# US 2018/0323903 A1 · Base station, controller, communication system, and interference avoidance method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323903 A1 - Document ID: US20180323903A1 - Status: Published application - Kind: A1 - Application number: 16/032,933 - Filed: 2018-07-11 - Published: 2018-11-08 - Earliest claimed: 2015-10-30 - Assignees: Panasonic Corporation - Applicants: Panasonic Corporation - Inventors: Hiroaki SUDO; Mitsuru UESUGI - Web page: https://patentgrep.com/patent/US20180323903A1 ## CPC - H04L 1/0056: {Systems characterized by the type of code used (H04L1/08 takes precedence)} - H04L 1/1893: {Physical mapping arrangements (physical resource mapping in general H04L5/00)} - H04L 5/0044: {Allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH} - H04L 5/006: {Quality of the received signal, e.g. BER, SNR, water filling} - H04L 1/0066: {Parallel concatenated codes} - H04L 5/0023: {Time-frequency-space} - H04W 88/08: Access point devices - 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 controller is provided that controls a plurality of base stations, each configured to communicate with a mobile station, using some carrier frequencies of a frequency band shared with another system. The controller includes a receiver that receives first frequency information from a first base station in communication with the mobile station, and second frequency information from a second base station, the second base station being a handover destination. The controller also includes a frequency selector that selects a carrier frequency for systematic-bit mapping and a carrier frequency for parity-bit mapping based on the first frequency information and the second frequency information. The controller further includes a signal-assignment-information generator that generates signal assignment information, indicating the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping, and a transmitter that transmits the signal assignment information to the first and the second base stations. ## Claims ### Claim 1 A controller that controls a plurality of base stations each configured to communicate with a mobile station, using some carrier frequencies of a frequency band shared with another system, the controller comprising: a receiver that receives first frequency information from a first base station in communication with the mobile station and second frequency information from a second base station, the first frequency information indicating a carrier frequency having an interference level lower than a threshold in an unused frequency band, a carrier frequency to which a systematic bit is mapped, and a carrier frequency to which a parity bit is mapped, the second frequency information indicating a carrier frequency having an interference level lower than the threshold in carrier frequencies of an unused frequency band, the second base station being a handover destination; a frequency selector that selects a carrier frequency for systematic-bit mapping and a carrier frequency for parity-bit mapping based on the first frequency information and the second frequency information; a signal-assignment-information generator that generates signal assignment information indicating the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping; and a transmitter that transmits the signal assignment information to the first and the second base stations. ### Claim 2 (depends on 1) The controller according to claim 1, wherein, when a number of carrier frequencies having an interference level smaller than the threshold in both the first and the second base stations is equal to or greater than a number required for assigning the systematic bit, the frequency selector selects the carrier frequency for systematic-bit mapping from among carrier frequencies having the interference level smaller than a predetermined value. ### Claim 3 (depends on 1) The controller according to claim 1, wherein, when a number of carrier frequencies having an interference level smaller than the threshold in both the first and the second base stations is less than a number required for assigning the systematic bit, the frequency selector selects a carrier frequency having the interference level smaller than a predetermined value as the carrier frequency for systematic-bit mapping, and selects the carrier frequency for systematic-bit mapping from among carrier frequencies to which the systematic bits are mapped in the first base station, for a remaining systematic bit. ### Claim 4 (depends on 1) The controller according to claim 1, wherein, when no carrier frequency having an interference level smaller than the threshold is present in either one of the first and the second base stations, the frequency selector selects the carrier frequency to which the systematic bit is mapped in the first base station, as the carrier frequency for systematic-bit mapping. ### Claim 5 (depends on 1) The controller according to claim 1, further comprising: a frequency determiner that determines whether or not frequency of a handover performed between the first and the second base stations is equal to or greater than reference frequency, wherein when the frequency of the handover is equal to or greater the reference frequency, the frequency selector alternately selects the carrier frequency for systematic-bit mapping from among carrier frequencies to which the systematic bits are mapped in the first base station and the carrier frequency having an interference level smaller than the threshold in the second base station, as the carrier frequency for systematic-bit mapping. ### Claim 6 (depends on 1) The controller according to claim 1, further comprising: a frequency determiner that determines whether or not frequency of a handover performed between the first and the second base stations is equal to or greater than reference frequency, wherein, when a number of carrier frequencies having an interference level smaller than the threshold in both the first and the second base stations is less than a number required for assigning the systematic bit, the frequency selector selects a carrier frequency having the interference level smaller than a predetermined value as the carrier frequency for systematic-bit mapping, and for a remaining systematic bit, when the frequency of the handover is less than the reference frequency, the frequency selector selects the carrier frequency for systematic-bit mapping from among carrier frequencies to which the systematic bits are mapped in the first base station, and when the frequency of the handover is equal to or greater than the reference frequency, the frequency selector alternately selects the carrier frequency for systematic-bit mapping from among carrier frequencies to which the systematic bits are mapped in the first base station and a carrier frequency having an interference level smaller than the threshold in the second base station. ### Claim 7 (depends on 6) The controller according to claim 6, wherein, in a case where no carrier frequency having an interference level smaller than the threshold is present in either one of the first and the second base stations, when the frequency of the handover is smaller than the reference frequency, the frequency selector selects a carrier