# US 9,438,397 B2 · Pseudo-random sequence mapping in wireless communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,397 B2 - Document ID: US9438397B2 - Status: Granted - Kind: B2 - Application number: 14/635,852 - Filed: 2015-03-02 - Published: 2015-06-18 - Granted: 2016-09-06 - Earliest claimed: 2007-06-05 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Durga Prasad Malladi; Juan Montojo - Web page: https://patentgrep.com/patent/US9438397B2 ## CPC - H04J 11/0069: {Cell search, i.e. determining cell identity [cell-ID] (design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655)} - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - 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)} - H04L 25/03866: {using scrambling} - H04L 27/2607: {Cyclic extensions} - H04L 27/2613: {Structure of the reference signals} - H04W 56/001: {Synchronization between nodes} - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methodologies are described that facilitate scrambling of downlink reference signals utilizing a pseudo-random sequence (PRS) corresponding to a primary synchronization code (PSC) and secondary synchronization code (SSC) combination. In an aspect, a method includes receiving a scrambled downlink reference signal, determining a pseudo-random sequence based on received PSC and SSC, and descrambling a portion of subframes of the downlink reference signal according to the pseudo-random sequence and a determined cyclic prefix length for one or more of the portion of subframes. ## Claims ### Claim 1 A method for wireless communications, comprising: receiving a scrambled downlink reference signal; determining a pseudo-random sequence based on received primary and secondary synchronization codes that directly map to the pseudo-random sequence; and descrambling a portion of subframes of the scrambled downlink reference signal according to the pseudo-random sequence and a determined cyclic prefix length for one or more of the portion of subframes. ### Claim 2 (depends on 1) The method of claim 1, wherein the primary and secondary synchronization codes are received in a disparate signal from a transmitter. ### Claim 3 (depends on 1) The method of claim 1, wherein the descrambling is performed over subframes with a cyclic prefix length above a specified threshold. ### Claim 4 (depends on 1) The method of claim 1, further comprising descrambling a portion of subframes of the downlink reference signal having a cyclic prefix length less than a specified threshold based at least in part on a pseudo-random sequence corresponding to the secondary synchronization code and an orthogonal sequence. ### Claim 5 (depends on 1) The method of claim 1, further comprising evaluating a first subframe to determine the cyclic prefix length for the first subframe and possible cyclic prefix lengths for remaining subframes. ### Claim 6 (depends on 5) The method of claim 5, wherein a dynamic broadcast channel in a subframe provides the cyclic prefix lengths of the remaining subframes. ### Claim 7 (depends on 1) The method of claim 1, further comprising identifying a transmitter based at least in part on the primary and secondary synchronization codes. ### Claim 8 (depends on 1) The method of claim 1, further comprising extracting the primary and secondary synchronization codes from the downlink reference signal. ### Claim 9 A wireless communications apparatus, comprising: at least one processor configured to: receive a scrambled downlink reference signal, determine a pseudo-random sequence based on received primary and secondary synchronization codes that directly map to the pseudo-random sequence, and descramble a portion of subframes of the scrambled downlink reference signal according to the pseudo-random sequence and a determined cyclic prefix length for one or more of the portion of subframes; and a memory coupled to the at least one processor. ### Claim 10 (depends on 9) The wireless communications apparatus of claim 9, wherein the cyclic prefix length of the one or more subframes exceeds a specified threshold and the descrambling is performed utilizing a pseudo-random sequence determined from a primary and secondary synchronization code combination in the scrambled downlink reference signal. ### Claim 11 (depends on 10) The wireless communications apparatus of claim 10, wherein the primary and secondary synchronization code combination identifies a transmitter of the scrambled downlink reference signal. ### Claim 12 (depends on 9) The wireless communications apparatus of claim 9, wherein the cyclic prefix length of the one or more subframes is below a specified threshold and the descrambling is performed utilizing a pseudo-random sequence determined from a secondary synchronization code in the reference signal and a determined orthogonal sequence. ### Claim 13 (depends on 9) The wireless communications apparatus of claim 9, wherein the one or more subframes is a first subframe of the reference signal. ### Claim 14 (depends on 13) The wireless communications apparatus of claim 13, wherein the cyclic prefix of the first subframe is of normal length and the at least