Spectrum management has been identified as a crucial step towards enabling the technology of a cognitive radio network (CRN). Most of the current works dealing with spectrum management in the CRN focus on a single task of the problem, e.g., spectrum sensing, spectrum decision, spectrum sharing or spectrum mobility. In this two-part paper, we argue that for certain network configurations, jointly performing several tasks of the spectrum management improves the spectrum efficiency. Specifically, our aim is to study the uplink resource management problem in a CRN where there exist multiple cognitive users (CUs) and access points (APs). The CUs, in order to maximize their uplink transmission rates, have to associate to a suitable AP (spectrum decision), and to share the channels used by this AP with other CUs (spectrum sharing). These tasks are clearly interdependent, and the problem of how they should be carried out efficiently and in a distributed manner is still open in the literature. In this first part of the paper, we focus on the problem of spectrum sharing in a multi-channel CRN with a single AP. The insight gained from the analysis of this simpler network is used as the building block for analyzing the multiple AP network in the second part of this paper. We formulate the single AP spectrum sharing problem into a non-cooperative power allocation game, in which individual CUs aim at maximizing their transmission rate by finding the suitable power allocation on the available channels. Interestingly, we discover that the set of equilibrium solutions of this game possesses the following optimality properties: 1) any equilibrium solution is the optimum input power allocation scheme in the sense that it maximizes the sum rate of the network if joint decoding at the AP is employed; 2) asymptotically, when the number of channels becomes large, any equilibrium solution becomes a Frequency Division Multiple Access (FDMA) strategy, and the maximum system sum rate is achieved without joint decoding. We subsequently propose a set of algorithms for the CUs in the network to achieve such equilibrium solutions in distributed fashion.
Clearly for a fixed system wide CU-AP association, the entire network is reduced to multiple single AP sub-networks, and the (near-) optimal spectrum sharing solution for each of the sub-network is studied in the first part of this paper REF .
Distributed Uplink Resource Allocation in Cognitive Radio Networks -- Part I: Equilibria and Algorithms for Power Allocation
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Mathematics Computer Science