# US 2014/0153440 A1 · Systems and methods for syncrhonization of wireless devices in an ad-hoc network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153440 A1 - Document ID: US20140153440A1 - Status: Published application - Kind: A1 - Application number: 13/835,788 - Filed: 2013-03-15 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: QUALCOMM Incorporated - Applicants: Qualcomm Incorporated - Inventors: Yan Zhou; George Cherian; Santosh Paul Abraham - Web page: https://patentgrep.com/patent/US20140153440A1 ## CPC - H04W 56/0015: {one node acting as a reference for the others} - H04L 45/28: using route fault recovery - H04W 40/005: {Routing actions in the presence of nodes in sleep or doze mode} - H04W 40/12: based on transmission quality or channel quality - H04W 40/20: based on geographic position or location - H04W 40/22: using selective relaying for reaching a BTS [Base Transceiver Station] or an access point - H04W 40/246: {Connectivity information discovery} - H04W 84/18: Self-organising networks, e.g. ad-hoc networks or sensor networks - H04W 84/20: Leader-follower arrangements - Y02D 30/70: in wireless communication networks - 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) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract Methods, devices, and computer program products for synchronization of wireless devices in an ad-hoc network are described herein. In one aspect, a method for synchronizing a wireless communication apparatus is provided. The method includes generating, at a wireless communication apparatus, one or more messages identifying a second device to generate prospective synchronization messages. In some aspects, the second device is a back-up root device. The method further includes transmitting a synchronization message. In one aspect, a root device for an ad-hoc network is responsible for generating synchronization messages for nodes of the ad-hoc network. The root device also generates and transmits a message which identifies a back-up root device. The back-up root device may assume responsibility for generating synchronization messages for the ad-hoc network in the event that the wireless communication apparatus no longer generates synchronization messages for the ad-hoc network. In an embodiment, the generated message identifying the back-up root device is included in a synchronization message. ## Claims ### Claim 1 A method for wireless communication performed by a root device within an ad-hoc network, comprising: generating a message, the message identifying a second device to generate prospective synchronization messages; and transmitting a synchronization message. ### Claim 2 (depends on 1) The method of claim 1, further comprising transmitting the generated message. ### Claim 3 (depends on 2) The method of claim 2, wherein the generated message is included in the synchronization message. ### Claim 4 (depends on 1) The method of claim 1, wherein a plurality of devices communicate over the ad-hoc network during an availability window, and the synchronization message updates an availability window schedule. ### Claim 5 (depends on 1) The method of claim 1, wherein the synchronization message includes clock reference information. ### Claim 6 (depends on 1) The method of claim 1, wherein the synchronization message is retransmitted by a portion of the plurality of devices. ### Claim 7 (depends on 2) The method of claim 2, further comprising determining that the device is leaving the ad-hoc network, wherein the generated message is transmitted in response to the determining. ### Claim 8 (depends on 2) The method of claim 2, wherein the transmitted message identifies the second device as a back-up root device for the ad-hoc network. ### Claim 9 (depends on 1) The method of claim 1, further comprising receiving a synchronization message identifying the device by a non-root device. ### Claim 10 (depends on 1) The method of claim 1, further comprising determining the second device based on a received signal strength indication. ### Claim 11 (depends on 1) The method of claim 1, further comprising determining the second device based on a path loss between the second device and the device. ### Claim 12 (depends on 9) The method of claim 9, further comprising retransmitting the received message by the non-root device. ### Claim 13 (depends on 1) The method of claim 1, further comprising determining the second device periodically. ### Claim 14 A root device for wireless communication within an ad-hoc network, comprising: a processor configured to generate a message, the message identifying a second device to generate prospective synchronization messages; and a transmitter configured to transmit a synchronization message. ### Claim 15 (depends on 14) The device of claim 14, further comprising transmitting the generated message. ### Claim 16 (depends on 15) The device of claim 15, wherein the generated message is included in the synchronization message. ### Claim 17 (depends on 14) The root device of claim 14, wherein a plurality of devices communicate over the ad-hoc network during an availability window, and the synchronization message updates an