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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: Testbed 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:
 * on-boarding (console) and domain support server(s) 
 * [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])
While most of the devices in each domain are fully under user control (labeled with '''(U)''' in the architecture figure), a number of domain-level devices (labeled with '''(D)''') are providing services and can only be partially configured by the user (i.e. are deployed with restricted user access). Similarly, a number of services and devices are deployed globally (labeled '''G''' in the figure) for the entire testbed. 

COSMOS includes three types of radio nodes:
 * [wiki:Hardware/Nodes#LargeNode large] (rooftop installed "multi-sector base station" (BS))
 * [wiki:Hardware/Nodes#MediumNode medium] (building-side-mounted or light-pole-mounted "microcellular BSs")
 * [wiki:Hardware/Nodes#SmallNode small] (fixed or mobile).

Finally, 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 [[https://en.wikipedia.org/wiki/32_Avenue_of_the_Americas 32 AoA] which is also one of the main national and international interconnect location) interconnected with the high-speed optical backbone.