# US 9,521,537 B2 · Methods and arrangements for device discovery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,537 B2 - Document ID: US9521537B2 - Status: Granted - Kind: B2 - Application number: 14/403,603 - Filed: 2014-10-07 - Published: 2015-10-22 - Granted: 2016-12-13 - Earliest claimed: 2013-10-07 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget L M Ericsson (publ) - Inventors: Stefano Sorrentino - Web page: https://patentgrep.com/patent/US9521537B2 ## CPC - H04W 8/005: {Discovery of network devices, e.g. terminals} - H04L 1/1678: {where the control information is for timing, e.g. time stamps} - H04W 12/08: Access security - H04W 12/10: Integrity - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04L 63/0407: {wherein the identity of one or more communicating identities is hidden (cryptographic mechanisms or cryptographic arrangements for anonymous credentials or for identity based cryptographic systems H04L9/00)} - H04W 12/02: Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII] - H04W 76/14: Direct-mode setup - H04W 88/02: Terminal devices - 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) ## Abstract The present disclosure relates to methods and devices for transmission of discovery signal signals and detection of discovery signal signals for device-to-device communication. According to some aspects, the disclosure relates to a method executed in a second wireless terminal for discovering a first wireless terminal, wherein the second wireless terminal 20 is configured with a set of one or more identities of wireless terminals with which device-to-device, D2D, communication is possible. The method comprises the following steps detecting a control signal transmitted from the first wireless terminal, wherein the control signal carries an identity and decoding S13 the received signal. The wireless terminal then, for each identity in the set, hashes S14 a reference control signal comprising an identity of the wireless terminal, taking a time stamp used for the control signal transmission as one input parameter of the hashing function and determines S15 if an output signal of the hashing matches the decoded signal, until all the identities in the set have been selected or until a match is found. ## Claims ### Claim 1 A method executed in a second wireless terminal for discovering a first wireless terminal, wherein the second wireless terminal is configured with a set of one or more identities of wireless terminals with which device-to-device (D2D) communication is possible, the method comprising: detecting a control signal transmitted from the first wireless terminal, wherein the control signal carries an identity; decoding the control signal; and for each identity in the set, executing the following steps until all the identities in the set have been selected or until a match is found: hashing a reference control signal comprising the identity from the set, taking a time stamp used for the control signal transmission as one input parameter of the hashing function, and determining whether the output signal of the hashing matches the decoded control signal. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining involves comparing the output signal of the hashing and the decoded control signal. ### Claim 3 (depends on 1) The method of claim 1, wherein the method further comprises descrambling the control signal. ### Claim 4 (depends on 1) The method of claim 1, wherein the determining involves partial matching of the hashed reference control signal and the decoded control signal. ### Claim 5 (depends on 4) The method of claim 4, wherein the partial matching implies that a match is declared even though only a subset of the compared bits matches. ### Claim 6 (depends on 4) The method of claim 4, wherein partial matching involves comparing only a subset of the number of bits in the output signal of the hashing with the decoded control signal. ### Claim 7 (depends on 1) The method of claim 1, wherein the identity carried by the control signal comprises an identity of the first wireless terminal. ### Claim 8 A second wireless terminal adapted for discovering a first wireless terminal, wherein the second wireless terminal is configured with a set of one or more identities of wireless terminals with which device-to-device (D2D) communication is possible, the second wireless terminal comprising: receiver circuitry adapted to detect a control signal transmitted from the first wireless terminal, wherein the control signal carries an identity; baseband circuitry adapted to decode the control signal; and processing circuitry adapted to, for each identity in the set, repeat the following steps until all the identities in the set have been selected or until a match is found: i. hash a reference control signal comprising the identity from the set, taking a time stamp used for the control signal transmission as one input parameter of the hashing function, and ii. compare an output signal of the hashing with the decoded control signal. ### Claim 9 (depends on 8) The second wireless terminal of claim 8, wherein the processing circuitry is further adapted to descramble the control signal. ### Claim 10 (depends on 8) The second wireless terminal of claim 8, wherein the comparing involves partial matching of the hashed reference control signal and the decoded control signal. ### Claim 11 (depends on 10) The second wireless terminal of claim 10, wherein the partial matching implies that a match is declared even though only a subset of the compared bits matches. ### Claim 12 (depends on 10) The second wireless terminal of claim 10, wherein partial matching involves comparing only a subset of the number of bits in the output signal of the hashing with the decoded control signal. ### Claim 13 (depends on 8) The second wireless terminal of claim 8, wherein the second wireless terminal is a user equipment. ### Claim 14 A non-transitory computer-readable medium comprising, stored thereupon, computer readable code that, when run on a wireless terminal configured with a set of one or more identities of wireless terminals with which device-to-device (D2D) communication is possible, causes the wireless terminal to: detect a control signal transmitted from another wireless terminal, wherein the control signal carries an identity; decode the control signal; and for each identity in the set, execute the following steps until all the identities in the set have been selected or until a match is found: hashing a reference control signal comprising the identity from the set, taking a time stamp used for the control signal transmission as one input parameter of the hashing function, and determining whether the output signal of the hashing matches the decoded control signal.