System and method for communication in a wireless mobile ad-hoc network

Abstract

A system and method for improving digital communication in a wireless mobile ad-hoc network. More specifically, the system includes one or more portable network devices operable to support the seamless operation of a self-initializing, self-healing, adaptive portable network. The portable network devices implement protocols that provide bandwidth management capabilities for use with radios, routers and other wireless network devices. Each portable network device includes at least one wireless transceiver, a processor and control software. The processor and control software are logically coupled to the wireless transceiver to facilitate digital communication via a plurality of communication channels with other network devices.

Description

[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 681,464 filed May 17, 2005, which is incorporated by reference herein in its entirety.FIELD OF THE INVENTION[0002]The present invention is directed generally to improvements in wireless communication networks. More specifically, the present invention is directed to devices and protocols that are useful, for example, in a wireless mobile ad-hoc network having dynamic topology.BACKGROUND OF THE INVENTION[0003]A wireless communication network typically includes a wireless client device or station (STA) that communicates with one or more access points (APs) that are connected to a communications infrastructure. The communications infrastructure typically consists of routing nodes which facilitate the movement of message packets through wired or wireless network connections. In a typical wireless infrastructure system, a STA may roam within the network by association and disassociating with multi...

AI Technical Summary

Benefits of technology

[0013]In some embodiments, it is an object of the present invention to develop a MANET Node Device, network routing protocols and administrative systems that support rapid and robust adaptation to the factors impacting the efficient propagation of message packets through a mobile wireless network. There is also a need for a MANET Node Device that readily supports the interconnection between the MANET network and other networks. There is also a need for a MANET Node Device that minimizes the need for skilled installation and administration of the network by implementing protocols, techniques, mechanisms, and processes to self-initialize and auto-configure the network for optimized network reliability and availability, channel analysis and selection, security and other network services. There is also a need for a MANET Node Device that can select and use multiple radio transceiver channels while minimizing the impact of interference on message packet throughput. There is a further need to integrate these protocols, techniques, mechanisms, and processes in a way that the MANET Node Devices are portable and usable in harsh physical environments and situations.

[0015]The preferred embodiment of the present invention includes a MANET Node Device having a power-efficient computing platform, enabling it to function under portable battery power. The MANET Node Device is also equipped with at least one radio transceiver providing Physical layer (Layer 1) and Data Link layer (Layer 2) services for establishing a Mobile Infrastructure Peer (MIP) communications link with neighboring MANET Node Devices. For example, a radio transceiver which supports IEEE approved or proposed standards 802.11a, 802.11b, 802.11g, 802.11n, 802.16a, 802.16e or 802.20. The MANET Node Device can also provide AP services to STAs on at least one radio transceiver. The computing platform, radios and related electronics are encased in housing which reduces the egress and ingress of radio frequency interference (RFI) and mitigates the buildup of internal heat.

[0016]The present invention includes a message packet routing protocol implemented at OSI Layer 2. The protocol uses a hybrid path discovery technique comprised of both proactive and reactive path discovery methods and thus enables fast failover to alternate pathways while adding minimal protocol overhead. For example, the proactive path discovery techniques of the message routing protocol include causing an introductory message to be generated by a MANET Node Device when a STA associates with an AP, as well as the reading, analysis and storage of reverse route information. Reactive path discovery techniques include a discovery request message that is sent by a MANET Node Device when a local table entry exists for the message destination. The MANET routing protocol also includes path cost calculations which encourage a preference for higher bandwidth connections, while emphasizing communications reliability. The MANET routing protocol also includes Layer 2 flood control mechanisms for mitigating flood attacks and reducing the bandwidth impact of certain legitimate flood messages such as the MANET routing protocol discovery request messages and address resolution protocol (arp) requests used by Internet Protocol version 4 (IPv4).

[0028]A bi-directional frequency translator (transverter) downconverts and upconverts MANET Node Device radio transceiver signals to RF bands other than those provided by the radio transceiver. The transverter interacts with the signal from the transceiver to either convert the transceiver transmit signal up to a higher frequency and convert the receive frequency down to the transceiver receive frequency, or convert the transceiver transmit signal down to a lower frequency and convert the receive frequency up to the transceiver receive frequency. The transverter, coupled with a low-noise amplifier appropriate for the frequencies being converted up or down to, provides a means to operate the MANET Node Device in frequencies with certain desirable characteristics, such as better propagation through obstacles.

[0030]A single board computer design based on a low-power processor allows the MANET Node Device to run on batteries. Antenna type and its physical location on or in the MANET Node Device are selected to improve throughput by reducing co-channel interference. The amplifiers increase the functional distance between MANET Node Devices by increasing transmit and receive signal gain. The amplifiers incorporate fast acting pads to overcome susceptibility for overdriving the receiver. An integrated signal filter system improves the problem of co-channel interference and a composite canceller is used to further reduce the interference. A tricolor LED and control software provides user feedback on the status of the node device and its connection to the mesh. A down converter or up converter package enables the radios to operate in lower or higher frequencies with better propagation or lower interference characteristics.

Problems solved by technology

However, typically APs and the associated network topology remain stationary and static.

However, the repeater device 101 will effectively halve the potential bandwidth if it is sending and receiving on the same channel.

Therefore, uninterrupted data streams passing both in and out of a repeater can only use, at most, half the available bandwidth on the channel.

Wireless links have significantly lower capacity than wired links because they are affected by additional error sources that result in degradation of the received signal and high bit error rates.

Mobile nodes are more autonomous and less capable of centralized administration.

The mobile nodes in a network must share common radio frequencies and are therefore prone to greater interference from each neighboring node.

Dynamic connections and the arbitrary manner in which nodes are connected in a MANET create a challenge to the routing method.

However, STP and its variants, such as Rapid Spanning Tree Protocol and Multiple Spanning Trees Protocol, do not perform well in networks where the quality or availability of connections between routing nodes is dynamic and subject to frequent change.

Because of this, STP and other protocols which rely upon root node techniques do not perform well in dynamic network environments and can cause network reliability issues due to unacceptable periods of interrupted communications while the network routing is rediscovered and disseminated to all routing nodes.

However, the AODV protocol assumes that each link is symmetric and is not well adapted to networks having asymmetric pathways between routing nodes.

DSR is based on a source routing method and while supporting asymmetric pathways between routing nodes, it imposes the overhead of communicating the entire route map with every message packet.

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