Delivering a “White Box” Future for the Base-station

The cellular Radio Access Network (RAN) has evolved dramatically over the past 20 years. A wide range of macro and small cell solutions have been introduced into the market that can be deployed in a greenfield location, on the rooftop of a commercial building, as well as with low-profile, pole site-type solutions. Also, the number of RAN vendors has also evolved remarkably. From around 10 to 15 national and regional infrastructure vendors, the list has contracted to essentially 4 vendors: Ericsson, Huawei, Nokia, and ZTE.

The mobile operator community, however, is concerned about the level of competition in the wireless telco infrastructure marketplace. Mobile service providers are under considerable pressure to not only introduce new services to boost revenues but also cut Capital Expenditure (CAPEX) and Operating Expenditure (OPEX) to improve profit margins. By making the base station more of a “white box”, that is to say, more modular and inter-operable, the mobile operators behind the Open RAN (O-RAN) initiative believe they can stimulate competition and innovation between the incumbent four mobile telco vendors and encourage new vendors to enter into the marketplace.

The number of base stations now stands at 11.88 million and is anticipated to grow to 18.45 million by 2025, of which small cells will constitute 23% by the end of the forecast. While the net increase in base stations is 6.5 million compared to 2017, a considerable amount of upgrade and swap-outs will take place as enhancements in technology, smaller equipment form factors, and reduced power supply requirements materialize.

Mobile telcos are keen to make base station hardware more modular and interoperable between the vendors. Fundamentally the base station is made up of an “antenna”, a “radio,” and a “baseband unit.” While antennas can be purchased from multiple antenna vendors, such as Kathrein, Huawei, CommScope, and Amphenol, and from least 10 more vendors, the radio and the baseband units are typically all supplied by the Big Four. There have been efforts to standardize base station equipment. Common Public Radio Interface (CPRI) has had more traction in the market compared to the Open Base Station Architecture Initiative (OBSAI). However, the further modularization of the radio and baseband unit elements has been held up as the base station telemetry, fault alarms, housekeeping functions, etc., have still be been vendor specific. Mixing one vendor’s radio with another vendor’s baseband unit would lead to the base station simply being shut out of the network due to a lack of interoperable management interfaces between the respective hardware.

From ABI Research’s own research, the five-year Total Cost of Ownership (TCO) of a macro cell site can range from US$100,000 to US$200,000. Even for a small cell site, the TCO is still within the range of US$20,000 to US$50,000, depending on the deployment scenario and the geographic market it is in. There have been a number of initiatives to streamline the radio access network architecture:

Centralized RAN: Centralized RAN (C-RAN) strove to locate the operator’s baseband units in more centralized locations. Therefore, instead of the baseband unit siting on the pole or at the base of the tower, the baseband units are housed in a central office. This not only reduces the amount of equipment at the cell site but also allows Self Optimizing Network (SON) technology that can adjust the power of individual cell sites depending on real-time demand to be deployed.

Virtualized RAN: The concept of virtualized RAN (vRAN) in fact complements C-RAN. Proprietary baseband unit equipment is replaced with generic, server-based computing electronics, where the baseband function is performed in software in a centralized office. For more information on vRAN, see Nick Marshall’s Foresight article vRAN a Hot Topic at MWC18 (IN-5064).

Preparing for 5G

As much as Common Public Radio Interface (CPRI), C-RAN, and V-RAN have helped to streamline the base station, mobile telcos are keen to push the modularity and interoperability to the next level. In February 2018, a number of operators, including AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO, and Orange, formed the O-RAN Alliance, which “combine[s] and extend[s] the efforts of the C-RAN Alliance and the xRAN Forum into a single operator led effort.”

At Mobile World Congress Shanghai 2018, an additional seven operators, Bharti Airtel, China Telecom, KT, Singtel, SK Telecom, Telefónica, and Telstra, joined the O-RAN Alliance. They also announced the formation of seven study groups to ultimately achieve a “white box” approach to the deployment and management of a mobile network:

• WG1: Use Cases & Overall Architecture
• WG2: Radio Intelligent Controller (RIC) (non-Real Time) & A1 Interface
• WG3: RIC (near-Real Time) & E2 Interface
• WG4: Open Fronthaul (FH) Interface
• WG5: Stack Reference Design and F1/V1/E1/X2
• WG6: Cloudification and Orchestration
• WG7: White Box Hardware

It will not be plain sailing for the O-RAN Alliance. There are a few alternative initiatives to tackle the complexity of the mobile cellular base station. There is the xRAN Forum, Intel’s FlexRAN, and Telecom Infra Project’s (TIP) OpenRAN Project Group. Nonetheless, all four organizations are setting out objectives for rationalizing equipment and setting standards for interoperability of hardware and software. It is likely the mobile operators will dictate the fate of these alliances. As critical mass builds up for a particular group, it is likely the larger community will then likely sign up.

The challenges ahead of the O-RAN Alliance’s study groups should not be discounted. While many in the industry have argued that these proprietary, legacy architectures built into the base station radio and baseband unit equipment has helped to protect the commercial domains of incumbent infrastructure vendors, mobile telcos have also demanded the highest customization, performance and energy efficiency characteristics from the vendors. If enough mobile telcos declare their desire for base station equipment to be open sourced, the incumbent vendors, Ericsson, Huawei, Nokia, and ZTE, will have to heed them. It will be interesting to see if new “white box” infrastructure vendors move into the sector. Furthermore, some base station solutions could pose a very significant challenge, such as for active antennas where the radios have to be integrated into the antenna itself.