• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.215-220
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• 2012

Recently, one of the research topics is wireless Ad-Hoc network minimizing power consumption because of limited power. We propose optimal power allocation scheme of each transmit node and derive performance analysis of system that recently designed Double opportunistic relay system which fixed branch receiver to use more than efficient power consumption. Optimal power location scheme is shown that outage probability has always better performance than equal power allocation. Furthermore, we are known that outage probability is minimized by increasing average transmit relays to obtain the diversity gain when average channel power gain is less.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.337-344
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• 2011

In this paper, a multiple-input and multiple-output (MIMO) spatial multiplexing (SM) relay system is studied in a bit error rate (BER) sense, where every node is deployed with multiple antennas. In order to efficiently use the limited power resource, it is essential to optimally allocate the power to nodes and antennas. In this context, the power allocation (PA) algorithm based on minimum BER (MBER) for a MIMO SM relay system is proposed, which is derived by direct minimization of the average BER, and divided into inter-node and inter-antenna PA algorithm. The proposed scheme outperforms the conventional equal power allocation (EPA) algorithm without extra power consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1241-1244
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• 2020

In this paper, we consider a downlink non-orthogonal multiple access system with a base station and N mobile stations, where we assume that instantaneous channel state information (CSI) is available at the base station. A power allocation scheme is proposed to achieve perfect fairness, which means equal data rates for all mobile stations. However, the power allocation scheme using full CSI requires high complexity. Hence, a simple power allocation scheme with low complexity is proposed by using high signal-to-noise power ratio (SNR) approximation. The simple power allocation scheme can achieve perfect fairness only for high SNR. However, it needs only the best CSI and the simple procedure to obtain power allocation coefficients. From simulation results, we show that the simple power allocation scheme provides remarkable fairness performance at high SNR.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.795-798
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• 2007

In this paper, we proposed a simple power allocation scheme to maximize network lifetime. To maximize network lifetime, it is important to allocate power fairly among nodes in a network as well as to minimize total transmitted power. In the proposed scheme, the allocated power is proportional to the residual power and also satisfies the required SNR at destination node. In this paper, we calculate power allocation in "amplify and forward" (AF) model. We evaluated the proposed power allocation scheme using extensive simulation and simulation results show that proposed power allocation obtains much longer network lifetime than the equal power allocation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.25-33
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• 2008

In this paper, the transmit power minimization for Poisson distributed wireless ad-hoc relay networks in Rayleigh fading channels is considered. We investigate two power allocation methods one is a minimum power allocation (MPA) strategy and the other is an equal outage power allocation (EOPA) strategy. We analyze the total transmit power of two allocation methods under the given end-to-end outage probability constraint. Our results show that the MPA achieves more power saving than EOPA, and the power saving is more significant as the number of relay nodes increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.9
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• pp.750-758
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• 2013

In this paper, we introduce the low-density parity-check (LDPC) coded orthogonal frequency division multiplexing (OFDM) subframe reordering scheme for achieving equal combined power allocation in type I hybrid automatic repeat request (H-ARQ) systems and analyze the performance improvement by using the channel capacity. Also, it is confirmed that the layered decoding for subframe reordering scheme in H-ARQ systems gives faster convergence speed. It is verified from numerical analysis that a subframe reordering pattern having larger channel capacity shows better bit error rate (BER) performance. Therefore the subframe reordering pattern achieving equal combined power allocation for each subframe maximizes the channel capacity and outperforms other subframe reordering patterns. Also, it is shown that the subframe reordering scheme for achieving equal combined power allocation gives better performance than the conventional Chase combining scheme without increasing the decoding complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1138-1146
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• 2008

This paper considers 2-hop wireless cooperative communications networks with fixed decode-and-forward relays. Specifically, we first derive the closed-form BER expression for theoretically evaluating the end-to-end performance of these networks. Then, based on this expression and long-tenn fading statistics, we propose a power allocation method for source and relay. Such a method brings about multiple advantages in tenn of spectral efficiency and implementation complexity over other power allocation methods based on instantaneous fading statistics. A variety of numerical results reveal that the cooperative communications scheme with the proposed power allocation significantly outperforms that with the equal power allocation and the direct transmission scheme for any position of the relay subject to the same total transmit power constraint.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.336-342
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• 2008

We proposed a simple power allocation scheme to maximize network lifetime for "amplify and forward(AF)" and "decode and forward(DF)". To maximize network lifetime, it is important to allocate power fairly among nodes in a network as well as to minimize total transmitted power. In the proposed scheme, the allocated power is proportional to the residual power and also satisfies the required SNR at destination node. In this paper, we calculate power allocation in model of AF and DF. We evaluated the proposed power allocation scheme using extensive simulation and simulation results show that proposed power allocation obtains much longer network lifetime than the equal power allocation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.1-8
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• 2009

Though the wireless ad-hoc network which is recently highly focused is power limited network, one of the main research topic is power saving. We propose a optimal power allocation strategy and derive the optimal power of the opportunistic transmission relays for minimum outage probability of the power limited network. It is shown that the proposed optimal power allocation has always better performance than that of the equal power allocation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3887-3907
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• 2015

This paper introduces a full duplex single secondary user multiple-input multiple-output (FD-SSU-MIMO) cognitive radio network, where secondary user (SU) opportunistically accesses the authorized spectrum unoccupied by primary user (PU) and transmits data based on FD-MIMO mode. Then we study the network achievable average sum-rate maximization problem under sum transmit power budget constraint at SU communication nodes. In order to solve the trade-off problem between SU's sensing time and data transmission time based on opportunistic spectrum access (OSA) and the power allocation problem based on FD-MIMO transmit mode, we propose a simple trisection algorithm to obtain the optimal sensing time and apply an alternating optimization (AO) algorithm to tackle the FD-MIMO based network achievable sum-rate maximization problem. Simulation results show that our proposed sensing time optimization and AO-based optimal power allocation strategies obtain a higher achievable average sum-rate than sequential convex approximations for matrix-variable programming (SCAMP)-based power allocation for the FD transmission mode, as well as equal power allocation for the half duplex (HD) transmission mode.