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22
Cooperative Multi-hop Relaying via Network Formation Games in Cognitive Radio Networks
"... Abstract—The cooperation between the primary and the sec-ondary users has attracted a lot of attention in cognitive radio networks. However, most existing research mainly focuses on the single-hop relay selection for a primary transmitter-receiver pair, which might not be able to fully explore the b ..."
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Abstract—The cooperation between the primary and the sec-ondary users has attracted a lot of attention in cognitive radio networks. However, most existing research mainly focuses on the single-hop relay selection for a primary transmitter-receiver pair, which might not be able to fully explore the benefit brought by cooperative transmissions. In this paper, we study the problem of multi-hop relay selection by applying the network formation game. In order to mitigate interference and reduce delay, we propose a cooperation framework FTCO by considering the spectrum sharing in both the time and the frequency domain. Then we formulate the multi-hop relay selection problem as a network formation game, in which the multi-hop relay path is computed via performing the primary player’s strategies in the form of link operations. We also devise a distributed dynamic algorithm PRADA to obtain a global-path stable network. Finally, we conduct extensive numerical experiments and our results indicate that cooperative multi-hop relaying can significantly benefit both the primary and the secondary network, and that the network graph resulted from our PRADA algorithm can achieve the global-path stability. Index Terms—Cognitive radio networks; cooperative multi-hop relaying; network formation game; global-path stable network. I.
of Optimal Scheduling for Multi-Radio Multi-Channel Multi-Hop Cognitive Cellular Networks
"... Abstract—Due to the emerging various data services, current cellular networks have been experiencing a surge of data traffic and are already overloaded; thus, they are not able to meet the ever exploding traffic demand. In this study, we first introduce a multi-radio multi-channel multi-hop cognitiv ..."
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Abstract—Due to the emerging various data services, current cellular networks have been experiencing a surge of data traffic and are already overloaded; thus, they are not able to meet the ever exploding traffic demand. In this study, we first introduce a multi-radio multi-channel multi-hop cognitive cellular network (M3C2N) architecture to enhance network throughput. Under the proposed architecture, we then investigate the minimum length scheduling problem by exploring joint frequency allocation, link scheduling, and routing. In particular, we first formulate a maximal independent set based joint scheduling and routing optimization problem called original optimization problem (OOP). It is a mixed integer non-linear programming (MINLP) and generally NP-hard problem. Then, employing a column generation based approach, we develop an!-bounded approximation algorithm which can obtain an!-bounded approximate result of OOP. Noticeably, in fact we do not need to find the maximal independent sets in the proposed algorithm, which are usually assumed to be given in previous works although finding all of them is NP-complete. We also revisit the minimum length scheduling problem by considering uncertain channel availability. Simulation results show that we can efficiently find the!-bounded approximate results and the optimal result as well, i.e., when! 0 % in the algorithm. Index Terms—Cognitive cellular networks, multi-radio multi-channel multi-hop, cross-layer optimization, minimum length scheduling Ç 1
SUM: Spectrum Utilization Maximization in Energy-Constrained Cooperative Cognitive Radio Networks
"... Abstract—Cooperative cognitive radio networks (CCRNs) en-able secondary users (SUs) to access primary resource by cooperation with active primary users (PUs). For the cooperation-generated resource, existing schemes in CCRNs allocate the re-source only to the relay SUs. However, this may lead to ine ..."
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Abstract—Cooperative cognitive radio networks (CCRNs) en-able secondary users (SUs) to access primary resource by cooperation with active primary users (PUs). For the cooperation-generated resource, existing schemes in CCRNs allocate the re-source only to the relay SUs. However, this may lead to inefficient spectrum utilization, when the relay SUs have poor channel condition or little traffic load for their own secondary trans-missions. In this paper, considering user diversity in secondary networks, we focus on network-level throughput optimization for secondary networks, by allowing all SUs to optimally share the cooperation-generated period. Besides, considering the energy constraint on SUs, we formulate the resource allocation problem from long-term perspective, to reflect the time-varying change of user diversity in channel condition, traffic load and energy amount. We present an online SUM scheme to solve the long-term optimization problem. Although a mixed-integer and non-convex problem is involved in the SUM scheme, we transform the problem into multiple convex subproblems, and then optimally solve it with low computational complexity. Extensive simulations show that the proposed SUM scheme significantly outperforms the existing schemes. Index Terms—cognitive radio, cooperative communication, resource allocation, energy consumption. I.