one processor is further configured to determine cyclic prefix lengths for the remaining subframes by evaluating a dynamic broadcast channel in the downlink reference signal. ### Claim 15 (depends on 13) The wireless communications apparatus of claim 13, wherein the cyclic prefix of the first subframe is of an extended length and the at least one processor is further configured to determine the remaining subframes having extended cyclic prefix lengths. ### Claim 16 A non-transitory computer-readable medium, comprising: code for causing at least one computer to receive a scrambled downlink reference signal; code for causing the at least one computer to determine a pseudo-random sequence based on received primary and secondary synchronization codes that directly map to the pseudo-random sequence; and code for causing the at least one computer to descramble a portion of subframes of the scrambled downlink reference signal according to the pseudo-random sequence and a determined cyclic prefix length for one or more of the portion of subframes. ### Claim 17 (depends on 16) The non-transitory computer-readable medium of claim 16, further comprising code for causing the at least one computer to determine a cyclic prefix length for one or more subframes of the portion of the scrambled downlink reference signal. ### Claim 18 A method for wireless communications, comprising: generating a downlink reference signal comprising primary and secondary synchronization codes; scrambling the downlink reference signal based at least in part on a pseudo-random sequence that directly maps to combination of the primary and secondary synchronization codes; and transmitting the scrambled downlink reference signal. ### Claim 19 (depends on 18) The method of claim 18, wherein the scrambling is performed in a portion of subframes of the downlink reference signal having a cyclic prefix length above a specified threshold. ### Claim 20 (depends on 19) The method of claim 19, further comprising: scrambling a portion of subframes of the reference signal having a cyclic prefix length less than or equal to the threshold based at least in part on a pseudo-random sequence corresponding to the secondary synchronization code; and applying an orthogonal sequence to the scrambled subframes of the reference signal having a cyclic prefix length less than or equal to the threshold. ### Claim 21 (depends on 18) The method of claim 18, wherein the pseudo-random sequence corresponds to the secondary synchronization code and the primary synchronization code is a reuse factor for the pseudo-random sequence. ### Claim 22 (depends on 18) The method of claim 18, wherein the primary and secondary synchronization code combination identifies a transmitter of the reference signal. ### Claim 23 A wireless communications apparatus, comprising: at least one processor configured to: generate a downlink reference signal comprising primary and secondary synchronization codes, scramble the downlink reference signal based at least in part on a pseudo-random sequence that directly maps to combination of the primary and secondary synchronization codes, and transmit the scrambled downlink reference signal; and a memory coupled to the at least one processor. ### Claim 24 (depends on 23) The wireless communications apparatus of claim 23, wherein the at least one processor scrambles a portion of subframes of the downlink reference signal having a cyclic prefix length above a specified threshold. ### Claim 25 (depends on 24) The wireless communications apparatus of claim 24, wherein the at least one processor is further configured to: scramble a disparate portion of subframes of the reference signal having a cyclic prefix length less than the threshold based at least in part on a disparate pseudo-random sequence corresponding to the secondary synchronization code; and applying an orthogonal sequence to the disparate portion of subframes. ### Claim 26 (depends on 23) The wireless communications apparatus of claim 23, wherein the pseudo-random sequence corresponds to the secondary synchronization code and the primary synchronization code is a reuse factor for the pseudo-random sequence. ### Claim 27 (depends on 23) The wireless communications apparatus of claim 23, wherein the primary and secondary synchronization code combination identifies the wireless communications apparatus. ### Claim 28 A non-transitory computer-readable medium, comprising: code for causing at least one computer to generate a downlink reference signal comprising primary and secondary synchronization codes; code for causing the at least one computer to scramble the downlink reference signal based at least in part on a pseudo-random sequence that directly maps to combination of the primary and secondary synchronization codes; and code for causing the at least one computer to transmit the scrambled downlink reference signal. ### Claim 29 (depends on 28) The non-transitory computer-readable medium of claim 28, wherein the scrambling is performed in a portion of subframes of the downlink reference signal having a cyclic prefix length above a specified threshold.