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Wi-Fi Mesh Networks, The path to mobile Ad Hoc

ABOUT THE AUTHOR

Bio: Jonathan Walker, P.E. is a staff member of the Wi-Fi Technology Forum and founder of Applied Wireless Local Area Network, Inc (http://www.AppliedWLAN.com). The company specializes in services surrounding Wireless and Wired LAN roaming: Free/Fee based Wi-Fi HotSpots, WLAN equipment reseller and WLAN marketing/training. Mr. Walker is a licensed professional engineer, an IEEE member, author and has a B.S. along with a M.S. in Engineering. The author may be reached at jwalker@wi-fiforum.com.


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Wi-Fi Technology Forum© 2004-2005, permission to use this paper outside the scope of this site should be gained beforehand. However, permission for a paragraph and a link to this material is hereby granted.

1- Introduction to Wi-Fi Mesh Networks


In its simplest form, a wireless mesh network is a collection of wireless devices maintaining RF connectivity to create a seamless path for data packets to travel. In many ways, a wireless mesh network resembles an idealized version of a top-level Internet backbone in which physical location is less important than capacity and network topology (Figure 1). At least one wireless device (or node) is connected to a wired Internet backbone and each data packet is bound for the same destination but not necessary using the same sequential path of nodes.

The Internet router determines a path between the user and the physical backbone. In the wireless mesh environment, a network can be envisioned as a collection of access points, routers, or end users (equipped with wireless receiver/transmitters) that are free to move arbitrarily but maintain a reliable communication that sends and receive messages.





Figure 1

Each data packet traveling on the Internet backbone has a different sequential path of nodes even though the source and destination are the same.


The fundamental structure of a Wireless Local Area Network (WLAN) is the peer-to-peer or peer-to-multipoint communication between two wireless devices. The purpose is forming a collection of wireless devices that maintain connectivity with each other while transferring or routing data in a random manner. In peer-to-peer (P-to-P) configuration, each wireless link replaces a single communication cable and can converse reliably as long as the two end points are close enough to escape the effects of Radio Frequency (RF) interference or signal loss (Figure 2a).

A peer-to-multipoint (P-to-Mp) system has one centralized administrator (or hub) that associates with multiple nodes instead of peer-to-peer collaboration (Figure 2b). In general, a reliable connection is dependent upon the distance between the wireless devices; thus, forming a wireless circle (or cell) that one must stay within to maintain communication with others. No different than saying, “can you here me now?” as one roams about a home with a PDA, laptop, or tabletop. Although multipoint based wireless networks are often inexpensive and not complicated to install, they quickly exceed their maximum output potential when line-of-sight obstacles stand in the way or the number of nodes transcends the RF transmitter’s relatively limit data throughput.







Figure 2a | Figure 2b

WLAN Peer-to-Peer connection | WLAN Peer-to-Multipoint

(i.e., wireless laptop to wireless laptop) | (i.e., access point (Hub) to multiple wireless devices)

Added:  Thursday, November 10, 2005
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Related Link:  Applied Wireless Local Area Network, Inc
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Language: eng
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