12 March 2006
Connections
There are lots of different ways that electronic devices can connect to one another: component cables, electrical wires, Ethernet (network) cables, WiFi (wireless networking), infrared signals, and Bluetooth. The first two have been around for a while, so we’ll bypass a discussion on how wires work and move into ethernet and the others.
Ethernet
Networking has been around for a long time and most of
us have used it, even if we haven’t realized it at the time. There are
two basic types
of networks – local-area network (LAN) and wide-area
network (WAN).
LAN technologies connect many devices that are relatively close to each other, usually in the same building. The library terminals that display book information would connect over a local area network. WAN technologies connect a smaller number of devices that can be many kilometers apart. For example, if two libraries at the opposite ends of a city wanted to share their book catalog information, they would most likely make use of a wide area network technology, which could be a dedicated line leased from the local telephone company, intended solely to carry their data.
The Internet is a rather large WAN. You connect to that WAN through a dial-up modem, a DSL modem, or a cable modem. If you have more than one computer in your home or at work that connect to each other and or simultaneously connect to a DSL or cable modem, you have a LAN.
Most networks use Cat5 (category 5) cables to connect to each other and network devices, such as printers. Cat 5 is a name defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA). Cat5 is the 5th generation of twisted pair Ethernet cabling and the most popular of all twisted pair cables in use today. The telephone cabling inside the walls of your house is most likely Cat3.
Computers on a LAN connect to each other through a network switch. The switch controls how information is communicated to each of the devices on the network. If the computers share a single Interconnection, it is usually done through a router. The function of a router is to take that single connection and separate the signals to and from the individual computers.
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WiFi
WiFi (wireless fidelity, taken from Hi-Fi) is the wireless
way to handle networking. It is also known as 802.11 networking and wireless
networking.
The big
advantage
of WiFi is its
simplicity. You can connect computers anywhere in your home or office
without the need for wires. The computers connect to the network using
radio signals, and computers can be up to 30 metres (100 feet) or so
apart. However, the radio signals are not very powerful and are affected
by walls
and
other wireless devices, such as mobile phones and cordless phones.
WiFi radios that work with the 802.11b and 802.11g standards transmit
at 2.4 GHz, while those that comply with the 802.11a standard transmit
at 5 GHz.
You can use a wireless router to connect your laptop to the Internet without having to plug it into the router. The range of the wireless connection is affected by distance and walls, so you may have to change seats to find a good spot to connect.
Hotspot
A hotspot is a connection point for a WiFi network. It is a small box
that is hardwired into the Internet. The box contains an 802.11 radio
that can simultaneously talk to up to 100 or so WiFi devices. There
are many WiFi hotspots now available in public places such as restaurants,
hotels, libraries, and airports.
WiFi hotspots can be open or secure. If a hotspot is open, then anyone with a WiFi card can access the hotspot. If it is secure, then the user needs to know a WEP key to connect.
WEP (Wired Equivalent Privacy) is an encryption system for the data that is sent through the air. WEP has two variations: 64-bit (really 40-bit) and 128-bit encryption (really 104-bit). 128-bit encryption is more secure and is what most people use if they enable WEP. For a casual user, any hotspot that is using WEP is inaccessible unless you know the WEP key.
The hotspots at Heathrow Airport and Luton Airport (in London, England), and Dublin Aiport and Shannon Airport (in Ireland) are open and anyone can access the Internet for free. The hotspots at most U.S. airports - e.g., San Francisco, Los Angeles, and Chicago - are secure and require a fee payment before accessing the Internet.
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Bluetooth
Bluetooth takes small-area networking to the next level by removing the
need for user intervention and keeping transmission power extremely
low to save battery power.
Bluetooth is essentially a networking standard that works at two levels:
- It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.
- It provides agreement at the protocol level, where products have to agree on when bits of information are sent, how many will be sent at a time, and how the parties in a conversation can be sure that the message received is the same as the message sent.
The big draws of Bluetooth are that it is wireless, inexpensive, and automatic. There are other ways to get around using wires, including infrared communication. Infrared (IR) refers to light waves of a lower frequency than human eyes can receive and interpret. Infrared is used in most television remote control systems. Infrared communications are fairly reliable and don't cost very much to build into a device, but there are a couple of drawbacks. First, infrared is a "line-of-sight" technology. For example, you have to point the remote control at the television or DVD player to make things happen. The second drawback is that infrared is almost always a "one-to-one" technology. You can send data between your desktop computer and your laptop computer, but not your laptop computer and your handheld at the same time.
Bluetooth can connect up to eight devices simultaneously; however, it is limited in range to about 10 metres (or 32 feet). Bluetooth offers several security modes. In almost all cases, Bluetooth users can establish "trusted devices" that can exchange data without asking permission. When any other device tries to establish a connection to the user's gadget, the user has to decide to allow it. Service-level security and device-level security work together to protect Bluetooth devices from unauthorized data transmission.
"Bluejacking," "bluebugging," and "Car Whisperer" have turned up as Bluetooth-specific security issues. Bluejacking involves Bluetooth users sending a business card (just a text message, really) to other Bluetooth users within range. If the user doesn't realize what the message is, he might allow the contact to be added to his address book, and the contact can send him messages that might be automatically opened because they're coming from a known contact. Bluebugging is more of a problem, because it allows hackers to remotely access a user's phone and use its features, including placing calls and sending text messages, and the user doesn't realize it is happening. The Car Whisperer is a piece of software that allows hackers to send audio to and receive audio from a Bluetooth-enabled car stereo.
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Why is it called Bluetooth?
The name "Bluetooth" is taken from the 10th
century Danish King Harald Blatand - or Harold Bluetooth in English. During
the formative stage of the Bluetooth Trade Association a code name was
needed to name the effort. Over an evening discussing European history
and the
future
of wireless technology, several felt it was appropriate to name the technology
after King Blatand. He had been instrumental in uniting warring factions
in parts of what is now Norway, Sweden, and Denmark - just as the technology
is designed to allow collaboration between differing industries such as
the computing, mobile phone, and automotive markets. The code name stuck.
In Jelling, Denmark a monument can be found in a church yard that celebrates both his achievements and those of his father the first king of Denmark "Gorm the Old." Interestingly, this particular stone was lost for nearly six-hundred years after Harald had a small war with his own son, Sven Forkbeard, over control of the country. Sven "won" the argument (exiling his father in the process), and since this runic stone also glorified Harald, Sven had it buried. Only years later a farmer, curious about a large mound in his farm, rediscovered the stone.
The logo itself was originally designed by a Scandinavian firm at the time the trade association was announced to the public. Keeping to the traditions of the name, the logo combines the runic alphabetic characters "H," which looks similar to an asterisk, and a "B".