Title: Wireless Protocols
This document is a high level view of few prevalent wireless technologies.
The aim is to create a perspective about technology that we popularly refer to as wireless – in these cases devices communicate in isolation or as part of a larger, more complex network.
The following information is provided in the comparison table below:
A small comment on the technology.
There are a large number of protocols. This can be very confusing to the beginner. The protocols mentioned here are popular and indicative ones for that technology – not an exhaustive list. This value is provided here only for information, just to help make the association, and as a pointer to further details to help understand what they do with respect to addressing, handshaking, data transmission, encoding; point to point or broadcast; node/ instrument profile as transmitter, receiver, repeater, master, slave, etc.
Very often the protocols that these technologies are referred to by are the low level protocols (Layers 1 & 2 as per OSI model).
- The 802.* series.
- Phone manufacturers that support WiFi will say that they support IEEE 802.11 a/b/g/n
Is provided for information purposes only. The frequency range gives an idea about the transmission characteristics.
The characteristics vary widely across different spectrum bands. There is no definite trend, and each one is different.
For example, low frequencies ( long wave)may travel longer distances since they are reflected by the earth and the atmosphere.
Frequencies in the optical range have their own unique properties. Very high frequencies have good penetration, and can pass through barriers like walls, for example.
Other generalizations, not wholly accurate, are that at higher frequencies more data can be transferred, as compared to lower frequencies. Also higher frequencies consume more energy (in part due to the absorption characteristics of the media)
A popular classification is of the kind to ULF, VLF, VHF, EHF, etc.
In case of wireless communication, the range that can be covered depends upon the power available. Frequency bands to transmit information are an important and precious resource, and this controlled by a regulatory body.
All the technologies that we look at here operate locally (except mobile technologies) over small distances, and come under the ISM (Industrial, Scientific and Medical) band. ISM operates at 868 MHz in Europe, 915 MHz in the USA and Australia and 2.4 GHz in most jurisdictions worldwide. Data transmission rates vary from 20 kilobits/second in the 868 MHz frequency band to 250 kilobits/second in the 2.4 GHz frequency band.This band allows people/devices to communicate locally wirelessly. The regulation controls the range over which the devices can transmit.It does so by limiting/specifying the power rating.
The value here gives an idea of usual ranges in domestic applications. Like between point to point communication. Or between a transmitter and a receiver. As opposed to between nodes in a network. Continue reading