Symbian OS is a full-featured mobile operating system that resides in most of today’s smartphones. The demand for smartphone software is growing as these devices become more powerful and more widely used.

While Symbian OS-based smartphones are shipped with a variety of useful applications built in, an exciting aspect of these phones is that they are ‘open’. This means that users can download, install and uninstall applications written by third-party developers (or by the users themselves). No special carrier service or device manufacturer’s agreement is needed to distribute new smartphone applications – they can be downloaded by the user from a PC to the smartphone through a link such as USB or using Bluetooth technology (limited by the smartphone’s storage space, of course).

Symbian OS provides a great opportunity for software developers since smartphone users are always looking for good applications for their devices. There is a growing list of Symbian OS software titles available as freeware or as paid downloads on numerous Internet sites (www.handango.com and www.epocware.com are good examples). Available smartphone applications range from productivity, entertainment, multimedia and communications software to programs that can count fast food calories, improve your golf swing, keep diaries and calculate foreign currency exchange. And – business opportunities aside – sometimes it’s just plain fun writing your own code to run on your own smartphone.

The purpose of this book is to help software developers create good software for Symbian OS-based smartphones. But, before launching into programming for Symbian OS, this chapter introduces the smartphone itself and gives an overview of its features and associated technologies. Understanding the smartphone’s range of features helps the programmer to exploit them to their full potential.

I’ll also discuss the company Symbian Ltd, give an introduction to Symbian OS and discuss how Symbian OS and other operating systems fit into the marketplace.

Smartphone Concept

A mobile phone that fits in your pocket and lets you communicate from and to anywhere in the world is an amazing invention. Like most inventions, mobile phones are built on a chain of prior technological advancements.Without advancements such as integrated circuits, microprocessors, semiconductor miniaturization, battery technology and, of course, the invention of telephone and radio, the modern mobile phone would not be possible.

Smartphones combine the mobile phone with another stream of technology: the computer, which adds the ‘smart’ in smartphone. Computers have progressed from centralized mainframes to personal computers with user-downloadable applications and graphical user interfaces. With the introduction of the Internet and email, the PC is a part of everyday life as a productivity, entertainment, and communication device. Laptops were introduced to allow PCs to be portable. Then came the mobile computing device known as the PDA – a true handheld computer.

Since the PDA and the mobile phone are both mobile devices, it’s only natural that we would want to combine them into one device. After all, you only have so much pocket or purse space! This is the basic idea of a smartphone – but a smartphone is more than just the sum of two devices.

Smartphone Features

Like PDAs, smartphones can run applications such as organizers, games, and communications programs (e.g. email, browser). They can, of course, also make telephone calls. The smartphone’s goal, however, is not just to limit the number of devices you carry, but also to combine mobile phone and computing technologies in a synergistic way. A simple example is the ability to pull up a person’s contact information or even their picture, hit a button and automatically dial the person’s phone number. Other examples include taking a picture, adding some text, and sending it instantly to a PC or another smartphone user. There are many more examples of this – and certainly many that have not even been thought of yet.

How Smartphones Communicate

Smartphones, like traditional mobile phones, use radio to communicate with base towers, which in turn act as gateways into landline-based communication infrastructures. While traditional mobile phone systems are based mainly on relaying voice communication between the wireless handset and the wired telephone infrastructure, smartphones provide more features that rely on network data transfer. After all, the basic concept of the smartphone is to combine a mobile phone with a networked PDA. Improved data transfer is the current challenge for next generation mobile communications; unlike voice transfer which, requires a fixed bandwidth, the rule for data transfer is the faster the better.

Generations of Mobile Communication

With faster data speeds come better services. For example, when the bandwidth reaches a certain threshold, applications and services that transfer real-time audio and video become possible. The industry goals in wireless data communications have been categorized into generations – each generation includes a target data bandwidth as well as a set of data services available for it:

First Generation (1G): Original analog mobile phone technology

Second Generation (2G): Voice-centric digital systems with increased coverage and capacity and messaging

Third Generation Transitional (2.5G): Stepping stone to 3G with always-on network connections and bandwidths up to 170 Kbps allowing better Internet browsing, email, and some audio and video; GPRS has been the dominant technology

Third Generation (3G)/Fourth Generation (4G): Bandwidths up to 2Mbps and 200 Mbps respectively for high-end services such as video teleconferencing.

The topic of wireless communication protocols is vast and could easily take up another book. But let’s briefly cover some of the key communication technologies that apply to smartphones.

GSM

GSM, short for Global System for Mobile Communication, is a digital cell-based communication service that started in Europe, and has quickly spread throughout most of the world. A notable exception is the US, where CDMA is the dominant standard; however, GSM is gaining popularity there. GSM is the most supported protocol in smartphones.

GSM was designed for circuit-switched voice communication. Circuitswitched means that fixed bandwidth is reserved for each direction of a phone call for the entire duration of the voice call, whether you are talking or not.

Although originally designed for voice, GSM now has a variety of higher bandwidth data services (e.g. GPRS and EDGE) available, running on top of the base GSM protocol. This allows for faster data transfer, as we will see shortly.

