R. Mullner

Nokia Siemens Networks, Esbo, Southern Finland Province, Finland

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Publications (15)0 Total impact

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    ABSTRACT: Uplink power control in UTRAN Long Term Evolution consists of an open-loop scheme handled by the User Equipment and closed-loop power corrections determined and signaled by the network. In this study the difference in performance between pure open-loop and combined open and closed-loop power control has been analyzed and the different behavior of fractional vs. full path-loss compensation has been evaluated. A comprehensive system level simulation model has been used with a facility to trace a particular test user during its motion from eNodeB towards the cell border and back to its initial position. This study demonstrates the effect of distance path-loss of a test user on several physical layer performance metrics including throughput, resource allocation as well as modulation and coding scheme utilization. Simulation results in a fully loaded network show high throughput for open-loop fractional power control for the user located in the vicinity of the serving eNodeB, however, steep performance degradation has been observed when the user is moving towards the cell edge. The user throughput at the cell border can be increased by the closed-loop component. The benefit of closed-loop power control is the higher homogeneity in terms of throughput across the entire network area and the ability to automatically stabilize the network performance under different conditions like cell load and traffic distribution.
    Communications, 2009. ICC '09. IEEE International Conference on; 07/2009
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    ABSTRACT: This paper provides a detailed performance comparison between closed loop (CL) and open loop (OL) MIMO schemes for the upcoming OFDM based mobile broadband radio access technology 3GPP UTRA LTE. Based on system level simulation results, key performance indicators like cell throughput, user throughput and MIMO utilization have been evaluated for different system load conditions assuming 2�?2 MIMO in a regular hexagonal cell deployment and in a real network scenario. A realistic dynamic MIMO switch between diversity and spatial multiplexing has been assumed, which is based on configurable CQI as well as rank filtering and decision thresholds. 3GPP compliant measurement granularity as well as appropriate measurement errors have been applied to both CQI and closed loop PMI reports. Besides dynamic MIMO switching, both MIMO 2�?2 diversity and MIMO 2�?2 spatial multiplexing scenarios have been investigated for the downlink direction highlighting the differences of the various MIMO transmission modes and their impacts on spectral efficiency and radio performance. It has been shown that ideal closed loop MIMO provides a 2 dB theoretical performance gain over open loop MIMO. Assuming practical limitations such as available granularity, delay and realistic PMI measurement errors, however, this gain significantly decreases below roughly 1 dB. Nevertheless MIMO proves to be an appropriate method to boost user throughput especially at low to medium system load up to a factor of 2. Moreover the dynamic MIMO switch proves to be very robust against variations of parameter settings.
    01/2009;
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    ABSTRACT: In mobile networks a most economic utilization of the channels on the air interface by means of intelligent radio resource management is desired since these resources are the most valuable ones. Half-rate speech codecs introduced in GERAN networks for capacity increase involve quality degradation compared to full-rate codecs especially in error-prone radio channel conditions. To provide best possible speech quality the available resources in the network should be utilized as extensive as possible. In addition flexible mechanisms are required to provide additional capacity whenever needed for obtaining the optimum trade-off between quality expectations and capacity requirements. In this study two different load dependent half-rate allocation algorithms for speech services have been proposed. The performance differences have been evaluated thoroughly by system level simulations and compared in terms of system performance. Applied quality criteria are frame erasure rate, bad speech quality probability, codec mode distribution, speech quality indicator and call drop rate. The results show significant differences in channel utilization, speech quality and achieved network capacity.
    Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
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    ABSTRACT: The introduction of the upcoming GERAN evolution feature package in current GSM/EDGE deployments offers operators significant boost in network capacity and mobile data users UMTS/HSPA like high speed packet data services along with competitive latency. Intelligent radio resource management supports novel dual-carrier capable mobile stations by dynamic configuration of GPRS/EDGE packet data channels (PDCHs) on multiple non-BCCH carriers. In addition the currently standardized EDGE2 level B (EDGE2-B) concept provides enhanced PDCH data rates up to 118.4 kbps per timeslot. In this paper system level simulation results for the end-to-end performance of GERAN over TCP/IP are presented assuming conventional 4 timeslots up to future potential 14 timeslots capable EDGE and EDGE2-B mobiles showing up to 800 / 1600 kbps peak data rates. FTP-application throughput has been investigated with respect to both download file size and important TCP settings such as e.g. receiver window size. The GERAN dual-carrier performance has been evaluated for EDGE and EDGE2-B both under ideal radio conditions and in regular hexagonal cellular deployments depending on system load, exemplifying FTP 500 kbyte download with 8 timeslots capable mobiles. At medium system load EDGE2-B compared to EDGE reveals about 100% capacity gain and more than 60% gain in mean user throughput.
    Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
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    ABSTRACT: Dual antenna interference cancellation (DAIC) recently introduced by 3 GPP standardization as a natural evolution step of its predecessor single antenna interference cancellation (SAIC) to further improve the spectral efficiency in GERAN networks is based on the enhancement of the SAIC inherent downlink advanced receiver performance (DARP) feature by receive diversity. In this study focus has been set on a proper and efficient modelling of DAIC in terms of link-to-system level simulator interface (LSLI). A novel memory saving approach for the design of LSLI suggests a lower and upper bound for the dominant interference ratio (DIR) metric to be used in system level simulations. Using the new approach system level simulations have been performed showing roughly three to four-fold capacity gain w.r.t. today's conventional AMR networks and a gain of factor two compared to deployments with 100% SAIC penetration.
    Personal, Indoor and Mobile Radio Communications, 2007. PIMRC 2007. IEEE 18th International Symposium on; 10/2007
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    ABSTRACT: As customer demand for wireless data services increases the bandwidth requirements for new applications are rapidly growing Half-rate speech codecs have been introduced in GERAN networks to save operator's spectrum shared by circuit switched voice and packet switched data services. The released physical resources by allocating voice calls on half-rate channels can be efficiently utilized to significantly increase the data rate of packet switched services. Since by nature the speech quality on half-rate channels is inferior to that on full-rate channels a dynamic half-rate assignment strategy has been introduced triggering half-rate allocation by taking into account both the radio conditions of the voice call and the cell traffic load. Provided that the radio conditions are sufficient voice calls are temporarily allocated on half-rate channels during periods of high traffic load to ensure high quality of service level for packet data applications. In this study the trade-off between speech quality and data capacity has been analyzed by means of system level simulations. Exploiting half-rate allocation at the expense of certain speech quality degradation results in a substantial reduction of the number of blocked data calls as well as in a significant increase in the packet data throughput. Yet almost the same performance for packet data services is achieved by pure and dynamic half-rate allocation, the latter strategy provides significant speech quality gain for 50% of the subscribers.
    Mobile and Wireless Communications Summit, 2007. 16th IST; 08/2007
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    ABSTRACT: Audio bandwidth extension in AMR-WB to twice of that used in AMR-NB provides essential subjective speech quality improvements, while the link level performance in GERAN networks for codec modes of comparable source bit rate is similar. This study analyzes the effect of improved audio perception as well as the impact of channel errors and call drops on the network performance. Profound system level simulations for relaxed 4times3 and 3times3 frequency re-use as well as tight 1times1 reuse have been performed In 4times3 and 3times3 re-use networks, whose capacity is limited by hard-blocking, the audio advantage provided by AMR-WB is entirely transformed into quality improvements. These amount almost one third on the speech quality indicator (SQI) scale ranging from zero to one. The capacity of 1times1 re-use networks is primarily limited through soft-blocking criteria. Four different quality criteria have been applied: SQI, frame erasure rate (FER), bad quality probability (BQP), and call drop rate (CDR). If only the subjective speech quality criteria were taken into account an increase in network capacity from 21% Erlang fractional load (EFL) for AMR-NB to 32% for AMR-WB is feasible. Since this quality indicator is rather related to general speech quality impression than to intelligibility, additional FER based quality criteria and CDR have been applied. Requiring additionally BQP lower than 5% and CDR lower than 2% limits the capacity of AMR-WB tight re-use networks to 21% EFL. Exactly the same capacity is achieved by AMR-NB, for which subjective speech quality is the more restrictive criterion. Exchanging the BQP criterion by the more restrictive criterion of mean FER per call lower than 2% for 95% of the subscribers leads to capacity advantages for AMR-NB due to lack of sufficiently robust AMR-WB codec modes and the higher latency in codec mode adaptation using tandem free operation. Results indicate that tight re-use networks should not exploit first glance quali- ty advantage of AMR-WB. Instead for the definition of admission control thresholds FER and BQP criteria shall be taken into consideration in addition to subjective speech quality impression.
