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  • 201.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Hung, Tran
    Wireless Information and Power Transfer in an Underlay Cognitive Radio Network2014Ingår i: 2014 8TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS), IEEE, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we consider a secondary network with simultaneous wireless information and power transfer in a spectrum sharing scenario. In particular, a secondary user (SU) transmitter communicates with multiple SU receivers (SU-Rxs) under the peak interference power constraint of the primary user receiver and the SU maximum transmit power limit. We apply a channel quality-based threshold and exploit opportunistic scheduling. Specifically, an SU-Rx with best channel condition among a set of SU-Rxs satisfying the threshold is scheduled for data transmission. The remaining SU-Rxs with channel condition below the threshold, harvest the radio frequency energy. Analytical expressions of the SU ergodic capacity, symbol error rate, throughput, and energy harvesting are obtained. An optimal threshold satisfying a given target outage probability is determined. Numerical results are provided to investigate the impact of different parameters on the secondary network performance.

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  • 202.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Kabiri, Charles
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Tran, Hung
    Outage Performance Analysis of Cognitive Relay Networks with BRS and MMRS2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we consider a spectrum sharing system where a secondary user (SU) transmitter (SU-Tx) communicates with an SU receiver (SU-Rx) with the help of multiple secondary relays (SRs) in the presence of a single primary network link. In particular, the SU-Tx and SR are subject to their maximum transmit power limits and the timeout constraint of the primary user (PU). Moreover, we assume that the relay selection is based on either best relay selection (BRS) or max-max relay selection (MMRS). In BRS, a single relay having the best end-to-end channel condition among the SRs is selected for cooperation between the source and the destination. However, the selected relay may not experience the best source-relay channel and relay-destination channel at the same time. To overcome the limitation of selecting the same relay for both reception and transmission, MMRS uses the best relay of the SU-Tx→SR link for reception at the relay and the best relay of the SR→SURx link for transmission to the destination. Specifically, we compare the performance for BRS and MMRS in terms of the outage probability, and study the impact of the number of SRs, PU transmit power and different channel mean powers of interference links on the secondary network performance. Furthermore, based on the performance of the MMRS and assuming that automatic repeat request (ARQ) is implemented for packet retransmission, we investigate the outage probability for delay limited applications. The numerical results indicate that the MMRS outperforms BRS when more than one SRs are deployed. The secondary network outage probability is reduced when the number of SRs and the number of retransmissions become large. It is also shown that the interference from the PU has a significant impact on the secondary network performance.

  • 203.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Tran, Hung
    Achievable Secrecy Capacity in an Underlay Cognitive Radio Network2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we consider a spectrum sharing cognitive radio network where a secondary user (SU) transmitter (SU-Tx) communicates with multiple SU receivers (SU-Rxs). There exist multiple eavesdroppers (EAVs) who illegally listen to the secondary network communication. Further, the primary network consists of a primary user (PU) transmitter serving multiple PU receivers. In particular, the SU-Tx transmit power is subject to the joint constraint of PU outage and SU maximum transmit power limit. Moreover, we investigate the secondary network physical layer security in terms of average secrecy capacity for both cases of known and unknown channel information of the EAV at the SU-Tx. Numerical results are provided to evaluate the impact of the number of PU-Rxs, number of EAVs, number of SU-Rxs, and channel mean powers among users on the SU average secrecy capacity.

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  • 204.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Tran, Hung
    On Physical Layer Security for Reactive DF Cognitive Relay Networks2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper analyzes the physical layer security for cognitive relay networks under the peak interference power constraint of the primary user receiver. In particular, a secondary user (SU) transmitter communicates with an SU receiver through the help of multiple secondary relays (SRs) using a decode-and- forward (DF) protocol. There exist multiple eavesdroppers (EAVs) who illegally listen to the secondary network communication. We consider a reactive DF scheme, and only the SRs that satisfy a decoding threshold participate in the relay selection. Analytical expressions of the probability of existence of secrecy capacity and secrecy outage probability are obtained. Numerical results are provided to evaluate the impact of the number of SRs, number of EAVs and channel mean powers on the secondary system security. We also investigate the effect of the interference from the primary network to the secondary network performance. Moreover, the performance of proactive DF is analyzed for the purpose of comparison.

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  • 205.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Tran, Hung
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Kabiri, Charles
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Packet transmission time for cognitive radio networks considering interference from primary user2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate a downlink model for underlay cognitive radio networks (CRNs). In particular, we assume that the secondary transmitter (SU-Tx) sends common packets to secondary receivers (SU-Rx) under the outage constraint of a single primary user (PU) and the peak transmit power constraint of the SU-Tx. All channels undergo Rayleigh fading. Given these settings, an adaptive transmit power policy for the SU-Tx is considered. Moreover, the cumulative distribution function (CDF) and probability density function (PDF) for packet transmission time are derived to analyze the timeout probability, the average packet transmission time and the average time a packet spends in the system for the SU-Rx having the best channel condition. Numerical results are provided to investigate the impact of the PU transmit power and channel mean powers on secondary network performance. The results show that when the number of SU-Rx becomes large, the timeout probability and the packet average time in the system decrease to a minimum.

