Power allocation, bit loading and sub-carrier bandwidth sizing for OFDM-based cognitive radio

Efficient Power Loading in MIMO-OFDM Based Cognitive Radio Networks

Due to their spectrum shaping capability and high adaptability, the multi-carrier systems are considered as prime candidates for use in the Cognitive Radio (CR) networks. In these structures, the deactivation of the primary users’ (PUs) bands makes the secondary users (SUs) use a limited number of sub-carriers, so the total capacity of CR networks is reduced. However, multiple transmit antennas...

X Power Allocation in OFDM-Based Cognitive Radio Systems

Power Allocation in OFDM-Based Cognitive Radio Systems

In this thesis, we develop an subcarrier transmission suboptimal power allocation algorithm and an underlay subcarrier transmission optimal power allocation algorithm for the orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems with different statistical interference constraints imposed by different primary users (PUs). Given the fact that the interference constr...

Resource Allocation for OFDM Systems Based On Sub-Carrier Pairing

Orthogonal Frequency Division Multiplexing (OFDM) is a form of multicarrier modulation. Different symbols are transmitted over different subcarriers. The use of relays increase the coverage area, improve spectral efficiency and also the network lifetime. On the basis of the amplify and forward relaying mode, a two hop multi relay system is proposed with joint relay selection, subcarrier assignm...

Adaptive Subcarrier Allocation and Bit Loading for Multiuser OFDM Systems

This paper proposes a new algorithm of adaptive subcarrier allocation and bit loading for simultaneous voice and data transmission in multiuser OFDM systems. The algorithm dynamically assigns the number of subcarriers and bits/per symbol on each subcarrier for each user in a single cell. To cope with the stringent delay requirement of voice service, the subcarriers with low channel gains are as...