F. Laakso, “Studies on High Speed Uplink Packet Access Performance Enhancements“, Ph.D. Thesis, ISBN 978-951-39-5984-5, University of Jyväskylä, 2014.
The purpose of this thesis is to address variety of performance related aspects in terms of Third Generation (3G) mobile networks.
From a practical perspective, wireless network sets a very demanding environment for different services due to, e.g., limited User Equipment (UE) battery power, transmission delays, packet loss and varying network performance.
This thesis addresses the aforementioned challenges by evaluating different transmit diversity options, battery saving opportunities, Interference Coordination (IC), Range Extension (RE) and Dual-Carrier (DC) in Uplink (UL).
The studies are conducted with the help of time driven quasi-static system level simulator where, e.g., fading, propagation and Radio Resource Management (RRM) functionality is explicitly taken into account.
J. Turkka, “Aspects of Knowledge Mining on Minimizing Drive Tests in Self-Organizing Cellular Networks“, Ph.D. Thesis, ISBN 978-952-15-3401-0, Tampere University of Tech., 2014.
This thesis studies the Minimization of Drive Tests in self-organizing cellular networks from three different aspects.
The first aspect is network operations, and particularly the network fault management process, as the traditional drive tests are often conducted for troubleshooting purposes. The second aspect is network functionality, and particularly the technical details about the specified measurement and signaling procedures in different network elements that are needed for automating the collection of the field measurement data.
The third aspect concerns the analysis of the measurement databases that is a process used for increasing the degree of automation and self-awareness in the networks, and particularly the mathematical means for autonomously finding meaningful patterns of knowledge from huge amounts of data.
Although the abovementioned technical areas have been widely discussed in previous literature, it has been done separately and only a few papers discuss how for example, knowledge mining is employed for processing field measurement data in a way that minimizes the drive tests in self-organizing LTE networks.
Z. Chang, T. Ristaniemi, and Z. Niu, “Radio Resource Allocation for Collaborative OFDMA Relay Network with Imperfect Channel State Information“, IEEE Transaction on Wireless Communications, 2014.
This paper addresses the resource allocation problem in collaborative relay-assisted OFDMA networks. Recent works on the subject usually ignored either the selection of relays, asymmetry of the source-to-relay and relay-to-destination links or the imperfections of channel state information.
In this article we take into account all these together and our focus is two-fold. Firstly, we consider the problem of asymmetric radio resource allocation, where the objective is to maximize the system throughput of the source-to-destination link under various constraints. In particular, we consider optimization of the set of collaborative relays and link asymmetries together with subcarrier and power allocation. Using a dual approach, we solve each sub-problem in an asymptotically optimal and alternating manner.
Secondly, we pay attention to the effects of imperfections in the channel-state information needed in resource allocation decisions. We derive theoretical expressions for the solutions and illustrate them through simulations.
The results validate clearly the additional performance gains through an asymmetric cooperative scheme compared to the other recently proposed resource allocation schemes.
J. Puttonen, S. Rantanen, F. Laakso, J. Kurjenniemi, K. Aho and G. Acar, “Satellite Model for Network Simulator 3“, Proc. of the 7th International ICST Conference on Simulation Tools and Techniques (Simutools 2014), Lisbon, Portugal , March 17-19, 2014.
Digital Video Broadcasting (DVB) organisation has published a bluebook for the 2nd generation of satellite return link specification, DVB-RCS2. Also, the evolution of DVB-S2, currently called DVB-SX, is in standardization process.
Simulations have increased importance in standardization support as well as in internal product development due to the ability to provide faster feedback on technological solutions without the need for early-stage testbed and real systems development.
However, there is a need for modular open-source satellite system simulator which would adopt the latest DVB satellite standards. Current simulators owned by satellite vendors, operators and research organizations may be proprietary, generally tailored for special purposes and/or may be based on commercial licenses.
In this article we present the building blocks and architecture of satellite model developed on top of a widely used open source system/packet level simulator Network Simulator 3 (NS-3). The satellite extensions are based on DVB-S2 and DVB-RCS2 specifications for forward and return links, respectively. Simulator module is developed to be highly modular and flexible to be able to match the future R&D needs of satellite system vendors, operators, research organizations, as well as the scientific community.
J. Puttonen, S. Rantanen, F. Laakso, J. Kurjenniemi, K. Aho and G. Acar, “Satellite Module for Network Simulator 3“, Proc. of the Workshop on NS-3 (WNS3), Atlanta, USA, May 7, 2014.
J. Puttonen, S. Rantanen, F. Laakso, J. Kurjenniemi, K. Aho and G. Acar, “A Packet Level Simulator for Future Satellite Communications Research“, Proc. of the 32nd AIAA International Communications Satellite Systems Conference, San Diego, USA, August 4-7, 2014.
