A key feature of the COSMOS platform is the integration of fully-programmable, high-performance SDR nodes with mmWave phased arrays. While there has been significant industrial and academic research on silicon-based mmWave phased array RFICs dating back to 2004, it is only recently that we are seeing commercial-grade mmWave phased arrays suitable for deployment in testbeds. Leveraging our ongoing partnership with IBM, the COSMOS platform will include mmWave nodes operating at both 28 and 60 GHz. The IBM 28GHz phased-array antenna module (PAAM) features 4 tiled RFICs supporting 64 dual-polarized antennas, 8 beams enabling hybrid analog-digital beamforming and MIMO, 30 degrees steerable beamwidth, 43 dBm EIRP, and up to 3 GHz IF. Another key aspect of the IBM 28GHz PAAM is the orthogonal amplitude and phase control enabled by (i) a gain-invariant phase-shifter design and phase-invariant variable-gain amplifier, and (ii) a careful antenna-array-in-package design the eliminates gain and phase mismatches. The front-end will offer rich programmability, including full access to the beamforming control, and latency as low as 10s of ns for low latency MAC and hybrid beamforming.