Wireless Mesh Networking

Self-Healing, Self-Discovery and Resilient

Robert Morris
January 23, 2014

Executive Summary

Everyone is familiar with wireless or Wi-Fi networks. We use them at home, at work or at the local coffee shop to surf the internet, access web services, generate emails, manage data, and conduct VoIP-based voice and video calls and so on. Wi-Fi even allows us to use our mobile phones to make calls and save our precious cellular minutes. What can further improve this experience? The answer lies in the next evolution of Wi-Fi, which is referred to as “mesh networking.”

Although mesh networking technology and related hardware products have been around in some form since 2006, its early use was specifically for military applications. That has changed, however, as it is becoming a more prevalent technology for consumer and business applications. Manufacturers of traditional Wi-Fi equipment are now actively developing mesh-enabled Wi-Fi systems and start-ups are also entering this arena, as both see the significant growth potential with this market. The focus of this article is on wireless mesh networks.

So, What is It?

Mesh networking is a data communications networking system that consists of numerous nodes that act as access points. Each node in the system communicates with nodes adjacent to it. These interconnections allow the mesh network to be highly resilient and self- healing. So, for example, if one of the nodes or communication routes fails, the network’s software protocol automatically reroutes the data so that it arrives at the destination. Mesh networks can be set up as hardwired or wireless.

In hardwired networks, all of the nodes are physically connected to one another by Ethernet cables so the cost of such a system is relatively high and therefore not optimal. An example of a hardwired mesh network is the traditional router network used in internet-based communications.

However, if we take the same model but now make it wireless, we end up with a resilient network that is easier to set up, manage and maintain, and which is inexpensive to implement and operate.

Nodes are an essential component of a wireless mesh network. They include access points that not only receive and transmit a data signal, but that intelligently route the data signal to an adjacent wireless node. A wireless mesh network consists of an arrangement of these nodes with generally only one or several nodes in the wireless network being hardwired- connected to the internet or hardwired network access point. You can almost think of the mesh nodes as mini cell towers, but operating on an unlicensed spectrum. A user would connect to the wireless mesh network using a device such as a Wi-Fi enabled PC or laptop, cell phone, tablet or other wireless device.

The principal difference between a wireless mesh network and a traditional Wi-Fi network is that a wireless mesh network requires specialized software and hardware that conforms to IEEE standards so its access points/nodes are able to intelligently route the data packets to adjacent nodes. In a traditional Wi-Fi network, intelligent routing between nodes is not the norm. Data from the user’s device would be received by the closest access point or node. With intelligent routing protocols, the node would determine where the data needs to be transmitted in order to reach its destination. The data packet would hop along the various nodes until it arrives at its destination. The destination could be another user on the network, another network or internet access.

Standards

The speed and capacity of wireless networks continues to increase due to improvements in the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standards on wireless connectivity. 802.11 is a set of IEEE standards on Wi-Fi communications that are appended with a letter to designate a newer standard. Prior versions include 802.11 "b", "a", "g", and “n” and the most recent "ac." Each new version or variant is an improvement from the prior with increased data throughput, speed, different frequency ranges and better use of spectrum. They are also backward compatible. Version “n” introduced MIMO or Multiple In, Multiple Out.

MIMO is the use of multiple receiving and transmitting antennas on the Wi-Fi access point; an access point could have two to four transmitters and one to four receivers. The use of multiple antennas allows the access point to reduce interference and clearly receive and transmit the Wi-Fi signals. This increases the data throughput and range without needing additional bandwidth and transmitted power.1

The newest member of the 802.11 standard is 802.11 ac, which was introduced in 2013 as a draft, with the final version expected in 2015.2  Although the standard remains in draft, OEMs have been producing compatible products for market. A 2011 study indicated growth in the “ac” market from zero units in 2011 to over 1 billion by 2015.3 “ac” is designed to operate faster and has a greater bandwidth than “n,” but like “n,” it also incorporates MIMO. The faster speed, greater bandwidth and MIMO capability of “ac” based products results in mesh networks that can handle more users and greater traffic/data loads (i.e., video downloads and uploads).

Although mesh capability has been present to varying degrees in prior variants of the 802.11 standard, the “n” and “ac” standards, with their ability to handle MIMO, faster speed and greater bandwidth, will be driving the adoption of mesh-based wireless networks.

How it Operates?