  • 206.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Tran, Hung
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Kabiri, Charles
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Timeout Probability for Cognitive Radio Networks2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Cognitive radio networks (CRNs) promise solutions to increase the spectrum utilization in wireless systems. In underlay cognitive radio spectrum sharing, the non-licensed users referred to as secondary users (SUs) are allowed to transmit simultaneously over the same frequency of licensed users known as primary users (PUs) as long as the interference to the primary receiver (PU-Rx) caused by the secondary transmitter (SU-Tx) remains below a predefined threshold. In this work, we investigate a downlink model for CRN. In particular, we assume that the SU-Tx sends common packets to secondary receivers (SU-Rx) under the outage constraint of a single PU and the peak transmit power constraint of the SU-Tx. All channels undergo Rayleigh fading. Given these settings, an adaptive transmit power policy for the SU-Tx is obtained. Moreover, we derive the cumulative distribution function (CDF) for minimum packet transmission time to analyze the timeout probability for SU-Rx having the best channel condition. Numerical results are provided to investigate the impact of PU transmit power and channel mean power gain on secondary network performance. The secondary system performance does not only depend on the outage constraint imposed by the PU and the SU peak transmit power but also on the interference from PU-Tx to SU-Rx. By increasing the number of SU-Rx, the timeout probability decreases to a minimum value.

  • 207.
    Sibomana, Louis
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Tran, Hung
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rutabayiro
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Packet Transmission for Multiservice Cognitive Radio Networks with Finite Buffer Capacity2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we analyze the secondary network transmission given a packet timeout threshold and a target bit error rate (BER) in a downlink multiservice spectrum sharing cognitive radio network (CRN). Under the joint constraint of primary user (PU) outage probability and secondary user (SU) peak transmit power, the adaptive transmit power policy of the SU transmitter (SU-Tx) is obtained. The throughput is maximized by transmitting to the secondary receiver (SU-Rx) having the best channel condition. We maintain fairness with a minimum resource guarantee assigned to each packet of a class of service. Accordingly, the average packet transmission time is determined. In addition, employing an M/G/1/B queueing model, the packet blocking probability is given to develop expressions of the average throughput and packet loss probability for the secondary class of service. Moreover, the quality of experience (QoE) is evaluated based on the relationship between the packet loss probability and mean opinion score (MOS). The results show that the secondary network achieves the stable transmission quality and minimizes packet loss when the number of SU-Rx becomes large.

  • 208. Sjögren, Thomas
    et al.
    Vu, Viet Thuy
    Pettersson, Mats
    Zepernick, Hans-Jürgen
    Gustavsson, Anders
    Speed Estimation Experiments for Ground Moving Targets in Low Frequency UWB2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an iterative method to estimate the Normalised Relative Speed (NRS) of ground moving targets in Ultra Wideband (UWB) wide beam Synthetic Aperture Radar (SAR) using one antenna. The number of iterations depends on the separation between processed NRS and true target NRS. The NRS estimate is based on a chirp rate estimator in azimuth direction of the SAR image. The paper derives an analytical expression of the azimuth phase information based on the moving target NRS and the NRS used in the image formation. The method has been tested on real data from the CARABAS-II SAR system showing good results.

  • 209.
    Soffritti, Jacopo
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Duong, Trung Q.
    Merani, Maria Luisa
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Performance Analysis of Randomized Distributed Space-Time Codes over Composite Gamma/Lognormal Fading Channels2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work investigates the end-to-end performance of randomized distributed space-time codes with complex Gaussian distribution, when employed in a wireless relay network. The relaying nodes are assumed to adopt a decode-and-forward strategy and transmissions are affected by small and large scale fading phenomena. Extremely tight, analytical approximations of the end-to-end symbol error probability and of the end-to-end outage probability are derived and successfully validated through Monte-Carlo simulation. For the high signal-to-noise ratio regime, a simple, closed-form expression for the symbol error probability is further provided.

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  • 210. Soffritti, Jacopo
    et al.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Merani, Maria Luisa
    Performance Analysis of Randomized Distributed Space-Time Codes in Nakagami-m Fading2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a performance analysis of randomized distributed space-time codes (RDSTCs) in Nakagami-m fading channels over a multiple Decode-and-Forward (DF) relay network. The performance is assessed in terms of symbol error probability (SEP) and outage probability (OP). The results of this research provide exact analytical expressions for these two performance metrics. In addition, the diversity gain of the considered system is derived from these expressions and compared with some results already presented in literature to verify its soundness. Finally, numerical results for some example scenarios are provided to illustrate applications of the derivedexpressions for performance analysis.

  • 211.
    Tran, Dang Ninh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Spherical Light-Weight Data Hiding in 360-Degree Videos with Equirectangular Projection2019Ingår i: 2019 12TH INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGIES FOR COMMUNICATIONS (ATC 2019) / [ed] Minh, NC; VanNghia, N; Tan, TD; Toan, ND, IEEE Computer Society , 2019, s. 56-62Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we propose a spherical light-weight data hiding technique for 360-degree videos with equirectangular projection between sphere and plane. In particular, computationally efficient least significant bit (LSB) data hiding is applied to the color encoded equirectangular projection of the sphere. As viewers put more attention to the areas around the equator of a 360-degree video compared to the poles, LSB data hiding may be performed in the regions around the poles without causing perceptually significant quality degradation. In addition, the equirectangular projection induces a huge amount of data redundancy in the areas near the poles which increases the capacity available for LSB data hiding. A performance assessment of the proposed spherical light-weight data hiding technique is conducted using the weighted-to-spherically-uniform peak-signal-to-noise ratio (WS-PSNR) and the Craster parabolic projection PSNR (CPP-PSNR). Because both metrics take the non-linear relationship between samples on the sphere and the samples mapped to the plane into account, they are well suited for assessing the performance of the spherical LSB data hiding technique. Numerical results are provided for scenarios in which a 360-degree cover video carries a secret video using different numbers of bit planes. It is shown that video fidelity in terms of WS-PSNR and CPP-PSNR is indeed kept high in the 360-degree stego-video as long as the LSB data hiding is performed in the areas around the poles. © 2019 IEEE.

