Cooperative relaying using USRP and GNU radio

Abstract

Wireless communication systems have shown a tremendous development in recent years. New technologies are born day to day. With today's technology, users can communicate with each other from any corner of the world. But wireless technologies are often prone to various effects like multipath fading, interference, low signal strength, reduced spectrum efficiency etc. which makes this system less reliable. Because of this reason, researchers are continuously working to develop technologies that can make the performance of a wireless system much better. Cooperative Communications is one of the fastest growing research technologies that can enable efficient spectrum usage and create a reliable network. In traditional networks, the physical layer is only responsible for communication in between two nodes which are more hindered to the challenges of the network. Cooperative Communication creates an extra communication with the help of a Relay in between the terminals which thereby enhances the signal quality. We implement this strategy using GNU Radio and three Radios (USRP-Universal Software Radio peripheral) which act as a Transmitter, a Receiver and a Relay. Our main goal is to verify the communication in between the two Radios (a Direct Link) and implement Cooperative communication by introducing a Relay in between the two radios. The Relay is made to operate on Amplify & Forward and Decode & Forward scenarios. Characteristics like packet error rate (PER), bit error rate (BER) and character error rates are studied with respect to individual scenarios and overall bit error rate (BER) of the system is calculated. Then performance is compared against different scenarios dealing with obstructions, transmit and receive gains, and relaying approaches with the goal of determining which approaches are best in which scenarios.