As with any project, you need to carefully consider all costs of a wireless LAN before moving forward with deployment. You may use your resulting numbers to compare a wireless LAN with an Ethernet alternative, perform a feasibility study for a specific mobile application, or provide the basis for a budget you're proposing to upper management or a customer. In all of these cases, you need to take into account the hardware, software, and services necessary to install and support the system.
Let's take a look at what hardware to consider.
To help you prepare a foundation for assessing the financials, here are some questions related to the requirements and design:
- What applications will the wireless LAN support? What performance levels do these applications require? Will the wireless LAN support subscription-based users?
- Which 802.11 standard should you deploy: 802.11a or 802.11b?
- How many users, printers, and other end devices will the wireless LAN serve directly? How many of these devices are already equipped with radio NICs?
- How many access points do you need to cover the facility?
- Do you have an existing Ethernet network? If yes, how many ports are available for access points?
Answer these questions, and then start the financial exercise.
You need a wireless client ability of some sort for each user device, such as PDAs, laptops, PCs, printers, etc. More and more users are choosing wireless options when ordering laptops. So, you may not need to purchase a NIC for each user device.
Plan on paying on the average about $125 each for 802.11b radio NICs, and figure another 25 to 50 percent more for 802.11a NICs. I've seen 802.11b radio NIC prices as low as $49, however, and prices will fall more throughout 2002 and 2003. Unless you have unique application requirements, the user devices will not require any additional components that incur costs other than radio NICs.
If you're planning to use ad hoc mode (an 802.11 option), then you don't need any access points. In most cases, however, you'll be implementing an infrastructure network, which requires the use of access points. An access point links the wireless users to the wired network of file servers and Internet access. Multiple access points also provide roaming throughout a larger facility.
Access points vary in price, ranging from $300 to $2,000 depending on the features. For smaller office and home networks, you can get by with the lower-end, less costly access points under $200, but consider using the higher-end access points for enterprise solutions. The benefits you'll receive from the advanced features will likely make the difference cost effective.
An access point has limited range, and you'll need more than one to cover most facilities. An accurate method to determine the number of access points is to perform an RF site survey. You can employ an installation company or consultant to perform the site survey at a cost of approximately $1,000 per day, with a couple days necessary for a two or three story office building. Figure up to a week or so for larger facilities, such as hospitals and larger airports.
As a basis for determining preliminary costs before performing a site survey, plan on approximately one access point per 70,000 square feet of coverage area. This assumes a range of about 150 feet, but forms of attenuation and specific performance requirements may affect this value. You need to perform a RF site survey to obtain an accurate number of access points.
When installing a WLAN, include the costs for mounting the access points and running network cabling to each access point from an Ethernet switch or hub. For larger enterprise solutions, hiring a company specializing in wireless LAN installation will be well worth the expense. Each cable run will cost approximately $100 for each access point, depending on the scope of your network. Include another $150 or so per access point for installation and mounting hardware. You may also need to include some additional costs for installing radio NICs in user devices and making applicable configuration settings if needed.
A wireless LAN installation may require the addition of electrical wiring and outlets to power the access points. If you don't have an outlet within a couple yards from an access point, then include the cost of using an extension cord or running a new outlet to that access point location. The installation of each new outlet costs approximately $250. Extension cords are much cheaper ($15), but a professionally installed outlet looks better and offers a higher degree of safety. Of course you may be able to save the costs of adding electrical wiring by using power-over-Ethernet (PoE) technology.
In addition to the minimum hardware necessary, plan on having some spare hardware on site for replacing components that may become defective. With any system, it makes sense to have spares for elements that offer a single point of failure. For WLANs, the access point will cause the most havoc if it fails, at least for the users it serves.
With a spare, you can replace an access point within an hour or less. It may take 24 hours to replace one if you need to purchase a replacement. You need to make an assessment of the importance of availability and how long the network can be down, but it doesn't hurt to have at least one spare access point. Factor in the costs of these extras into your budget.
Wired Network Components
If you're implementing a public wireless LAN (i.e., hotspot), then include the cost of access controllers that regulate user access to the services that require subscriptions. You'll probably need one access controller per facility, unless you decide to have an additional one for automatic fail-over backup purposes. Access controllers vary in price depending on features, but plan on spending approximately $6,000 per access controller. Some access point vendors have the access control function built into the access point, which might be the best route to go if the network has very few access points.
Don't forget that with public wireless LANs, you'll also need to include costs for Internet connections as well.
If you're extending an existing Ethernet network to include wireless users, then there may be enough ports open on the existing Ethernet switches to connect the access points. If not, then include costs for some switches or hubs to interconnect access points. In general, each switch/hub can support up to eight access points and costs from $50 to several hundred dollars each depending on features. Similar to the access points, the more expensive Ethernet switches are needed for enterprise solutions in order to reduce support costs.
That pretty much sums up the hardware costs to consider. For the larger deployments, also include costs associated with project management and user training if applicable. And, don't forget the operational support element, such as network monitoring and problem resolution.
Jim Geier provides independent consulting services to companies developing and deploying wireless network solutions. He is the author of the book, Wireless LANs (SAMs, 2001), and regularly instructs workshops on wireless LANs.
Reprinted from 80211-planet.com.