Most Wi-Fi deployments are set-up to deal with a relatively low number of concurrent users, often only 10s or 100s of users in a fairly wide area such as a cafe or an office. This approach is straightforward requiring a small number of wireless access points. At many events the level of concurrent users may easily be in the thousands and typically in highly concentrated areas. To provide a good service to this density of users requires a much more complex approach.
The challenge is because an individual wireless access point can only support a limited number of users, even a high-end professional unit will only service around 100-200 users in an effective way depending on the type of usage. However, it is not quite as simple as just adding more wireless access points because unless careful attention is paid to the design the wireless access points will interfere with each other and lead to more problems.
Many large Wi-Fi deployments suffer from poor design leading to a bad user experience, true ‘high density’ design requires careful analysis of wireless spectrum and often uses special equipment to control the spread of wireless signals.