Abstract: To solve the system performance degradation problem caused by the limited sounding reference signal (SRS) resources in time duplex division (TDD) massive multiple-input-multiple-output (MIMO) systems, based on the fact that the channel variant rates of various users are different, one metric that determines the sounding period is provided firstly, and then a pilot allocation scheme is given to expand the scheduling set, and finally a matched multiuser grouping scheme is introduced. Meanwhile, a 3-D MIMO channel model is used to verify the scheme. Simulations show that the system performance is effectively enhanced.

Key words: limited sounding reference signal resources, multi-user grouping, pilot allocation