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##### Publications (10 of 36) Show all publications
Fowler, S., Baravdish, G. & Baravdish, G. (2019). Compressed Sensing of Wireless Signals for Image Tensor Reconstruction. In: IEEE Global Communications Conference: Signal Processing for Communications (Globecom2019 SPC). Paper presented at IEEE Global Communications Conference, Waikoloa, HI, USA, 9-13 December 2019.
Open this publication in new window or tab >>Compressed Sensing of Wireless Signals for Image Tensor Reconstruction
2019 (English)In: IEEE Global Communications Conference: Signal Processing for Communications (Globecom2019 SPC), 2019Conference paper, Published paper (Refereed)
##### Abstract [en]

Use of wireless signal for identification of unknown object, or technology to see-through a wall to form an image, is gaining growing interest from various fields including law enforcement and military sectors, disaster management, or even in civilian sectors such as construction sites. The great challenge in the implementation of such technology is the stochastic disturbances on wireless signal which will result in a signal with missing samples. Compressive Sensing (CS) is a powerful tool for estimating the missing samples since it can find accurate solution to largely underdetermined linear wireless signals. However, sparse models like CS can also suffer from information loss dues to stochastic lossy nature of wireless, making CS not to have accurate information for reconstruction of a signal. In this paper, we developed a theoretical and experimental framework for the mapping of obstacles by reconstructing the wireless signal based on a sparse signal. We apply tensor format to perform the computations along each mode by relaxing the tensor constraints to obtain accurate results. The proposed framework demonstrates how to take 2D signals, formulate estimate signals and produce a 3D image location in a completely unknown area inside of the obstacle (wall).

##### Keywords
Compressed Sensing; Basis Pursuit; Ill-posed; Tensors; Lagrangian; Wireless Signals;Augmented-Lagrangian, Alternating Direction Method of Multipliers, Basis Pursuit, Ill-posed and Inverse Problems, ImagingAugmented-Lagrangian, Alternating Direction Method of Multipliers, Basis Pursuit, Ill-posed and Inverse Problems, Imaging
##### National Category
Engineering and Technology Signal Processing
##### Identifiers
urn:nbn:se:liu:diva-163576 (URN)
##### Conference
IEEE Global Communications Conference, Waikoloa, HI, USA, 9-13 December 2019
Available from: 2020-02-14 Created: 2020-02-14 Last updated: 2020-02-17Bibliographically approved
Zhang, X., Zhang, X., Fu, Z., Yu, B. & Fowler, S. (2019). Joint Distortion Estimation and Layer Selection of Unequal Error Protection for SVC Video Transmission over FSO Networks. In: 2019 IEEE 21st International Conference on High Performance Computing and Communications; IEEE 17th International Conference on Smart City; IEEE 5th International Conference on Data Science and Systems (HPCC/SmartCity/DSS): . Paper presented at 2019 IEEE 21st International Conference on High Performance Computing and Communications; IEEE 17th International Conference on Smart City; IEEE 5th International Conference on Data Science and Systems (HPCC/SmartCity/DSS) (pp. 726-733). Piscataway, New Jersey, US
Open this publication in new window or tab >>Joint Distortion Estimation and Layer Selection of Unequal Error Protection for SVC Video Transmission over FSO Networks
2019 (English)In: 2019 IEEE 21st International Conference on High Performance Computing and Communications; IEEE 17th International Conference on Smart City; IEEE 5th International Conference on Data Science and Systems (HPCC/SmartCity/DSS), Piscataway, New Jersey, US, 2019, p. 726-733Conference paper, Published paper (Refereed)
##### Abstract [en]

To meet the needs of high throughput, low delay and high resolution video services, the free space optical network (FSO) has recently received increasing attention due to its large bandwidth and high transmission rate. However, atmospheric turbulence is a major challenge, which can lead to severe BER performance degradation or even make the link ineffective. To mitigate the significant degradation of the video streaming quality on FSO networks, in this paper, an unequal error protection (UEP) scheme for scalable video coding is designed to minimize the video distortion. By adaptively choosing the number of video layers and the redundancy rate of the channel coding, unequal error protection of Scalable video coding is achieved. In addition, to solve the optimization model, a heuristic-based fast algorithm is proposed. A large number of simulation experiments in an NS3 network simulator show that the proposed scheme offers significantly higher quality in the reconstructed video sequences.

