It seemed we were more or less resigned to Huawei owning 5G infrastructure worldwide. Then questions about security came to the fore, Huawei purchases were put on hold (though that position is being tested outside the US) and opportunity for other infrastructure suppliers (Ericsson, Nokia, etc) has opened up again.
Building 5G baseband systems (what goes in the cell tower and beyond the tower) is immensely complicated. The baseband divides into 3 units – remote radio units (RRUs) which connect directly to the antennae, a distributed unit (DU) which sits at the base of the tower, which in turn connects to a central unit (CU) to manage connections to multiple DUs.
Incidentally wireless technologies, particularly cellular, breed acronyms like rabbits. I’ll introduce a few here. For example, that thing from Apple or Samsung on which you make calls? It’s not a cellphone, it’s a UE (user equipment).
A 5G RRU needs to deal with sub-6GHz signals and above 6GHz, including millimeter wave. Wi-Fi (802.11ax) and legacy LTE are supported, so RRUs must support multiple radio access technologies (RATs – see what I mean?). The RRU should handle massive MIMO (multi-input, multi-output) reception and transmission, together with beamforming to optimize signal strength. Most of the rest of the processing is handled in the DU and CU.
The base station part of the network in principle sits in that box at the bottom of the cell tower, handling more advanced communication functions and connecting through backhaul to central stations which manage call routing. Except all that is changing. It turns out that having a lot of dedicated electronics for each tower is an expensive proposition for the network operators, especially if demand varies significantly through the day (as it does in metro areas for example).
That has driven variation in who does what, and where, in radio access networks (RANs – from the CU do the DUs to the RRUs). The first switch was to centralized RANs (C-RAN) where almost everything except the RRUs move to central offices. That’s now evolving to virtualized RANs (V-RAN) where there is more flexibility to move functions around. There’s even discussion on an open RAN standard (O-RAN).
Through these systems, the various flavors of 5G must be supported. There’s enhanced mobile broadband (eMBB), the high bandwidth version which will allow you to view 4K TV on your phone or enjoy mobile gaming, VR, MR, etc. Ultra-reliable low latency communication (URLLC) is what you need for safety-critical applications in your car or in medical functions – fast, low bandwidth but dependable latency. Other applications include machine to machine communication (MMC) and fixed wireless access (FWA).
Sailing briefly into acronym-free waters, all these flavors require a lot of multi-core and multi-thread support along with ability to aggregate and flexibly manage traffic from and to multiple targets. Like virtualized job management in data centers except that here you are dealing with high bandwidth communication, all of it requiring a pretty high QoS and some of it requiring guaranteed QoS. (Sorry – I promised no acronyms – QoS = quality of service)
Finally, the 5G standard continues to evolve. Release 15 just came out, release 16 is expected in a few months and release 17 is planned for next year. Anyone planning to hardwire 5G baseband is dead before they start. All of these solutions have to be software based (software defined radio – SDR).
CEVA has just released their XC16 DSP, a core designed specifically for baseband and designed in close partnership with a leading equipment vendor. They’ve also announced that Nokia and ZTE have adopted this platform. This is starting to look more like a horse race again. And meantime you’ve learned more cellular acronyms than you ever wanted to know.
You can learn more about the XC16 HERE.