Archive for May 3rd, 2014

May 3, 2014

Wireless Mesh

mesh potato

firechat

A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology; each node is connected to one or more other nodes, and information is passed from one node to the next, until it reaches its target destination. As in most cases, there is more than one path from one node to another, making such networks very reliable. When a node fails, the data will simply take another route. This type of infrastructure can be decentralized (with no central server) or centrally managed (with a central server).

The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. Mesh architecture sustains signal strength by breaking long distances into a series of shorter hops. Intermediate nodes not only boost the signal, but cooperatively make forwarding decisions based on their knowledge of the network, i.e. perform routing. Such an architecture may with careful design provide high bandwidth, spectral efficiency, and economic advantage over the coverage area.

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May 3, 2014

Cognitive Radio

frequency allocation

Cognitive Radio

A cognitive radio is a transceiver that dynamically switches between optimal wireless channels in its vicinity. It automatically detects available channels, then accordingly changes its transmission or reception parameters to allow more concurrent wireless communications in a given spectrum band at one location. This process is a form of dynamic spectrum management.

The cognitive engine is capable of configuring waveform, protocol, operating frequency, and networking parameters. Units can exchange information about the environment with the networks it accesses and other cognitive radios (CRs). A CR ‘monitors its own performance continuously,’ in addition to ‘reading the radio’s outputs’; it then uses this information to ‘determine the RF environment, channel conditions, link performance, etc.’, and adjusts the ‘radio’s settings to deliver the required quality of service subject to an appropriate combination of user requirements, operational limitations, and regulatory constraints.’

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