Institute for Telecommunication Sciences / Research / Radio Access Technologies / CRAIN

Communications Research and Innovation Network

The ITS Communications Research and Innovation Network (CRAIN) laboratory supports research focused on test and evaluation of 5G, Open RAN, and future communications technologies. Lab capabilities include end-to-end 5G functional and performance testing, network slicing, and traffic loading. Over-the-air (OTA) testing can be performed in an RF shield cube, an RF shield room, or at the Table Mountain Radio Quiet Zone. CRAIN was established to provide testing capabilities for emerging 5G systems but has been designed to facilitate upgrades to 6G and beyond.  

As shown in the figure below, CRAIN is equipped with both a 4G/5G system with a Non-Standalone (NSA) core and a 5G system with Standalone (SA) core from a commercial Tier 1 5G vendor. The NSA core supports both 4G LTE and 5G New Radio (NR) operation, which is the common approach U.S.-based wireless service providers adopted to bridge between previously existing 4G LTE systems and newly deployed 5G base stations. One evolved Node B (eNB) and two Next Generation Node Bs (gNBs) from the commercial Tier 1 4G/5G vendor are deployed and can transmit in an RF screen room.

 

network architecture diagram
CRAIN network high-level architecture diagram.

 

The SA core deployment supports 5G operation and includes three remote radio heads (RRHs) operating in various frequency bands. A millimeter-wave (mmWave) system operating in the n260 band (37–40 GHz) is deployed and operational at Table Mountain. The CRAIN core also has an IMS/EVC for support of Voice over LTE (VoLTE) and Voice over New Radio (VoNR). These systems serve as a baseline network using equipment from a commercial Tier 1 5G vendor.

 

Over-the-air test setup at Table Mountain Field Site
Typical test setup for over-the-air (OTA) emissions measurements for research supported by the CRAIN lab. The mmWave gNodeB radio is mounted on the tower, a UE is placed at a specified distance from the tower in the antenna beam, and the measurement system vehicle is parked in the far field for this measurement.

 

An emulated 4G/5G core and a load generator are also deployed. Although the CRAIN Laboratory has real mobile phones (also called user equipment (UE)) from different vendors, the load generator can emulate thousands of UEs and can be used to perform load testing on both the Open RAN and the commercial Tier 1 RAN systems. Each of the RANs in CRAIN can be tested in an over-the-air setup with real mobile phones (also called user equipment, or UE) in an RF screen room or in a cabled setup with a load generator that can emulate thousands of UEs for load testing.

Development of the CRAIN laboratory began with the acquisition of a commercial Tier 1 5G wireless system to support ongoing ITS research on 4G LTE and serve as the foundation for 5G work. The first systems deployed were a commercial Tier 1 5G RAN and 5G core. To source devices to test, ITS issued a Broad Agency Announcement (BAA) to procure prototype or commercial off-the-shelf (COTS) Open RAN equipment and software. From the BAA responses, ITS selected two first-generation commercial vendors whose equipment was already available on the open market and began testing to validate these Open RAN systems in a high-performance, carrier-grade environment. Some lessons learned from this initial integration effort are reported here.