The Assessment Process

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The first step in planning a wireless strategy is to evaluate the existing corporate culture, networking environment, and users' needs. By talking to potential end-users you can discover their expectations, how they would like to utilize a wireless network, and a bit about what benefits a wireless network would provide them. In a corporation, for example, one group of users may be delighted to take a mobile computing device with them as they check inventory in the adjacent distribution center. Another group may be eager to use wireless networking capabilities during conference sessions. And still another group may be anxious to offer wireless networking to important corporate visitors.

In a corporation, you could classify the employees according to their job functions, since based on their job functions some end-users will derive more benefit from a WLAN than others. You can segment the WLAN user base into categories, such as executive management, engineering/product management, manufacturing, sales, marketing, and support.

Survey the potential user base about how they do their jobs. Have them provide an outline of their daily routine, and ask them to identify the difficulties they feel they encounter without wireless connectivity. Once that information is in hand, you will have a good foundation for determining whether a WLAN is right for your organization and if it can deliver an acceptable return on investment (ROI).

Then take a hard look at the impact of adding wireless networking to the current network environment. Make a list of the resources and people that will be affected by a wireless networking environment. This list should include WLAN technicians, network management software, upgrading and/or purchase of wireless computing devices, and more.

Also, before taking on a WLAN project, answer this question: Why is your organization considering wireless? Is there a need to implement (or expand) a mobile workforce environment?

Here is a suggested "wireless assessment check list" to help the reader plan his or her assessment strategy.

  • Can wireless devices operate within the current IT infrastructure? For example, does the existing backbone have sufficient bandwidth to handle the additional traffic of a WLAN? Are there enough ports available for the necessary access points? Will the access points (APs) interoperate correctly with the existing local area network's (LAN) routers and switches? While it's not strictly necessarily to use the same vendor for wireless as you do for your existing wired infrastructure, if the wireless components do not work properly with the existing network components, you're in trouble.

  • Is the technology consistent throughout your wired network?

  • How many users require mobility, and where do they need to go?

  • Will the WLAN support subscription-based users?

  • What user applications will the WLAN support and what performance levels do these applications require?

  • What is the corporate culture, and what are the goals for the WLAN? For instance, is it to bring more business to your location or to add an additional revenue stream? Or is it to gradually increase mobile employee support? If the organization has a substantial mobile workforce (e.g. a distribution center), supporting such a mobile force can have a significant impact on the company's information technology (IT) infrastructure. The mobile employee may need, for example, access to inventory management systems, corporate databases, company policies and procedures, the organization's email server, and customer support. If so, a WLAN is definitely worth investigating.

  • Does management want to support a mobile workforce to increase communication within the organization? If so, a WLAN is not a one-size-fits-all solution on how to improve communication within an organization. If the there is a lack of enterprise communication to begin with, no device in the world will fix the problem.

  • Is the push for a WLAN an effort to increase employee productivity? If so, how will the employees respond? Some employees are pleased that they are able to connect to the office 24/7. Others want to leave work behind when they leave the office. Forcing employees to maintain contact and availability can backfire by causing resentment or burnout. Evaluate the employee situation and formulate a strategy that respects the working environment as a whole.

  • Does the organization have both the financial and human resources to support a WLAN environment? The spending doesn't stop with the purchase and installation of the network and its components and computing devices. Resources will be needed for such things as training, employee technical support (24x7), lost devices, just to name a few. Supporting a WLAN environment can tax an IT department, particularly if it's already operating with minimal resources. Talk to the IT department and get the staff's opinion-the more they contribute to the decision process, the less likely they will be to protest later.

The assessment process lays the groundwork for the initial preparation for range, capacity, and coverage planning.

Range: You now know that every WLAN device is a transceiver, i.e. capable of both transmitting and receiving radio signals. This can, unfortunately, make predicting the range of a specific WLAN system in a specific environment challenging. Using identical components, effective system range may be well over 300 feet in one location and less than SO feet in another.