##### Place, publisher, year, edition, pages
Piscataway, New Jersey, US: , 2019
##### Keywords
channel coding;error statistics;free-space optical communication;image sequences;optical links;optimisation;redundancy;video coding;video streaming;FSO networks;unequal error protection scheme;scalable video coding;video distortion;video layers;redundancy rate;channel coding;NS3 network simulator show;reconstructed video sequences;layer selection;SVC video transmission;low delay;high resolution video services;free space optical network;high transmission rate;atmospheric turbulence;link ineffective;video streaming quality;BER performance degradation;Streaming media;Forward error correction;Error correction codes;Redundancy;Distortion;Video coding;Packet loss;Free space optical network;Forward error correction;Unequal error protection (UEP);Scalable video coding
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:liu:diva-162721 (URN)10.1109/HPCC/SmartCity/DSS.2019.00108 (DOI)
##### Conference
2019 IEEE 21st International Conference on High Performance Computing and Communications; IEEE 17th International Conference on Smart City; IEEE 5th International Conference on Data Science and Systems (HPCC/SmartCity/DSS)
Available from: 2019-12-17 Created: 2019-12-17 Last updated: 2020-01-24Bibliographically approved
Fowler, S., Baravdish, G. & Rudberg, M. (2019). Optimizing Compressed Sensing for seeing through walls based on Wireless Signals. In: IEEE Symposium on Computers and Communications (ISCC): . Paper presented at IEEE Symposium on Computers and Communications (ISCC), Barcelona, Spain, 29 June-3 July 2019 (pp. 1-6).
Open this publication in new window or tab >>Optimizing Compressed Sensing for seeing through walls based on Wireless Signals
2019 (English)In: IEEE Symposium on Computers and Communications (ISCC), 2019, p. 1-6Conference paper, Published paper (Refereed)
##### Abstract [en]

In this paper, we developed a theoretical and experimental framework for the mapping of obstacles using WiFi, based on a small number of wireless channel samples. This is very challenging due to the numerous channel coefficients to be estimated over the time-varying channel and the channel estimation of a wireless signal transmission to be considered for compressive sampling. In a typical communication system, the signal is sampled at least twice at the highest frequency contained in the signal. However, this limits efficient ways to compress the signal, as it places a huge burden on sampling the entire signal while only a small number of the transform coefficients are needed to represent the signal. To tackle this problem, we will focused on a mathematical optimization problem for the most efficient compressed sensing method called $\ell_1$-norm, known as Basis Pursuit. Before optimizing the problem, the noise was removed from the signal, namely, multipath fading. Our experimental results show the improved performance in the number of iterations for obtaining a framework for the mapping of obstacles.

##### Keywords
Compressed Sensing; Imaging; Signal Reconstruction; Basis Pursuit; Radio Tomographic; Digital Image Reconstruction
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:liu:diva-163563 (URN)10.1109/ISCC47284.2019.8969738 (DOI)
##### Conference
IEEE Symposium on Computers and Communications (ISCC), Barcelona, Spain, 29 June-3 July 2019
Available from: 2020-02-14 Created: 2020-02-14 Last updated: 2020-02-17Bibliographically approved
Al Haji, G., Fowler, S. & Andersson Granberg, T. (2018). Smart traffic calming measures for smart cities - a pre-study. Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Smart traffic calming measures for smart cities - a pre-study
##### Abstract [en]

Traffic calming measures, such as speed bumps and elevated crossing points, are used to reduce speed, to prevent overtaking and generally contribute to a safer traffic situation. However, they might also cause increased response times for rescue vehicles (e.g. ambulances or fire trucks). An alternative to the conventional traffic calming measures is so-called smart traffic calming measures. These can determine when a vehicle approaches, whose journey should not be hindered, and adjust to allow for free passage for this vehicle.

This report gives an overview of the problem, and some examples of smart  traffic calming measures are discussed. Special focus is put on the wireless communication necessary to detect emergency vehicles. Furthermore, existing challenges and possible solutions for traffic calming measures and the communication needed to make them smart are discussed.

##### Abstract [sv]

Trafiklugnande åtgärder, såsom vägbulor och förhöjda övergångsställen, används för att minska hastigheten, hindra farliga omkörningar och generellt bidra till en säkrare trafiksituation. Dock kan de också bidra till att insatstiderna för räddningsfordon (t.ex. ambulanser eller räddningstjänstens släckbilar) förlängs. Ett alternativ till de konventionella trafiklugnande åtgärderna, är s.k. smarta trafiklugnade åtgärder. Dessa kan avgöra när ett fordon närmar sig, vars färd inte bör hindras, och anpassa sig så att fri färd för detta fordon tillåts.

