Carrier Aggregation study finds download peaks in excess of 100Mbps

A recent benchmark test carried out by consultancy Signals Research yielded some impressive results for LTE-Advanced technology carrier aggregation, allowing South Korean operators to deliver consistent peaks in excess of 100Mbps and average downlink speeds of 62Mbps.

South Korea is one of the most advanced telecoms markets in the world, with all three leading carriers already running LTE-Advanced networks. An announcement last week from Nokia Solutions and Networks confirmed that all three major operators, SK Telecom, LG U+ and Korea Telecom, have launched carrier aggregation technology, while the Signals Research findings show strong promise for carriers hoping to rollout the functionality in the future.

Carrier Aggregation is perhaps the first unique feature of LTE Advanced Release 10 that has been commercially deployed and will ultimately enable aggregated bandwidths of up to 100MHz. On a recent self-sponsored test drive in the Gangnam district of Seoul, Signals Research looked at the capabilities of the technology on an unnamed operator network in a 22km square area with a dense concentration of people and high-rise buildings.

Signals founder and CEO Mike Thelander said the advantage of Carrier Aggregation is that it allows an operator without 20MHz of contiguous spectrum to achieve a single 2x20MHz LTE channel with two 2x10MHz LTE carriers that are logically combined and deployed in different frequency bands. Another important advantage is that it lets an operator pair lower frequency bands with better propagation characteristics but inherently narrow blocks of spectrum with a mid-frequency band, giving operators the RF propagation characteristics of a sub 1GHz frequency band with the channel bandwidth of a 2.5GHz frequency band.

The consultancy purchased an LG G2 smartphone that supports Carrier Aggregation and an LG Optimus smartphone that is limited to LTE Release 8, as well as renting two LTE smartphones to take advantage of USIMs which offered unlimited daily usage. The company had access to a high bandwidth FTP server in the country although it augmented this server with a second FTP server located outside of the country and a UDP server located in North America.

The testing took place in the Gangnam district of Seoul from August 26 through August 29 between the hours of 0330 and 1900 and included a variety of applications such as VoLTE, video telephony, Skype Voice, Skype Video, 1080p video streaming, Google Play and web browsing. According to Signals Research the network in Seoul was definitely carrying a lot of LTE traffic as documented in the data usage figures that the operators report and the anecdotal evidence of subway cars and buses full of people and pedestrians walking down the street, all busy using their smartphones.

The company recorded an average downlink data rate of 62Mbps and a peak downlink data rate of 141Mbps during the testing, having transferred more than 100GB of data over a 3.5 day period.

Interestingly the peak data rate of 141Mbps was actually recorded at 09:14:17 in the morning, during rush hour and downlink data rates were in excess of 100 Mbps for 17.7 per cent of the time.

“We observed higher throughput in the early morning hours versus the period of the day when there could be the highest usage on the network, but even the latter results were highly compelling. Put another way, we documented throughput in excess of 100Mbps at all times of the day and night,” said Thelander.

Last week, SK Telecom said it has been granted access to 35MHz of bandwidth in the 1800MHz frequency range, which it will split 20MHz on the downlink and 15MHz on the uplink. Using carrier aggregation the company will upgrade its LTE-A download speeds to 150Mbps for all users of over 20 existing LTE devices including Vega Racer 2, Galaxy S3 and iPhone 5, without charging users any more.

The enhanced service using the wider spectrum channels will launch in the Seoul Metropolitan Area before the end of 2013 and should be extended nationwide by July 2014. But SKT is not planning to stop there. Using Carrier Aggregation technologies the company intends to combine its bandwidth allocation in the 1800MHz band where it has 20MHz bandwidth and the 800MHz band where it has 10MHz to offer downlink speeds of up to 225Mbps by next year.