Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in /home1/dgapscom/public_html/digital_solutions/dguni/data-config.php on line 6
Journal and Conference Publications
Selected Publications:

 

Team Fitness Monitoring for Field Hockey Using In-vivo Sensor and Multiple Sinks

Sana Akram, Aamir Habib
Journal Paper Published by: Journal of Space Technology, Volume: 4, Issue: 1, Date: 19 Jun 14, Page: 39-43

Abstract

In any sport, where many players work as team, the fitness level of every single player directly affects the overall performance of the team. Beside injuries and many other game related illnesses, the most problematic thing that players usually suffer from is the muscle fatigue. Scientists are sure that the level of fatigue in an over worked muscle can be measured by measuring PH value of the blood. This is because an overburdened muscle has slightly acidic PH value than normal. This acidity is due to the production of excess lactic acid in the blood. In this research work we use in-vivo sensors to measure fatigue in field hockey players and then transmit that information to health officials of the hockey team using Wireless Body Area Network (WBAN). WBAN in our proposed design consists of multiple sinks mounted around the ground.

Efficient Data Routing with Minimum Energy Consumption to Monitor Biological Factors in Wireless Body Area Sensor Networks

Anum Tauqir, Aamir Habib
Journal Paper Published by: Journal of Space Technology, Volume: 4, Issue: 1, Date: 19 Jun 14, Page: 32-38

Abstract

The field of Wireless Body Area Sensor Networks (WBASNs) is growing very rapidly with an aim to get the real time and precise data without human intervention. These networks are being designed under low energy factors, equipped by miniaturized and lightweight sensors. These sensors are accountable to monitor different physical, chemical, natural, etc. attributes. In this research, a technique is presented to provide a WBAN in old homes. Such technique is based on a protocol, that will be able to monitor old people via sensors, sensing different chronic levels of the biological factors. Experimental results depict reduced level of energy consumption and extended network lifetime. It is also compared with a BAN protocol of Mobility-supporting Adaptive Threshold-based Thermal-aware Energy-efficient Multi-hop ProTocol (M-ATTEMPT). The research is also extended towards provision of recharging technique for the deployed sensors.

Semi Round Robin Pairing and Scheduling in Uplink Virtual Multiple Input Multiple Output (VMIMO) communications

M. Qadeer Khan, Sajid Bashir, Aamir Habib
Journal Paper Published by: Journal of Space Technology, Volume: 4, Issue: 1, Date: 19 Jun 14, Page: 61-66

Abstract

This paper considers the Semi Round Robin Scheduling (SRRS) tactics that relates different pairing norms to select a pair of users carrying out transmission simultaneously in uplink Virtual Multiple Input Multiple Output (VMIMO) system for Long Term Evolution (LTE). Five different procedures are defined and matched, which are regarded as capacity maximization and complexity reduction. The system throughput and user fairness are analyzed and simulated. As results show SRRS scheme gives a tradeoff between the throughput and fairness in Single User VMIMO (SU-VMIMO) and Multiple User VMIMO (MU-VMIMO). VMIMO with SRRS approach will remarkably improve the system throughput and can achieve the fairness up to 99%.

Optimal Decoders for 4G LTE Communication

Syed Ali Irtaza, Aamir Habib, and Qamar-ul-Islam
Journal Paper Published by: Lecture Notes on Information Theory/Engineering and Technology Publishing, Volume: 1, Issue: 4, Date: 13 Dec 13, Page: 170-174

Abstract

Multiple Input Multiple Output (MIMO) techniques are used to realize practical high data rate systems which laid the foundation of Long Term Evolution (LTE). Various transmission techniques like Transmit Diversity (TxD), Open Loop Spatial Multiplexing (OLSM) and Closed Loop Spatial Multiplexing (CLSM) are deployed in the realm of MIMO. The spectral efficiency is improved with the help Orthogonal Frequency Division Multiplexing (OFDM). In this paper we will focus on CLSM, to evaluate its performance with the help of Zero Forcing (ZF), Minimum Mean Sqaure Error (MMSE), SoftSphere Decoder (SSD), SSD K-Best (SSDKB) and SIC receivers to find the optimal decoder in LTE environment. The SSD, SSD-KB and SIC uses MMSE based equalizers. The channel environment used are Additive White Gaussian (AWGN), Vehicular A (VehA), Vehicular B (VehB) and an outdoor Pedestrian (Ped B) channel model. A Least Square (LS) estimated feedback obtained by the averaging of two channel instances is used to improve BLER in the case of fading channels.