A mesh network has several key features:

  • Multi-Hop - The mesh nodes are programmed with software that instructs them how to interact within the network as the information is transmitted across the network by “hopping” wirelessly from one mesh node to the next. The multi-hop mesh eliminates the requirement for a direct line of sight link from the wired location to each node in the mesh. The nodes can automatically choose the quickest and safest path in a process known as dynamic routing.
  • Self-Healing - To ensure the path’s availability, a routing network uses “self-healing” algorithms to allow continuous operation of the network when one node breaks down or a connection is lost. This makes the wireless mesh network very reliable because there is almost always more than one path between a source and its destination in the network.
  • Self-Discovery or Organizing – Mesh protocols allow for the discovery and subsequent integration of new nodes or devices into the mesh network. This makes such networks highly scalable – they can be readily increased in size and capacity to handle additional users and traffic by simply adding nodes to the network.

Nodes are typically installed outdoors and can be mounted low on fixed objects such as a telephone pole, the roof of a building or even on a portable stand if a temporary mesh network needs to be installed. Outdoor nodes are encased in a weatherproof enclosure and require simple power supply such as traditional AC plugs, batteries or possibly a solar panel. The network connection can be spread among dozens or even hundreds of wireless mesh nodes that communicate with each other to share the network’s limited hardwired connections.

As noted, within a mesh network nodes use adjacent nodes to pass a data signal. Adding a node next to the most remote node in the network increases the geographical size of the network, which broadens its range and results in a better user experience. The limitation on a network’s geographic span is dependent on the nodes’ bandwidth capacity, signal strength based on their spacing, and the backend controller that manages this data traffic.

A visual representation of internal and external nodes and how they form a mesh network is noted below: 4

 

Advantages of a Wireless Mesh Network

In a traditional wired or fixed wireless network, all of the access points need to be hardwired to have access to the internet or another network. Hardwiring may consist of Ethernet cables that have been installed in the ceilings and walls of a building. With a wireless mesh network, only one node would need to be physically wired to a network connection like a DSL internet modem. The one wired node would then share its internet connection wirelessly with all the other mesh nodes in the vicinity. This could allow a wireless mesh network to serve an office building, an entire college campus, large cities and even temporary venues such as a large construction project or a multiday concert where the mesh nodes could be installed, moved around as needed and removed when the event is completed. Other advantages include:

  • Reduced upfront cost since fewer wires/cabling are used to set up a network.
  • Suitable for areas where Ethernet connections are not available throughout, such as a large outdoor venue used for concerts, sporting events or conventions or in developing countries that do not have a widespread, established wired infrastructure.
  • Can be used in areas where physical wires are not desired such as hotels and airports or in historic landmarks, where a wiring installation may not be allowed.
  • Rely on existing Wi-Fi standards that are already in place for most wireless networks.
  • Self-discovery capability and can automatically incorporate a new node or device into the network eliminating the need for adjustments by a network administrator.
  • Mesh networks are self-healing, so they automatically find the fastest and most reliable paths to send data, even if a node is blocked or loses its signal.5

Applications

Wi-Fi mesh networks can be found in a variety of areas such as:

  • Military – Communications system on bases.
  • Commercial/Business/Educational – Community Wi-Fi systems using mesh networks to provide Wi- Fi service throughout remote areas of the campus or commercial facility.
  • Utilities/Oil and Gas – Plant-wide communications systems for SCADA/ICS (industrial control systems). Readings from valves and sensors can be transmitted over the network to a central office.
  • Home – Security systems with Zigbee-based sensors (i.e., door contacts, motion detectors) that use a mesh system to communicate sensor status to the main panel.
  • Internet Backhaul – In rural and developing countries, rather than laying fiber or cable for internet access, companies are using Wi-Fi enabled, mesh nodes to provide internet access to areas located far away from the actual internet access point. This is significantly less expensive and more efficient than a hard line system.
  • Municipal - One of the principal applications of mesh networks has been municipal wireless networks. Beginning around 2007, many cities in the U.S. installed a mesh network system that provided their citizens, government, businesses and visitors wireless access to the internet virtually anywhere in the municipal area. Some of the more familiar cities that have a mesh network system are Scottsdale, AZ; Miami Beach, FL; Minneapolis, MN; and Corpus Christi, TX. These municipal networks use outdoor routers (nodes) installed on telephone poles, roofs and other lower elevation fixed objects with the operator of the network acting as a wireless internet service provider.6

In Scottsdale, Arizona7 a wireless mesh network was deployed in 2013 as part of the city’s “intelligent transportation system” (ITS) to deal with local traffic problems. The ITS communications platform connects wirelessly to 86 pan-tilt-zoom cameras, traffic signal controllers and dynamic message signs on arterials throughout the city so traffic can be monitored from a central command center. The cameras are strategically placed on traffic signal poles at intersections throughout Scottsdale and connected to the city’s network via Firetide wireless mesh nodes. The network can support up to 15 consecutive links or “hops” so it can easily be routed around buildings and trees rather than requiring giant 300 foot towers to operate above these obstacles. On a real-time basis, the city can monitor cameras to identify congestion, control traffic lights and send out emergency personnel or traffic wardens to clear bottlenecks that may occur when there is an accident or a special event.

