A Paper by IBM Research on the Design and Implementation of the 28GHz Phased Array Antenna Modules in COSMOS will Appear in IEEE IMS’21

In a paper that will appear in IEEE IMS’21, a team from the IBM T. J. Watson Research Center at Yorktown Heights reports on the development of a compact and highly programmable 28-GHz phased array subsystem that is currently being integrated in the city-scale COSMOS testbed for advanced wireless research and experimentation. The subsystem hardware consists of a 28-GHz 64-element state-of-the-art dual-polarized phased array antenna module (PAAM), low-noise DC-DC power regulators with a single 12-V input, current sensors and an ADC for real-time supply monitoring, a phased-locked loop (PLL) for local oscillator LO (5 GHz) generation, intermediate frequency (IF) (3 GHz)/LO splitters, IF/LO baluns, and programmable switches. All of these components are integrated in a compact (10” x 5.75”) printed circuit board (PCB), which also supports the direct plug-in of a commercial-off-the-shelf FPGA system-on-module (SoM). The IF switches and splitters couple the PAAM to 20 IF ports that enable a rich set of multiple-input multiple-output MIMO configurations, including up to 8 simultaneous 16-element independent beams in each TX/RX mode. The FPGA and associated software enable the configuration of all subsystem features from a high-level application program interface (API), facilitating MIMO millimeter-wave wireless experiments. 28-GHz channel sounding measurements using the phased array subsystem coupled with software-defined radios (SDRs) is presented as a testbed-level experiment example, as shown Figure 1.

A 28-GHz SISO channel sounding demonstration: (a) two PAAM boards integrated with USRP N310 SDRs and compute servers; (b) pilot and data I/Q waveforms with fast beam switching capability.
Figure 1. A 28-GHz SISO channel sounding demonstration: (a) two PAAM boards integrated with USRP N310 SDRs and compute servers; (b) pilot and data I/Q waveforms with fast beam switching capability.

The detailed design and implementation of the 28-GHz phased array subsystem, and its integration in the COSMOS testbed were reported in a paper to appear in the IEEE MTT-S International Microwave Symposium (IMS’21):

  • X. Gu, A. Paidimarri, B. Sadhu, C. Baks, S. Lukashov, M. Yeck, Y. Kwark, T. Chen, G. Zussman, I. Seskar, and A. Valdes-Garcia, “Development of a Compact 28-GHz Software-Defined Phased Array for a City-Scale Wireless Research Testbed,” in Proc. IEEE International Microwave Symposium (IMS’21) (to appear), 2021. [download]