Mutual interference considered power allocation in OFDM-based cognitive networks: the multiple SUs case

• Published in: Annales des télécommunications Vol. 65; no. 7-8; pp. 341 - 351
• Main Authors: Zhao, Chengshi, Zou, Mingrui, Kwak, Kyungsup
• Format: Journal Article
• Language: English
• Published: Paris Springer-Verlag 01.08.2010; Springer
• Subjects: Applied sciences; Circuits; Communications Engineering; Computer Communication Networks; Engineering; Exact sciences and technology; Information and Communication; Information Systems and Communication Service; Information, signal and communications theory; Multiplexing; Networks; Operation, maintenance, reliability; R & D/Technology Policy; Radiocommunication specific techniques; Radiocommunications; Signal and communications theory; Signal,Image and Speech Processing; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; OFDM; Cognitive radio; Water-filling; Power allocation; Performance evaluation; Iterative method; Algorithm; Constrained optimization; Simulation; Optimal allocation; Orthogonal frequency division multiplexing; Conflict theory; Service quality; Software radio
• ISSN: 0003-4347; 1958-9395
• DOI: 10.1007/s12243-009-0140-z

Power allocation for secondary users (SUs) in cognitive networks is an important issue to ensure the SUs’ quality of service. When the mutual interference between the primary users (PUs) and the SUs is taken into consideration, it is wanted to achieve the conflict-free power allocation while synchronously maximizing the capacity of the secondary network. In this paper, the optimal power allocation problem is considered in orthogonal frequency division multiplexing cognitive networks. The single SU case is primarily formulated as a constrained optimization problem. On this basis, the multiple SUs case is then studied and simulated in detail. During the analysis, the mutual interference among the PUs and the SUs is comprehensively formulated as the restrictions on the SU’s transmission power and the optimization problems are finally resolved by iterative water-filling algorithms. Consequently, the proposed power allocation scheme restrains the interference to the primary network, as well as maximizing the capacity of the secondary network. Specifying the multiple-SUs case, simulation results are exhibited in a simplified scenario to confirm the efficiency of the proposed water-filling algorithm, and the influence of the mutual interference on the power allocation and the system capacity is further illustrated.