  • 212.
    Tran, Dang Ninh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Spherical LSB Data Hiding in 360° Videos Using Morphological Operations2019Ingår i: 13th International Conference on Signal Processing and Communication Systems, ICSPCS 2019 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Steganography has been widely used to embed secret data in cover multimedia carriers including digital image, audio, and video files such that the confidential information being communicated is hidden. Immersive multimedia, e.g., 360° videos, have recently received increased attention as promising applications for the Internet and 5G mobile networks. In this paper, we focus on using steganography for hiding secret data in an immersive multimedia carrier. Specifically, a spherical least significant bit (LSB) data hiding approach is proposed to embed secret videos in 360° cover videos along with morphological operations. Due to viewers are paying less attention to the North and South Poles compared to the Equator region of 360° videos, LSB data hiding is performed around the poles of the equirectangular projection of the sphere to the plane. Data hiding capacity is increased by using morphological operations in the remaining mid-region around the Equator which broadens the edge area for embedding secret data. The proposed spherical LSB data hiding technique may be used to hide secret videos or other confidential data in 360° cover videos. It can also be used to increase available bandwidth for communication purposes as long as embedded data has no significant impact on the quality as perceived by the end-user. A performance assessment of the proposed approach is conducted with respect to data hiding capacity and objective perceptual video quality. Numerical results are provided for a wide range of scenarios illustrating the trade-offs between capacity and quality. © 2019 IEEE.

  • 213.
    Tran, Dang Ninh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    On LSB Data Hiding in High-Definition Images Using Morphological Operations2019Ingår i: Proceedings - 2019 19th International Symposium on Communications and Information Technologies, ISCIT 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 386-391Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of steganography is to conceal the presence of communication by way of hiding secret data in perceptually irrelevant parts of a cover object. In this paper, we propose a method for hiding secret images in edge regions of high-definition (HD) images because the human visual system is less sensitive to intensity changes in these regions. In particular, least significant bit substitution is used to embed a secret image in the edge regions of a HD cover image. The edge regions are obtained using a Canny edge detector followed by morphological operations which are used to control the hiding capacity. A performance assessment of the proposed method reveals the trade-off between capacity, detectability, and perceptibility of the hidden data. © 2019 IEEE.

  • 214.
    Tran, Dang Ninh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    On Moderately Significant Bit Data Hiding Techniques for High-Definition Images2018Ingår i: International Conference on Advanced Technologies for Communications, IEEE Computer Society , 2018, s. 47-52Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study moderately significant bit data hiding techniques for high-definition (HD) images. In contrast to least significant bit data hiding, we explore the potential of HD images to engage higher order bits for increasing the capacity of hiding secret images. In particular, the number of secret images embedded in moderately significant bits of a given cover image is successively increased to study the impact of this data hiding approach on image fidelity and image quality in the context of HD images. A comprehensive performance assessment is conducted on the stego-image carrying the secret images in terms of peak-signal-to-noise ratio (PSNR) and structural similarity (SSIM) index. It is shown that HD images indeed offer the potential of hiding several images within certain image fidelity and objective perceptual image quality constraints of the resulting stego-HD images. © 2018 IEEE.

  • 215.
    Tran, Dang Ninh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    On the Positioning of Moderately Significant Bit Data Hiding in High-Definition Images2018Ingår i: 2018 12TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS) / [ed] Wysocki, TA Wysocki, BJ, IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile services have seen a shift from voice services toward visual stimuli-based services ranging from mobile imaging over mobile gaming to upcoming mobile extended reality applications. In this paper, given the increased resolutions of the related mobile multimedia formats, we propose and examine positioning strategies for light-weight data hiding of secret images in moderately significant bits of high-definition (HD) cover images. Apart from linear and random positioning, visual attention mechanisms of the human visual system are addressed by separately utilizing either the background or center of the HD cover image for data hiding. A performance assessment of these positioning strategies is conducted in terms of the peak-signal-to-noise ratio (PSNR), structural similarity (SSIM) index, and visual information fidelity (VIF). It is shown that HD cover images indeed can carry more than a single secret image until noticeable quality loss is observed. Further, it is revealed that linear positioning of secret images in the whole, background, or center of HD cover images outperforms random positioning. As for the utilized performance metrics, it has been observed that PSNR cannot differentiate among the positioning strategies as it measures pixel-by-pixel differences and hence removes the impact of the position of the hidden data. As for the two quality metrics, compared to the SSIM index, VIF is found to stronger differentiate among the performance of the considered positioning strategies.

  • 216. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Average Waiting Time of Packets with Different Priorities in Cognitive Radio Networks2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the average waiting time of packets with different priorities in cognitive radio networks (CRN) using a preemptive priority queuing system. Specifically, we consider two scenarios for CRN, the first with the secondary user (SU) sensing at the beginning of each time slot and the other with the SU having continues sensing ability. Our analysis shows that the average waiting time of packets for the SU does not only depend on the size of packets and arrival rate of the SU traffic but also depends on the arrival rate and size of packets from primary users (PU). Moreover, the results show that an SU with continuous sensing ability can utilize spectrum better than sensing at the beginning of each time slot.

