance of HSPA networks, as fast-changing wireless environment causes serious service deterioration or even interruption. Meanwhile our field experiment results have shown unexpected new findings and thereby exposed new features of the mobile HSPA networks, which contradict commonly held views. We surprisingly find out that mobility can improve fairness of bandwidth sharing among users and traffic flows. Also the triggering and final results of handoffs in mobile HSPA networks are unpredictable and often inappropriate, thus calling for fast reacting fallover mechanisms. We have conducted in-depth research to furnish detailed analysis and explanations to what we have observed. We conclude that mobility is a double-edged sword for HSPA networks. To the best of our knowledge, this is the first public report on a large scale empirical study on the performance of commercial mobile HSPA networks

Quality assessment and usage behavior of a mobile voice-over-IP service

Voice-over-IP (VoIP) services offer users a cheap alternative to the traditional mobile operators to make voice calls. Due to the increased capabilities and connectivity of mobile devices, these VoIP services are becoming increasingly popular on the mobile platform. Understanding the user's usage behavior and quality assessment of the VoIP service plays a key role in optimizing the Quality of Experience (QoE) and making the service to succeed or to fail. By analyzing the usage and quality assessments of a commercial VoIP service, this paper identifies device characteristics, context parameters, and user aspects that influence the usage behavior and experience during VoIP calls. Whereas multimedia services are traditionally evaluated by monitoring usage and quality for a limited number of test subjects and during a limited evaluation period, this study analyzes the service usage and quality assessments of more than thousand users over a period of 120 days. This allows to analyze evolutions in the usage behavior and perceived quality over time, which has not been done up to now for a widely-used, mobile, multimedia service. The results show a significant evolution over time of the number of calls, the call duration, and the quality assessment. The time of the call, the used network, and handovers during the call showed to have a significant influence on the users' quality assessments

Structural conditions for business model design in new information and communication services : a case study of multi-play and MVolP in Denmark and Norway

The report analyses the structural conditions for the design of business models regarding new information and communication services. The services examined are mobile VoIP (MVoIP) and multi-play – services that already are on the market, however in their infancy, and which represent different kinds of services in terms of structural conditions market-wise and in regulatory terms. As the two service categories are relatively new on the market, dominating business model designs have not yet settled and the strategic choices of companies are very open. Being on the market, the discussion on the business model design, however, transcends the purely speculative stage. The structural conditions studied are the market conditions including the regulatory conditions. In addition, the different technological solutions are examined, as MVoIP as well as multi-play include different technology solutions for the delivery of services to users. This means that the analysis includes technological as well as market-based and regulatory elements. The aim of the analysis of the structural conditions is two-fold: On the one hand, to deepen the understanding of the structural condition and, on the other hand, to discuss the conditions for different business model design options. The report examines the regulatory policies and market characteristics in MVoIP and multi-play as a basis for a discussion on how these policies and characteristics affect the business model decisions of service providers in the two areas. Using empirical material from Norway and Denmark, the report presents a comparative analysis of the structural conditions and the business model choices made by actors in the market. The basic theoretical framework for the analysis is the Structure-Conduct-Performance (SCP) framework. The strength of this framework is that it stretches all the way from the structural conditions, through the conduct (business models and strategies) of companies seen in connection with these structural conditions, to the actual performance of companies in the market. The focus of the present report is on the structural conditions with a view to the framework that these conditions constitute for the business model design of companies. The empirical basis of the report consists primarily of interviews with representatives from IT and telecom industry organizations, policy makers and regulators in the telecom area in Norway and Denmark

Investigating the QoS of Voice over IP using WiMAX Access Networks in a Campus Network

VoIP is a very rapid evolving communication technology which supports transportation of voice data via IP based networks. In parallel, IEEE 802.16e standard based WiMAX is a new emerging access technology and the first generation of 4G broadband access wireless technology with an enhanced in-built quality of service (QoS) provision with many benefits including cost reduction, high quality as well as other value added network service solutions especially for communications Service Providers with emphasis on real time services. WiMAX promises manifold benefits in terms of optimal network performance across a long distance in contrast to other wireless technologies such as Wi-Fi and 3G cellular technologies. Hence, this research attempts to identify some of the network performance parameters that Service Providers will focus on to develop a VoIP over WiMAX communication tool that will serve as a voice communication broadband replacement technology to old circuit-switch voice communication. This study adopted a simulation-based network performance analysis to investigate the effects of the application of different voice encoder schemes on QoS of VoIP system deployed with IEEE 802.16e standard WiMAX network. Through different network simulation experiments using realistic network scenarios in OPNET environment, this research provided an in-depth network performance comparative analysis of VoIP over WiMAX using performance parameters which indicate QoS such as voice jitter, voice packet ETE delay, packet-sent-packet-received, WiMAX network delay, voice packet delay variation and throughput. The obtained simulation experiment results indicated that choice of suitable codec scheme can affect the QoS of VoIP traffic over WiMAX network. The results also indicated that the choice of suitable voice encoder scheme with a small number of voice frame-size per packet have a significant impact over VoIP traffic performance when deployed with WiMAX access technology. Keywords: WiMAX, QoS, End-to-End delay, Jitter, IEEE 802.16e, PSTN, OPNET, Simulation, Wi-Fi, Code

