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Socially optimal queuing control in cognitive radio networks subject to service interruptions: to queue or not to queue
- IEEE Transaction on Wireless Communications
, 2011
"... Abstract—The main challenge to cognitive radio is the emer-gence of primary users, which can be considered as the service interruptions in a queuing system. The service interruption can incur significant delays for secondary users ’ data packets which are considered as secondary customers. Therefore ..."
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Abstract—The main challenge to cognitive radio is the emer-gence of primary users, which can be considered as the service interruptions in a queuing system. The service interruption can incur significant delays for secondary users ’ data packets which are considered as secondary customers. Therefore, a secondary customer needs to decide whether to join the queue or leave for other means of transmission. It is shown that the individually optimal strategy for joining the queue is characterized by a threshold of queue length. When the current queue length is above this threshold, the secondary customer should leave; otherwise it should join the queue. The socially optimal threshold of queue length is also obtained and is numerically shown to be smaller than the individually optimal one, which implies that the individually optimal strategy does not yield the socially optimal one. To bridge the gap between the individually and socially optimal strategies, a pricing mechanism is proposed to toll the service of each secondary customer, thus equalizing the two optimal strategies. When the channel statistics are unknown, an online learning procedure, based on the Kiefer-Wolfowitz algorithm, is proposed. The proposed algorithms are then demonstrated using numerical simulations. Index Terms—Cognitive radio, queuing control, service inter-ruption. I.
Non-cooperative Spectrum Access – The Dedicated vs. Free Spectrum Choice
"... We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this decision is between immediate yet costly transmission and free but de ..."
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Cited by 12 (1 self)
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We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this decision is between immediate yet costly transmission and free but delayed transmission (a consequence of both the possible appearance of PUs and sharing the spectrum holes with multiple SUs). We first consider a system with a single PU band, in which the SU decisions are fixed. Employing queueing-theoretic methods, we obtain explicit expressions for the expected delays associated with using the PU band. Based on that, we then consider self-interested SUs and study the interaction between them as a noncooperative game. We prove the existence and uniqueness of a symmetric Nash equilibrium, and characterize the equilibrium behavior explicitly. Using our equilibrium results, we show how to maximize revenue from renting dedicated bands to SUs. Finally, we extend the scope to a scenario with multiple PUs, show that the band-pricing analysis can be applied to some special cases, and provide numerical examples.
Delay Performance of Threshold Policies for Dynamic Spectrum Access
"... Abstract—In this paper, we analyze the delay performance of a secondary user (SU) under dynamic spectrum access. We design simple time-threshold policies for the SU to minimize the average delay while satisfying the collision probability constraint of the primary user (PU). Such policies perform clo ..."
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Cited by 4 (0 self)
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Abstract—In this paper, we analyze the delay performance of a secondary user (SU) under dynamic spectrum access. We design simple time-threshold policies for the SU to minimize the average delay while satisfying the collision probability constraint of the primary user (PU). Such policies perform closely to an optimized policy found by a Markov Decision Process (MDP) formulation, while facilitating analytical analysis of the delay and collision probability. For general PU busy and idle period distributions, we analyze the performance of threshold policies through a onedimensional Markov chain, and develop analytical expressions to approximate the delay and collision probability. The accuracy of the Markov chain analysis and the analytical approximations is examined under various busy and idle distributions. We investigate the impact of busy and idle distributions on system performance. We find that while the idle distribution determines the time capacity of SU access, the busy distribution significantly affects the delay performance of the threshold policies. The effect of imperfect sensing is also studied. Index Terms—Cognitive radio, dynamic spectrum access, delay, collision probability, Markov Decision Process.
Adaptive spectrum opportunity access in cognitive radio networks
- Journal of Networks
, 2013
"... Abstract- This paper presents the Adaptive Spectrum Opportunity Access (ASOA) scheme. The proposed scheme greatly improves spectrum utilization and provides improved QoS for the secondary users. The secondary data delivery time is adapted in different spectrum opportunities through ASOA scheme based ..."
