M.O. Hasna

Qatar University, Ad Dawḩah, Ad Dawḩah, Qatar

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Publications (100)49.55 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a concise yet comprehensive description of a multichannel vehicle-to-infrastructure communication system. Existing mathematical models for such a system overlook some of its essential behavioral characteristics such as the reneging, force termination, and, ultimately, blocking of service requests (SRs). Thus, the reported performance results obtained from these models seem to be unrealistically overoptimistic. Accordingly, in this paper, a multiserver queueing model is proposed for the purpose of accurately capturing the dynamics of the aforementioned communication system and evaluating its performance. The proposed model is renowned for its complexity and the nonexistence of closed-form analytical expressions that characterize its fundamental performance metrics. Hence, approximations were exploited as a means to enhance this model's mathematical tractability. Simulations are conducted in the context of a realistic scenario with the objective of validating the proposed approximate model, verifying its accuracy, and characterizing the system's performance in terms of several new metrics. The simulations' results indicate a cataclysmic SR blocking probability in the range of 65%–85%.
    IEEE Transactions on Intelligent Transportation Systems 01/2014; 15(3):1155-1167. · 3.06 Impact Factor
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    ABSTRACT: In this paper, we consider spectrum sharing between cognitive radio (CR) users and a licensed primary user (PU) to enhance the spectrum efficiency. In the considered scenario, the PU is not able to successfully transmit data to the intended receiver. In this case, the cognitive base station (CBS) in the vicinity of the primary network offers its help to transmit the primary data. In return, the CR system shares the spectrum with the primary system. In particular, we formulate an opportunistic spectrum sharing approach that determines the optimal beamforming weights at the CBS to maximize the overall worst throughput of the CRs while guaranteeing a certain quality of service (QoS) for the PU. Various formulations of beamforming are proposed, which consider different relaying scenarios, including robust designs that are applicable with imperfect channel state information (CSI) at the PU. The original optimization problems are nonconvex and do not have any closed-form solutions. However, using a convex optimization approach, we transform them into convex forms and find approximate solutions using semidefinite programming (SDP) along with randomization techniques. We consider different examples that demonstrate the efficiency of the proposed approach.
    IEEE Transactions on Vehicular Technology 01/2014; 63(5):2224-2235. · 2.06 Impact Factor
  • A. Gouissem, R. Hamila, M.O. Hasna
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    ABSTRACT: In this contribution, we investigate the outage performance of OFDM-based Decode and Forward (DF), Amplify and Forward (AF) and Controlled DF (CDF) cooperative systems under IQ Imbalance (IQI). In particular, tractable and compact approximate outage probability expressions are derived and the effect of the different IQI parameters is analyzed for different SNR ranges. Furthermore, by localizing the error floor in terms of IQI and SNR for each technique, we demonstrate when it is more beneficial to invest in increasing the transmission power or in compensating the imbalance. Moreover, we prove that the IQI compensation should be concentrated in the relay for some techniques and in the destination for some others. A comparative study between AF, DF, CDF and direct link transmission techniques is also conducted for different IQI parameters, SNR ranges, transmission rates and relay's position. Hence, this work may create a paradigm for future studies of more effective adaptive IQI compensation techniques that concentrate the compensation on the right IQI, SNR ranges, transceivers depending on the used transmission technique.
    IEEE Transactions on Communications 01/2014; 62(5):1480-1489. · 1.75 Impact Factor
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    ABSTRACT: This paper presents a concise yet comprehensive description of a multi-channel Vehicle-to-Infrastructure (V2I) communication system. Existing mathematical models for such a system overlook some of its essential behavioural characteristics such as the reneging, force-termination and ultimately blocking of service requests. Thus, the reported performance results obtained from these models seem to be unrealistically overoptimistic. Accordingly, in this paper, a multi-server queueing model is proposed for the purpose of accurately capturing the dynamics of the above-mentioned communication system and evaluating its performance. The proposed model is renowned for its complexity and the non- existance of closed-form analytical expressions that characterize its fundamental performance metrics. Hence, approximations were exploited as a mean to enhance this model’s mathematical tractability. Simulations are conducted in the context of a realistic scenario with the objective of validating the proposed approximate model, verifying its accuracy and characterizing the system’s performance in terms of several new metrics. The simulations’ results indicate a cataclysmic service request blocking probability in the range of 65% to 85%.
