Field insights: Small cell network optimization
If a large enterprise has multiple buildings and a complex interior, it presents extra challenges for wireless performance. But a small cell solution can improve in-building performance significantly — particularly when advanced tools and expertise are available during small cell network optimization and design.
That’s what enabled 25 small cells to deliver exceptional KPIs for a financial center comprising 218,000 square feet, across 3 buildings on multiple levels. In this complex environment with exterior glass walls, the following improvements were achieved for indoor coverage and capacity:
- 3G indoor signal coverage improved from 8% to >95%
- RF signal quality increased from 11% to 95%
- Overall 3G voice and data coverage was enhanced by 90%
- Voice and data setup success rates were better than 99.7%
- Voice and data dropped-call rates decreased significantly — while maintaining a handover success rate of 99.6%
The following field insights are provided by experts familiar with the 3 biggest challenges of this large enterprise small cell deployment. In each case, a solution starts with network design using different tools and expertise. Then optimization fine-tunes the original design to further improve wireless performance.
1. Detailed guidelines that meet intricate coverage requirements
The large enterprise in this case sprawls across 3 buildings, including a building with 10 floors. But not all floors needed wireless coverage. To deliver precisely what was needed, experts used network design guidelines that were flexible enough to target the right in-building areas — while limiting coverage elsewhere.
Their knowledge and experience were also important for establishing initial power settings and antenna placements during the design phase. These design choices were verified later, in the optimization walk. And some settings and placements were adjusted, as necessary, to create the most effective coverage boundaries.
2. RF tools that minimize interference
The financial center’s exterior walls are made of glass, which allowed the strong macro signal to penetrate from outdoors. And the indoor RF signal could also leak to the outside. Therefore, optimal power settings had to be determined to avoid interference to both the macro and small cell networks.
The 1st step was to model the building materials carefully during the network design phase. This process used specialized prediction models and in-building design tools, such as an RF tool that allows each material to be modeled with its own attenuation characteristics. The goal was to establish an “ideal” power for each small cell. This setting would give the small cell signal dominance over the macro inside the building, while not causing interference outside the building.
The balance of signals was then verified and optimized using walk-test data, as well as the performance measure counters in each small cell. This data was collected and processed by Bell Labs innovation tools that can analyze and diagnose small and macro cells simultaneously. These automated and cloud-based tools made the process of network optimization faster and easier.
3. Power settings that address frequency overlap
Small and macro cells must overlap to some extent to allow users to continue wireless communication as they move in and out of an enterprise building. But this large enterprise small cell deployment had a frequency channel overlap in the small cell frequency band. This condition, known as a “raster carrier overlap,” is specific to some wireless service providers.
To minimize interference, the network design experts leveraged a site survey report, which helped them identify indoor locations with macro penetration. Then they set small cell power to override the macro signal, according to design guidelines.
These setting were then optimized using the Bell Labs innovation tool shown in Figure 1. The tool processes walk test data to speed and simplify analysis of RF metrics. In this case, it shows RF coverage on a single floor of one finance center building. Good signals are indicated by dark and light green.
Figure 1. RF coverage displayed on Bell Labs tool
Do these insights really make a difference?
The exceptional performance delivered by this 25-cell solution shows that they do. The large enterprise small cell deployment delivered significant improvements, as a result of Alcatel-Lucent expertise and methods — and Bell Labs tools that simplify small cell network optimization.
Our authors look forward to your questions and comments.