I denna rapport ges en översikt av problemet, och några exempel på smarta trafiklugnade åtgärder diskuteras, med fokus på sådana som hämtar information och styrs med hjälp av trådlös kommunikation. Vidare diskuteras existerande utmaningar och möjliga lösningar för trafiklugnande åtgärder och den kommunikation som krävs för att göra dem smarta.

##### Series
CARER Report ; 22
##### National Category
Transport Systems and Logistics Computer Engineering Infrastructure Engineering
##### Identifiers
urn:nbn:se:liu:diva-145386 (URN)
Available from: 2018-02-27 Created: 2018-02-27 Last updated: 2018-02-27Bibliographically approved
Mushtaq, M. S., Fowler, S., Augustin, B. & Mellouk, A. (2016). QoE in 5G Cloud Networks using Multimedia Services. In: 2016 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE: . Paper presented at IEEE Wireless Communication and Networking Conference (WCNC’16). IEEE Computer Society
Open this publication in new window or tab >>QoE in 5G Cloud Networks using Multimedia Services
2016 (English)In: 2016 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, IEEE Computer Society, 2016Conference paper, Published paper (Refereed)
##### Abstract [en]

The 4G standard Long Term Evolution-Advanced(LTE-A) has been deployed in many countries. Now, technologyis evolving towards the 5G standard since it is expecting tostart its service in 2020. The 5G cellular networks will mainlycontain in cloud computing and primarily Quality of Service(QoS) parameters (e.g. delay, loss rate, etc.) influence thecloud network performance. The impact of user perceivedQuality of Experience (QoE) using multimedia services, andapplication significantly relies on the QoS parameters. The keychallenge of 5G technology is to reduce the delay less thanone millisecond. In this paper, we have described a methodthat minimizes the overall network delay for multimediaservices; which are constant bit rate (VoIP) and variablebit rate (video) traffic model. We also proposed a methodthat measures the user’s QoE for video streaming trafficusing the network QoS parameters, i.e. delay and packet lossrate. The performance of proposed QoE method is comparedwith QoV method, and our proposed QoE method performsbest by carefully handle the impact of QoS parameters. Theresults show that our described method successfully reduces theoverall network delays, which result to maximize the user’s QoE.

##### Place, publisher, year, edition, pages
IEEE Computer Society, 2016
##### Series
IEEE Wireless Communications and Networking Conference, ISSN 1525-3511
##### Keywords
QoE; QoS; 5G; Cloud; VoIP; Video; Multimedia Services.
##### National Category
Communication Systems
##### Identifiers
urn:nbn:se:liu:diva-128164 (URN)10.1109/WCNC.2016.7565173 (DOI)000388603103053 ()978-1-4673-9814-5 (ISBN)
##### Conference
IEEE Wireless Communication and Networking Conference (WCNC’16)
Available from: 2016-05-19 Created: 2016-05-19 Last updated: 2016-12-27Bibliographically approved
Mushtaq, M. S., Mellouk, A., Augustin, B. & Fowler, S. (2016). QoE Power-Efficient Multimedia Delivery Method for LTE-A. IEEE Systems Journal, 10(2), 749-760
Open this publication in new window or tab >>QoE Power-Efficient Multimedia Delivery Method for LTE-A
2016 (English)In: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 10, no 2, p. 749-760Article in journal (Refereed) Published
##### Abstract [en]

The fastest growing of multimedia services overfuture wireless communication system demand more networkresources, efficient delivery of multimedia service with highusers satisfaction, and power optimization of User Equipments(UEs). The resources and power optimization are significant infuture mobile computing systems, because emerging multimediaservices consume more resources and power. The 4G standard ofLTE-A wireless system has adopted the Discontinuous Reception(DRX) method to extend and optimize the UE battery life,while there is no standard scheduling method to distribute theradio resources among the UE. This paper presents a downlinkscheduler, i.e. Quality of Experience (QoE) Power EfficientMethod (QEPEM) for LTE-A, which efficiently allocates theradio resources and optimizes the use of UE power using theDRX mechanism. We investigates how the different durationof DRX Light and Deep Sleep cycle influences the QoS andQoE of end users, using VoIP over the LTE-A. The QEPEMis evaluated with the traditional methods, in terms of SystemThroughput, Fairness Index, Packet Loss Rate, and PacketDelay. The QEPEM measures the user’s QoE, and feedback toeNodeB for scheduling decisions along with other importantparameters. Our proposed method reduces the packet delay,packet loss, and increases the fairness and UE’s power savingwith high users satisfaction.