  • 217.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Duong, Quang Trung
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Delay performance of cognitive radio networks for point-to-point and point-to-multipoint communications2012Ingår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, we analyze the packet transmission time in spectrum sharing systems where a secondary user (SU) simultaneously accesses the spectrum licensed to primary users (PUs). In particular, under the assumption of an independent identical distributed Rayleigh block fading channel, we investigate the effect of the peak interference power constraint imposed by multiple PUs on the packet transmission time of the SU. Utilizing the concept of timeout, exact closed-form expressions of outage probability and average packet transmission time of the SU are derived. In addition, employing the characteristics of the M/G/1 queuing model, the impact of the number of PUs and their peak interference power constraint on the stable transmission condition and the average waiting time of packets at the SU are examined. Moreover, we then extend the analysis for point-to-point to point-to-multipoint communications allowing for multiple SUs and derive the related closed-form expressions for outage probability and successful transmission probability for the best channel condition. Numerical results are provided to corroborate our theoretical results and to illustrate applications of the derived closed-form expressions for performance evaluation of cognitive radio networks.

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  • 218. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    On the Performance of Spectrum Sharing Systems Over Alpha-Mu Fading Channel for Non-identical Mu Parameter2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Spectrum sharing is a promising approach in cognitive radio networks to improve the spectrum utilization of wireless communication systems. In this paper, we analyze the performance of spectrum sharing systems under the peak interference constraint for a general fading model, namely the Alpha-Mu fading channel. In particular, we derive expressions for statistical characteristics such as probability density function and cumulative distribution function of the end-to-end signal-tonoise ratio for dissimilar parameter Mu. Using these statistics, we obtain the closed-form expressions for outage probability, amount of fading and approximate ergodic capacity for the considered spectrum sharing system. Finally, Monte Carlo simulations are presented to verify the analytical results.

  • 219. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Performance Analysis of Cognitive Relay Networks Under Power Constraint of Multiple Primary Users2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cognitive relaying is a promising technique to improve spectrum utilization in mobile networks. In this paper, we consider a scenario in which a secondary transmitter communicates with a secondary receiver by the help of a secondary relay. The secondary user should adjust its transmission power in order to not cause any harmful interference to the multiple primary users operating in the licensed spectrum. In this context, we investigate the end-to-end performance of cognitive relay networks in terms of outage probability and ergodic capacity over Nakagami-m fading channels. A closed-form expression for outage probability and an approximation for ergodic capacity are derived. Furthermore, the presented numerical examples illustrate the impact of the number of primary users on the performance of cognitive relay networks.

  • 220. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Performance of a Spectrum Sharing System over Nakagami-m Fading Channels2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we derive the probability density function and cumulative distribution function of packet transmission time in a spectrum sharing system. In combination with the time-out characteristics of packets, we further study the outage probability and average transmission time under peak power interference constraint over Nakagami-m fading channel. Especially, we employ the M/G/1 queuing model to calculate the average waiting time of packets and average number of packets waiting in the queue of a secondary user. The numerical results show the importance of the peak interference power constraint on the delay of packets at the secondary user.

  • 221. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Queuing Analysis For Cognitive Radio Networks Under Peak Interference Power Constraint2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the effect of peak interference power constraint on outage probability and transmission time of packets for secondary user (SU) in a spectrum sharing environment. In the considered cognitive radio network scenario, a secondary user transmitter sends its packets over a Rayleigh fading channel. In combination with the analysis of time out characteristics, queuing models are deployed to evaluate average transmission time of packets, average waiting time of packets, and average number of packets waiting in the queue of the cognitive user.

  • 222.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Hagos, Maarig Aregawi
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Mohamed, Marshed
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Impact of Primary Networks on the Performance of Secondary Networks2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the performance of a single-input and multiple-output cognitive radio network over Rayleigh fading. In particular, we assume that secondary transmitter (SU-Tx) and primary transmitter (PU-Tx) are equipped with a single antenna while secondary receiver (SU-Rx) and primary receiver (PU-Rx) have multiple antennas. Additionally, the SU-Tx transmit power is subject to outage constraint of the primary network and peak transmit power of the secondary network. Given these settings, an adaptive transmit power allocation policy for the SU-Tx, a closed-form expression for outage probability, and an approximation for ergodic capacity are obtained. These formulas will be used to examine the impact of the PU-Tx transmit power, the number of antennas at receivers, and channel mean powers on the performance of the secondary network. More importantly, our results reveal that the SU-Tx using the power allocation policy can obtain optimal performance.

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  • 223.
    Tran, Hung
    et al.
    Malardalen Univ, S-72123 Vasteras, Sweden..
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling. Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation. Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Phan, Hoc
    Univ Reading, Reading RG6 6AY, Berks, England..
    On Throughput and Quality of Experience in Cognitive Radio Networks2016Ingår i: 2016 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a performance analysis for cognitive radio networks (CRNs) under the outage probability constraint of the primary user and peak transmit power constraint of the secondary user is conducted. Given an automatic repeat request protocol, analytical expressions for the packet delay and throughput of the CRN are derived. Most importantly, these expressions can be used to understand the quality of experience on web services which are assumed to be offered by the considered CRN.

  • 224.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Impact of Secondary Network on the Security of Primary Network2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In this study, we investigate the impact of a secondary user on the security of the primary user in a cognitive radio network. In particular, we consider a spectrum underlay network consisting of a pair of primary users, a pair of secondary users, and an eavesdropper, operating in the same spectrum. The secondary user is allowed to simultaneously access the licensed frequency bands of the primary user as long as the outage probability of the primary user is kept below a predefined threshold, while the eavesdropper illegally listens to the communication of the primary network. Given these settings, an adaptive transmit power allocation policy, a closed-form expression for the outage probability, and an analytical expression for the probability of existence of non-zero secrecy capacity are formulated. Simulations show that the existence of a secondary network can enhance the probability of non-zero secrecy capacity of the primary network by causing interference to the eavesdropper.