Dynamic Spectrum Access and Power Allocation for Cooperative Cognitive Radio Networks
"... Abstract—In the existing cooperative cognitive radio, primary users are generally assumed to be more than capable of supporting their target throughput, thereby the rate enhancement or the co-operation from secondary users actually has less attraction to pri-mary users. Instead, they might be more i ..."
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Abstract—In the existing cooperative cognitive radio, primary users are generally assumed to be more than capable of supporting their target throughput, thereby the rate enhancement or the co-operation from secondary users actually has less attraction to pri-mary users. Instead, they might be more interested in the benefits in other format. This paper presents a new cooperative cognitive radio framework, where primary users are willing to cooperatively relay data for secondary users with their under-utilized resource to earn the revenue. An auction model with multiple auctioneers, multiple bidders and hybrid divisible/indivisible commodities is proposed to solve channel bands and cooperative transmit power competitions among secondary users. For maximizing the utility, secondary users can select receiving primary user’s assistance (i.e., work in cooperative transmission mode) and purchase both spec-trum and power from the primary user, or select direct transmis-sion mode and just buy spectrum from the primary user. Then, the convergence of the proposed auction scheme to a Walrasian equi-librium is mathematically proved. Finally, the performance of the proposed scheme is verified by the simulation results. Index Terms—Auction, cooperative cognitive radio, dynamic spectrum access, power allocation, Walrasian equilibrium. I.
Radio Resource Allocation for OFDM-Based Dynamic Spectrum Sharing: Duality Gap and Time Averaging
, 2014
"... Abstract—This paper considers radio resource allocation (RRA) in the downlink of an orthogonal frequency division multiple access (OFDM)-based spectrum-sharing network. The objective of RRA is to maximize the average achievable throughput subject to the primary service interference threshold and the ..."
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Abstract—This paper considers radio resource allocation (RRA) in the downlink of an orthogonal frequency division multiple access (OFDM)-based spectrum-sharing network. The objective of RRA is to maximize the average achievable throughput subject to the primary service interference threshold and the secondary service transmit power constraint. RRA is usually implemented based on a time window T over which system parameters are averaged and checked against resource constraints. We use short-term (T = 1 time slot) and long-term (T 1 slots) averaging as approximations to instantaneous and average constraints, re-spectively. RRA is also investigated for this system with long-term interference threshold and short-term interference threshold con-straints. RRA optimization is a nonconvex optimization problem in which the duality principle is adopted to obtain approximate solutions. The duality gap indicates the degree of approximation
1Implementation of Distributed Time Exchange Based Cooperative Forwarding
"... Abstract—In this paper, we design and implement time ex-change (TE) based cooperative forwarding where nodes use transmission time slots as incentives for relaying. We focus on distributed joint time slot exchange and relay selection in the sum goodput maximization of the overall network. We formula ..."
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Abstract—In this paper, we design and implement time ex-change (TE) based cooperative forwarding where nodes use transmission time slots as incentives for relaying. We focus on distributed joint time slot exchange and relay selection in the sum goodput maximization of the overall network. We formulate the design objective as a mixed integer nonlinear programming (MINLP) problem and provide a polynomial time distributed solution of the MINLP. We implement the designed algorithm in the software defined radio enabled USRP nodes of the ORBIT indoor wireless testbed. The ORBIT grid is used as a global control plane for exchange of control information between the USRP nodes. Experimental results suggest that TE can significantly increase the sum goodput of the network. We also demonstrate the performance of a goodput optimization algorithm that is proportionally fair.
Spectrum sharing in multi-channel cooperative cognitive radio networks: a coalitional game approach
"... Abstract In this paper, we study a coalitional game approach to resource allocation in a multi-channel coop-erative cognitive radio network with multiple primary users (PUs) and secondary users (SUs). We propose to form the grand coalition by grouping all PUs and SUs in a set, where each PU can leas ..."
