When the BlackBerry debuted in 1999, carrying one was a hallmark of powerful executives and savvy technophiles. People who purchased one either needed or wanted constant access to e-mail, a calendar and a phone. The BlackBerry's manufacturer, Research in Motion (RIM), reported only 25,000 subscribers in that first year. But since then, its popularity has skyrocketed.
In September 2005, RIM reported 3.65 million subscribers, and users describe being addicted to the devices. The BlackBerry has even brought new slang to the English language. There are words for flirting via BlackBerry (blirting), repetitive motion injuries from too much BlackBerry use (BlackBerry thumb) and unwisely using one's BlackBerry while intoxicated (drunk-Berrying). While some people credit the BlackBerry with letting them get out of the office and spend time with friends and family, others accuse them of allowing work to infiltrate every moment of free time.
In this article, we'll examine the "push" technology at the center of the device's popularity, RIM's former dispute with patent holder NTP Incorporated and its current dispute with Visto Corporation. We'll also explore BlackBerry hardware and software.
"Push" Technology
RIM Revenue
1999: $47,342,000
2005: $1,350,447,000
Source:
2000 RIM Annual Report
A PDA does a lot of the same things a BlackBerry does, and the PDA made its debut several years before the BlackBerry. But until recently, the only way to make the information on most PDAs match the information on a person's computer was to automatically or manually sync the PDA. This could be time-consuming and inconvenient. It could also lead to exactly the conflicts that having a PDA is supposed to prevent. For example, a manager might schedule a meeting on the PDA, not knowing that an assistant had just scheduled a meeting for the same time on a networked calendar.
A BlackBerry, on the other hand, does everything a PDA can do, and it syncs itself continually through push technology. BlackBerry Enterprise Server or Desktop Redirector software "pushes," or redirects, new e-mail, calendar updates, documents and other data straight to the user over the Internet and the cell phone network.
First, the software senses that a new message has arrived or the data has changed. Then, it compresses, packages and redirects the information to the handheld unit. The server uses hypertext transfer protocol (HTTP) and transmission control protocol (TCP) to communicate with the handhelds. It also encrypts the data with triple data encryption standard (DES) or advanced encryption standard (AES).
A person can send and receive messages and phone calls on a BlackBerry from virtually any location.
The software determines the capabilities of the BlackBerry and lets people establish criteria for the information they want to have delivered. The criteria can include message type and size, specific senders and updates to specific programs or databases.
Once all of the parameters have been set, the software waits for updated content. When a new message or other data arrives, the software formats the information for transmission to and display on the BlackBerry. It packages e-mail messages into a kind of electronic envelope so the user can decide whether to open or retrieve the rest of the message.
BlackBerry Devices in the United States
70 percent of BlackBerry subscribers live in the United States. Source: Washington post
The BlackBerry listens for new information and notifies the user when it arrives by vibrating, changing an icon on the screen or turning on a light. The BlackBerry does not poll the server to look for updates. It simply waits for the update to arrive and notifies the user when it does. With e-mail, a copy of each message also goes to the user's inbox on the computer, but the e-mail client can mark the message as read once the user reads it on the BlackBerry.
People describe BlackBerry use as an addiction, and this is why. Not only do they give people constant access to their phones, they also provide continual updates to e-mail, calendars and other tools.
Lately, RIM had been dealing with issues of patent infringement. We'll look at that next.
The Patent Dispute
Patent law can be tricky, and the claims companies make in their patents can be hard to quantify. But here is the basic dilemma that RIM and the BlackBerry were facing -- NTP Incorporated holds several patents for wireless e-mail technology. RIM's push technology is similar to, but more complex than, the technology NTP has patented. NTP had accused RIM of patent infringement, and judges and juries agreed. The patent dispute and a delayed rollout of new BlackBerry models caused a slight slowdown in RIM's rapid growth.
The dispute between NTP and RIM started in 2001, when NTP sued RIM. Courts have generally ruled in NTP's favor, granting monetary settlements and injunctions against RIM. RIM, however, has appealed the rulings and had requested a review of NTP's patents. The United States Patent and Trademark Office (USPTO) has overturned several of the patents in question.
People compose e-mail on a BlackBerry using a QWERTY keyboard and typing with their thumbs. Unfortunately, the BlackBerry's e-mail capabilities are the focus of a patent dispute.
In November of 2005, a United States district judge ruled that a previous monetary settlement between the two companies was not enforceable. On January 23, 2006, the United States Supreme Court turned down RIM's request to review the district court ruling. The big concern was that this decision would lead to an injunction prohibiting BlackBerry sales and service in the United States. The U.S. Department of Justice requested a 90-day stay for essential government employees in the event of an injunction. RIM suggested the possibility of a software work-around that would not infringe on NTP's patents, and RIM and NTP began negotiations through a court-appointed mediator.
RIM and NTP have settled their dispute. The cost -- $612.5 million. The result -- NTP grants RIM a license to NTP's patents. According to a press release issued by both companies on March 3, 2006, here's the agreement:
"The licensing and settlement agreement relates to all patents owned and controlled by NTP and covers all of RIM's products, services and technologies. NTP grants RIM an unfettered right to continue its business, including its BlackBerry® related business. The resolution permits RIM and its partners to sell RIM products and services completely free and clear of any claim by NTP, including any claims that NTP may have against wireless carriers, channel partners, suppliers or customers in relation to RIM products or services, (including BlackBerry Connect and Built-In technology), or in relation to third party products and services, to the extent they are used in connection with RIM products and services."
Next, we'll look at the BlackBerry's hardware and software.
Future Cases?
Although now settled, the RIM/NTP dispute raises the question of why other companies that provide smart phones with push technology are not in court as well. Some of these companies have licenses from NTP to use patented technology. Others use technology that does not conflict with NTP's patents. Regardless of whether an injunction eventually shuts down RIM's business in the United States, more companies are likely to introduce PDAs and smart phones with push e-mail and data capabilities, until constant access to e-mail and an updated calendar is as common as a cell phone.
Blackberry Hardware
We took apart a BlackBerry similar to this 6700 model.
A BlackBerry can do everything that a cell phone can do, including sending text messages via SMS. It's also an organizer, a calendar, an e-mail client, a Web browser, a two-way pager and a palm-top computer. Although it can do some of the same things a computer can, it doesn't have to be in a WiFi hot spot to work -- it uses the cell phone network as well as 802.11b WLAN. To do all this, it combines the components of a cell phone and a PDA.
Some BlackBerry models have the same form factor and components as a smart phone. Others look more like PDAs or palmtop computers. Specific components can vary from one model to another, but in general the visible parts of a BlackBerry are:
LCD display
QWERTY keyboard
Click wheel
On/off, escape and other keys
Headset jack
USB charger connection
Antenna (interior on some models)
Indicator light to advise users of new messages or data
From the outside of the unit, you can also see where the microphone and speaker are located as well as where to access the rechargeable lithium ion battery.
The BlackBerry rechargeable battery.
A printed circuit board connects everything inside the case, including:
Light source for the LCD screen
32-bit microprocessor
Memory (usually flash and RAM)
Bluetooth transmitter (in some models)
Wireless modem (in some models)
The internal parts of the BlackBerry.
Unlike many earlier PDAs, which used touch screens as a user interface, the BlackBerry has a keyboard designed for use with the thumbs. This keyboard operates much like the keyboard of your computer, with one notable difference. Most computer keyboards use dome switches, and each key lies over one switch. Pressing the key activates the switch. In a BlackBerry, however, rows of dome switches lie between the rows of keys. Each key has actuators that press one or more of the switches adjacent to it.
The underside of the BlackBerry keyboard.
The BlackBerry's software uses a lookup table to match each letter with a specific combination of dome switches. This layout uses fewer switches, allowing a smaller keyboard.
BlackBerry smart phones have even less space for a keyboard, so each key corresponds to more than one letter. Predictive text software called SureType lets a person type normally and determines the right word as the person types. People can also use multiple taps on each key to select different letters as most people currently do to send text messages on their cell phones.
Next, we'll look at the software that drives the BlackBerry.
Alternatives to BlackBerry
The BlackBerry isn't the only handheld unit that can deliver e-mail straight to users. Other options include:
Palm Treo
T-Mobile sidekick/Danger Hiptop
Windows Mobile Pocket PC
Companies like visto and intellisync also provide cross-platform push e-mail services.
