Stadiums represent an unparalleled challenge to wireless operators in terms of the density of mobile device users. Tens of thousands of people are concentrated in a very limited space including the bowl of the stadium and surrounding areas like parking lots, offices, access hallways, bars and restaurants. It’s a matter of fact that in order to address such huge traffic demands, the available spectrum needs to be reused as much as possible. This means the number of sectors required for a distributed antenna system (DAS) can get extremely high, considering a single sector can typically serve around 1,000 people.
Cowboys Stadium, Dallas, Texas
Unfortunately, the more cells that operate on the same frequency in a given area, the higher the generation of inter-cell interference. Several experiences from the field have proven that the power spillover from one sector to neighboring ones can be quite substantial. You also have to cope with external interference coming from surrounding macro base stations. All of that can produce a severe degradation of the signal quality with a consequent reduction of the total delivered capacity.
Antenna technologies play a crucial role in overcoming the issue of interference containment. Ideally the antennas should allow for sculpting the radio waves so that each sector footprint only covers a well-confined zone of users. In order to achieve that, antenna radiation patterns with a steep cut-off outside the main lobe need to be exploited. It is even more difficult to meet these antenna specifications over a large frequency range. In practice, inter-sector interference can be mitigated adopting the right antenna products with proper orientations.
CommScope recently released two antenna products specifically targeted for high capacity venues. These are Cell-Max™ DM60 and DM30 directional cross-polarized MIMO antennas with 60° and 30° 3dB radiation patterns, respectively. They combine a consistent narrow beamwidth with an ultra wide frequency range. They also feature smart mounting brackets with an audible click, enabling flexible orientation and simple adjustment of both azimuth and elevation angles.
What other solutions help lessen the severe burden on wireless infrastructure in extremely high capacity venues like stadiums?