6G Distributed MIMO Testbed for FR3

Sammanfattning

Research into distributed multiple-input multiple-output (D-MIMO) systems has gained increasing attention as a candidate technology for future 6G networks. However, evaluating such systems under realistic implementation constraints requires real-time testbeds that can capture effects such as synchronization, processing latency, hardware resource usage, and radio-frequency impairments. This thesis further develops the Lund University Large Intelligent Surface (LuLIS) testbed. The testbed is a scalable, field programmable gate array (FPGA) based testbed with 16 distributed nodes. The work consists of two main contributions. First, a new distributed digital baseband architecture is developed to increase the supported uplink processing capability from four to 32 users. The architecture supports a distributed part of maximum-ratio combining (MRC) and zero-forcing (ZF) detection schemes. Second, a front-end design for operation in Frequency Range 3 (FR3). The implemented digital baseband is evaluated in terms of functionality, latency, and FPGA resource utilization, while the analog front-end is characterized through measurements on an evaluation front-end. The results show that the baseband design is functional but that the implementation should be improved in a few ways, to reduce the use of BlockRAM resources on the FPGAs, and to reduce the latency in certain configurations. The evaluation front-end demonstrated performance similar to the theoretical estimates. The 16 channel front-end featured an improved design based on further research and learnings from the evaluation front-end but was not manufactured due to time constraints and potential for further improvement. Together, these contributions extend the LuLIS testbed toward larger-scale multi-user experiments and future upper-mid-band 6G research.