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Riskaware cooperative spectrum access for multi-channel cognitive radio networks
- IEEE J. Sel. Areas Commun
"... Abstract—In this paper, risk-aware cooperative spectrum ac-cess schemes for cognitive radio networks (CRNs) with multiple channels are proposed, whereby multiple primary users (PUs) operating over different channels choose trustworthy secondary users (SUs) as relays to improve throughput, and in ret ..."
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Abstract—In this paper, risk-aware cooperative spectrum ac-cess schemes for cognitive radio networks (CRNs) with multiple channels are proposed, whereby multiple primary users (PUs) operating over different channels choose trustworthy secondary users (SUs) as relays to improve throughput, and in return SUs gain transmission opportunities. To study the multi-channel cooperative spectrum access, cooperation over single channel is investigated first, which involves a PU selecting the suitable SU and granting a period of access time to the selected SU as a reward, considering trustworthiness of SUs. The above procedure is modeled as a Stackelberg game, through which access time allocation and power allocation are obtained. Based on the above results, cooperation over multiple channels is studied from the perspectives of the primary network and secondary network, respectively. Two schemes are proposed accordingly: the primary network-centric matching (PCM) scheme and the secondary network-centric cluster-based (SCC) scheme. In PCM scheme, cooperating SU for each channel is determined to maximize the total utility of the primary network, which is formulated as a maximum weight matching problem. In SCC scheme, SUs first form a cluster to share the channel state information (CSI), and the best SUs are selected for cooperation with PUs over different channels to obtain the maximum aggregate access time for the secondary network. Then, SUs share the obtained resource using congestion game and quadrature signalling. Numerical results demonstrate that, with the proposed schemes, PUs can achieve higher throughput, while SUs can obtain longer average access time, compared with the random channel access approach. Index Terms—Cognitive radio, stackelberg game, congestion game, maximum weight matching. I.
Dynamic Cooperative Secondary Access in Hierarchical Spectrum Sharing Networks
"... Abstract-We consider a hierarchical spectrum sharing network consisting of a primary and a cognitive secondary transmitter-receiver pair, with non-backlogged traffic. The secondary transmitter may utilize cooperative transmission techniques to relay primary traffic while superimposing its own infor ..."
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Abstract-We consider a hierarchical spectrum sharing network consisting of a primary and a cognitive secondary transmitter-receiver pair, with non-backlogged traffic. The secondary transmitter may utilize cooperative transmission techniques to relay primary traffic while superimposing its own information, or transmit opportunistically when the primary user is idle. The secondary user meets a dilemma in this scenario. Choosing cooperation it can transmit a packet immediately even if the primary queue is not empty, but it has to bear the additional cost of relaying, since the primary performance needs to be guaranteed. To solve this dilemma we propose dynamic cooperative secondary access control that takes the state of the spectrum sharing network into account. We formulate the problem as a Markov Decision Process (MDP) and prove the existence of a stationary policy that is average cost optimal. Then we consider the scenario when the traffic and link statistics are not known at the secondary user, and propose to find the optimal transmission strategy using reinforcement learning. With extensive numerical evaluation, we demonstrate that dynamic cooperation with state aware sequential decision is very efficient in spectrum sharing systems with stochastic traffic, and show that dynamic cooperation is necessary for the secondary system to be able to adapt to changing load conditions or to changing available energy resource. Our results show, that learning based access control, with or without known primary buffer state, has close to optimal performance. Index Terms-Hierarchical spectrum sharing, cooperative transmission, queuing systems, Markov decision process, reinforcement learning.
DOI: 10.1109/ICASSP.2013.6638669 PERFORMANCE OF FADING MULTI-USER DIVERSITY FOR UNDERLAY COGNITIVE NETWORKS †
"... The effect of multi-user diversity in an underlay network with independent and identically distributed (i.i.d) Rayleigh fading was initially studied in [8]. It was shown in [8] that at sufficiently high transmit power, the selection of the user is more influenced by the interference link and the mul ..."
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The effect of multi-user diversity in an underlay network with independent and identically distributed (i.i.d) Rayleigh fading was initially studied in [8]. It was shown in [8] that at sufficiently high transmit power, the selection of the user is more influenced by the interference link and the multi-user diversity gain in terms of capacity scales similar to the scaling law of the non-spectrum sharing system. The ergodic capacity of the multi-user underlay system was derived for a more generic hyper-Nakagami-m fading channel in [9]. The outage capacity as well as the effective capacity for an opportunistic cognitive broadcast channel having i.i.d Rayleigh fading was analyzed in [10]. Multi-user interference diversity which takes into account the interference from the primary network was studied in [11]. In [12], a new hybrid scheduling scheme was proposed which selects SUs for transmission in two steps; 1) First a subset of SUs is selected that have the interference link in deep fade and 2) then the SUs with the best transmishal-00925984,
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.
