Designing for Density
Mobile networks are being overwhelmed by the tremendous growth in data traffic that is being driven by smartphones and mobile attached laptops and tablets. Operators are looking at all the tools in their toolkit to address the network capacity challenge. One of the most interesting options is the use of heterogeneous networks (HetNets) based on Wi-Fi and LTE small cells. What makes this option so compelling, is that it provides a great deal of capacity through a high density AP footprint along with very high spectral reuse. These deployments can be targeted at hotspots like convention centers, city centers, arenas, stadiums, train stations, and the like that make up less than 20% of the area of a cell (or sector) and can easily generate 50% of more of the traffic.
One of the challenges with HetNets is that they require that networks be designed for both coverage and capacity. When designing for coverage the following rules will apply:
- Use lower frequencies as they propagate further. The 700 Mhz licensed bands are a great choice.
- Use a small number of very powerful base stations with antennas that are mounted on tall masts or roof tops
- Clear line of sight is desirable.
- Path loss is usually the limiting factor
When designing for capacity all the rules must change:
- Use a large number of very low power AP's deployed in very close proximity to each other.
- Use higher frequencies as they don't propagate as well as lower frequencies. The unlicensed 5 GHz band is a great choice.
- Line of sight is not desirable. You want obstacles, the more the better as the goal is to restrict RF propagation.
- Interference is the limiting factor when designing for density
- You can never have enough spectrum
- Narrow beam directional antenna enabled APs are an absolute necessity. The narrower the beam the better.
Ruckus has long been a leader in high-density Wi-Fi deployments. The cornerstone of our offerings has been our BeamFlex adaptive antenna technology which can focus RF energy at the user to increase gain and not at surrounding APs which will see this as interference. We are continuing to raise the bar in high-density networking with the announcement of the ZoneFlex 7782-N Access Point. It features an integrated 30° narrow beam antenna that operates in the 2.4 and 5 GHz bands. By integrating the antenna into the AP, the ZoneFlex 7782-N provides a very minimal form factor which is essential in many deployments.