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Zepernick, Hans-Juergen
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Publications (10 of 231) Show all publications
Chu, T. M. & Zepernick, H.-J. (2018). Optimal Power Allocation for Hybrid Cognitive Cooperative Radio Networks with Imperfect Spectrum Sensing. IEEE Access, 6, 10365-10380
Open this publication in new window or tab >>Optimal Power Allocation for Hybrid Cognitive Cooperative Radio Networks with Imperfect Spectrum Sensing
2018 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 10365-10380Article in journal (Refereed) Published
Abstract [en]

In this paper, two optimal power allocation strategies for hybrid interweave-underlay cognitive cooperative radio networks (CCRNs) are proposed to maximize channel capacity and minimize outage probability. The proposed power allocation strategies are derived for the case of Rayleigh fading taking into account the impact of imperfect spectrum sensing on the performance of the hybrid CCRN. Based on the optimal power allocation strategies, the transmit powers of the secondary transmitter and secondary relay are adapted according to the fading conditions, the interference power constraint imposed by the primary network (PN), the interference from the PN to the hybrid CCRN, and the total transmit power limit of the hybrid CCRN. Numerical results are provided to illustrate the effect of the interference power constraint of the PN, arrival rate of the PN, imperfect spectrum sensing, and the transmit power constraint of the hybrid CCRN on channel capacity and outage probability. Finally, comparisons of the channel capacity and outage probability of underlay, overlay, and hybrid interweaveunderlay CCRNs are presented to show the advantages of the hybrid spectrum access. OAPA

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2018
Keywords
amplify-and-forward relaying, Channel capacity, Cognitive radio, hybrid interweave-underlay scheme, Hybrid power systems, imperfect spectrum sensing, Interference, outage probability, power allocation, Power system reliability, Probability, Resource management, Sensors, Cognitive systems, Fading (radio), Rayleigh fading, Wave interference, Power allocations, Outages
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-15892 (URN)10.1109/ACCESS.2018.2792063 (DOI)000428148400001 ()2-s2.0-85041174409 (Scopus ID)
Available from: 2018-02-15 Created: 2018-02-15 Last updated: 2018-04-12Bibliographically approved
Louis, S., Hans-Jürgen, Z., Hung, T. & Charles, K. (2017). A Framework for Packet Delay Analysis of Point-to-Multipoint Underlay Cognitive Radio Networks. IEEE Transactions on Mobile Computing, 16(9), 2408-2421
Open this publication in new window or tab >>A Framework for Packet Delay Analysis of Point-to-Multipoint Underlay Cognitive Radio Networks
2017 (English)In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 16, no 9, p. 2408-2421Article in journal (Refereed) Published
Abstract [en]

This paper presents a queueing analytical framework for the performance evaluation of the secondary user (SU) packet transmission with service differentiation in a point-to-multipoint underlay cognitive radio network. The transmit power of the SU transmitter is subject to the joint outage constraint imposed by the primary user receivers (PU-Rxs) and the SU maximum transmit power limit. The analysis considers a queueing model for secondary traffic with multiple classes, and different types of arrival and service processes under a non-preemptive priority service discipline. The SU quality of service (QoS) is characterized by a packet timeout threshold and target bit error rate. Given these settings, analytical expressions of the packet timeout probability and average transmission time are derived for opportunistic and multicast scheduling. Moreover, expressions of the average packet waiting time in the queue and the total time in the system for each class of traffic are obtained. Numerical examples are provided to illustrate the secondary network performance with respect to various parameters such as number of PU-Rxs and SU receivers, SU packet arrival process, QoS requirements, and the impact of interference from the primary network to the secondary network.

