An Introduction to Wireless NetworksIntroductionDemand for wireless networks has grown with the development of Mobile hardware, such as mobile phones, laptops and PDA's. With this demand has come industry standards and affordable, lightweight wireless networking hardware. This website will introduce you to the media of in wireless networking, give you an in depth look at Wireless Local area networks (LAN), familiarise you with the Industry standards and Issues.Wireless MediaWireless connections all use some form of Radio Frequency (RF) technology, using air as the transmission medium instead of a wire to transmit and receive data.There are 5 categories generally used for networks.Radi ...view middle of the document...
Microwave- (2- 40 GHz) has minimal effects on humans and can transmit through thin walls. Its bandwidth can be split into a number of sub-channels for speed. Used for telecommunications, television transmission, and also for short point to point links between buildings. The microwave is difficult to deploy and requires a licence.Spread spectrum radio - this uses wireless networking communications technology first developed by the military for secure and noise-immune communications. Only recently become viable for commercial use, with smaller, faster and cheaper products. Spread spectrum is easy to implement and does not require a license. It operates at a lower bandwidth than microwave, and as distance from the initial signal increases, a lower bandwidth can be used. Data is sent in small pieces over a number of frequencies available for use at any time in the specified range.This can be done in 1 of 2 ways:Frequency-hopping spread spectrum (FHSS) - sends a short burst of data, changes frequencies and then sends another short burst to increase the probability of successful data transmission. A number of independent FHSS networks can exist in the same physical area without interfering with each other because the FHSS devices agree on which frequencies to hop to, and use each frequency for less than 400 milliseconds before hopping. FHSS only uses 1 MHz or less of the available bandwidth. This is the method that has been adopted by Shared Wireless Access Protocol (SWAP) networks.Direct-sequence spread spectrum (DSSS)- communicate by each byte of data is split into several parts and sent simultaneously on different frequencies to ensure the document is received. This uses a lot of the available bandwidth, about 22 MHz. DSSS products capable of data rates of 6 Mbps, (4-6 times faster than currently available FHSS products), and approaching that of 10 Base-T wired hubs. FHSS devices are less prone to interference than DSSS devices because they use any given frequency for such a short time. But DSSS is capable of much greater speed than FHSS since these devices can send a lot more data at the same time. Currently, FHSS-based devices are easier and cheaper to produce.What is Wireless LANA wireless LAN (WLAN) is a network without wires. WLAN's use radio frequencies as their transmission media, sending network traffic sailing over the air. It is a flexible data network system applied as an extension to, or as an alternative for a wired LAN. The WLAN market is a high-growth area with businesses eagerly wanting all the benefits that wireless can offer.'The term wireless networking refers to technology that enables two or more computers to communicate using standard network protocols, but without network cabling. The current buzzword however generally refers to wireless LANs.' VicomsoftTopologyOptions for wireless network topologies:Ad-hoc (peer-to-peer) - This is a basic system where the WLAN has a number of computers each with a wireless network...
