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 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 in the long-term evolution) per DUT antenna port and selecting optimal complex weights at the CE 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.