Place, publisher, year, edition, pages
IEEE Computer Society, 2017
Keywords
Cognitive radio network; opportunistic and multicast scheduling; packet transmission time; arrival process; delay performance analysis
National Category
Communication Systems
Identifiers
urn:nbn:se:bth-11736 (URN)10.1109/TMC.2016.2621760 (DOI)000407399100002 ()
Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2017-09-29Bibliographically approved
Chu, T. M. & Zepernick, H.-J. (2017). Capacity Analysis of Two-Tier Networks with MIMO Cognitive Small Cells in Nagakami-m Fading. In: 2017 IEEE 13TH INTERNATIONAL CONFERENCE ON WIRELESS AND MOBILE COMPUTING, NETWORKING AND COMMUNICATIONS (WIMOB): . Paper presented at 13th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), Rome (pp. 457-463). IEEE
Open this publication in new window or tab >>Capacity Analysis of Two-Tier Networks with MIMO Cognitive Small Cells in Nagakami-m Fading
2017 (English)In: 2017 IEEE 13TH INTERNATIONAL CONFERENCE ON WIRELESS AND MOBILE COMPUTING, NETWORKING AND COMMUNICATIONS (WIMOB), IEEE , 2017, p. 457-463Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we consider a two-tier cellular network consisting of a primary macro cell base station (PMBS) which is overlaid by cognitive small cell base stations (CSBSs) to achieve efficient spectrum utilization. The deployment of two-tier cellular networks can provide higher capacity for the system but also causes cross-tier, intra-tier, and inter-tier interference within the cellular networks. Thus, we employ transmit and receive beamforming in the considered two-tier cellular network to mitigate interference. We first design the receive beamforming vector for a primary user (PU) such that it cancels all inter-tier interference from other PUs. Then, the transmit beamforming vectors at the secondary users (SUs) are designed to null out the cross-tier interference to the PUs. Further, the receive beamforming vectors at the SUs are designed to mitigate the crosstier interference from the PUs to the SUs. Finally, the transmit beamforming vector at the PMBS is designed to maximize the signal-to-interference-plus-noise ratio at the PUs. To quantify the performance of the system, we derive an expression for the channel capacity in the downlink from the CSBSs to the SUs. Numerical results are provided to reveal the effect of network parameters such as intra-tier interference distances, fading conditions, and number of antennas on the channel capacity of the SUs.

Place, publisher, year, edition, pages
IEEE, 2017
Series
IEEE International Conference on Wireless and Mobile Computing Networking and Communications-WiMOB, ISSN 2160-4886
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-15882 (URN)000419818000063 ()978-1-5386-3839-2 (ISBN)
Conference
13th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), Rome
Available from: 2018-02-09 Created: 2018-02-09 Last updated: 2018-02-22Bibliographically approved
Zepernick, H.-J. & Chu, T. M. (2017). Descriptive Statistical Analysis of Subjective Experiments in Mobile Imaging. In: Wysocki, TA Wysocki, BJ (Ed.), 11th International Conference on Signal Processing and Communication Systems, ICSPCS 2017: . Paper presented at 11th International Conference on Signal Processing and Communication Systems (ICSPCS), Surfers Paradise, Australia. IEEE
Open this publication in new window or tab >>Descriptive Statistical Analysis of Subjective Experiments in Mobile Imaging
2017 (English)In: 11th International Conference on Signal Processing and Communication Systems, ICSPCS 2017 / [ed] Wysocki, TA Wysocki, BJ, IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we provide a descriptive statistical analysis of subjective experiments in mobile imaging. Most of the statistical analyses of such experiments use condensed statistics such as mean opinion scores along with standard deviations. These statistics give only limited insights on the underlaying distribution of a data set. On the other hand, higher order statistics such as skewness and kurtosis provide additional information about a distribution but their qualitative interpretation is complicated. In order to alleviate these shortcomings, we advocate the use of box plots to efficiently visualize and compare distributions between different sets of image quality scores. Specifically, box plots serve the purposes of accounting for the diversity in image quality scores as well as supporting an intuitive qualitative interpretation of the results. It is shown by analysing two subjective experiments of the wireless imaging quality database that notched box plots are beneficial in quickly assessing the statistical significance among differences in such experiments. Further, box plots are used to identify those test material that received a wide diversity in image quality scores including outliers.