So why don't users just switch to another option? First, many are accustomed to the devices and services they're already using. Second, the BlackBerry's popularity has led to a wide range of third-party applications, some of which are critical to certain businesses and are not available through other devices and services.
BlackBerry Software
A BlackBerry 8700C
In addition to the push technology discussed earlier, a BlackBerry requires a variety of sofware on the handheld unit itself and on servers and desktops. The devices are part of a network that includes handhelds, handheld software, desktop software and server software.
The BlackBerry unit uses a proprietary BlackBerry operating system and usually includes e-mail, Web browsing, instant messaging and personal information management (PIM) software. Third-party developers have created a wide variety of other programs for the BlackBerry, like games and productivity applications.
Other third-party programs are customized applications that let people get data and updates from proprietary sales, data collection and other business software. Many of these use a browser interface and e-mail messages for data retrieval. Users get an e-mail message with a link they can click to make a phone call, view data or log in to a service. SSL and TLS encryption protect information and data.
Since a BlackBerry has less memory and processing power than a computer, each of these programs has to be relatively small and efficient. Web pages have to be simple and not rely on frames or applets, and they're most effective when they use minimal colors. BlackBerry developers use a Java development environment that lets them simulate a BlackBerry and make sure their programs are compatible.
Businesses that employ multiple BlackBerry users often use the BlackBerry Enterprise Server software to manage each BlackBerry's connection with the corporate network. The software runs behind the corporate firewall, and pushes information to the handheld units. System administrators can also use the server-side software to update BlackBerry units wirelessly.
Individual users can run BlackBerry Desktop Redirector software on their computers, which plays the same role as the Enterprise Server but on a smaller scale. The Desktop Redirector sends information in small pieces so it doesn't overload the person's connection or deliver unnecessary information to the BlackBerry. The computer has to be on and running in order for the redirector to work.
Read on for lots more information about PDAs, smart phones, the BlackBerry patent dispute and other topics.
BlackBerry & 9/11
During and after the September 11 terrorist attacks, many cell phone networks could not handle the high volume of callers, particularly in the New York City area. At the time, all BlackBerry handhelds used a proprietary network. The BlackBerry network continued to work normally, leading to increased BlackBerry use among police, fire fighters and other emergency workers. Now, most BlackBerry handhelds and phones use the same networks as other cell phones. Using one requires a cell phone service plan with data capabilities.
Smartphones blur the line between cell phones and PDAs.
Think of a daily task, any daily task, and it's likely there's a specialized, pocket-sized device designed to help you accomplish it. You can get a separate, tiny and powerful machine to make phone calls, keep your calendar and address book, entertain you, play your music, give directions, take pictures, check your e-mail, and do countless other things. But how many pockets do you have? Handheld devices become as clunky as a room-sized supercomputer when you have to carry four of them around with you every day.
A smartphone is one device that can take care of all of your handheld computing and communication needs in a single, small package. It's not so much a distinct class of products as it is a different set of standards for cell phones to live up to. This article explores what makes a cell phone a smartphone, how the idea came about and what you can do with it.
Unlike many traditional cell phones, smartphones allow individual users to install, configure and run applications of their choosing. A smartphone offers the ability to conform the device to your particular way of doing things. Most standard cell-phone software offers only limited choices for re-configuration, forcing you to adapt to the way it's set up. On a standard phone, whether or not you like the built-in calendar application, you are stuck with it except for a few minor tweaks. If that phone were a smartphone, you could install any compatible calendar application you like.
Since cell phones and PDAs are the most common handheld devices today, a smartphone is usually either a phone with added PDA capabilities or a PDA with added phone capabilities. Here's a list of some of the things smartphones can do:
Send and receive mobile phone calls – some smartphones are also WiFi capable
Personal Information Management (PIM) including notes, calendar and to-do list
Communication with laptop or desktop computers
Data synchronization with applications like Microsoft Outlook and Apple's iCal calendar programs
E-mail
Instant messaging
Applications such as word processing programs or video games
Play audio and video files in some standard formats
Future applications promise to be even more impressive. For example, the Nokia 6131 is a phone utilizing near field communication (NFC) to allow the phone to act as a wireless credit card. The phone uses a two-way communication system to transfer payment information to pads at certain retail stores. Currently, it’s still in the trial phase of development.
The Layers of a Smartphone
The Hardware Today's smartphones run on processors with clock speeds ranging from 100 – 624 MHz (with a 1 GHz processor looming on the horizon), which would be mind-numbingly slow if they were used to run today's desktop computers. Many smartphones use power-efficient ARM processors, which are also found in routers, printers, and other embedded devices like Smart Watches and MP3 players. They have a certain amount of on-board memory in the tens of megabytes, and many have slots for removable memory formats like SD and MMC cards as well.
Chips used in smartphones
Along with processors, smartphones also have computer chips that provide functionality. Phones with cameras have high-resolution image sensors, just like digital cameras. Other chips support complex functions such as real-time web browsing, sharing multimedia files or playing music without placing too great a demand on the phone’s battery. Some manufacturers develop chips that integrate multiple functions to help reduce the overall cost (fewer chips produced per phone help offset production costs).
The Innovations of Apple
Apple’s iPhone has several hardware elements that are sure to become industry standards. The iPhone has an accelerometer that allows you to change the view from portrait to landscape layout by simply turning the phone 90 degrees. There are no dial buttons on the iPhone; all calls are made by using the touchscreen. In order to prevent you from accidentally dialing Peru when you talk on the phone, Apple has included proximity sensors to turn off the display when you lift the phone to your ear. There are also ambient light sensors that help the iPhone save power by adjusting the brightness of the display based on how much ambient light is present.
The Software Software for smartphones can be visualized as a software stack. The stack consists of the following layers:
kernel - management systems for processes and drivers for hardware
middleware - software libraries that enable smartphone applications (such as security, web browsing, messaging, etc.)
application execution environment (AEE) - application programming interfaces, which allow developers to create their own programs
user interface framework - the graphics and layouts seen on the screen
application suite - the basic applications users access regularly such as menu screens, calendars and message inboxes
Special Considerations
Although cell phones share similarities with laptop computers, pagers and other devices, they have some peculiarities that make their development needs unique.
For example:
When you're making a call on a cell phone, you want to have access to other features (like an address book and calendar) at the same time.
Cell phones need to be "always on" like a standard landline phone, but efficient enough to run on a battery charge for as long as possible.
They need to be as functional as possible whether or not they are connected to voice and data networks at a given moment.
While a computer has pretty standard input methods -- almost all of them start with a keyboard and mouse by default -- a phone may have a number pad, a modified keyboard, a touch screen or some combination thereof.
Smartphone Operating Systems
The most important software in any smartphone is its operating system (OS). An operating system manages the hardware and software resources of smartphones. Some OS platforms cover the entire range of the software stack. Others may only include the lower levels (typically the kernel and middleware layers) and rely on additional software platforms to provide a user interface framework, or AEE. The smartphone operating systems are:
A Nokia N92 with Symbian OS
Symbian Symbian OS is the operating system for more than 100 different models of phones. The operating system consists of the kernel and middleware components of the software stack. The upper layers are supplied by application platforms like S60, UIQ, and MOAP. Though it's dominant in the market right now, with an estimated market share of 51 percent [Source: LinuxDevices.com],the research firm, The Diffusion Group, estimates that Linux and Microsoft will hold more of the market share than Symbian by 2010.
Linux
The Linux Smartphone
Linux is unique among the other operating systems in that its development is driven by a community of developers rather than by a central company. According to ARCchart, the Linux OS supports more processors than any other operating system on the market, though the most popular phone models still use the Symbian OS. There are some drawbacks to the system, however. Since Linux is an organic OS, with developers constantly changing and updating it even at the kernel level, platforms based on Linux code can be very different from one another. Some smartphone companies find the risk too great to invest in Linux. Six telecommunications companies are responding to this by forming the LiMo foundation, an organization that is attempting to create a standardized Linux platform.
Windows Mobile
The T-Mobile SDA Windows Mobile Smartphone
The Windows Mobile OS encompasses the entire software stack from the kernel to the application interface. The OS is based off of Window CE.NET. On February 12, 2007, Microsoft unveiled Windows Mobile 6, the latest version of the software platform. Much of the strength of this OS lies in the compatibility with the Microsoft Office suite of programs.
