The UCR Wireless Networking Research Testbed is designed to be a static mesh network. Currently we have deployed all of our nodes in the 3rd floor of the EBU-2 campus building at UC Riverside. Each node has one or more wireless interfaces and is connected to a central server through a wired Ethernet backhaul.

Since summer 2008, with our new and flexible achitecture, each node is represented by a "device set". Each of these sets involves 3 devices: a Soekris net4826/5501, an Ettus GNU radio and a Dell Inspiron 530S PC. Furthermore, we have enriched our network with 6 WARP boards.

Our Soekris nodes are diskless. They retrieve their kernels, and mount their root file system directly from the central server. This means that every researcher can maintain his/her own, independent experimental setup, including kernel and every component of the distro. In fact, it isn't even necessary to run linux. Any small OS capable of mounting their root off NFS will work. Moreover, our Soekris nodes are powered through the Ethernet cable. This has several advantages, but the main advantage is that we have centralized control over node power. Through the use of a managed PoE switch, we can remotely power-cycle any node in the network, at our leisure. We predict that this will have a significant impact on testbed useability, as no running around will be necessary to reset hung nodes.

Each device set is connected through an Ethernet cable to a switch. The devices that constitute a set are also interconnected through a smaller switch. In what follows, we describe each hardware component; we also depict the device connectivity.

The Nodes

The node hardware specifics

Each of our nodes (device sets) is comprised of the following hardware components:

-- Soekris net4826/5501 board and case: The Soekris supports up to two mini-PCI cards. Most of our boxes contain two wireless miniPCI cards; an Atheros EMP 8602, and a Ralink RT2860 MIMO card. We use Power-over-Ethernet (PoE) throughout the testbed. With PoE, we are able to control the power supply to each node, through a managed, PoE-enabled switch. More details for the specs of this communication computer can be found in the Soekris Engineering web page. The specifications that we are mainly interested in, are the following:

SOEKRIS net4826 233/266 Mhz AMD Geode SC1100 32-256 Mbyte SDRAM soldered on board 10/100 Mbit Ethernet port 2 Mini-PCI type III sockets Power using external power supply is 11-56V DC, 12W

Be careful: We have not managed to power the board directly from the Ethernet port; so make sure you can do this. Otherwise you need the D-Link-P50 PoE adapter, that we explain below.  

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-- ETTUS USRP GNU radio: The Universal Software Radio Peripheral, or USRP, is a device which allows you to create a software radio using any computer with a USB 2 port. Various plug-on daughterboards allow the USRP to be used on different radio frequency bands. Daughterboards are available from DC to 2.9 GHz at this time. The entire design of the USRP is open source.

USRP GNU radio 12-bit 64M sample/sec ADCs 4 14-bit, 128M sample/sec DACs FPGA Programmable USB 2.0 controller

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-- WARP board: WARP is a scalable and extensible programmable wireless platform, built from the ground up, to prototype advanced wireless networks. ARP opens both hardware and software needed to research, build and prototype next-generation of wireless networks. This is enabling a community of researchers to pool their ideas in undertaking clean-slate prototype networks.

WARP board Xilinx Virtex-II Pro FPGA

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-- DELL Inspiron 530S: This is regular Dell machine that is used to connect and manage the GNU radios and the WARP cards.

DELL Inspiron 530S 250 GB hard disk 1 GB RAM

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-- Linksys EZXS55W 5-port switch: We use this small, efficient switch to connect the devices within a device set.

Linksys EZXS55W switch 10/100 dual-speed per-port auto sensing Up to 200 Mbps in full-duplex operation

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-- D-Link DWL-P50 PoE adapter: This is an external PoE splitter, used to isolate the power from the PoE supply, and forward it to a specific output, toward the net4826 board. We use this item in order to be able to remotely power on/off the Soekris boxes, without affecting the rest of the devices in a device set. This is clearly seen at a later figure that shows the device connectivity within a device set. The cool feature with this device is that even when there is no PoE enabled, the data is still travelling from the input to the output port of the device. Hence, when we decide to power off a Soekris node, the rest of the devices can still exchange data with the server and the rest of the network!

D-Link DWL-P50 Power over Ethernet splitter

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-- EMP-8602 6G miniPCI WiFi card: We are using this high-power wireless mini PCI card for the node's wireless interface. Using the latest in technology expertise, the EMP-8602 / NMP-8602 mini-PCI is the longest range and most powerful RF module on the market today.

EMP-8602 6G IEEE 802.11a/b/g * 26 dBm +/- 2dBm 802.11b * 26 dBm +/- 2dBm 802.11g * 20 dBm +/- 2dBm 802.11a Supports the MadWifi driver for linux Weight: 15g U.FL antenna connectors Input Voltage: 3.3V Support for 802.11e/i/h/j

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-- Ralink RT2860 miniPCI WiFi card: This is also a power Wifi card, which use mainly use for MIMO experiments and implementations. It has three inputs for antennas, therefore we had to drill our boxes to host the antennas. We thank Ralink Corp. for providing the Linux drivers for access points and clients. 

RALINK RT2860 802.11n draft Chipset: Ralink RT2860 MIMO Technology Mini PCI Type IIIB Backward Compatible with 802.11b/g

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-- Intel 2915abg mini PCI WiFi card: The Intel 2915 wireless cards use the flexible open-source ipw2200 Linux driver. This solution is based on the MiniPCI Type 3B form factor. We thank Intel Research for donating 29 cards and for providing the prototype Linux drivers for access points and clients.

