The Symbian OS (779886), страница 5
Текст из файла (страница 5)
29]. [Funk 2004, p. 4] has a simple definition. [Davila 2006] defines it neatly as‘semi-radical technology innovation’.15Symbian OS is, of course, itself at risk from the disruptive business model offered byLinux.THE THING ABOUT MOBILE PHONES11Mobile Phone Hardware and SoftwareBaseband (radio ‘modem’) hardware is complex. In effect, the basebandhardware is a complete package in its own right, consisting of CPU,data bus, dedicated memory, memory controller, digital signal processors(DSPs), radio hardware, and so on.The baseband software stack is complex too.
Mobile phone protocolsare complex and require real-time systems to support their signaling timingtolerances. Real-time support cannot be faked. A real-time operatingsystem is required at the bottom of the stack to manage the hardwareand support the layers of software protocols all the way up to thephone-signaling stack.Treating the phone as a black box encapsulated by a communicationsprotocol simplifies the software problem but has drawbacks in terms ofboth speed and capability. The power and speed requirements of thephone’s hardware cannot be ignored.Mobile Phone ApplicationsA typical Symbian OS phone has a complete application suite: phonebook application, email and messaging clients, jotter, clock and alarmapplications, connection and network setup utilities (not to mention webbrowser, camera support and photo album applications, video clip playerand editor, and music player).The application layer requires a full function graphical user interface(GUI) framework to support it, from widget set to full application lifecycle.Most (and probably all) of the expected applications also demand fairlydeep system support from the operating system.While Symbian OS staked its initial claim at the high end of themarket, partly on the strength of its application support, the downwardpush towards the mass-market volumes of mid-range phones does notmean it has to do less.
There are persuasive arguments that the mid-rangeis not defined by functional breadth (the range of available applications)so much as by functional depth (the size of the mailbox, the number offields in a contact, and so on). Equally, critical factors such as performanceare typically more demanding in the mid-range, where users have higherexpectations that things ‘just work’ and lower tolerance for failure.Convergence and CommoditizationPhone functionality is extending in every direction. Two-camera phonesare becoming commonplace, true optical cameras have arrived (withZeiss lenses, for example), as have phones with boom-box stereo speakers,a gigabyte of RAM and a built-in global positioning system (GPS).1616Siemens and Mitac for example have both announced GPS-enabled GSM phones.12WHY PHONES ARE DIFFERENTDevice convergence is not a hypothesis, it is the reality.
As discussedabove, mobile phones have cannibalized the PDA market, appear to haveeroded the digital camera market, and threaten other markets includingthe personal music-player market.At the same time, new technologies and advances in existing technologies continue to be relentlessly absorbed into and commoditized bythe mobile phone market. For example, Wi-Fi is causing the connectionmodel for mobile phones to be reinvented, with hot-spot connectivity offering alternative network options. Meanwhile advances in storagemedia, from flash drive densities to micro hard-drives, challenge theuse-case assumptions for mobile phones.
From being the equivalent ofsnapshot cameras, they have become full video-recording devices; withinternal memories of several gigabytes, they now compete with dedicatedmusic players.While the PC market, for example, has been essentially mature fora decade and now exhibits little more exciting than consolidation, themobile phone market continues to be transformed by convergence andcommoditization.ServicesPossibly the biggest difference between phones and other mobile devicesis the integration of uniquely complex technology with uniquely complexbusiness models.
Phone services are almost as important in the productoffering as immediate phone functionality.Everything about the mobile-phone-network business model is complex, from spectrum licenses to roaming, to network subsidies for phones,to packetization of data and the interaction with legacy technology models, be they fixed-line telephony or radio and TV broadcasting or theInternet.This complexity has its impact on the software in mobile phones,whether it is the requirement to support custom network services, toenable customized applications, or to be invisible beneath the top-linebranding of networks and vendors (which leads, for example, to thedemand to support custom user interfaces).Open PlatformsSymbian OS sets out to be an open application platform, in other wordsa platform for which anyone can write and sell (or share, or simply giveaway), installable software, whether end-user applications and utilities orservice and feature extensions.Symbian therefore must provide the development tools and support(tool chains, support programs, compatibility guarantees and documentation, including books) needed by external developers to understand andTHE THING ABOUT MOBILE PHONES13use the system, and to design and write stable and secure applications torun over various releases of the operating system and on various phonemodels, including phones from different vendors.Open platforms are easy to promise and hard to deliver.