Java Some smartphones have operating systems based on the Java programming language. The SavaJe OS is a Java-based system that includes everything from the kernel to the user interface framework and application suite. By using the Java language, the OS allows manufacturers or users to customize the interface as much as they like. Java-based phones have not made a huge impact in the marketplace so far, but some analysts think the operating system could gain ground while the big boys battle for the lion’s share of the market.
Garnet OS Formerly known as Palm OS, this operating system combines a Linux-based foundation with applications written for the old Palm OS. The Palm OS was mainly used in PDAs, though the Treo line of smartphones used it as well. Phones using the Garnet OS should become available in late 2007.
Unique Operating Systems Apple’s iPhone uses a variation of the Mac OS, known as OS X. The RIM BlackBerry has its own proprietary OS as well.
Network Protocols
Smartphones use cell-phone network technology to send and receive data (such as phone calls, web browsing, file transfers, etc.). Developers classify this technology into generations. The first generation includes analog cell phone technology. Digital cell phones require more advanced protocols, which constitute the second generation. Between generation two and three, network engineers created protocols that are more advanced than generation two’s digital technology but not so innovative that they are a truly new generation. Developers refer to these protocols as generation 2.5. This generation includes several early smartphone protocols, some of which are still used today.
Treo 700w: Palm's First Windows Mobile Smartphone
General Packet Radio Services (GPRS) is a wireless, packet-based communication service and until recently was the standard 2.5G protocol used in most smartphones. Unlike a circuit-switched voice connection, this is a packet-switched, "always on" connection that remains active as long as the phone is within range of the service. It allows smartphones to do things like run applications remotely over a network, interface with the Internet, participate in instant messenger sessions, act as a wireless modem for a computer and transmit and receive e-mails. GPRS can send and receive data at a rate of 114 kilobytes per second. Some smartphones in the United States still use this protocol, though newer, faster protocols are available.
One protocol that is faster than GPRS used in the U.S. market is Enhanced Data GSM Environment (EDGE). EDGE can transmit data at more than three times the rate of GPRS (384 Kbps). Many smartphones in the United States are now using EDGE protocol [Source: Whatis.com]. Still, these protocols are only generation 2.5. Generation three (3G) is the latest in network communication technology. Protocols in 3G transmit data in terms of megabytes per second rather than kilobytes (some as fast as 10 Mbps). While some U.S. carriers support 3G protocols, many still rely on 2.5G technology. Europe and Asia have much stronger 3G integration in their respective cell phone networks. Some 3G protocols are:
Universal Mobile Telecommunication Service (UMTS)
Wideband Code-Division Multiple Access (WCDMA)
High-Speed Downlink Packet Access (HSDPA)
Evolution Data Maximized (EVDO)
Talkin’ ‘bout my generation
Even as smartphone owners in the United States begin to enjoy the benefits of 3G technology, the reality of a fourth generation of protocols may soon be upon us. On February 9, 2007, telecommunications company NTT DoCoMo Inc. revealed the results of a preliminary 4G experiment. Engineers also managed to achieve a 5Gbps (gigabyte per second) transmission rate [Source: NTT DoCoMo inc.]. That’s 500 times faster than 3G protocols!
You can read more about network technologies and protocols in the article How Cell Phones Work.
Flexible Interfaces
The core services on smartphones all tie in to the idea of a multi-purpose device that can effectively multitask. A user can watch a video clip, field a phone call, then return to the video clip after the call, all without closing each application. Or he or she can flip through the digital calendar and to-do list applications without interrupting the voice call. All of the data stored on the phone can be synchronized with outside applications or manipulated by third-party phone applications in any number of ways. Systems supported by smartphones include:
Bluetooth A short-range, wireless radio service that allows phones to wirelessly link up with each other and with other nearby devices that support it. This includes things like printers, scanners, input devices , computers and headsets.
Some varieties of Bluetooth only allow communication with one device at a time, but others allow simultaneous connection with multiple devices. To learn more, check out How Bluetooth Works.
Data Synchronization A phone that keeps track of your personal information, like appointments, to-do lists, addresses, and phone numbers, needs to be able to communicate with all of the other devices you use to keep track of those things. There are hundreds of possible platforms and applications you might use for this in the course of a day. If you want to keep all of this data in synchronization with what's on your phone, then you generally have to look for a cell phone that speaks the languages of all of the devices and applications you use. Or you can go out and buy new applications that speak the language of your cell phone.
Smartphone E-mail Application
The Open Mobile Alliance (OMA) is a collaborative organization with the mission to “facilitate global user adoption of mobile data services by specifying market driven mobile service enablers that ensure service interoperability across devices, geographies, service providers, operators, and networks, while allowing businesses to compete through innovation and differentiation” [Source: Open Mobile Alliance]. The OMA formed a Data Synchronization Working Group, which is continuing the work begun by the SyncML Initiative. SyncML is an open-standards project designed to eliminate the trouble of worrying about whether your PIM devices sync up with your phone and vice-versa. The project is designed so that any kind of data can be synchronized with any application on any piece of hardware, through any network, provided that they are all programmed to OMA standards. This includes synchronization over the Web, Bluetooth, mail protocols and TCP/IP networks.
SyncML allows data to be synchronized from a phone to PalmOS, Windows, Mac and Linux applications using Bluetooth, infrared, HTTP or a USB cable. The OMA's SyncML site keeps a list of devices that are compliant with the standard.
Java A smartphone that is compatible with the Java programming language allows the user to load and run Java applications and MIDlets. MIDlets are applications that use a subset of Java and are specifically programmed to run on wireless devices. Java MIDlets include add-ons, games, applications and utilities.
Since there are millions of Java developers worldwide, and the Java development tools are freely accessible, smartphone users can install thousands of third-party applications on their phones. Because of the way the OS architecture of most phones is built, these applications can access and use all of the data on the user's phone. For example, if you don't like the photo caller ID that comes bundled with Symbian Series 60 OS, you can just find one that you like better.
The Future of Smartphones
Honey, can you get the door?
A Dutch wireless company named Waleli has recently developed a way for you to answer your front door, even if you aren’t in the same country as your house. The doorbell and intercom system sends a message to your phone when activated. After you enter your PIN correctly, you can talk to your guest over the intercom, or even unlock your door to let them in.
Smartphones are getting thinner and cheaper, and as a result are entering the consumer market. For the past few years smartphones have been aimed at prosumers, or “professional consumers” (prosumers can also refer to “production consumers”, or consumers who drive the design, production and alteration of a product). Prosumers are generally early adopters of products. They have disposable income and great enthusiasm for particular products or technologies. Smartphone developers find prosumers very useful when designing applications and hardware. As prosumers pick and choose the phones that offer the applications they want, developers can tweak designs and move towards mass production. Analysts predict that one billion smartphone handsets will be sold by 2011 [Source: eCommerce Times].
While input methods will vary, the research firm, ARCchart, forecasts that 38 percent of all mobile phones will use touchscreens or touchpanels by 2012 [Source: LinuxDevices.com]. The iPhone uses an advanced touchscreen, for example, and can even detect multiple points of contact simultaneously.
Security Perhaps the most challenging consideration for the future is security. Smartphones and PDAs are already popular among many corporate executives, who often use their phones to transmit confidential information. Smartphones may be vulnerable to security breaches such as an Evil Twin attack. In an evil twin attack, a hacker sets a server’s service identifier to that of a legitimate hotspot or network while simultaneously blocking traffic to the real server. When a user connects with the hacker’s server, information can be intercepted and security is compromised.
One downside to the openness and configurability of smartphones is that it also makes them susceptible to viruses. Hackers have written viruses that attack SymbianOS phones. The viruses can do things like turning off anti-virus software, locking the phone completely or deleting all applications stored on the phone.
On the other side, some critics argue that anti-virus software manufacturers greatly exaggerate the risks, harms and scope of phone viruses in order to help sell their software. Read more in the article How Cell Phone Viruses Work.
Symbian Skull Virus: Skulls will continuously display a flashing skull animation in the background regardless of what application the user is using.
The incredible diversity in smartphone hardware, software and network protocols inhibit practical, broad security measures. Most security considerations either focus on particular operating systems or have more to do with user behavior than network security.
