Some of the most challenging Wi-Fi installations are those involving very high client density. This can be anything from a classroom with many students connecting to a single AP for multimedia teaching aids, to an indoor event hall with hundreds of participants, to a stadium with thousands of fans looking to share their experience by uploading pictures etc.
Cambium cnPilot APs have been used in several such deployments, a few notable examples are:
Reboot Infogamer event in Zagreb, Croatia
Success in a high density installation is measured by client peformance: how good was the user experience as they browsed, used various applications etc; how well did the APs provide service to each of the 50 or 100 clients all connected to it.
Of the several factors that matter in such a topology a few key ones are:
AP hardware selection
From Omni directional antennas, to wide beam (90-120 degree) sectors to narrow beam sectors (30 degree) the correct AP type must be used, based on the application. Typically in a stadium stand you would use the narrow beam sector APs (Eg: cnPilot e501S), while say in the media room you would use a omni indoor AP such as the cnPilot e600.
Bandwidth provisioning and management
It is important to ensure the bandwidth expectations per-client are accomodated in both a per-client rate limit (configured in WLAN settings) as well as the total backhaul bandwidth available at the site. Without this, bottlenecks can form quickly either at the AP or on the backhaul connection to the site, in both cases causing the client experience to suffer. In addition, having redundant backhaul links will help mitigate the impacts of outages of the main backhaul connection to the site.
Planning and Installation
One of the most important phases of rolling out such a network is the planning. This starts with RF-planning and site-surveys to ensure optimal coverage as well as identifying the location of AP installs. The next step is mounting the AP. While cnPilot APs support many standard mounting schemes (wall, T-bar ceiling etc for indoor, pole and wall for outdoor) some locations require fabrication of specialized mounting arms. In addition the planning should take into account wired connections throughout the site are taking into account performance and redundancy. The backhaul is also typically hierarchical, from access to core switches and finally leading to a gateway/router; all this should be carefully planned out.
Optimal Configuration
Configuration of the network devices matters all the way from the APs to the switches, to the DHCP server. What size DHCP pool to use, whether VLAN pooling is required on the SSID, whether RF parameters have been optimized, all play a critical role. Some of the RF tweaks for high density include:
- Using 20MHz channels on 5GHz radios so there are enough available channels with minimal interference.
- Turning off lower data rates (1Mbps, 2Mbps almost always. Sometimes everything below 9Mbps or 12Mbps) to better utilize airtime.
- Using ACLs to filter out broadcast and multicast traffic that is not needed on the air
- Consider turning off some 2.4GHz radios on APs closely placed.
- Using airtime fairness and band-steering to increase the efficiency of the network.
In summary, careful planning and deployment are the keys to success in a very high density Wi-Fi install. Cambiums cnPilot Enterprise APs provide a range of outdoor and indoor solutions for such deployments. These APs can be managed through the single pane of glass: the cnMaestro controller, providing administrators the control and insights needed into such a network.