Fixing Call Drop Problems in Delhi, Mumbai Means Hundreds to Thousands of New Cell Sites

There seems to be one thing mobile service providers and the Telecom Regulatory Authority of India can agree on: more cell towers are needed. The good news probably is that problems are confined to a relatively small percentage of urban sites in Mumbai and Delhi, for example.

Depending on which performance indicator is used, the percentage of sites with call drop problems that exceeded three percent of calls, at any hour of a typical day, represent less than one percent to a maximum of two percent of sites.

The bad news is that fixing problems at those locations, in the near term, might have to rely heavily on redesigning the service areas by shrinking cell sizes.

Depending on how much cell radii have to shrink, the number of sites might have to grow by four to 16 times (assuming coverage areas get smaller by 50 percent or 75 percent).

Assuming locations can be obtained from landowners or building owners, that could still mean hundreds to several thousand new tower sites in cities such as Mumbai or Delhi, by each operator, unless the operators are able to share tower locations at a very significant level.

That is partly a business issue, but might also be dictated by the frequencies used by each of the operators and how they already have designed their networks. Those considerations will limit the spots where new towers can be added, and therefore could limit the degree of potential tower sharing.

Still, both TRAI and mobile operators agree new sites are required.

A new report on call drops in India, published by the Telecom Regulatory Authority of India, suggests that some mobile operator sites have no particular call drop issues, while others have significant problems, based on TRAI drive tests as well as analysis of performance records regularly submitted to TRAI by mobile operators.

Performance also varies based on the actual performance indicator examined.

TRAI’s study of call detail records from mobile operators in Delhi showed problems at six out of 8604 sites operated by one supplier;  10 out of 15850 for a second operator and 504 out of 16117 sites for a third operator.

In other words, the towers where call drop standards exceed TRAI standards (two percent or fewer dropped calls) are very few in number, compared to the total number of sites examined by TRAI.

Specifically, though for one operator about three percent of sites were problematic, two other mobile operators had problems with quality at just 0.06 percent or 0.07 percent of sites.

Weak signal strength, though not the only cause of call drops, is a big factor. Radio link failure also was found to be a big issue.

A different analysis based on cells with three percent call drop rates at any hour of the day showed one operator with 108 out of 8604 sites affected; a second operator with 106 out of 15850 sites exceeding the three-percent threshold; while a third operator had call drop issues of three percent or more at 335 sites out of 16117 locations.

In other words, cell locations that exceeded three percent call drops at any hour of a typical day represent less than one percent to a maximum of two percent of sites.

In a statement that mobile operators and TRAI can agree on, the report says “there is an urgent need to increase the number of the towers.” The full report also shows that blocked calls are an issue, not simply dropped calls.