Cellular Communications

From Isopedia

1 Historical Information
2 Technical Information
3 Sources
4 Team Members

Historical Information

It has taken 59 years of development to reach the capabilities cell phones have today. The concept of cellular phones was first introduced in 1947 when researchers working for Motorola came to the realization that the traffic capacity of crude mobile car phones could be increased substantially by using small cells with frequency reuse. However, at this time the FCC or Federal Communications Commission decided to limit the amount of frequencies available, so the development of a cell phone for the public slowed down.

In 1968, the FCC finally came around and released a statement saying, “If the technology to build a better mobile service works, we will increase the frequencies allocation, freeing the airwaves for more mobile phones.” Researchers at both Motorola and AT&T/Bell Labs were in constant competition to see who would be the first to develop a cellular handset. In 1973, Dr. Martin Cooper of Motorola made the first call on a portable cellular phone and an era was born. In 1977, public trials began in Chicago with 2000 phones. Finally, in 1982, the FCC approved the commercial cellular service.

Cellular communications has shaped modern society. It has changed the way the world thinks not only on a business level but also on a personal level. Without cellular communications, today’s society would be significantly less productive.

Technical Information

By definition, a cell is considered the basic geographical unit of the overall “cellular system”. The shape of the coverage area that cell towers reach to is termed cellular due to the fact that it resembles the shape of a honeycomb (Cells are hexagon shaped). Just like there are software and mechanical engineers, there are also cellular engineers who decide the placement of cell towers, and the type of range each will cover. This is to make sure that the most efficient use of the frequencies is accomplished. In order for the cell systerms to work companies had to devise a way to reuse cell frequencies. They accomplished this by having cells with the same frequency, but not within the same cluster. They accomplished this by having the cells far enough away that the frequencies would not interfere with each other. With the popularity of cell phones increasing engineers developed the concept of “cell splitting”. Cell splitting is a way of splitting each cell into smaller ones, so that they can accommodate for heavily populated regions by delivering good service levels. Of course, the next dilemma for engineers was something they described as the “handoff”. Engineers came up with a way to deal with one person’s movement between cells. The process of handoff occurs when the mobile telephone network transfer a call from one radio channel to another as the user crosses a cell. Of course, simply dropping the call would have been unacceptable.

The mobile telephone switching office handles all the handoffs and is typically the center of cell phone operation. Though, its uses are not limited to just controlling handoffs. The mobile telephone switching center also tracks billing information, locates cellular users, and controls calls. The cell cites need this center for operation.

In its earliest stages cell phones and towers were analog. The next phase of cellular systems was Frequency-division multiple access, or FDMA. It accomplished the sharing of a frequency by allocating users to different ends of the spectrum. This system has now been replaced by digital systems. One of the advantages of this new digital system is that fact that it can hold up to six calls per channel, where analog could only hold one. Digital technology architecture advances such as TDMA (Time division multiple access) have been installed in most cellular areas and have advantages such as increasing capacity and security. There are other systems similar to TDMA that have helped shape and evolve the cellular communications industry. Systems engineered such as the E-TDMA, and (Extended TDMA) CDMA (Code division multiple access) have since increased capacity up to 15 times of the original analog engineering by operating under algorithms. Techniques such as this have helped pave the way for new uses of cellular communications such as computers using wireless access, besides the general person to person call.