January 31, 2013, 11:20 AM — ZTE and China Mobile have successfully tested carrier aggregation, and achieved peak download speed of 223Mbps in the Chinese operator's LTE TDD network.
Carrier aggregation is one of the technologies that will be used to increase bandwidth in next-generation LTE-Advanced networks. It speeds up networks by combining two or more carriers into one channel in the same or different frequency bands.
The ZTE and China Mobile test, which was conducted outdoors, used two carriers of 20MHz each that were aggregated to 40MHz of spectrum to achieve the aforementioned 223Mbps.
LTE-TDD (Time-Division Duplex) or TD-LTE uses one channel for both upload and download traffic, compared to LTE FDD (Frequency-Division Duplex), which uses separate channels for download and upload traffic.
With LTE-TDD, operators can decide how much spectrum they want to allocate to upload and download traffic. ZTE and China Mobile decided to use 75 percent for the downlink and 25 percent for the uplink in its test.
As of early January, 13 commercial LTE TDD networks have been launched in countries such as Australia, Brazil, India, Russia and the U.K. That compares to over 10 times as many networks based on the FDD version on LTE, according to industry organization GSA (Global mobile Suppliers Association).
Three in Sweden and Aero2 in Poland use both versions in their networks. That is also what U.S. operator Sprint would be able to do if its acquisition of Clearwire is approved.
ZTE expects that the first LTE-Advanced networks will go live sometime during 2014, according to Magnus Isaksson, ZTE CTO in the Nordic countries.
"Our belief is that in general it is the handsets or modems that set the limitations for the first live network," Isaksson said via email.
The 223Mbps matches a demo Ericsson presented in November last year using commercially available equipment. ZTE said its test was the world's first to be completed in a "commercial environment."
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