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= Architecture

Figure 1 presents a system view of the COSMOS testbed. It is based on a multi-layered computing system built in a bottom-up manner with commodity components, programmable hardware, and open-source software. 

The collection of global testbed services are deployed on a pair of computing clusters located at WINLAB's ORBIT facility in North Brunswick, NJ and Columbia University CS data center (CRF) in West Harlem in New York City, NY. 

[[Image(COSMOS-Architecture.png, width=800)]]
[br] '''Figure 1: COSMOS Architecture'''

These core services are supporting multiple [wiki:Architecture/Domains experimentation domains]. As is shown in Figure 1, each of the domains consists of the following components:
 * [wiki:Hardware/Nodes#Nodes SDR nodes] (user devices and radio hardware), 
 * edge cloud [wiki:Hardware/Compute servers] ("radio cloud")
 * general purpose computing cloud [wiki:Hardware/Compute servers] ("core cloud")
 * networking (both [wiki:Hardware/Optical optical] and [wiki:Hardware/Network electrical])

The core cloud for the large testbed domain (bed.cosmos-lab.org) is split across two locations in NYC: uptown CU CRF data center and downtown NYU data center at 32 AoA interconnected with the high-speed optical backbone. 

In particular, COSMOS includes three types of radio nodes:
 * large (rooftop installed "multi-sector base station" (BS))
 * medium (building side or lightpole-mounted "microcellular BSs")
 * small (fixed or mobile).