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Abstract In this paper, we study a coalitional game approach to resource allocation in a multi-channel coop-erative cognitive radio network with multiple primary users (PUs) and secondary users (SUs). We propose to form the grand coalition by grouping all PUs and SUs in a set, where each PU can lease its spectrum to all SUs in a time-division manner while the SUs in return assist PUs ’ data trans-mission as relays. We use the solution concept of the core to analyze the stability of the grand coalition, and the solution concept of the Shapley value to fairly divide the payoffs among the users. Due to the convexity of the proposed game, the Shapley value is shown to be in the core. We derive the optimal strategy for the SU, i.e., transmitting its own data or serving as a relay, that maxi-mizes the sum rate of all PUs and SUs. The payoff allo-cations according to the core and the Shapley value are illustrated by an example, which demonstrates the benefits of forming the grand coalition as compared with non-coalition and other coalition schemes.
1Power Optimal Non-contiguous Spectrum Access
"... Wireless transmission using non-contiguous chunks of spectrum is becoming increasingly im-portant due to a variety of scenarios such as: secondary users avoiding incumbent users in TV white space; anticipated spectrum sharing between commercial and military systems; and spectrum sharing among uncoor ..."
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Wireless transmission using non-contiguous chunks of spectrum is becoming increasingly im-portant due to a variety of scenarios such as: secondary users avoiding incumbent users in TV white space; anticipated spectrum sharing between commercial and military systems; and spectrum sharing among uncoordinated interferers in unlicensed bands. Multi-Channel Multi-Radio (MC-MR) platforms and Non-Contiguous Orthogonal Frequency Division Multiple Access (NC-OFDMA) technology are the two commercially viable transmission choices to access these non-contiguous spectrum chunks. Fixed MC-MR’s do not scale with increasing number of non-contiguous spectrum chunks due to their fixed set of supporting radio front ends. NC-OFDMA allows nodes to access these non-contiguous spectrum chunks and put null sub-carriers in the remaining chunks. However, nulling sub-carriers increases the sampling rate (spectrum span) which, in turn, increases the power consumption of radio front ends. Our work characterizes this trade-off from a cross-layer perspective, specifically by showing how the slope of ADC/DAC’s power consumption versus sampling rate curve influences scheduling decisions in a multi-hop network. Specifically, we provide a branch and bound algorithm based mixed integer linear programming solution that performs joint power control, spectrum span selection, scheduling and routing in order to minimize the system power of multi-hop NC-OFDMA networks. We also provide a low complexity (O(E2M2)) greedy algorithm where M and E denote the number of channels and links respectively. Numerical simulations suggest that our approach reduces system power by 30 % over classical transmit power minimization based cross-layer algorithms. ar X iv
Article A Subcarrier-Pair Based Resource Allocation Scheme Using Proportional Fairness for Cooperative OFDM-Based Cognitive Radio Networks
, 2013
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1Technical Report: Investigation of Multiple Antennas for Cooperative Cognitive Radio Networks.
"... Recently, a new paradigm for cognitive radio networks has been advocated, where primary users (PUs) recruit the secondary users (SUs) to cooperatively relay the primary traffic, and in return grant the SUs the right to access the channel. However, all existing work on such cooperative cognitive radi ..."
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Recently, a new paradigm for cognitive radio networks has been advocated, where primary users (PUs) recruit the secondary users (SUs) to cooperatively relay the primary traffic, and in return grant the SUs the right to access the channel. However, all existing work on such cooperative cognitive radio networks (CCRNs) operate in the temporal domain only, which limits the performance of both PUs and SUs. On the other hand, Multiple-Input Multiple-Output (MIMO) enables transmission of multiple independent data streams in the spatial domain to improve capacity. Taking advantage of the MIMO technique in CCRNs is an unexplored area that we investigate in this paper. We propose a novel MIMO-CCRN framework, which enables the SUs to utilize MIMO techniques to cooperatively relay the traffic for the PUs, while concurrently accessing the same channel to transmit their own traffic. Specifically, we consider two typical network scenarios. For the case of a general PU link and multiple SUs, we provide theoretical analysis for the link rates and then formulate an optimization model based on a Stackelberg game to maximize the utilities of PUs and SUs. In addition, we extend our analysis to a practical cellular network with multiple MIMO-empowered femtocells, and provide an algorithm to find a stable matching of the PUs and SUs. Evaluation results show that high utility gains are achieved by both PUs and SUs by leveraging MIMO spatial cooperation in our proposed framework.