Optimal Decoders for 4G LTE Communication

Syed Ali Irtaza, Aamir Habib, and Qamar-ul-Islam
Refereed Conference Published By: Proceedings of 2013 3rd International Conference on Communication and Management (ICICM2013) , Date: 12 Oct 13, , Pages: 1-5

Abstract

Multiple Input Multiple Output (MIMO) techniques are used to realize practical high data rate systems which laid the foundation of Long Term Evolution (LTE). Various transmission techniques like Transmit Diversity (TxD), Open Loop Spatial Multiplexing (OLSM) and Closed Loop Spatial Multiplexing (CLSM) are deployed in the realm of MIMO. The spectral efficiency is improved with the help Orthogonal Frequency Division Multiplexing (OFDM). In this paper we will focus on CLSM, to evaluate its performance with the help of Zero Forcing (ZF), Minimum Mean Sqaure Error (MMMSE), SoftSphere Decoder (SSD), SSD K-Best (SSDKB) and SIC receivers to find the optimal decoder in LTE environment. The SSD, SSD-KB and SIC uses MMSE based equalizers. The channel environment used are Additive White Gaussian (AWGN), Vehicular A (VehA), Vehicular B (VehB) and an outdoor Pedestrian (Ped B) channel model. A Least Square (LS) estimated feedback obtained by the averaging of two channel instances is used to improve BLER in the case of fading channels.

Selection Schemes for Orthogonal Tripole Antennas

Aamir Habib, Jesus Gutierrez
Refereed Conference Published By: Proceedings of 2013 International Conference on Aerospace Science & Engineering (ICASE),/IEEE, Date: 21 Aug 13, , Pages: 1-4

Abstract

Cross-polarized antenna selection schemes lead to a
considerable decrease in overall cost of system and size of the
hardware without sacrificing the advantages of multiple-input
multiple-output systems. In this work, we present a study of
receive antenna selection based on measurements obtained with a
tripole antenna pair. From the measurement data we extract the
selection gains associated with triple polarized channels for a
different number of antenna combinations at the receiver. The
obtained results show the effectiveness of dealing with antenna
selection schemes along with orthogonal antennas, providing
higher gains in most of the cases.

MIMO Channel Modeling for Integrated High Altitude Platforms, Geostationary Satellite/Land Mobile Satellite and Wireless Terrestrial Networks

Aamir Habib and Qamar-ul-Islam
Journal Paper Published by: Journal of Space Technology, Volume: 3, Issue: 1, Date: 17 Jul 13, Page: 19-26

Abstract

Abstract—In this work we analyze first the channel models associated with an integrated High Altitude Platform (HAP),  satellite and terrestrial networks and then apply multiple antenna systems to evaluate and investigate the gains that can be achieved by using MIMO techniques on such networks. We first take into account scenarios consisting of GEO satellite and few HAPs and then LMS with HAPs and construct a MIMO channel model. Subsequent to the application of such multiple antenna techniques we find the parameters that are most critical in system design and evaluate the performance advantages of such systems over conventional integrated Satellite and terrestrial only networks.

Performance of Spatial Multiplexing and Transmit Diversity in Multi-Polarized MIMO Transmissions with Receive Antenna Selection

Aamir Habib
Refereed Conference Published By: Proceedings of ICET, Date: 17 Jul 13, , Pages: 1-7

Abstract

In this work, we consider the use of multiple antenna signaling technologies, specifically space-time block coding (STBC) and spatial multiplexing (SM) schemes, in multiple-input multiple-output (MIMO) communication systems employing dual polarized antennas at both ends. The use of dual-polarized antennas theoretically double the number of virtual antennas used in the system. On the other hand, the correlation effects and the cross-polar discrimination (XPD) deteriorates the system performance. In our work, we consider these effects and present model of a 3X 3 system with triple-polarized antennas for both STBC and SM cases. We also present simulation results for both multi-antenna signaling techniques together with hybrid approaches under various XPD and correlation scenarios. The simulation results show a significant performance gain by joint utilization of space, time and polarization diversity in comparison to uni-polarized systems with the same number of antennas. We observed that dual and triple polarized systems have different performances at various channel scenarios. Antenna selection performs better for systems with space time coding and boosts the performance more in triple-polarized MIMO compared to its dual-polarized counterpart.

