Difference Antenna Selection and Power Allocation for Wireless Cognitive Systems

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


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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    • "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). "
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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]. "
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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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    • "However, and following the same system model, Wang and Coon proposed a new transmit antenna selection, called as difference antenna selection, under peak and average interference power constraint [12]. They derived closed form expression for the secondary outage probability as function of the difference selection weight and the secondary transmit power. "
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    ABSTRACT: In this paper, we consider a spectrum sharing cognitive radio system with ratio selection using a mean value-based power allocation strategy. We first provide the exact statistics in terms of probability density function and cumulative density function of the secondary channel gain as well as of the interference channel gain. These statistics are then used to derive exact closed form expression of the secondary outage probability. Furthermore, asymptotical analysis is derived and generalized diversity gain is deduced. We validate our analysis with simulation results in a Rayleigh fading environment.
    Communications (ICC), 2013 IEEE International Conference on; 06/2013
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