Wireless LAN Deployment Steps

As part of planning a wireless LAN deployment, you need to define the tasks
necessary for completing the project. This involves realizing applicable steps,
such as requirements analysis, design, and installation, which are common to
any system solution. To minimize deployment
risks
and ensure a successful project, be sure to address the following
steps as they relate to wireless LANs:

  • Requirements. Before getting too far with the project, understand
    as much as possible about requirements, such as needs of users and applications,
    interfaces with existing systems, facility composition, and so on. This provides
    the basis for making decisions when designing the solution. If you don’t do
    a good job of defining the requirements, then the solution may not meet the
    needs of users.

    For smaller networks, the requirements gathering process could be as simple
    as spending a couple days thinking about requirements and preparing a two to
    three page document that defines them. Larger systems, however, will likely
    need for a more involved process because of a broader base of users and systems.
    If requirements are not well understood, then consider using prototyping and
    construct a solution based on known requirements. The testing of a small prototype
    with a limited number of users will often lead to better understood requirements.
    We also have details
    on defining requirements
    .

  • Design. The design produces a definition of how the wireless LAN
    will satisfy requirements. This includes technical elements such as developing
    the system architecture, identifying standards (e.g., 802.11b or 802.11a),
    selecting an access
    point vendor
    , specifying antennas
    types
    , identifying MAC
    Layer
    settings, and so on. The end result of the design will be a bill
    of materials and diagrams that indicate the interconnection of related software
    and hardware components. Of course this leads to the cost of the system, something
    important to know before moving on.

    Be sure to perform an RF
    site survey
    to determine the optimum location and number of access points.
    Also investigate the presence of RF
    interference
    and recommend appropriate countermeasures to maximum the performance
    of the network. In larger more complex networks, consider the use of a simulation
    (e.g., OPNET), which leads to making better
    decisions on access point settings based on various user activity and network
    configurations.

  • Feasibility. Once the requirements and design are known, it may be
    worthwhile (and required by some companies) to perform a feasibility analysis
    before spending the money to purchase components and install the system. The
    idea is to identify benefits and determine whether the costs of the system
    will result in a positive return on investment. For some applications, such
    as inventory management and price marking, gains in efficiency and accuracy
    are relatively easy to define with well understood costs savings and rapid
    returns on investment. The deployment of a wireless LAN in a corporate environment,
    though, may be more difficult to defend in terms of user efficiency cost savings.
    In this case, focus on ease of installation and long-term support cost savings
    in addition to meeting needs for mobility. Get more details
    on the feasibility of wireless LANs in offices
    .
  • Development. Some wireless applications require the development of
    client software to implement certain functions. For example, requirements
    may call for the utilization of handheld data collectors with built in scanners
    to perform inspections throughout a manufacturing plant. Users may scan a
    bar code at a particular point and answer question prompts on the data collector.
    This application would likely require custom software. In these cases, programmers
    must fully understand wireless impairments such as RF interference and limited
    coverage in order to include appropriate error recovery mechanisms. A wireless
    LAN is often referred to as transparent to the user, but this is only if the
    programmer takes into account issues related to wireless connectivity.
  • Installation and Testing. The installation phase of the project is
    when the tires hit the pavement. If the design is done effectively, then the
    installation should be a smooth process. For example, the design should specify
    where to mount the access points. It’s generally best to place the access
    points as high as possible, but be practical. Warehouses have high ceilings;
    however, avoid mounting the access points so high that you need expensive
    equipment to reach them. Also, consider using Power over Ethernet (PoE) to
    run electricity to the access points. This avoids the time and costs of installing
    electrical outlets throughout the facility.

    After completing the installation, be sure to test for proper operation and
    coverage using 802.11 analyzers such as those from Airmagnet,
    Berkeley Varitronics, and Wildpackets.
    The testing may indicate the need to move some access points and possibly use
    different settings. Be certain to document access point locations and configurations
    if changed from the design. This will provide an aid to the people when supporting
    the operational system.

    In order to reduce risks in larger system deployments, think about starting
    with one or more pilot sites to test the solution with a limited number of users.
    The feedback from users during the pilot testing will often uncover problems
    with the design. Keep in mind that it’s much less expensive to fix a problem
    with the design before installing the system throughout the entire company.

  • Operational Support. Before allowing users on the network, ensure
    there’s definition and activation of adequate operational support. This includes
    elements such as trouble resolution (e.g., help desk and technical support),
    periodic maintenance, and system monitoring. What most people don’t realize
    is that this phase of the system’s life can be much more expensive than the
    cost of the installation. As a result, define enough details of the support
    elements to provide an ongoing budget.

    To ensure effective support, be sure there’s a single phone number to call
    if problems arise. In most cases, this requires that the wireless users call
    an existing support system; however, be sure that the support providers understand
    how to handle peculiar wireless problems. Impairments, such as RF
    interference
    and multipath
    propagation, can baffle support staff not familiar with wireless LANs. The support
    staff will also need to fully understand the wireless LAN configuration and
    settings and have appropriate test tools to effectively troubleshoot and fix
    problems.

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.

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