Receive antenna selection in diversely polarized MIMO transmissions with convex optimization

Aamir Habib
Journal Paper Published by: Physical Communication/Elsevier, Volume: 5, Issue: 4, Date: 09 Dec 12, Page: 328-337

Abstract

In this paper, we present a low complexity approach to receive antenna selection for capacity maximization, based on the theory of convex optimization. By relaxing the antenna selection variables from discrete to continuous, we arrive at a convex optimization problem. We show via extensive Monte-Carlo simulations that the proposed algorithm provides performance very close to that of the optimal selection based on an exhaustive search. We consecutively optimize not only the selection of the best antennas but also the angular orientation of individual antenna elements in the array for a so-called true polarization diversity system. Dual- and triple-polarized antenna structures are a very good solution for realizing compact devices and also robust against many imperfections as compared to spatially separated antenna structures. Effectively we extend our work from two dimensional antenna structures to three dimensions. We model such polarized antenna systems and then apply convex optimization theory for selecting the best possible antennas in terms of capacity maximization. Channel parameters like transmit and receive correlations, and cross-polarization discrimination (XPD) are taken into consideration while modeling polarized systems. We compare our results with the Spatially Separated (SP) MIMO with and without selection by performing extensive Monte Carlo simulations. We found that by using a convex optimization algorithm, the performance of multiple polarized systems can be significantly enhanced. For certain channel conditions we observe that triple polarized systems increase the performance significantly compared to dual-polarized and spatially separated systems. We observed that applying selection at the receiver only boosts the performance in Non-Line of Sight (NLOS) channels compared to Line of Sight (LOS) channels.

Indoor measurements by dual tripole antennas

Jesus Gutierrez, Aamir Habib and Markus Rupp
Refereed Conference Published By: Proceedings of 2012 Loughborough Antennas and Propagation Conference (LAPC)/ IEEE, Date: 12 Nov 12, , Pages: 1-5

Abstract

We present in this paper indoor measurements at 2.45 GHz of a tripole antenna pair and investigate typical channel characteristics that include the antenna elements. Each of the two antenna arrays consists of three orthogonal co-located dipoles promising high capacity, irrelevant of their orientation. The impact of classic parameters related to polarization, correlation and time dispersion are analyzed in order to get an idea of the performance that this real multiple-input multiple-output (MIMO) system could offer.

Antenna selection in polarized multiple input multiple output transmissions with mutual coupling

Aamir Habib, Markus Rupp
Journal Paper Published by: Integrated Computer-Aided Engineering/IOS Press, Volume: 193, Issue: , Date: 02 Jul 12, Page: 299-312

Abstract

Physical size limitations in user equipment forces multiple antennas to be spaced closely, generating a considerable amount of mutual coupling between antenna elements that cannot be neglected. Thus, the design and deployment of antenna selection schemes appropriate for next generation wireless standards such as 3GPP LTE and LTE advanced need to take these practical implementation issues into account. In this paper, we consider multiple-input multiple-output systems where antenna elements are closely placed side by side, and examine the performance of a typical antenna selection strategy in such systems under various scenarios of antenna spacing and mutual coupling with varying antenna elements. We compare a linear array with an NSpoke co-located antenna structure which comprises of antennas separated by an angular displacement rather that spatial. We further improve the performance of such systems by a new selection approach which terminates the non-selected antenna elements with a short circuit. We observe that this methodology, can improve the performance considerably. We present analytical bounds for capacity with receive antenna selection. We found that NSpoke structures perform even better than full complexity systems when used with intelligent receive antenna selection methods, with few number of antennas even in the presence of strong mutual coupling effects.

