O2 Telefónica achieves carrier aggregation breakthrough

The carrier aggregation trial was supported by Nokia and MediaTek

At O₂ Telefónica’s Innovation Cluster near Berlin, the carrier has successfully aggregated sub-6 GHz spectrum frequencies in a two-component carrier uplink Carrier Aggregation (CA) trial on 5G Standalone. The trial, which was supported by Nokia and MediaTek, is reportedly the first of its kind and achieved a peak throughput of 144 Mbps using the combination of a 20 megahertz carrier on the 1800 MHz band (n3) and a 70 megahertz carrier on the 3.6 GHz band (n78).

Nokia provided solutions from across its AirScale portfolio including baseband, massive MIMO and RRH products, while MediaTek 5G Release-16 M80 modem integrated into the MediaTek Dimensity 9000 flagship chipset.

“We want to offer our customers an optimal 5G experience in their everyday digital lives,” said Mallik Rao, CTIO at O₂ Telefónica. “With frequency bundling, we will enable our customers to enjoy faster downloads and uploads in our 5G network in the future. Together with our long-time partner Nokia, we have succeeded in taking this step also for uploads in the 5G standalone network. Carrier aggregation will take our 5G network to the next level and improve the network experience.” 

CA allows mobile operators to use multiple sub-6 GHz spectrum channels simultaneously, as a method of increasing the bandwidth and speeds of their 5G networks. In this trial, the companies aggregated bands with different spectrum use techniques — the 1800 MHz band (n3) makes use of Frequency Division Duplex (FDD) mode, while the 3.6 GHz band (n78) uses Time Division Duplex (TDD) mode.

FDD uses separate frequencies for the uplink and the downlink and TDD uses a single frequency for both uplink and downlink, and therefore, they transmit at different times, making it more suitable when paired spectrum is not available. In general, FDD is considered better for coverage, while TDD is better for capacity.

FDD/TDD aggregation provides further network performance enhancements because it creates a sort of goldilocks situation, in which the high-band TDD coverage area can be improved by combining TDD with low-band FDD spectrum, and the TDD spectrum can significantly improve the overall downlink throughput.

“Uplink Carrier Aggregation of FDD and TDD combines frequencies to provide higher data rates and increased coverage, especially at the TDD cell edge and indoors,” Nokia explained in a press release. “This combination can greatly reduce the cost of network construction while improving network coverage and the user experience as well as helping ensure low latency.”