Place, publisher, year, edition, pages
IEEE, 2017
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-15991 (URN)000425961900044 ()978-1-5386-2887-4 (ISBN)
Conference
11th International Conference on Signal Processing and Communication Systems (ICSPCS), Surfers Paradise, Australia
Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-07-10Bibliographically approved
Chu, T. M., Zepernick, H.-J. & Phan, H. (2017). MAC Protocol for Opportunistic Spectrum Access in Multi-Channel Cognitive Relay Networks. In: IEEE Vehicular Technology Conference: . Paper presented at 85th IEEE Vehicular Technology Conference, Sydney. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>MAC Protocol for Opportunistic Spectrum Access in Multi-Channel Cognitive Relay Networks
2017 (English)In: IEEE Vehicular Technology Conference, Institute of Electrical and Electronics Engineers Inc. , 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we propose a medium access control (MAC) protocol for multi-channel cognitive cooperative radio networks (CCRNs). In this protocol, each secondary user (SU) senses for spectrum opportunities within M licensed bands of the primary users (PUs). To enhance the accuracy of spectrum sensing, we employ cooperative sequential spectrum sensing where SUs mutually exchange their sensing results. Moreover, the information obtained from cooperative spectrum sensing at the physical layer is integrated into the channel negotiation process at the MAC layer to alleviate the hidden terminal problem. Finally, the performance of the proposed MAC protocol in terms of aggregate throughput of the CCRNs is analyzed. Numerical results are provided to assess the impact of channel utilization by PUs, number of contenting CCRNs, number of licensed bands, and false alarm probability of SUs on the aggregate throughput. © 2017 IEEE.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2017
Series
IEEE Vehicular Technology Conference Proceedings
Keywords
Access control, Aggregates, Cognitive radio, Internet protocols, Network layers, Aggregate throughput, Co-operative spectrum sensing, Cognitive relay networks, False alarm probability, Hidden terminal problems, Medium access control protocols, Negotiation process, Opportunistic spectrum access, Medium access control
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-15852 (URN)10.1109/VTCSpring.2017.8108220 (DOI)000426875800040 ()2-s2.0-85040548983 (Scopus ID)9781509059324 (ISBN)
Conference
85th IEEE Vehicular Technology Conference, Sydney
Available from: 2018-02-02 Created: 2018-02-02 Last updated: 2018-04-19Bibliographically approved
Jamil, M., Zepernick, H.-J. & Yang, X. (2017). Multimodal function optimization using an improved bat algorithm in noise-free and noisy environments (10ed.). In: Modeling and Optimization in Science and Technologies: (pp. 29-49). Springer
Open this publication in new window or tab >>Multimodal function optimization using an improved bat algorithm in noise-free and noisy environments
2017 (English)In: Modeling and Optimization in Science and Technologies, Springer, 2017, 10, p. 29-49Chapter in book (Refereed)
Abstract [en]

Modern optimization problems in economics, medicine, and engineering are becoming more complicated and have a convoluted search space with multiple minima. These problems are multimodal with objective functions exhibiting multiple peaks, valleys, and hyperplanes of varying heights. Furthermore, they are nonlinear, non-smooth, non-quadratic, and can have multiple satisfactory solutions. In order to select a best solution among several possible solutions that can meet the problem objectives, it is desirable to find many such solutions. For these problems, the gradient information is either not available or not computable within reasonable time. Therefore, solving such problems is a challenging task. Recent years have seen a plethora of activities to solve such multimodal problems using non-traditional methods. These methods are nature inspired and are becoming popular due to their general applicability and effective search strategies. In this chapter, we assess the ability of an improved bat algorithm (IBA) to solve multimodal problems in noise-free and additive white Gaussian noise (AWGN) environments. Numerical results are presented to show that the IBA can successfully locate multiple solutions in both noise-free and AWGN environments with a relatively high degree of accuracy. © Springer International Publishing AG 2017.

