Access Point
From Network Dictionary Wiki
Access points act as a central transmitter and receiver of WLAN radio signals. Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards.
Low-cost and easily-installed WAPs grew rapidly in popularity in the late 1990s and early 2000s. These devices offered a way to avoid the tangled messes of category 5 cable associated with typical ethernet networks of the day. Whereas wiring a business, home, or school often requires stringing many cables through walls and ceilings, wireless networking offers the ability to reduce - or eliminate entirely - the stringing of cables. Wireless networks also allow users greater mobility; freeing individuals from the restrictions of using a computer cabled to the wall. In the industrial and commercial contexts, wireless networking has had a big impact on operations: employees in these areas now often carry Portable Data Terminals integrating barcode scanners and wireless links, allowing them to update work-in-progress and inventory in real-time.
Limitations
Most jurisdictions have only a limited number of frequencies legally available for use by wireless networks. Usually, adjacent WAPs will use different frequencies to communicate with their clients in order to avoid interference between the two nearby systems. But wireless devices can "listen" for data traffic on other frequencies, and can rapidly switch from one frequency to another to achieve better reception on a different WAP. However, the limited number of frequencies becomes problematic in crowded downtown areas with tall buildings housing multiple WAPs, because enough overlap can occur between the wireless networks to cause interference.
Wireless networking lags far behind wired networking in terms of increasing bandwidth and throughput. While (as of 2004) typical wireless devices for the consumer market can reach speeds of 11 Mbit/s (megabits per second (IEEE 802.11b) or 54 Mbit/s (IEEE 802.11a, IEEE 802.11g); wired hardware of similar cost reaches 1000 Mbit/s (Gigabit Ethernet). One impediment to increasing the speed of wireless communications comes from Wi-Fi's use of a shared communications medium, so a WAP can actually use somewhat less than half the actual over-the-air rate for data throughput. Thus a typical 54 MBit/s wireless connection actually carries TCP/IP data at 20 to 25 Mbit/s. Users of legacy wired networks expect the faster speeds, and people using wireless connections keenly want to see the wireless networks catch up.
Interference can commonly cause problems with wireless networking reception, as many devices operate using the 2.4GHz frequency. A nearby wireless phone or anything with greater transmission power within close proximity can markedly reduce the perceived signal strength of a wireless access point.
Security
One issue with wireless access in general involves the need for security. Many early access points could not discern whether or not a particular user had authorization to access the network. Although this problem reflects issues that have long troubled many types of wired networks (it has been possible in the past for individuals to plug computers into randomly available Ethernet jacks and get access to a local network), this did not usually pose a significant problem, since many organizations had reasonably good physical security. However, the fact that radio signals bleed outside of buildings and across property lines makes physical security largely irrelevant to war drivers.
In response, several new security technologies have emerged. One of the simplest techniques involves only allowing access from certain MAC addresses. However, client devices can easily spoof MAC addresses, leading to the need for more advanced security measures. Many access points incorporate Wired Equivalent Privacy (WEP) encryption, but security analysts have criticized WEP's inadequacies, and the U.S. FBI has demonstrated the ability to break WEP protection in only 3 minutes. Newer encryption standards available on wireless access points and client cards include Wi-Fi Protected Access modes WPA and WPA2, both of which offer substantial improvements in security. Also, a newer system for authentication, IEEE 802.1x, promises to enhance security on both wired and wireless networks. Wireless access points that incorporate technologies like these often also have routers built in, thus becoming wireless gateways.
Some advocates are arguing that one can as well leave the access point unencrypted and open; if every private access point would be open for the public, it would be easy for anyone to find internet access while beeing on the road. The arguments and security issues are also discussed in the Wireless LAN article.
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