  • 225.
    Tran, Hung
    et al.
    Malardalen Univ, SWE.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Proactive Attack: A Strategy for Legitimate Eavesdropping2016Ingår i: 2016 IEEE Sixth International Conference on Communications and Electronics (ICCE), IEEE, 2016, s. 457-461Konferensbidrag (Refereegranskat)
  • 226.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Chan, Dai Truyen Thai
    Outage Performance of Cognitive Radio Networks under Outage Constraint of Multiple Primary Users and Transmit Power Constraint of Secondary User2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the outage performance of a cognitive radio network under the joint constraint of multiple primary users (PUs) and a secondary user (SU) is investigated. More specifically, the SU can adjust its transmit power to satisfy the outage probability constraint of multiple PUs and its own transmit power constraint for communication. The adaptive transmit power policy and closed-form expression for the outage probability are derived. On the basis of these formulas, the impact of the channel gains of the PUs and those of the interference links from the PUs to the SU on the performance of the secondary network is evaluated. Especially, our results show a relationship between the number of the active PUs on the licensed frequency bands and the outage performance of the secondary network. Also, the performance of secondary network can be improved by extending the bandwidth over a number of licensed frequency bands.

  • 227.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Phan, Hoc
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Outage Probability, Average Transmission Time, and Quality of Experience for Cognitive Radio Networks over General Fading Channels2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we examine the delay performance in cognitive radio networks (CRNs) over general fading channels where secondary users are allowed to simultaneously access the spectrum licensed by primary users. In particular, subject to the peak interference power constraint, we investigate the effect of general fading channels on the delivery delay of data packets and acknowledgements (ACKs). A lower bound of outage probability and an upper bound of average transmission time are derived by utilizing the concept of timeout. Specifically, we apply the above results to investigate the quality of experience (QoE) for various fading channels, such as one-sided Gaussian, Rayleigh, Nakagami-m and Weibull channels. The numerical results indicate that the delay of ACKs under severe fading leads to a degradation of system performance.

  • 228.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Phan, Hoc
    Cognitive cooperative networks with decode-and-forward relay selection under interference constraints of multiple primary users2015Ingår i: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, nr 10, s. 1433-1443Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we study the performance of cognitive cooperative radio networks under the peak interference power constraints of multiple primary users (PUs). In particular, we consider a system model where the secondary user communication is assisted by multiple secondary relays (SRs) that operate in the decode-and-forward mode to relay the signal from a secondary transmitter to a secondary receiver. Moreover, we assume that the transmit powers of the secondary transmitter and the SRs are subject to the peak interference power constraints of multiple PUs that operate in their coverage range. Given this system setting, we first derive the cumulative distribution function of the instantaneous end-to-end signal-to-noise ratio. Then, we obtain a closed-form expression for the outage probability and an exact expression for the symbol error probability of the considered network. These tractable formulas enable us to examine the impact of the presence of multiple PUs on the performance of the considered spectrum sharing system. Furthermore, our numerical results show that system performance is improved significantly when the number of SRs increases or the channel mean power from the secondary user to the PUs is low. Also, any increase in the number of PUs in the coverage range of the secondary transmitter or the SRs leads to degradation in system performance. Finally, Monte Carlo simulations are provided to verify the correctness of our analytical results.

  • 229.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Phan, Hoc
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Cognitive Proactive and Reactive DF Relaying Schemes under Joint Outage and Peak Transmit Power Constraints2013Ingår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 17, nr 8, s. 1548-1551Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, outage performance of cognitive cooperative radio networks using two decode-and-forward (DF) schemes is investigated. Subject to the joint outage constraint of the primary user and the peak transmit power constraint of the secondary user, adaptive power allocation policies for the secondary transmitter and secondary relays are studied. Based on these strategies, expressions for the outage probability of proactive and reactive DF schemes are obtained. Interestingly, our results show that an increase in the transmit power of the primary transmitter (PU-Tx) does not always degrade the performance of the secondary network. In fact, the PU-Tx transmit power is a substantial parameter that the secondary users can adapt to in order to improve the system performance. The numerical results additionally show that the performance of the reactive DF scheme outperforms the proactive DF scheme if the outage threshold in the first hop of the reactive DF scheme is less than that of the proactive scheme.

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  • 230.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Phan, Hoc
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Impact of the Number of Antennas and Distances Among Users on Cognitive Radio Networks2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the impact of the number of antennas and distances among users on the performance of a spectrum sharing system. In particular, we assume that a secondary transmitter is equipped with a single antenna while both secondary receiver and primary receiver have multiple antennas. Also, it is assumed that the secondary users are subject to the peak interference power constraint. On this basis, the cumulative distribution function and probability density function for the signal-to-noise ratio are derived for Rayleigh fading channels. Moreover, using these results, we obtain closed-form expressions for the outage probability, ergodic capacity and an exact expression for symbol error probability. These formulas allow us to examine the impact of the number of antennas of the SU-Rx, the PU-Rx and distance among users on the system performance. Finally, Monte-Carlo simulations are provided to verify our analytical results.

  • 231.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Phan, Hoc
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Sibomana, Louis
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Performance Analysis of a Cognitive Radio Network with a Buffered Relay2015Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, nr 2, s. 566-579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we analyze the packet transmission time in a cognitive cooperative radio network (CCRN) where a secondary transmitter (SU-Tx) sends packets to a secondary receiver (SU-Rx) through the help of a secondary relay (SR). In particular, we assume that the SU-Tx and SR are subject to the joint constraint of the timeout probability of the primary user (PU) and the peak transmit powers of the secondary users. On this basis, we investigate the impact of the transmit power of the PUs and channel mean powers on the packet transmission time of the CCRN. Utilizing the concept of timeout, adaptive transmit power allocation policies for the SU-Tx and SR are considered. More importantly, analytical expressions for the endto- end throughput, end-to-end packet transmission time, and stable condition for the SR operation are obtained. Our results indicate that the second hop of the considered CCRN is not a bottleneck if the channel mean powers of the interference links of the networks are small and the SR peak transmit power is set to a high value.

