This is the safest method for bulk upgrades.
Understanding Cisco's naming convention is critical to avoiding installation errors that can temporarily brick or corrupt the access point's internal flash memory: AP 3702i - IOS version for Autonomous Mode Ap3g2-k9w7-tar.153-3.jbb1.tar WORK
ap# show version | inc IOS Cisco IOS Software, C3700 Software (ap3g2-k9w7-mx), Version 15.3(3)JBB1 This is the safest method for bulk upgrades
The bootloader on some AP models (especially lightweight APs) supports: C3700 Software (ap3g2-k9w7-mx)