With data transmission rates reaching blistering speeds and the incorporation of WiFi technology, the sky is the limit on what smartphones can do. Possibly the most exciting thing about smartphone technology is that the field is still wide open. It's an idea that probably hasn't found its perfect, real-world implementation yet. Every crop of phones brings new designs and new interface ideas. No one developer or manufacturer has come up with the perfect shape, size or input method yet. The next "killer app" smartphone could look like a flip phone, a tablet PC, a candy bar or something no one has conceived of yet.
In January 2007, Steve Jobs introduced the Apple iPhone during his keynote address at the Macworld Conference and Expo. In its first appearance onscreen and in Jobs's hand, the phone looked like a sleek but inanimate black rectangle.
Then, Jobs touched the screen. Suddenly, the featureless rectangle became an interactive surface. Jobs placed a fingertip on an on-screen arrow and slid it from left to right. When his finger moved, the arrow moved with it, unlocking the phone. To some people, this interaction between a human finger and an on-screen image -- and its effect on the iPhone's behavior -- was more amazing than all of its other features combined.
And those features are plentiful. In some ways, the iPhone is more like a palmtop computer than a cellular phone. As with many smartphones, you can use it to make and receive calls, watch movies, listen to music, browse the Web, and send and receive e-mail and text messages. You can also take pictures and video (using an iPhone 3GS) with a built-in camera, import photos from your computer and organize them all using the iPhone's software.
In 2008, Apple introduced the second generation iPhone. This iPhone can operate on third-generation (3G) cellular networks and has a GPS receiver. The iPhone also lets you view map and satellite data from Google Maps, including overlays of nearby businesses. Owners of the original iPhone got the opportunity to upgrade the software on their phones. The 2.0 software gives the old phones new functions, but without the GPS receiver or 3G network capability.
In 2009, Apple launched the iPhone 3GS. The newest iPhone models have more storage capacity than earlier iPhones. They also have a better camera that's capable of taking still shots and video at 30 frames per second. Another new feature is a compass, which comes in handy when you need to find your way through unfamiliar territory. Also in 2009 came iPhone OS 3.0, which offered many improvements, such as the ability to cut and paste.
A modified version of the Macintosh OS X operating system used on Apple desktop and laptop computers lets you interact with all of these applications. It displays icons for each application on the iPhone's screen. It also manages battery power and system security. The operating system synchs the phone with your computer, a process that requires a dock much like the one used to synch an iPod. It also lets you multitask and move through multiple open applications, just like you can on a laptop or desktop computer.
But instead of using a mouse or a physical keyboard, the iPhone uses virtual buttons and controls that appear on its screen. This isn't really a new phenomenon -- touch-screens have been part of everything from self-checkout kiosks to smartphones for years. But the iPhone's touch-screen is a little different from many of the others currently on the market. When you touch the screen on a PDA or a Nintendo DS, you typically use a slender, pointed stylus. The iPhone, on the other hand, requires you to use your fingers. It can also detect multiple touch points simultaneously, which many existing touch-screens cannot do.
This article will explore exactly how the iPhone's touch-screen carries instructions from your fingertips to the phone's internal circuitry. We'll also look at the iPhone's features, its hardware and how it compares to smartphones and other electronic devices.
iPhone Touch-screen
Electronic devices can use lots of different methods to detect a person's input on a touch-screen. Most of them use sensors and circuitry to monitor changes in a particular state. Many, including the iPhone, monitor changes in electrical current. Others monitor changes in the reflection of waves. These can be sound waves or beams of near-infrared light. A few systems use transducers to measure changes in vibration caused when your finger hits the screen's surface or cameras to monitor changes in light and shadow.
The basic idea is pretty simple -- when you place your finger or a stylus on the screen, it changes the state that the device is monitoring. In screens that rely on sound or light waves, your finger physically blocks or reflects some of the waves. Capacitive touch-screens use a layer of capacitive material to hold an electrical charge; touching the screen changes the amount of charge at a specific point of contact. In resistive screens, the pressure from your finger causes conductive and resistive layers of circuitry to touch each other, changing the circuits' resistance.
Back-side Touch-screen?
According to Apple's patent filings, the company may have considered incorporating a touch-screen on the back of the iPhone rather than the front.
Most of the time, these systems are good at detecting the location of exactly one touch. If you try to touch the screen in several places at once, the results can be erratic. Some screens simply disregard all touches after the first one. Others can detect simultaneous touches, but their software can't calculate the location of each one accurately. There are several reasons for this, including:
Many systems detect changes along an axis or in a specific direction instead of at each point on the screen.
Some screens rely on system-wide averages to determine touch locations.
Some systems take measurements by first establishing a baseline. When you touch the screen, you create a new baseline. Adding another touch causes the system to take a measurement using the wrong baseline as a starting point.
The Apple iPhone is different -- many of the elements of its multi-touch user interface require you to touch multiple points on the screen simultaneously. For example, you can zoom in to Web pages or pictures by placing your thumb and finger on the screen and spreading them apart. To zoom back out, you can pinch your thumb and finger together. The iPhone's touch screen is able to respond to both touch points and their movements simultaneously. We'll look at exactly how the iPhone does this in the next section.
Multi-touch Systems
To allow people to use touch commands that require multiple fingers, the iPhone uses a new arrangement of existing technology. Its touch-sensitive screen includes a layer of capacitive material, just like many other touch-screens. However, the iPhone's capacitors are arranged according to a coordinate system. Its circuitry can sense changes at each point along the grid. In other words, every point on the grid generates its own signal when touched and relays that signal to the iPhone's processor. This allows the phone to determine the location and movement of simultaneous touches in multiple locations. Because of its reliance on this capacitive material, the iPhone works only if you touch it with your fingertip -- it won't work if you use a stylus or wear non-conductive gloves.
A mutual capacitance touch-screen contains a grid of sensing lines and driving lines to determine where the user is touching.
A self capacitance screen contains sensing circuits and electrodes to determine where a user is touching.
The iPhone's screen detects touch through one of two methods: Mutual capacitance or self capacitance. In mutual capacitance, the capacitive circuitry requires two distinct layers of material. One houses driving lines, which carry current, and the other houses sensing lines, which detect the current at nodes. Self capacitance uses one layer of individual electrodes connected with capacitance-sensing circuitry.
Both of these possible setups send touch data as electrical impulses. In the next section, we'll take a look at exactly what happens.
iPhone Processor
The iPhone's processor and software are central to correctly interpreting input from the touch-screen. The capacitive material sends raw touch-location data to the iPhone's processor. The processor uses software located in the iPhone's memory to interpret the raw data as commands and gestures. Here's what happens:
Signals travel from the touch screen to the processor as electrical impulses.
The processor uses software to analyze the data and determine the features of each touch. This includes size, shape and location of the affected area on the screen. If necessary, the processor arranges touches with similar features into groups. If you move your finger, the processor calculates the difference between the starting point and ending point of your touch.
The processor uses its gesture-interpretation software to determine which gesture you made. It combines your physical movement with information about which application you were using and what the application was doing when you touched the screen.
The processor relays your instructions to the program in use. If necessary, it also sends commands to the iPhone's screen and other hardware. If the raw data doesn't match any applicable gestures or commands, the iPhone disregards it as an extraneous touch.