    IEEE Transactions on Intelligent Transportation Systems 11/2013; PP(99):1-13. · 3.06 Impact Factor
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    ABSTRACT: Underlay cognitive networks operate simultaneously with primary networks satisfying stringent interference constraints, which reduces their transmission power and coverage area. To reach remote destinations, secondary sources use relaying techniques. Selecting the best relay among the available ones is a well known technique. Recently, selective cooperation is investigated in cognitive networks where the secondary nodes can adapt their transmission power to always satisfy the interference threshold. In this paper, we investigate a situation where the secondary nodes have a fixed transmission power and may violate the interference threshold. We present two relay selection schemes; the first one excludes the relays not satisfying the interference constraint and then picks up a relay from the remaining ones that can provide the maximum signal-to-noise ratio (SNR). The other scheme uses a quotient of the relay link SNR and the interference from the relay to the primary user and optimizes it to maximise the relay link SNR. We derive closed form expressions for outage probability, bit error rate, channel capacity and diversity of the system for both schemes by using tight approximations. We also study mutual effects of interference. Simulation results confirm the analytical results and reveal that the relay selection is feasible at low SNRs. Copyright © 2013 John Wiley & Sons, Ltd.
    Transactions on Emerging Telecommunications Technologies. 11/2013; 24(7-8).
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    ABSTRACT: In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.
    Wireless Communications and Mobile Computing 07/2013; 13(10). · 0.86 Impact Factor
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    ABSTRACT: We address in this paper the challenge of coping with asymmetric data rates in two-way relay channels. We consider a relay network comprising two sources and one relay. The sources communicate at different rates through the relay. That is, we assume that one source uses M1-QAM (quadrature amplitude modulation) and the other uses M1/M2-QAM hierarchical modulation where M1 ≠ M2. For the underlying network, we consider two decode-and-forward (DF) relaying schemes. One scheme combines hierarchical zero padding and network coding (HZPNC) at the relay. The novelty of this scheme lies in the way the two signals (that have different lengths) are network-coded at the relay. The other scheme is referred to as opportunistic user selection (OUS) where the user with a better end-to-end channel quality is given priority for transmission. We analyze both schemes where we derive closedform expressions for the end-to-end (E2E) bit error rate (BER). Since the two schemes offer a trade-off between performance and throughput, we analyze and compare both schemes in terms of channel access probability and average throughput. We show that HZPNC offers better throughput and fairness for both users, whereas OUS offers better performance. We also compare the performance of HZPNC with existing schemes including the original zero padding, nesting constellation modulation and superposition modulation. We show through examples the superiority of the proposed HZPNC scheme in terms of performance and/or reduced complexity.
    IEEE Transactions on Communications 01/2013; 61(7):2900-2910. · 1.75 Impact Factor
  • S.H. Song, M.O. Hasna, K.B. Letaief
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    ABSTRACT: Relaying primary signals by cognitive base-stations (CBSs) can help the primary system and thus win CBSs a higher chance to transmit their own signals. For this purpose, conventional zero-forcing (CZF) beamforming is a straightforward solution where the primary and cognitive signals are transmitted from a multi-antenna CBS without causing interference to each other. However, with CZF, no priority is given to the primary user (PU), which is not consistent with the idea of cognitive radio. In this paper, we shall propose a prior ZF (PZF) scheme which gives priority to the PU by transmitting primary signals without considering their interference to the cognitive users (CUs), while cognitive signals are not allowed to generate interference to the PU. As a result, PZF provides a better channel for the CBS-PU link than CZF but the same channel gain for the CBS-CU links as CZF. We compare PZF and CZF by considering both the transmit power with given target rates and the outage performance with given transmit power, where closed-form conditions are derived to indicate their respective advantages. One of the important contributions of this paper is to prove that, with one CU, a target rate of 1 bit/s/Hz for the CU is the key point that differentiates PZF and CZF, which is independent of the number of CBS-antennas, the channel distributions, and the signal-to-noise power ratio (SNR).
