History of wireless mesh networking - AbsoluteAstronomy.com

The core advantage of wireless mesh networks is their inherent ability to form a network on power up. Watch what happens in Fig 1, when the mesh nodes power up (green LED on box turns on). The nodes hear each other's broadcast and form a network. Also watch what happens when a node fails and how the nodes discover an alternate routing path. This healing is fully automatic.

Over the years, wireless mesh networking has seen three unique deployments based on radio technology, each incorporating iterative improvements allowing for greater scalability

Scalability

In electronics scalability is the ability of a system, network, or process, to handle growing amount of work in a graceful manner or its ability to be enlarged to accommodate that growth...

and higher network performance - both throughput

Throughput

In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...

and latency

Latency (engineering)

Latency is a measure of time delay experienced in a system, the precise definition of which depends on the system and the time being measured. Latencies may have different meaning in different contexts.-Packet-switched networks:...

. This early stage of pre IEEE standard technological development is known as first Generation of Wireless Mesh. The following deployments are briefly described of various configurations of first generation Wireless Mesh Networking:

Winrich Hoseit of Cologne, Germany first described the "DIRC technology" (digital inter relay communication) with PCT patent No. DE 197 37 897 and DE 197 33 586. Because transmitted radio waves always interfere, the ratio of carrier to interference first had to be worked out. Hoseit also discovered how to prevent latency by transmitting single symbols rather than digital packages. (symbol stream switching). Each node collaborates with its neighbor-nodes via a control channel (CCH) to choose the frequency, time and energy with which to transmit each symbol. Only the final destination "understands" the application with the lowest possible latency.

1-Radio Mesh

As shown in Figure 3, this configuration uses one radio

Radio

Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

channel both to service clients and to provide the mesh routing path back to a wired or satellite link (backhaul

Backhaul (telecommunications)

In a hierarchical telecommunications network the backhaul portion of the network comprises the intermediate links between the core network, or backbone, of the network and the small subnetworks at the "edge" of the entire hierarchical network...

). The single mesh radio, provides both services - client access and backhaul. Comparative performance analysis indicates this architecture provides the worst performance of all configurations, because backhaul and service compete for bandwidth. Also all single radio mesh architectures suffer from the send-receive-wait cycle shown in Figure 3. Since there is only radio, the mesh node has to listen, then send, then listen again. This intermittent stop-and-go behavior adversely affects network performance especially if the destination is far away and the traffic has to be re-transmitted ("hop") across many intermediate nodes first.

Dual-Radio with 1-Radio backhaul mesh

This configuration can also be referred to as a "1+1" network, since each node contains two radios, one to provide service to the clients, and one for backhaul. The "1+1" appellation indicates that these radios are separate - the radio providing service does not participate in the backhaul, and the radio participating in the backhaul does not service clients. These two radios can operate in different bands. For example, a 2.4 GHz IEEE 802.11

IEEE 802.11

IEEE 802.11 is a set of standards for implementing wireless local area network computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee . The base version of the standard IEEE 802.11-2007 has had subsequent...

b/g radio can be used for service and an 802.11a (5 GHz

GHZ

GHZ or GHz may refer to:# Gigahertz .# Greenberger-Horne-Zeilinger state — a quantum entanglement of three particles.# Galactic Habitable Zone — the region of a galaxy that is favorable to the formation of life....

) radio can be used for backhaul.

Most mesh products available today fall into this category. Separating service from backhaul improves performance when compared with single-radio ad hoc mesh networks. But since a single-radio mesh is still servicing the backhaul, packets traveling toward the Internet share bandwidth at each hop along the backhaul path with other interfering mesh backhaul nodes - all-operating on the same channel. This degrades throughput as shown in Figure 3, which are not as severe as for the single-radio mesh, but which are sizeable nevertheless. Second generation mesh products are best employed in 1 or 2 hop configurations.

2 radio backhauls

The last configuration shown (Figure 2) is one that provides separate backhaul and service functionality and dynamically manages channels of all of the radios so that all radios are on non-interfering channels. Performance analysis indicates that this provides better performance than the other two methods considered here. Note that the two backhaul radios for the 3-radio configuration shown in Figure 2 are of the same type - not to be confused with 1+1 so-called dual radio meshes where one radio is typically of type 802.11 a (backhaul) and the other of type 802.11 b/g (service). In the 3-radio configuration, 2 radios provide up link and down link backhaul functionality, and the other radio services the clients. Figure 4 shows how the two backhaul radios transmit traffic, with both radios operating independently and on separate channels.

Border security

The Naval Postgraduate School

Naval Postgraduate School

The Naval Postgraduate School is an accredited research university operated by the United States Navy. Located in Monterey, California, it grants master's degrees, Engineer's degrees and doctoral degrees...

in Monterey California, demonstrated a third configuration multi-radio wireless mesh network for border security. In a 2007 pilot system, aerial cameras kept aloft by balloons relayed real time high resolution video to ground personnel via a mesh network.

Laptop computers

A MIT Media Lab

MIT Media Lab

The MIT Media Lab is a laboratory of MIT School of Architecture and Planning. Devoted to research projects at the convergence of design, multimedia and technology, the Media Lab has been widely popularized since the 1990s by business and technology publications such as Wired and Red Herring for a...

project developed the XO-1 single-radio laptop or "OLPC" for under-privileged schools in developing nations and uses mesh networking (based on the IEEE 802.11s

IEEE 802.11s

IEEE 802.11s is an IEEE 802.11 amendment for mesh networking, defining how wireless devices can interconnect to create a WLAN mesh network, which may be used for static topologies and ad-hoc networks....

standard) to create a robust and inexpensive infrastructure. The instantaneous connections made by the laptops are claimed by the project to reduce the need for an external infrastructure such as the Internet to reach all areas, because a connected node could share the connection with nodes nearby. Greenpacket has implemented a similar concept with its application called SONbuddy.

VoIP

SMesh is an 802.11 multi-hop single-radio wireless mesh network developed by the Distributed System and Networks Lab at Johns Hopkins University

Johns Hopkins University

The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...

. A fast handoff scheme allows mobile clients to roam in the network without interruption in connectivity, a feature suitable for real-time applications, such as VoIP.

Software defined radio

Many mesh networks operate across multiple radio bands. For example Firetide

Firetide

Firetide is an American, international provider of wireless mesh network technology. Based in the Silicon Valley, Firetide designs and sells hardware and software for wireless networks. Firetide's products have been used in over 2000 installations in 40 countries.- Corporate history :Firetide was...

and Wave Relay second configuration dual radio mesh networks have the option to communicate node to node on 5.2 GHz or 5.8 GHz, but communicate node to client on 2.4 GHz (802.11). This is accomplished using Software Defined Radio (SDR).

External links

Limitations for providing redundancy on mesh or cable networks in a practical way in underground mines
NIST MANET and Sensor Network Security project
Miners Give a Nod to Nodes Article reprint from Mission Critical Magazine on Mesh in underground mining
The Mesh Debate Dailywireless Article on Structured mesh network scalability.
MIT Roofnet A research project at MIT that forms the basis of roofnet / Meraki
Meraki
Meraki is a cloud networking company that provides hardware and software for building large scale wired and wireless networks. These networks are used by businesses, schools, and other organizations that need wireless access points, multi-site wired networks, or both. It uses a centralized...

mesh networks
Wireless Mesh Networks Advantages and applications for Industrial and Mobile Solutions
Mesh Networks Research Group Projects and tutorials' compilation related to the Wireless Mesh Networks
The Commotion Wireless Project proposes building a 'device-as-infrastrucure' distribution crypted communications platform

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