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 programmable RF transceiver test system 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.

RF Node Hardware

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 connected through individual 15dB attenuators to a power combiner which connects through a single enclosure access port to the RF test system. This connection is referred to as "WiFi/WiMAX" in subsequent diagrams.

Four of the RF nodes are also equipped with USRP B205mini-i SDR devices. The TX/RX and RX2 ports are connected through individual 15dB attenuators to a 2-way power combiner which connects through the second enclosure access port to the RF test system. This connection is referred to as "USRP" or "SDR" in subsequent diagrams.

Three of the RF nodes are also equipped with USB LTE client adapters for experimentation using commercial clients. The antenna connections of the adapters are connected through individual 15dB attenuators to a 2-way power combiner which connects through the second enclosure access port to the RF test system. This connection is referred to as "LTE Client" in subsequent diagrams.

Node Name	RF Connection 1	RF Connection 2
node1-1	WiFi/WiMAX	none
node1-2	WiFi/WiMAX	none
node1-3	WiFi/WiMAX	USRP
node1-4	WiFi/WiMAX	USRP
node1-5	WiFi/WiMAX	USRP
node1-6	WiFi/WiMAX	USRP
node1-7	WiFi/WiMAX	LTE Client
node1-8	WiFi/WiMAX	LTE Client
node1-9	WiFi/WiMAX	LTE Client
node2-1	none	none

RF Test System

The RF connections of the enclosures housing the nodes as well as the antenna connections of the LTE and WiMAX base stations are all connected to the RF transceiver test system which is composed of an array of RF switches and two attenuator matrices. This system is capable of handling two completely independent topologies: one with up to 9 devices and the other with up to 5 devices, permitting a wide range of experiments to be conducted, including spectrum sharing and multi-homing. Users can configure which devices connect to which matrix and dynamically control the attenuation of each connection pair using the Instrumentation AM service.

Matrix 1:

This is a 9-way full fan-out RF transceiver test system (attenuator matrix) from ​JFW Industries.

Frequency Range: 2 - 6 GHz
Attenuation Range: 0 - 63 dB in 1 dB steps (in addition to insertion loss and losses from node enclosure connections)
Insertion Loss: 36.0 dB max (31.3 dB typical @ 2 GHz, 33.9 dB typical @ 6 GHz)

Port #	Default Connection	Alternative Connection
1	node1-1 : WiFi/WiMAX	LTE BS (LTE-03)
2	node1-2 : WiFi/WiMAX	LTE BS (LTE-04)
3	node1-3 : WiFi/WiMAX	node1-3 : USRP
4	node1-4 : WiFi/WiMAX	node1-4 : USRP
5	node1-5 : WiFi/WiMAX	node1-5 : USRP
6	node1-6 : WiFi/WiMAX	node1-6 : USRP
7	node1-7 : WiFi/WiMAX	node1-7 : LTE Client
8	node1-8 : WiFi/WiMAX	WiMAX BS (WMX-03)
9	node1-9 : WiFi/WiMAX	WiMAX BS (WMX-04)

Matrix 2:

This is a 5-way full fan-out RF transceiver test system (attenuator matrix) that was developed in-house.

Frequency Range: 0.5 - 6 GHz
Attenuation Range: 0 - 63.5 dB in 0.25 dB steps (in addition to insertion loss and losses from node enclosure connections)
Insertion Loss: TODO dB max (TODO dB typical)

Port #	Default Connection	Alternative Connection
1	LTE BS (LTE-03)	node1-3 : WiFi/WiMAX
2	node1-3 : USRP	node1-4 : WiFi/WiMAX
3	node1-4 : USRP	node1-5 : WiFi/WiMAX
4	node1-5 : USRP	node1-8 : LTE Client
5	node1-6 : USRP	node1-9 : LTE Client

IMPORTANT: A device can only be connected to a SINGLE matrix at a time (eg. you can NOT connect USRP of node1-3 to both matrix 1 and matrix 2).

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