High Throughput Satellites (HTS) provide many times the throughput of the conventional satellites for the same amount of allocated orbital spectrum. Increased capacity can be provided due to multiple spot beams and frequency re-use whereas conventional satellites use single broad beam or a few beams. These kind of multi-beam systems can also use more advanced Radio Resource Management (RRM) algorithms to control interference levels between beams.
System level simulations have increased importance in system design as well as in standardization support due to the ability to provide faster feedback on technological solutions without the need for early-stage test-bed and real systems development. However, there is a need for modular open-source satellite system simulator which would adopt the latest Digital Video Broadcasting (DVB) satellite standards.
The DVB organisation has published a bluebook for the 2nd generation of satellite return link specification, DVB-RCS2. Also, the evolution of DVB-S2, called DVB-S2x, has been standardized by DVB organization in March 2014. Current simulators owned by satellite vendors, operators and research organizations may be proprietary, generally tailored for special purposes and/or may be based on commercial licenses.
In this paper we present an overview of a satellite model developed on top of an open-source system/packet level simulator Network Simulator 3 (NS-3) and we are concentrating on the packet acquisition modelling including Signal-to-Noise-and-Interference (SINR) calculation and interference modelling. The simulator module is developed to be highly modular and flexible to be able to match the future R&D needs of satellite system vendors, operators, research organizations, as well as scientific community.
V. Hytönen, B. Herman, J. Puttonen, S. Rantanen, J. Kurjenniemi and O. Smeyers, “Satellite Network Emulation with Network Simulator 3“, Proc. of the Ka Band Utilization Conference, Salerno, Italy, October 1-3, 2014.
This paper discusses how the integration of the Satellite Network Simulator 3 (SNS3) with a real-life test-bed environment can be executed and the challenges with the emulation.
Network Simulator 3 (NS3) allows user to perform real-time emulation by providing methods for the simulator to interact with the test-bed environment. Benefits of the emulation are that the user can experiment the performance and behavior of real higher layer protocols, traffic and hardware with simulated transmission media or network.
An integral part of the study is the ETSI DVB-S2/DVB-RCS2 satellite extension module for NS3. The SNS3 models a multi-spot beam geostationary (GEO) satellite network with transparent (bent-pipe) payload and supports a high number of features, allowing a detailed simulation of satellite communication, which makes it an interesting platform for a test-bed integration. A typical satellite network scenario may contain even thousands of end users distributed over a large geographical area.
Emulation of such extensive cases, where real traffic and protocols can be employed provides to researchers and developers important knowledge with regards to capability and reliability of the system that would be almost impossible to verify otherwise.
J. Turkka, U. Mondal and T. Ristaniemi, “An Efficient Grid-based RF Fingerprint Positioning Algorithm for User Location Estimation in Heterogeneous Small Cell Networks“, Proc. of the International Conference on Localization and GNSS, Helsinki, Finland, June 24-26, 2014.
This paper proposes a novel technique to enhance the performance of grid-based Radio Frequency (RF) fingerprint position estimation framework.
The first enhancement is an introduction of two overlapping grids of training signatures. As the second enhancement, the location of the testing signature is estimated to be a weighted geometric center of a set of nearest grid units whereas in a traditional grid-based RF fingerprinting only the center point of the nearest grid unit is used for determining the user location. By using the weighting-based location estimation, the accuracy of the location estimation can be improved.
The performance evaluation of the enhanced RF fingerprinting algorithm was conducted by analyzing the positioning accuracy of the RF fingerprint signatures obtained from a dynamic system simulation in a heterogeneous LTE small cell environment.
The performance evaluation indicates that if the interpolation is based on two nearest grid units, then a maximum of 18.8% improvement in positioning accuracy can be achieved over the conventional approach.
Z. Chang, T. Ristaniemi and Z. Niu, “Energy Efficient Grouping and Scheduling For Content Sharing based Collaborative Mobile Cloud“, Proc. of the IEEE International Conference on Communications (ICC’14), Sydney, Australia, June, 2014.
In order to fully exploit the high speed broadband multimedia services, prolonging the battery life of user equipment is critical, especially for the current smartphones.
In this work, we investigate the problem of designing a content sharing collaborative mobile cloud (CMC) via user cooperation to reduce the energy consumption at terminal side. Given a group of users interested in downloading the same content from an operator, a grouping and scheduling based algorithm is proposed in order to select the proper data receiver in each scheduling time.