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Abstract- This paper presents the Adaptive Spectrum Opportunity Access (ASOA) scheme. The proposed scheme greatly improves spectrum utilization and provides improved QoS for the secondary users. The secondary data delivery time is adapted in different spectrum opportunities through ASOA scheme based on the estimated collision rates in a sophisticated way. The performance evaluations in terms of the channel utilization, channel collision, secondary data delivery and handoff rates are assessed and compared with the Maximum Idle Channel Remaining Lifetime (MICRL) schemes. The simulation results confirm the viability of the ASOA scheme in comparison with MICRL schemes.
Extended Delivery Time Analysis for Cognitive Packet Transmission with Application to Secondary Queuing Analysis
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Performance Analysis of Emerging Solutions to RF Spectrum Scarcity Problem in Wireless Communications
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Dynamic Spectrum Access Strategy for Multi-Channel Cognitive Radio Networks
"... In this paper, we present a dynamic spectrum access strategy to reduce the average overall system time of secondary users (SUs) in multi-channel cognitive radio networks. Before transmitting a packet, SU senses the spectrum environment. If there are free channels in the system, SU randomly selects o ..."
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In this paper, we present a dynamic spectrum access strategy to reduce the average overall system time of secondary users (SUs) in multi-channel cognitive radio networks. Before transmitting a packet, SU senses the spectrum environment. If there are free channels in the system, SU randomly selects one for transmitting. If all the channels are busy, we consider a probability-based spectrum selection scheme in which the access channel is chosen based on the predetermined probabilities for saving the sensing power and reducing the overall system time of SU. When the transmission of SU is preempted by the primary user (PU), SU will stay on the operating channel and retransmit the whole data after PU leaves the channel. SU may undergo multiple interruptions before finishing a successful transmission. The interruptions and retransmissions inevitably increase the overall system time of SU. We propose an analytical model by applying the preemptive repeat identical priority M/G/1 queueing theory. Based on the model, we obtain the overall system time expression of SU packets under different spectrum environment and find the optimal distribution vector for the probabilitybased spectrum access scheme to minimize the average overall system time for SU.
Research Article Analysis of the M/M/N/N Queue with Two Types of Arrival Process: Applications to Future Mobile Radio Systems
"... Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The queueing system considered is essentially a M/M/N/N queue where two types of users compete for the N resources. The users may have different ar ..."
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Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The queueing system considered is essentially a M/M/N/N queue where two types of users compete for the N resources. The users may have different arrival and service rates and are denoted as primary or secondary users. The primary users have priority access to the resources, and three levels of priority are considered: perfect priority, partial priority, and no priority. This system models the recently developed cognitive radio concept, a methodology that has been proposed for future mobile radio systems. In this context, the primary users have certain rights to use the resources, whereas the secondary users must make opportunistic use of the resources without impacting too much on the performance of the primary users. For all priority settings, the mean number of primary and secondary users is derived as are the blocking probabilities for both users. When no priority is given to the primary user, the system collapses to a truncated form of two independent M/M/ ∞ queues. The product form solution for this special case is known, and, here, these results are given in a novel, compact form. In the case of nonzero priority, the dropping probability for the secondary users is also derived. 1.
A FRAMEWORK FOR DATA TRAFFIC IN COGNITIVE RADIO NET- WORKS USING TRUSTED TOKEN ANALYZER SCHEME
"... A cognitive radio network is considered as a key technology for future wireless communications. The motivation behind cognitive ra-dio is the effective usage of limited spectrum. Cognitive radio networks are designed to opportunistically exploit the underutilized or unused spectrum bands. Cognitive ..."
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A cognitive radio network is considered as a key technology for future wireless communications. The motivation behind cognitive ra-dio is the effective usage of limited spectrum. Cognitive radio networks are designed to opportunistically exploit the underutilized or unused spectrum bands. Cognitive radio combines sensing, learning, and optimization algorithms to manage and adapt the radio sys-tem from the physical layer and up the communication stack. Spectrum Sensing, Spectrum Decision, Spectrum Mobility and Spectrum Sharing, are the four functionalities involved in Cognitive Radio Networks. This paper proposes a framework for data traffic man-agement by considering the QoS requirement of the secondary user and also the primary user activity. The Location information of the primary user in cognitive radio networks can be used to assist the communication among secondary users outside the transmission coverage area of primary users and also for tracking the primary user activities. The objective of the paper is to design a framework which will support the secondary user data transmission while considering the primary user activity and QoS requirement.
