# US 2018/0026764 A1 · Method of mapping transmission layers to frequency division multiplexed demodulation reference signal ports > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026764 A1 - Document ID: US20180026764A1 - Status: Published application - Kind: A1 - Application number: 15/272,783 - Filed: 2016-09-22 - Published: 2018-01-25 - Earliest claimed: 2016-07-25 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: June NAMGOONG; Jing JIANG; Alexandros MANOLAKOS; Krishna Kiran MUKKAVILLI; Joseph Binamira SORIAGA; Tingfang JI - Web page: https://patentgrep.com/patent/US20180026764A1 ## CPC - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04B 7/0413: MIMO systems - H04L 5/0098: {Signalling of the activation or deactivation of component carriers, subcarriers or frequency bands} - H04L 25/0204: {of multiple channels} - H04L 25/0224: {using sounding signals} - H04L 25/0256: {Channel estimation using minimum mean square error criteria} - H04L 5/0016: {Time-frequency-code} - H04L 5/0023: {Time-frequency-space} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION ## Abstract A method for mapping transmission layers to demodulation reference signal (DMRS) antenna ports may include: determining a number of transmission layers to be transmitted; sorting a plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); and assigning the number of transmission layers to the plurality of DMRS antenna ports in ascending order of the channel estimation MSE. ## Claims ### Claim 1 A method for mapping transmission layers to demodulation reference signal (DMRS) antenna ports, the method comprising: determining a number of transmission layers to be transmitted; sorting a plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); and assigning the number of transmission layers to the plurality of DMRS antenna ports in ascending order of the channel estimation MSE. ### Claim 2 (depends on 1) The method of claim 1, further comprising multiplexing DMRSs for the plurality of DMRS antenna ports in a comb fashion, wherein a number of combs is greater than 2. ### Claim 3 (depends on 1) The method of claim 1, wherein DMRS tones for each of the plurality of DMRS antenna ports are uniformly spaced in frequency. ### Claim 4 (depends on 1) The method of claim 1, wherein the plurality of DMRS antenna ports comprises greater than two DMRS antenna ports. ### Claim 5 (depends on 1) The method of claim 1, wherein the channel estimation MSE is highest for DMRS antenna ports for combs having a largest worst-case distance from edges of a band of subcarrier frequencies in a resource block. ### Claim 6 (depends on 5) The method of claim 5, wherein DMRS antenna ports having DMRS tones on the combs with a same worst-case distance from the edges of the band are mirror images of each other, and wherein the assigning transmission layers to the plurality of DMRS antenna ports further comprises assigning transmission layers to unassigned mirror image DMRS antenna ports in any order. ### Claim 7 (depends on 5) The method of claim 5, wherein the assigning the number of transmission layers to the plurality of DMRS antenna ports comprises: assigning a first transmission layer to a DMRS antenna port for a comb with a smallest worst-case distance from the edges of the band; assigning a second transmission layer to a DMRS antenna port for a comb with a next smallest worst-case distance from the edges of the band; and assigning an n-th transmission layer to a DMRS antenna port for a comb with an n-th smallest worst-case distance from the edges of the band, where n is a number of DMRS antenna ports. ### Claim 8 (depends on 7) The method of claim 7, further comprising multiplexing the DMRSs for the plurality of DMRS antenna ports in a comb fashion, wherein a number of combs is greater than 2 ### Claim 9 (depends on 7) The method of claim 7, wherein DMRS tones for each of the plurality of DMRS antenna port are uniformly spaced in frequency. ### Claim 10 (depends on 1) The method of claim 1, wherein the DMRSs for the plurality of DMRS antenna ports assigned to transmission layers are frequency division multiplexed. ### Claim 11 (depends on 1) The method of claim 1, wherein the DMRSs for a first set of the plurality of DMRS antenna ports assigned to the number of transmission layers are frequency division multiplexed; and the DMRSs for a second set of the plurality of DMRS antenna ports assigned to the number of transmission layers are frequency division multiplexed, and code division multiplexed with the DMRSs for the first set of the plurality of DMRS antenna ports. ### Claim 12 A method for mapping mobile communication devices to demodulation reference signal (DMRS) antenna ports, the method comprising: determining a number of the mobile communication devices to be assigned to a plurality of DMRS antenna ports; sorting the plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); sorting the number of the mobile communication devices in descending order of a downlink (DL) spectral efficiency (SE); and assigning the number of the mobile communication devices to the plurality of DMRS antenna ports in descending order of the DL SE and ascending order of the channel estimation MSE. ### Claim 13 (depends on 12) The method of claim 12, further comprising multiplexing the DMRSs for the plurality of DMRS antenna ports in a comb fashion, wherein a number of combs is greater than 2. ### Claim 14 (depends on 12) The method of claim 12, wherein DMRS tones for each of the plurality of DMRS antenna port are uniformly spaced in frequency. ### Claim 15 (depends on 12) The method of claim 12, wherein the assigning the number of the mobile communication devices comprises assigning a mobile communication device with a highest SE to a DMRS antenna port with a smallest channel estimation MSE, and a mobile communication device with a lowest SE to a DMRS antenna port with a highest channel estimation MSE. ### Claim 16 (depends on 12) The method of claim 12, wherein the plurality of the DMRS antenna ports comprises greater than two DMRS antenna ports. ### Claim 17 (depends on 12) The method of claim 12, wherein the channel estimation MSE is highest for DMRS antenna ports for combs having a largest worst-case distance from edges of a band of subcarrier frequencies in a resource block. ### Claim 18 (depends on 17) The method of claim 17, wherein the DMRS antenna ports having DMRS tones on the combs with a same worst-case distance from the edges of the band are mirror images of each other, and wherein the assigning the number of the mobile communication devices to the plurality of DMRS antenna ports further comprises assigning the number of the mobile communication devices to unassigned mirror image DMRS antenna ports in any order. ### Claim 19 (depends on 17) The method of claim 17, wherein a mobile communication device having a higher data throughput has a higher DL SE. ### Claim 20 (depends on 19) The method of claim 19, wherein the assigning the number of mobile communication devices to the plurality of the DMRS antenna ports comprises: assigning a first mobile communication device having a highest DL SE to a DMRS antenna port for a comb with a smallest worst-case distance from the edges of the band; assigning a second mobile communication device having a next highest DL SE to a DMRS antenna port for a comb with a next smallest worst-case distance from the edges of the band; and assigning an n-th mobile communication device having an n-th highest DL SE to a DMRS antenna port for a comb with an n-th smallest worst-case distance from the edges of the band, where n is a number of the DMRS antenna ports. ### Claim 21 (depends on 12) The method of claim 12, wherein the DMRSs for the DMRS antenna ports assigned to transmission layers transmitted to each of the number of the mobile communication devices are frequency division multiplexed. ### Claim 22 (depends on 12) The method of claim 12, wherein the DMRSs for a first set of the plurality of DMRS antenna ports assigned to transmission layers transmitted to each of the number of mobile communication devices are frequency division multiplexed; and the DMRSs for a second set of the plurality of DMRS antenna ports assigned to the transmission layers transmitted to each of the number of mobile communication devices are frequency division multiplexed, and code division multiplexed with the DMRSs for the first set of the plurality of DMRS antenna ports. ### Claim 23 A non-transitory computer readable medium having stored thereon instructions for causing one or more processors to perform operations comprising: determining a number of mobile communication devices to be assigned to a plurality of DMRS antenna ports; sorting the plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); sorting the number of mobile communication devices in descending order of a downlink (DL) spectral efficiency (SE); and assigning the number of mobile communication devices to the plurality of DMRS antenna ports in descending order of the DL SE and ascending order of the channel estimation MSE. ### Claim 24 (depends on 23) The non-transitory computer readable medium having stored therein instructions as defined in claim 23, wherein the plurality of the DMRS antenna ports comprises greater than two DMRS antenna ports. ### Claim 25 (depends on 23) The non-transitory computer readable medium having stored therein instructions as defined in claim 23, wherein the channel estimation MSE is highest for DMRS antenna ports for combs having a largest worst-case distance from edges of a band of subcarrier frequencies in a resource block. ### Claim 26 (depends on 25) The non-transitory computer readable medium having