Even though many mobile and wireless devices are available, there will be many more in the future.
There is no precise classification of such devices, by size, shape, weight, or computing power. Currently laptops are considered the upper end of the mobile device range.
The following list gives some examples of mobile and wireless devices graded by increasing performance that is CPU, memory, display, input devices…
However there is no sharp line between the categories and companies tend to invent more and more categories.
Sensor: A very simple wireless device is represented by a sensor transmitting state information. One example could be a switch sensing the office door. If the door is closed the switch transmit to the mobile phone inside the office which will not accept incoming calls. Without user interaction the semantics of a closed door is applied to phone call.
Embedded Controllers: Many appliances already contain a simple or more complex controller. Keyboard, headset, washing machine, coffee machine and TV are just some examples.
Why not have the hair dryer as a simple mobile and wireless devices. That is able to communicate with the mobile phone? Then the dryer would switch as soon as the phone starts ringing. That would be a nice application.
Pager: As a very simple receiver a pager can only display short text message, has a tiny display, and cannot sent any message. Pagers can even be integrated into watches. The tremendous success of mobile phones has made the pager virtually redundant in many countries. Short message have replaced paging. The situation is someone what different for emergency services where it may be necessary to page a larger number of users reliably within short time.
Mobile Phones: The traditional mobile phone only had a simple black and white text display and could send/receive voice or short message. Today Mobile phone migrates more and more towards PDAs. Mobile phone with full color graphics display, touch screen, and internet browsers are easily available.
Personal Digital Assistant: Personal Digital Assistant or PDA typically accompany a user and offer simple versions of office software. The typical input devices are a pen, with built-in character recognition translating hand writing into character. Web browsers and many other software packages are available for these devices.
Pocket computer: The next step towards full computers is pocket computers offering tiny keyboards, color displays, and simple version of programs found on desktop computers
Notebook/laptop: Finally, laptop offer more or less the same performance as standard desktop computers; they use the same software- the only technical difference being size, weight and the ability to run on a battery. If operated mainly via a sensitive display that is touch sensitive or electromagnetic. These devices are also known as notepads or tablet PCs.
The mobile and wireless devices projects of the future will be more powerful, less heavy, and comprise new interfaces to the user and to new network. However one big problem, which has not yet been solved, is the energy supply. The more features that are built into a devices, the more power it needs. The higher the performance of the devices, the faster it drains the batteries. Furthermore, wireless data transmission consumes a lot of energy.