Method for relay selection in cognitive radio networks

A method for relay selection within a cognitive radio network, the method being performed by a processor, the method comprising:

• identifying one or more primary source devices and primary destination devices within a primary network of the cognitive radio network;
• identifying one or more secondary source devices and secondary destination devices, and a predetermined number of cognitive relays within a secondary network of the cognitive radio network;
• transmitting data packets from the primary network for every time slot during network operation on a continuous basis;
• and
• selecting a source relay link or a relay destination link within the secondary network to transmit predetermined data based on a modified Max-Link relay selection with set criterion of
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• where RSp,Rp(1) and RSp,Rp(2) are the normalized rates of the primary network, Rs,Ri is the channel matrix for a link between source and relay i, and RRi,D) is the channel matrix for a link between relay Ri and destination D,
• wherein the one or more primary source devices, primary destination devices, secondary source devices, secondary destination devices and cognitive relays are multiple-input multiple-output (MIMO) devices,
• selecting an oldest data packet stored in the relay link and perform a modulation operation to provide a modulated data packet,
• transmitting the modulated data packet to a destination link;
• the method further comprising
• identifying a MIMO channel for transmission on a source-relay link, or a relay-destination link on the secondary network;
• dividing the MIMO channel into a predetermined number of parallel, independent, and ranked channels;
• and
• enhancing efficiency of power usage by
• allocating a transmission power budget, and
• distributing the transmission power budget among primary and secondary transmitting antenna devices at a predetermined time interval.