# US 2020/0404580 A1 · Wireless communications over unlicensed radio frequency spectrum > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0404580 A1 - Document ID: US20200404580A1 - Status: Published application - Kind: A1 - Application number: 16/921,617 - Filed: 2020-07-06 - Published: 2020-12-24 - Earliest claimed: 2014-06-13 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Durga Prasad Malladi; Yongbin Wei; Tao Luo; Aleksandar Damnjanovic - Web page: https://patentgrep.com/patent/US20200404580A1 ## CPC - H04W 48/08: Access restriction or access information delivery, e.g. discovery data delivery (signalling during connection H04W76/00) - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04W 48/10: using broadcasted information - H04W 48/12: using downlink control channel - H04W 74/08: Non-scheduled access, e.g. ALOHA (hybrid access H04W74/02) - H04J 2011/0006: {with CDM/CDMA} - H04L 5/001: {the frequencies being arranged in component carriers} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract Techniques for transmitting and receiving wireless communications over an unlicensed radio frequency spectrum band are disclosed, including techniques for transmitting and receiving system information blocks over the unlicensed radio frequency spectrum band, techniques for gaining access to the unlicensed radio frequency spectrum band by performing extended clear channel assessments (ECCAs), techniques for transmitting and receiving synchronization signals and reference signals over the unlicensed radio frequency spectrum band, techniques for identifying starting times of downlink transmissions over the unlicensed radio frequency spectrum band, techniques for transmitting and receiving clear channel assessment (CCA)-exempt transmissions over the unlicensed radio frequency spectrum band, techniques for performing random access over the unlicensed radio frequency spectrum band, and techniques for dynamically modifying a transmission mode over the unlicensed radio frequency spectrum band. ## Claims ### Claim 1 (canceled) ### Claim 2 A method of wireless communication, comprising: transmitting at least one system information block (SIB), wherein the SIB comprises a Multiple Input Multiple Output (MIMO) parameter and a modulation parameter associated with a communication link over an unlicensed radio frequency spectrum band; and receiving a transmission over the unlicensed radio frequency spectrum band according to a selected transmission mode based at least on the MIMO parameter and the modulation parameter, wherein the selected transmission mode comprises an orthogonal frequency division multiplexing (OFDM) transmission mode when the MIMO parameter indicates that the communication link supports MIMO transmissions and the selected transmission mode comprises a single-carrier frequency division multiple access (SC-FDMA) transmission mode when the modulation parameter for the communication link is less than or equal to a threshold. ### Claim 3 (depends on 2) The method of claim 2, wherein the modulation parameter is a modulation and coding scheme (MCS) parameter. ### Claim 4 (depends on 2) The method of claim 2, wherein the receiving comprises receiving an uplink transmission and the selected transmission mode comprises an uplink transmission mode of the communication link. ### Claim 5 (depends on 4) The method of claim 4, wherein the uplink transmission mode of the communication link matches a downlink transmission mode of the communication link. ### Claim 6 (depends on 2) The method of claim 2, wherein the receiving comprises receiving over a plurality of interlaced resource blocks. ### Claim 7 (depends on 2) The method of claim 2, wherein the selected transmission mode comprises the OFDM transmission mode, and wherein receiving comprises receiving a demodulation reference signal for the communication link according to a subset of resource elements of one or more symbols of one or more resource blocks. ### Claim 8 (depends on 7) The method of claim 7, wherein, for the OFDM transmission mode, the receiving comprises receiving data in resource elements of the one or more symbols other than the subset of resource elements. ### Claim 9 (depends on 2) The method of claim 2, wherein the selected transmission mode comprises the SC-FDMA transmission mode, the receiving comprises receiving a demodulation reference signal for the communication link using each resource element of one or more symbols of one or more resource blocks. ### Claim 10 An apparatus for wireless communication, comprising: a processor; memory in electronic communication with the processor; and instructions stored in the memory, wherein the instructions are executable by the processor to: transmit at least one system information block (SIB), wherein the SIB comprises a Multiple Input Multiple Output (MIMO) parameter and a modulation parameter associated with a communication link over an unlicensed radio frequency spectrum band; and receive a transmission over the unlicensed radio frequency spectrum band according to a selected transmission mode based at least on the MIMO parameter and the modulation parameter, wherein the selected transmission mode comprises an orthogonal frequency division multiplexing (OFDM) transmission mode when the MIMO parameter indicates that the communication link supports MIMO transmissions and the selected transmission mode comprises a single-carrier frequency division multiple access (SC-FDMA) transmission mode when the modulation parameter for the communication link is less than or equal to a threshold. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the modulation parameter is a modulation and coding scheme (MCS) parameter. ### Claim 12 (depends on 10) The apparatus of claim 10, wherein receive comprises receive an uplink transmission and the selected transmission mode comprises an uplink transmission mode of the communication link. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the uplink transmission mode of the communication link matches a downlink transmission mode of the communication link. ### Claim 14 (depends on 10) The apparatus of claim 10, wherein receive comprises receive over a plurality of interlaced resource blocks. ### Claim 15 (depends on 10) The apparatus of claim 10, wherein the selected transmission mode comprises the OFDM transmission mode, and wherein receive comprises receive a demodulation reference signal for the communication link according to a subset of resource elements of one or more symbols of one or more resource blocks. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein, for the OFDM transmission mode, receive comprises receive data in resource elements of the one or more symbols other than the subset of resource elements. ### Claim 17 (depends on 10) The apparatus of claim 10, wherein the selected transmission mode comprises the SC-FDMA transmission mode, and wherein receive comprises receive a demodulation reference signal for the communication link using each resource element of one or more symbols of one or more resource blocks. ### Claim 18 A non-transitory computer-readable medium storing code for wireless communication, code comprising instructions executable to: transmit at least one system information block (SIB), wherein the SIB comprises a Multiple Input Multiple Output (MIMO) parameter and a modulation parameter associated with a communication link over an unlicensed radio frequency spectrum band; and receive a transmission over the unlicensed radio frequency spectrum band according to a selected transmission mode based at least on the MIMO parameter and the modulation parameter, wherein the selected transmission mode comprises an orthogonal frequency division multiplexing (OFDM) transmission mode when the MIMO parameter indicates that the communication link supports MIMO transmissions and the selected transmission mode comprises a single-carrier frequency division multiple access (SC-FDMA) transmission mode when the modulation parameter for the communication link is less than or equal to a threshold. ### Claim 19 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the modulation parameter is a modulation and coding scheme (MCS) parameter. ### Claim 20 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the instructions executable to receive comprise instructions executable to receive an uplink transmission and the selected transmission mode comprises an uplink transmission mode of the communication link. ### Claim 21 (depends on 20) The non-transitory computer-readable medium of claim 20, wherein the uplink transmission mode of the communication link matches a downlink transmission mode of the communication link. ### Claim 22 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the instructions executable to receive comprise instructions executable to receive over a plurality of interlaced resource blocks. ### Claim 23 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the selected transmission mode comprises the OFDM transmission mode, and wherein the instructions executable to receive comprise instructions executable to receive a demodulation reference signal for the communication link using a subset of resource elements of one or more symbols of one or more resource blocks. ### Claim 24 (depends on 23) The non-transitory computer-readable medium of claim 23, wherein, for the OFDM transmission mode, the instructions executable to receive comprise instructions executable to receive data in resource elements of the one or more symbols other than the subset of resource elements. ### Claim 25 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the selected transmission mode comprises the SC-FDMA transmission mode, the instructions executable to receive comprise instructions executable to receive a demodulation reference signal for the communication link using each resource element of one or more symbols of one or more resource blocks.