Common Wireless Network Terminology
Radio
Radio is a technique that enables the communication of signals representing information over the electromagnetic spectrum. In general the process used is as follows.
- A carrier wave is created, via an oscillator, at a given frequency and with a given bandwidth
- Modulation of this wave with the information to be communicated is performed
- Additional coding of the signal in an effort in an attempt to compensate for the uncertain nature of radio communications and technical artifacts associated with electromagnetic waves is done
- The signal is amplified
- The signal is applied to a transmit antenna, and the signal enters the radio channel
Amplifier
Amplifiers are electronic circuits that boost the power (increase the amplitude) of a signal fed to them. While many different types of amplifiers are broadly applied across many electronic applications, two important amplifiers used in wireless include the power amplifier (PA), which is used to boost the signal sent to a transmit antenna, and the low-noise amplifier (LNA), used to boost the typically very weak signal appearing at a receiving antenna.
*RapidConnect devices are power amplified.
Antenna
An Antenna acts as the interface between the radio waves on the electromagnetic spectrum and the rest of the system.Antennas cover a broad range of designs and applications, from simple "whip" antennas to so-called "smart" antennas with active (powered) electronic components.In general, antenna designs are optimized for a specific range of frequencies, with lower frequencies usually requiring physically larger antennas, and are either "omnidirectional", transmitting towards and receiving from all directions simultaneously, or "directional", optimizing both transmission and reception across a limited number of degrees of arc.
*RapidConnect modules come with SMD Chip Antenna or U.FL RF connector options
Band
A range of frequencies utilized for a given transmission. A band is often subdivided by a given frequency range into channels that are statically or dynamically assigned and individually utilized for a given service or application.
Bandwidth
The range and thus amount of spectrum utilized in a given transmission, with the nominal frequency being the centre of this range.
Capacity
The term capacity is often used to describe the ability of a shared channel to carry the maximum information at any given moment in time, as opposed to maximum throughput for any given transmitter. Capacity refers to an upper bound on the ability of any given channel to support simultaneous, distinct, and diverse communications and is usually more important than throughput in the specification, design and operation of most implementations.
Congestion
Congestion is a phenomenon that occurs when the capacity of a channel is oversubscribed. This leads to the need for queuing that delays access to the channel, at least for some traffic. Techniques designed to address congestion include prioritization schemes such as quality of service (QoS) and class of service (CoS); data compression; and the addition of more capacity via the utilization of additional bands or channels.
Interference
Interference is a general term for signals that conflict with a given signal that is intentionally being transmitted. The net effect of interference is a given signal in effect becomes weaker, even to the point where the intended receiver can no longer detect the signal.
Line of Sight (LoS)
Line of sight refers to a clear, unobstructed physical path between a given transmitter and receiver. For many applications, LoS is essential, especially at very high frequencies which only propagate linearly and not very well (if at all) through obstructions. When LoS is not feasible, it may be possible to use additional radios to relay around the obstruction, with the use of mesh techniques. Mesh Network topologies are the backbone of Zigbee networks as well as other IoT standards.
Wireless Network Topology
Topology refers to the logical and/or geometric orientation of a given network implementation. In wireless, three key topologies come into play
- "P2P"(point-to-point) means that every node in a given network must be able to communicate directly with every other node. The logistics here can become quite complex, so P2P is limited to single connections between two nodes or for connections among a small number of nodes within close physical proximity to one another.
- A "Star" (point-to-multipoint) configuration where all traffic between nodes in the network (and beyond, via bridging) must go through a single central point. For instance, Cellular networks are P2MP with handoff of client traffic to other cells via backhaul facilities.
- "Mesh" configuration enables the construction of arbitrarily large and complex configurations by enabling traffic to flow through intermediate nodes, which act like switches forwarding traffic not intended for the relaying node itself. Many possible implementations and configurations are possible here, and both infrastructure and client nodes can, in theory, serve as relay points.
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Next Section
You can now move on to Zigbee Basics.
References:
http://www.networkworld.com
www.Zigbee.org
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