Smartphones use cellular radio technology in conjunction with specially designed processors. App developers have discovered new and inventive ways to use hardware and wireless connectivity to make information instantly available to users as smartphones have evolved. Larger, more accurate touch displays enable multi-window computing with input from all ten fingers at the same time. Because of efficient multitasking and abundant memory, recently used apps can reside in a stack without slowing performance.
SMS, MMS, and Voice
The first mobile phones required massive batteries to transmit radio signals to towers that could be hundreds of miles away. They communicated over a relatively narrow bandwidth using 1G radio technology. Voice and SMS communication worked similarly to today, except that 2G radio technology introduced cellular towers and modern protocols such as GSM and CDMA, allowing mobile phones to use significantly less power. SMS communication is efficient over a low-bandwidth connection because messages are limited to 160 bytes, and with the introduction of 3G technology, MMS can use the same protocol to deliver multimedia messages of any size.
Input via Touch and Accelerometer
The accelerometer on a smartphone measures the amount of static or dynamic force felt by the device and provides this information to the operating system. While not all apps make use of accelerometer input, the accelerometer constantly polls the device’s current position in relation to the Earth so that apps can retrieve it when necessary. When the user interacts with the display in a specific way, most apps listen for touch input in the form of taps or gestures and execute program commands. For example, sliding your thumb across the screen slowly may not result in a page flip, but sliding it quickly results in an acceleration value high enough to flip the page.
Input from the Camera and Microphone
A smartphone’s camera takes pictures most of the time, and its microphone records your voice during a phone call. App developers have also come up with innovative ways to incorporate these input devices into useful software, such as QR code scanners and music identification services. A QR code is a digital code that looks like a bar code but contains vertical as well as horizontal information, and a QR code scanner is a function that takes a QR code as input and outputs product information, an HTTP link, or other data. A song snippet from a user’s microphone input is processed by music identification services and compared to results in a database. With high-speed wireless Internet, the user receives results from the service immediately, and she may be able to download a song or follow a QR code link in a Web browser based on these results.
3-D Video Acceleration
More complex software, such as 3-D video gaming and hardware-accelerated graphics, has become possible as smartphone processor architecture has evolved. Companies like ARM, NVIDIA, and Qualcomm manufacture powerful CPUs and integrated GPUs that support 3-D video frameworks while consuming little power. High-performance multi-core CPUs, such as the Snapdragon S3, use a compact 45nm manufacturing process to achieve high clock speeds, low power consumption, and low heat output. The majority of mid-range smartphones continue to use processors with less powerful 65nm process CPUs and less powerful video acceleration.