# US 10,771,560 B2 · Band scan for narrowband communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,560 B2 - Document ID: US10771560B2 - Status: Granted - Kind: B2 - Application number: 16/255,435 - Filed: 2019-01-23 - Published: 2020-07-23 - Granted: 2020-09-08 - Earliest claimed: 2019-01-23 - Assignees: QUALCOMM Incorporated - Applicants: Qualcomm Incorporated - Inventors: Raghavendra Shyam Ananda; Srikanth Menon; Ganesh Nagamani; Anand Rajurkar - Web page: https://patentgrep.com/patent/US10771560B2 ## CPC - H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks - H04W 48/16: Discovering, processing access restriction or access information - H04L 27/0006: {Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio (for spectrum sharing between different networks H04W16/14)} - H04W 48/10: using broadcasted information - H04W 56/001: {Synchronization between nodes} - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - 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 A user equipment (UE) performs wireless communication by starting a scan of an absolute radio frequency channel number (ARFCN) configured for performing a narrowband communication. The UE determines, based on a spectral characteristic of a phase of a signal in the ARFCN, whether a cellular communication is deployed in the ARFCN. The UE may then terminate the scan of the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is deployed in the ARFCN. Alternatively, the UE may proceed with a synchronization signal search on the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is not deployed in the ARFCN. ## Claims ### Claim 1 A method of wireless communication at a user equipment (UE), comprising: starting a scan of an absolute radio frequency channel number (ARFCN) configured for performing a narrowband communication; determining, based on a spectral characteristic of a phase of a signal in the ARFCN, whether a cellular communication is deployed in the ARFCN; terminating the scan of the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is deployed in the ARFCN; and proceeding with a synchronization signal search on the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is not deployed in the ARFCN. ### Claim 2 (depends on 1) The method of claim 1, further comprising: starting, subsequent to the terminating of the scan of the ARFCN, another scan of another ARFCN configured for performing the narrowband communication. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining an overlap between a frequency band associated with the cellular communication and a frequency band associated with the ARFCN; and wherein at least the determining of whether the cellular communication is deployed in the ARFCN is performed in response to the determining of the overlap. ### Claim 4 (depends on 1) The method of claim 1, further comprising: performing a power scan on the ARFCN to detect a power of the signal in the ARFCN; and determining whether the power of the signal in the ARFCN is greater than a Received Signal Strength Indicator (RSSI) threshold. ### Claim 5 (depends on 4) The method of claim 4, wherein the determining of whether the cellular communication is deployed in the ARFCN is performed in response to the power of the signal in the ARFCN being greater than the RSSI threshold. ### Claim 6 (depends on 4) The method of claim 4, further comprising: initiating the synchronization signal search on the ARFCN in response to the power of the signal in the ARFCN being less than the RSSI threshold. ### Claim 7 (depends on 4) The method of claim 4, wherein the performing of the synchronization signal search on the ARFCN comprises performing at least one of a primary synchronization signal (PSS) scan or a secondary synchronization signal (SSS) scan on the ARFCN. ### Claim 8 (depends on 1) The method of claim 1, wherein the terminating comprises aborting the synchronization signal search on the ARFCN. ### Claim 9 (depends on 1) The method of claim 1, further comprising: determining whether the synchronization signal search on the ARFCN is successful; selecting the ARFCN for the narrowband communication in response to the synchronization signal search on the ARFCN being successful; and starting another scan of another ARFCN configured for performing the narrowband communication in response to a failure of the synchronization signal search on the ARFCN. ### Claim 10 (depends on 9) The method of claim 9, further comprising: decoding a Narrowband Physical Broadcast Channel (NPBCH) in response to the synchronization signal search on the ARFCN being successful. ### Claim 11 (depends on 1) The method of claim 1, wherein the spectral characteristic of the phase of the signal in the ARFCN comprises a second order difference of the phase of the signal in the ARFCN. ### Claim 12 (depends on 1) The method of claim 1, wherein the ARFCN comprises an E-UTRA ARFCN (EARFCN); wherein the cellular communication comprises a Global System for Mobile communications (GSM) communication; and wherein the narrowband communication comprises narrowband Internet-of-Things (NB-IoT) communication. ### Claim 13 (depends on 1) The method of claim 1, wherein the spectral characteristic of the phase of the signal in the ARFCN comprises an average over a number of samples of a square of a second order difference of the phase of the signal in the ARFCN. ### Claim 14 (depends on 13) The method of claim 13, wherein the determining comprises: comparing the average with a threshold; deciding that the cellular communication is deployed in the ARFCN in response to the average being smaller than the threshold; and deciding that the cellular communication is not deployed in the ARFCN in response to the average being equal to or larger than the threshold. ### Claim 15 (depends on 13) The method of claim 13, wherein the determining comprises: calculating a first order difference of the phase of the signal based on baseband samples of the signal; wrapping the first order difference of the phase of the signal to obtain a wrapped first order difference of the phase of the signal; calculating the second order difference of the phase of the signal based on the wrapped first order difference of the phase of the signal; and calculating the average over the number of samples of the square of the second order difference of the phase of the signal in the ARFCN. ### Claim 16 (depends on 15) The method of claim 15, wherein the baseband samples of the signal have a sampling rate associated with a bandwidth of the cellular communication. ### Claim 17 (depends on 15) The method of claim 15, wherein the calculating of the first order difference of the phase of the signal comprises obtaining a product of a conjugate of each sample with a previous sample; and wherein the wrapping of the first order difference of the phase of the signal comprises wrapping the first order difference of the phase of the signal to an area between −π and +π. ### Claim 18 (depends on 15) The method of claim 15, wherein the calculating of the second order difference of the phase of the signal comprises applying a frequency domain filter to the wrapped first order difference of the phase of the signal. ### Claim 19 A user equipment (UE) for wireless communication, comprising: a memory; and at least one processor coupled to the memory and configured to: start a scan of an absolute radio frequency channel number (ARFCN) configured for performing a narrowband communication; determine, based on a spectral characteristic of a phase of a signal in the ARFCN, whether a cellular communication is deployed in the ARFCN; terminate the scan of the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is deployed in the ARFCN; and proceed with a synchronization signal search on the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is not deployed in the ARFCN. ### Claim 20 A computer-readable medium storing computer executable code, comprising code to: start a scan of an absolute radio frequency channel number (ARFCN) configured for performing a narrowband communication; determine, based on a spectral characteristic of a phase of a signal in the ARFCN, whether a cellular communication is deployed in the ARFCN; terminate the scan of the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is deployed in the ARFCN; and proceed with a synchronization signal search on the ARFCN in response to the spectral characteristic of the phase of the signal in the ARFCN indicating that the cellular communication is not deployed in the ARFCN.