Cost-Effective Testbed for Cognitive Long-Range Communications based on Antenna Array and Software Defined Radio

Main objective of this work is to design and implement a cost-effective testbed for cognitive long-range communication system based on a high gain planar antenna array and Software Defined Radio (SDR) kits. Antenna integration, miniaturization and feeding network optimization have been properly executed for designing a 4x4 linear antenna array in order to achieve a return loss of -25 dB and a directivity of 19.04 dB at 2.4 GHz with a bandwidth of 18.5 MHz. Primary cognitive communication link has been established based on a Frequency Hoping (FH) scheme in the transmitter and receiver sides integrated with an energy detection spectrum sensing block, which enables the receiver seeking the operating frequency of the transmitter and synchronizing with it. Finally, a real-world testbed has been implemented using SDR units to transmit and receive text messages properly. This designed testbed can achieve a Point to Point (P2P) link of about 20 Km based on a cheap SDR with a sensitivity of -75 dBm and a 10 dBm transmitting power.