Mobile networks did not crash: COAI chief

Jacob Cherian

MUMBAI IN THE hours following the seven bomb blasts last Tuesday, anyone in Mumbai or attempting to call the city can testify how difficult it was to reach someone on a mobile phone. The public and media were quick to accuse cellular networks for not rising to the occasion.

TV Ramachandran, the director general of Cellular Operator Association of India (COAI) defended the networks pointing out similar problems with the land lines as well. He said that it was impossible to have anticipated and be prepared for such an exponential rise in the demand to communicate.

Pointing out that some networks had logged 500% call-traffic during those crucial hours, he said, “If a network has to be prepared for a 500% call load, the cost to the customer would shoot up by five times.” A senior technical officer with Airtel observed that the load on their network clocked three times it’s maximum capacity. “As a dimensional rule we keep 50% extra capacity in case of an emergency,” he said.

But obviously with a 300-500% spike, 50% extra is not enough. He went on to explain that once the load crosses 200%, which is the threshold, an automated feature kicks in and begins to reject the excessive calls till the load comes down to a manageable level. There are a couple of options for such a crisis.

A technique that is employed by some and not all networks, is known as the ‘half-rate codec’. Simply put, it is when two calls are fit into the bandwidth of one call. To this, Mr Ramachandran said, “At a network crunch, to introduce the half-rate codec would mean a loss of quality.”

“What is more efficient is AMR (adaptive multi-rate), as it adapts itself to the signal is to noise ratio. However, most people would have to change their cell phones,” said the COAI, director general. He added that phones equipped with AMR are available in the Indian market. He went on to suggest that nothing can be more effective than repeated tries or text messaging. He dismissed allegations that networks crashed.

An expensive, but a far more effective option would be the deployment of a COW (cell on wheels) or a NOW (network on wheels). These can be deployed by a network to increase the number of transmission towers to their grid. The NOW is a transmission tower that is built onto the back of a truck.

Its size is not much larger than an ambulance. The NOWs are known to have been a saving grace after Hurricane Katrina washed over New Orleans. Major networks are equipped with NOWs, but these are usually engaged when a spike is anticipated, like festivals or political rallies.

“In case of Diwali or New Year’s Eve, we can deploy these networks on wheels,” an industry official explained. However, he added that it requires many weeks or even months of planning to decide which place would be the most efficacious. He indicated that New Delhi alone is equipped with 30 to 40 NOWs.

However, he refused to disclose how many were in Mumbai. Mr Ramachandran said that a NOW would cost the price of a truck plus approximately Rs 14 lakhs (the cost of a transmission tower, minus structural costs). This is not the first time that such a breakdown in communications has happened.

The Americans experienced it immediately after the World Trade Centre attack, the Britons when their Tube and double-deckers were bombed.

People from all over the world reached out to their loved ones living in the afflicted cities and overloaded the systems.