A number of variables, including building layout, construction materials and noise sources can affect transmission range. While some might consider the range limitations of radio to be its downfall, others understand that this very limitation is the main ally of a WLAN designer. That's because range limitations let you reuse frequencies (i.e. the same channel can be used in more than one cell, as long as the cells don't overlap in their coverage area), just like you do with conventional wireless services like FM (Frequency Modulated) radio. For example, say that WXXX FM in New York City is operating at 90.6 MHz. In all likelihood, careful design and technology has enabled at least one other FM station to use that same frequency in another locale within the state of New York. The FCC just requires that 100 miles or so separate FM stations using the same frequency.

Capacity: The same holds true for capacity. WLANs and 802.3 networks are shared-medium technology. With a WLAN, an access point (AP) is used to establish a coverage area within which an aggregate amount of throughput is shared by all wireless computing devices that access the access point(s). However, unlike a wired network, where the number of computing devices can be defined by choosing how many ports will be used on any one wire hub, a WLAN has no physical ports; only the size and shape of the coverage area defines the limits on the number of users accessing the network. So with a wired LAN, capacity planning can be absolute, whereas with a WLAN the user numbers vary. Not only are WLAN users mobile, entering and exiting the coverage area at will, but a WLAN's throughput is subject to variation as factors such as radio wave interference can decrease transmission rates.

When planning a WLAN's level of service, the goal is to provide end-user groups with the throughput rate they need to work efficiently and effectively. To reach this goal the deployment team must determine what are the average throughput requirements for each user group, and then how much throughput to provide to each group at any given time. Different groups have different throughput requirements. R&D departments, engineers in a manufacturing plant, and a graphical design group will required a higher throughput rate than a typical corporate office, which can get by with lesser throughput speeds. Distribution center employees and retail workers whose job requires that they use a WLAN to gather data via barcode scanners will need very modest throughput rates.

Coverage: The assessment process should provide the deployment team with the information needed to determine exactly where and what type of wireless connectivity is needed. For example, after the assessment process is completed it might be determined that the WLAN should provide connectivity in all conference rooms except those located in the accounting and human resources floors. Or that the WLAN should extend to the distribution center but not the loading docks.

When the requirements of the proposed WLAN can be clearly defined, it's much easier to choose the right Wi-Fi standard, plan a viable site survey process, and develop a realistic deployment plan. For instance:

  • Identifying the proposed WLAN users and their application requirements helps to define the network's technology and coverage areas, eliminating not only wasted money, but also security risks (by not sending signals beyond the necessary areas).

  • Listing the applications required by users will go a long way in helping to determine the WLAN's minimum bandwidth requirements and identify WLAN candidates. Keep in mind, however, that wireless is a shared medium, thus while most mainstream networked applications can be migrated to a shared WLAN, it's not necessarily appropriate for all applications (e.g. sensitive documents such as R&D, and human resources).

  • Once you know how many users the WLAN is expected to support and who these users are, it is relatively easy to determine which end devices the WLAN will serve directly. Then it's a simple task to establish which devices are already equipped with the correct radio NIC, and which need to be upgraded.

  • Doing a thorough assessment enables you to do a realistic estimate of what it will take-hardware, software, personnel-to deploy a WLAN in your organization and the estimated costs for the same.

You may use the results of the assessment study to compare a WLAN with an Ethernet alternative, perform a feasibility study for a specific mobile application, or provide the basis for a budget to present to upper management. Thus, an assessment study and determination of the WLAN's technology criteria not only saves networking dollars, but also can serve as the starting point in an increase in corporate productivity and end-user satisfaction.



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Going Wi-Fi. A Practical Guide to Planning and Building an 802.11 Network
Going Wi-Fi: A Practical Guide to Planning and Building an 802.11 Network
ISBN: 1578203015
EAN: 2147483647
Year: 2003
Pages: 273

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