Build and basic documentation has been completed for the subsystems which will be used in the initial LibreCellular CI hardware configuration.

We’ve made good progress over the past couple of months and are pleased to report that the build has been completed for the initial CI platform subsystems, which will enable testing with:

• 1x Reference Hardware Platform base station
• 8x LTE modems
• SISO configuration

Over the course of time additional subsystems will be assembled to also enable testing of:

• 2×2 MIMO (via integration of a second CIRF4x16 RF network)
• VoLTE (via CIMODQ4 subsystem)
• Cost Optimised Base Station
• Multi-base station configurations

However, there is plenty to be done first in terms of software integration and developing the initial tests. Next let’s take a look at the subsystems assembled so far.

Subsystems

CIPSU internal view.

Hardware assembly has been completed of the following custom subsystems:

• CICON. CI Controller based on PC Engines APU2E4 SBC + LibreCellular CONIO-A.
• CIRAN1. LimeSDR-USB + Intel NUC base station.
• CIRF4x16. 4:16 RF splitter/combiner network with digitally controlled RF attenuation.
• CIMODS8. 8X LTE modem bank.
• CICLKD. Reference clock distribution.
• CIPSU. 12VDC (50A) + 5VDC (21A) combined PSU and PDU.

In addition to which there are the COTS subsystems for RF test and measurement, CI host and Ethernet switch. For further details, see the CI Hardware Platform documentation, where a block diagram, theory of operation and bill of materials (BOM) can be found for each custom subsystem, along with links for 3D CAD models, manufacturing files and front/rear panel graphics.

Next steps

Subsystems have been “smoke tested” as assembly has been completed for each and so the next task is to cable between units, install the O/S and initial software on CIHOST, CICON and CIRAN1, then following which proceed with integration testing. The next CI milestone will be reached once we can run a simple automated test with one LTE modem connected to the base station.