G.A.S. Sidhu

Jacobs University, Bremen, Bremen, Germany

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Publications (10)3.81 Total impact

  • G.A.S. Sidhu, Feifei Gao, Wei Wang, Wen Chen
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    ABSTRACT: In this paper, we investigate the resource allocation problem in a single-user relay-aided cognitive radio (CR) underlay network. Both the CR network and the primary network operate under the orthogonal frequency-division multiplexing (OFDM) scheme. Different from the conventional resource allocation problem, the relay node here is capable of performing subcarrier permutation over two hops such that the signal received over a particular subcarrier is forwarded via a different subcarrier. The objective is to maximize the throughput of the CR network subject to a limited power budget at the secondary source and the relay node and to interference constraints at the primary receiver. Optimization is performed under a unified framework where power allocation at the source node, power allocation at the relay node, and subcarrier pairing at the two hops are jointly optimized. The joint resource-allocation scheme yields an asymptotically optimal solution. We further design a suboptimal algorithm that sacrifices little on performance but could significantly reduce computational complexity. Finally, numerical examples are provided to corroborate the proposed studies.
    IEEE Transactions on Vehicular Technology 01/2013; 62(8):3700-3710. · 2.06 Impact Factor
  • Guftaar Ahmad Sardar Sidhu, Feifei Gao, Wen Chen, Wei Wang
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    ABSTRACT: This paper investigates the resource allocation problem in a relay-aided cognitive radio (CR) system under the orthogonal frequency division multiplexing (OFDM) transmission. Different from the conventional CR resource allocation problem, the relay node here is capable of performing subcarrier permutation over two hops such that the signal received over a particular subcarrier is forwarded on a different subcarrier. The objective is to maximize the throughput of the CR network subject to a limited power budget at the secondary source and relay node, as well as the interference constraints at the primary receiver. The optimization is performed under a unified framework where the power allocation at the source node, power allocation at the relay node, and subcarrier pairing at the two hops are optimized jointly. Finally, numerical examples are provided to corroborate the proposed studies.
    01/2012;
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    ABSTRACT: In this paper, we study the joint resource allocation problem in multi-carrier multi-relay aided dual hop single-user communication. We adopt orthogonal frequency division multiplexing (OFDM) as the transmission modulation and consider amplify-and-forward (AF) relaying scheme. The optimization is performed over power allocation at source node, beamforming at relay nodes and subcarrier pairing at two hops, such that the overall system throughput is maximized under limited power budget at the source and relay nodes. The optimization is a mixed integer programming problem which is solved through dual decomposition approach. To further reduce the complexity, we propose a suboptimal algorithm which sacrifices very little on the performance. Finally, simulation results are provided to corroborate the proposed studies.
    Communications (ICC), 2012 IEEE International Conference on; 01/2012
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    ABSTRACT: In this paper, we explore resource optimization problem in dual hop multi-carrier amplify and forward (AF) based relay networks. First, we consider an orthogonal transmission where the source and relay stations transmit information in different time slots. We investigate the joint optimization of subcarrier matching over two hops and the power allocation over different subcarriers at the source and the relay nodes. Although the joint optimization problem under power and subcarrier constraints is a mixed integer programming problem, we propose an efficient solution based on the dual decomposition approach. Then, we present a selection scheme where a single best relay is selected for the dual hop communication. Finally, simulation results are provided to corroborate the proposed studies.
    Communications in China Workshops (ICCC), 2012 1st IEEE International Conference on; 01/2012
  • Source
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    ABSTRACT: In this letter, we study the problem of resource allocation in amplify-and-forward (AF) based multiuser two-way relay network that is operated under orthogonal frequency division multiple access (OFDMA) modulation. We formulate an end-to-end throughput maximization problem subject to limited power constraint at individual user and relay. The optimization targets to find the best sub-carrier allocation to each user, sub-carrier pairing at the relay, as well as the power allocation at all nodes, which turns out to be a mixed integer programming problem. We then derive an asymptotically optimal solution through Lagrange dual decomposition approach and further design a suboptimal algorithm to trade the performance for computational complexity. Finally, simulation results are provided to demonstrate the performance gain of the proposed algorithms.