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  • 232.
    Tran, Hung
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Phan, Hoc
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Trinh, Pham Quang
    Cognitive Cooperative Networks with Cluster-Based Relaying under Interference Constraints2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we consider the outage performance of a cognitive cooperative radio network (CCRN) in which the secondary base station (SBS) transmits signals to multiple secondary receivers (SU-Rx) through the help of multiple secondary relays (SRs). It is assumed that the SRs are geographically distributed in clusters and that the considered network operates in a Rayleigh environment. In addition, we assume that the transmit powers of the SBS and SRs are subject to peak interference power constraints of the primary users (PUs) in their respective coverage range. Specifically, a closed-form expression for the outage probability of the SU-Rx with the worst channel condition is derived for independently distributed Rayleigh fading. The obtained outage expression is further utilized to examine the impact of the channel mean powers, the number of SRs distributed in each cluster and the number of clusters on the system performance.

  • 233.
    Tran, Hung
    et al.
    Mälardalen University, SWE.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Sibomana, Louis
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Performance of cognitive radio networks under interference constraints of multiple primary users2016Ingår i: 2016, 10th International Conference on Signal Processing and Communication Systems, ICSPCS 2016 - Proceedings, IEEE, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the performance of point-to-point communication in spectrum sharing systems under the peak interference power constraint of multiple primary users. In particular, we assume that the channels undergo independent but not necessarily identically distributed Nakagami-m fading with integer values of fading severity parameter m. The cumulative distribution function and probability density function for the signal-to-noise ratio are derived. Based on these formulas, we obtain analytical expressions for the outage probability, the ergodic capacity, and the symbol error probability. Numerical results are also provided to investigate the impact of the peak interference power-to-noise ratio, the number of primary users, and fading parameters on the performance of the secondary network. © 2016 IEEE.

  • 234. Vo, Nguyen-Son
    et al.
    Duong, Quang Trung
    Shu, Lei
    Du, Xu
    Zepernick, Hans-Jürgen
    Cheng, Wenping
    Cross-layer Design for Video Replication Strategy over Multihop Wireless Networks2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we propose a cross-layer optimization approach for replication of video streaming over multihop wireless network by jointly taking into account application, network, medium access control, and physical layers. Specifically, we design a middleware replication strategy layer with a stack profile, in which parameters across the hops and all considered layers are exchanged for optimal video replication. The simulation results demonstrate that our method improves the replication strategy performance in terms of user-perceived video quality. In turn, it satisfies the heterogeneous receive bandwidth constraint of users for efficiently using the network bandwidth compared to other optimal replication strategies without cross-layer approach.

  • 235. Vo, Nguyen-Son
    et al.
    Duong, Trung Quong
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    A Cross-Layer Optimized Scheme and Its Application in Mobile Multimedia Networks With QoS Provision2016Ingår i: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 10, nr 2, s. 817-830Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To cope with the rapid growth of multimedia applications that requires dynamic levels of quality of service (QoS), cross-layer (CL) design, where multiple protocol layers are jointly combined, has been considered to provide diverse QoS provisions for mobile multimedia networks. However, there is a lack of a general mathematical framework to model such CL scheme in wireless networks with different types of multimedia classes. In this paper, to overcome this shortcoming, we therefore propose a novel CL design for integrated real-time/non-real-time traffic with strict preemptive priority via a finite-state Markov chain. The main strategy of the CL scheme is to design a Markov model by explicitly including adaptive modulation and coding at the physical layer, queuing at the data link layer, and the bursty nature of multimedia traffic classes at the application layer. Utilizing this Markov model, several important performance metrics in terms of packet loss rate, delay, and throughput are examined. In addition, our proposed framework is exploited in various multimedia applications, for example, the end-to-end real-time video streaming and CL optimization, which require the priority-based QoS adaptation for different applications. More importantly, the CL framework reveals important guidelines as to optimize the network performance.

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  • 236. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Zepernick, Hans-Jürgen
    Gustavsson, Anders
    Experimental Results on Moving Targets Focusing in UWB Low Frequency SAR2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main objective of this paper is to present and evaluate a method to detect moving targets in Ultra Wideband (UWB) low frequency Synthetic Aperture Radar (SAR). Moving target detection at low radar frequencies is associated with long integration time and has to handle azimuth focusing for reliable detection. The examined method tests different hypotheses on relative speeds in the area of interest. The optimum step size between the hypotheses is found from a point target approximation. Experimental results show that the ability to detect moving targets increases significantly. In this study, the improvement of the Signal-to-Clutter Noise Ratio (SCNR) is up to approximately 20dB using a single antenna. The focusing method allows initial estimates in speed of moving targets. The SAR data, which is used in our experiments, was collected by the airborne UWB low frequency CARABAS-II system.