##### Place, publisher, year, edition, pages
IEEE Communications Society, 2016
##### Keywords
QoE; QoS; LTE; Power Saving; Scheduling; VoIP; DRX; Light Sleep; Deep Sleep; Multimedia
##### National Category
Communication Systems
##### Identifiers
urn:nbn:se:liu:diva-117941 (URN)10.1109/JSYST.2015.2435994 (DOI)000383258600033 ()
Available from: 2015-08-22 Created: 2015-05-18 Last updated: 2017-12-04Bibliographically approved
Fowler, S., Shahidullah, A. O., Osman, M., Karlsson, J. M. & Yuan, D. (2015). Analytical evaluation of extended DRX with additional active cycles for light traffic. The International Journal of Computer Networks (COMNET), Elsevier, 77, 90-102
Open this publication in new window or tab >>Analytical evaluation of extended DRX with additional active cycles for light traffic
2015 (English)In: The International Journal of Computer Networks (COMNET), Elsevier, ISSN 1389-1286, Vol. 77, p. 90-102Article in journal (Refereed) Published
##### Abstract [en]

Abstract LTE and LTE-Advanced mobile technologies have integrated discontinuous reception (DRX) power saving method to optimize the power consumption at the user equipment (UE). The DRX method was proposed by the 3rd Generation Partnership Project (3GPP), and since then, the traffic behavior has been analyzed in several studies with a standard 3-state DRX model to describe the trade-off between power saving and delay. In this paper, we presented a novel 4-state and 5-state 3GPP LTE DRX mechanisms. The proposed mechanisms were developed by augmenting (an) active state(s) to deep and/or light sleep cycle of standard 3-state DRX for handling a small burst of packets, thereby bypassing the process of returning to the timer-dependent active mode. We have generated analytical models using a semi-Markov process for bursty packet data traffic and evaluated these augmented DRX mechanisms against a standard 3-state DRX method. Overall, the analytical results from varying timing parameters showed that our augmented DRX (both 4-state and 5-state) improved power saving factor (ranging between 1% and 8%) and reduced delay (ranging between 20% and 60%) compared to the standard 3-state DRX. Furthermore, the magnitude of improvement for both delay and power-saving was somewhat greater in 5-state than 4-state.

Elsevier, 2015
##### Keywords
LTE, LTE-Advanced, DRX, Power saving, Delay, Semi-Markov process
##### National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:liu:diva-114286 (URN)10.1016/j.comnet.2014.11.020 (DOI)000349502300006 ()
##### Projects
EC-FP7 Marie Curie CIG Grant, Proposal number: 294182
##### Funder
EU, FP7, Seventh Framework Programme Available from: 2015-02-17 Created: 2015-02-17 Last updated: 2016-03-02Bibliographically approved
Fowler, S., Sarfraz, J., Abbas, M. M. & Angelakis, V. (2015). Gaussian semi-Markov Model based on Real Video Multimedia Traffic. In: IEEE (Ed.), IEEE International Conference on Communications Communications (ICC) 2015: . Paper presented at IEEE ICC 2015 - Communications Software, Services and Multimedia Applications Symposium, 8-12 June 2015, London, UK (pp. 6971-6976). IEEE Press
Open this publication in new window or tab >>Gaussian semi-Markov Model based on Real Video Multimedia Traffic
2015 (English)In: IEEE International Conference on Communications Communications (ICC) 2015 / [ed] IEEE, IEEE Press, 2015, p. 6971-6976Conference paper, Published paper (Refereed)
##### Abstract [en]

The 3rd Generation Partnership Project (3GPP) introduced the new radio access technology, LTE (Long Term Evolution) and LTE-Advanced, which has the capability to provide larger bandwidth and low latencies on a wireless network in order to fulfill the demand of Users' Equipment (UEs) with acceptable Quality of Service (QoS). One of the data-heavy applications that has exploded on the market is Video. This calls for accurate modeling of video traffic. To ensure the quality and correctness of complex systems with Video traffic, it is important to evaluate the behavior of the traffic in the heterogeneous environment. This paper presents measurements on LTE Video traffic which were performed in a real environment. We derived a semi-Markov model which accurately reproduces the statistics of composite Video measurements over LTE network.

