Could Small Cell Become a Pioneer of Open RAN Initiative?

By Guang Yang

Director, Strategy Analytics

In October, China Mobile quietly launched a tender for white box indoor small cell reference design. Two Chinese startup companies, BaiCells and BravoCom, won the project. This is only a small project for China Mobile, considering its huge network scale, but may be a ‘Great Leap’ for Open RAN (O-RAN) Alliance initiative. It indicates that China Mobile – who owns the largest number of cellular base stations worldwide – is firmly moving toward the objective of Open RAN.

In parallel Intel is currently testing a new 5G FlexRAN design with Chinese operators and vendor partners. China Mobile is active in the test, and is expected to join Vodafone and Telefonica soon to participate in an Open RAN trial. This could be a significant boost for the development of Open RAN and particularly the white box base station market.

Unlike most of Open RAN discussions, China Mobile’s white box small cell reference design specifically targets indoor scenarios. Around 70% of mobile data traffic is generated indoors today. The arrival of 4K/8K video streaming, Virtual Reality/Augmented Reality (VR/AR) and immersive media will strengthen demand for indoor coverage. Meanwhile, operators have to make indoor solutions extremely cost-effective to keep their business sustainable in this flat rate environment.

The white box small cell reference design could also significantly lower the entry threshold for new entrants into the equipment market. That’s why China Mobile is keen on the solution. China Mobile hopes to leverage new entrants to stimulate competition between vendors and eventually lower the deployment cost.

For new entrants a small cell white box built to a standard reference design lowers the barrier of creating a new baseband unit from scratch. But the base station still requires specific RF hardware including RF frontend, High Power Amplifier (HPA), etc. Macro cells usually require ultra-high transmission power i.e. 100 or 200 Watts for a 5G NR macro base station. The HPA is expensive and technically challenging. In fact the HPA and related RF front end have always created a high barrier for new entrants seeking to enter the mobile infrastructure market. However, small cells do not require such HPA. The transmission power of a 5G small cell is usually 2 to 5 Watts. In indoor deployment, the transmission power for 5G small cell is 100- 250 milliwatts. The power amplifier and RF is no longer a technical barrier. The lower transmission power RF and white box baseband create a combination that allows new entrants into the market.

In the coming 5G era, mobile networks will be increasingly densified and operators will have strong demand for cost effective small cell solutions. Meanwhile, small cells are a good starting point for the white box base station. O-RAN based small cell solutions are likely to play a disruptive role in 5G networks as they are adopted by the Open.