Abstract
In this article, we analyze the packet transmission time in spectrum sharing systems where a secondary user (SU) simultaneously accesses the spectrum licensed to primary users (PUs). In particular, under the assumption of an independent identical distributed Rayleigh block fading channel, we investigate the effect of the peak interference power constraint imposed by multiple PUs on the packet transmission time of the SU. Utilizing the concept of timeout, exact closed-form expressions of outage probability and average packet transmission time of the SU are derived. In addition, employing the characteristics of the M/G/1 queuing model, the impact of the number of PUs and their peak interference power constraint on the stable transmission condition and the average waiting time of packets at the SU are examined. Moreover, we then extend the analysis for point-to-point to point-to-multipoint communications allowing for multiple SUs and derive the related closed-form expressions for outage probability and successful transmission probability for the best channel condition. Numerical results are provided to corroborate our theoretical results and to illustrate applications of the derived closed-form expressions for performance evaluation of cognitive radio networks.
Highlights
Radio spectrum is one of the most precious and limited resources in wireless communications
It should be noted that the results for the average transmission time matches exactly with our previous results reported in [, Fig. ] where we considered the special case of only a single primary users (PUs) being present, i.e., M =
The results shown in Figure enable us to study the impact of the number of PUs on the average transmission time of packets at the secondary user (SU)-Tx
Summary
Radio spectrum is one of the most precious and limited resources in wireless communications. In relation to the delay constraint in the spectrum sharing system, in [ , ], we have used another approach, which is based on the packet transmission time to investigate the performance of CRN These results have revealed the impact of the peak interference power constraint on the delay of packets for different types of fading channels. 2.2 Point-to-multipoint scenario In this scenario, we consider a spectrum sharing system as shown in Figure in which a secondary base station (SBS) transmits a common packet to a number N of SU-Rx in its coverage range. . Peak interference power constraint In this spectrum sharing scenario, the power allocation problem becomes more complicated as the SBS must adjust its power to guarantee successful packet transmission to all SU-Rx in the secondary system but must limit the interference power caused to the active PU-Rx in the primary system. The SBS may not transmit the common packet successfully to all SU-Rx due to the fading environment
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