New U.S. regulations went into effect today that could change how vendors of devices with software-defined radios (SDR) use open-source software. The new rules could impact manufacturers of mobile phones, WiFi cards, and other devices that use SDR technologies.

SDR technologies are commonly used in today's mobile phones and WiFi equipment. The U.S. Federal Communications Commission's (FCC) new regulations are apparently aimed at ensuring that users of such equipment cannot access source code needed to reprogram it — for example, to output more power, or operate on inappropriate frequencies, either of which could conceivably endanger public safety.

A summary document published by the FCC suggests that the new regulations were actually proposed by Cisco, a vendor of wireless cards and other networking equipment. The summary document suggests that because of the new rules, SDR device vendors who use open-source software in certain capacities could face challenges getting FCC approval.

The FCC's summary report reads, in part:

The Commission hereby states that … manufacturers should not intentionally make the distinctive elements that implement that manufacturer's particular security measures in a software defined radio public, if doing so would increase the risk that these security measures could be defeated or otherwise circumvented to allow operation of the radio in a manner that violates the Commission's rules. A system that is wholly dependent on open source elements will have a high burden to demonstrate that it is sufficiently secure to warrant authorization as a software defined radio.

The Software Freedom Law Center reacted by issuing a whitepaper that seems intended to keep open-source SDR software developers motivated to continue their work. The whitepaper notes that the FCC's authority ends with hardware devices, and maintains that the agency has not enacted any rules intended to regulate software development. “Even if the FCC did have the power to regulate independent software development, it has promulgated no rules governing such activity,” the SFLC's whitepaper reads in part.

Motorola and other vendors of Linux-based mobile phones typically segregate radio software stacks from Linux application stacks by running them on separate physical or virtual processors. A multiplexed serial connection allows the Linux OS to access the network through a limited AT-command-style API, just as if the radio baseband controller were an actual modem. This architecture was designed to keep radio software secure against compromises to the Linux OS, and far enough removed from GPL-licensed software to prevent the GPL's “viral” nature from kicking in.

Some WiFi card vendors, meanwhile — Intel and Broadcom come to mind — take advantage of Linux's “hotplug” feature by writing open Linux drivers that load sensitive radio software microcode from encrypted binary files stored in the users' filesystem. This arrangement seems to be tolerated, if not unanimously appreciated, by the open source community (who, after all, are glad to have use of inexpensive wireless cards).

The FCC's summary report also includes this comment about Linux and open-source software:

The Commission recognizes that some manufacturers may wish to use open source software (e.g., GNU/Linux) in developing SDRs. The use of such software may have advantages for manufacturers such as lower cost and decreased product development time.”

The FCC's 2500-word summary document is here, while the SFLC's whitepaper can be found here.

—Henry Kingman

 
This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.