Mobile Phones: the Embedded Linux Challenge
Although mobile handset manufacturers are embracing Linux as an emerging platform for next-generation smart phones, development and deployment of those devices still face key technical challenges. In particular, mobile phone OEMs must deliver devices with power management, fast boot up, integrated radio (GPRS) interfaces, advanced multimedia capabilities, attractive small form-factor GUIs and differentiated PIM application sets (browser, phone book and so forth)—all integrated and running in a modest memory footprint. This is a particular challenge for embedded Linux developers because, unlike PCs, phones aren't built to a standard architecture.
This article examines various technical challenges that face developers of Linux-based mobile phones. It addresses availability and maturity of key enabling Linux capabilities and also of open-source projects that support phone application development. In addition, it discusses technical and economic challenges presented by the stringent and numerous requirements of mobile network operators.
The global mobile phone market is growing at an explosive pace. Industry analysts at IDC report that in Q2/2005, the handset market grew 34%, as almost 700 million handsets made their way from device OEMs into people's hands and onto the global voice and data networks. Analysts at Gartner predict that by 2009, the global installed base will number more than 2.6 billion mobile phones.
For the Linux-centric segment of the IT industry, these numbers are tantalizing—orders of magnitude greater than total Linux shipments and installed base for servers, and far greater in volume than the worldwide desktop market. As such, the mobile phone market represents both an opportunity to “break out”, reaching significant market share in client devices and to complement the already significant presence of Linux in the communications infrastructure (based on carrier grade and other versions of enterprise and embedded Linux).
In the past few years, Linux has made significant gains as a mobile phone platform OS. Device manufacturers LG, Motorola, NEC, Panasonic and Samsung today ship two-dozen smart phone models based on Linux, complemented by Chinese brands like Datang, e28, Haier, Huawei and ZTE. Nokia and others also are beginning to ship Linux-based wireless VoIP clients.
Device OEMs, large and small, are choosing Linux as the strategic platform for their smart phones for a mix of technical and economic reasons. On the technical side, OEMs look to Linux for performance, robustness, “gold standard” TCP/IP networking (especially routing) and flexibility. On the economic front, Linux offers OEMs lower development and deployment costs, more choice of vendors (including “roll your own”), a larger open and commercial technology ecosystem, and an opportunity to unify the divergent and costly product lines and engineering efforts needed to support multiple product tiers (smart phones, feature phones and entry-level devices), network types (GSM, CDMA, analog and Wi-Fi) and carrier requirements.
For all of these strong technical and economic benefits, Linux phones account today for between 1–2% of the total market. On smart phones, the fastest-growing segment, Linux enjoys a stronger position. Smart phone share is growing at 85% per year, and Linux owns 25% of the smart phone segment (Q2/2005 Gartner), far ahead of Windows Mobile and others, but behind SymbianOS by a factor of two or more.
Categorizing phone types is not an exact science, nor even an exacting marketing exercise. Features that once differentiated phones strongly (like e-mail or imaging) are now commonplace across tiers and price ranges. Moreover, what is smart today may be a common feature in six months. Feature phones for which you pay good money at the holidays can end up as entry-level giveaways toward the end of their market lifetime the following spring and summer.
Table 1. Mobile Phone Market Tiers
|Top Tier “Smart Phone”||$200 US and up||Telephony, often Wi-Fi/VoIP, full e-mail and browsing, multimedia (MP3, video), SMS/MMS, games and voice commands||ARM9, ARM11||SymbianOS, Linux, Windows Mobile, PalmOS, RIM|
|Mid Tier “Feature/Enhanced” Phone||$49–$199 US (usually subsidized by subscription||Telephony, messaging, limited Internet, color display, games, voice dialing||ARM7, ARM9, some SH, M32/M100||Nucleus, older SymbianOS, Brew/REX|
|Low Tier “Entry/Basic” Phone||$0–$49 US (often free with subscription||Basic telephony, phone book, text messaging||ARM7, legacy regional CPUs||Legacy RTOS (Nucleus, iTRON, etc.)|