The benefits of the ITS are:

  • The signal timing of the traffic lights can be adjusted to reduce traffic delays due to a collision, spills or stalled vehicles.
  • Roadway safety is improved by the immediate detection and reporting of incidents to police, emergency services, media agencies and the public.
  • Travel times can remain consistent or even be reduced.

Future Applications

As technology continues to evolve and improve, Wi-Fi mesh applications will increase and become more mainstream. A few examples include:

  • Community Mesh Networks – Microsoft researchers are adapting Wi-Fi mesh networking to create a wireless technology that allows neighbors to connect their home networks together to form a community mesh network. The vision is for a group of neighbors to cooperate and act as a node, thereby forwarding each other’s packets and eliminating the need for individual internet gateways. The packets would dynamically find a route, hopping from one neighbor’s node to another to reach the internet through one of the distributed gateways. The community mesh network could be used to distribute relevant information to the local community such as crime alerts, community events, etc. Issues that need resolving before this becomes a reality include capacity, range, privacy, security and bandwidth/usage fairness.8
  • Military - The U.S. Military originally helped develop wireless mesh networks for their applications. They now envision dropping thousands of microchip-size mesh nodes onto a battlefield to set up instant scouting and surveillance networks that can route information to ground troops and headquarter personnel.
  • Vehicle Entertainment and Safety - Mobile mesh networks will offer upgrades for in-car entertainment options such as digital music and movie downloads and can also improve driver safety. A person’s vehicle could be used as a node that could connect with other nearby vehicles to form a constantly changing mobile mesh network that helps a driver avoid accidents, identify traffic jams and act as a relay point for internet access.9

Conclusion

Consumers, businesses and government agencies continue to demand faster, more reliable communications networks and at a lower cost. Wireless mesh networking is the ideal technology to make this possible. The ability to use unlicensed spectrum and readily set up large scale, mobile Wi-Fi networks, to use Wi-Fi as an internet backhaul in developing countries and rural areas, and to build network systems that improve personal safety are just a few of the beneficial applications of a wireless mesh network. Further improvements that increase the speed, capacity and range of a wireless mesh network could truly result in global connectivity that would allow readily connecting with anyone in the world at anytime from anywhere.

Contact Us

To learn more about how OneBeacon Technology Insurance can help you manage online and other technology risks, please contact Dan Bauman, Vice President of Risk Control for OneBeacon Technology Insurance at dbauman@onebeacontech.com or 262.966.2739.

References

1 Wikipedia – MIMO: Online. Internet, Accessed 9/20/2013, http://en.wikipedia.org/wiki/MIMO

2 Phiper, Lisa; “Get Ready for Gigabit Wi-Fi.” Information Week (11/28/2012): Online. Internet. Accessed 9/20/2013, http://www.networkcomputing.com/government/get-ready-gigabit-wi-fi/1503966815

3 Burt, Jeffrey; “1 Billion 802.11ac WiFi Devices to Ship in 2013.” eweek.com (2/8/2011): Online. Internet. Accessed 9/20/2013, http://www.eweek.com/c/a/Mobile-and-Wireless/1-Billion-80211ac-WiFi-Devices-to-Ship-in-2015-InStat-776091

4 https://www.canfone.com/business/wireless/wifi-citywide-mesh-network/

5 How Stuff Works – Wireless Mesh Networking: Online. Internet, Accessed 9/20/2013, http://computer.howstuffworks.com/how-wireless-mesh-networks-work1.htm

6 “Evolution of Municipal Wireless Networks.” Cisco: Online. Internet. Accessed 9/20/2013, http://www.cisco.com/en/US/prod/collateral/wireless/ps5679/ps6548/prod_white_paper0900aecd8057255d_ns621_Networking_Solutions_White_Paper.html

7 “Scottsdale, Arizona sets up wireless mesh network to relieve traffic congestion.” Muniwireless.com (July 2, 2013): Online. Internet. Accessed 9//20/2013, http://www.muniwireless.com/2013/07/02/scottsdale-wireless-mesh-network/

8 “Self-Organizing Wireless Mesh Networks.” Microsoft Research: Online. Internet. Accessed 9/20/2013, http://research.microsoft.com/en-us/projects/mesh/

9 Fitchard, Kevin. “Ford investigates creating a mobile data network using the cars themselves.” (August 10, 2011): Online. Internet. Accessed 9/20/2013, http://www.forbes.com/sites/jimgorzelany/2011/08/12/ford-looks-to-wi-fi-to-ease-traffic-congestion-and-make-roads-safer/#54fe87b13c38