availability window schedule. ### Claim 18 (depends on 17) The root device of claim 17, wherein the synchronization message includes clock reference information. ### Claim 19 (depends on 17) The root device of claim 17, wherein the synchronization message is retransmitted by a portion of the plurality of devices. ### Claim 20 (depends on 17) The root device of claim 17, wherein the processor is further configured to determine that the root device is leaving the ad-hoc network, wherein the generated message is transmitted in response to the determining. ### Claim 21 (depends on 15) The root device of claim 15, wherein the transmitted message identifies the second device as a back-up root device for the ad-hoc network. ### Claim 22 (depends on 14) The root device of claim 14, further comprising a receiver configured to receive a synchronization message identifying the device. ### Claim 23 (depends on 14) The root device of claim 14, wherein the processor is further configured to determine the second device based on a received signal strength indication. ### Claim 24 (depends on 14) The root device of claim 14, wherein the processor is further configured to determine the second device based on a path loss between the second device and the device. ### Claim 25 (depends on 22) The root device of claim 22, wherein the transmitter is further configured to retransmit the received message. ### Claim 26 (depends on 14) The device of claim 14, wherein the processor is further configured to determine the second device periodically. ### Claim 27 A root device for wireless communication within an ad-hoc network, comprising: means for generating a message, the message identifying a second device to generate prospective synchronization messages; and means for transmitting a synchronization message. ### Claim 28 (depends on 27) The root device of claim 27, further comprising means for transmitting the generated message. ### Claim 29 (depends on 28) The root device of claim 28, wherein the generated message is included in the synchronization message. ### Claim 30 (depends on 27) The root device of claim 27, wherein a plurality of devices communicate over the ad-hoc network during an availability window, and the synchronization message updates an availability window schedule. ### Claim 31 (depends on 30) The root device of claim 30, wherein the synchronization message includes clock reference information. ### Claim 32 (depends on 30) The root device of claim 30, wherein the synchronization message is retransmitted by a portion of the plurality of devices. ### Claim 33 (depends on 28) The root device of claim 28, further comprising means for determining that the device is leaving the ad-hoc network, wherein the generated message is transmitted in response to the determining. ### Claim 34 (depends on 28) The root device of claim 28, wherein the transmitted message identifies the second device as a back-up root device for the ad-hoc network. ### Claim 35 (depends on 27) The root device of claim 27, further comprising means for receiving a synchronization message identifying the device. ### Claim 36 (depends on 27) The root device of claim 27, further comprising means for determining the second device based on a received signal strength indication. ### Claim 37 (depends on 27) The root device of claim 27, further comprising means for determining the second device based on a path loss between the second device and the device. ### Claim 38 (depends on 35) The root device of claim 35, further comprising means for retransmitting the received message. ### Claim 39 (depends on 27) The root device of claim 27, further comprising means for determining the second device periodically. ### Claim 40 A non-transitory, computer readable medium comprising instructions that when executed cause a processor in a root device to perform a method for wireless communication within an ad-hoc network, the method comprising: generating a message, the message identifying a second device to generate prospective synchronization messages; and transmitting a synchronization message. ### Claim 41 (depends on 40) The non-transitory, computer readable medium of claim 40, further comprising transmitting the generated message. ### Claim 42 (depends on 41) The non-transitory, computer readable medium of claim 41, wherein the generated message is included in the synchronization message. ### Claim 43 (depends on 40) The non-transitory, computer readable medium of claim 40, wherein a plurality of devices communicate over the ad-hoc network during an availability window, and the synchronization message updates an availability window schedule. ### Claim 44 (depends on 43) The non-transitory, computer readable medium of claim 43, wherein the synchronization message includes clock reference information. ### Claim 45 (depends on 43) The non-transitory, computer readable medium of claim 43, wherein the synchronization message is retransmitted by a portion of the plurality of devices. ### Claim 46 (depends on 40) The non-transitory, computer readable medium of claim 40, wherein the method further comprises determining that the device is leaving the ad-hoc