UPS: A United Cooperative Paradigm for Primary and Secondary Networks
"... Abstract—The dominant spectrum sharing paradigm of today is the interweave paradigm. This paper advocates a new and alternative paradigm called United network of Primary and Secondary networks (UPS). UPS allows a complete cooperation between primary and secondary networks at the node level to relay ..."
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Abstract—The dominant spectrum sharing paradigm of today is the interweave paradigm. This paper advocates a new and alternative paradigm called United network of Primary and Secondary networks (UPS). UPS allows a complete cooperation between primary and secondary networks at the node level to relay each other’s traffic, in addition to existing dynamic spectrum access (DSA) in time, space, and frequency domains. Such cooperation allows the primary and secondary networks to access a much richer network resources from the combined network. As a case study, we consider a problem with the goal of supporting the rate requirement of the primary network traffic while maximizing the minimum throughput of the secondary sessions. For this problem, we develop an optimization model and formulate a combinatorial optimization problem. Although this problem is in the form of mixed integer linear program (MILP), we can use CPLEX to solve it efficiently. Simulation results show that the UPS paradigm offers much better throughput performance than the interweave DSA paradigm. I.
1Risk-aware Cooperative Spectrum Access for Multi-Channel Cognitive Radio Networks
"... Abstract—In this paper, risk-aware cooperative spectrum ac-cess schemes for cognitive radio networks (CRNs) with multiple channels are proposed, whereby multiple primary users (PUs) operating over different channels choose trustworthy secondary users (SUs) as relays to improve throughput, and in ret ..."
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Abstract—In this paper, risk-aware cooperative spectrum ac-cess schemes for cognitive radio networks (CRNs) with multiple channels are proposed, whereby multiple primary users (PUs) operating over different channels choose trustworthy secondary users (SUs) as relays to improve throughput, and in return SUs gain transmission opportunities. To study the multi-channel cooperative spectrum access, cooperation over single channel is investigated first, which involves a PU selecting the suitable SU and granting a period of access time to the selected SU as a reward, considering trustworthiness of SUs. The above procedure is modeled as a Stackelberg game, through which access time allocation and power allocation are obtained. Based on the above results, cooperation over multiple channels is studied from the perspectives of the primary network and secondary network, respectively. Two schemes are proposed accordingly: the primary network-centric matching (PCM) scheme and the secondary network-centric cluster-based (SCC) scheme. In PCM scheme, cooperating SU for each channel is determined to maximize the total utility of the primary network, which is formulated as a maximum weight matching problem. In SCC scheme, SUs first form a cluster to share the channel state information (CSI), and the best SUs are selected for cooperation with PUs over different channels to obtain the maximum aggregate access time for the secondary network. Then, SUs share the obtained resource using congestion game and quadrature signalling. Numerical results demonstrate that, with the proposed schemes, PUs can achieve higher throughput, while SUs can obtain longer average access time, compared with the random channel access approach. Index Terms – Cognitive radio, stackelberg game, congestion game, maximum weight matching. I.
PERFORMANCE OF FADING MULTI-USER DIVERSITY FOR UNDERLAY COGNITIVE NETWORKS†
"... Having multiple secondary users (SUs) can be exploited to achieve multiuser diversity and improve the throughput of the underlay secondary network. In the cognitive setting, sat-isfying the interference constraint is essential, and thus, a scheduling scheme is considered where some SUs are pre-selec ..."
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Having multiple secondary users (SUs) can be exploited to achieve multiuser diversity and improve the throughput of the underlay secondary network. In the cognitive setting, sat-isfying the interference constraint is essential, and thus, a scheduling scheme is considered where some SUs are pre-selected based on the low interference power. From this sub-set, the SU that yields the highest throughput is selected for transmission. This scheduling scheme helps to lower the in-terference power while giving good throughput. For an in-dependent but not identically distributed Nakagami-m fading channel, we obtain exact closed-form expressions of the ca-pacity of this scheduling scheme. Furthermore, the schedul-ing time of SUs is characterized and closed-form expressions for the mean time after which a SU is selected for transmis-sion are obtained. Numerical simulations are performed to corroborate the derived analytical results. Our results show that at low interference threshold, increasing transmit power of the SUs is not beneficial and results in reduced capacity. Furthermore, the channel idle time (i.e. time that no user is utilizing the channel) reduces with increasing the number of SUs.
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, 2010
"... HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte p ..."
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
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.
