Novel Real-Time Decision-Based Carrier Tracking for Software-Defined Radios Using M-ARY QAM Modulation

1. Introduction

SDR refers to the technology where software modules are designed and run on a generic platform made up of digital signal processors and many general-purpose microprocessors used to employ different radio functions like modulation (generation of signal to be transmitted) at the transmitter and demodulation (tuning/detection) of the received signal at the receiver (Yarkan 2015). A wide range of radio applications including the wireless local area network (WLAN), global positioning system (GPS), Bluetooth etc. can be implemented using the SDR technology (Javornik et al., 2005). With the new development of different ways and means by which people communicate (Mitola et al., 1999). SDR technology brings flexibility in the system, cost efficiency, multi-user communication. SDR provides so many benefits to the end-user realized by service providers and product developers (Tribble, 2008). SDR system has the capability of replacing traditional hardware which is still in common use like the FM radio or TV transmission as it can adapt to a variable environment for many different applications (Adachi & Parsons, 1989). SDR system offers a very promising futuristic technology that reduces the hardware cost as it can replace systems like FM radio or TV broadcast and cellular communication systems (Moir & Pettigrew, 2014). SDR system is an advantageous, adjustable and future-proof solution to deploy both existing and emerging standards (Sampaio, Gomes, & Santos, 2012). An SDR system provides reconfigurability, intelligence and capability to program hardware with software upgrades (Mitola, 1999). Moreover, it can provide global seamless connectivity and also provides the solution to interoperability (Note & Advanced, 2005). In a nutshell, SDR is a technology that offers multi-mode, multi-modulation reconfigurable and future-proof environment.

The proposed SDR transceiver system can be used in real-time conditions for the transfer of the data in different forms such as binary codes or text and image. As the proposed system uses M-QAM for modulation of the data it shows a better performance for lower modulation order whereas the out gets inferior as we move to a higher order of ‘M’. The proposed system uses FEC codes makes the system more secure and future-ready. The proposed SDR transceiver system uses decision-based carrier tracking which ensures that phase tracking routine, the phase error, affected by the initial phase and frequency difference, is minimized and the received signal becomes a perfect reproduction of the transmitted signal except for the time delay. The biggest advantage of the proposed SDR transceiver system is that it is built as a reconfigurable system that can perform real-time signal processing. The proposed SDR transceiver system is generic in nature and offers a low-cost solution for secured transmission of data in real time. As the proposed SDR transceiver system runs on a generic platform it is easier to optimize the processing of the signal/data. In the proposed generic SDR transceiver system the complete processing of the Signal/data has been successfully performed through software. The dedicated hardware’s used for testing the performance of the proposed SDR transceiver system; perform only the down conversion and digitization of a wide band of the RF spectrum. The proposed SDR helps to exploit the flexibility of signal/data processing through software thus helping to realize a system which could be modified dynamically at any stage through software.