network, wherein the generated message is transmitted in response to the determining. ### Claim 47 (depends on 41) The non-transitory, computer readable medium of claim 41, wherein the transmitted message identifies the second device as a back-up root device for the ad-hoc network. ### Claim 48 (depends on 40) The non-transitory, computer readable medium of claim 40, the method further comprising receiving a message identifying the device. ### Claim 49 (depends on 40) The non-transitory, computer readable medium of claim 40, the method further comprising determining the second device based on a received signal strength indication. ### Claim 50 (depends on 40) The non-transitory, computer readable medium of claim 40, the method further comprising determining the second device based on a path loss between the second device and the device. ### Claim 51 (depends on 48) The non-transitory, computer readable medium of claim 48, the method further comprising retransmitting the received message. ### Claim 52 (depends on 40) The non-transitory, computer readable medium of claim 40, the method further comprising determining the second device periodically. ### Claim 53 A method of communicating over an ad-hoc wireless network with a device, comprising: receiving a message from a root device, the message indicating a receiving device will generate prospective synchronization messages; determining whether the root device is available; and transmitting a synchronization message based on the determining. ### Claim 54 (depends on 57) The method of claim 57, wherein the received message is a synchronization message. ### Claim 55 (depends on 53) The method of claim 53, wherein determining whether the root node is available comprises determining whether a synchronization message has been received within a predetermined time period. ### Claim 56 (depends on 54) The method of claim 54, wherein determining whether the root node is available comprises determining that the root node will not be available based on receiving the message. ### Claim 57 A non-root device for communicating over an ad-hoc wireless network, comprising: a receiver configured to receive a message from a root device, the message indicating the non-root device will generate prospective synchronization messages; a processor configured to determine whether the root device is available; and a transmitter configured to transmit a synchronization message based on the determining. ### Claim 58 (depends on 57) The non-root device of claim 57, wherein the received message is a synchronization message. ### Claim 59 (depends on 57) The non-root device of claim 57, wherein the processor is configured to determine whether the root node is available by at least in part determining whether a synchronization message has been received within a predetermined time period. ### Claim 60 (depends on 57) The non-root device of claim 57, wherein the processor is configured to determine whether the root node is available at least in part by determining that the root node will not be available based on receiving the message. ### Claim 61 A non-root device for communicating over an ad-hoc wireless network, comprising: means for receiving a message from a root device, the message indicating the non-root device will generate prospective synchronization messages; means for determining whether the root device is available; and means for transmitting a synchronization message based on the determining. ### Claim 62 (depends on 61) The non-root device of claim 61, wherein the received message is a synchronization message. ### Claim 63 (depends on 61) The non-root device of claim 61, wherein the means for determining is configured to determine whether a synchronization message has been received within a predetermined time period. ### Claim 64 (depends on 61) The non-root device of claim 61, wherein the means for determining is configured to determine whether the root node is available at least in part by determining that the root node will not be available based on receiving the message. ### Claim 65 A non-transitory, computer readable medium comprising instructions that when executed cause a processor to perform a method of communicating over an ad-hoc wireless network with a device, the method comprising: receiving a message from a root device, the message indicating a receiving device will generate prospective synchronization messages; determining whether the root device is available; and transmitting a synchronization message based on the determining. ### Claim 66 (depends on 65) The non-transitory, computer readable medium of claim 65, wherein the received message is a synchronization message. ### Claim 67 (depends on 65) The non-transitory, computer readable medium of claim 65, wherein determining whether the root node is available comprises determining whether a synchronization message has been received within a predetermined time period. ### Claim 68 (depends on 65) The non-transitory, computer readable medium of claim 65, wherein determining whether the root node is available comprises determining that the root node will not be available based on receiving the message.