China Telecom and Nokia Networks say they have demoed FDD-TDD carrier aggregation with a peak download speed of 260Mb/s using a commercial user chipset from Marvell.
The speed was achieved using 20MHz of (paired) FDD spectrum in the 1.8GHz band and 20MHz of (unpaired) TDD bandwidth in the 2.6GHz frequency. The FDD spectrum contributed 150Mb/s to the total speed while TDD spectrum contributed 110Mb/s.
The successful testing of interoperability of an LTE base station with a user device chipset is a step towards improving the LTE network speed and coverage for LTE users in areas where both variants (FDD/TDD) of LTE technology are deployed.
This will be important for China Telecom, since it will be able to use its FDD band 3 for improving LTE coverage and TDD band 41 for improving throughput and capacity.
Phil Marshall, chief research officer at Tolaga, told Mobile World Live that carrier aggregation between FDD and TDD is significant because it helps unlock TDD spectrum resources. “However, it does not imply that we can do carrier aggregation between FDD and TDD in any band. I think it is telling that the aggregation is between 1800 FDD and 2600 TDD carriers — I presume this is needed to reduce interference problems between the FDD and TDD systems (e.g. 2600 FDD and TDD collocation would be really hard).”
The first 4G licences approved by the Chinese government last December were for TD-LTE. It is expected that FDD-LTE licenses will be approved early next year. In June it was reported that China Unicom and China Telecom had already picked-up licences for trial FDD-LTE networks in 16 cities.
Nokia and China Telecom said in a statement the demo shows that FDD-TDD carrier aggregation is rapidly getting closer to commercial adoption.