The Quest for a Killer App for Opportunistic and Delay Tolerant Networks (Invited Paper)

Delay Tolerant Networking (DTN) has attracted a lot of attention from the research community in recent years. Much work have been done regarding network architectures and algorithms for routing and forwarding in such networks. At the same time as many show enthusiasm for this exciting new research area there are also many sceptics, who question the usefulness of research in this area. In the past, we have seen other research areas become over-hyped and later die out as there was no killer app for them that made them useful in real scenarios. Real deployments of DTN systems have so far mostly been limited to a few niche scenarios, where they have been done as proof-of-concept field tests in research projects. In this paper, we embark upon a quest to find out what characterizes a potential killer applications for DTNs. Are there applications and situations where DTNs provide services that could not be achieved otherwise, or have potential to do it in a better way than other techniques? Further, we highlight some of the main challenges that needs to be solved to realize these applications and make DTNs a part of the mainstream network landscape

Towards a GNU/Linux IEEE 802.21 Implementation

Abstract-Multiaccess mobile devices and overlapping wireless network deployments have emerged as a next generation network fixture. To make the most of all available networks, mobile devices should be capable of handing over between heterogeneous networks seamlessly and automatically. At the same time, operators should be able to steer network attachment based on their criteria. Although several cross layer mechanisms have been proposed in recent years, only the Media Independent Handover (MIH) Services framework has advanced in any of the established standardization bodies. This paper presents a blueprint for a GNU/Linux implementation of IEEE 802.21. We review the salient points of the standard, introduce our software implementation architecture, detail information gathering in GNU/Linux, and show how our prototype implementation can be used in practice. In contrast with prior published work, this paper presents a real IEEE 802.21 implementation, not an abstracted or reduced MIH-like framework, tested and empirically evaluated over real heterogeneous networks

Identification of Marketing Capabilities: A study on Indian product based B2B Telecom start-ups

New technology based start-ups play a very important role in developing the economy of a country. In India telecom sector has seen unprecedented growth over the decade and this has led to emergence of several telecom related start-ups. However, product based B2Bstart-ups are still rare and they have to undergo several challenges to stay afloat. Surprisingly not much research work has been undertaken in identifying capabilities among early stage start-ups although the early phase represents a very crucial phase for product based firms and in determines the success or failure for start-ups. Present study explores the inherent marketing capabilities that enable commercialization among such early stage start-ups by adopting a multiple case based inductive methodology with Indian telecom start-ups as our context. We have identified market orientation, positioning and segmentation, selling and after sales services as components of marketing capability of such start-ups. We also identify several idiosyncrasies among telecom start-ups vis-�-vis established firms in the sector. Fina lly we make a case for policy level intervention to promote telecom start-ups in the Indian context.

A study of mobile VoIP performance in wireless broadband networks

Voice service is to date still the killer mobile service and the main source for operator revenue for years to come. Additionally, voice service will evolve from circuit switched technologies towards packet based Voice over IP (VoIP). However, using VoIP over wireless networks different from 3GPP cellular technologies makes it also a disruptive technology in the traditional telecommunication sector. The focus of this dissertation is on determining mobile VoIP performance in different wireless broadband systems with current state of the art networks, as well as the potential disruption to cellular operators when mobile VoIP is deployed over different access networks. The research method is based on an empirical model. The model and experiments are well documented and based on industry standards for voice quality evaluation. The evaluation provides results from both experiments in a controlled laboratory setup as well as from live scenarios. The research scope is first, evaluate each network technology independently; second, investigate vertical handover mobility cases; third, determine other aspects directly affecting end user experience (e.g., call setup delay and battery lifetime). The main contribution of this work is a systematic examination of mobile VoIP performance and end user experience. The research results point out the main challenges for achieving call toll quality, and how derive the required changes and technological performance roadmap for improved VoIP service. That is, investigate how the performance and usability of mobile VoIP can eventually be improved to be a suitable substitute for circuit switched voice. In addition, we evaluate the potential disruption to cellular operators that mobile VoIP brings when deployed over other access networks. This research extends the available knowledge from simulations and provides an insight into actual end user experience, as well as the challenges of using embedded clients in handheld devices. In addition, we find several issues that are not visible or accounted for in simulations in regard to network parameters, required retransmissions and decreased battery lifetime. The conclusion is that although the network performance of several wireless networks is good enough for near toll quality voice in static scenarios, there are still a number of problems which make it currently unfeasible to use as a primary voice service. Moreover, under mobility scenarios performance is degraded. Finally, there are other issues apart from network performance such as energy consumption, hardware limitations and lack of supporting business models (e.g., for WiFi mesh) that further limit the possibility of rolling out mobile VoIP services