# US 10,321,488 B2 · CSMA/CA in time and frequency domains > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,321,488 B2 - Document ID: US10321488B2 - Status: Granted - Kind: B2 - Application number: 15/604,486 - Filed: 2017-05-24 - Published: 2017-11-30 - Granted: 2019-06-11 - Earliest claimed: 2016-05-27 - Assignees: Ecole Polytechnique Federale De Lausanne (Epfl) - Applicants: Ecole Polytechnique Federale De Lausanne (Epfl) - Inventors: Julien Herzen; Patrick Thiran; Albert Banchs; Vsevolod Shneer - Web page: https://patentgrep.com/patent/US10321488B2 ## CPC - H04W 74/0825: {with collision detection} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract The present invention concerns a method for a communication device to transmit a data packet in a wireless communication system. The method comprises: determining a first set of transmission parameters comprising a first central transmission frequency and a first spectral bandwidth; transmitting a first data packet by applying the first set of transmission parameters; determining whether or not the first data packet collided with a second data packet from a second communication device; determining a second set of transmission parameters, which in case of collision comprises a second central transmission frequency, different from the first central transmission frequency, and a second spectral bandwidth, which is different from the first spectral bandwidth with a first, non-zero probability and the same as the first spectral bandwidth with a second probability; and transmitting a second data packet by applying the second set of transmission parameters. ## Claims ### Claim 1 A method for a first communication device to transmit a data packet in a wireless communication system, the method comprising: determining a first set of transmission parameters comprising a first central transmission frequency and a first spectral bandwidth; transmitting a first data packet by applying the first set of transmission parameters; determining whether or not the first data packet collided with a second data packet from a second communication device; determining a second set of transmission parameters, which in case of collision comprises a second central transmission frequency, and a second spectral bandwidth, which is different from the first spectral bandwidth with a first probability value, and the same as the first spectral bandwidth with a second probability value, the second probability value being equal to 1—the first probability value, the first probability value being non-zero unless the first spectral bandwidth is the minimum spectral bandwidth allowed in the communication system; and transmitting a second data packet by applying the second set of transmission parameters. ### Claim 2 (depends on 1) The method according to claim 1, wherein the second central transmission frequency is different from the first central transmission frequency. ### Claim 3 (depends on 1) The method according to claim 1, wherein the second central transmission frequency is randomly selected from a set of available transmission frequencies. ### Claim 4 (depends on 1) The method according to claim 1, wherein the first probability value depends on the first spectral bandwidth. ### Claim 5 (depends on 1) The method according to claim 1, wherein the first probability value is obtained by dividing the first spectral bandwidth with a maximal spectral bandwidth available to any communication device in the wireless communication system. ### Claim 6 (depends on 1) The method according to claim 1, wherein the second spectral bandwidth is selected to be smaller than the first spectral bandwidth with the first probability value. ### Claim 7 (depends on 1) The method according to claim 1, wherein the second spectral bandwidth is substantially half of the first spectral bandwidth. ### Claim 8 (depends on 1) The method according to claim 1, wherein the method further comprises, before transmitting the second data packet: sensing a transmission medium to determine whether or not the transmission medium is busy; and if the transmission medium is sensed to be busy, then reducing the second spectral bandwidth with a third probability value before sending the second data packet, the third probability value being non-zero unless the second spectral bandwidth is the minimum spectral bandwidth allowed in the communication system. ### Claim 9 (depends on 8) The method according to claim 8, wherein the second spectral bandwidth is reduced by halving it with the third probability. ### Claim 10 (depends on 8) The method according to claim 8, wherein the third probability value is between 0.005 and 0.05. ### Claim 11 (depends on 1) The method according to claim 1, wherein the first and/or second set of transmission parameters also comprise(s) time domain parameters for defining a time domain packet transmission operation of the first communication device. ### Claim 12 (depends on 1) The method according to claim 1, wherein the second set of transmission parameters, in case of no collision, comprises: a third spectral bandwidth, which is different from the first spectral bandwidth with a fourth probability value, and the same as the first spectral bandwidth with a fifth probability value, the fifth probability value being equal to 1—the fourth probability value, the fourth probability value being non-zero unless the first spectral bandwidth is the largest spectral bandwidth allowed in the communication system, and a third central transmission frequency, which is different from the first central transmission frequency if the third spectral bandwidth is different from the first spectral bandwidth and the same as the first central transmission frequency if the third spectral bandwidth is the same as the first spectral bandwidth. ### Claim 13 (depends on 12) The method according to claim 12, wherein the third spectral bandwidth is selected to be larger than the first spectral bandwidth with the fourth probability. ### Claim 14 (depends on 12) The method according to claim 12, wherein the third spectral bandwidth is substantially twice the first spectral bandwidth. ### Claim 15 (depends on 12) The method according to claim 12, wherein the third central transmission frequency is selected to be a central transmission frequency adjacent to the first central transmission frequency if the third spectral bandwidth is different from the first spectral bandwidth. ### Claim 16 (depends on 12) The method according to claim 12, wherein the fourth probability is between 0.0005 and 0.005. ### Claim 17 (depends on 1) The method according to claim 1, wherein the first set of transmission parameters also comprises a first contention window value, and wherein the second set of transmission parameters, in case of no collision, comprises a second contention window value smaller than the first contention window value. ### Claim 18 A communication device for transmitting a data packet in a wireless communication system, the communication device comprising means for: determining a first set of transmission parameters comprising a first central transmission frequency and a first spectral bandwidth; transmitting a first data packet by applying the first set of transmission parameters; determining whether or not the first data packet collided with a second data packet from a second communication device; determining a second set of transmission parameters, which in case of collision comprises a second central transmission frequency, and a second spectral bandwidth, which is different from the first spectral bandwidth with a first probability value, and the same as the first spectral bandwidth with a second probability value, the second probability value being equal to 1—the first probability value, the first probability value being non-zero unless the first spectral bandwidth is the minimum spectral bandwidth allowed in the communication system; and transmitting a second data packet by applying the second set of transmission parameters. ### Claim 19 (depends on 18) A wireless communication system comprising the communication device according to claim 18, wherein the wireless communication system is a wireless local area network.