Band manager for use in multiple-channel networks

Details Band manager for use in multiple-channel networks Band manager for use in multiple-channel networks

1999-10-12

2003-09-16

Cangialosi, Salvatore (Department: 2661)

Multiplex communications

Data flow congestion prevention or control

Flow control of data transmission through a network

C370S329000, C370S437000

Reexamination Certificate

active

06621795

ABSTRACT:

TECHNICAL FIELD
The present invention is directed to a method and apparatus for use in a multiple-channel or frequency agile network, and more particularly to a method and apparatus that selects a channel for transmitting and/or receiving packets in a multiple channel network.
BACKGROUND ART
Ad hoc wireless networks are commonly used in military, emergency, and temporary (e.g., business meetings, campaign headquarters) networks because they do not rely on base stations or any other fixed infrastructure, making them particularly suitable for situations where communications need to be established quickly. As is known in the art, each node in an ad hoc network is normally responsible for routing the packets of other nodes in the network. As a result, nodes in an ad hoc network must employ complex routing protocols to direct packets efficiently through the network.
Different radio frequencies have different propagation characteristics. It is therefore advantageous for radio frequency devices to be frequency agile to overcome restrictive radio environments, increase available bandwidth, and/or reduce congestion on a preselected radio channel. This can be accomplished via a multiple-channel network; however, to take full advantage of the multiple channels offered by a multiple channel network, ad hoc networking protocols must be significantly more complex than protocols for a single channel network. Placing the channel decision-making capability into networking software is an option, but doing so tends to increase the complexity of the networking software dramatically. Ideally, each node should know the complete state of all links in the ad hoc network and should also be able to manage all the different types of traffic that go through each node. Such a large amount of information is further complicated if the network is designed to retransmit packets over a second channel if the first channel fails. As a result, the complexity of the network layer multiplies for each channel added to the network.
The complexity problem becomes particularly difficult when handling control messages between nodes that are trying to establish a link in the ad hoc network. Often, this function is performed by a clustering module, which broadcasts beacons, known as neighbor discovery broadcasts (NDBs), from each node on a selected channel to notify other nodes of its existence. If a node A hears beacons from node B, the two nodes attempt to establish a link via a four-way handshake. Preferably, all of the packets in the four way handshake traverse the same channel. Additionally, it is important for the NDBs to be heard on any channel, yet it is undesirable to add multiple channels, and therefore added complexity, into the clustering module to transmit multiple beacons over multiple frequencies and to determine the channel at which each beacon was transmitted.
There is a need for a method and apparatus that simplifies the networking layer for a multiple-channel network system and minimizes the number of routing and transmission decisions being made by the network.
SUMMARY OF THE INVENTION
Accordingly, the invention is directed to a band manager that is placed in a multiple channel network system. The band manager is implemented via software and simplifies the networking layer for a multiple channel network system by shielding the networking protocols from having to decide which channel to use for transmission. More particularly, the band manager filters all transmissions between the networking layer and the radio layer and decides which channel to use at any given time, thereby removing the channel decision-making function and its associated complexities from the networking layer. As a result, only the band manager, and no other component in either the networking layer or the radio layer, decides which channel to use. Further, because the band manager is the only component in the network that makes channel decisions, the other components in the network act as if the radio is a single-channel radio and as if the network is a single-channel network; the radio simply sends the packet on the one channel specified by the band manager.


REFERENCES:
patent: 4627045 (1986-12-01), Olson et al.
patent: 5414697 (1995-05-01), Osaki
patent: 5850592 (1998-12-01), Ramanathan
patent: 6219547 (2001-04-01), Qaddoura et al.
patent: 6353742 (2002-03-01), Bach
patent: 6404777 (2002-06-01), Hattori et al.

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