Place, publisher, year, edition, pages
Springer, 2017 Edition: 10
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-14040 (URN)10.1007/978-3-319-50920-4_2 (DOI)2-s2.0-85014938295 (Scopus ID)
Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-28Bibliographically approved
Poreddy, M., Chu, T. M. & Zepernick, H.-J. (2017). On Outage Probability of Cooperative Cognitive Radio Networks Over k-mu Shadowed Fading. In: 2017 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC): . Paper presented at IEEE Wireless Communications and Networking Conference (WCNC), MAR 19-22, 2017, San Francisco, CA. IEEE
Open this publication in new window or tab >>On Outage Probability of Cooperative Cognitive Radio Networks Over k-mu Shadowed Fading
2017 (English)In: 2017 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we study the outage probability of a multiple relay cooperative cognitive radio network over kappa-mu shadowed fading channels where the relays use the decode and-forward (DF) protocol. The probability density function and cumulative distribution function of the total signal-to-noise ratio at the secondary receiver is derived for the case of selection combining. In particular, approximating the channels by Nakagami-m fading results in an analytical expression for the outage probability that can be expressed in terms of well- known functions. This approximation provides a good match when the parameters of the kappa-mu shadowed fading channels translate to integer values of fading severity parameter m. Numerical results are provided to illustrate the impact of system parameters on the outage probability for kappa-mu shadowed fading channels.

Place, publisher, year, edition, pages
IEEE, 2017
Series
IEEE Wireless Communications and Networking Conference, ISSN 1525-3511
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-14843 (URN)000403137600094 ()978-1-5090-4183-1 (ISBN)
Conference
IEEE Wireless Communications and Networking Conference (WCNC), MAR 19-22, 2017, San Francisco, CA
Available from: 2017-07-03 Created: 2017-07-03 Last updated: 2017-07-03Bibliographically approved
Huu, T. P., Quach, T. X., Tran, H., Zepernick, H.-J. & Sibomana, L. (2017). On Proactive Attacks for Coping With Cooperative Attacks in Relay Networks. In: 2017 23RD ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): BRIDGING THE METROPOLITAN AND THE REMOTE. Paper presented at 23rd Asia-Pacific Conference on Communications (APCC) - Bridging the Metropolitan and the Remote, DEC 11-13, 2017, Perth, AUSTRALIA (pp. 220-225).
Open this publication in new window or tab >>On Proactive Attacks for Coping With Cooperative Attacks in Relay Networks
Show others...
2017 (English)In: 2017 23RD ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): BRIDGING THE METROPOLITAN AND THE REMOTE, 2017, p. 220-225Conference paper, Published paper (Refereed)
Abstract [en]

Cooperative communications in which relays assist the transmission of signals from source to destination offer extended radio coverage and improved link reliable. However, transmitting signals with the help of a relay network may also open additional avenues for eavesdropper to overhear confidential information. Further, as jammers and eavesdroppers may cooperate to attack the relay network, offering secure communications becomes a challenging problem. To cope and reduce the effect of such cooperative attacks, we propose a proactive attack scheme in which the legitimate users generate jamming signals in an attempt to counteract such hostile cooperative attacks. In order to assess the security performance of the proactive attack scheme compared to a non-protection scheme, an analytical expression of the secrecy outage probability is derived. Numerical results for different system settings are provided showing that the proactive attack scheme can indeed significantly improve the security performance of the considered relay networks.

