||Ever since entering the age of information and communications, the IT industry has grown exponentially. Due to the growing demands for wireless communications, spectrum has become more precious. However, we find that although most of the bands have been allocated, the efficiency of spectrum usage is not optimal. Therefore, we need a smart wireless communication system, for example, Software-Defined Radio (SDR), in which silicon IP and DSP are implemented to enable spectrum sensing, spectrum management, and spectrum space allocation.|
First in this thesis we introduce an intelligent wireless system (i.e., SDR), and development of Cognitive Radio (CR). Although in recent years SDR architecture was first proposed, followed by development of CR, in fact, the concepts of CR had been applied when the radio was just invented. In introduction, two examples of CR are cited.
In the next chapter, we focus on introduction of 4G/5G, LTE-U (U for Unlicensed) and LAA (License-Assisted Access). In 4G, Carrier Aggregation (CA) technique has been implemented on licensed bands for the purpose of higher data rates. In 5G, the CA technique will be applied for both licensed and unlicensed bands. In Chapter 3 we implemented a dual-band signal receiver system on a SDR hardware by National Instruments (NI) for the signals. In addition to receiving and monitoring the dual-band signals in air instantly, the system also estimates MCS (Modulation and Coding Scheme) and throughput from RSSI, and spectrum efficiency for the individual bands. Finally, we compare the result with actual throughput test by a phone’s app.
Following the dual-band receiver system developed in previous chapter, we carry out carrier aggregation scheme and transmit the aggregated signal by switching from receiving port to transmitting port in Chapter 4. After the transmission, the SDR resume the CR mode.