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Abaseband processor (also known asbaseband radio processor,BP, orBBP) is adevice (achip or part of a chip) in anetwork interface controller that manages all theradio functions (all functions that require an antenna); however, this term is generally not used in reference toWi-Fi andBluetooth radios. A baseband processor typically uses its ownRAM andfirmware. Baseband processors are typicallyfabricated usingCMOS (complementarymetal–oxide–semiconductor) orRF CMOS technology,[1] and are widely used inradio-frequency (RF),GPS andwireless WAN communications.[2]
Baseband processors typically run areal-time operating system (RTOS) as their firmware, such asENEA'sOSE,Nucleus RTOS (iPhone 3G/3GS/iPad),ThreadX (iPhone 4), andVRTX. There are more than a few significant manufacturers of baseband processors, includingBroadcom,Icera,Intel Mobile Communications (former Infineon wireless division),MediaTek,Qualcomm,Spreadtrum, andST-Ericsson.
The rationale of separating the baseband processor from the main processor (known as theapplication processor or AP or) is threefold:
Since the software which runs on baseband processors is usually proprietary, it is impossible to perform an independent code audit. Byreverse engineering some of the baseband chips, researchers have found security vulnerabilities that could be used to access and modify data on the phone remotely.[3][4] In March 2014, makers of the freeAndroid derivativeReplicant announced they had found abackdoor in the baseband software ofSamsung Galaxy phones that allows remote access to the user data stored on the phone.[5]