Baseband processor

<h2 id="overview">Overview</h2>
<p>Baseband processors typically run a <a href="/facts/Real-time_operating_system/IvUCFwCL">real-time operating system</a> (RTOS) as their firmware, such as <a href="/facts/ENEA_AB/ND2jhhsU">ENEA</a>'s <a href="/facts/Operating_System_Embedded/ND2jhhsU">OSE</a>, <a href="/facts/Nucleus_RTOS/ThngFw3k">Nucleus RTOS</a> (iPhone 3G/3GS/iPad), <a href="/facts/ThreadX/WrRGsNVz">ThreadX</a> (iPhone 4), and <a href="/facts/Versatile_Real-Time_Executive/SHjIyLMC">VRTX</a>.  There are more than a few significant manufacturers of baseband processors, including <a href="/facts/Broadcom/pbh0q7ht">Broadcom</a>, <a href="/facts/Icera/FLXNq5ko">Icera</a>, <a href="/facts/Intel_Mobile_Communications/0PVX1lWX">Intel Mobile Communications</a> (former Infineon wireless division), <a href="/facts/MediaTek/X0yoLa9D">MediaTek</a>, <a href="/facts/Qualcomm/v54S3UgA">Qualcomm</a>,  <a href="/facts/Spreadtrum/QkDjtLam">Spreadtrum</a>, and <a href="/facts/ST-Ericsson/T6V8shaS">ST-Ericsson</a>.
</p><p>The rationale of separating the baseband processor from the main processor (known as the <i>application processor</i> or AP or) is threefold:
</p>
Radio performance
Radio control functions (signal modulation, encoding, radio frequency shifting, etc.) are highly timing-dependent, and require a real-time operating system.
Radio reliability
Separating the BP into a different component ensures proper radio operation while allowing application and OS changes.
Legal
Some authorities (e.g. the U.S. <a href="/facts/Federal_Communications_Commission/Ueghz8W0">Federal Communications Commission</a> (FCC)) require that the entire software stack running on a device which communicates with the <a href="/facts/Mobile_telephony/pFqFCDyl">mobile telephony</a> network must be certified. Separating the BP into a different component allows reusing a stack without having to recertify the full AP.
<h2 id="security-concerns">Security concerns</h2>
<p class="note">See also: <a href="/facts/List_of_open-source_mobile_phones/bCzFFaTc">List of open-source mobile phones § Scope of the list</a></p>
<p>Since the software which runs on baseband processors is usually proprietary, it is impossible to perform an independent code audit. By <a href="/facts/Reverse_engineering/pmJCV7J7">reverse engineering</a> some of the baseband chips, researchers have found security vulnerabilities that could be used to access and modify data on the phone remotely.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> In March 2014, makers of the free <a href="/facts/Android_(operating_system)/nNyHb0xz">Android</a> derivative <a href="/facts/Replicant_(operating_system)/dpgSbIpG">Replicant</a> announced they had found a <a href="/facts/Backdoor_(computing)/4Vry8CKE">backdoor</a> in the baseband software of <a href="/facts/Samsung/oNXUwDjn">Samsung</a> Galaxy phones that allows remote access to the user data stored on the phone.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/OsmocomBB/pArh0neg">OsmocomBB</a> - <a href="/facts/Free_software/IaoVtJXn">free software</a> for baseband processors</li></ul>

<h2 id="further-reading">Further reading</h2>
<ul><li><a href="https://web.archive.org/web/20130501065823/http://wiki.openezx.org/BP">Baseband Processor entry</a> at openezx.org, archived from the original on May 5, 2013</li>
<li>Babin, Steve. <a href="https://books.google.com/books?id=thd5DSWn_F4C&pg=PA80"><i>Developing software for Symbian OS: A beginner's guide to creating Symbian OS v9 smartphone applications in C++</i></a>. Symbian Press, 2007, p. 80.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Chen, Wai-Kai (2018). The VLSI Handbook. CRC Press. pp. 60–2. ISBN 9781420005967. <a href="9781420005967" target="_blank">9781420005967</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Morgado, Alonso; Río, Rocío del; Rosa, José M. de la (2011). Nanometer CMOS Sigma-Delta Modulators for Software Defined Radio. Springer Science & Business Media. p. 1. ISBN 9781461400370. <a href="9781461400370" target="_blank">9781461400370</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Ralf Philipp Weinmann (10 May 2012). "DeepSec 2010: All your baseband are belong to us". YouTube. Retrieved 2014-03-15. <a href="https://www.youtube.com/watch?v=fQqv0v14KKY" target="_blank">https://www.youtube.com/watch?v=fQqv0v14KKY</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Ralf Philipp Weinmann. "WOOT 2012: Baseband Attacks: Remote Exploitation of Memory Corruptions in Cellular Protocol Stacks" (PDF). USENIX WOOT. Retrieved 2015-04-05. <a href="https://www.usenix.org/system/files/conference/woot12/woot12-final24.pdf" target="_blank">https://www.usenix.org/system/files/conference/woot12/woot12-final24.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Replicant developers find and close Samsung Galaxy backdoor". Free Software Foundation. Retrieved 2015-10-03. <a href="https://www.fsf.org/blogs/community/replicant-developers-find-and-close-samsung-galaxy-backdoor" target="_blank">https://www.fsf.org/blogs/community/replicant-developers-find-and-close-samsung-galaxy-backdoor</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Baseband processor open-in-new

Baseband processor