frequency to which the systematic bit is mapped in the first base station as the carrier frequency for systematic-bit mapping, and when the frequency of the handover is equal to or greater than the reference frequency, the frequency selector alternately selects the carrier frequency for systematic-bit mapping from among carrier frequencies to which the systematic bits are mapped in the first base station and a carrier frequency having an interference level smaller than the threshold in the second base station. ### Claim 8 (depends on 1) The controller according to claim 1, wherein the frequency selector maps neither the systematic-bit nor the parity-bit to the carrier frequency having an interference level larger than the second threshold value which is larger than the threshold value in the second base station. ### Claim 9 A communication system wherein a mobile station and a base station communicate with each other using some carrier frequencies of a frequency band shared with another system and a controller controls a plurality of the base stations, wherein the base station comprises: a frequency selector that selects an unused frequency band not used by the other system in the frequency band, based on an interference level of the frequency band, selects a carrier frequency for systematic-bit mapping from among carrier frequencies each having the interference level lower than a threshold in carrier frequencies of the unused frequency band and selects a carrier frequency for parity-bit mapping from among carrier frequencies other than the carrier frequency for systematic-bit mapping; a controller communicator that transmits to the controller frequency information indicating a carrier frequency having the interference level lower than the threshold, the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping, the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping being selected by the frequency selector, and receives from the controller signal-assignment-information indicating the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping which are assigned by the controller; a control-signal generator that generates a control-signal including the signal-assignment-information during handover; and a transmitter that transmits the control signal to the mobile station, wherein, the controller comprises: a receiver that receives first frequency information from a first base station in communication with the mobile station and second frequency information from a second base station, the first frequency information indicating a carrier frequency having an interference level lower than a threshold in an unused frequency band, a carrier frequency to which a systematic bit is mapped, and a carrier frequency to which a parity bit is mapped, the second frequency information indicating a carrier frequency having an interference level lower than the threshold in carrier frequencies of an unused frequency band, the second base station being a handover destination; the frequency selector that selects a carrier frequency for systematic-bit mapping and a carrier frequency for parity-bit mapping based on the first frequency information and the second frequency information; a signal-assignment-information generator that generates signal assignment information indicating the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping; and a transmitter that transmits the signal assignment information to the first and the second base stations, wherein the mobile station comprises: a receiver that receives the control signal; a turbo coder that performs turbo coding processing on transmission data and outputs a systematic bit and a parity bit; a carrier-mapper that maps the systematic bit to the carrier frequency for systematic-bit mapping and maps the parity bit to the carrier frequency for parity-bit mapping based on the signal-assignment-information contained in the control signal; an orthogonal frequency division multiplexer that generates an OFDM signal by performing orthogonal frequency division multiplexing processing on the systematic bit and the parity bit mapped to the carrier frequencies; and a transmitter that transmits the OFDM signal to the base station. ### Claim 10 (depends on 9) The communication system according to claim 9, wherein the controller further comprises a frequency determiner that determines whether or not frequency of a handover performed between the first and the second base stations is equal to or greater than a reference frequency, and wherein the frequency selector selects the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping based on the first and the second frequency information and the frequency of the handover. ### Claim 11 (depends on 9) The communication system according to claim 9, wherein the controller transmits an indication signal to the base station when the mobile station within a cell of the base station exists in a cell edge, the indication signal indicating transmission of the frequency information, wherein the controller transmits an unnecessity-indicating signal to the base station when the mobile station within a cell of the base station does not exist in a cell edge after the transmission of the indication signal, the unnecessity-indicating signal indicating transmission of frequency information has become unnecessary, and wherein the base station continuously transmits the frequency information to the controller during a period from receiving the indication signal to receiving the unnecessity-indicating signal. ### Claim 12 A handover method by a controller that controls a plurality of base stations each configured to communicate with a mobile station using some carrier frequencies of a frequency band shared with another system, the handover method comprising: receiving first frequency information from a first base station in communication with the mobile station and second frequency information from a second base station, the first frequency information indicating a carrier frequency having an interference level lower than a threshold in an unused frequency band, a carrier frequency to which a systematic bit is mapped, and a carrier frequency to which a parity bit is mapped, the second frequency information indicating a carrier frequency having an interference level lower than the threshold in carrier frequencies of an unused frequency band, the second base station being a handover destination; selecting a carrier frequency for systematic-bit mapping and a carrier frequency for parity-bit mapping based on the first frequency information and the second frequency information; generating signal assignment information indicating the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping; and transmitting the signal assignment information to the first and the second base stations. ### Claim 13 (depends on 12) The handover method according to claim 12, further comprising: determining whether or not frequency of the handover performed between the first and the second base stations is equal to or greater than a reference frequency; and selecting the carrier frequency for systematic-bit mapping and the carrier frequency for parity-bit mapping based on the first and the second frequency information and the frequency of the handover.