Maintaining Coverage, Capacity and Performance in
Dense Urban and Coastal Areas

The Situation

The 2010 census is expected to show US population over 310 million, representing 10% growth over the last ten years. With wireless penetration now at 93% of the US population according to CTIA, growth in population is one factor driving significant reliance on cellular networks. Other factors include the heavy use of data-intensive applications (90 petabytes of data are used globally per month, equivalent to 23 million DVDs) and growing substitution of wireless for wireline phones, now at 22.7% of U.S. households compared to 8.4% four years ago. Dense urban areas provide challenges to wireless operators:

  • Support traffic from a very large number of subscribers.
  • Provide features and service quality to compete with many other providers attracted to the high revenue opportunities in these areas.
  • Maintain network performance while faced with a variety of co-channel and adjacent channel sources of RF power.

Coastal areas, with only 17% of contiguous land area but more than half of the US population, present the same challenges as other densely populated areas, and also typically have a more complicated interference problem due to sources on the water (bi-directional amplifiers) and across the water (competing providers in the same band).

The Resolution

When narrow band co-channel interference occurs, the physical layer is impaired. Immediately channel power is increased and the coverage area and data throughput are reduced. For CDMA cell sites not at capacity, traffic will be diverted to other CDMA carriers. But, during high-traffic periods when the cell site is operating at capacity there is no margin or excess capacity available to compensate for interference. In these situations the impact is immediate. Capacity is reduced, dropped calls increase, ineffective attempts increase, data throughput and data rates are reduced.

For UMTS this situation is more significant. Once co-channel interference occurs, channel performance is immediately degraded and in cases where there is not another UMTS carrier or the other carrier is already at capacity, the degradation will be severe.

Through RF Digital Signal Processing, the technology in ISCO's Proteus® product, co-channel interference is automatically, adaptively removed and service levels along with capacity are recovered immediately. Adding Proteus® to a cell site has been shown to provide 63% improvement for the entire cell site, when measuring KPIs such as calls and Erlangs before and after ISCO's deployment. Realizing that level of increased capacity in multiple cell sites throughout a wireless network makes a carrier much more prepared to handle the huge volumes of traffic expected in densely populated areas.

Infrastructure Details

Now that ISCO's Proteus® with RF Digital Signal Processing is available, smaller guard bands and offsets to increase spectrum available for carriers is possible. Mitigating co-channel interference, whether random or self induced, can recover vital capacity being unnecessarily wasted. And actively conditioning high-profile, high-traffic sites from the statistically determinable occurrence of co-channel interference or high-power adjacent RF can maintain capacity, performance and throughput.