White Paper

WHITE PAPER COTS Software Defined Radio for 5G Development mrcy.com 1 1 HARDWARE Figure 8 is an example COTS SDR board used to emulate an RRH in a C-RAN system. A sub-section of the original C-RAN with the RRH is pictured on the left side of the figure and the COTS SDR RRH to the right. The "blue" encircled areas are equivalent. The custom modular carrier card (light green area) contains Rx, and Tx amplifiers, a GPS receiver, and an O/E transceiver module. The SOM (gray area) contains the RFSoC, and all the connections for power management, data storage, and analog & digital I/O. The incoming RF signal from the antenna is connected to the Rx LNA via a duplexer, isolating it from high power amplifier (PA) transmit levels, and connecting it to one A/D channel. This SOM & custom carrier combination can emulate the original RRH provided it has the necessary IP described in the next section. Ethernet/ CPRI DUC Analog Radio Ant 1 Digital Radio CFR DPD DDC/AAA DAC/ADC IF DAC/ADC Analog Front-end > > > > > > PA LNA Duplexer Radio Module 1 PL GPIO O-to-E Module SFP+ Connector Carrier Card GTY LVDS CFR Process CFR Process Power Meter IP Module Threshold Detector IP Module DDC IP Module DDU IP Module CFR Ref Signal < < < < < Sys Ref GPS Receiver Rx Amp Tx Amp Duplexer > SYSTEM-ON-MODULE SECTION > ORIGINAL C-RAN RRH Figure 8 System-on-Module RRH Substitution Example FIRMWARE Once inside the FPGA fabric the digital samples are decimated, frequency selected, or tuned, and filtered in the DDC. The DDC output samples can be streamed to the power meter module for measurement, and sorted in the threshold detector IP module. These processed samples can be streamed to the ARM processors for crest factor reduction and digital pre- distortion routines before being up-converted in the DUC for re-transmission. The DUC is the reverse of the DDC using frequency translation, and interpolation instead of decimation. The digitized I/Q sample data is packetized in the digital radio for transport to the BBU via a radio data switch as in the previous description of a cellular phone call. Because of the variety of channels and data transfer protocols it is necessary to calculate the maximum data through-put of your signal.

• Cover