MTN LTE pilot: all the details

MTN recently took the wraps off their LTE (Long Term Evolution) trial network in Gauteng, comprising 100 sites in 4 coverage clusters in Johannesburg, Midrand and Pretoria.

LTE is widely seen as the successor to 3G technologies such as HSPA and evolved HSPA, and the forerunner to what the ITU considers 4G: LTE Advanced and WirelessMAN-Advanced.

Officially unveiling the project at an event at their headquarters in Johannesburg, MTN South Africa CTO Kanagaratnam Lambotharan explained that they will be testing the network with USB modems capable of downlink speeds up to 100 megabits per second (Mbps).

These category 3 modems from Huawei are also capable of uplink speeds up to 50 Mbps.

Kanagaratnam Lambotharan

Technical details

MTN revealed that the network was built in partnership with Huawei and Ericsson, using MTN’s own fibre infrastructure to link the sites to their core network. All their LTE sites use fibre optic cables for back-haul, Lambotharan said.

Lambotharan explained that the network was rolled out on 1,800 MHz spectrum they re-farmed from their allocation which was previously used for their voice network.

MTN achieved peak throughputs of 70 Mbps using 10 MHz wide channels in a 2×2 MIMO configuration. According to Lambotharan, the speeds could be even higher if wider channels were used.

He explained that they chose to use a smaller channel bandwidth in order to cover a much larger area without having to re-farm more of their voice network spectrum.

Lambotharan previously indicated to MyBroadband that they would like to make use of spectrum in the 2.6 GHz band, but the problem plaguing the allocation of the frequencies in the band have been numerous.

There will be a trade-off to going to the higher frequency, however. Lambotharan said that on 1,800 MHz the average coverage per site is 600 meters. With 2,100 MHz sites, the average coverage will be half that or less, he explained.

MTN LTE coverage map

Not open to the public

Though the network covers a fair portion of the most populous areas of Gauteng, MTN said that they will be cherry picking the testers for their LTE network.

They explained that they would prefer to select testers based on where they live and work while still ensuring they reach a critical scale in order to test the network’s robustness.

The trial is expected to run indefinitely, eventually transforming into a commercial offering, MTN said.

According to MTN, they expect to be able to launch LTE commercially in 2-3 years, though this timeframe is linked to spectrum being made available by ICASA

Two frequency bands are particularly attractive for LTE, namely the 2.6GHz (or 2,600 MHz) band and the 800 MHz band. The availability of the 800 MHz spectrum is linked to South Africa’s digital terrestrial TV (DTT) migration being completed, while the 2.6GHz band requires Sentech’s significant 50 MHz allocation in the band to taken back or migrated.

First round of testing

To showcase the benefits of LTE, MTN set up stations streaming YouTube videos, playing games and doing Speedtest.net bandwidth tests.

An initial round of testing showed the LTE network achieving download speeds over 50 Mbps to MyBroadband’s local Speedtest server, with upload speeds over 15 Mbps.

Internationally the LTE connection reached over 12 Mbps down and over 5 Mbps up.

One of MTN’s technical staff at the event in Johannesburg remarked that they saw much higher speeds on Speedtest.net servers listed on Speedtest’s actual site. This is strange considering that MyBroadband’s local Speedtest.net server is hosted in the MTN Business data centre.

YouTube videos, even more esoteric ones unlikely to be in the local Google caching servers, buffered extremely fast, allowing even 720p streams to play without waiting for them to load first.

Some of MTN’s staff also played a round of Counter-Strike to show off the low latencies of LTE, and the pings stayed well below the acceptable maximum for online FPS (first person shooter) gaming.

To test how well LTE performed when gaming on international servers, MyBroadband and MTN staff played a quick game of StarCraft 2 via Battle.net. There was no perceptible lag when issuing commands and downloading the content needed to load a map was fast.

It is still too early to call LTE the future alternative to ADSL for online gaming, but it will certainly be interesting to keep track of how LTE networks perform, in terms of both latency and speed, as they cope with greater demand.