    Mobile and Wireless Communications Summit, 2007. 16th IST; 08/2007
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    ABSTRACT: Smart quality enhancement (SQE) aims at improving traditional quality based power control algorithms by automatically adjusting the transmit power control decision thresholds to the prevailing traffic load conditions. During low traffic periods a high C/I threshold is required to protect calls against quality degradation caused by occasionally emerging interferers. At busy hour traffic level lower C/I decision thresholds are used to reduce the interference level for the most affected calls in the network. Applying this strategy the call is always best served. The benefit from SQE has been investigated by means of system level simulations. The simulation results show an optimum speech quality achieved by SQE over the whole range of feasible traffic load in the network. The percentage of satisfied users at low traffic load that would have been obtained with an optimum static decision threshold configured for busy hour traffic has been increased by SQE from about 93% to above 99%. Correspondingly the percentage of satisfied users at busy hour traffic load that would have been obtained with an optimum static decision threshold configured for low traffic has been improved from 90% up to 93%. Assuming an acceptable outage of 10% the quality improvement of about 3% can be traded-off against a capacity gain of about 10% to 15%. SQE is especially beneficial in network deployments providing mixed indoor and outdoor coverage
    Personal, Indoor and Mobile Radio Communications, 2006 IEEE 17th International Symposium on; 10/2006
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    ABSTRACT: During the last couple of years a series of voice quality and capacity enhancement features have been implemented in narrow-band deployments of GERAN (GSM/EDGE radio access networks) mobile radio networks. Recent field findings revealed call drop rate (CDR) to be the major limiting factor already in medium loaded AMR (adaptive multi rate) networks planned in tight frequency reuse due to excessive failures on the associated control channels (ACCH). The reason for this phenomenon observed at 20% to 30% EFL (Erlang fractional load) is the significant link level performance imbalance of up to 6 dB (in terms of C/I) between AMR 4.75/5.90 kbps voice codecs and signaling ACCH. In this study a novel strategy based on temporary ACCH overpower has been proposed as a practical and fully backwards compatible option to reduce the C/I gap and to improve the probability of successful decoding of the FACCH/SACCH frames. A full description of the CDR contributors (radio link timeout and handover failures) has been provided along with detailed system level simulation results. The initial evaluation of the novel approach is very promising, showing a significant soft capacity gain by substantially reducing CDR allowing a system load well above 30% EFL in homogeneous hexagonal networks. The suggested approach could be efficiently combined with current 3GPP standardization initiatives for control channel improvements in GERAN
    Personal, Indoor and Mobile Radio Communications, 2005. PIMRC 2005. IEEE 16th International Symposium on; 10/2005
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    ABSTRACT: The introduction of AMR-WB in 2G and 3G mobile networks represents a quantum leap in speech quality. The perceived voice quality is even superior to that offered in today's wire-line networks. A detailed study on the performance of the different AMR-WB codec types supporting GMSK as well as 8-PSK modulation has been performed based on system level simulations. The investigation is focused on speech quality, coverage and capacity that can be achieved in GERAN networks applying different frequency re-use patterns starting from a relaxed 4×3 down to a tight 1×1. The results show that neither additional sites nor a re-planning of the network is necessary for the introduction of AMR-WB. The dynamics of real codec mode adaptation traced along with the experienced radio link quality on an individual link reveal that an excellent speech quality can be achieved. The support of AMR-WB by both GERAN and UMTS offers high network homogeneity and a perfect symbiosis between 2G and 3G technologies providing an outstanding voice quality throughout the complete area of the multi-RAT network.
    Vehicular Technology Conference, 2005. VTC 2005-Spring. 2005 IEEE 61st; 01/2005
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    ABSTRACT: A novel smart interference reduction dynamic MAIO allocation (SIR-DMA) strategy for boosting voice capacity in synchronized GERAN networks with limited bandwidth is proposed. Global interference reduction is achieved by introducing into a standard DMA algorithm the new concept of concentric MAIO, associating an inner/outer MAIO with a mobile exposed to a low/high inter-site interference. Utilizing the inner/outer MAIO classification SIR-DMA tries to allocate calls in mutually interfering cells on orthogonal timeslots (TS) the degree of orthogonalization, however, depending on the combination of the associated MAIO types, thus minimizing the inter-site interference. Finally SIR-DMA selects the best TS/MAIO combination by taking additionally into account the intra-site interference. The initial evaluation shows a capacity gain of about 20% compared to conventional DMA. The interaction of SIR-DMA with the upcoming SAIC capable MS as well as state-of-the-art switched beam technology has been studied, achieving capacity figures close to the hard blocking limit of a real one by one reuse.
