Design and implementation of a Multi-Terminal Channel Emulator on LTE TestBed

Abstract

The radio channel is a critical but independent element affecting a wireless communication system. It is highly time-varying and exhibits behaviors such as path loss, shadowing, multi-path fading and Doppler spread. In this paper, we discuss the design and implementation of a real-time Multi-Terminal Channel Emulator on an SDR (Software Defined Radio) platform for providing controlled variability of channel conditions to test wireless systems. The system design is split into three functions: (i) Channel generation on a PC (ii) Ethernet handling on a DSP (Digital Signal Processor), to receive the channel coefficients and update filters on an FPGA (Field Programmable Gate Array) and (iii) Application of the channel to the data on the FPGA (convolution). We propose a simple technique, where the unit can be used to emulate multiple user scenarios by just modifying the channel generation on the PC. This enables a single hardware unit to emulate multiple users with independent channels.