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Fundamental limits of spectrum-sharing in fading environments

Fundamental limits of spectrum-sharing in fading environments,10.1109/TWC.2007.05447,IEEE Transactions on Wireless Communications,Amir Ghasemi,Elvino

Fundamental limits of spectrum-sharing in fading environments   (Citations: 192)
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Abstract Traditionally, the frequency spectrum is licensed to users by government agencies in a rigid manner where the licensee has the exclusive right to access the allocated band. Therefore, licensees are protected from any interference all the time. From a practical standpoint, however, an unlicensed (secondary) user may share a frequency band with its licensed (primary) owner as long as the interference it incurs is not deemed harmful by the licensee. In a fading environment, a secondary user may take advantage of this fact by opportunistically transmitting with high power when its signal, as received by the licensed receiver, is deeply faded. In this paper we investigate the capacity gains ofiered by this dynamic spectrum sharing approach when channels vary due to fading. In particular, we quantify the relation between the secondary channel capacity and the interference in∞icted on the primary user. We further evaluate and compare the capacity under difierent fading distributions. Interestingly, our results indicate a signiflcant gain in spectrum access in fading environments compared to the deterministic case. Index terms: Spectrum sharing, received-power constraint, interference temperature, op- portunistic access.
Journal: IEEE Transactions on Wireless Communications - TWC , vol. 6, no. 2, pp. 649-658, 2007
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    • ...Three approaches have been developed for cognitive radio so far regarding the way a secondary user accesses the licensed spectrum: (i) the opportunistic spectrum access [5], [6], where the secondary users transmit only when a frequency band is detected to be idle, (ii) the spectrum sharing [7], [8], where the secondary users coexist with the primary users and apply an interference constraint to ensure the quality of service (QoS) of the ...
    • ...2. The channels are assumed to be flat fading and the channel power gains are assumed to be ergodic, stationary and known at the secondary users, as in [7],[9], [17],[18]...

    Stergios Stotaset al. Optimal Sensing Time and Power Allocation in Multiband Cognitive Radio...

    • ...Achievable channel capacity and rate region for secondary users were analyzed in [6], [7]...

    Ki Won Sunget al. On the requirements of secondary access to 960–1215 MHz aeronautical s...

    • ...For fading PU and SU channels, with perfect channel state information (CSI) on the channels from the SU transmitter to the SU and PU receivers, the optimal power allocation strategy to achieve the ergodic capacity of the SU fading channel was derived in [7] subject to an average/peak interference power constraint at the PU receiver...

    Xin Kanget al. Optimal Power Allocation Strategies for Fading Cognitive Radio Channel...

    • ...Coexisting systems can share the spectrum using the underlay method, which allows all systems to use the whole spectrum concurrently [6], [7], or the overlay method, which forces each system to utilize exclusively-assigned spectrum [8]–[10]...
    • ...Ghasemi and Sousa derived the capacity of a secondary system under peak and average interference constraints in fading environments [7], and Kang et al. analyzed the ergodic and outage capacity of a secondary system under a delay limitation [12]...

    Jemin Leeet al. Spectrum-Sharing Transmission Capacity

    • ...With CSI between secondary transmitter and primary receiver assumed at SU, [4] considered a single SU and a single/multiple PU and derived the optimal power allocation scheme to achieve the secondary’s ergodic capacity under a peak interference power constraint (PIPC) or an average interference power constraint (AIPC) at the PU receiver in fading channels...

    Athipat Limmaneeet al. Service-Outage Capacity Maximization in Cognitive Radio

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