In today’s era, immediate access to the Internet is not just a convenience – it’s expected. Wi-Fi access used to be something offered by coffee shops and certain restaurants, but now users expect access regardless of their location. Shopping malls, airports, convention centers, auditoriums, high-rise buildings, and sports stadiums are just a few places where providing wireless connectivity presents unique challenges. The problem faced by most IT providers is designing a high density wireless network that provides instant access for users, at the right bandwidth speeds, and with the security needed to protect individual devices.
What Makes a High Density Network Different from Standard Wi-Fi?
There are two main issues during network infrastructure design phases: the number of users within a certain area (density) and coverage area. High density networks ensure users are able to have sufficient throughput regardless of the thousands of other users within close proximity. This is one of the primary issues in venues such as stadiums and auditoriums where massive amounts of users need Wi-Fi access within close proximity of each other.
Coverage area is also a concern, although not as significant an issue as high-density bandwidth access. Most networks offer a limited coverage area that spans only the immediate location and signal degradation isn’t a concern once the user leaves the venue. The bigger concern is that current network infrastructure won’t be able to handle the traffic spike. Both the wireless and wired network need additional resources.
Regardless of the location, high density networks are increasingly necessary as today’s users have more than just one mobile device. This means that accounting for number of people isn’t enough to cover the number of devices that need connectivity. It’s not uncommon for users to have at least two devices and possibly a third. Think of the reporter at a local sports stadium. He could have a smartphone, a tablet, and a laptop that all require network access to report the event real-time. Multiply this reporter by several thousands more users and your network could easily become overloaded.
These networks are usually reserved for venues where the expectation is that there will be thousands of users within a confined area. It can be only on specific dates such as concerts and sporting events or it can be a consistent occurrence such as airports and corporate buildings.
Implementing the Right Resources
As with any high capacity network, you need the right resources to provide services to your users. When you design these networks, you’ll probably have higher loads of users in certain areas even within the confinement of the location. It’s these areas you should be most concerned with.
Review the Site Environment
Before designing anything, go onsite to review the environment to identify any interference possibilities. Radio towers, current APs, and high-powered electronics can interfere with a wireless signal. You can create a design that avoids these interference points, leverage shielding from concrete overhangs or roofs, or convince the customer to relocate resources that could cause signal degradation. Just remember that any current interference points must be considered in the network design.
Implement Dual Access Points
Once you define the areas with the most density, the first step is to provide dual access points (APs) or at least multiple access points within a certain range. You want to offer enough APs to provide connectivity for all users, but don’t place them too close where they interfere with each other. These access points should range from 2.4GHz and 5Hz. Best practices call for 3-4 APs for your wireless users. When one AP overloads, the client can then fail over to another. However, your failover should be limited. You only want approximately 50 devices for each AP, although you can stretch it to 100. Never allow more than 100 devices to connect to one AP to avoid performance issues. Additional factors of concern are:
- Receive strength
- Transmit strength
- Placement and angle of antennas
- Minimum transfer speed
Load Balance Your Users
Similar to a web farm, your APs will fill up to capacity quickly in high density areas. Load balancing involves directing user traffic to an AP that isn’t overloaded. The technique evenly distributes network traffic across APs, so no one AP is completely filled to capacity while the others have no users connected.
Leverage Overhangs, Ceilings and Roofs
Antennas placed at strategic points where users congregate can offer direct frequencies that provide better throughput and signal strength. Place antennas in areas where users will likely need wireless access. By leveraging overhangs and ceilings, you can offer high density APs that even mold well with the aesthetic environment.
Place APs in Rooms Separated by Concrete
Overlap and interference are problems when designing an infrastructure that provides high density coverage. You need to provide plenty of APs, but these APs interfere with each other when they are too close together. This can be avoided by placing APs in rooms separated by concrete. Concrete absorbs radio frequency energy, so an AP’s signal won’t interfere with any APs in the next rooms.
Upgrade Your Wired Network
Most APs tie in with hardwired networking that sends the signal to the Internet or another internal network. Your hardwired network must also be able to handle the bandwidth. Hardwired sections of the network are often neglected and can be a bottleneck. If you plan to greatly increase the user capacity on a network, it’s time to upgrade switches to 1G or 10GB capacity.
Stress Test the Network Before Users Do
Official deployments should always include some time to stress test the network. There are plenty of applications on the market that can help you, but you should always stress test your network resources before you unleash the upgrade on the public. You don’t want to find out that your network can’t handle the increased traffic on the official day it’s used. Always add time to the project to allow for stress testing and the possibility that the current design won’t pass.
Summary
High density wireless networks require a degree of expertise to manage your users and equipment. These best practices ensure that your design meets customer expectations during your next deployment. IT administrators familiar with simple wireless setups might find this design much more advanced, but supporting thousands of users as opposed to a few dozen requires additional resources and equipment that can handle the massive spike in traffic.