دانلود رایگان مقاله تخصیص منابع برای شبکه رادیو شناختی چندپخشی مبتنی بر OFDMA

ABSTRACT

The resource allocation problem for orthogonal frequency-division multiple-access (OFDMA)-based multicast cognitive radio networks is investigated under the spectral activities of primary users (PUs). The interactions between PUs and secondary users (SUs) are modelled using a Stackelberg game where the PUs are the leaders while the SUs are the followers. Using an efficient pricing framework, the PUs who are the licensed spectrum owners compete to lease their subcarriers to the SUs. The competition among PUs is modelled using a non-cooperative game in which they greedily adjust the pricing coefficients to harvest maximum profits while maintaining tolerable interference. Based on the pricing coefficients, the SUs autonomously form coalitions and collectively adjust their received power so as to access more subcarriers at affordable costs. Two disjoint algorithms are proposed to facilitate successful transactions between PUs and SUs so that Stackelberg equilibrium can be achieved where both the PUs and SUs can obtain maximum payoffs. Simulation results demonstrate that the proposed scheme outperforms the conventional unicast and multicast schemes in cognitive radio networks while achieving a near-optimal performance comparable to the exhaustive search scheme.

6. Conclusion

In this paper, an efficient spectrum leasing framework is proposed to model spectrum sharing between PUs and SUs in an OFDMA-based multicast cognitive radio network. An adaptive pricing mechanism is introduced for the PUs to regulate the CF and SPA among SUs so that the interference created by SUs is below the ITC. The interaction between PUs and SUs is modelled using the CSGP where PUs who are the leaders compete among themselves in the NPAG to lease their subcarriers to the SUs. Being the followers, the SUs cooperatively form coalitions in the MCGP to acquire more subcarriers at minimal costs. The pricing strategies of the PUs play a vital role in deciding the CF and SPA. It is noticed that the PUs tend to reduce the pricing coefficients if the ITC allows it because this move can improve the total profit. Besides, lower pricing coefficients also improve the net payoff of the SUs by encouraging them to form larger coalitions and use higher received power. Finally, simulation results show that the MCGP significantly outperforms the conventional schemes particularly in systems with high interference gains.