Performance Comparison of LTE Transmission Modes in High Speed Channels using Soft Sphere Decoder

Syed Ali Irtaza, Aamir Habib, and Qamar-ul-Islam
Journal Paper Published by: International Journal of Engineering & Technology IJET-IJENS, Volume: 12, Issue: 3, Date: 18 Jun 12, Page: 73-77

Abstract

Recent technologies have made real-time high data rate communication a reality. Long Term Evolution (LTE) is one of them. In this paper we discuss the performance of Transmit Diversity (TxD) and Spatial multiplexing (SM) using Multiple Input Multiple Output (MIMO) communication in comparison with Single Input Single Output (SISO) communication to achieve high data rates in LTE communication. Vehicular A (VehA) and Vehicular B (VehB) tapped delay channel model are used to model the high speed outdoor movements of the LTE user. Soft Sphere Decoder (SSD) with Minimum Mean Square Error (MMSE) equalization is used. Sphere decoder (SD) gives a sub optimal Maximum Likelihood (ML) solution with reduced complexity. Complexity is reduced as compared to the ML decoder as the solution is chosen by considering the values that are enclosed by the radius of the sphere. Soft decisions are incorporated to have reduced error probability. The comparison is performed between transmission modes to select the mode of communication based upon the SNR and throughput to achieve optimal utilization of the resources. It is observed that at lower values of SNR, TxD performs better, giving higher throughput and reduced Block Error Rate (BLER). As the SNR values are increased beyond a certain threshold, the performance of Closed Loop Spatial Multiplexing (CLSM) and Open Loop Spatial Multiplexing (OLSM) performs better than the TxD in terms of throughput therefore making TxD not suitable for higher values of SNR. The Least Square (LS) estimation for feedback provides no improvement at high speed to compensate the rapid change of the channel behavior.

Convex optimization for receive antenna selection in multi-polarized MIMO transmissions

Aamir Habib, Bujar Krasniqi and Markus Rupp
Refereed Conference Published By: Proceedings of 19th International Conference on Systems, Signals and Image Processing (IWSSIP), 2012 / IEEE, Date: 11 Apr 12, , Pages: 269-275

Abstract

Diversity and achievable rate in wireless transmissions can be enhanced by using multiple-input multiple-output (MIMO) systems. This directly increases the overall cost due to additional Radio Frequency (RF) chains for each antenna element. The issue can be resolved with antenna selection techniques at the transmitter or the receiver by using a small number of RF chains. These RF chains are multiplexed between larger number of transmitter/receiver antenna elements. Dual and triple polarized antenna structures are a very good solution for realizing compact devices and also robust against many imperfections as compared to spatially separated antenna structures. We model such polarized antenna systems and then apply convex optimization theory for selecting the best possible antennas in terms of capacity maximization. Channel parameters like transmit and receive correlations, cross-polarization discrimination (XPD) are taken into consideration while modeling polarized systems. We compare our results with the Spatially Separated (SP) MIMO with and without selection by performing extensive Monte-Carlo simulations. We found that by using convex optimization algorithm, the performance of multiple polarized systems can be significantly enhanced. For certain channel conditions we observe that triple polarized systems increase the performance significantly compared to dual-polarized and spatially separated systems. We observed that applying selection at the receiver only boosts the performance in Non Line of sight (NLOS) channels compared to Line of Sight (LOS) channels.

Antenna Selection in Polarization Diverse MIMO Transmissions with Convex Optimization

Aamir Habib, Bujar Krasniqi and Markus Rupp
Refereed Conference Published By: Proceedings of 18th IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT), 2011/IEEE, Date: 22 Nov 11, , Pages: 1-5

Abstract

A critical factor in the deployment of multiple input multiple-output systems is the cost of multiple analog transmit/receive chains. This problem can be mitigated by antenna subset selection at the transmitter/receiver. With antenna selection, a small number of analog radio frequency chains are multiplexed between a much larger number of transmit/receive antenna elements. In this paper, we present a low complexity approach to receive antenna selection for capacity maximization, based on the theory of convex optimization. By relaxing the antenna selection variables from discrete to continuous, we arrive at a convex optimization problem. We show via extensive Monte-Carlo simulations that the proposed algorithm provides performance very close to that of optimal selection based on exhaustive search. We consecutively optimize not only the selection of the best antennas but also the angular orientation of individual antenna elements in the array for a so-called true polarization diversity system.

