Jarmo Prokkola

Bio: Jarmo Prokkola is an academic researcher from VTT Technical Research Centre of Finland. The author has contributed to research in topics: Quality of service & Network packet. The author has an hindex of 11, co-authored 24 publications receiving 545 citations. Previous affiliations of Jarmo Prokkola include University of Oulu.

Cognitive Radio Trial Environment: First Live Authorized Shared Access-Based Spectrum-Sharing Demonstration

Abstract: Cognitive radio system (CRS) technology can help respond to the growing mobile traffic demand by improving network resource usage and gaining access to new shared spectrum bands. This article presents a cognitive radio trial environment (CORE) consisting of cognitive engines (CEs) to control different radio systems [e.g., long-term evolution (LTE) and wireless open-access research platform (WARP)-based networks]. Load balancing and authorized shared access (ASA) are demonstrated using the trial environment with promising results. The ASA-based spectrum sharing trial is presented for the first time with a real-life mobile network accessing a shared spectrum band under a licensed shared access (LSA) regime. Cognitive decision making brings intelligence to the usage of the radio and network resources and, at best, increases considerably end users? quality of service (QoS) compared to the standard systems, as shown for QoS-based offloading.

Measuring WCDMA and HSDPA Delay Characteristics with QoSMeT

Abstract: Quality of service (QoS) is becoming increasingly important with the rise of multimedia applications (e.g., voice over IP (VoIP), video conferencing, online gaming, and Internet protocol television (IPTV)) in public data networks. These applications demand real-time service, while the networks should still be able to transfer also other traffic reliably (e.g., data, e- mail, WWW). We have developed a measurement tool, which is able to measure one-way QoS performance statistics. The tool enables passive monitoring of the desired application(s) and gives information about the QoS provided by the network. The tool can be used practically over any kind of network structure as long as IP is supported. In this paper, we focus on detailed end-to-end delay characteristics measured in live HSDPA (high speed downlink packet access) enabled 3G network. HSDPA provides clearly better delay performance than the basic WCDMA (wideband code division multiple access). Interestingly, deterministic long time behavior in delay was observed, and also, discrete jitter levels were found. With argumentation, and finally with a trial, we proved that these phenomena originate from the CBR-type (constant bit rate) VoIP source traffic affecting with 3G network timing mechanisms and mutual clock drifts. As a side product, the study also showed that it is advisable to verify the operation of traffic generation tools before using them.

Live field trial of Licensed Shared Access (LSA) concept using LTE network in 2.3 GHz band

Abstract: This paper presents the results from a live field trial of the new Licensed Shared Access (LSA) concept using a TD-LTE network in the 2.3 GHz spectrum band in Finland. In the trial a live LTE network shares the spectrum from incumbent programme making and special events (PMSE) service including cordless cameras without causing harmful interference. The trial implements the new LSA concept and the required new building blocks including LSA Repository for spectrum availability information and LSA Controller for commanding the mobile communication network in the band. The trial uses a real TD-LTE base station, real network management system, and real core network. Incumbent spectrum usage data is collected to the LSA Repository and used by the LSA Controller to retrieve available spectrum bands. LSA Controller uses the network management system to configure the base station according to the spectrum availability information. Incumbent spectrum users' rights are protected by evacuating the LSA band and handing users over from the LTE network to other networks when requested by the incumbent spectrum user. Numerical results are presented to quantify the duration of the LSA band evacuation process. The demonstration shows that the new LSA concept can be implemented with existing network elements and a minimum amount of new components. The first performance results on the LSA band evacuation times indicate that the LSA band can be evacuated and released in good time and the incumbents' rights can be protected.

HSDPA Performance in Live Networks

Abstract: The first HSDPA (high-speed downlink packet access) networks have been recently deployed for operational use. We evaluate and compare live HSDPA operational network performance from the end-user perspective, especially related to voice over IP and Web browsing applications. We compare goodput performance with user datagram protocol (UDP) and transmission control protocol (TCP) in both wideband code division multiple access (WCDMA) and HSDPA. We also address one-way delay measurements to show how up- and downlink asymmetry affects delay and jitter. We found that HSDPA and WCDMA goodput correlate well with the advertised maximum performance values. However, with small payload sizes HSDPA does not bring a substantial improvement over TCP. With UDP the situation is clearly better except with payload sizes commonly used by VoIP. We verify that HSDPA delay is substantially smaller than with WCDMA, as well as the occurrence of delay spikes caused by link level retransmissions. We found that despite 2 ms time division in HSDPA, the main jitter level is at 10 ms. The results can be exploited by operators and equipment manufacturers for service optimisation.