  • 237. Wang, Feng
    et al.
    Zepernick, Hans-Jürgen
    Autocorrelation Analysis for Reduced-Reference Mobile Video Quality Assessment2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to the growing use of mobile video services, monitoring of perceived video quality in live systems becomes of high interest. For this purpose, it is required to capture video quality consistent with the principles behind the operation of the human visual system and to accommodate some suitable quality reference to the transmission of the mobile video service. This can be achieved by extracting structural information in terms of a finite number of spatial features from a video sequence and utilize these features as foundation of a reduced-reference design of a perceptual video quality metric. In this paper, we examine the dynamics of such spatial features with respect to their progression over time by applying an autocorrelation analysis that reveals the coherence time over which the individual features can be considered as constant. As prerequisite of the analysis, we have conducted subjective tests to categorize a set of standard videos into the classes of slow, median, and fast motion. The coherence times deduced from the autocorrelation analysis show that the dynamic behavior of certain spatial features is independent from the video content while statistics of other spatial features are dependent on the video categories. These findings allow us to reduce not only the computational load for capturing dynamics of spatial features in video sequences at the mobile device but also the amount of information to be carried as reduced-reference to the receiver.

  • 238. Wang, Feng
    et al.
    Zepernick, Hans-Jürgen
    Autocorrelation Analysis of Spatial Features for Mobile Video Services2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    The growing deployment of mobile video applications is calling for new methods to measure quality as perceived by humans. The suitable quality metrics may explore spatial and temporal video features that quantify the presence of related artifacts in an examined mobile video service. Considering a video as a sequence of images, computation of spatial features for each involved image would pose significant strain on system resources such as battery power and potentially induce large computational load in the mobile terminal. In this paper, we therefore examine the progression of spatial features in mobile videos over time using an autocorrelation approach. This enables us to reveal the duration over which spatial feature values of a mobile video may be considered as constant. In analogy to the characterization of mobile radio channels, we refer to this duration as the coherence time of an examined spatial feature for a given video. The provided numerical results illustrate that large reductions in the frequency of computing spatial features in mobile videos may be obtained. This in turn reduces the consumption of resources in the mobile terminal.

  • 239. Yatawara, Yeshan
    et al.
    Caldera, Manora
    Kusuma, Tubagus Maulana
    Zepernick, Hans-Jürgen
    Unequal Error Protection for ROI Coded Images over Fading Channels2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Region of interest (ROI) coding is a feature supported by the Joint Photographic Experts Group 2000 (JPEG2000) image compression standard and allows particular regions of interest within an image to be compressed at a higher quality than the rest of the image. In this paper, unequal error protection (UEP) is proposed for ROI coded JPEG2000 images as a technique for providing increased resilience against the effects of transmission errors over a wireless communications channel. The hierarchical nature of an ROI coded JPEG2000 code-stream lends itself to the use of UEP whereby the important bits of the code-stream are protected with a strong code while the less important bits are protected with a weaker code. Simulation results obtained using symbol-by-symbol maximum a posteriori probability (MAP) decoding demonstrate that the use of UEP offers significant gains in terms of the peak signal to noise ratio (PSNR) and the percentage of readable files. Moreover, the use of ROI-based UEP leads to reduced computational complexity at the receiver.

  • 240.
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier. Blekinge Inst Technol, SE-37179 Karlskrona, Sweden..
    Toward Immersive Mobile Multimedia: Opportunities, Challenges, and Enablers2018Ingår i: 2018 12TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS) / [ed] Wysocki, TA Wysocki, BJ, IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In recent years, we have seen an increasing interest in immersive mobile multimedia applications and services. Advanced human-machine interfaces (HMIs) and related head-mounted displays (HMDs) support different levels of computer-generated virtual worlds. These worlds include mobile virtual reality (VR), mobile augmented reality (VR), and mobile mixed reality (MR) which are jointly captured under the term mobile extended reality (XR). In addition, the development of fifth generation (5G) mobile networks aims at catering for ultra-reliable low-latency communications such as mobile XR and the tactile Internet. In this context, 5G mobile networks are essential enablers to carry mobile XR beyond video gaming to the general consumer and industry markets. In this keynote lecture, the fundamentals of interconnected immersive mobile multimedia are reviewed, and opportunities, challenges, and enablers are discussed. An overview of immersive mobile multimedia from mobile video to mobile 360-degree video, mobile VR, mobile AR, mobile MR, and mobile XR is provided. Major components of interconnected immersive mobile multimedia will be discussed and application opportunities in different vertical industries are pointed out. Furthermore, challenges associated with the delivery of immersive mobile XR applications are shown through service integrity parameters. Several enablers for interconnected immersive mobile multimedia applications are highlighted including standardization activities.

  • 241.
    Zepernick, Hans-Juergen
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Descriptive Statistical Analysis of Subjective Experiments in Mobile Imaging2017Ingår i: 11th International Conference on Signal Processing and Communication Systems, ICSPCS 2017 / [ed] Wysocki, TA Wysocki, BJ, IEEE , 2017Konferensbidrag (Refereegranskat)
    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.

  • 242.
    Zepernick, Hans-Juergen
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Elwardy, Majed
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Hu, Yan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Sundstedt, Veronica
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    On the Number of Participants Needed for Subjective Quality Assessment of 360° Videos2019Ingår i: 13th International Conference on Signal Processing and Communication Systems, ICSPCS 2019 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Immersive multimedia applications such as 360° videos and virtual reality (VR) live broadcasting are expected to receive increased popularity in the consumer markets. These applications provide three-dimensional spatial information and require to develop the related advanced wired and wireless ecosystems ranging from head-mounted displays (HMDs) and processors to network connectivity. To develop immersive multimedia systems that provide acceptable user experiences, it is essential to conduct subjective experiments that support assessing subjective video quality as perceived by the users. In this paper, we focus on the question of how many participants are needed in subjective experiments for 360° videos such that a statistically meaningful subjective quality assessment is supported. For this purpose, a subjective experiment for 360° videos has been conducted using the modified absolute category rating with hidden reference (M-ACR-HR) method. A statistical analysis of the opinion scores given by the participants to the visual stimuli shown on an HMD is provided. In particular, mean opinion scores (MOS), differential MOS (DMOS), and the associated margin of error (MoE) and differential MoE are obtained. It is shown that 21 to 26 participants would be sufficient to drive the differential MoE of the DMOS below the given thresholds of ϵ =1% and ϵ=0.75%, respectively. © 2019 IEEE.

