  The upcoming 3GPP global mobile communication standard 6G strives to push the
technological limits of radio frequency (RF) communication even further than
its predecessors: Sum data rates beyond 100 Gbit/s, RF bandwidths above 1 GHz
per link, and sub-millisecond latency necessitate very high performance
development tools. We propose a new SDR firmware and software architecture
designed explicitly to meet these challenging requirements. It relies on
Ethernet and commercial off-the-shelf network and server components to maximize
flexibility and to reduce costs. We analyze state-of-the-art solutions (USRP
X440 and other RFSoC-based systems), derive architectural design goals, explain
resulting design decision in detail, and exemplify our architecture's
implementation on the XCZU48DR RFSoC. Finally, we validate its performance via
measurements and outline how the architecture surpasses the state-of-the-art
with respect to sustained RF recording, while maintaining high Ethernet
bandwidth efficiency. Building a 6G integrated sensing and communication (ISAC)
example, we demonstrate its real-time and rapid application development
capabilities.
