Patent ID: 9008071
Filing Date: 2015-04-14
Classification: H04B,H04J,H04L,H04W

Abstract:
1. A method for transmitting downlink data to a user equipment (UE) in a wireless communication system, the method comprising: transmitting rank information for indicating a number of transmission layers for the downlink data to the UE; and transmitting demodulation reference signals (DMRSs) of the transmission layers for the downlink data for demodulation of the downlink data through a first code division multiplexing (CDM) group and a second (CDM) group to the UE, wherein the first CDM group is configured with a predetermined first time-frequency resource set and the second CDM group is configured with a predetermined second time-frequency resource separate from the first time-frequency resource set, wherein each of the DMRSs of the transmission layers for the downlink data is transmitted in the first CDM group or the second CDM group using one of predetermined orthogonal cover codes (OCCs) according to a predefined mapping rule, and wherein the predefined mapping rule defines a one-to-one correspondence between 8 DMRSs and 8 transmission layers, and maps each of 8 DMRSs for 8 transmission layers to the first and second CDM groups and to one of the predetermined OCCs.