30 June 2017, Shanghai – Dr. Xiang Jiying, Chief Scientist at ZTE Corporation, said that 5G mobile networks have the potential of offering equivalent or even better signal coverage than 4G LTE networks, as new technologies such as Space Division Multiple Access (SDMA) and beam forming emerge.

“As mobile operators prepare for 5G services, network coverage is the top challenge,” Dr. Xiang said in a presentation at the Network Evolution Summit during Mobile World Congress Shanghai 2017. “ZTE believes that lower-frequency 5G NR (New Radio) can absolutely achieve equivalent or better network coverage than 4G due to the link gain generated by new technologies such as SDMA, beam forming, and terminal dual-transmission channel precoding.

Compared with 4G LTE networks, which are mostly deployed in frequency bands below 2.6GHz, the higher frequency spectrum designated for 5G networks entail larger spectral signal path loss, making it more theoretically challenging to provide high-quality signal coverage.

Dr. Xiang said: “Especially in densely-populated urban areas, whether in Non-Line-Of-Sight (NLOS) propagation scenarios or Line-Of-Sight (LOS) propagation scenarios, the coverage of 3.5 GHz 5G NR is superior to that of 2.6 GHz FDD LTE, and therefore the co-location of 5G and 4G is completely feasible.”

The ability to co-locate base stations will help operators to reduce the 5G site quantity, save the initial 5G investment and increase returns of investment in 5G networks, with more continuity in the deployment roadmap, Dr Xiang said.

Among core 5G technologies, the key to improving the spectrum efficiency with the air interface is SDMA, Dr. Xiang said. SDMA can increase the system capacity several times without additional frequencies, and time and space resources, and is an important means to improve the network capacity and resolve the shortage of spectrum resources of operators.

In 2014, ZTE took the lead in deploying SDMA technology in both the future 5G networks and the existing 4G networks, significantly improving data rates. ZTE’s proprietary Pre5G solutions help operators to fast-track the application of 5G technologies on existing 4G LTE networks.

ZTE’s Pre5G Massive MIMO solution is deployed by internationally-leading operators including SoftBank and China Mobile. ZTE’s industry-leading capabilities in SDMA make the company well-positioned in the 5G era, and the valuable experience of commercial 4G SDMA networks lays a solid foundation for the commercial use of 5G SDMA and accelerates the development and commercial use of 5G networks.

Dr Xiang said operators will need to address the issue of re-segmentation of 4G access network architecture to manage the costs of deploying 5G networks.

“If the 4G CPRI interface mechanism is still used in 5G networks, the interface bandwidth is too high, resulting in the extremely high cost of 5G bearer networks,” Dr Xiang said. “Therefore, the re-segmentation of the 5G access network architecture becomes inevitable. So far, seven solutions have been proposed for the segmentation of 5G access networks. If the segmentation points are closer to the RF processing layer, the requirements for the transmission bandwidth and delay are higher and the system performance is better. If the segmentation points are closer to the user plane processing layer, the requirements for the transmission bandwidth and delay are lower while the radio performance loss is higher accordingly.”

ZTE believes that the selection of the segmentation points must give proper consideration to both the acceptable cost of bearer networks and the performance of radio systems. ZTE prefers the well-balanced solutions with moderate requirements for bandwidth and delay and with good radio performance, which helps the convergence of 4G and 5G networks.

In addition, in view of the diversity of 5G services and the difference of application requirements from different industry verticals, a 5G network must be able to achieve flexible combination of network functions and the on-demand deployment of network elements, Dr Xiang said.

“In the future, 5G network functions will be completely distributed in the virtual access networks on demand. 5G bearers must use the innovative xHaul solution that integrates the IP and optical transmission technologies to include multiple interfaces, such as the Ethernet, CPRI, and eCPRI interface, in the same underlying optical fiber network, support flexible end-to-end logical slicing of 5G networks, and fully satisfy the bandwidth and delay requirements for the eMBB, mMTC, and uRLLC services.”

As the first 5G standards are released in 2017 and 2018, ZTE is increasing its investment on 5G research and development to consolidate the company’s leading position in next-generation networks, and is aiming to be among the first vendors to offer 5G-compliant solutions to give customers the first-mover advantage.