INTEL 2915 IEEE 802.11a/b/g U.FL antenna connectors ipw2200 Intel driver, firmware WEP - 128-bit, WEP - 64-bit, WPA, WPA2 Weight 0.46 oz

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-- U.FL to Rp-SMA Pigtail: We use this pigtail to connect the wireless card with the external antenna of the node.

U.FL to RP-SMA Pigtail 7.9'' overall length 1.13 mm cable

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-- RD2458-5-RSMA Rubber Duck Antenna: This is a triBand APXtender indoor rubber duck antenna with RSMA male connector. We are quite happy with its capabilities, so far.

RD2458-5-RSMA antenna 5-dBi gain RSMA male connector

The following picture shows an assembled Soekris node, with the Atheros card only, without its cover:

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The Server

In order to be able to manage the nodes centrally and initiate experiments, we use a server, which is located in our laboratory. The server is a DELL Pentium IV at 1.8 GHz, with 768 MB or memory. The server is equipped with two Ethernet cards. One is used for the testbed VLAN connectivity, and the other for the connectivity to the outer world. The nodes are remotely accessible only through the server.

DELL P4 @ 1.8 GHz 2 10/100 Mbit Ethernet cards 768 MB SDRam CD/DVD Rom 1 Serial port

The server's hostname is "dux". Besides the server, we also use a desktop PC for building software and kernels. This Pentium III desktop PC runs the same operating system with the nodes. We use this PIII PC to compile drivers, kernels and applications used by the nodes. Moreover, for our initial experiments we purchaced a MICROTEL desktop PC for various testing procedures. (We are not using that anymore).

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The Switches

We use a set of D-Link - DES-1526 - 24-Port 10/100 Web Smart Switches. The purpose of these PoE switches is twofold. First, they connect each node to the server's Ethernet interface. This is for being able to remotely access the nodes. Second, they provide power to the nodes. In that way we are able to remotely power on/off the nodes, by enabling/disabling power support of the corresponding ports of the PoE switches. The software method is provided in our tools page.

D-Link - DES-1526 24-port 10/100Mbps 2 combo 1000Base-T/SFP 8.8G Switching Capacity Port Mirroring 64 802.1Q VLAN Groups QoS 802.3ad Link Aggregation 24 Port 802.3af PoE Web-GUI BootP / DHCP Client SNMP v.1

Each switch features 24 PoE 802.3af ports integrated into a Web-Smart switch. It has advanced features such as SNMP, VLANs, priority queuing, and port monitoring/statistics. It provides up to 15.4Watts of power injection per PoE port. BootP and DHCP are protocols used to send configuration information to a client such as an IP address, subnet mask, and default gateway. The DES-1526 supports these protocols as a client and is capable of receiving this important configuration automatically without having to be manually configured by a network administrator. Currently we are using 2 switches.

Installing a PoE switch is not a difficult task. the most difficult part is to get authorization to access the network closet. The switch will be install in the same closet as the department's switches. As soon as the corresponding ports are connected, the installation is finished. The switches that we have so far are equipped with a web interface. In order to access it, one has to connect a machine to the testbed network, and use a web client. The web interface provides very useful information, such as e.g. which ports are enabled, and how much power each port consumes. Moreover, through the web interface one can set the IP of the switch.

By default the switch's IP is 192.168.0.1. In order to change this, one has to connect a machine to the testbed, and set the IP of this machine to be the latter one. Further one can change the IP of the switch to the preferable one. There may be times where the IP of the switch is automatically set to be the default one - 192.168.0.1 (e.g. perhaps after a power outage). You need to follow the above steps, in order to change it again. This is of course necessary only if you care contacting the switch now and then (e.g. in order to reboot the nodes).

From the description of the nodes, the server and the switches, it is easy for one to understand how a node is connected to the server. This is depicted in the figure below.

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The Ethernet-Fiber converters

The switches have been installed in the department's network closets, together with the department's switches. These network closets - rooms can communicate vertically between floors, but not within the same floor. As an example, the 3rd and 4th floor network closets in the faculty wing of the building can communicate with regular network cabling. However, the two network closets in the 3rd floor cannot communicate with regular network cabling. Luckily for us, there is connectivity through fiber optics. As a consequence, in order to connect two of our swiches that are placed in the 3rd floor (in the two isolated network closets), we need Ethernet to Fiber converters.

For this, we use two CVT-100BTFC(SM-30) Media Converters, one for each switch. These converters are fully compliant with the IEEE 802.3 and 802.3u Fast Ethernet standards and feature one STP-RJ45 10/100Base-TX port as well as one Fiber Optic 100Base-FX SC port. Each unit is powered by an external power supply. Installation of the Fast Ethernet converter is simple and straightforward.

CVT-100BTFC 10/100Mbps Auto Negotiation Auto cross over for TP port Support Link Alarm Support Switch mode & Pure converter mode Dual Port 10/100Mbps Switch inside Voltage supervisor

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Cabling

The cabling that we use for the testbed involves mainly cat-6 patch network cables. For convenience, we use 7ft black cables in the network closets. The cat-6 patch cables that we use to install nodes in rooms do not have a specific color or length.

Also, for connecting the switches we use Single Mode SC Duplex Cables.