    Vehicular Technology Conference, 2004. VTC2004-Fall. 2004 IEEE 60th; 10/2004
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    ABSTRACT: With SI<sup>2</sup>R-DMA a novel procedure for boosting GERAN capacity in synchronized narrowband deployments has been proposed. The main goal of SI<sup>2</sup>R-DMA is both the inter- and intra-site interference reduction by intelligent radio resource management evolved from state-of-the-art DMA. For this purpose the new concept of concentric MAIO has been introduced for partitioning cells in inner and outer areas, whereas inner and outer mobiles of different interfering sites are allocated on orthogonal timeslots thus minimizing the mutual inter-site interference caused by random frequency hopping. The interaction between different sites in finding the optimum resource allocation with minimum inter-site interference has been modeled similar to a self-organizing neural network. A detailed description of SI<sup>2</sup>R-DMA has been provided accompanied by a variety of simulation results. First results are very promising, showing significant capacity gain of about 20% compared to conventional DMA.
    Personal, Indoor and Mobile Radio Communications, 2004. PIMRC 2004. 15th IEEE International Symposium on; 10/2004
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    ABSTRACT: Customer demand for wireless data services is rapidly increasing. The introduction of GPRS, EDGE and UMTS providing high bit rate radio bearer, however, is not the complete response for satisfying the demands of these new high quality services. An advanced quality of service QoS management is necessary to handle the characteristic requirements of both different service types and user expectations. A new QoS strategy is proposed and analyzed comprising 3GPP QoS parameters along with operator's specific weighting factors to define the appropriate QoS priority of each service type and user profile. Admission control as well as a deterministic up-and downgrading strategy are applied to ensure a minimum grade of service for low-priority applications. Furthermore, delay time sensitive services and premium users are granted a full bandwidth. Simulation results are provided to qualify the behavior of the proposed QoS strategy under different packet data load conditions. Especially in highly loaded and even overloaded GERAN networks the introduction of QoS provides significant benefits for the end user and offers powerful means to increase the service revenues according to the charging policy adopted by the network operator. The introduction of an appropriate QoS strategy is the prerequisite for an overlay deployment strategy of GSM/EDGE and UMTS.
    Personal, Indoor and Mobile Radio Communications, 2004. PIMRC 2004. 15th IEEE International Symposium on; 10/2004
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    ABSTRACT: An advanced QoS strategy comprising 3GPP QoS parameters along with operator specific weighting factors is used to define the appropriate QoS priority of each service type and user profile. A deterministic up- and downgrading strategy as well as admission control is applied to ensure both a minimum service level, defined by the operator for low-priority services, and a full bandwidth for delay time sensitive services and premium users. The simulation results show that, especially in highly loaded and even overloaded GSM/GPRS/EDGE networks, the introduction of QoS provides significant benefits for the end user and offers means to increase the service revenues according to the charging policy adopted by the network operator. The introduction of an appropriate QoS strategy is the prerequisite for an overlay deployment strategy of GSM/EDGE and UMTS. The efficiency of QoS management is crucial for all mobile network technologies and has high impact on fulfilling the demands of mobile subscribers with continuously growing expectations.
    Vehicular Technology Conference, 2004. VTC 2004-Spring. 2004 IEEE 59th; 06/2004
  • C.F. Ball, K. Ivanov, R. Mullner, F. Treml
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    ABSTRACT: Today's GSM and GPRS mobile networks are based on static 16 kbps terrestrial transport on the Abis interface using E1/T1 lines. For the introduction of the high data rate GPRS coding schemes such as CS4 with up to 20 kbps, EDGE with up to 59.2 kbps and high quality wideband adaptive multirate voice codecs with up to 23.85 kbps the terrestrial Abis capacity per air interface radio channel has to be extended. With FAAS a fully dynamic allocation strategy of n×16 kbps subslots is proposed on a per site basis for both voice and data to optimally match the capacity requirements of high bandwidth radio channels. The approach includes bringing up and releasing Abis resources out of the Abis resource pool on demand. The interaction with admission control, radio resource management and link adaptation involving upgrade and downgrade procedures is taken into account. To avoid unacceptable voice blocking a new concept for voice protection is included. Detailed simulation results for different cell configurations are presented for voice only and mixed voice and GPRS/EDGE packet data scenarios at varying load, which allow the appropriate dimensioning of the Abis resource pool per site. Depending on the cell load capacity gains up to 70% (typically 30-40% for medium load) can be achieved compared to a static Abis allocation approach promising considerable cost savings for operators.
    Vehicular Technology Conference, 2003. VTC 2003-Fall. 2003 IEEE 58th; 11/2003