    IEEE Transactions on Wireless Communications 01/2013; 12(2):938-947. · 2.42 Impact Factor
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    ABSTRACT: We consider a spectrum sharing scenario between cognitive radio (CR) users and a licensed primary user (PU), in which the PU is not able to successfully transmit data to its destined receiver. The cognitive base station (CBS) in the vicinity of the primary network, offers its help to transmit the primary data. In return, the CR system is able to share the spectrum with the primary system. We formulate an opportunistic spectrum sharing approach that determines the transmit beamforming weights in order to maximize the overall throughput of the CRs while guaranteeing the quality-of-service (QoS) of the PU. By applying algorithms based on zero-forcing beamforming (ZFB) along with optimal power allocation, the proposed approach is able to achieve cognitive and primary systems requirements.
    IEEE Communications Letters 01/2013; 17(2):313-316. · 1.16 Impact Factor
  • H. Chamkhia, M.O. Hasna
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    ABSTRACT: Cognitive Radio (CR) aims to improve spectrum utilization by allowing unlicensed users to access the licensed spectrum and to coexist with primary user (PU) while respecting the PU's restrictions. An interesting case to consider in underlay CR is when the channel state informations (CSI) of the links between secondary users (SUs) or between SUs and PU are imperfect. In fact, due to feedback or scheduling delays, in practice, the relay and/or the source node can have outdated channel state information. This outdated information will cause a performance degradation. In this paper, its impact on relay selection schemes and PU are investigated. To evaluate the impact of imperfect CSI on the secondary network, closed form expressions of the bit error rate (BER), the outage probability and the ergodic capacity are derived. Additionally, we investigate how harmful imperfect CSI can be on the PU's side. The theoretical results obtained in this work are confirmed through simulations.
    ICT Convergence (ICTC), 2013 International Conference on; 01/2013
  • Hela Chamkhia, Mazen O. Hasna
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    ABSTRACT: Cognitive Radio is a promising concept that offers solution to spectral crowding problem by introducing opportunistic usage of the unoccupied licensed frequency bands. Improving the network capacity and reliability of the communication has been recently studied and this through the introduction of cooperative technology in the CR networks. Furthermore, OFDM system is considered to be a good candidate to enhance the flexibility of the CR network, where individual carriers can be switched off for occupied frequencies by the primary user (PU) or for interfering Sub-channels. In this paper, an underlay cognitive network based on OFDM technique is proposed where secondary users (SUs) coexisting with a PU are adhering to stringent interference threshold constraint. Cooperative technology will help improving the CR network performances under PU limitation. This paper proposes new Sub-channel selection schemes which adapt either the transmission power or the sequential order of selection to enhance the system performances. We first provide the exact probability density function (PDF) of the received SNR at the secondary destination. Then, the PDFs are used to derive closed form expressions of the outage probability, the average BER and the ergodic capacity. Analytic results are validated by simulation for the proposed Sub-channels selection schemes.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2013 IEEE 24th International Symposium on; 01/2013
  • H. Chamkhia, M.O. Hasna
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    ABSTRACT: Cognitive radio (CR) is a promising technology that allows wireless systems to sense the environment and learn from previous experience to improve the communication quality. However, CR needs a flexible and adaptive physical layer in order to perform the required tasks efficiently. An OFDM system is considered to be a good candidate where individual carriers can be switched off for frequencies occupied by a licensed user or interfering sub-carriers. In this paper, an underlay cognitive radio system based on OFDM technique is proposed where secondary users operating in the presence of primary user are adhering to stringent interference and threshold constraint. In order not to violate this interference limit, the underlay network will make the use of relays to transmit signals over the secondary network. This paper proposes new relay or sub-carriers selection schemes. We derive closed form expressions of the probability density function (PDF) of the SNR at the secondary destination, the outage probability, the average bit error probability and the ergodic capacity. Analytical results are validated by simulations for the different relay selection schemes proposed herein.