Series
Asia-Pacific Conference on Communications, ISSN 2163-0771
Keywords
PHYSICAL-LAYER SECURITY; MIMO WIRETAP CHANNEL; WIRELESS NETWORKS; ARTIFICIAL-NOISE; SECRECY; TRANSMISSION; SELECTION
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-16758 (URN)000434794800039 ()978-1-7405-2390-5 (ISBN)
Conference
23rd Asia-Pacific Conference on Communications (APCC) - Bridging the Metropolitan and the Remote, DEC 11-13, 2017, Perth, AUSTRALIA
Available from: 2018-07-09 Created: 2018-07-09 Last updated: 2018-07-10Bibliographically approved
Chu, T. M. & Zepernick, H.-J. (2017). On Secrecy Capacity of Full-Duplex Cognitive Cooperative Radio Networks. In: 2017 IEEE GLOBECOM WORKSHOPS (GC WKSHPS): . Paper presented at 36th IEEE Global Communications Conference (GLOBECOM), DEC 04-08, 2017, Singapore, SINGAPORE. IEEE
Open this publication in new window or tab >>On Secrecy Capacity of Full-Duplex Cognitive Cooperative Radio Networks
2017 (English)In: 2017 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we analyze the secrecy capacity of a full-duplex underlay cognitive cooperative radio network (CCRN) in the presence of an eavesdropper and under the interference power constraint of a primary network. The full-duplex mode is used at the secondary relay to improve the spectrum efficiency which in turn leads to an improvement of the secrecy capacity of the full-duplex CCRN. We utilize an approximation-and-fitting method to convert the complicated expression of the signal-to-interference-plus-noise ratio into polynomial form which is then utilized to derive an expression for the secrecy capacity. Numerical results are provided to illustrate the effect of network parameters such as transmit power, interference power limit, self-interference parameters of the full-duplex mode, and distances among links on the secrecy capacity. To reveal the benefits of the full-duplex CCRN, we compare the secrecy capacity obtained when the secondary relay operates in full-duplex and half-duplex mode.

Place, publisher, year, edition, pages
IEEE, 2017
Series
IEEE Globecom Workshops, ISSN 2166-0069
Keywords
AD HOC NETWORKS; INTERFERENCE; AUTHENTICATION; TRANSMISSION; SECURITY
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-16050 (URN)000426984700093 ()978-1-5386-3920-7 (ISBN)
Conference
36th IEEE Global Communications Conference (GLOBECOM), DEC 04-08, 2017, Singapore, SINGAPORE
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-04Bibliographically approved
Chu, T. M. & Zepernick, H.-J. (2017). Outage Probability and Secrecy Capacity of a Non-orthogonal Multiple Access System. In: Wysocki, TA Wysocki, BJ (Ed.), 11th International Conference on Signal Processing and Communication Systems, ICSPCS, 2017: . Paper presented at 11th International Conference on Signal Processing and Communication Systems (ICSPCS), surfers Paradise, Australia. IEEE
Open this publication in new window or tab >>Outage Probability and Secrecy Capacity of a Non-orthogonal Multiple Access System
2017 (English)In: 11th International Conference on Signal Processing and Communication Systems, ICSPCS, 2017 / [ed] Wysocki, TA Wysocki, BJ, IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we analyze the outage probability and secrecy capacity of a non-orthogonal multiple access (NOMA) system in the presence of an eavesdropper. In order to enhance spectral efficiency, a base station communicates with two users simultaneously in the same frequency band by superpimposing the transmit signals to the users in the power domain. Specifically, the user with the worse channel conditions is allocated higher power such that it is able to directly decode its signal from the received superimposed signal. At the user with the better channel conditions, the interference due to NOMA is processed by successive interference cancelation. Given these system settings and accounting for decoding thresholds, we analyze the outage probability of the NOMA system over Rayleigh fading channels. Furthermore, based on the locations of the users and eavesdropper, the secrecy capacity is analyzed to assess the level of security provided to the legitimate users in the presence of an eavesdropper. Here, the decoding thresholds of legitimate users and eavesdropper are also included in the analysis of the secrecy capacity. Through numerical results, the effects of network parameters on system performance are assessed as well as the the superiority of NOMA in terms of secrecy capacity over traditional orthogonal multiple access.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Communication channels (information theory), Decoding, Fading channels, Probability, Rayleigh fading, Signal processing
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-15989 (URN)000425961900057 ()978-1-5386-2887-4 (ISBN)
Conference
11th International Conference on Signal Processing and Communication Systems (ICSPCS), surfers Paradise, Australia
Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-07-10Bibliographically approved
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