All these steps happen in an instant -- you see changes in the screen based on your input almost instantly. This process allows you to access and use all of the iPhone's applications with your fingers. We'll look at these programs and the iPhone's other features in more detail in the next section, as well as how the iPhone's cost measures up to its abilities.
iPhone Features
iPhone Specs
Apple is fairly secretive about the exact processors and circuitry found in the iPhone. Here's a glimpse of what it takes to keep the iPhone 3GS running:
3.5-inch, 163 ppi screen with a glass protective covering
Battery with up to 10 hours of talk time on 2G networks, 5 hours on 3G, 6 hours of Internet use on WiFi, 7 hours of video playback, 24 hours of audio playback and 300 hours of standby time
Macintosh OS X operating system
3.2-megapixel camera capable of shooting video at 30 frames per second
Ambient light sensor
Accelerometer
Radio transmitters for Bluetooth, WiFi and cellular (3G, GSM and EDGE) signals
Proximity sensor, which likely produces near-infrared light and measures its reflection from nearby objects
16 GB or 32 GB of storage space (older iPhones could store 8 GB or 16 GB of data)
The front surface of the Apple iPhone has only one button -- the Home button. Pressing the Home button takes you to the main screen of the iPhone's graphical user interface. There, you can choose from the device's four primary functions using icons at the bottom of the phone:
Phone: 3G, GSM or EDGE cellular phone service as well as a visual voice mail menu
Mail: POP and IMAP e-mail access, including in-line pictures, HTML capabilities and push e-mail from Yahoo mail
Web: Safari Web browser
iPod: Music and videos
You can open the iPhone's other applications from the upper portion of the Home screen. These include a calendar, calculator, notepad, and widgets, or mini-applications made specifically for the iPhone. Older iPhones include a 2.0-megapixel camera and software you can use to organize your pictures -- the iPhone 3GS ups the stakes with a 3.2-megapixel camera. You can also use an iPhone to check weather reports and stock quotes. Even though the iPhone doesn't support Flash, which the YouTube site relies on, you can watch YouTube videos using the corresponding application. The keys and buttons you need to navigate each application appear only when you need them.
The shape of the screen changes when you need it to as well -- you can shift the perspective from vertical to horizontal by tilting the phone. An accelerometer inside the iPhone lets the operating system know to change the orientation of the image on the screen. This means that you can scroll through long lists of music files on a long, narrow screen, and you can watch movies in a widescreen format. You can learn more about accelerometers in How the Nike +iPod Works and How the Wii Works.
The second generation of the iPhone introduced several new features. We'll take a closer look at those in the next section.
3G iPhone Applications and Problems
Customers in Hong Kong wait in line to buy the 3G iPhone.
In June 2008, Steve Jobs unveiled the 3G iPhone at a conference for application developers. Apple offers 8 GB and a 16 GB options. The new phone's appearance only changed a little bit -- the new model has a slightly sleeker design and its back isn't silver any more. Customers who buy the 16 GB model can choose between an iPhone with a black or white plastic back. The 8 GB model only comes in black.
Perhaps the biggest announcement -- apart from the fact that the phone could take advantage of 3G network technology -- was that the new iPhone has a GPS receiver. One of the challenges of GPS devices is that they tend to drain batteries pretty quickly. That's because the device is constantly receiving signals from satellites orbiting the Earth.
Apples to Apples
Why does Apple call the second generation of iPhones the 3G iPhone? It's because the new iPhone can take advantage of the 3G cellular network. So the phone is in its second generation, but the network is in its third. The United States has a fairly limited 3G network, so U.S. citizens might not be able to tap into the faster speeds even if they buy the 3G iPhone.
Another important addition to the iPhone was support for Microsoft Exchange. Microsoft Exchange support means users can now synchronize their iPhones with their Microsoft Outlook accounts. By adding this feature, the iPhone becomes more competitive with other enterprise smartphones -- the phones businesses use to keep executives and employees connected when out of the office.
When it released the original iPhone, Apple didn't support third-party applications, though that didn't stop developers from writing them. But with the original iPhone, in order to even run a non-Apple application, an iPhone owner had to first jailbreak his or her phone. Jailbreaking just means the owner could load and run third party applications. But it came with a risk -- if you tried to install official updates from Apple with a jailbroken phone, Apple could tell that some hanky panky was going on. But the 3G iPhone acts as an application platform, and Apple encourages developers to create content for it.
Trouble in the Background
Although Apple now encourages developers to create applications for the iPhone, the company still doesn't let any outside application access background processes. That means you have to run a program actively to take advantage of it. If you switch to a different program, all activity on the first program will stop. Apple may support third party background applications in the future.
The transfer to the 3G iPhone didn't go without a hitch. Instead of allowing customers to purchase phones and activate them at home, Apple wanted them to activate the phones inside the store. Unfortunately, Apple's systems suffered an overload, causing massive delays during the product launch. Most customers ended up having to activate at home anyway.
Some of the new applications take advantage of the iPhone's accelerometer feature. Games like Super MonkeyBall let the player control the game character by tilting the phone in different ways. Could the iPhone become the next portable gaming platform? That's precisely what Apple claimed at its Sept. 9, 2009, press event. That brings us up to the current generation iPhone: the 3GS.
The iPhone 3GS
App Controversy
To get an application into the iTunes App store, Apple must approve it first. Apple retains the right to deny any application that duplicates or damages the features of the iPhone. This has led to controversy -- in 2009, the FCC stepped in to investigate claims that Apple rejected Google Voice applications unfairly.
Apple unveiled the iPhone 3GS at the 2009 World Wide Developers Conference (WWDC). The S stands for "speed." According to Apple, the iPhone 3GS is up to twice as fast as the previous iPhone 3G model. That applies both to accessing the data network and launching applications. In real-world tests, journalists found that the iPhone 3GS often was more effective at picking up 3G signals from the cell phone carrier.
But the iPhone 3GS isn't just faster than previous models. It also boasts some new features. Here's a rundown of what you can expect to find on the latest model of the iPhone:
More storage space: There are two versions of the iPhone 3GS: 16 GB and 32 GB models. This doubles the capacity of older iPhone models. Both models are available in white or black.
Video camera: Not only does the iPhone 3GS's camera capture larger photos (3.2 megapixels versus the iPhone 3G's 2.0 megapixel camera), it can record video at 30 frames per second, too. The camera can focus automatically or you can use the touch-screen to tell the camera where to focus the image. It also adjusts the image's white balance automatically.
Voice control: While many other phones on the market have voice dialing features, the iPhone 3GS's voice control extends the functionality to other parts of the phone. Not only can you make calls by speaking into your phone, you can also control music playback and other functions.
Compass: When paired with the accelerometer and GPS receiver, the iPhone 3GS's compass helps keep iPhone owners from getting lost. It also allows app developers the opportunity to develop augmented reality applications.
Oleophobic screen: One problem with touch-screens is that they tend to attract smudges. The iPhone 3GS has an oleophobic screen. An oleophobic material repels oils, keeping the screen relatively smudge-free.
Tethering: If your cell phone carrier allows it, you can use the iPhone 3GS as a modem for your computer. Simply hook the iPhone 3GS to the computer using an Apple USBcord and you can surf the Web at 3G speeds. Some carriers don't allow tethering, including AT&T in the United States.
These features sound impressive, but many of them already exist on other smartphones. We'll explore the iPhone's competition and its pros and cons in the next section.
iPhone Prices and Competition
Apple iPhone vs. Cisco iPhone
When Apple announced the iPhone in January 2007, it quickly got the attention of computer technology company Cisco. Cisco was already using the iPhone name on a range of VOIP products and services. Cisco filed a lawsuit, but the two companies eventually reached an agreement with undisclosed terms in February 2007. The agreement allows both companies to use the iPhone name.
The iPhone has gotten a lot of attention in the press, but other phone models already have similar features. Several phones now run on Android, the mobile operating system designed by Google. The Palm Pre is the first phone to use Palm's new OS called WebOS. Numerous smartphones have a built-in Opera Web browser designed for mobile devices. Although most other phones don't have completely virtual controls, some, like the Helio Ocean, have multiple physical keyboards. You can slide the front portion of the Ocean vertically to access a number pad or horizontally to access a QWERTY keyboard. The orientation of the images on the screen changes depending on which keyboard you are using. Other phones, like the Samsung Instinct, the LG Prada and the HTC Touch phone, use touch-screens and virtual controls much the way the iPhone does.
In some cases, Apple's iPhone received more attention for what it couldn't do than its wide range of features. Until June 2009, the iPhone was incapable of using cut and paste. And then, on Sept. 25, 2009, Apple rolled out multimedia message (MMS) support to its users. You can find both of these features on other phones -- MMS is common even on regular cell phones. Why did it take so long for Apple to support these basic features? There's no clear answer, though one theory is that because iPhone owners utilize their data plans more than the average smartphone user they make a significant impact on their carrier's network. As the iPhone gets more features, it puts a heavier strain on the network. It's possible that Apple is working with its carriers to avoid overloading networks with increased traffic.
The HTC Touch
At its introduction, the iPhone's price was $499 for 4 GB of storage space and $599 for 8 GB. In September 2007, Apple announced that it was lowering the price of the 8 GB model to $399 and that it would continue to sell the 4 GB model while supplies lasted. The 3G iPhone came with another drop in price: The 8 GB 3G iPhone became available for $199. Apple was able to discount the phone because phone service providers like AT&T subsidized the hardware.
