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Mohamedslim Alouini - One of the best experts on this subject based on the ideXlab platform.

  • on the asymptotic throughput of the k th best secondary user selection in cognitive radio systems
    Vehicular Technology Conference, 2018
    Co-Authors: Yazan H Albadarneh, C N Georghiades, Mohamedslim Alouini
    Abstract:

    We analyze the asymptotic average and effective throughputs of a multiuser diversity scheme for a secondary multiuser network consisting of multiple secondary users (transmitters) and one secondary receiver. Considering a transmit power adaptation strategy at the secondary users to satisfy the instantaneous Interference Constraint at the primary receiver, the secondary receiver selects the $k$ -th best secondary user for transmission, namely, the one with the $k$ -th highest signal-to-noise ratio (SNR). We use extreme value theory to show that the $k$ -th highest SNR converges uniformly in distribution to an inverse gamma random variable for a fixed $k$ and large number of secondary users. We use this result to derive closed-form asymptotic expressions for the average and effective throughputs of the $k$ -th best secondary user.

  • transmit antenna selection for power adaptive underlay cognitive radio with instantaneous Interference Constraint
    IEEE Transactions on Communications, 2017
    Co-Authors: Muhammad Hanif, Hongchuan Yang, Mohamedslim Alouini
    Abstract:

    The high hardware cost associated with multiple antennas at the secondary transmitter of an underlay cognitive radio (CR) can be reduced by antenna selection. This paper analyzes different power adaptive transmit antenna selection (TAS) schemes for an underlay CR, which ensure that the instantaneous Interference caused by the secondary transmitter to the primary receiver is below a predetermined level. We consider the optimal continuous power adaptive TAS and present a low-complexity antenna and power level selection scheme, named sequential antenna and power level selection scheme (SAPS), for discrete power adaptation. Exact statistical characterizations of the signal-to-Interference plus noise ratio at the secondary receiver are derived for the considered schemes. Based on the newly derived statistics, we prove that the considered schemes achieve the highest diversity order equaling the number of antennas at the secondary transmitter. Further, we also derive a closed-form expression of the ergodic capacity for the underlay CR with SAPS scheme. Finally, we show that the proposed scheme outperforms existing schemes in terms of ergodic capacity.

  • receive antenna selection for underlay cognitive radio with instantaneous Interference Constraint
    IEEE Signal Processing Letters, 2015
    Co-Authors: Muhammad Hanif, Hongchuan Yang, Mohamedslim Alouini
    Abstract:

    Receive antenna selection is a low complexity scheme to reap diversity benefits. We analyze the performance of a receive antenna selection scheme in spectrum sharing systems where the antenna that results in highest signal-to-Interference plus noise ratio at the secondary receiver is selected to improve the performance of secondary transmission. Exact and asymptotic behaviours of the received SINR are derived for both general and Interference limited scenarios over general fading environment. These results are then applied to the outage and average bit error rate analysis when the secondary transmitter changes the transmit power in finite discrete levels to satisfy the instantaneous Interference Constraint at the primary receiver.

  • ergodic capacity of cognitive radio under imperfect channel state information
    IEEE Transactions on Vehicular Technology, 2012
    Co-Authors: Zouheir Rezki, Mohamedslim Alouini
    Abstract:

    A spectrum-sharing communication system where the secondary user is aware of the instantaneous channel-state information (CSI) of the secondary link but knows only the statistics and an estimated version of the secondary transmitter-primary receiver link is investigated. The optimum power profile and the ergodic capacity of the secondary link are derived for general fading channels [with a continuous probability density function (pdf)] under the average and peak transmit power Constraints and with respect to the following two different Interference Constraints: 1) an Interference outage Constraint and 2) a signal-to-Interference outage Constraint. When applied to Rayleigh fading channels, our results show, for example, that the Interference Constraint is harmful at the high-power regime, because the capacity does not increase with the power, whereas at the low-power regime, it has a marginal impact and no-Interference performance, which corresponds to the ergodic capacity under average or peak transmit power Constraint in the absence of the primary user, may be achieved.

