iPhone 4S

The screen size remains the same, the quality of the display however couldn't be more different.

Apple has developed something they call the Retina Display for the iPhone 4. Basically they took the old display and made the pixels far smaller. This enabled them to fit four times the pixels on the display which makes the picture quality far superior to the older 3GS.

In other words the iPhone 4 has same sized screen as its predecessor but its display boasts 4 times the picture quality.

iPhone 3G and iPhone 3GS screen are not same in size. handypart.com

The most recent mobile network standards bring more speed and greater reliability to mobile devices. Mobile networks were always slower than broadband and dropped the connections frequently. With 4G LTE technology, that has changed. Mobile Telecommunications Group GSMA publishes information about LTE. The eventual goal is to make super-fast and highly reliable connectivity available anywhere for all mobile devices and computers.

Today's mobile technology comes from cell phone networks. These systems achieved mobility by placing radio transmitters and receivers in grids throughout cities and along major highways. The operating range of a transmitter/receiver was called a cell. Cell phones used the transmitter/receiver of the cell where they were located to make calls, and used different cells as they moved.

The cell phone networks were slow because each cell phone had to find a clear frequency for its signal and change cells as it moved. When there was static and phones had to re-transmit data, or when there were delays in finding a new cell, the cell phone dropped the call or had poor sound quality.

With the third-generation 3G networks, many of these problems were solved by increasing the speed at which mobile phones connected. Phones using 3G technology could re-send failed transmissions and connect to new cells fast enough that voice quality didn't suffer. Data transmission speeds were still slow. Devices using networks operating on 4G standards archive extremely fast data transmission speeds as well.

The International Telecommunication Union (ITU) has defined standards for 4G mobile networks that include a download speed of 1.5 Gbps. Agilent Technologies has some of the details. This speed translates into being able to download even the largest emails, social network posts, photographs and YouTube videos in a fraction of a second. Mobile devices will be bale to stream HD video while remaining connected to other services. While there are several technologies that may eventually achieve this speed, there are no true 4G public networks in operation at the moment.

An accurate name for 4G LTE technologyis 4G candidate LTE. LTE stands for Long Term Evolution and it is an evolving technology that eventually plans to achieve true 4G speeds and become an accepted 4G standard. At its development level in 2012, it is a candidate for the 4G mobile network standard, but operates at speeds of about 100 Mbps. To give you some idea of what is in store for these networks, this present speed is faster than broadband connections but it's only one tenth of the final projected speed of the 4G network.

LTE technology has three operating advantages and a development advantage over competing technologies. On the operating side, it transmits and receives data very quickly, makes quick connections when changing cells, and it doesn't drop connections. On the development side, the name gives the advantage. It is an evolving technology. That means it is compatible with previous generations of mobile network technology and future versions will be compatible with today's 4G LTE networks. Service providers have not broadly adopted other technologies that are candidates for 4G acceptance because they represent technical breaks from existing networks.

LTE networks achieve their higher speeds in two ways. They use existing bandwidth more efficiently than older technologies, and they transmit and receive via multiple inputs and outputs. Both these methods of increasing speeds are evolutionary, but the idea of using multiple transmission paths lends itself to increasing the speed by multiplying the number of paths. This means that older, slower devices can operate on the same network as newer, faster ones. The older units simply operate at slower speeds because they use fewer paths, while the latest devices download data via many more channels and achieve a much higher speed.

For example, when someone using a 4G LTE tablet wants to send an email, they tap the "send" button and the tablet looks for the best way to transmit the data. It has several antennas optimized for different frequencies, and it sends data packets on multiple paths simultaneously. It then checks with the network whether the data has arrived. The tablet stops using paths which result in corrupted data or lost data packets, continues to use the good connections, and initiates new connections to replace faulty ones. In addition to allowing data transmission at high speeds through multiple paths, the multiple connections make it unikely that the device will drop a call.

The advantages of 4G LTE are compelling enough that many mobile operators around the world have chosen to expand their networks with this technology. Much development work remains to be done. Operating multiple signal paths uses a lot of power, and mobile devices will need larger batteries unless the technology becomes more efficient. Operating multiple antennas in a compact space is a difficult design challenge, and the software to reconstruct the signals quickly at the receiving end is complex. While promising comparatively high data transmission speeds and increased reliability in the short term, the ability of 4G LTE to become a true 4G service is not yet established.