The introduction of the iPhone 3GS ushered in another price cut. Now the only model of the iPhone 3G available in Apple stores is the 8 GB black phone for $99. The 16 GB iPhone 3GS is $199 while the 32 GB model is $299.
In the United States, the iPhone requires a two-year contract with AT&T, formerly known as Cingular. Unless you hack your iPhone and unlock it, it won't work at all without the AT&T plan. AT&T packages include a required data plan ($30 per month as of September 2009) that you must subscribe to and can never remove even if you decide to just use the iPhone as a normal cell phone.
The first iPhone hit the U.S. market on June 29, 2007. In the days after the release, users and reviewers criticized some of the iPhone's features, including slow browsing speeds and difficulty using the virtual keyboard. Customers reported difficulties with the lengthy activation process and itemized paper billing statements that were hundreds of pages long. Consumer-rights advocates criticized the cost of the iPhone's battery replacement program. Early iPhone adopters were also angry at the dramatic price increase -- Apple responded by offering a $100 store credit [source: APPLe]. In spite of all these difficulties, Apple sold its millionth iPhone in September 2007.
The internal display of the Nokia 6555 has more colors than you can actually see at once.
Millions of people in the United States and around the world use cellular phones. They are such great gadgets -- with a cell phone, you can talk to anyone on the planet from just about anywhere!
These days, cell phones provide an incredible array of functions, and new ones are being added at a breakneck pace. Depending on the cell-phone model, you can:
Store contact information
Make task or to-do lists
Keep track of appointments and set reminders
Use the built-in calculator for simple math
Send or receive e-mail
Get information (news, entertainment, stock quotes) from the Internet
Play games
Watch Tv
Send text messages
Integrate other devices such as PDAs, MP3 players and GPS receivers
But have you ever wondered how a cell phone works? What makes it different from a regular phone? What do all those terms like PCS, GSM, CDMA and TDMA mean? In this article, we will discuss the technology behind cell phones so that you can see how amazing they really are. If you are thinking about buying a cell phone, be sure to check out How Buying a Cell Phone Works to learn what you should know before making a purchase.
To start with, one of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio, but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo Marconi). It was only natural that these two great technologies would eventually be combined.
Cell-phone Frequencies
In the dark ages before cell phones, people who really needed mobile-communications ability installed radio telephones in their cars. In the radio-telephone system, there was one central antenna tower per city, and perhaps 25 channels available on that tower. This central antenna meant that the phone in your car needed a powerful transmitter -- big enough to transmit 40 or 50 miles (about 70 km). It also meant that not many people could use radio telephones -- there just were not enough channels.
The genius of the cellular system is the division of a city into small cells. This allows extensive frequency reuse across a city, so that millions of people can use cell phones simultaneously.
A good way to understand the sophistication of a cell phone is to compare it to a CB radio or a walkie-talkie.
Full-duplex vs. half-duplex - Both walkie-talkies and CB radios are half-duplex devices. That is, two people communicating on a CB radio use the same frequency, so only one person can talk at a time. A cell phone is a full-duplex device. That means that you use one frequency for talking and a second, separate frequency for listening. Both people on the call can talk at once.
Channels - A walkie-talkie typically has one channel, and a CB radio has 40 channels. A typical cell phone can communicate on 1,664 channels or more!
Range - A walkie-talkie can transmit about 1 mile (1.6 km) using a 0.25-watt transmitter. A CB radio, because it has much higher power, can transmit about 5 miles (8 km) using a 5-watt transmitter. Cell phones operate within cells, and they can switch cells as they move around. Cells give cell phones incredible range. Someone using a cell phone can drive hundreds of miles and maintain a conversation the entire time because of the cellular approach.
In half-duplex radio, both transmitters use the same frequency. Only one party can talk at a time.
In full-duplex radio, the two transmitters use different frequencies, so both parties can talk at the same time.
Cell phones are full-duplex.
In a typical analog cell-phone system in the United States, the cell-phone carrier receives about 800 frequencies to use across the city. The carrier chops up the city into cells. Each cell is typically sized at about 10 square miles (26 square kilometers). Cells are normally thought of as hexagons on a big hexagonal grid, like this:
Because cell phones and base stations use low-power transmitters, the same frequencies can be reused in non-adjacent cells. The two purple cells can reuse the same frequencies.
Each cell has a base station that consists of a tower and a small building containing the radio equipment. We'll get into base stations later. First, let's examine the "cells" that make up a cellular system.
Cell-phone Channels
A single cell in an analog cell-phone system uses one-seventh of the available duplex voice channels. That is, each cell (of the seven on a hexagonal grid) is using one-seventh of the available channels so it has a unique set of frequencies and there are no collisions:
A cell-phone carrier typically gets 832 radio frequencies to use in a city.
Each cell phone uses two frequencies per call -- a duplex channel -- so there are typically 395 voice channels per carrier. (The other 42 frequencies are used for control channels -- more on this later.)
Therefore, each cell has about 56 voice channels available. In other words, in any cell, 56 people can be talking on their cell phone at one time. Analog cellular systems are considered first-generation mobile technology, or 1G. With digital transmission methods (2G), the number of available channels increases. For example, a TDMA-based digital system (more on TDMA later) can carry three times as many calls as an analog system, so each cell has about 168 channels available.
Cell phones have low-power transmitters in them. Many cell phones have two signal strengths: 0.6 watts and 3 watts (for comparison, most CB radios transmit at 4 watts). The base station is also transmitting at low power. Low-power transmitters have two advantages:
The transmissions of a base station and the phones within its cell do not make it very far outside that cell. Therefore, in the figure above, both of the purple cells can reuse the same 56 frequencies. The same frequencies can be reused extensively across the city.
The power consumption of the cell phone, which is normally battery-operated, is relatively low. Low power means small batteries, and this is what has made handheld cellular phones possible.
The cellular approach requires a large number of base stations in a city of any size. A typical large city can have hundreds of towers. But because so many people are using cell phones, costs remain low per user. Each carrier in each city also runs one central office called the Mobile Telephone Switching Office (MTSO). This office handles all of the phone connections to the normal land-based phone system, and controls all of the base stations in the region.
Cell-phone Codes
Cell Phone Codes
Electronic Serial Number (ESN) - a unique 32-bit number programmed into the phone when it is manufactured
Mobile Identification Number (MIN) - a 10-digit number derived from your phone's number
System Identification Code (SID) - a unique 5-digit number that is assigned to each carrier by the FCC
While the ESN is considered a permanent part of the phone, both the MIN and SID codes are programmed into the phone when you purchase a service plan and have the phone activated.
All cell phones have special codes associated with them. These codes are used to identify the phone, the phone's owner and the service provider.
Let's say you have a cellphone, you turn it on and someone tries to call you. Here is what happens to the call:
When you first power up the phone, it listens for an SID (see sidebar) on the control channel. The control channel is a special frequency that the phone and base station use to talk to one another about things like call set-up and channel changing. If the phone cannot find any control channels to listen to, it knows it is out of range and displays a "no service" message.
When it receives the SID, the phone compares it to the SID programmed into the phone. If the SIDs match, the phone knows that the cell it is communicating with is part of its home system.
Along with the SID, the phone also transmits a registration request, and the MTSO keeps track of your phone's location in a database -- this way, the MTSO knows which cell you are in when it wants to ring your phone.
The MTSO gets the call, and it tries to find you. It looks in its database to see which cell you are in.
The MTSO picks a frequency pair that your phone will use in that cell to take the call.
The MTSO communicates with your phone over the control channel to tell it which frequencies to use, and once your phone and the tower switch on those frequencies, the call is connected. Now, you are talking by two-way radio to a friend.
As you move toward the edge of your cell, your cell's base station notes that your signal strength is diminishing. Meanwhile, the base station in the cell you are moving toward (which is listening and measuring signal strength on all frequencies, not just its own one-seventh) sees your phone's signal strength increasing. The two base stations coordinate with each other through the MTSO, and at some point, your phone gets a signal on a control channel telling it to change frequencies. This hand off switches your phone to the new cell.
As you travel, the signal is passed from cell to cell.
