SB4

Sandbox 4 consists of 10 nodes along with two LTE and two WiMAX base stations with corresponding BS controllers. The RF connections of these nodes and base stations are wired using low-loss coax cables to a set of RF switches and two programmable RF transceiver test systems (attenuator matrices) for controlled and repeatable experimentation using various topologies.

Nine of the nodes are equipped with wireless hardware, while the remaining one (node2-1) is intended as an ethernet only device for CUDA processing. To prevent interference, each of the 9 RF nodes is housed in its own ​Ramsey Electronics RF enclosure that provides 80 dB of isolation.

Each of the RF nodes is equipped with a pair of WiFi devices: one Atheros 5000X mini-PCI card and one Intel 6250 mini-PCIe 802.11/802.16. The antenna connections of these wireless cards are

Of these, 4 are also equipped with USRP B205mini-i SDR devices. Additionally, there are 3 nodes with All of the antenna ports of in each node are connected to a power combiner and fed through the enclosure access port to the outside SMA connector which is wired to one of the input/output ports of the ​RF Transceiver Test System from ​JFW Industries. This configuration enables fairly tight control of RF attenuation matrix between the nodes. Four of the RF test system ports are shared between nodes and basestations (node1-1 and node1-2 are sharing their port with LTE baestations while node1-8 and node1-9 are sharing their ports with WiMAX basestations). The topology (including pairwise attenuation between ports and selection switches for node/basestation) is controlled through the ​OMF based Instrumentation AM.

As can be seen in figure 1, there are a total of nine (9) input/output ports on the transceiver test system. The first 7 input/output ports are connected to nodes 1 thru 7, respectively while the 8th and 9th input/output ports are connect to either nodes 1-8 and 19 or the two Wimax base stations (BS1 and BS2). The selection of devices attached to ports 8 and 9 is controlled by the selDevice command of the Instrumentation AM service.

RF Test System Port	Attached device
1	node1-1
2	node1-2
3	node1-3
4	node1-4
5	node1-5
6	node1-6
7	node1-7
8	node1-8 or wimax BS1
9	node1-9 or wimax BS2

This configuration creates two distinct set of RF paths that are used to create various topologies.

Node to Node RF Path

s12 parameters taken with Agilent ENA RF Network Analyzer E5070; instrument dynamic range of 110 dB limits the accuracy of large attenuation results.

Node to WiMAX basestation RF Path