Driving diversification of mobile network architecture

Solutions to the RAN "Big Bang" and its continued expansion

The demand for diversified supply of radio access networks (RAN) is a hot topic in the communications industry. The shift to a more open distributed RAN architecture, with standardized, interoperable interfaces between network elements (such as the Small Cell Forum's nFAPI and the O-RAN Alliance's Open Fronthaul), can provide the best equipment selection for each network node. And this architectural approach is flexible enough in actual network deployment to cope with various challenges in real-world environments.

Over the past 40 years, the demands placed on radio access networks by cellular networks have grown dramatically, along with the resources available to meet those demands.

This RAN "Big Bang" began with the search for a wireless communication service (voice) and a cellular network (macro base stations) and the resulting radio environment challenges . As a result, a standard (TACS/NMT/AMPS) was created, a wireless network occupying a specific frequency (usually 900MHz) and channel bandwidth (e.g. 25kHz).

As a result, both the sources of demand and the solutions have grown at an extraordinary rate (or the "entropy" or disorder has increased). Driven by the number of users and the number of service types, the traffic demand and diversity required of the RAN has increased exponentially over time. To meet these challenges, mobile operators have used a dizzying array of frequency bands, designed five generations of increasingly complex cellular wireless communication standards to provide reliable service on channels of diverse bandwidths, and ultimately supported various combinations of these channels, frequency bands, and standards on different networks and in different countries.

Even with the new tools provided by standards evolution and the availability of new spectrum, the physical implementation of the RAN must be more tailored to the needs of the environment than in the early “big bang” stages to maximize coverage and capacity.

If you open the satellite imagery map app and zoom in on a dense urban center, you'll see a wide variety of buildings and environments. As you swipe north, south, east, or west, you'll find offices, malls, stadiums, parks, public transportation infrastructure, and more. As you zoom out, you'll see how these environments change between dense cities, urban areas, suburbs, and rural areas. You'll even see differences between the same types of environments.

This rich variety of scenarios requires a variety of RAN architecture options to match them in order to effectively address various challenges in terms of network cost, performance, and basic deployment capabilities. However, without optimized chips to meet the processing and transmission requirements of high-performance 5G NR networks and sufficient flexibility to meet various application scenarios, it is impossible to meet the cost and power consumption targets of the target network unit.

Small cells are at the forefront of addressing many capacity and coverage deployment challenges to place antennas in the most advantageous locations possible while leveraging available fronthaul and backhaul technologies to use those antennas most efficiently. The distributed architecture of the RAN allows small cell network architecture to be flexible enough to adjust to meet these diverse needs rather than forcing a one-size-fits-all approach.

Of course, in order for small base stations to play a role in this new operational model change, the infrastructure of small base stations must also change as needed. At present, some manufacturers on the market have launched high-performance FPGA+CPU small base station baseband solutions, which have verified that small base stations can play a big role, but the market still needs higher performance and lower power consumption. Therefore, integrating small base station baseband processing and even more functional modules into SoC is a more efficient and economical model, and is also the basis for more effectively supporting operators to achieve RAN architecture diversification.

Picocom launched the PC802 5G baseband SoC at the end of last year, which has been adopted by nearly 20 customers, four of whom have completed the design of small base station products and made calls. Judging from the definition and final implementation of these customers' 5G small base station products, their products have their own characteristics and strengths, and can meet the needs of operators in different market segments, further proving that small base stations are an important force in promoting the diversification of RAN architecture.