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Orbit > FAQ


Here you can find the answer to some of the most frequently asked questions about Orbit Testbed.  
If you cannot find answers in this list, please ask your questions at

The Orbit team is actively seeking new items to add to this list. If you would like to add an item, or have a suggestion on how to make this list more useful, please send us email at

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ORBIT Profile
What types of experiments does ORBIT support?

The ORBIT radio grid emulator is an indoor wireless network testbed. It supports experimental research on a broad range of wireless networking issues and application concepts with various network topologies and network layer protocol options.  It also support virtual mobility for mobile network protocol and application research. The ORBIT radio grid emulator currently uses 802.11x based radio cards. Some examples of systems and protocol designs that can be investigated on the ORBIT emulator grid include:

  * Large-scale wireless access networks based on 802.11a, b, g radios along with new protocols for discovery, routing, mobility management, security, etc. under various indoor and outdoor usage scenarios and network topologies.
  * Mobile ad hoc networks (MANET), typically based on 802.11x  radios, along with multi-hop ad hoc routing protocols such as AODV, DSR and new protocols.
  * Wireless sensor networks and pervasive computing applications.
  * Mobile applications such as location-based services, VoIP over MANET, mobile multicasting, etc.

In the future, the ORBIT emulator grid will support other radio interfaces such as Blootooth and allow research on heterogenerous wireless networks. It can also accommodate new technologies such as UWB as they emerge.
Can I test my new physical layer model on ORBIT?

No. Due to indoor setup constrains, the ORBIT emulator grid does not capture all radio channel effects. The radio channels for the ORBIT emulator grid will normally have no significant multipath. For physical layer radio testing, the absence of multipath would be unacceptable; however, for a wireless network testbed, the differences are less significant.  A combination of channel impairment and multiuser interference results in the failure of the physical layer to provide a reliable link so that connectivity is lost at the network layer. Using programmable interference and grid mobility, the emulator will create similar variations in network connectivity.

Can I test my new 802.11 MAC scheduling scheme on ORBIT?

Yes and No. The ORBIT radio grid emulator currently uses standard 802.11x radio interface cards with Linux drivers (Host AP and MADwifi). The drivers allow changing certain parameters such as channel, TX power, TX rate, etc. but not all. If your new MAC scheme requires 802.11 modification that is not supported by our current drivers.  We also plan to develop more flexible drivers and customized 802.11x cards in collaboration with chip and card manufacturers

How is the mobility supported by ORBIT?

The ORBIT radio grid emulator support virtual mobility. Virtual mobiles are introduced for discretized grid mobility. Physically located off the radio grid, a virtual mobile has a network driver that delivers packets to a mobility controller. Via high speed wired Ethernet, the mobility controller encapsulates and forwards these packets to a radio grid node i, which simply decapsulates and transmits each packet.  In addition, packets received by grid node i will be forwarded via the mobility controller to the virtual mobile. In short, the virtual mobile will appear to be at grid location i by using radio grid node i for transmitting and receiving packets.  It will use grid radio node j when it "moves" to grid location j. Grid mobility can support discretized versions of commonly used mobility models such as Brownian motion or the random waypoint model. In addition to virtual grid mobility, we plan on a small number of programmable mobile robots. These mobiles will communicate with the radio grid and allow experimentation with finer grain mobility experiments.

What radio parameters can I measure?

Currently, RSSI, TX_power, noise, throughput, and offered-load can be measured and collected. Users can select one or more of these parameters to be collected and stored in the database.

Getting Started

Who is eligible to use ORBIT?

As ORBIT name (Open-Access Research Testbed for Next-Generation Wireless Networks) says, almost all research or educational uses by those that have a need for it are appropriate and encouraged. These include use by universities, industrial research labs, and both US and non-US institutions. With some provisions, use for product development and evaluation by companies is also acceptable. Please email us if you are interested.

How do I start a project?

ORBIT is still under development. Please email us if you are interested in doing experiments with the ORBIT testbed. In the future there will be a web interface for the project application.

Using the ORBIT Testbed
Is there a tutorial?

Yes, it is available here.

Do I get root access on my radio nodes?
Yes. you can get root access to all of the radio nodes used in your experiments.

Do my nodes have consoles I can look at?

Yes. Each of the radio nodes has its own serial console line with which you can interact through the chasis manager (CM). In any case, all console output from each node is saved so that you may look at it later.

Can I reboot (power cycle) my nodes?

Yes. Each of the radio nodes is independently power controlled by the chasis manager. If your node hangs, or is otherwise unresponsive, you can reboort it.

Are there Linux sources and packages available locally?

Yes. We provide sources and packages for a few versions of  Linux. We are also developing software components and libriaries for experiemnt control, experiment data collection, and user application development.

Hardware Setup
How many radio nodes are there?

Currently, we will support 64 nodes in a 8*8 grid. In the near future, this will be increased to 400 nodes in a 20*20 grid

How many radio interfaces on each node?

There are two mini-PCI 802.11 a/b/g interfaces cards on each node. In addition to that, there will be USB-based Bluetooth and Zygbee interfaces.

What OS do the nodes run?
The default Operating Systems that run on each of the radio nodes is Linux (Debian GNU/Linux 3.0 with Linux kernel 2.6.4). But every experimenter can load any OS they want.

Can I run my own Operating System?

Yes, you can run your own OS (or a customized version of an ORBIT-supported OS) on any of the radio nodes. We provide infrastructure to image the nodes involved in the experiment with the provided OS image.

Can I load my own software packages on my nodes?

Yes! If have one or more software packages that are appropriate for loading on the OS you have selected, you can arrange to have them loaded automatically via APT package system when your experiment is configured. You may specify a different list of software packages for each radio node in the experiment. When the node first boots after the experiment is configured, each of the packages will be installed.

Is the ORBIT testbed firewalled?



Some interesting observations regarding wireless cards

A few interesting things for wireless experimenters in general
  * Some cards do allow you to set certain transmit power values even though they are not supported by the hardware. E.g Cisco Aironet 350 series card supports 1, 5, 20, 30, 50 and 100 mW transmit powers. However, it does not complain even if the transmit power is set to other values. We believe that it is simply rounded off to the next allowable power level
  * Not all cards allow you to change the channel. On the Cisco Aironet 350 series card, in order to change the channel, you have to create a new essid and then switch to the new channel.