Is Open RAN evolving for in-building use?

KF Hiew

02 September 2020

Since the formation of Telecom Infra Project (TIP) in the year 2016, Open RAN has always been one of the topics people are discussing in the workshop, seminar or conference of the industry. However, it doesn’t really catch big attention until the year 2018 whereby a couple of milestones were captured, Vodafone and Telefonica issued an RFI to assess the vendor capability, in addition, ORAN Alliance was formed to combine and extend the efforts of C-RAN Alliance and xRAN Forum into a single operator led effort. 


With the continuous efforts of worldwide ecosystem players, today we have moved one step further into the transition from “Why Open RAN” to “How and where to deploy Open RAN”. From the operator’s point of view, how to maximize the benefit and savings will remain the key focus and driver to introduce Open RAN. Specifically, for incumbent operators, it is believed that Open RAN will be introduced to serve either or both the following objectives. 

  • Extend 3G/4G rural coverage at the low cost 
  • Deploy the 5G network to introduce new services and capture new vertical market 


5G indoor connectivity is required to address vertical market’s requirements and Open RAN can reduce the cost 

Saturation of the consumer market and declining APRU have been a headache for the operators. In the long run, generating a new revenue stream is critical to surviving in a highly competitive market. 5G network connectivity is required to enable new services offering to the vertical industry and a lot of use cases will actually happen at indoor, AR/VR, industrial automation, telesurgery, just to mention a few. 


However, Indoor infrastructure is always a big investment for the operator even for sharing deployment given that more equipment or antennas are required to support the higher frequency band say n78 3.5GHz indoor coverage. Hence, the Open RAN solution will be the viable option to become the cornerstone of the 5G indoor network infrastructure. 


As shown in the diagram below, the overall architecture will be streamlined by having a gateway sitting in between Base station BBU and indoor infrastructure and removing the need for Radio RRU/RRH and passive components like POI/combiner etc. The immediate benefit we could expect is lower power consumption, lesser equipment space and no RRU/RRH overhead, eventually reducing both CAPEX and OPEX for 5G indoor deployment. The total savings will be huge taking into account that there are many venues which require dedicated infrastructure to connect indoor 5G users. 



Diagram 1: Inbuilding Open RAN architecture to enable CAPEX and OPEX saving


Open and centralized RAN could enable resource sharing between Macro and Indoor sites 

Most of the cell site traffic loading is changing all the time across the day, while some hours it spikes up and remains low for other hours. The trend for the inbuilding cell and macro cell may be very different, for instance, indoor traffic can be relatively high during lunch hour. Hence cell resource sharing can optimize the cell resource utilization in order to reduce capacity investment. 


For urban scenarios, thanks to the large availability of fiber networks, centralized RAN deployment will be possible to meet the required fronthaul bandwidth and latency. For instance, having the CU/DU located at the edge location connecting multiple macro and indoor cells as shown in the figure below, resource utilization can be maximized to reduce the CAPEX. 

Diagram 2: Open RAN and Virtualization enabling resource pooling


Undoubtedly, Open RAN will not only bring innovation and benefit to the Macro network but also indoor network deployment. However, how soon we shall expect the commercial deployment will be determined by other factors technically and commercially.

About KF Hiew

KF Hiew is a telecom professional with more than 10 years of experience, particularly focus on RAN and wireless networks. He is currently the Senior RF & Solutions Manager, Network Solution of Comba Telecom, responsible to manage and support regional large scale in-building network design and technical marketing activity.

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