  • ergodic capacity of cognitive radio under imperfect channel state information
    arXiv: Information Theory, 2012
    Co-Authors: Zouheir Rezk, Mohamedslim Alouini
    Abstract:

    A spectrum-sharing communication system where the secondary user is aware of the instantaneous channel state information (CSI) of the secondary link, but knows only the statistics and an estimated version of the secondary transmitter-primary receiver (ST-PR) link, is investigated. The optimum power profile and the ergodic capacity of the secondary link are derived for general fading channels (with continuous probability density function) under average and peak transmit-power Constraints and with respect to two different Interference Constraints: an Interference outage Constraint and a signal-to-Interference outage Constraint. When applied to Rayleigh fading channels, our results show, for instance, that the Interference Constraint is harmful at high-power regime in the sense that the capacity does not increase with the power, whereas at low-power regime, it has a marginal impact and no-Interference performance corresponding to the ergodic capacity under average or peak transmit power Constraint in absence of the primary user, may be achieved.

Daesik Hong - One of the best experts on this subject based on the ideXlab platform.

  • power allocation and outage probability analysis for secondary users in cognitive full duplex relay systems
    International Workshop on Signal Processing Advances in Wireless Communications, 2012
    Co-Authors: Hyungjong Kim, Hano Wang, Sungmook Lim, Daesik Hong
    Abstract:

    This paper investigates the use of full duplex relaying (FDR) in cognitive radio systems. Cognitive FDR systems offer the advantage not only of increasing spectral efficiency by spectrum sharing but also of extending the coverage through the use of relays. Concurrent transmissions at the source and relay in FDR systems can overcome a loss of resource efficiency in a way that conventional half duplex relay (HDR) systems cannot. However, in cognitive FDR systems, the primary user experiences Interference from the secondary source and relay simultaneously due to the full duplexing. Satisfying the Interference Constraint by simply reducing transmission power results in performance degradation for the secondary user. What is therefore needed is a way to optimize the transmission powers at the secondary source and relay. Therefore, we propose an optimal power allocation scheme based on minimizing the outage probability in cognitive FDR systems. We then analyze the outage probability of the secondary user in the noise-limited and Interference-limited environments. Simulation results show that the proposed schemes achieve performance improvement in terms of outage probability.

  • Optimal channel allocation for sensing-based cognitive radio systems in multichannel multiuser environment
    Proceedings of the 11th International Conference on Telecommunications, 2011
    Co-Authors: Gosan Noh, Hano Wang, Daesik Hong
    Abstract:

    This paper deals with the problem of allocating the multiple primary channels to the multiple secondary users in a sensing-based cognitive radio system. Traffic pattern deviation and SNR variation of the primary channels to each secondary user are exploited for the channel allocation. The sum-throughput of the secondary users is maximized by properly allocating the primary channels to the secondary users in a way of one-to-one mapping. The channel allocation can be realized via the sum-throughput maximization with Interference Constraint to the primary users. Numerical results show the throughput enhancement of the proposed channel allocation over the conventional one.

  • Outage Probability of Cognitive Relay Networks with Interference Constraints
    IEEE Transactions on Wireless Communications, 2011
    Co-Authors: Jemin Lee, Hano Wang, Jeffrey G. Andrews, Daesik Hong
    Abstract:

    This paper evaluates the outage probability of cognitive relay networks with cooperation between secondary users based on the underlay approach, while adhering to the Interference Constraint on the primary user, i.e., the limited amount of Interference which the primary user can tolerate. A relay selection criterion, suitable for cognitive relay networks, is provided, and using it, we derive the outage probability. It is shown that the outage probability of cognitive relay networks is higher than that of conventional relay networks due to the Interference Constraint, and we quantify the increase. In addition, the outage probability is affected by the distance ratio of the Interference link (between the secondary transmitter and the primary receiver) to the relaying link (between the secondary transmitter and the secondary receiver). We also prove that cognitive relay networks achieve the same full selection diversity order as conventional relay networks, and that the decrease in outage probability achieved by increasing the selection diversity (the number of relays) is not less than that in conventional relay networks.

Jae Hong Lee - One of the best experts on this subject based on the ideXlab platform.

  • outage probability for cooperative noma systems with imperfect sic in cognitive radio networks
    IEEE Communications Letters, 2019
    Co-Authors: Jae Hong Lee
    Abstract:

    In this letter, a cooperative non-orthogonal multiple access system with imperfect successive Interference cancellation is investigated in an underlay cognitive radio network. Considering that the channel coefficients between the primary source and the secondary receiving nodes follow Rayleigh distribution, we derive an exact closed form of the exact outage probability for each secondary destination. Also, asymptotic expressions for the outage probability are derived: 1) when the Interference Constraint goes to infinity and 2) when the transmit powers at the secondary source and relay go to infinity. The simulation results verify our analytical results.

