TD-LTE to carry over 50% of traffic on Softbank’s network by 2018

By Tony Chan

The evolution of TD-LTE is positioning it as an ideal platform to offload data traffic from traditional FD-based LTE networks, according to Softbank.

According to technology planning division senior director Hidebumi Kitahara, the operator is looking at TD-LTE as the solution to supplement increasingly saturated LTE networks, expecting more than half of its traffic to be carried by TD-LTE by as early as 2018.

“Softbank has achieved almost 100% coverage nationwide with LTE. The next stage is to build more capacity to support demand,” Kitahara said at ZTE’s annual media and analyst conference in Shanghai. “We see TD-LTE as the solution for capacity on the 2.5GHz and 3.5GHz bands.”

Hidebumi Kitahara

However, even with the additional spectrum resources (70MHz of frequency in total) for TD-LTE, Softbank is facing capacity constraints with its network in its current form, partly due to the high user density of Japan; Kitahara pointed out that a whopping 80% of the traffic in Japan comes from the five biggest cities of Tokyo, Osaka, Kyoto, Sapporo, and Fukuoka, while overall traffic in Japan has surged 1,200x over the past 9 years. At the same time, physical space for mobile sites is increasingly at a premium.

“Every rooftop is occupied,” he said. “In metropolitan Tokyo, we have used up all available sites, so we need to increase the value each single site.”

Accordingly, Softbank is working on next-generation technology such as more advanced antenna systems. According to Kitahara, the operator is in the process of migrating its 4T4R multiple in, multiple out antenna system to 8T8R, which will yield a capacity boost of 1.8x. By the end of this year, Softbank aims to conduct trials of next generation ‘massive MIMO’ antennas from vendors including ZTE.

Enhancements of this kind on the TD-LTE network will expand its capabilities to support more traffic. According to Kitahara’s estimates, traffic on the TD-LTE portion of Softbank’s network will account for more than half of overall data traffic on the network by 2018 – a remarkable claim considering that Softbank has only 70MHz of TD-LTE spectrum compared to a minimum of 2x70MHz of paired frequencies on the 700MHz (2x10MHz), 900MHz (2x5MHz+2x10MHz), 1500MHz(2x10MHz), 1700MHz (2x15MHz), and 2100MHz (2x20MHz) bands.

To date, Softbank has a total of 40 million users, 10 million of whom are using the TD-LTE network. Usage patterns on the TD-LTE network, however, already support Kitahara’s projections. According to Kitahara, TD-LTE users are consuming 20x as much traffic as the typically smartphone
user on the conventional LTE network.

(This article first appeared on CommsDay)