MIMO Terminal Performance Evaluation with a Novel Wireless Cable Method

Conventional conductive method, where antennas
on the device under test (DUT) are disconnected from antenna
ports and replaced with radio frequency (RF) coaxial cables, has
been dominantly utilized in industry to evaluate multiple-input
multiple-output (MIMO) capable terminals. However, direct RF
cable connection introduces many practical problems and a
radiated method to replace cable connection is highly desirable.
Existing wireless cable method relies on the knowledge of a
transfer matrix between the channel emulator (CE) output ports
and DUT antenna ports, and also requires an anechoic chamber,
which might be impractical and expensive. In this paper, a novel
wireless cable method is proposed and experimentally validated.
By recording the average power (i.e. reference signal received
power (RSRP) in the LTE) per DUT antenna port and selecting
optimal complex weights at the channel emulator output ports, a
wireless cable connection can be achieved. The proposed method
can be executed in a small RF shielded anechoic box, and offers
low system cost, high measurement reliability and repeatability.