Channel hogging and file sharing[edit]

There will be a hit to file sharing, the normal web surfer would want to look at a new web page every minute or so at 100 kbs a page loads quickly. Because of the changes to the security of wireless networks users will be unable to do huge file transfers because service providers want to reduce channel use. AT&T claimed that they would ban any of their users that they caught using peer-to-peer (P2P) file sharing applications on their 3G network. It then became apparent that it would keep any of their users from using their iTunes programs. The users would then be forced to find a Wi-Fi hotspot to be able to download files. The limits of wireless networking will not be cured by 4G, as there are too many fundamental differences between wireless networking and other means of Internet access. If wireless vendors do not realize these differences and bandwidth limits, future wireless customers will find themselves disappointed and the market may suffer setback

Future of smartphone[edit]

The next generation of smartphones are going to be context-aware, taking advantage of the growing availability of embedded physical sensors and data exchange abilities. One of the main features applying to this is that the phones will start keeping track of your personal data, but adapt to anticipate the information you will need based on your intentions. There will be all-new applications coming out with the new phones, one of which is an X-Ray device that reveals information about any location at which you point your phone. One thing companies are developing software to take advantage of more accurate location-sensing data. How they described it was as wanting to make the phone a virtual mouse able to click the real world. An example of this is where you can point the phone's camera while having the live feed open and it will show text with the building and saving the location of the building for use in the future.

Along with the future of a smart phone comes the future of another device. Omnitouch is a device in which applications can be viewed and used on your hand, arm, wall, desk, or any other everyday surface. The device uses a sensor touch interface, which enables the user to access all the functions through the use of finger touch. It was developed at Carnegie Mellon University. This device uses a projector and camera that is worn on the person's shoulder, with no controls other than the user's fingers.

A comparison of mobile phone standards can be done in many ways.

Global System for Mobile Communications (GSM, around 80–85% market share) and IS-95 (around 10–15% market share) were the two most prevalent 2G mobile communication technologies in 2007.[1] In 3G, the most prevalent technology was UMTS with CDMA-2000 in close contention.

All radio access technologies have to solve the same problems: to divide the finite RF spectrum among multiple users as efficiently as possible. GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM.

• Time-division multiple access (TDMA) provides multiuser access by chopping up the channel into sequential time slices. Each user of the channel takes turns to transmit and receive signals. In reality, only one person is actually using the channel at a specific moment. This is analogous to time-sharing on a large computer server.

• Frequency-division multiple access (FDMA) provides multiuser access by separating the used frequencies. This is used in GSM to separate cells, which then use TDMA to separate users within the cell.

• Code-division multiple access (CDMA) This uses a digital modulation called spread spectrum which spreads the voice data over a very wide channel in pseudorandom fashion using a user or cell specific pseudorandom code. The receiver undoes the randomization to collect the bits together and produce the original data. As the codes are pseudorandom and selected in such a way as to cause minimal interference to one another, multiple users can talk at the same time and multiple cells can share the same frequency. This causes an added signal noise forcing all users to use more power, which in exchange decreases cell range and battery life.

• Orthogonal Frequency Division Multiple Access (OFDMA) uses bundling of multiple small frequency bands that are orthogonal to one another to provide for separation of users. The users are multiplexed in the frequency domain by allocating specific sub-bands to individual users. This is often enhanced by also performing TDMA and changing the allocation periodically so that different users get different sub-bands at different times.

In theory, CDMA, TDMA and FDMA have exactly the same spectral efficiency but practically, each has its own challenges – power control in the case of CDMA, timing in the case of TDMA, and frequency generation/filtering in the case of FDMA.

For a classic example for understanding the fundamental difference of TDMA and CDMA, imagine a cocktail party where couples are talking to each other in a single room. The room represents the available bandwidth:

TDMA: A speaker takes turns talking to a listener. The speaker talks for a short time and then stops to let another couple talk. There is never more than one speaker talking in the room, no one has to worry about two conversations mixing. The drawback is that it limits the practical number of discussions in the room (bandwidth wise).

CDMA: any speaker can talk at any time; however each uses a different language. Each listener can only understand the language of their partner. As more and more couples talk, the background noise (representing the noise floor) gets louder, but because of the difference in languages, conversations do not mix. The drawback is that at some point, one cannot talk any louder. After this if the noise still rises (more people join the party/cell) the listener cannot make out what the talker is talking about without coming closer to the talker. In effect, CDMA cell coverage decreases as the number of active users increases. This is called cell breathing.