Abstract
Due to the increasing spectrum scarcity in satellite communications and terrestrial communications, cognitive satellite communications have received widespread attention. In this paper, we take the inherent feature that the terrestrial cognitive users suffer from inter-beam interference. In particular, for the first time, we consider the coupling characteristics of channel access and power optimization in opportunistic spectrum access based on distributed frameworks. We first formulate a joint channel access and power optimization game, which is proven to be an exact potential game and accordingly has at least one pure Nash Equilibrium (NE) point. The sufficient conditions for interference-free between cognitive users and for maximization of system utility are given, respectively. Also, the lower bound of the system utility is deduced theoretically. For discrete power control strategies, we then propose a joint-strategy iteration algorithm (JID) to converge to the general NE in two-dimensional discrete strategy space. Especially, to solve the challenge of finding the optimal NE solution in two-dimensional strategy space, we propose a novel joint-strategy iteration algorithm based on exploration and exploitation (JIDEE). Simultaneously, these two algorithms are extended to the case where the power control strategies are continuous. Finally, simulations are conducted to confirm the effectiveness of the formulated game and the two proposed algorithms.
Highlights
With the increasing demand for broadcast, multimedia, and interactive services, satellite communications and terrestrial communications face the challenges of insufficient spectrum resources [1], [2]
As a spectrum sharing technology, cognitive radio has been extensively investigated in many fields, such as device-to-device communication [3], vehicular communication [4], unmanned aerial vehicle (UAV) communication [5], and wireless sensor network [6]
Denote the joint channel access and power optimization game as G = N, {An}n∈N, {un}n∈N, where N = {1, · · · N } is the cognitive user set, An is the strategy set of available actions for cognitive user n, An = Sn ⊗ Pn, where Sn is the strategy set of available channels for cognitive user n, Pn = pn|0 < pn ≤ pmn ax represents the power constraint of cognitive player n, and ⊗ denotes the Cartesian product
Summary
With the increasing demand for broadcast, multimedia, and interactive services, satellite communications and terrestrial communications face the challenges of insufficient spectrum resources [1], [2]. B. CONTRIBUTIONS In this paper, we investigate the interweave spectrum sharing between satellite communications and terrestrial communications, and perform distributed algorithms to optimize the system throughput. It is noted that our earlier work [27] studies the spectrum sharing in cognitive satellite communication in the interweave mode, in which only channel selection is optimized (terrestrial cognitive users are non-cooperative and always transmit with the maximum power), significantly reducing the system throughput. The algorithm proposed in [27] converges slowly and does not always converge to the optimal NE Motivated by all these observations, this work extends pure channel selection to joint channel selection and power control, which is not investigated in dynamic spectrum access based on distributed frameworks [26], [28]–[35]. To facilitate the collaboration between cognitive users, channel state information and user transmission strategies need to be exchanged between cognitive users
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