The following types of GSM exist, each using its own band in the frequency spectrum: GSM 850, GSM 900, GSM 1800 and GSM 1900. The number indicates the frequency band, in MHz, that the protocol uses. Mobile phones supporting GSM 900 and GSM 1800 will ensure coverage in Europe and many other areas outside of the US, while GSM 850 and GSM 1900 are used in the US (mostly GSM 1900).

Fortunately, smartphones support multiple bands to ensure as wide a coverage as possible. It’s common to have tri-band phones that support GSM 900, GSM 1800 and GSM 1900 to ensure maximum international coverage – although some still offer separate US models to reduce costs.

A GSM phone uses a Subscriber Identification Module (SIM) to gain access to the GSM network. A SIM contains all the pertinent information regarding a user’s account including the services allowed. It is used to identify the user to the GSM network for billing purposes. The user can switch their SIM from one GSM phone to another, provided that the phone is not locked either to a specific carrier or to the carrier that the SIM is associated with.

CDMA

CDMA, which stands for Code Division Multiple Access, is a mobile phone standard that competes with GSM. CDMA currently dominates in the US and Korea, while GSM dominates virtually everywhere else. CDMA supports a high speed data mode called CDMA2000 1xRTT, which tends to hover around 50–70 Kbps, bursting up to 144 Kbps. The forthcoming CDMA2000 1xEV-DO supports rates up to 2.4 Mbps, but initial reports on the Verizon Wireless network in two test markets (San Diego and Washington, DC) made in 2003 show probable speeds of 500–800 Kbps, with peak data rates of 1.2 Mbps.

There are some smartphones based on CDMA, such as the Palm Treo 600 (both GSM and CDMA models are available). At the time of writing, however, there are no CDMA Symbian OS-based smartphones, although several do support W-CDMA.

CSD

CSD, short for Circuit Switched Data, is the most basic mode of transferring data over a circuit-switched connection like GSM. The connection is established by dialing the number of an ISP, in the same manner that a dial-up connection is started on a land-based telephone line using a PC modem. With CSD you do not need an extra data plan to send data, as you do for GPRS, which costs more (see Section 1.2.6). You can use your existing voice minutes. There are two major disadvantages to using CSD, however. First, it takes a long time to connect since it involves dialing a number and waiting for the server to answer the call. Second, it’s slow – data transfer speed is only about 9.6 Kbps.

In GSM-based smartphones, this mode is referred to as ‘Dial’ or simply as GSM data. Earlier smartphones such as the Nokia 9290 rely entirely on this mode of data communication.

GPRS

GPRS, short for General Packet Radio Service, is a wireless technology that allows the smartphone user to quickly connect to the network and obtain good data rates. Connection time is fast since GPRS does not require any dialing (unlike CSD), and the smartphone feels as if it is always connected.

GPRS runs on top of the GSM protocol. While GSM alone is circuitswitched, GPRS is based on packet-switching technology. This means that the radio bandwidth is used only when data is actually transferred, even though you are constantly connected (circuit-switching keeps the full bandwidth reserved throughout a connection).

GPRS, in theory, supports bandwidths up to 170 Kbps. In practice, however, you’ll get between 20 and 60 Kbps depending on network conditions – but this is still significantly faster than the GSM dialup data rate! The best way to think of the speed of GPRS is that it matches approximately with a PC connected to the network via a wired telephone modem. However, GPRS can feel better than dialup since it connects almost instantly to the network without the lengthy delay involved in dialing a number and establishing a call.

GPRS is a highly usable communication feature and a good preview of future wireless data communication technologies. Since it is a stepping stone to 3G technology, it is categorized as 2.5G technology. GPRS is available on most newer smartphones.

HSCSD

HSCSD is the high speed version of CSD. HSCSD is another 2.5G standard that supplies a comparable speed to that of GPRS (although on the lower side in many cases), but with a significant difference – the bandwidth is reserved to the smartphone throughout the connection. This is because HSCSD, like CSD and GSM, is a circuit-switched technology. This makes HSCSD better suited for applications that require a constant bit rate, although the practical bandwidth is rather low for good real-time multimedia transfers – which benefit the most from constant bit rates.

HSCSD is not widely used due to the high costs of implementation. The Nokia 6600 and the Motorola A920 are examples of smartphones that support HSCSD.

EDGE

EDGE, short for Enhanced Data Rates for GSM Evolution, is a GSM-based protocol that provides theoretical speeds up to 384 Kbps. It is a 2.5G technology that is sometimes referred to as 3G because of its higher speed. It is not yet as widely used as GPRS, but is gaining support. For example, AT&T has deployed EDGE on its GSM networks in the USA, reaching speeds of around 90 Kbps in practice. Smartphones such as the Nokia 9300 and Nokia 6620 support EDGE.

UMTS

UMTS, short for Universal Mobile Telecommunication Services, is a high speed data transfer protocol which supports bandwidths up 2 Mbps. This protocol is the basis of third generation mobile communications that make many media-rich services a possibility. This is where smartphones will really shine! UMTS is not based on GSM technology – it uses a technology called W-CDMA. However, the UMTS platform is designed to work with GSM systems to ease its deployment. Although it seems slow in coming, once this communication platform becomes widely implemented, it will revolutionize the way people use smartphone devices.

Sentrymobile Communications, Inc

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