    IEEE Transactions on Communications 12/2011; · 1.75 Impact Factor
  • Guftaar Ahmad Sardar Sidhu, Feifei Gao, Lisheng Fan, Arumugam Nallanathan
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    ABSTRACT: In this paper, we study the problem of resource allocation in orthogonal frequency division multiple access (OFDMA) based multi-user dual-hop uplink transmission where a single relay station is deployed between the mobile users and the base station which operates under amplify-and-forward (AF) relaying mode. The optimization targets to maximize the overall system throughput through joint optimization of sub-carrier allocation, sub-carrier pairing, and the power allocation, subject to individual power constraint at each node. The optimization results in mixed integer programming problem and a near optimal solution is obtained through dual decomposition approach. Further, we develop a suboptimal scheme to trade the performance for lower complexity. Finally, numerical examples are provided to demonstrate the performance gain of the proposed schemes.
    Proceedings of the Global Communications Conference, GLOBECOM 2011, 5-9 December 2011, Houston, Texas, USA; 01/2011
  • G.A. Sidhu, Feifei Gao
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    ABSTRACT: In this paper, we study the resource allocation problem in relay aided two-hop uplink multi-user transmission with a single relay node and a single destination node. The orthogonal frequency division multiple access (OFDMA) is adopted as the main transmission modulation. We investigate the problems of subcarrier allocation, subcarrier coupling, and power allocation. The optimization is formulated as maximizing the capacity under constraints of limited number of available subcarriers and a limited amount of power for each source node. A low complexity, suboptimal solution is presented to solve the problem. Simulation results are presented to evaluate the performance of the proposed algorithm.
    Wireless Communications and Networking Conference (WCNC), 2010 IEEE; 05/2010
  • Guftaar Ahmad Sidhu, Xuewen Liao, Feifei Gao
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    ABSTRACT: In this paper, we study the problem of the lifetime maximization in a new type of multi-hop relay network where the amplify-and-forward (AF) and the decode-and-forward (DF) relay nodes are alternatingly cascaded. In order to cope with the general frequency selective fading channel, the orthogonal frequency division multiplexing (OFDM) modulation is adopted over each hop. We formulate the optimization problem as maximizing the network lifetime subject to the constraint of minimum end-to-end rate requirement, while each relay node is constrained to its limited battery energy as well as the maximum power supply. Under certain assumptions, we transform the original problem into the standard convex optimization problem and solve it from the dual decomposition technique. Simulation results are provided to corroborate the proposed strategy.
    01/2010;
  • G.A.S. Sidhu, Feifei Gao, A. Nallanathan
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    ABSTRACT: In this paper, we consider the problem of resource allocation in relay aided uplink multi-user transmission with a single destination node. We adopt the amplify-and-forward (AF) relaying scheme and the orthogonal frequency division multiple access (OFDMA) as the main transmission modulation. The optimization is formulated as maximizing the end-to-end system throughput subject to limited number of sub-carriers and a limited amount of power for each individual user as well as the relay node. The optimization is a mixed integer programming problem over the sub-carrier allocation to each user, sub-carrier pairing at the relay, the power allocation of each user, and the power allocation at the relay. With the aid of dual decomposition, we find the near optimal solutions with acceptable complexity. To further reduce the complexity, we present a suboptimal algorithm which sacrifices very little on the performance. Finally, simulation results are provided to corroborate the proposed studies.
    Wireless Communications and Signal Processing (WCSP), 2010 International Conference on; 01/2010
  • Source
    K. Hassan, G. Sidhu, W. Henkel
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    ABSTRACT: In this paper, an orthogonal multiple access scheme is considered for different users with different quality of service (QoS) requirements. Therefore, the users are multiplexed using orthogonal frequency division multiple access (OFDMA) transmission. A multiple-input multiple-output (MIMO) antenna system is considered between the base-station (BS) and the existing mobile sets (MSs). In order to realize different QoS, the transmission bit-rates and powers are adapted to the various channel conditions with different margin separations. In here, we proposed two different subcarrier sorting schemes in order to exploit the multiuser diversity and to enhance the performance in case of channel uncertainties. Accordingly, our simulations examine the performance of the downlink (broadcast) channel adaptation for different channel conditions assuming a single cell scenario.
    Communications Workshops, 2009. ICC Workshops 2009. IEEE International Conference on; 07/2009