    Signal Processing Advances in Wireless Communications (SPAWC), 2013 IEEE 14th Workshop on; 01/2013
  • A. Omri, M.O. Hasna
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    ABSTRACT: In long term evolution (LTE) systems, the achievable cell spectral efficiency is often limited by the inter carrier interference (ICI) or coverage shortage of base stations. Hence, in LTE-Advanced, cooperative communication has been proposed as an efficient technique to extend coverage, and improve throughput and link reliability. However, its performance gain is degraded in the presence of co-channel interference. In this paper, we propose cooperative communications scheme with interference management for LTE-A systems. The proposed scheme is based on best sub-channel selection (BSS) technique. BSS maximizes the received signal to interference plus noise ratio (SINR) for each orthogonal frequency-division multiplexing (OFDM) subcarrier while keeping the interference levels below a certain threshold. The scheme is using decoding and forward (DF) relaying protocol, and maximum ratio combined (MRC) receiver to combine the direct link (DL) and selected relaying signals. We derive exact closed form expressions of outage probability, ergodic capacity, and average bit error probability for the proposed scheme. In addition, we analysis the optimal sub-channel selection period for LTE-A system under users mobility. Simulations are used to validate the analytical expressions. The results confirm the advantage of the proposed scheme in enhancing interference management and link reliability.
    ICT Convergence (ICTC), 2013 International Conference on; 01/2013
  • Young Jin Chun, Mazen O. Hasna, Ali Ghrayeb
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    ABSTRACT: We consider network coded cooperation for cognitive relay networks. The primary system comprises multiple sources and multiple destinations, whereas the secondary system comprises multiple sources, multiple relays and a single destination. We derive a closed form expression for the end-to-end outage probability for the secondary system while assuming the presence of interference constraints between the two sub-systems. Based on the diversity order analysis, we propose a framework for adaptive network coding. The proposed scheme involves using a small encoding set size for low link quality and a large encoding set for good link quality. Having a small set size increases the probability of having relay cooperation, which comes at the expense of some loss in coding gain, whereas using a large encoding set size decreases the probability of having relay cooperation, but achieves some network coding gains. Therefore, there is a fundamental trade-off between the probability of relay cooperation and the achievable network coding gains. Using numerical results, we show that the proposed adaptive network coding achieves up to 5 dB gain at target outage 10−3 as compared to conventional fixed network coding schemes.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2013 IEEE 24th International Symposium on; 01/2013
  • Lei Zhang, Hong-Chuan Yang, M.O. Hasna
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    ABSTRACT: Cognitive radio is a promising technology to improve the spectrum utilization by allowing the unlicensed (secondary) user share a frequency bandwidth with the licensed (primary) owner under the condition that no harmful interference is imposed on the licensee. In this paper, we analyze the spatial spectrum utilization efficiency of underlay cognitive radio transmission. In particular, we apply the performance metric, generalized area spectral efficiency (GASE), to the performance evaluation and design of underlay cognitive radio transmission. Closed-form expressions are given on the ergodic capacity of the primary and secondary user in underlay cognitive radio transmission over Rayleigh fading channels, which are then utilized to evaluate GASE metric. Mathematical analysis and numerical examples show the asymptotic GASE performance of the underlay cognitive radio transmission with respect to the interference constraint on the primary receiver. We show that GASE performance metric provides a new perspective to the design of underlay cognitive radio transmission.
    Wireless Communications and Networking Conference (WCNC), 2013 IEEE; 01/2013
  • A. Omri, M.O. Hasna
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    ABSTRACT: Cooperative communication is a promising technique for future wireless networks. It can be used in improving communication reliability, and enhancing power and spectrum efficiency. However, its performance gain degrades in the presence of co-channel interference which makes it essential to propose interference mitigation schemes. In this paper, we introduce two efficient cooperative communication schemes with interference management for multi-user cooperative wireless networks that are based on best relay and user selection (BRUS) technique. BRUS maximizes the received signal to noise ratio (SNR) while minimizing the interference by an optimal time slot allocation for the users. The first introduced scheme is using BRUS technique only if the user demands cooperation, and the second scheme is always using BRUS technique to enhance the system performance. We derive exact closed form expressions for the outage probability, ergodic capacity, average consumed power, and average bit error probability for the introduced cooperative schemes. Simulations are used to validate the analytical results and an agreement is observed. The results confirm the advantage of the introduced cooperation schemes in enhancing the system performance and improving the interference management.
