Lowering latency is key to several emerging mobile use cases including high quality mobile video and autonomous vehicles. Much of the work in this area is related to 5G, but SK Telecom and Nokia have made a breakthrough on an LTE network, reducing latency from current 4G levels around 25ms, to just 2ms.
The proposed specification for 5G calls for ultra-low latency of 1ms or less, though this is a challenge which many think will not be met until a future generation of the standard, except for very small packets (the smaller the packet, the lower the latency). However, getting to 2ms on a 4G network raises hopes that the 3GPP specs may not be over-optimistic after all.
They achieved this by applying uplink pre-scheduling, a technology that enables the device to transmit data to the base station immediately; plus short Transmission Time Interval (TTI), which reduces data transmission time between base station and handset.
“Low latency technology is essential in realizing 5G services such as autonomous driving, artificial intelligence and virtual reality services,” said Park Jin-hyo, head of the South Korean operator’s network technology R&D Center. “We will continue to improve our low latency technologies to achieve 5G evolution, while applying the latest technologies to our LTE networks to further enhance customer experience.”
SK Telecom used self-driving vehicles as its example, saying that, on an LTE network with 25ms latency, a car running at 150km per hour would travel about one meter after a stop signal was issued, before it began to decelerate. At 2ms latency, the figure is eight centimeters.