Article

# Difference Antenna Selection and Power Allocation for Wireless Cognitive Systems

(Impact Factor: 1.99). 10/2010; 59(12). DOI: 10.1109/TCOMM.2011.091911.100633
Source: arXiv

ABSTRACT

In this paper, we propose an antenna selection method in a wireless cognitive radio (CR) system, namely difference selection, whereby a single transmit antenna is selected at the secondary transmitter out of $M$ possible antennas such that the weighted difference between the channel gains of the data link and the interference link is maximized. We analyze mutual information and outage probability of the secondary transmission in a CR system with difference antenna selection, and propose a method of optimizing these performance metrics of the secondary data link subject to practical constraints on the peak secondary transmit power and the average interference power as seen by the primary receiver. The optimization is performed over two parameters: the peak secondary transmit power and the difference selection weight $\delta\in [0, 1]$. We show that, difference selection using the optimized parameters determined by the proposed method can be, in many cases of interest, superior to a so called ratio selection method disclosed in the literature, although ratio selection has been shown to be optimal, when impractically, the secondary transmission power constraint is not applied. We address the effects that the constraints have on mutual information and outage probability, and discuss the practical implications of the results. Comment: 29 pages, 9 figures, to be submitted to IEEE Transactions on Communications

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Available from: Justin Coon, Oct 04, 2015
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• "For MIMO systems, one drawback is that the multiple antennas should be associated with the multiple radio frequency (RF) chains, which are costly in terms of size, power, and hardware [5]–[7]. One feasible solution to overcome this drawback is the antenna selection (AS) scheme [8]–[11], which provides a good tradeoff between cost, complexity and performance. The key idea of AS scheme is to allocate the limited available RF chains to the transmit and receive antennas, between which the wireless links have the highest signal-to-noise ratio (SNR). "
##### Article: Antenna Selection for Simultaneous Wireless Information and Power Transfer in MIMO Systems
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ABSTRACT: For simultaneous wireless information and power transfer in multiple-input multiple-output broadcast systems, we propose to investigate the antenna selection (AS) design problem. The problem is formulated as joint AS and transmit covariance matrix design optimization problem which maximizes the achievable rate from the transmitter to the information-decoding receiver subject to the energy-harvesting constraint and the transmit power constraint. To solve the problem, we relax the binary constraints on the AS matrices and restrict the transmit covariance matrix to be diagonal. The AS matrices and the transmit covariance matrix are optimized iteratively by our proposed iterative AS algorithm. We also propose a low-complexity non-iterative norm-based algorithm which optimizes the AS matrices and the transmit covariance matrix sequentially. It is shown from simulation results that the achievable rates of proposed algorithms approach that of the AS scheme which is optimized by exhaustive search.
IEEE Communications Letters 03/2014; 18(5). DOI:10.1109/LCOMM.2014.031514.140136 · 1.27 Impact Factor
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• "It is obvious that we may need to determine the PDF and CDF expressions in order to derive performance analysis of the proposed CR system. Indeed, without such information, previous works failed to derive accurate closed form expressions for the performance metrics when using ratio selection at the secondary transmission in CR systems [13]. "
##### Article: Exact Performance Analysis of MIMO Cognitive Radio Systems Using Transmit Antenna Selection
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ABSTRACT: We consider in this paper, a spectrum sharing cognitive radio system with a ratio selection scheme; where one out of N independent-and-identically-distributed transmit antennas is selected such that the ratio of the secondary transmitter (ST) to the secondary receiver (SR) channel gain to the interference from the ST to the primary receiver (PR) channel gain is maximized. Although previous works considered perfect, outdated, or partial channel state information at the transmitter, we stress that using such assumptions may lead to a feedback overhead for updating the SR with the ST-PR interference channel estimation. Considering only statistical knowledge of the ST-PR channel gain, we investigate a ratio selection scheme using a mean value (MV)-based power allocation strategy referred to as MV-based scheme. We first provide the exact statistics in terms of probability density function and cumulative distribution function of the secondary channel gain as well as of the interference channel gain. Furthermore, we derive exact cumulative density function of the received signal-to-noise ratio at the SR where the ST uses a power allocation based on instantaneous perfect channel state information (CSI) referred to as CSI-based scheme. These statistics are then used to derive exact closed form expressions of the outage probability, symbol error rate, and ergodic capacity of the secondary system when the interference channel from the primary transmitter (PT) to the SR is ignored. Furthermore, an asymptotical analysis is also carried out for the MV-based scheme as well as for the CSI-based scheme to derive the generalized diversity gain for each. Subsequently, we address the performance analysis based on exact statistics of the combined signal-to-interference-plus-noise ratio at the SR of the more challenging case; when the PT-SR interference channel is considered. Numerical results in a Rayleigh fading environment manifest that the MV-based scheme outperforms the CSI-based s- heme provided that a low interference power constraint is deployed, implying that the MV-based scheme is more suitable for practical systems.
IEEE Journal on Selected Areas in Communications 03/2014; PP(99):1-14. DOI:10.1109/JSAC.2014.140305 · 3.45 Impact Factor
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• "Accordingly, the quality of service (QoS) of the SU may be under expectation. As an effort to overcome this problem, some works opted to create frequency diversity on both secondary and interference channels [10]–[13], and other works opted to create spatial diversity by equipping the secondary transmitter with several antennas [11], [14]–[16]. At the same time, cooperative diversity schemes have been very attractive for small-size and antenna-limited wireless devices, and cooperative diversity emerged as a powerful spatial diversity technology that can mitigate channel impairments and enhance the overall capacity [17]. "
##### Article: Outage Analysis for Underlay Cognitive Networks Using Incremental Regenerative Relaying
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ABSTRACT: Cooperative relay technology has recently been introduced into cognitive radio (CR) networks to enhance the network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service (QoS) of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. Analysis is conducted for two schemes, referred to as the channel-state information (CSI)-based and fault-tolerant schemes, respectively, where different amounts of CSI were considered. We first provide the exact cumulative distribution function (cdf) of the received signal-to-noise ratio (SNR) over each hop with colocated relays. Then, the cdf's are used to determine a very accurate closed-form expression for the outage probability for a transmission rate R. In a high-SNR region, a floor of the secondary outage probability occurs, and we derive its corresponding expression. We validate our analysis by showing that the simulation results coincide with our analytical results in Rayleigh fading channels.
IEEE Transactions on Vehicular Technology 02/2013; 62(2):721-734. DOI:10.1109/TVT.2012.2222947 · 1.98 Impact Factor