Maintaining stability of a wireless network by adjusting transmitting period

#Ad-hoc wireless networks are networks that are formed and de-formed on-the-fly without the need for system administration. Ad-hoc networks can be mobile, standalone, or networked with other networks such as wide area networks or the Internet. Ad-hoc wireless devices communicating in a wireless area network are able to detect the presence of other ad-hoc devices, establish communication links with the other devices, and communicate information such as packetized digital data. An ad-hoc network is essentially infrastructureless since there is no need for fixed radio base station, wires, or routers in the network. In communicating with each other, ad-hoc devices may employ many different packet routing methods to route wireless digital packets between mobile hosts in an ad-hoc mobile network.

#One wireless networking protocol of significant importance due in part to its growing use in devices such as palmtop computers, personal digital assistants (PDAs), laptop computers, and Internet mobile phones is IEEE 802.11. The 802.11 standard specifies two modes of operation: an infrastructure mode where an access point provides the link between wireless stations and wireline legacy infrastructure, and an ad-hoc mode where there is no access point, and wherein all stations contribute to the distributed management and control of the network.

#802.11 equipped devices configured to run in infrastructure mode are especially well suited for office, home, or café environments where there is an access point, and where the concentration of mobile devices is relatively low and the mobile devices are slow moving or stationary. For example, in a café or office setting a mobile device such as a laptop computer may enter a wireless network and remain stationary for a long period of time while the user of the device accesses other devices or other networks, such as the Internet. Location and context based mobile services are another infrastructure mode application. For example, a user in a shopping mall could obtain the lowest price for a product they are interested in. Or, a user at an art museum could automatically receive on their PDA more detailed information on a work of art as they approach to view the work of art.

#FIG. 1 is an enhanced transportation network.

#FIG. 2 is a mobile communication device.

#FIG. 3 is a transportation application of the mobile communication device.

#FIG. 1 shows an enhanced transportation network 10. The transportation network comprises a plurality of mobile communication device equipped vehicles 100 and optionally a plurality of vehicles not equipped with communication devices 110. In FIG. 1 vehicles 100 and 110 are automobiles and are traversing a network of roadways in the transportation network 10. The roadways may be city streets, rural streets, interstate highways, or any other network of roads for which automobiles are adapted for travel. The automobiles may be any other type of vehicle capable of traveling on roadways. It is understood when using the term “equipped vehicle” that reference is being specifically made to the mobile communication device traveling with the vehicle, and not to the vehicle, type of vehicle, or mode of transportation employed by the vehicle. As such, a vehicle may include not only automobiles, but motorcycles, bicycles, human beings, animals, aircraft, water vehicles, and any other system capable of transporting people and goods.

#The equipped vehicles 100 have access to a wireless communication network 120. The communication network 120 allows direct vehicle-to-vehicle communication. As used herein, direct vehicle-to-vehicle communication, or direct communication, is intended broadly to encompass communication between at least two vehicles or communication devices whereby communications sent from one vehicle or communication device are received directly by another vehicle or communication device without the use of repeaters, base stations, up-converters, down-converters, intermediary amplifiers, auxiliary antennas, auxiliary communication systems, and the like. Preferably the network is a wireless network such as an IEEE 802.11 or Wi-Fi (Wireless Fidelity) communication network operating in ad-hoc mode, but may be other types of wireless networks capable of direct vehicle-to-vehicle communications, and capable of transmitting and receiving digital data. The non-equipped vehicles 110 do not have access to the communication network 120 and thus cannot communicate with any of the equipped vehicles 100.

#Each of the equipped vehicles 100 in the transportation network 10 is outfitted with a mobile communication device 101. FIG. 2 shows in greater detail a mobile communication device 20 local to the equipped vehicles 100. It is not important how the mobile communication device 20 is installed in each vehicle, only that it travels with the vehicle. For example, the mobile communication device 20 may be installed during the manufacture of the vehicle, or it may be a subsystem component of another system within the vehicle, or it may be any combination of vehicle subsystems and external devices. Alternatively, the mobile communication device 20 may be a self contained external unit that is placed in the vehicle after the vehicle manufacture, such as is common with current GPS mapping systems such as those made by Garmin. Still another possibility is that the mobile communication device 20 is a portable handheld unit that is not permanently affixed to a point in or around the vehicle but is rather temporarily brought into the vehicle when needed. Or, the mobile communication device may comprise two or more sub-system devices in communication with each other via an interface such as serial, parallel, optical, wireless, and the like.