# US 9,521,629 B2 · Transmit power control method of terminal in direct communication between terminals, and terminal supporting the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,629 B2 - Document ID: US9521629B2 - Status: Granted - Kind: B2 - Application number: 14/557,143 - Filed: 2014-12-01 - Published: 2015-06-04 - Granted: 2016-12-13 - Earliest claimed: 2013-12-02 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Taesoo Kwon; Ji Hyung Kim; Moon-Sik Lee - Web page: https://patentgrep.com/patent/US9521629B2 ## CPC - H04W 52/242: {taking into account path loss} - H04W 4/70: Services for machine-to-machine communication [M2M] or machine type communication [MTC] - H04W 52/16: Deriving transmission power values from another channel - H04W 52/46: in multi-hop networks, e.g. wireless relay networks - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A transmit power control method of a terminal in direct communication between terminals is disclosed. The terminal measures a path loss gain of a base station, and compares the measured path loss gain with a predetermined threshold value. The terminal sets a power value for direct communication in the case in which the measured path loss gain is less than or equal to the predetermined threshold value, and performs the direct communication at the set power value. ## Claims ### Claim 1 A method of setting transmit power by a first terminal performing direct communication with a counterpart terminal, the method comprising: measuring a first channel gain which is a path loss gain between a base station to which the first terminal belongs and the first terminal; comparing the first channel gain with a predetermined threshold value; setting a first power value for the direct communication in the case in which the first channel gain is less than or equal to the threshold value; and performing the direct communication at the first power value. ### Claim 2 (depends on 1) The method of claim 1, further comprising not performing the direct communication in the case in which the first channel gain is larger than the threshold value. ### Claim 3 (depends on 1) The method of claim 1, wherein the setting of the first power value includes setting the first power value by considering a second channel gain which is a path loss gain between the counterpart terminal and the first terminal, and the first channel gain. ### Claim 4 (depends on 3) The method of claim 3, further comprising receiving first and second power control factors from the base station, wherein the first power value is set by a value obtained by multiplying the first channel gain by the first power control factor and a value obtained by multiplying the second channel gain by the second power control factor. ### Claim 5 (depends on 4) The method of claim 4, wherein the base station sets the first power control factor using a reverse cellular signal which is received from a terminal performing cellular communication with the base station, and sets the second power control factor using reference signals which are received from the first terminal and the counterpart terminal. ### Claim 6 (depends on 3) The method of claim 3, wherein the first terminal calculates the second channel gain using a reference signal which is received from the counterpart terminal. ### Claim 7 (depends on 1) The method of claim 1, wherein the measuring of the first channel gain includes: receiving a reference signal from the base station; and measuring the reference signal and calculating the first channel gain. ### Claim 8 (depends on 1) The method of claim 1, wherein a resource for the direct communication is overlapped with a resource which is used for cellular communication performed by the base station. ### Claim 9 A terminal comprising: a radio frequency (RF) module receiving a reference signal from a base station; and a processor measuring a first channel gain which is a path loss gain with the base station using the reference signal and controlling direct communication with a counterpart terminal, wherein the processor includes a power setting module comparing the first channel gain with a predetermined threshold value and setting a first power value for the direct communication in the case in which the first channel gain is less than or equal to the threshold value. ### Claim 10 (depends on 9) The terminal of claim 9, wherein the power setting module sets a power value so as to not perform the direct communication in the case in which the first channel gain is larger than the threshold value. ### Claim 11 (depends on 9) The terminal of claim 9, wherein the power setting module sets the first power value by considering a second channel gain which is a path loss gain between the counterpart terminal and the terminal, and the first channel gain. ### Claim 12 (depends on 11) The terminal of claim 11, wherein the RF module receives first and second power control factors from the base station, and the power setting module sets the first power value so as to correspond to a value obtained by multiplying the first channel gain by the first power control factor and a value obtained by multiplying the second channel gain by the second power control factor. ### Claim 13 (depends on 12) The terminal of claim 12, wherein the base station sets the first power control factor using a reverse cellular signal which is received from a terminal performing cellular communication with the base station, and sets the second power control factor using reference signals which are received from the terminal and the counterpart terminal. ### Claim 14 (depends on 9) The terminal of claim 9, wherein a resource for the direct communication is overlapped with a resource which is used for cellular communication performed by the base station.