The objective of the presented algorithm is to obtain energy efficiency as well as user fairness among the members of CMC. The proposed scheme can take both base station and terminal aspects into consideration and it is shown that the significant energy saving performance can be achieved without scarifying and drowning the battery of any terminal.
F. Chernogorov, S. Chernov, D. Petrov and T. Ristaniemi, “Data Mining Framework for Random Access Failure Detection in LTE Networks“, Proc. of the IEEE Symposium on Personal, Indoor and Mobile Radio Communications 2014, Washington DC, September 2-5, 2014.
The sleeping cell problem is a particular type of cell degradation. There are various software and hardware reasons that might cause such kind of cell outage.
In this study, a cell becomes sleeping because of Random Access Channel (RACH) failure. This kind of network problem can appear due to misconfiguration, excessive load or software/firmware problem at the Base Station (BS). In practice such failure might cause network performance degradation, which is hardly traceable by an operator.
In this paper we present a data mining based framework for the detection of problematic cells. In its core is the analysis of event sequences reported by a User Equipment (UE) to a serving BS. The choice of N in N-gram feature selection algorithm is considered, because of its significant impact on computational efficiency. Moreover, qualitative and heuristic performance metrics have been developed to assess the performance of the proposed detection algorithm.
Sleeping cell detection framework is verified by means of a dynamic LTE (Long-Term Evolution) system simulator, using Minimization of Drive Testing (MDT) functionality. It is shown that sleeping cell can be determined with very high reliability even using 1-gram algorithm.
J. Puttonen and F. Chernogorov, “The Effect of Discontinuous Reception and RRC Release Timer Parameterization on Mobility“, Proc. of the Vehicular Technology Conference (VTC Spring), 2014 IEEE 79th, Seoul, South Korea, May, 2014.
In 3rd Generation Partnership Project (3GPP), enhancements of Diverse Data Applications (eDDA) work item has targeted at improving always-on connectivity for smartphones, identifying and specifying mechanisms at the Radio Access Network (RAN) level to enhance the ability of 3GPP Long Term Evolution (LTE) to handle diverse traffic profiles.
The key aspects are the Radio Resource Control (RRC) release timer for User Equipment (UE) state control between connected and idle modes, and Discontinuous Reception (DRX) targeted for minimizing the UE power consumption in connected state. There exist important tradeoffs between UE power consumption, Quality-of-Service and RAN/core network signalling load. What’s more, these tradeoffs may be dependent on the UE mobility/velocity.
In this article we study the effect of DRX and RRC release timer parameterization on UE mobility performance in heterogeneous networks. These results can be applied to parameter optimization of DRX and RRC release.
P. Eskelinen, W. Kifle, B. Wegmann, I. Viering and A. Klein, “Super-Cell From Inner Sectors of Active Antenna System (AAS) – Vertical Sectorization“, Proc. of the IEEE ICC 2014 – Wireless Communications Symposium, Sydney, Australia, June 10-14, 2014.
Active Antenna System (AAS) is an advanced antenna technology that features the ability of advanced beam-forming techniques to provide a great flexibility in cellular network deployment which enables improvements in network capacity and coverage.
Conventionally, network dimensioning is done based on busy hour traffic leading to cost-intensive over-dimensioning for most of the time via deploying additional macro and small cells. In AAS, however, varying traffic concentrations can be flexibly handled by dynamic cell densification, e.g. by splitting a sector into smaller “sub-sectors”.
Vertical sectorization is a well-known approach where a conventional sector is split vertically in to two, inner and outer sectors, resulting in 3×2 sectors per site for AAS-based tri-sectorized site.
In this paper work, an alternative vertical sectorization deployment configuration is presented where the inner sectors build a so called super-cell resulting from transmitting the same cell information in all inner sectors.
Investigation results show that the super-cell configuration can mitigate unwanted back and side lobe effects in close proximity of the site and, therefore, provides a significant gain for users in this coverage area.
B. Herman, N. Baldo, M. Miozzo, M. Requena and J. Ferragut, “Extensions to LTE Mobility Functions for ns-3“, Proc. of the Workshop on NS-3 (WNS3), Atlanta, USA, May 7, 2014.
ns-3 is an open-source network simulator with support for simulating the 3GPP LTE cellular network.
This paper presents three extensions to the LTE module of ns-3, enhancing its capability of simulating scenarios with more sophisticated user mobility requirements.
The first extension implements additional features in the UE measurements function. The second extension delivers additional handover algorithms and a modular framework for ns-3 users to incorporate their own handover algorithms. At last, the third extension enables automatic network attachment using the initial cell selection procedure.
The modelling of these extensions refers to 3GPP standard specifications. The resulting models have been validated using the ns-3 testing framework.
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