Baseband Processor
Encyclopedia
A baseband processor is a device (a chip or a part of a chip) in a smartphone that manages all the radio functions (all functions that require an antenna). This may not include wi-fi
and/or bluetooth
. It typically uses its own RAM and firmware.
The rationale of separating the baseband processor from the main processor (known as the AP or Application Processor) is threefold:
Baseband processor typically run a RTOS
written in firmware:
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
and/or bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
. It typically uses its own RAM and firmware.
The rationale of separating the baseband processor from the main processor (known as the AP or Application Processor) is threefold:
- radio performance: radio control functions (signal modulation, encoding, radio frequency shifting, etc.) are highly timing dependant, and require a realtime OS
- legal: some authorities (e.g. the U.S. Federal Communications CommissionFederal Communications CommissionThe Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC)) require that the entire software stack running on a device which communicates with the cellular network must be certified. Separating the BP into a different component allows reusing them without having to certify the full AP. - radio reliability: Separating the BP into a different component ensures proper radio operation while allowing application and OS changes.
Baseband processor typically run a RTOS
Real-time operating system
A real-time operating system is an operating system intended to serve real-time application requests.A key characteristic of a RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter...
written in firmware:
- Nucleus RTOSNucleus RTOSNucleus OS is a real-time operating system and toolset created by the Embedded Systems Division of Mentor Graphics for various central processing unit platforms. Nucleus OS is an embedded software solution and is in an estimated 2.11 billion devices worldwide.Development is typically done on a...
(iPhone 3G/3GS/iPad) - ENEAENEA ABENEA is global information technology company with its headquarters in Kista, Sweden that provides real-time operating systems and consulting services...
's OSEOperating System EmbeddedThe Operating System Embedded is a real-time embedded operating system created by the Swedish information technology company ENEA AB. Bengt Eliasson, who at the time was a consultant from ENEA with an assignment at Ericsson, wrote the basic parts of the kernel... - VRTXVersatile Real-Time ExecutiveVersatile Real-Time Executive is a real-time operating system nowadays developed and marketed by the company Mentor Graphics. VRTX is suitable for both traditional board-based embedded systems and SoC architectures....
- ThreadXThreadXThreadX, developed and marketed by Express Logic, Inc. of San Diego, California, USA, is a real-time operating system . Similar RTOSes are available from other vendors such as VxWorks, Nucleus RTOS, OSE, QNX, LynxOS, etc...
(iPhone 4)
Further reading
- Baseband Processor entry at openezx.org
- Babin, Steve. Developing software for Symbian OS: A beginner's guide to creating Symbian OS v9 smartphone applications in C++. Symbian Press, 2007, p. 80.