stored therein instructions as defined in claim 25, wherein the DMRS antenna ports having DMRS tones on the combs with a same worst-case distance from the edges of the band are mirror images of each other, and wherein the assigning the number of the mobile communication devices to the plurality of the DMRS antenna ports further comprises assigning the number of mobile communication devices to unassigned mirror image DMRS antenna ports in any order. ### Claim 27 (depends on 25) The non-transitory computer readable medium having stored therein instructions as defined in claim 25, wherein a mobile communication device having a higher data throughput has a higher DL SE. ### Claim 28 (depends on 27) The non-transitory computer readable medium having stored therein instructions as defined in claim 27, wherein the assigning the number of the mobile communication devices to the plurality of the DMRS antenna ports comprises: assigning a first mobile communication device having a highest DL SE to a DMRS antenna port for a comb with a smallest worst-case distance from the edges of the band; assigning a second mobile communication device having a next highest DL SE to a DMRS antenna port for a comb with a next smallest worst-case distance from the edges of the band; and assigning an n-th mobile communication device having an n-th highest DL SE to a DMRS antenna port for a comb with an n-th smallest worst-case distance from the edges of the band, where n is a number of the DMRS antenna ports. ### Claim 29 (depends on 23) The non-transitory computer readable medium having stored therein instructions as defined in claim 23, wherein the DMRSs for the DMRS antenna ports assigned to transmission layers transmitted to each of the number of the mobile communication devices are frequency division multiplexed. ### Claim 30 (depends on 23) The non-transitory computer readable medium having stored therein instructions as defined in claim 23, wherein the DMRSs for a first set of the plurality of DMRS antenna ports assigned to transmission layers transmitted to each of the number of mobile communication devices are frequency division multiplexed; and the DMRSs for a second set of the plurality of DMRS antenna ports assigned to the transmission layers transmitted to each of the number of mobile communication devices are frequency division multiplexed, and code division multiplexed with the DMRSs for the first set of the plurality of DMRS antenna ports. ### Claim 31 An apparatus for mapping transmission layers to demodulation reference signal (DMRS) antenna ports, the apparatus comprising: means for determining a number of transmission layers to be transmitted; means for sorting a plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); and means for assigning the number of transmission layers to the plurality of DMRS antenna ports in ascending order of the channel estimation MSE. ### Claim 32 (depends on 31) The apparatus of claim 31, further comprising means for multiplexing DMRSs for the DMRS antenna ports in a comb fashion, wherein the number of combs is greater than 2. ### Claim 33 (depends on 31) The apparatus of claim 31, wherein DMRS tones for each of the plurality of DMRS antenna ports are uniformly spaced in frequency. ### Claim 34 (depends on 31) The apparatus of claim 31, wherein the plurality of the DMRS antenna ports comprises greater than two DMRS antenna ports. ### Claim 35 (depends on 31) The apparatus of claim 31, wherein the channel estimation MSE is highest for DMRS antenna ports for combs having a largest worst-case distance from edges of a band of subcarrier frequencies in a resource block. ### Claim 36 (depends on 35) The apparatus of claim 35, wherein the DMRS antenna ports having DMRS tones on combs with a same worst-case distance from the edges of the band are mirror images of each other, and wherein the means for assigning transmission layers to the plurality of DMRS antenna ports further comprises means for assigning transmission layers to unassigned mirror image DMRS antenna ports in any order. ### Claim 37 (depends on 35) The apparatus of claim 35, wherein the means for assigning the transmission layers to the plurality of DMRS antenna ports comprises: means for assigning a first transmission layer to a DMRS antenna port for a comb with a smallest worst-case distance from the edges of the band; means for assigning a second transmission layer to a DMRS antenna port for a comb with a next smallest worst-case distance from the edges of the band; and means for assigning an n-th transmission layer to a DMRS antenna port for a comb with an n-th smallest worst-case distance from the edges of the band, where n is a number of DMRS antenna ports. ### Claim 38 (depends on 37) The apparatus of claim 37, further comprising means for multiplexing the DMRSs for the antenna ports in a comb