Multiple Polarized MIMO with Antenna Selection

Refereed Conference Published By: Proceedings of 18th IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT), 2011, Ghent; 11/2011 , Date: 22 Nov 11, , Pages: 1-8

Abstract

Antenna subset selection in combination with dual-polarized antennas offers a better solution for compact and low-complexity devices using higher order Multiple-Input Multiple-Output (MIMO). In this paper we provide another degree of freedom to the existing dual-polarized MIMO and analyze the performance of antenna selection for triple-polarized MIMO systems with maximum ratio combining receivers. We theoretically analyze the impact of cross-polar discrimination on the achieved antenna selection gain for both dual and triple-polarized MIMO for non line of sight channels. We proceed to derive the outage probabilities and observe that these systems achieve significant performance gains for compact configurations with only a nominal increase in complexity. We observe that at higher cross polarization discrimination and lower transmit signal to noise ratio, the outage performance for a dual-polarized system is almost the same as triple-polarized system with joint transmit/receive antenna selection. With selection at only one end of the link, the triple-polarized system performs better than dual-polarized counterpart at higher values of transmit SNRs. We also found out that the available degrees of freedom significantly increase with lower values of cross polarization discrimination.

Performance of compact antenna arrays with receive selection

Aamir Habib, Christian Mehlf¨uhrer, and Markus Rupp
Refereed Conference Published By: Proceedings of Wireless Advanced (WiAd), 2011 , Date: 20 Jun 11, , Pages: 207-212

Abstract

The objective of this paper is to evaluate the performance of dual-polarized Multiple-Input Multiple-Output (MIMO) systems, compact in antenna array size and with reduced radio frequency complexity. We compare co-located antenna array structures with their spatial counterpart while deploying receive antenna selection. To this purpose, the performance in terms of MIMO maximum mutual information is presented. A simple norm based on instantaneous channels selects the best antennas. We derive explicit numerical expressions for the effective channel gains. These expressions are precise for small values of NS and NR, and approximately valid for higher values of NS and NR, NS and NR being the number of selected and total receive antennas, respectively. Further a comparison in terms of power imbalance between antenna elements is presented. We conclude that angularly separated compact antenna arrays with a few simple monopoles, if used with antenna selection can provide a better performance compared to a conventional Uniform Linear Array (ULA). We also show that co-located structures are robust to power imbalance and orientation variations compared to a ULA.

Receive Antenna Selection for Polarized Antennas

Aamir Habib, Christian Mehlf¨uhrer, and Markus Rupp
Refereed Conference Published By: Proceeding of 18th International Conference on Systems, Signals and Image Processing (IWSSIP), 2011 , Date: 16 Jun 11, , Pages: 1-6

Abstract

In this work we analyze the combined effects of array orientation/rotation and antenna cross polarization discrimination on the performance of dual-polarized systems with receive antenna selection. We start our analysis with a 1 out of N selection and extend it to M out of N receive antenna selection, for which we derive numerical expressions for the effective channel gains. These expressions are valid for small values of M and N, and approximately valid for higher values of M and N. Our analysis shows that robustness against rotation increases as the number of selected antennas is increased. We conclude from our analysis that M needing to be at least 1/2 of N, the maximum effective channel gain can be attained.

Performance Comparison of Antenna Selection Algorithms in WiMAX with Link Adaptation

Aamir Habib, Christian Mehlf¨uhrer, and Markus Rupp
Refereed Conference Published By: Proceedings of 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2009. CROWNCOM \'09. , Date: 22 Jun 09, , Pages: 1-5

Abstract

Antenna subset selection methods are feasible to reduce the hardware complexity of multiple-input multiple-output (MIMO) systems. Numerous methods have been devised to resolve this problem. Most of these selection schemes were applied to specific system models and for frequency flat systems. In broadband systems like WiMAX (IEEE 802.16-2004), the overall channel under consideration is typically frequency selective, and flat only over the subcarrier bandwidths. In this work, receive antenna subset selection schemes are applied to a WiMAX compliant MIMO-OFDM transmission system. Simulation results in terms of average throughput and BER on an adaptive modulation and coding link are shown. Very unexpectedly we find that the optimal selection for maximum throughput, does not give the best results in terms of BER performance. We thus conclude that minimum BER is not the right choice for antenna selection. We also find through our simulations that the simple, low complex norm based selection algorithm, provides good results, close to optimal selection in frequency selective channels.