For information on how to configure your computer to connect to the wireless Internet at UNC, please visit our Connecting to the UNC Network – Getting Started document.
Wi-Fi is a specific type of wireless technology based on specifications standardized by the Institute of Electrical and Electronics Engineers (IEEE) standards committee (the 802.11 group). Accordingly, all Wi-Fi products are referred to as 802.11-something. Wireless network technologies encompass a broad range of products, including Wi-Fi, cellular, Wi-Max and more.
Wi-Fi Coverage Issues
Wi-Fi access depends on many factors: proximity to a wireless access point (WAP), total number of users and total traffic, wireless card transmission power, and sources of wireless interference. Although Wi-Fi access is considered newer technology, it’s not necessarily the best method of Internet access. Wi-Fi connection speeds range from 11Mb/sec up to 54Mb/sec, although the typical speed is much lower. At UNC Chapel Hill, most wired connections are 100Mb/sec or 1000Mb/sec. A wired connection to the Internet is typically much faster, more secure and has no interference issues. While you use the Internet over a Wi-Fi connection, your data is sent through the air and is only as safe as the level of security encryption that you use. The difference between a wired network connection and a Wi-Fi connection is similar to the difference between registered mail and a postcard.
Wired vs. Wi-Fi
If you have the option between being connected to a wired network port versus a Wi-Fi one, choose the wired port and enjoy the faster and more stable connection.
- Proximity to Wi-Fi access points (WAPs): The first requirement for Wi-Fi access is to be within range of a WAP. Please visit the Wireless Network Access Points document for the specific locations of UNC Chapel Hill WAP. The closer you are to each WAP, the higher your chance of receiving a strong signal. The typical range for Wi-Fi connectivity indoors is usually 50 to 150 feet, depending upon building materials and other physical barriers. In most cases, if a WAP has been installed in a specific lounge/office, we cannot guarantee coverage outside of that room. In places like Odum Village, which have no wired access and only Wi-Fi, it’s very common for the apartments furthest from the WAP to have coverage issues in the corner bedrooms, but decent coverage in the common rooms.
- Number of users and traffic: For most 802.11b/g WAPs, service begins to degrade when 30-40 users connect. This is a guideline and if all 40 people are simply reading a website, then you shouldn’t notice any problems. If however, each person is using high bandwidth, then the service may begin to degrade after only 20 people are connected. For this reason, we highly recommend that Wi-Fi users not use peer-to-peer software like Skype, BitTorrent, or any of the many file sharing software applications.
- Radio Frequency Interference: Radio frequency (RF) interference involves the presence of unwanted radio signals that disrupt normal system operations. Because of the way 802.11 (Wi-Fi) works, an interfering RF signal of certain characteristics can appear as a bogus 802.11 station transmitting a packet. This causes legitimate 802.11 devices to wait for indefinite periods of time until the interfering signal goes away.
- Wireless Card transmission power: All Wi-Fi cards are not created equal. Typically, cheaper cards have a lower transmission power, which means that they must be closer to the WAP than higher powered cards (~30mW). Keep in mind the saying “You get what you pay for.”
Wi-Fi APs, specifically 802.11b and 802.11g both use the shared 2.4GHz wireless band. Other devices that operate in this band can prevent Wi-Fi from working or severely degrade the service.
- Unauthorized Wireless Devices: One major interference source is unauthorized wireless devices, most commonly wireless routers. These devices can disrupt the service for neighboring WAPs. They also pose a security risk, because anyone who connects to the unauthorized APs has no assumption of security. ITS will attempt to track down and disable any unauthorized wireless device if they are disrupting service. This is by no means a trivial task because many of them are not on all of the time.Computers can also become a Wi-Fi ad-hoc device, where they act as a relay for other devices to connect to the Internet. We recommend disabling this feature because both the host ad-hoc device and all connected devices will have a much slower connection.
- Cordless Phones: Cordless phones operate on many different frequencies. You can typically find out which frequency your phone uses by simply reading the labels. They include the following: 900MHz, 2.4GHz and 5.8GHz. A computer using Wi-Fi will have connection problems if anyone is using a 2.4GHz phone in the area.
- Microwaves: Another device that causes interference with Wi-Fi devices are microwaves. Now, we aren’t saying that you should never use a microwave again. Most microwaves are designed to contain their “microwaves” within the device. The coating on the glass door is made to do this. From time to time there are microwaves that leak and these can cause problems. Most computers that are within 10 feet of an operating microwave will experience slow connections.
- Bluetooth: Finally, devices that use Bluetooth like laptops and cell phones can also interfere with Wi-Fi access.
Wi-Fi Frequently Asked Questions
What can I do if I’m having problems?
If you know that you’re within range of an AP, then your problem may be specific to your computer or an interference issue. We recommend you contact ITS for help isolating the issue. Because there are many factors related to Wi-Fi access, you may need to meet with an ITS representative to gather enough data to solve the problem.
Why doesn’t the entire campus have Wi-Fi coverage?
Installing Wi-Fi on campus is not as easy as buying a $40 wireless router from your local electronics store. The typical access points that UNC uses, cost $900, not including the installation and management costs. What’s the difference? About $860. A home environment tends to be a more controlled environment than either an enterprise like a university or a community network: fewer users, fewer types of applications, and knowledge of who is connecting to the network. An enterprise or community environment, however, requires a greater feature set and functionality than products meant for the home/single family use. These include:
- Virtual Local Area Network (VLAN) support – allowing for segmentation of various user groups, accommodating clients with different security requirements and capabilities
- Quality of Service (QoS) – prioritizing traffic for different application requirements, necessary for voice and video performance
- Fast/secure roaming – allowing authenticated clients to roam securely from one access point to another without perceptible delay
- Client tracking – using radio management information to provide near-real-time tracking information
- Advanced encryption and user authentication standards, including TKIP and AES, 802.1X and EAP-based authentication, support for RADIUS server user registries
- Scalability and extensibility
- Configurable transmit power
- Load balancing
- Support for 802.11a/b/g/n
- Support for inline Power over Ethernet (PoE)
As funds and the needs arise, we install wireless access points in many locations on campus to cover common areas outside, in buildings and residence halls as well as offices and classrooms. In most cases, this service is meant to supplement the wired network.
Are there any health safety issues with Wi-Fi?
To date, no health risks have been found or verified in association with these specific radio frequency fields, unless of course you’re online playing EverQuest 24 hours a day.