  • 243.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Quality of Mobile Multimedia Experience: Past, Present and Future2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The rapid evolution of wireless networks is driven by the growth of wireless packet data applications such as interactive mobile multimedia applications, wireless streaming services, and video-on-demand. The largely heterogeneous network structures, severe channel impairments, and complex traffic patterns make the wireless networks much more unpredictable compared to their wired counterparts. One of the major challenges with the roll-out of these services is therefore the design of wireless networks that fulfill the stringent quality of service requirements of mobile multimedia applications. In this tutorial, we provide a survey on the evolution of quality of experience (QoE) concepts in the context of mobile multimedia systems touching on the past, present, and future aspects. Specifically, the ideas behind QoE are discussed and an overview of related standardization work and major research initiatives is provided. On this basis, QoE metrics for speech, image, and video are described. Given the increase on visual services, perceptual image and video quality metrics for real-time quality assessment of mobile multimedia experience are discussed. This includes a classification of quality assessment methods, comparison of psychophysical versus engineering approaches, perceptual image and video quality assessment, and some example applications. An outlook on future work and challenges is also provided.

  • 244.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Quality of Experience Based Cross-Layer Design of Mobile Video Systems2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper introduces and discusses quality of experience based cross-layer design of mobile video systems as a means of providing technologies for jointly analyzing, adopting, and optimizing system quality. The many benefits of our novel approaches over traditional concepts will range from efficient video processing techniques over advanced real-time scheduling algorithms, to networking and service level management techniques. This will lead to better service quality and resource utilization in mobile video systems.

  • 245. Zepernick, Hans-Jürgen
    et al.
    Finger, Adolf
    Pseudo Random Signal Processing: Theory and Application2005Bok (Övrigt vetenskapligt)
  • 246. Zepernick, Hans-Jürgen
    et al.
    Finger, Adolf
    Pseudo Random Signal Processing: Theory and Application (Chinese translation edition)2007Bok (Övrigt vetenskapligt)
    Abstract [en]

    Chinese translation edition of the book ''Pseudo Random Signal Processing: Theory and Application'' by Hans -Jürgen Zepernick and Adolf Finger, John Wiley & Sons, 2005.

  • 247.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Iqbal, Muhammad Imran
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Khatibi, Siamak
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Quality of Experience of Digital Multimedia Broadcasting Services: An Experimental Study2016Ingår i: 2016 IEEE Sixth International Conference on Communications and Electronics (ICCE), IEEE, 2016, s. 437-442Konferensbidrag (Refereegranskat)
    Abstract [en]

    Digital multimedia broadcasting (DMB), also know as mobile TV, has been developed as a digital radio transmission technology that supports multimedia services such as TV, radio and datacasting. Especially, the terrestrial version of DMB, referred to as T-DMB, has been widely deployed in South Korea to deliver multimedia services to mobile devices ranging from smartphones to laptops, car navigation systems, and telematic devices for automotives. Although T-DMB is claimed to theoretically work without difficulties in vehicles with speeds up to 300 km/h, in practice, occasional skips and other temporal and spatial artifacts have been observed. In this paper, we provide an experimental study of the Quality of Experience (QoE) of T-DMB with focus on TV services. The study is based on a measurement campaign that was conducted in a live T-DMB system in South Korea consisting of TV broadcasters and DMB receivers in vehicles. In particular, a comprehensive subjective test has been conducted on the DMB test material that was obtained in the measurement campaign. A statistical analysis of the user ratings obtained from the subjective tests is reported to quantify the QoE of T-DMB in terms of mean opinion scores (MOSs) and higher order statistics. The obtained results may be used to develop related QoE models for this type of systems and services. In particular, the results may suggest to exploit insights obtained from higher order statistics such as skewness and kurtosis into QoE modeling rather than considering only MOS and variance.

  • 248. Östlin, Erik
    et al.
    Suzuki, Hajime
    Zepernick, Hans-Jürgen
    Comparisons and Evaluation of ITU-R Recomendation P.1546 Versions2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the validity of P.1546, in short range (typically less than 20km) terrestrial environment is analysed by comparing its three versions (P.1546, P.1546-1, and P.1546-2) against simple models and against measurement results obtained by utilising the pilot signal of a commercial CDMA mobile network in rural Australia. The results show that the latest version on average underestimates the field strength by more than 10 dB for typical Australian rural areas, however it improves the error standard deviation. The causes of these effects and the suggestions for further development of the Recommendation are discussed.

  • 249. Östlin, Erik
    et al.
    Suzuki, Hajime
    Zepernick, Hans-Jürgen
    Evaluation of the propagation model Recommendation ITU-R P. 1546 for mobile services in rural Australia2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the validity of Recommendation ITU-R P.1546 in a short-range terrestrial environment is analyzed. Its three versions (P.1546, P.1546-1, and P.1546-2) are compared against simple models and evaluated using measurement results that were obtained by utilizing the pilot signal of a commercial code-division multiple-access mobile telephone network. Measurement results show that P.1546-2, on average, underestimates the field strength by more than 10 dB for typical Australian rural areas. However, it improves the error standard deviation compared to previous versions. The causes of these effects and the suggestions for further development of the Recommendation are discussed and evaluated.

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