# US 2018/0026898 A1 · Method and apparatus for controlling congestion 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 2018/0026898 A1 - Document ID: US20180026898A1 - Status: Published application - Kind: A1 - Application number: 15/547,470 - Filed: 2016-01-28 - Published: 2018-01-25 - Earliest claimed: 2015-01-28 - Assignees: Samsung Electronics Co., Ltd.; Unist (Ulsan National Institute of Science and Technology) - Applicants: Samsung Electronics Co., Ltd.; Unist(Ulsan National Institute of Science and Technology) - Inventors: Jin-Sung Lee; Kyunghan Lee; Jung-Shin Park; Han-Na Lim; Joo-Hyung Lee - Web page: https://patentgrep.com/patent/US20180026898A1 ## CPC - H04W 28/0273: {adapting protocols for flow control or congestion control to wireless environment, e.g. adapting transmission control protocol [TCP] (wireless network protocols or protocol adaptations to wireless operation, e.g. wireless application protocol H04W80/00)} - H04L 47/10: Flow control; Congestion control - H04L 47/11: Identifying congestion - H04L 47/12: Avoiding congestion; Recovering from congestion - H04L 47/193: at the transport layer, e.g. TCP related - H04L 47/25: with rate being modified by the source upon detecting a change of network conditions - H04L 47/27: Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets - H04L 47/283: in response to processing delays, e.g. caused by jitter or round trip time [RTT] - H04L 47/29: {using a combination of thresholds} - H04W 28/0236: {radio quality, e.g. interference, losses or delay} - H04W 28/0247: {based on conditions of the access network or the infrastructure network (central resource management H04W28/16)} - H04W 28/0284: {detecting congestion or overload during communication (monitoring arrangements H04L43/00)} - H04W 28/0289: {Congestion control (load shedding arrangements in network planning H04W16/08; performing reselection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12)} - 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 a 5G or a pre-5G communication system for supporting a higher data transmission rate than a 4G communication system such as LTE. A method for controlling TCP congestion in a communication system provided in the present disclosure comprises the steps of: determining the maximum transmission rate of a network, while increasing the size of a congestion window at a predetermined time interval; determining a threshold transmission rate which is determined by a preset ratio with regard to the determined maximum transmission rate; and adjusting the size of the congestion window such that the current transmission rate is not less than the threshold transmission rate and the delay time is no longer than the maximum allowable delay time. ## Claims ### Claim 1 A method for controlling transmission control protocol (TCP) congestion in a communication system, the method comprising: determining a maximum transmission rate of a network while increasing a congestion window size every predetermined time unit; determining a threshold transmission rate to be a predetermined ratio of the determined maximum transmission rate; and adjusting the congestion window size such that a current transmission rate is greater than or equal to the threshold transmission rate and a delay time is less than or equal to a maximum allowable delay time. ### Claim 2 (depends on 1) The method of claim 1, wherein the maximum transmission rate is determined to be a greater value between a transmission rate at a current point in time and a transmission rate until a previous point in time. ### Claim 3 (depends on 1) The method of claim 1, wherein the threshold transmission rate is set considering the delay time. ### Claim 4 (depends on 1) The method of claim 1, wherein the adjusting of the congestion window size comprises: increasing the congestion window size from a previous congestion window size, if a value is positive; and reducing the congestion window size from the previous congestion window size, if the value is not positive, wherein E(i) is 1−(current transmission rate/threshold transmission rate) at a point in time i, wherein intE(i) is an integral value of E(i) or (1−λ)*intE(i−1)+λ*E(i), and wherein λ is a moving average weight value, wherein a rate for increasing the congestion window size when the value is positive is set greater than a rate for reducing the congestion window size when the value is not positive. ### Claim 5 (canceled) ### Claim 6 (depends on 1) The method of claim 1, wherein the adjusting of the congestion window size comprises: increasing the congestion window size from a previous congestion window size, if E(i) is positive; and reducing the congestion window size from the previous congestion window size, if E(i) is not positive, wherein E(i) is 1−(current transmission rate/threshold transmission rate) at a point in time i. ### Claim 7 (depends on 6) The method of claim 6, wherein a rate for increasing the congestion window size when E(i) is positive is set greater than a rate for reducing the congestion window size when E(i) is not positive. ### Claim 8 (depends on 1) The method of claim 1, further comprising if a state of the network changes, determining at least one of the maximum transmission rate and the threshold transmission rate according to the state of the network. ### Claim 9 (depends on 8) The method of claim 8, wherein whether the state of the network changes is determined by comparing the current transmission rate with the threshold transmission rate. ### Claim 10 (depends on 9) The method of claim 9, wherein it is determined that the state of the network changes, if the