    Communications (ICC), 2013 IEEE International Conference on; 01/2013
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    ABSTRACT: We consider a multi-carrier cooperative underwater acoustic communication (UWAC) system and investigate the Doppler scaling problem arising due to the motion of different nodes. Specifically, we assume an orthogonal frequency division multiplexing (OFDM) system with amplify and forward (AF) relaying. Our channel model is built on large-scale path loss along with the short-term frequency-selective fading. For Doppler scaling compensation, we use multi-resampling (MR) receiver designs both at the relay and destination nodes. We present an extensive Monte Carlo simulation study to evaluate the error rate performance of the proposed UWAC system. In simulations, we use the publicly available VirTEX software in conjunction with the ray-tracing based BELLHOP software to precisely reflect the characteristics of an underwater geographical location and the movement of the nodes.
    OCEANS - Bergen, 2013 MTS/IEEE; 01/2013
  • A. Gouissem, R. Hamila, M.O. Hasna
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    ABSTRACT: In the presence of different IQ imbalance (IQI) levels in the different nodes of a cooperative system, it becomes necessary to investigate the effect of each imbalance parameter on the performance. In this contribution, we investigate the outage performance of OFDM based Decode and Forward (DF) and Amplify and Forward (AF) systems over Rayleigh channels under IQI. In particular, approximate outage probability expressions are derived and the effect of different IQI parameters is analyzed for different ranges of SNR. The diversity order is also derived depending on the IQI levels. Furthermore, we explain when and where it is more beneficial to invest in compensating the imbalance or in increasing the transmission power. Based on the outage performance, a comparative study between AF, DF and direct link transmission techniques is also discussed depending on the IQI parameters, the SNR range, the transmission rate and the relays position.
    Global Information Infrastructure Symposium, 2013; 01/2013
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    ABSTRACT: Selecting the best relay using the maximum signal to noise ratio (SNR) among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. In this paper, we analyze the performance of the best relay selection scheme with fixed gain relays operating in Nakagami-mm channels. We first derive the probability density function (PDF) of upper bounded end-to-end SNR of the relay link. Using this PDF, we derive some key performance parameters for the system including average bit error probability and average channel capacity. The analytical results are verified through Monte Carlo simulations.
    Physical Communication 09/2012; 5(3):272–279.
  • Xuehua Zhang, Mazen Hasna, Ali Ghrayeb
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    ABSTRACT: In this paper, we consider two relay assignment schemes for cooperative networks comprising multiple source-destination pairs. Both schemes are based on the max-min criterion and aim at achieving the maximum spatial diversity for all pairs. One scheme is used as a performance benchmark since it considers all possible relay assignment permutations and selects the best one. The other scheme, on the other hand, considers only a subset of those permutations and selects the best one. The advantages of the latter one is that it reduces the complexity of the assignment process, in addition to making the performance analysis tractable. We examine these schemes over asymmetric channels using M-ary phase shift keying signaling. We consider both amplify-and-forward (AF) and decode-and-forward (DF) relaying where we derive expressions for the end-to-end (E2E) symbol error rate (SER). In both cases, we show that the full spatial diversity is achieved. To account for error propagation in DF relaying, we adopt a threshold-based relaying scheme whereby the relays forward only bits that are deemed reliable and remain silent otherwise. We compare this scheme to Genie-aided relaying where the relays forward only correctly decoded bits. We analyze these two schemes and derive expressions for the E2E SER performance. We present several numerical examples that validate the analytical results.
    IEEE Transactions on Wireless Communications 02/2012; · 2.42 Impact Factor

Publication Stats

2k Citations
49.55 Total Impact Points

Institutions

  • 2003–2013
    • Qatar University
      • Department of Electrical Engineering
      Ad Dawḩah, Ad Dawḩah, Qatar
  • 2011
    • University of British Columbia - Vancouver
      • Department of Electrical and Computer Engineering
      Vancouver, British Columbia, Canada
  • 2008–2011
    • Texas A&M University at Qatar
      Ad Dawḩah, Ad Dawḩah, Qatar
  • 2009–2010
    • Concordia University Montreal
      • Department of Electrical and Computer Engineering
      Montréal, Quebec, Canada
  • 2000–2005
    • University of Minnesota Twin Cities
      • Department of Electrical and Computer Engineering
      Minneapolis, MN, United States
  • 2002–2004
    • University of Minnesota Duluth
      • Department of Electrical Engineering
      Duluth, Minnesota, United States