  • outage probability of underlay cognitive radio networks with swipt enabled relay
    Vehicular Technology Conference, 2015
    Co-Authors: Jae Hong Lee
    Abstract:

    In this paper, we investigate an underlay relay-assisted cognitive radio network where a secondary relay harvests energy from a secondary source's signal. Outage probability of the secondary network is derived in closed form under a harvested energy Constraint at the relay and an Interference Constraint at the primary user. Also, optimal energy harvesting duration is obtained. Analytical results are verified by computer simulation.

Adrish Banerjee - One of the best experts on this subject based on the ideXlab platform.

  • optimal harvest or transmit strategy for energy harvesting underlay cognitive radio network
    International Conference on Signal Processing, 2018
    Co-Authors: Kalpant Pathak, Adrish Banerjee
    Abstract:

    An underlay cognitive radio network with energy harvesting is considered which operates in slotted fashion. The primary user (PU) transmits with a constant power in each slot, while the secondary user (SU) either harvests energy from primary's transmission or transmits its data. We propose an optimal offline harvest-or-transmit strategy where in each slot, SU takes a decision whether to harvest energy or transmit its data limiting Interference at the primary receiver. We aim to maximize the achievable rate of SU under energy causality and Interference Constraints. The optimization problem is formulated as a mixed integer non-linear program and the optimal harvest-or-transmit policy is obtained using generalized Benders decomposition algorithm. Through simulations, we analyze the effects of various system parameters and Interference Constraint at the primary receiver on the optimal policy.

  • maximizing sum outage capacity of ofdm based cognitive radio under primary user queue stability Constraint
    Wireless Communications and Networking Conference, 2014
    Co-Authors: Kedar Kulkarni, Adrish Banerjee
    Abstract:

    We consider a cognitive radio system in which primary user stores packets in a queue for transmission. For proper functioning of primary system, the cognitive user must ensure that primary queue remains stable. We show that such a queue stability Constraint can be converted to an equivalent Interference Constraint on cognitive user's transmission. Under this Constraint, we propose a power allocation technique to maximize sum of individual outage capacities achieved on each sub-channel of an OFDM based cognitive user. We present simulation results depicting effect of channel gains of direct links and Interference links on primary user's stable throughput and cognitive user's sum-outage capacity. The results show that proposed method performs better than only interweave mode of transmission used in literature.

  • power allocation for ofdm based cognitive radio systems under average Interference Constraint
    National Conference on Communications, 2013
    Co-Authors: Kedar Kulkarni, Adrish Banerjee
    Abstract:

    Power loading algorithms discussed in literature assume a static spectrum scenario where number of primary users remains constant in transmission period of cognitive user. In practice, new primary users can arrive or active primary users can depart at any time. In this paper we propose a new centralized power allocation technique taking into consideration arrival and departure of primary users that maximizes total capacity of cognitive user while honoring an average Interference Constraint. We also present numerical results to show that for known arrival and departure probabilities, the proposed method provides better primary protection than other static scenario based methods.

Gan Zheng - One of the best experts on this subject based on the ideXlab platform.

  • outage performance of cognitive hybrid satellite terrestrial networks with Interference Constraint
    IEEE Transactions on Vehicular Technology, 2016
    Co-Authors: Min Lin, Weiping Zhu, Yongming Huang, Gan Zheng
    Abstract:

    This paper investigates the performance of a cognitive hybrid satellite–terrestrial network, where the primary satellite communication network and the secondary terrestrial mobile network coexist, provided that the Interference temperature Constraint is satisfied. By using the Meijer-G functions, the exact closed-form expression of the outage probability (OP) for the secondary network is first derived. Then, the asymptotic result in a high-signal-to-noise-ratio (SNR) regime is presented to reveal the diversity order and coding gain of the considered system. Finally, computer simulations are carried out to confirm the theoretical results and reveal that a more loose Interference Constraint or heavier shadowing severity of a satellite Interference link leads to a reduced OP, whereas stronger satellite Interference power poses a detrimental effect on the outage performance.