Let's say you're on the phone and you move from one cell to another -- but the cell you move into is covered by another service provider, not yours. Instead of dropping the call, it'll actually be handed off to the other service provider.
If the SID on the control channel does not match the SID programmed into your phone, then the phone knows it is roaming. The MTSO of the cell that you are roaming in contacts the MTSO of your home system, which then checks its database to confirm that the SID of the phone you are using is valid. Your home system verifies your phone to the local MTSO, which then tracks your phone as you move through its cells. And the amazing thing is that all of this happens within seconds.
The less amazing thing is that you may be charged insane rates for your roaming call. On most phones, the word "roam" will come up on your phone's screen when you leave your provider's coverage area and enter another's. If not, you'd better study your coverage maps carefully -- more than one person has been unpleasantly surprised by the cost of roaming. Check your service contract carefully to find out how much you're paying when you roam.
Note that if you want to roam internationally, you'll need a phone that will work both at home and abroad. Different countries use different cellular access technologies. More on those technologies later. First, let's get some background on analog cell-phone technology so we can understand how the industry has developed.
Analog Cell Phones
Old school: DynaTAC cell phone, 1983
In 1983, the analog cell-phone standard called AMPS (Advanced Mobile Phone System) was approved by the FCC and first used in Chicago. AMPS uses a range of frequencies between 824 megahertz (MHz) and 894 MHz for analog cell phones. In order to encourage competition and keep prices low, the U. S. government required the presence of two carriers in every market, known as A and B carriers. One of the carriers was normally the local-exchange carrier (LEC), a fancy way of saying the local phone company.
Carriers A and B are each assigned 832 frequencies: 790 for voice and 42 for data. A pair of frequencies (one for transmit and one for receive) is used to create one channel. The frequencies used in analog voice channels are typically 30 kHz wide -- 30 kHz was chosen as the standard size because it gives you voice quality comparable to a wired telephone.
The transmit and receive frequencies of each voice channel are separated by 45 MHz to keep them from interfering with each other. Each carrier has 395 voice channels, as well as 21 data channels to use for housekeeping activities like registration and paging.
A version of AMPS known as Narrowband Advanced Mobile Phone Service (NAMPS) incorporates some digital technology to allow the system to carry about three times as many calls as the original version. Even though it uses digital technology, it is still considered analog. AMPS and NAMPS only operate in the 800-MHz band and do not offer many of the features common in digital cellular service, such as e-mail and Web browsing.
Along Comes Digital
Digital cell phones are the second generation (2G) of cellular technology. They use the same radio technology as analog phones, but they use it in a different way. Analog systems do not fully utilize the signal between the phone and the cellular network -- analog signals cannot be compressed and manipulated as easily as a true digital signal. This is the reason why many cable companies are switching to digital -- so they can fit more channels within a given bandwidth. It is amazing how much more efficient digital systems can be.
Digital phones convert your voice into binary information (1s and 0s) and then compress it (see How Analog Recording Works for details on the conversion process). This compression allows between three and 10 digital cell-phone calls to occupy the space of a single analog call.
Many digital cellular systems rely on frequency-shift keying (FSK) to send data back and forth over AMPS. FSK uses two frequencies, one for 1s and the other for 0s, alternating rapidly between the two to send digital information between the cell tower and the phone. Clever modulation and encoding schemes are required to convert the analog information to digital, compress it and convert it back again while maintaining an acceptable level of voice quality. All of this means that digital cell phones have to contain a lot of processing power.
Let's take a good look inside a digital cell phone.
Inside a Digital Cell Phone
On a "complexity per cubic inch" scale, cell phones are some of the most intricate devices people use on a daily basis. Modern digital cell phones can process millions of calculations per second in order to compress and decompress the voice stream.
The parts of a cell phone
If you take a basic digital cell phone apart, you find that it contains just a few individual parts:
An amazing circuit board containing the brains of the phone
An antenna
A liquid crystal display (LCD)
A keyboard (not unlike the one you find in a TV remote Control)
A microphone
A speaker
A battery
The circuit board is the heart of the system. Here is one from a typical Nokia digital phone:
The front of the circuit board
The back of the circuit board
In the photos above, you see several computer chips. Let's talk about what some of the individual chips do. The analog-to-digital and digital-to-analog conversion chips translate the outgoing audio signal from analog to digital and the incoming signal from digital back to analog. You can learn more about A-to-D and D-to-A conversion and its importance to digital audio in How Compact Discs Work. The digital signal processor (DSP) is a highly customized processor designed to perform signal-manipulation calculations at high speed.
The microprocessorhandles all of the housekeeping chores for the keyboard and display, deals with command and control signaling with the base station and also coordinates the rest of the functions on the board.
The microprocessor
The ROM and Flash memory chips provide storage for the phone's operating system and customizable features, such as the phone directory. The radio frequency (RF) and power section handles power management and recharging, and also deals with the hundreds of FM channels. Finally, the RF amplifiers handle signals traveling to and from the antenna.
The display and keypad contacts
The display has grown considerably in size as the number of features in cell phones have increased. Most current phones offer built-in phone directories, calculators and games. And many of the phones incorporate some type of PDA or Web browser.
The Flash memory card on the circuit board
The Flash memory card removed
Some phones store certain information, such as the SID and MIN codes, in internal Flash memory, while others use external cards that are similar to SmartMedia cards.
The cell-phone speaker, microphone and battery backup
Cell phones have such tiny speakers and microphones that it is incredible how well most of them reproduce sound. As you can see in the picture above, the speaker is about the size of a dime and the microphone is no larger than the watch battery beside it. Speaking of the watch battery, this is used by the cell phone's internal clock chip.
What is amazing is that all of that functionality -- which only 30 years ago would have filled an entire floor of an office building -- now fits into a package that sits comfortably in the palm of your hand!
In the next section, we'll get into the cell-phone networking methods.
Cell Phone Network Technologies: 2G
There are three common technologies used by 2G cell-phone networks for transmitting information (we'll discuss 3G technologies in the 3G section):
Frequency division multiple access (FDMA)
Time division multiple access (TDMA)
Code division multiple access (CDMA)
Although these technologies sound very intimidating, you can get a good sense of how they work just by breaking down the title of each one.
The first word tells you what the access method is. The second word, division, lets you know that it splits calls based on that access method.
FDMA puts each call on a separate frequency.
TDMA assigns each call a certain portion of time on a designated frequency.
CDMA gives a unique code to each call and spreads it over the available frequencies.
The last part of each name is multiple access. This simply means that more than one user can utilize each cell.
FDMA
FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth. To better understand FDMA, think of radio stations: Each station sends its signal at a different frequency within the available band. FDMA is used mainly for analog transmission. While it is certainly capable of carrying digital information, FDMA is not considered to be an efficient method for digital transmission.
In FDMA, each phone uses a different frequency.
TDMA
TDMA is the access method used by the Electronics Industry Alliance and the Telecommunications Industry Association for Interim Standard 54 (IS-54) and Interim Standard 136 (IS-136). Using TDMA, a narrow band that is 30 kHz wide and 6.7 milliseconds long is split time-wise into three time slots.
Narrow band means "channels" in the traditional sense. Each conversation gets the radio for one-third of the time. This is possible because voice data that has been converted to digital information is compressed so that it takes up significantly less transmission space. Therefore, TDMA has three times the capacity of an analog system using the same number of channels. TDMA systems operate in either the 800-MHz (IS-54) or 1900-MHz (IS-136) frequency bands.
TDMA splits a frequency into time slots.
GSM
Unlocking Your GSM Phone
Any GSM phone can work with any SIM card, but some service providers "lock" the phone so that it will only work with their service. If your phone is locked, you can't use it with any other service provider, whether locally or overseas. You can unlock the phone using a special code -- but it's unlikely your service provider will give it to you. There are Web sites that will give you the unlock code, some for a small fee, some for free.
TDMA is also used as the access technology for Global System for Mobile Communications (GSM). However, GSM implements TDMA in a somewhat different and incompatible way from IS-136. Think of GSM and IS-136 as two different operating system that work on the same processor, like Windows and Linux both working on an Intel Pentium III. GSM systems use encryption to make phone calls more secure. GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 850-MHz and 1900-MHz (sometimes referred to as 1.9-GHz) band in the United States. It is used in digital cellular and PCS-based systems. GSM is also the basis for Integrated Digital Enhanced Network (IDEN), a popular system introduced by Motorola and used by Nextel.