Licensed Shared Access (LSA) trial demonstration using real LTE network

Abstract: This paper presents a demonstration of the new Licensed Shared Access (LSA) concept using a TD-LTE access network in the 2.3 GHz spectrum band in Finland. In the demonstrated trial, the TD-LTE network shares the spectrum of an incumbent spectrum user, who is focused on programme making and special events (PMSE) services. The demonstrator implements the new LSA concept and the required new building blocks including LSA Repository for spectrum protection information and LSA Controller for controlling the mobile communication network in the same band. The trial uses commercial network components like multiband-terminals, TD-L TE base stations, network management system, and core network. Spectrum usage data of incumbents is collected to LSA Repository using two incumbent user tools and is actively updated to LSA Controller for radio network planning to protect the incumbent's activity in the area. LSA Controller uses the information from the base stations and incumbents to protect incumbent spectrum users' rights. This is demonstrated by providing different algorithms, which analyze base stations and sectors that need to be reconfigured to prevent interference from LTE to incumbent (and vice versa). The demonstration shows that the new LSA concept can be implemented with existing network elements and a minimum amount of new components.

What Will 5G Be

Abstract: What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

Modeling and Analyzing Millimeter Wave Cellular Systems

Abstract: We provide a comprehensive overview of mathematical models and analytical techniques for millimeter wave (mmWave) cellular systems. The two fundamental physical differences from conventional sub-6-GHz cellular systems are: 1) vulnerability to blocking and 2) the need for significant directionality at the transmitter and/or receiver, which is achieved through the use of large antenna arrays of small individual elements. We overview and compare models for both of these factors, and present a baseline analytical approach based on stochastic geometry that allows the computation of the statistical distributions of the downlink signal-to-interference-plus-noise ratio (SINR) and also the per link data rate, which depends on the SINR as well as the average load. There are many implications of the models and analysis: 1) mmWave systems are significantly more noise-limited than at sub-6 GHz for most parameter configurations; 2) initial access is much more difficult in mmWave; 3) self-backhauling is more viable than in sub-6-GHz systems, which makes ultra-dense deployments more viable, but this leads to increasingly interference-limited behavior; and 4) in sharp contrast to sub-6-GHz systems cellular operators can mutually benefit by sharing their spectrum licenses despite the uncontrolled interference that results from doing so. We conclude by outlining several important extensions of the baseline model, many of which are promising avenues for future research.

What Will 5G Be

Abstract: What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backwards compatibility. And indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities and unprecedented numbers of antennas. But unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

Enabling the coexistence of LTE and Wi-Fi in unlicensed bands

Abstract: The expansion of wireless broadband access network deployments is resulting in increased scarcity of available radio spectrum. It is very likely that in the near future, cellular technologies and wireless local area networks will need to coexist in the same unlicensed bands. However, the two most prominent technologies, LTE and Wi-Fi, were designed to work in different bands and not to coexist in a shared band. In this article, we discuss the issues that arise from the concurrent operation of LTE and Wi-Fi in the same unlicensed bands from the point of view of radio resource management. We show that Wi-Fi is severely impacted by LTE transmissions; hence, the coexistence of LTE and Wi-Fi needs to be carefully investigated. We discuss some possible coexistence mechanisms and future research directions that may lead to successful joint deployment of LTE and Wi-Fi in the same unlicensed band.

An Overview of Dynamic Spectrum Sharing: Ongoing Initiatives, Challenges, and a Roadmap for Future Research

Abstract: We are in the midst of a major paradigm shift in how we manage radio spectrum. This paradigm shift is necessitated by the growth of wireless services of all types and the demand pressure imposed on limited spectrum resources under legacy management regimes. The shift is feasible because of advances in radio and networking technologies that make it possible to share spectrum dynamically in all possible dimensions—i.e., across frequencies, time, location, users, uses, and networks. Realizing the full potential of this shift to Dynamic Spectrum Sharing will require the co-evolution of wireless technologies, markets, and regulatory policies; a process which is occurring on a global scale. This paper provides a current overview of major technological and regulatory reforms that are leading the way toward a global paradigm shift to more flexible, dynamic, market-based ways to manage and share radio spectrum resources. We focus on current efforts to implement database-driven approaches for managing the shared co-existence of users with heterogeneous access and interference protection rights, and discuss open research challenges.