.FLYINGHEAD WIRELESS INFRASTRUCTURE
.TITLE The history of mobile ad-hoc networks
.AUTHOR Humayun Bakht
.SUMMARY Wireless devices are getting smaller, cheaper, and more sophisticated. As these devices become more ubiquitous, organizations are looking for inexpensive ways to keep these devices connected. An ad-hoc network is a technology which could make that happen. This article by Contributing Editor Humayun Bakht explores the history and use of ad-hoc networks.
.DEPT
A mobile ad-hoc network is a collection of mobile nodes forming an ad-hoc network without the assistance of any centralized structures. These networks introduced a new art of network establishment and can be well suited for an environment where either the infrastructure is lost or where deploy an infrastructure is not very cost effective.
There are quite a number of uses for mobile ad-hoc networks. For example, the military can track an enemy tank as it moves through the geographic area covered by the network. Your local community can use an ad-hoc network to detect your car moving though an intersection, checking the speed and direction of the car. In an environmental network, you can find out the temperature, atmospheric pressure, amount of sunlight, and the relative humidity at a number of locations.
The whole life-cycle of ad-hoc networks could be categorized into the first, second, and the third generation ad-hoc networks systems. Present ad-hoc networks systems are considered the third generation.
The first generation goes back to 1972. At the time, they were called PRNET (Packet Radio Networks). In conjunction with ALOHA (Areal Locations of Hazardous Atmospheres) and CSMA (Carrier Sense Medium Access), approaches for medium access control and a kind of distance-vector routing PRNET were used on a trial basis to provide different networking capabilities in a combat environment.
The second generation of ad-hoc networks emerged in 1980s,when the ad-hoc network systems were further enhanced and implemented as a part of the SURAN (Survivable Adaptive Radio Networks) program. This provided a packet-switched network to the mobile battlefield in an environment without infrastructure. This program proved to be beneficial in improving the radios’ performance by making them smaller, cheaper, and resilient to electronic attacks.
In the 1990s, the concept of commercial ad-hoc networks arrived with notebook computers and other viable communications equipment. At the same time, the idea of a collection of mobile nodes was proposed at several research conferences.
The IEEE 802.11 subcommittee had adopted the term "ad-hoc networks" and the research community had started to look into the possibility of deploying ad-hoc networks in other areas of application.
Meanwhile, work was going on to advance the previously built ad-hoc networks. GloMo (Global Mobile Information Systems) and the NTDR (Near-term Digital Radio) are some of the results of these efforts. GloMo was designed to provide an office environment with Ethernet-type multimedia connectivity anywhere and anytime in handheld devices.
NTDR is the only "real" non-prototypical ad-hoc network that is in use today. It uses clustering and link-state routing, and is self-organized into a two-tier ad-hoc network. Development of different channel access approaches now in the CSMA/CA and TDMA molds, and several other routing and topology control mechanisms were some of the other inventions of that time.
Later on in mid-1990s, within the Internet Engineering Task Force (IETF), the Mobile Ad-Hoc Networking working group was formed to standardize routing protocols for ad-hoc networks. The development of routing within the working group and the larger community resulted in the invention of reactive and proactive routing protocols.
Soon after, the IEEE 802.11 subcommittee standardized a medium access protocol that was based on collision avoidance and tolerated hidden terminals, making it usable for building mobile ad-hoc networks prototypes out of notebooks and 802.11 PCMCIA cards. HYPERLAN and Bluetooth were some other ad-hoc network standards that addressed and benefited ad-hoc networking.
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The focus of current research is to standardize different existing schemes for different network controls in a single framework which could be taken as a standard for all the future applications utilizing ad-hoc networks as a networking technology. Wireless devices are getting smaller, cheaper, and more sophisticated. As these devices become more ubiquitous, organizations are looking for inexpensive ways to keep these devices connected. Building an ad-hoc network could make that happen.
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