GSM is the international standard in Europe, Australia and much of Asia and Africa. In covered areas, cell-phone users can buy one phone that will work anywhere where the standard is supported. To connect to the specific service providers in these different countries, GSM users simply switch subscriber identification module (SIM) cards. SIM cards are small removable disks that slip in and out of GSM cell phones. They store all the connection data and identification numbers you need to access a particular wireless service provider.
Unfortunately, the 850MHz/1900-MHz GSM phones used in the United States are not compatible with the international system. If you live in the United States and need to have cell-phone access when you're overseas, you can either buy a tri-band or quad-band GSM phone and use it both at home and when traveling or just buy a GSM 900MHz/1800MHz cell phone for traveling. You can get 900MHz/1800MHz GSM phones from Planet Omni, an online electronics firm based in California. They offer a wide selection of Nokia, Motorola and Ericsson GSM phones. They don't sell international SIM cards, however. You can pick up prepaid SIM cards for a wide range of countries at Telestial.com.
CDMA
CDMA takes an entirely different approach from TDMA. CDMA, after digitizing data, spreads it out over the entire available bandwidth. Multiple calls are overlaid on each other on the channel, with each assigned a unique sequence code. CDMA is a form of spread spectrum, which simply means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range.
In CDMA, each phone's data has a unique code.
2G is a cell phone network protocol. Click here to learn about network protocols for Smartphones.
All of the users transmit in the same wide-band chunk of spectrum. Each user's signal is spread over the entire bandwidth by a unique spreading code. At the receiver, that same unique code is used to recover the signal. Because CDMA systems need to put an accurate time-stamp on each piece of a signal, it references the GPS system for this information. Between eight and 10 separate calls can be carried in the same channel space as one analog AMPS call. CDMA technology is the basis for Interim Standard 95 (IS-95) and operates in both the 800-MHz and 1900-MHz frequency bands.
Ideally, TDMA and CDMA are transparent to each other. In practice, high-power CDMA signals raise the noise floor for TDMA receivers, and high-power TDMA signals can cause overloading and jamming of CDMA receivers.
2G is a cell phone network protocol. Click here to learn about network protocols for Smartphones.
Now let's look at the distinction between multiple-band and multiple-mode technologies.
Multi-band vs. Multi-mode Cell Phones
Dual Band vs. Dual Mode
If you travel a lot, you will probably want to look for phones that offer multiple bands, multiple modes or both. Let's take a look at each of these options:
Multiple band - A phone that has multiple-band capability can switch frequencies. For example, a dual-band TDMA phone could use TDMA services in either an 800-MHz or a 1900-MHz system. A quad-band GSM phone could use GSM service in the 850-MHz, 900-MHz, 1800-MHz or 1900-MHz band.
Multiple mode - In cell phones, "mode" refers to the type of transmission technology used. So, a phone that supported AMPS and TDMA could switch back and forth as needed. It's important that one of the modes is AMPS -- this gives you analog service if you are in an area that doesn't have digital support.
Multiple band/Multiple mode - The best of both worlds allows you to switch between frequency bands and transmission modes as needed.
Changing bands or modes is done automatically by phones that support these options. Usually the phone will have a default option set, such as 1900-MHz TDMA, and will try to connect at that frequency with that technology first. If it supports dual bands, it will switch to 800 MHz if it cannot connect at 1900 MHz. And if the phone supports more than one mode, it will try the digital mode(s) first, then switch to analog.
You can find both dual-mode and tri-mode phones. The term "tri-mode" can be deceptive. It may mean that the phone supports two digital technologies, such as CDMA and TDMA, as well as analog. In that case, it is a true tri-mode phone. But it can also mean that it supports one digital technology in two bands and also offers analog support. A popular version of the tri-mode type of phone for people who do a lot of international traveling has GSM service in the 900-MHz band for Europe and Asia and the 1900-MHz band for the United States, in addition to the analog service. Technically, this is a dual-mode phone, and one of those modes (GSM) supports two bands.
In the next section, we'll take a look at 3G mobile-phone technology.
Cellular vs. PCS
Personal Communications Services (PCS) is a wireless phone service very similar to cellular phone service, but with an emphasis on personal service and extended mobility. The term "PCS" is often used in place of "digital cellular," but true PCS means that other services like paging, caller ID and e-mail are bundled into the service.
While cellular was originally created for use in cars, PCS was designed from the ground up for greater user mobility. PCS has smaller cells and therefore requires a larger number of antennas to cover a geographic area. PCS phones use frequencies between 1.85 and 1.99 GHz (1850 MHz to 1990 MHz).
Technically, cellular systems in the United States operate in the 824-MHz to 894-MHz frequency bands; PCS operates in the 1850-MHz to 1990-MHz bands. And while it is based on TDMA, PCS has 200-kHz channel spacing and eight time slots instead of the typical 30-kHz channel spacing and three time slots found in digital cellular.
Cell-phone Network Technologies: 3G
3G technology is the latest in mobile communications. 3G stands for "third generation" -- this makes analog cellular technology generation one and digital/PCS generation two. 3G technology is intended for the true multimedia cell phone -- typically called smartphones -- and features increased bandwidth and transfer rates to accommodate Web-based applications and phone-based audio and video files.
Sony Ericsson V800 3G phone
3G comprises several cellular access technologies. The three most common ones as of 2005 are:
CDMA2000 - based on 2G Code Division Multiple Access (see Cellular Access Technologies)
3G networks have potential transfer speeds of up to 3 Mbps (about 15 seconds to download a 3-minute MP3 song). For comparison, the fastest 2G phones can achieve up to 144Kbps (about 8 minutes to download a 3-minute song). 3G's high data rates are ideal for downloading information from the Internet and sending and receiving large, multimedia files. 3G phones are like mini-laptops and can accommodate broadband applications like video conferencing, receiving streaming video from the Web, sending and receiving faxes and instantly downloading e-mail messages with attachments.
Of course, none of this would be possible without those soaring towers that carry cell-phone signals from phone to phone.
3G is a cell phone network protocol. Click here to learn about network protocols for Smartphones.
Cell-phone Towers
A cell-phone tower is typically a steel pole or lattice structure that rises hundreds of feet into the air. This cell-phone tower along I-85 near Greenville, SC, is typical in the United States:
This is a modern tower with three different cell-phone providers riding on the same structure. If you look at the base of the tower, you can see that each provider has its own equipment, and you can also see how little equipment is involved today (older towers often have small buildings at the base):
Here is the equipment owned by one of the providers:
The box houses the radio transmitters and receivers that let the tower communicate with the phones. The radios connect with the antennae on the tower through a set of thick cables:
If you look closely, you will see that the tower and all of the cables and equipment at the base of the tower are heavily grounded. For example, the plate in this shot with the green wires bolting onto it is a solid copper grounding plate:
One sure sign that multiple providers share this tower is the amazing five-way latch on the gate. Any one of five people can unlock this gate to get in.
Cell-phone towers come in all shapes and sizes, but I do believe this one in Morrisville, North Carolina, is one of the weirdest looking.
That is one tall, ugly tree!
Like all consumer electronics, cell phones come with their share of problems. In the next section, we'll take a look at some of the issues facing cell phones.
Problems with Cell Phones
A cell phone, like any other electronic device, has its problems:
Generally, non-repairable internal corrosion of parts results if you get the phone wet or use wet hands to push the buttons. Consider a protective case. If the phone does get wet, be sure it is totally dry before you switch it on so you can try to avoid damaging internal parts.
Extreme heat in a car can damage the battery or the cell-phone electronics. Extreme cold may cause a momentary loss of the screen display.
Analog cell phones suffer from a problem known as "cloning." A phone is "cloned" when someone steals its ID numbers and is able to make fraudulent calls on the owner's account.
Here is how cloning occurs: When your phone makes a call, it transmits the ESN and MIN to the network at the beginning of the call. The MIN/ESN pair is a unique tag for your phone -- this is how the phone company knows who to bill for the call. When your phone transmits its MIN/ESN pair, it is possible for nefarious sorts to listen (with a scanner) and capture the pair. With the right equipment, it is fairly easy to modify another phone so that it contains your MIN/ESN pair, which allows the nefarious individual to make calls on your account.
