# US 2018/0026899 A1 · Method and apparatus for controlling send buffer of transmission control protocol in communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026899 A1 - Document ID: US20180026899A1 - Status: Published application - Kind: A1 - Application number: 15/656,466 - Filed: 2017-07-21 - Published: 2018-01-25 - Earliest claimed: 2016-07-21 - Assignees: The Regents of the University of Colorado, a body corporate - Applicants: Samsung Electronics Co., Ltd. - Inventors: Jin-Sung LEE; Young-Bin IM; Sangtae HA; Sang-Jun MOON; Jung-Shin PARK; Ji-Cheol LEE; Joo-Hyung LEE - Web page: https://patentgrep.com/patent/US20180026899A1 ## CPC - H04L 47/283: in response to processing delays, e.g. caused by jitter or round trip time [RTT] - H04L 43/0864: Round trip delays - H04L 47/27: Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets - H04L 43/16: Threshold monitoring - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Methods and apparatuses for controlling transmission control protocol (TCP) send buffers in communication systems are provided. The method includes identifying a current round-trip time (RTT) value and a minimum RTT value in the TCP and adjusting a size of the send buffer based on at least one of a current operation, the current RTT value, and the minimum RTT value in a congestion control scheme according to the TCP. ## Claims ### Claim 1 A method for controlling a send buffer of a transmission control protocol (TCP) in a communication system, the method comprising: identifying a current round-trip time (RTT) value and a minimum RTT value in the TCP; and adjusting a size of the send buffer based on at least one of a current operation, the current RTT value, and the minimum RTT value in a congestion control scheme according to the TCP. ### Claim 2 (depends on 1) The method of claim 1, wherein the adjusting of the size of the send buffer includes, if the current operation corresponds to a slow start operation, adjusting the size of the send buffer by multiplying a size of a congestion window with a predetermined constant. ### Claim 3 (depends on 1) The method of claim 1, wherein the adjusting of the size of the send buffer includes, if the current operation corresponds to a congestion avoidance operation, adjusting the size of the send buffer based on a difference between the current RTT value and the minimum RTT value. ### Claim 4 (depends on 3) The method of claim 3, wherein the adjusting of the size of the send buffer comprises: if the current RTT value is less than a first threshold, increasing the size of the send buffer by a predetermined value; if the current RTT value is a value between the first threshold and a second threshold, maintaining the size of the send buffer; and if the current RTT value is greater than the second threshold, decreasing the size of the send buffer by a multiple of a predetermined value. ### Claim 5 (depends on 4) The method of claim 4, wherein the first threshold and the second threshold are determined based on the minimum RTT value, and wherein the second threshold is greater than the first threshold. ### Claim 6 A method for controlling a send buffer of a transmission control protocol (TCP) in a communication system, the method comprising: if a normal response signal or a TCP acknowledgment is to be transmitted to an opposite device, determining a current operation in a congestion control scheme according to the TCP based on a round-trip time (RTT) value; determining a size of a congestion window based on a data packet received from the opposite device; identifying a current RTT value and a minimum RTT value in the TCP; and adjusting a size of a window to be transmitted to the opposite device based on at least one of the current operation, the size of the congestion window, the current RTT value, and the minimum RTT value. ### Claim 7 (depends on 6) The method of claim 6, wherein the determining of the current operation comprises, if a normal response signal is to be transmitted to the opposite device, determining the current operation based on a comparison between a length of a packet train received within one round from the opposite device and half of the minimum RTT value. ### Claim 8 (depends on 6) The method of claim 6, wherein the determining of the current operation comprises determining the current operation based on a difference between a RTT value that is calculated using a predetermined number of normal response signals included in a data packet received from the opposite device within a current round and a RTT value calculated within a previous round. ### Claim 9 (depends on 6) The method of claim 6, wherein the determining of the size of the congestion window comprises determining a size of a congestion window of the opposite device by dividing a total size of data packets received from the opposite device by a maximum segment size (MSS), and wherein the size of the congestion window is a unit of packet count. ### Claim 10 (depends on 6) The method of claim 6, wherein the adjusting of the size of the window to be transmitted to the opposite device comprises, if the current operation corresponds to a slow start operation, multiplying the size of the congestion window with a predetermined constant. ### Claim 11 (depends on 6) The method of claim 6, wherein the adjusting of the size of the window to be transmitted to the opposite device comprises, if the current operation corresponds to a congestion avoidance operation, determining a difference between the current RTT value and the minimum RTT value. ### Claim 12 (depends on 11) The method of claim 11, wherein the adjusting of the size of the window to be transmitted to the opposite device comprises: if the current RTT value is less than a first threshold, increasing the size of the window to be transmitted to the opposite device by a predetermined value; if the current RTT value between the first threshold and a second threshold, maintaining the size of the window to be transmitted to the opposite device; and if the current RTT value is greater than the second threshold, decreasing the size of the window to be transmitted to the opposite device by a multiple of a predetermined value. ### Claim 13 (depends on 12) The method of claim 12, wherein the first threshold and the second threshold are determined based on the minimum RTT value, and wherein the second threshold is greater than the first threshold. ### Claim 14 An apparatus for controlling a send buffer of a transmission control protocol (TCP) in a communication system, the apparatus comprising: a transceiver configured to transmit and receive data packets; and a controller configured to: identify a current round-trip time (RTT) value and a minimum RTT value in the TCP, and adjust a size of the send buffer based on at least one of a current operation, the current RTT value, and the minimum RTT value in a congestion control scheme according to the TCP. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the processor is further configured to, if the current operation corresponds to a slow start operation, adjust the size of the send buffer by multiplying a size of a congestion window with a predetermined constant. ### Claim 16 (depends on 14) The apparatus of claim 14, wherein the processor is further configured to, if the current operation corresponds to a congestion avoidance operation, adjust the size of the send buffer based on a difference between the current RTT value and the minimum RTT value. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the processor is further configured to: if the current RTT value is less than a first threshold, increase the size of the send buffer by a predetermined constant or additively, if the current RTT value is a value between the first threshold and a second threshold, maintain the size of the send buffer, and if the current RTT value is larger than the second threshold, decrease the size of the send buffer by a multiple of a predetermined value or multiplicatively. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the first threshold and the second threshold are determined based on the minimum RTT value, and wherein the second threshold is greater than the first threshold. ### Claim 19 An apparatus for controlling a send buffer of a transmission control protocol (TCP) in a communication system, the apparatus comprising: a transceiver configured to transmit and receive data packets; and a processor configured to: if a normal response signal or a TCP acknowledgment is to be transmitted to an opposite device, determine a current operation in a congestion control scheme according to the TCP based on a round-trip time (RTT) value, determine a size of a congestion window based on a data packet received from the opposite device, identify a current RTT value and a minimum RTT value in the TCP, and adjust a size of a window to be transmitted to the opposite device based on at least one of the current operation, the size of the congestion window, the current RTT value, and the minimum RTT value. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the processor is further configured to, if the normal response signal is to be transmitted to the opposite device, determine the current operation based on a comparison between a length of a packet train received within one round from the opposite device through the transceiver and a half of the minimum RTT value.