China set for in-flight air-to-ground 5G launches

ZTE readies airlines for commercial take-off of 5G in-flight connectivity in China.

TMN has learnt that four Chinese airlines are close to announcing that they will deploy air-to-ground (ATG) 5G services for in-flight connectivity.

Liu Weiwei, General Manager of ATG Products at ZTE, told TMN that in 2021, two 5G ATG networks will be deployed, with more to follow.

“Our partner mobile operators have already discussed with several airline companies individually about installing airborne 5G ATG equipment to trigger high speed IFC (In Flight Connectivity),” he added.

Weiwei didn’t have details on how many routes would be covered, but he did say that “several major domestic airline routes” would have coverage in the first half of 2021.

“5G ATG will be deployed on several major domestic airline routes. How quickly it will cover the entire airspace over China will be determined later in accordance with the service and aviation requirements, ” he added.

The ZTE executive said all of China’s airspace could be covered with fewer than 1,000 base stations “with a deployment period of less than three months.” 

“Therefore final 5G ATG deployment plans will be driven by market factors,” he added. “Currently, the network deployment strategies are not finalised. It might be feasible to start from experimental routes then progress to national coverage but roll-out could also start with national deployment.”

Although there are no details as to how many planes will be equipped, Weiwei said, “Generally speaking, in future all single-aisle planes will be equipped with 5G ATG for domestic passengers, which accounts for a large majority of the total civil aircraft. In the meantime, as the private aircraft market increases, it becomes another source of potential customers for 5G ATG.”

Air-to-Ground 5G technology combines ground-based base stations with on-board active array antennas and CPE, alongside a WiFi access point. Satellite links are often part of the mix, providing redundancy or backhaul where the aircraft is outside of coverage. (ZTE said that single aisle aircraft will have only ATG in flight connectivity, but for wide-body aircraft  a combination of ATG and satellite communication will be the trend.)

Other companies exploring the commercial aviation sector include ex-Nokia spin-off Skyfive, which says it also has partners in China, and also Gogo in the USA, which is now owned by Intelsat

ZTE’s ATG solution supports 1,200 kph flight speeds with 300km coverage radius, so that users can obtain service  at a height of 10,000 meters. Massive MIMO capabilities mean each airplane exclusively occupies a beam with 100 MHz bandwidth, giving a maximum uplink/downlink throughput of 150Mbps/800Mbps. ZTE says that can support more than 160 passengers enjoying the 1080P HD video experience simultaneously.

ZTE says that its on-board CPE supports the N79 frequency band, weighs 7.5 kg, and has power consumption at normal temperature <150 W. It includes a 7nm chipset from ZTE.

Weiwei said, “The ground network includes dedicated ATG ground AAU and BBU, which are similar to 5G ground macro base stations, only with more protocols and customised product design for aviation scenarios.”

One aspect that ATG systems must overcome is the frequency Doppler effect created by communicating wireless signals to vehicles moving at high speeds. ZTE’s system uses frequency offset compensation technology in the 5G ATG base stations and airborne equipment to pre-compensate for uplink and downlink channels respectively.

Weiwei said that a specially designed frame structure combined with PRACH transmit timing adjustment and uplink/downlink HARQ technologies can realise up to 300km  cell coverage, “greatly reducing network rollout costs and ensuring system performance”.

“The airborne antennas can enhance signals and suppress interference, achieving 360-degree  network access in the air. By adopting Ground & Air Co-spectrum technology, telecom operators can use the spectrum they already have to build ATG networks,” he said. In China that means 4.9GHz (n79) will be the dominant ATG band.