Method and apparatus for transmitting reference signal in multi-antenna system

A method performed by a user equipment (UE) operating in a wireless communication system, the method comprising:

• receiving cell-specific reference signals (RSs) transmitted from a base station on two or fewer antenna ports in a downlink subframe including a first slot and a second slot and having a normal cyclic prefix (CP), wherein the downlink subframe has 14 orthogonal frequency division multiplexing (OFDM) symbols, and each of the first slot and the second slot has 7 OFDM symbols that are indexed starting from 0 in each slot;
• and
• receiving channel measurement RSs transmitted from the base station on eight or fewer antenna ports in the downlink subframe,
• wherein, based on the downlink subframe having the normal CP, the channel measurement RSs are mapped to the downlink subframe according to a predetermined pattern in which the channel measurement RSs are mapped to only two OFDM symbols in the downlink subframe,
• wherein for each antenna port which is used for a channel measurement RS that is mapped to one of the two OFDM symbols, the each antenna port is also used for a channel measurement RS that is mapped to another of the two OFDM symbols,
• wherein the two OFDM symbols are at OFDM symbol indices 1 and 3 of the second slot in the downlink subframe, and
• wherein the channel measurement RSs on the eight or fewer antenna ports are not mapped to any OFDM symbols in the first slot in the downlink subframe.

A base station configured to operate in a wireless communication system, the base station comprising:

• at least one transmitter and at least one receiver;
• at least one processor;
• and
• at least one memory storing instructions that, based on being executed by the at least one processor, perform operations comprising:
• transmitting, via the at least one transmitter, cell-specific reference signals (RSs) on two or fewer antenna ports in a downlink subframe including a first slot and a second slot and having a normal cyclic prefix (CP), wherein the downlink subframe has 14 orthogonal frequency division multiplexing (OFDM) symbols, and each of the first slot and the second slot has 7 OFDM symbols that are indexed starting from 0 in each slot;
• and
• transmitting, via the at least one transmitter, channel measurement RSs on eight or fewer antenna ports in the downlink subframe,
• wherein, based on the downlink subframe having the normal CP, the channel measurement RSs are mapped to the downlink subframe according to a predetermined pattern in which the channel measurement RSs are mapped to only two OFDM symbols in the downlink subframe,
• wherein for each antenna port which is used for a channel measurement RS that is mapped to one of the two OFDM symbols, the each antenna port is also used for a channel measurement RS that is mapped to another of the two OFDM symbols,
• wherein the two OFDM symbols are at OFDM symbol indices 1 and 3 of the second slot in the downlink subframe, and
• wherein the channel measurement RSs on the eight or fewer antenna ports are not mapped to any OFDM symbols in the first slot in the downlink subframe.

A user equipment (UE) configured to operate in a wireless communication system, the UE comprising:

• at least one transmitter and at least one receiver;
• at least one processor;
• and
• at least one memory storing instructions that, based on being executed by the at least one processor, perform operations comprising:
• receiving, via the at least one receiver, cell-specific reference signals (RSs) transmitted from a base station on two or fewer antenna ports in a downlink subframe including a first slot and a second slot and having a normal cyclic prefix (CP), wherein the downlink subframe has 14 orthogonal frequency division multiplexing (OFDM) symbols, and each of the first slot and the second slot has 7 OFDM symbols that are indexed starting from 0 in each slot;
• and
• receiving, via the at least one receiver, channel measurement RSs transmitted from the base station on eight or fewer antenna ports in the downlink subframe,
• wherein, based on the downlink subframe having the normal CP, the channel measurement RSs are mapped to the downlink subframe according to a predetermined pattern in which the channel measurement RSs are mapped to only two OFDM symbols in the downlink subframe,
• wherein for each antenna port which is used for a channel measurement RS that is mapped to one of the two OFDM symbols, the each antenna port is also used for a channel measurement RS that is mapped to another of the two OFDM symbols,
• wherein the two OFDM symbols are at OFDM symbol indices 1 and 3 of the second slot in the downlink subframe, and
• wherein the channel measurement RSs on the eight or fewer antenna ports are not mapped to any OFDM symbols in the first slot in the downlink subframe.