Wi-Fi Planning: Do It Right the First Time
Effective planning can help businesses avoid barriers to a successful Wi-Fi implementation.
Wi-Fi installations keep growing. Not every IT department has the knowledge and experience to implement Wi-Fi without some problems: problems they create often due to having expectations of the technology that are simply not realistic. As with any IT endeavor, planning is critical.
I recently attended a one day seminar presented by Adtran on planning a successful wireless deployment. It provided an in depth approach to Wi-Fi technology and deployment. This blog focusses on the Wi-Fi planning.
There are four important conditions that can affect the operational success of a Wi-Fi installation:
- The Wi-Fi signal that goes between the clients/devices and the access points (APs) is impaired by the materials that are between the device and AP: walls, furniture, people, machines, and the air. The result is that the signal may not reach the device with enough signal strength to support a connection or acceptable throughput.
- An AP's available bandwidth is shared among all the devices that are connected and in use. This means that the more clients on an AP, the lower the available bandwidth to individual devices. There needs to be enough APs in a coverage area to support the capacity that the coverage area requires (office, classroom, conference room, huddle room, laboratory, and/or warehouse).
- There are other devices operating in the 802.11 frequency range that can interfere with and degrade the performance of the Wi-Fi network (cordless phones, IoT endpoints, security devices).
- There is more overhead in a wireless network than a wired one. Wireless networks usually require acknowledgements at the Ethernet, layer 2 protocol, which is not true in the majority of wired Ethernet connections. There is greater packet loss, as much 30%, which consumes bandwidth with retransmissions. The end result is that the usable bandwidth is about half the instantaneous bandwidth of 100Mbps, delivering a useful 50Mbps of bandwidth.
Before you buy and implement the network, you need to know how it will be used and what success means to the users. There will be different requirements depending on the type of business environment (i.e. campus, hotel, hospital, or business office). Some installations require low security, like a classroom, while others, such as a hospital, require high security.
A good first step is to determine how the network will be used. Questions you should ask yourself could include:
- Will the devices need low speed or high speed access? A cheap tablet from Walmart and PC notebook operate at about 1/10 the speed of a fast laptop PC or Mac.
- Will there need to be priority access and QoS for the devices? Voice is different than data. VoIP may not work well, but data may be fine on the network.
- Will there be video transmissions? If so, what resolution is required? The lower the required resolution, the less bandwidth you need.
- Will the devices be roaming among APs?
- You will need to determine the budget available and the cost of future upgrades. How many connections will there be and will they be simultaneous?
The Wi-Fi network is for the users, so you should ensure that the users are involved in the planning cycle. Ask questions that the users can answer. Do not be overly technical. If the questions are technical, educate the users about the technology question so they can understand the question and deliver well-considered answers. Here are some sample questions you should strive to answer:
- What devices do they plan on using on the network (especially BYOD)?
- What new devices are planned for the next three years?
- There are multiple versions of the IEEE 802.11 (a, b, g, n, ac) standard. Which of these do the devices support?
- What is the floor plan for the network coverage? Does it include outdoor access?
- Should all locations have the same coverage (conference rooms, offices, lobby, cafeteria, stairwell, between floors and buildings)?
- Are there any technical complaints about the existing networks, wired and wireless?
- Should all the users have the same access and security level?
- Are there any locations where an AP cannot be located?
- What applications are initially expected and will they change over the next three years?
- Do all of the devices and applications need to be supported on all the APs? If not, how are they divided?
The instructor for the Adtran seminar I referenced earlier emphasized one key point: The network planners must document everything -- requirements, restrictions, and budget. Wireless networks can encounter unexpected difficulties. The APs' locations may not be available or work as expected. The users may add devices that were not anticipated. Building materials may be incorrectly specified. Where wallboard is expected, there may be concrete instead. The actual AP Ethernet cable paths may be longer than allowed (over 100 meters). All of these potential roadblocks make the documents the definition of success.
If the network is not working properly, it may have nothing to do with the IT planning. Conditions may have changed, so the measure of success will also change.