Success canpresent acute problems of scaling. Thus, for example, while vendors werebringing to market only one or two models per year, it was possible forthird parties to test their applications on all available phones. Those daysare long gone, with the biggest Symbian licensees sometimes bringing outa dozen or more Symbian-based models in a single quarter.
Managing thesuccess of the platform means managing compatibility better; adoptingand adhering to open standards including tool and language standards(standard C++, the ARM EABI, and so on); producing more and betterdocumentation; providing more developer services such as the SymbianSigned program; the list could go on. In turn, these things can only beachieved by creating a healthy ecosystem around the platform to increasethe overall pool of available resources and maximize the communitycontribution.User ExpectationsUsers expect and demand rock-solid stability and performance from theirphones; desktop computer performance standards are not acceptable.At the same time, users are fickle, tending either to be infinitely happyor infinitely unhappy.17 When they are infinitely unhappy, they returnthe phone.
However, it is not always easy to understand precisely whattriggers happiness or unhappiness (the trigger often seems removed fromordinary measures of good, bad and defective behavior). Desktop PCusers seem more likely to be either infinitesimally happy (the machinehas not crashed) or unhappy (it crashed but they did not lose much data).The conclusion is that phones really are different from other systemsand they are complex.17Thanks to Phil McKerracher for this idea.2The History and Prehistoryof Symbian OS2.1 The State of the ArtSymbian OS reached market for the first time towards the end of 2000,with the release of the Ericsson R380 mobile phone in November andthe announcement almost immediately afterwards of the Nokia 9210Communicator, which came to market in June 2001. Both phones werebased on versions of what had previously been known as Psion’s EPOCoperating system.
The final EPOC release was EPOC32 Release 5 (strictlyspeaking, the final version was the full Unicode build, designated ER5u).The first release of Symbian OS was therefore designated v6.0.Since then, well over a hundred phone models later (the 100th model1shipped in early Q2, 2006) and with more than 100 million (and rising)cumulative unit sales, Symbian OS has undergone continuous evolutionto keep pace with the rapidly changing technology in the market it targets:communications-enabled mobile terminals including, of course, mobilephones.The latest release of Symbian OS is v9.
In v9, and its precursor v8,dozens of new APIs offer access to services and technologies whichin many cases simply did not exist when Symbian OS first launched.2Bluetooth support was one of the earliest additions (v6); Wi-Fi is oneof the most recent (v9). Telephony support, meanwhile, has evolvedfrom basic GSM and GPRS (in v6) to include EDGE (v7), CDMA (v8)and 3G (v8). Networking support including IPSec has been integral from1The Nokia 3250 (also, as it happens, the first Symbian OS v9.1 phone to market) wasthe 100th model, reaching the shops in April 2006, soon followed by the Sony EricssonP990, also based on v9.1.2To name just the three most obvious examples, Java ME, Bluetooth and 3G networksdid not exist when Symbian OS was first launched.16THE HISTORY AND PREHISTORY OF SYMBIAN OSthe beginning, evolving to a dual IPv4/v6 stack in v7 and enabling fullInternet browsing on Symbian phones, with recent additions includingsupport for VPN clients.
New multimedia APIs (v8) support the high datarates required for two-way streaming and high definition interactive TV(DVB-H). The graphics system supports vector graphics (OpenGL ES inv8), with direct screen access and double resolution displays. The newplatform security model (v9) enables the platform to remain open, butsafe, with a signing service to support trusted application download. Thelist goes on.The foundation for these latest services is the new real-time kernel(available in v8.1b and from v9), supporting the multiple fast interruptsneeded for high data throughput, the latest generation of ARM processorarchitectures (ARMv6 is supported in v9) and single core phone designs.The latest Symbian OS phones are full multimedia devices, includingmultimegapixel cameras with integrated flash and optical zoom, supportfor hot-swappable media cards up to 2 GB, MP4 (video) and MP3 (audio)players (supporting WMA and AAC too), 24-bit color (16.7 million colors),not to mention Wi-Fi, and Universal Plug and Play (UPnP, which enablesremote control of compatible PCs, audio systems and TVs from a Symbianphone).Having achieved its first ‘1 million phones shipped’ year in 2002(2.1 million Symbian OS phones were shipped that year, compared with0.5 million the year before), Symbian OS achieved 1 million phonesshipped in one quarter in Q1 2003, and 1 million phones shipped in onemonth in December 2003.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