IEEE Press, 2015
##### Series
IEEE International Conference on Communications, ISSN 1550-3607
##### Keywords
LTE; semi-Markov; lognormal; Gaussian Mixture Model; Real Video Traffic; Empirical Data
##### National Category
Telecommunications
##### Identifiers
urn:nbn:se:liu:diva-117277 (URN)10.1109/ICC.2015.7249437 (DOI)000371708107033 ()
##### Conference
IEEE ICC 2015 - Communications Software, Services and Multimedia Applications Symposium, 8-12 June 2015, London, UK
##### Projects
EC-FP7 Marie Curie CIG grant, Proposal number: 294182;European Unions Seventh Framework Programme (FP7/2007-2013) under grant agreement no [609094 RERUM].
##### Funder
EU, FP7, Seventh Framework Programme, 609094EU, FP7, Seventh Framework Programme, 294182 Available from: 2015-08-22 Created: 2015-04-22 Last updated: 2016-04-20Bibliographically approved
Bitam, S., Mellouk, A. & Fowler, S. (2015). MQBV: multicast quality of service swarm bee routing for vehicular ad hoc networks. Wireless Communications & Mobile Computing, 15(9), 1391-1404
Open this publication in new window or tab >>MQBV: multicast quality of service swarm bee routing for vehicular ad hoc networks
2015 (English)In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, no 9, p. 1391-1404Article in journal (Refereed) Published
##### Abstract [en]

Vehicular ad hoc networks (VANETs) are witnessing in recent years a rapid development for road transmissions and are considered as one of the most important types of next generation networks, in which drivers can have access anywhere and anytime to information. However, vehicles have to deal with many challenges such as the links failures due to their frequent mobility as well as limited degrees of freedom in their mobility patterns. In this paper, we propose a new quality of service multicast and multipath routing protocol for VANETs, based on the paradigm of bees communication, called multicast quality of service swarm bee routing for VANETs (MQBV). The MQBV finds and maintains robust routes between the source node and all multicast group members. Therefore, the average end-to-end delay and the normalized overhead load should be reduced, while at the same time increasing the average bandwidth and the packet delivery ratio. Extensive simulation results were obtained using ns-2 simulator in a realistic VANET settings and demonstrated the efficiency of the proposed protocol. Copyright (c) 2013 John Wiley and Sons, Ltd.

##### Place, publisher, year, edition, pages
Wiley: 12 months, 2015
##### Keywords
vehicular ad hoc network; routing; bee swarm; quality of service; road safety
##### National Category
Civil Engineering
##### Identifiers
urn:nbn:se:liu:diva-120040 (URN)10.1002/wcm.2420 (DOI)000355738200008 ()
Available from: 2015-07-06 Created: 2015-07-06 Last updated: 2017-12-04
Mushtaq, M. S., Fowler, S., Augustin, B. & Mellouk, A. (2015). QoE in 5G Wireless Cellular Networks based on Mobile Cloud Network. In: : . Paper presented at IEEE INFOCOM Workshop (MMCloudCom). IEEE conference proceedings
Open this publication in new window or tab >>QoE in 5G Wireless Cellular Networks based on Mobile Cloud Network
2015 (English)Conference paper, Published paper (Refereed)
##### Abstract [en]

The 4G standard Long Term Evolution-Advanced(LTE-A) has been deployed in many countries. Now, technologyis evolving towards the 5G standard since it is expecting tostart its services in 2020. The 5G cellular networks will mainlycontain in cloud computing and primarily Quality of Service(QoS) parameters (e.g. delay, loss rate, etc.) influence the cloudnetwork performance. The impact of user perceived Quality ofExperience (QoE) significantly relies on the QoS parameters. Thekey challenge of 5G technology is to reduce the delay less thanone millisecond. In this paper, we have described a method thatminimizes the overall network delay for constant bit rate (VoIP)and variable bit rate (video) traffic model. We also proposed amethod that measures the user’s QoE for video streaming trafficusing the network QoS parameters, i.e. delay and packet lossrate. The performance of proposed QoE method is comparedwith QoV method, and our proposed QoE method performsbest by carefully handle the impact of QoS parameters. Theresults show that our described method successfully reduces theoverall network delays, which result to maximize the user’s QoE.

##### Place, publisher, year, edition, pages
IEEE conference proceedings, 2015
##### Keywords
QoE; 5G; Mobile Cloud Computing; LTE; LTE-A: QoS; Video; VoIP;Cloud
##### National Category
Communication Systems
##### Identifiers
urn:nbn:se:liu:diva-117748 (URN)
##### Conference
IEEE INFOCOM Workshop (MMCloudCom)
Available from: 2015-08-22 Created: 2015-05-08 Last updated: 2015-10-21Bibliographically approved
##### Identifiers
ORCID iD: orcid.org/0000-0002-0019-8411

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