current transmission rate is maintained as being greater than the threshold transmission rate for a predetermined time or if the current transmission rate is maintained as being less than the threshold transmission rate for the predetermined time, wherein if the current transmission rate is maintained as being greater than the threshold transmission rate for the predetermined time, further comprising: determining the maximum transmission rate, determining the threshold transmission rate based on the determined maximum transmission rate, and adjusting the congestion window size, wherein if the current transmission rate is maintained as being less than the threshold transmission rate for the predetermined time, further comprising: resetting the threshold transmission rate to a current transmission rate that is maintained as being less than the threshold transmission rate for the predetermined time. ### Claim 11 (canceled) ### Claim 12 (canceled) ### Claim 13 (depends on 1) The method of claim 1, further comprising: receiving information of a reception congestion window size determined by a receiver; and determining a final congestion window size using the received information of the reception congestion window size and the determined congestion window size. ### Claim 14 An apparatus for controlling transmission control protocol (TCP) congestion in a communication system, the apparatus comprising: a transmission rate controller configured to determine a maximum transmission rate of a network while increasing a congestion window size every predetermined time unit and to determine a threshold transmission rate to be a predetermined ratio of the determined maximum transmission rate; and a window controller configured to adjust the congestion window size such that a current transmission rate is greater than or equal to the threshold transmission rate and a delay time is less than or equal to a maximum allowable delay time. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the maximum transmission rate is determined to be a greater value between a transmission rate at a current point in time and a maximum transmission rate until a previous point in time. ### Claim 16 (depends on 14) The apparatus of claim 14, wherein the threshold transmission rate is set considering the delay time. ### Claim 17 (depends on 14) The apparatus of claim 14, wherein the window controller is configured to increase the congestion window size from a previous congestion window size, if a value is positive and reduce the congestion window size from the previous congestion window size, if the value is not positive, wherein E(i) is 1−(current transmission rate/threshold transmission rate) at a point in time i, wherein intE(i) is an integral value of E(i) or (1−λ)*intE(i−1)+λ*E(i), and wherein λ is a moving average weight value, wherein a rate for increasing the congestion window size when the value is positive is set greater than a rate for reducing the congestion window size when the value is not positive. ### Claim 18 (depends on 14) The apparatus of claim 14, the window controller is configured to increase the congestion window size from a previous congestion window size, if E(i) is positive and reduce the congestion window size from the previous congestion window size, if E(i) is not positive, wherein E(i) is 1−(current transmission rate/threshold transmission rate) at a point in time i. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein a rate for increasing the congestion window size when E(i) is positive is set greater than a rate for reducing the congestion window size when E(i) is not positive. ### Claim 20 (depends on 14) The apparatus of claim 14, if a state of the network changes, the transmission rate controller is configured to determine at least one of the maximum transmission rate and the threshold transmission rate according to the state of the network. ### Claim 21 (depends on 20) The apparatus of claim 20, wherein whether the state of the network changes is determined by comparing the current transmission rate with the threshold transmission rate. ### Claim 22 (depends on 21) The apparatus of claim 21, wherein it is determined that the state of the network changes if the current transmission rate is maintained as being greater than the threshold transmission rate for a predetermined time or if the current transmission rate is maintained as being less than the threshold transmission rate for the predetermined time, wherein if the current transmission rate is maintained as being greater than the threshold transmission rate for the predetermined time, the transmission rate controller is configured to determine the maximum transmission rate and determine the threshold transmission rate based on the determined maximum transmission rate and the window controller is configured to adjust the congestion window size again, and wherein if the current transmission rate is maintained as being less than the threshold transmission rate for the predetermined time, the transmission rate controller is configured to reset the threshold transmission rate to the current transmission rate that is maintained as being less than the threshold transmission rate for the predetermined time. ### Claim 23 (depends on 14) The apparatus of claim 14, further comprising: a receiver configured to receive information of a reception congestion window size determined by second receiver, wherein the window controller is configured to determine a final congestion window size using the received information of the reception congestion window size and the determined congestion window size.