HomeRF (Home Radio Frequency)
aka SWAP (Shared Wireless Access Protocol)
a type of WLAN (Wireless Local Area Network)
Wireless networks allow:
* Computers to talk to each other – sharing files and drives,
* Multiple computers to share a peripherals – most importantly the printer,
* Multiple computers to share a single internet access, and
* Laptops to be used from any place throughout the home.
All this with no wires!!!! HomeRF creates a network by using radio frequency (RF) signals to connect computers instead of wires, sending RF signals between computers to share information. It makes it easier to set up and change (move things around) the wireless network than traditional wired networks.
In some instances computers can talk directly to each other (know as peer to peer or point to point). In other situations a main computer, known as the server or access point can talk to all the computers and peripherals in a "hub and spoke" configuration.
The Institute of Electrical and Electronics Engineers (IEEE) sets the standards for wireless-Ethernet specification, known as IEEE 802.11. It designated two ways of communicating between devices and allowed for speeds up to 2 Mbps. The two communications methods are direct-sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS). Both methods use frequency-shift keying (FSK) technology to encode data. (Definitions of DSSS, FHSS, and FSK can be found at the bottom this page). Both methods are based on spread-spectrum radio waves in the 2.4-gigahertz (GHz) range. The significance of being in the 2.4GHz range is that this is a RF band set aside (by the FCC) for low power use and does not required a FCC license.
HomeRF is FHSS-based mainly because FHSS-based devices are easier and cheaper to produce. The RF signals can penetrate through walls and ceilings to provide a maximum network range of up to 150 feet. Home RF supports both data networking as well as six channels of voice, with bandwidth constantly allocated between the two as needed.
"HomeRF is an alliance of businesses that have developed a standard called Shared Wireless Access Protocol (SWAP). A sort of hybrid standard, SWAP includes six voice channels based on the Digital Enhanced Cordless Telecommunications (DECT) standard and the 802.11 wireless-Ethernet specification for data. SWAP devices make 50 hops per second and transmit information at 1 Mbps. Depending on the manufacturer, some of these can step up to 2 Mbps if there is very little interference in their operational area." Source:howstuffworks.
The advantages of SWAP:
* It's inexpensive ($70 to $200 per computer).
* It's easy to install.
* It requires no additional network wires.
* It usually has no access point.
* It uses six full-duplex voice channels and one data channel.
* It allows up to 127 devices per network.
* It allows multiple networks in the same location.
* You can use encryption to make your data secure.
The disadvantages of SWAP:
* It's not very fast (normally 1 Mbps).
* It has a limited range (75 to 150 ft).
* It's difficult to integrate into existing wired networks.
How do we enable a computer to participate on HomeRF network? Install or insert a ISA, PCI or PCMCIA card into the computer which contains a wireless transceiver and a small, integrated antenna. One could also use an external USB adapter that is inserted into both the computer and the PCMCIA card. Currently, because of the need to use dedicated cards, only computers can participate in a SWAP network. Printers and other peripheral devices need to be physically connected to an individual computer and the entire network can share the printer.
Because it needs no access point, HomeRF networks are significantly cheaper than the other currently viable wireless network, WECA's Wi-Fi. The tradeoffs for lower cost are lower speed and shorter distance. If you can set up a wired network using HomePNA or traditional Ethernet, you will get 10 to 100 times the speed of a HomeRF network for the same amount of money or less. This speed may be convenient but unless you plan to send large amounts of data (like video) back and forth over the network, SWAP speed is probably adequate for most home use.
The Wireless Ethernet Compatibility Alliance (WECA) has headed in a completely different direction than HomeRF. It is more targeted at office use than home networks and uses DSSS instead of FHSS because of the higher data rate DSSC can attain. These devices (which follow the 802.11b standard) are also known as Wi-Fi (for "wireless fidelity", like Hi-Fi for "high fidelity" in audio equipment
The advantages of Wi-Fi:
* It's fast (upto11 Mbps for 802.11b, 54Mbps for 802.11a).
* It's reliable.
* It has a long range (up to 1,000 ft in open areas, up to 250 ft in closed
* It's easily integrated into existing wired-Ethernet networks.
* It's backwards compatible with original 802.11 DSSS devices.
* Products are sold al a carte allowing for customized configurations.
The disadvantages of Wi-Fi:
* It's expensive (access point from $300 to $1400, cards from $99 to
* It requires an access point.
* It can be difficult to set up.
* Speed can fluctuate significantly.
Main Source http://www.howstuffworks.com/wireless-network.htm
By the end of 2000, according to International Data Corp. (IDC), about half of all U.S. households had a computer and more than 20 million of those had more than one computer. Wouldn’t it be nice to have them talk to each other?
HomeRF Working Group, which is working to establish an open industry specification for unlicensed RF digital communications for home PCs and consumer devices has a web sitehttp://www.homerf.org especially informative on their site is the learning center:
Another information source on the current happenings in the RF and wireless design Industry is RFGlobalnet:http://www.rfglobalnet.com/content/homepage/default.asp?VNETCOOKIE=NO
The main commercial supplier I saw in my HomeRF research was Proxim:www.proxim.com.
Study that states that HomeRF is more secure than 802.11b WLAN:http://homerf.org/data/tech/security_comparison.pdf
Intel’s web page had a good video on what WLANs are and what they could do. From the page listed below choose link titled "Wireless Lan Technology & Solutions Demo" found in the take action box to the right of the screen.
Another interesting article on HomeRF:
Asks whether Intel abandoning HomeRF will hurt HomeRF’s success?http://www.internetnews.com/bus-news/article.php/3_720021
Some sites for comparison shopping and advice on purchasing HomeRF:
DSSS sends pieces of data simultaneously over a number of the discrete frequencies available for use at any time in the specified range. These devices communicate by splitting each byte of data into several parts and sending them concurrently on different frequencies. DSSS uses a lot of the available bandwidth. DSSS is capable of much greater speed than FHSS since these devices can send a lot more data at the same time.
FHSS sends a short burst of data, shifts frequencies (hop) and then send another short burst. Since the FHSS devices that are communicating agree on which frequencies to hop to and use each frequency for a brief period of time (less than 400 milliseconds) before moving on, several independent FHSS networks can exist in the same physical area without interfering with each other. Because FHSS devices generally send data on just two to four frequencies simultaneously, they only use 1 MHz or less of the available bandwidth. Because they use any given frequency for such a short time, FHSS devices are less prone to interference than DSSS devices
FSK uses two frequencies, one for "1"s and the other for "0"s, to send digital information between the computers on the network.