The wireless data industry in South Africa is growing. With the deployment of next generation carrier networks, advancements in wireless technology, and the adoption of the Internet and intranet wide area networking, having instant access to information is quickly becoming reality for mobile staff.
Implementing the technology itself or embedding wireless modules that integrate with your hardware applications, from point-of-sale devices to ruggedised laptops/handhelds, allow computing devices to become powerful communications tools. But what is the technology behind this wireless revolution?
The two main options available are a wireless LAN (local area network) or a wireless WAN (wide area network). These technologies are similar in that they both allow users to access data on their PCs or PDAs without using network or modem cables.
Comparing LANs and WANs
Wireless local area networks by definition operate over a small, 'local' coverage area, normally about 100 m. They are typically used in buildings to replace an existing wired Ethernet, or in a home to allow multiple users access to the same Internet connection. Other wireless LAN coverage areas can include public hotspots in coffee shops, hotels, or airports.
Wireless wide area networks cover a much 'wider' area, essentially wherever the cellular network provider has wireless coverage. Typically, this is on a regional, nationwide, or even global scale. Using a wireless WAN usually gives the user access to data wherever they go and is one of the biggest advantages of a wide area network.
Speed
The 802.11b wireless LAN standard transfers data at speeds of up to 11 Mbps, with typical rates of between 1-4 Mbps, decreasing as more users share the same wireless LAN connection. The latest version, 802.11a, is supposed to transfer data at speeds of up to 54 Mbps. One concern, however, is that as more people or businesses use wireless LANs in close proximity, the frequency band can get crowded and slow performance down.
Wireless WAN speeds differ depending on the technology used. GPRS networks offer maximum user data rates of over 115 Kbps if all eight timeslots in a cell are allocated for data transmission. However, a realistic and consistent user data throughput rate of 30-50 Kbps is expected and seen in practice, when four timeslots are used, as currently supported by most networks.
Data speeds on CDMA networks were initially available at speeds of 14,4 Kbps, but have increased to a maximum throughput of 153 Kbps as carriers have implemented CDMA1X networks. This gives the user typical throughput speeds of 40-70 Kbps, in addition to doubling the voice capacity of the carriers' network.
Newer wireless WAN technologies, like CDMA 1xEV-DO, provide peak data rates of up to 2,4 Mbps in a standard 1,25 MHz CDMA channel. UMTS, also known as WCDMA (Wideband CDMA) is another approved next generation standard which uses one 5 MHz channel for both voice and data, offering data speeds up to 2 Mbps.
Data security
Security is one of the most important features when using a wireless network. Security is one of the biggest strengths for cellular wireless networks (WWANs) and one of the biggest weaknesses in 802.11 networks (WLANs).
There are some inherent security weaknesses in 802.11 networks, however, cellular wireless WAN networks are extremely secure. These networks incorporate military technology and sophisticated encryption and authentication methods.
Wireless LANs have some inherent security weaknesses:
* The authentication process, even where security is increased using shared key authentication, is not considered secure.
* The difficulty in restricting physical access to the network, because anyone within range of a wireless access point can send, receive, or intercept frames. WEP (Wired Equivalency Protocol) was designed to provide security equivalent to a wired network by encrypting the data sent between a wireless client and an access point. However, key management is a significant problem with WEP. WEP keys must be distributed via a secure channel other than 802.11.
* When security features are turned on, there are problems with interoperability between wireless LAN modules from one vendor and wireless LAN access points from another vendor.
Hotspots
Hotspots are wireless LANs available to the public in a location like an airport, coffee shop, or city neighbourhood. These (hotspots) enable users to access the network either free of charge, or for a fee paid to the network operator. These networks are being deployed by individuals, wireless LAN operators, and even cellular operators as a way of complementing their existing cellular networks for data users.
Although the coverage of hotspots is limited, they provide an alternative wireless method of publicly accessing data. Obviously, security should be a major concern when using a wireless LAN in a hotspot, since there may be no security on the public, shared network.
Costs
Since wireless LANs operate in the unlicensed frequency range, there is no service cost for using a private wireless LAN (such as in a corporate office or home office). There will be a monthly Internet service provider cost for accessing the Internet through your wireless LAN access point (through a broadband or cable connection). The other costs involved are the cost of purchasing and installing the wireless LAN equipment and devices, and the cost of maintaining the network and the users. Public hotspot network providers typically charge fees for access.
For cellular wireless WANs, the cellular network operator is acting as your Internet service provider by providing access to the Internet over its network. The cellular operator therefore charges a monthly subscription rate to its network, similar to a wireless phone subscription. This may be a flat monthly fee, or it may be calculated according to either the amount of time connected to the network, or the amount of data transferred.
Do WWANs and WLANs work together?
Although wireless LANs and wireless WANs may appear to be competing technologies, they are each valuable and can be seen as complementary technologies. With access to both, a user would have the best of both worlds: the ability to use high-speed wireless access from a hotspot in a campus area, and the ability to access all their data and applications with cellular access from a much wider area.
When considering wireless LAN and wireless WAN technologies, it is important to note the differences between them and ensure that you choose the right technology for your specific application. Both of these wireless technologies have great advantages when used in the right application, and can complement each other when used together.
For more information contact Craig Cottrell, Leaf Wireless, +27 (0)11 326 1844, info@leafwireless.com, or Sharlene Myers, Sierra Wireless, smyers@sierrawireless.com
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