fashion, wherein a number of combs is more than 2. ### Claim 39 (depends on 37) The apparatus of claim 37, wherein DMRS tones for each antenna port are uniformly spaced in frequency. ### Claim 40 (depends on 31) The apparatus of claim 31, wherein the DMRSs for the plurality of DMRS antenna ports assigned to the transmission layers are frequency division multiplexed. ### Claim 41 (depends on 31) The apparatus of claim 31, wherein the DMRSs for a first set of the plurality of DMRS antenna ports assigned to the number of transmission layers are frequency division multiplexed; and the DMRSs for a second set of the plurality of DMRS antenna ports assigned to the number of transmission layers are frequency division multiplexed, and code division multiplexed with the DMRSs for the first set of the plurality of DMRS antenna ports. ### Claim 42 An apparatus for mapping mobile communication devices to demodulation reference signal (DMRS) antenna ports, the method comprising: means for determining a number of the mobile communication devices to be assigned to a plurality of DMRS antenna ports; means for sorting the plurality of DMRS antenna ports in ascending order based on a channel estimation mean square error (MSE); means for sorting the number of the mobile communication devices in descending order of a downlink (DL) spectral efficiency (SE); and means for assigning the number of the mobile communication devices to the plurality of DMRS antenna ports in descending order of the DL SE and ascending order of the channel estimation MSE. ### Claim 43 (depends on 42) The apparatus of claim 42, further comprising means for multiplexing the DMRSs for the antenna ports in a comb fashion, wherein a number of combs is more than 2. ### Claim 44 (depends on 42) The apparatus of claim 42, wherein DMRS tones for each of the plurality of DMRS antenna port are uniformly spaced in frequency. ### Claim 45 (depends on 42) The apparatus of claim 42, wherein the means for assigning the number of the mobile communication devices comprises means for assigning a mobile communication device with a highest SE to a DMRS antenna port with a smallest MSE, and a mobile communication device with a lowest SE to a DMRS antenna port with a highest MSE. ### Claim 46 (depends on 42) The apparatus of claim 42, wherein the plurality of the DMRS antenna ports comprises greater than two DMRS antenna ports. ### Claim 47 (depends on 42) The apparatus of claim 42, wherein the channel estimation MSE is highest for DMRS antenna ports for combs having a largest worst-case distance from edges of a band of subcarrier frequencies in a resource block. ### Claim 48 (depends on 47) The apparatus of claim 47, wherein the DMRS antenna ports having DMRS tones on the combs with a same worst-case distance from the edges of the band are mirror images of each other, and wherein the means for assigning the number of the mobile communication devices to the plurality of the DMRS antenna ports further comprises means for assigning the number of the mobile communication devices to unassigned mirror image DMRS antenna ports in any order. ### Claim 49 (depends on 47) The apparatus of claim 47, wherein a mobile communication device having a higher data throughput has a higher DL SE. ### Claim 50 (depends on 49) The apparatus of claim 49, wherein the means for assigning the number of mobile communication devices to the plurality of DMRS antenna ports comprises: means for assigning a first mobile communication device having a highest DL SE to a DMRS antenna port for a comb with a smallest worst-case distance from the edges of the band; means for assigning a second mobile communication device having a next highest DL SE to a DMRS antenna port for a comb with a next smallest worst-case distance from the edges of the band; and means for assigning an n-th mobile communication device having an n-th highest DL SE to a DMRS antenna port for a comb with an n-th smallest worst-case distance from the edges of the band, where n is a number of the DMRS antenna ports. ### Claim 51 (depends on 42) The apparatus of claim 42, wherein the DMRSs for the DMRS antenna ports assigned to transmission layers transmitted to each of the number of the mobile communication devices are frequency division multiplexed. ### Claim 52 (depends on 42) The apparatus of claim 42, wherein the DMRSs for a first set of the plurality of DMRS antenna ports assigned to transmission layers transmitted to each of the number of the mobile communication devices are frequency division multiplexed; and the DMRSs for a second set of the plurality of DMRS antenna ports assigned to the transmission layers transmitted to each of the number of the mobile communication devices are frequency division multiplexed, and code division multiplexed with the DMRSs for the first set of the plurality of DMRS antenna ports.