Introduction: Team chopsticks, Ziqiu Li, Charles Shearer, Andrew Spahr Technology Selected

Our team chose cell phone technology due to its increasing role in our society. We all use cell phones but we don’t really understand how they work. Our goal is to shed some light on how the cell phone works and technology uses. We will take it from infancy to its current’s technology state. We will explain the components of the phone, the equipment, the phone talks to and the medium it uses. We chose this technology due to the fact that is it has such a wide use in our society. It has evolved from a large bulky mobile car phone to a complex multimedia device that can be as small as a credit card. It has the ability to send and receive voice, data, pictures, text, video and many other forms of multimedia. To start off, cell phone is basically a radio. We going to explain what is a cell phone, how it works, and who uses it. Cell phone technology is advancing in a rapid pace, we all uses it in business, socializing, and for multi-media, and for downloading data. Companies like Verizon, sprint, T-mobile, sony, and many more have built the infrastructure in phones, completing international switching stations in cellular grids enabling us to communicate uninterrupted. The technology used is part computer chip, circuit board, radio frequency, digital cellular tower, switching stations, and human interaction. It is gone from 1G to 3G in terms of stages. Currently, we are entering the 3G, third generation, of technology of expanding our communication abilities. Let’s take a look at how the cell phone has evolved.

The concept of the cell phone began in 1947. They were originally intended to be mobile car phones that could reuse frequencies traveling before small cell ranges. They were actually radio telephones. These early mobile phones were actually introduced to automobiles first, and were half duplex in nature, thus meaning they can only carry one way communication at a time. For example, policeman utilizing the radio could send his message and would have to wait for the reply to be return to him on another frequency. At that time, there was only one tower per city with only about 25 channels available on that tower. That meant that the phone in your car had to have a powerful transmitter that could reach 40 to 50 miles. Obviously not too many people could use the radio telephones; there were not enough channels. In 1968, the Federal Communication Commission (FCC) reconsidered its position in increased the elocution of frequencies. Dr. Martin Cooper, a manager from Motorola considered being the inventor of first portable handset and he made first call on the phone on 1973. At that time, bell laboratories introduced cell technology in police cars. However, Motorola was the first company to design cell phone for use outside of automobile. In the late 70s, Bell labs constructed first proto types of cellular systems. Tokyo, Japan soon followed. That brings to us today.

This is a cell phone circuit board containing the digital analog processor, the digital signal processor, the ROM, flash memory and the RF amplifiers.

To explain a little bit of the background and history of the cell phone; we will introduce you to one of pioneers of the technology. Dr Martin Cooper, a former general manager for the systems division at Motorola, is considered the inventor of the first modern portable handset. Cooper made the first call on a portable cell phone in April 1973. He made the call to his rival, Joel Engel, Bell Labs head of research. Bell Laboratories introduced the idea of cellular communications in 1947 with the police car technology. However, Motorola was the first to incorporate the technology into portable device that was designed for outside of an automobile use. Cooper and his co-inventors are listed above. By 1977, AT&T and Bell Labs had constructed a prototype cellular system. A year later, public trials of the new system were started in Chicago with over 2000 trial customers. In 1979, in a separate venture, the first commercial cellular telephone system began operation in Tokyo. In 1981, Motorola and American Radio telephone started a second U.S. cellular radio-telephone system test in the Washington/Baltimore area. By 1982, the slow-moving FCC finally authorized commercial cellular service for the USA. A year later, the first American commercial analog cellular service or AMPS (Advanced Mobile Phone Service) was made available in Chicago by Ameritech.

Despite the incredible demand, it took cellular phone service 37 years to become commercially available in the United States. Consumer demand quickly outstripped the 1982



Dr. Martin Cooper

Let’s compare a cell phone with other forms of radio communication. Take the walkie talkie and the CB radio as examples. They use what is referred to as half duplex technology. Where two people use the same frequency allowing only one person to talk at a time. The walkie talkie uses one channel. The CB radio uses 40 channels. A cell phone can use up to 1664 channels or more. The walkie talkie can transmit approximately one mile and the CB radio about five miles. The cell phone can cross multiple cellular grids and continue to hold its signal. Today cell phones utilize full duplex technology (2G, 3G) and cellular grids carrying multiple frequencies allowing multiple users to carry multiple conversations at any moment. With the advancement of the digital technology, these frequencies are broken down into even more channels allowing compression of the signal, and greater switching frequency. 3G technologies basically is the utilization and expansion of the digital technology comprising multimedia, data voice, video, games, television, internet, message, music, and any other PED (personal digital assistance).

Quite simply put the cell phone is a radio utilizing its frequencies to carry voice, data, and relaying data between cellular areas. The genius of the cell phone is that the cities are broken up into small cells. This allows extensive reuse of the frequencies across the city. This led to first generation (1G) terminology to classify the initial analog cell phones. This analog technology used the 800 MHz frequency range in each city. Now to better understand cells, consider a city broken into 10 mile areas, these areas are the boundary of the cells, and within these cells service and carrier acquire multiple frequencies to broadcast. Within these cells there is a base station (picture) and radio equipment; T1.

As a note, the following information is recently published regarding analog cell phone service. If you're one of those slow adopters who like to keep your old cellular phone around, it's finally time to ditch it for a newer model.

Let’s look at how the carrier communicates with our phones. Carrier utilizes the frequencies within the cell by central switching office. The central switching office is a landline base station controlled by the carrier. All the towers, cellular carriers owns our managed through the central switching office. Now, the carrier utilizes frequencies within the cellular areas to communicate, control, the data and voice with the phone call. The central switching office maintains a data base containing all the base stations at the towers, who in turn contain all of the frequencies. Now when the central switching office needs to contact a particular cellular grid during the flow of a phone call, it contacts a base station which contacts the cellular phone via the control chip, and the control frequency within the cell. This base station identifies the phone via System Identification Code (SID) in your phone. The SID is a unique five digit number that’s assigned to each carrier by the Federal Communication Commission (FCC). This SID coupled with electronic serial number (ESN), which is a unique number that is programmed in your phone when it’s manufactured. For example, we powered the phone; it listens for the SID on the control channel, which is broadcast on the control frequency from the base station. What happens here is the base station and your phone now communicate channel changing, frequency to be used, and any other unique identifiers. Now your phone will receive the SID, and compare to the ones that has inside, if the SIDs match, then it knows it is talking to its home carrier. Now here is the interesting part. Once the SID has identified to the home network, it will now transmit to the Mobile Telephone Switching Office (MTSO). The MTSO keeps track of your phone’s location and its data base. This is how your MTSO knows which cell you are in, and can ring your phone. Now in the mean time, the MTSO has turned on the frequency in the tower in your cellular area and locked it to your phone and your call is connected. As you travel and move, remember cellular grids are about 10 miles radius from tower to tower, at this time, your MTSO is constantly tracking you, knowing when to switch to another tower.

There are also multi mode cell phones meaning dual band and dual mode cell phone technology. These refer to cell phones that have multiple band capability. The multi band type of cell phone can utilize frequencies between 800 MHz all the way through 1900 MHz range. The multi mode cell phone can use different transmission types. They use AMPS or TDMA transmission types and switch between them if needed. These cell phones are generally good when travelling in different areas of the world. In Europe and Asia they use the 900 MHz frequency and in the U.S. we use the 1900 MHz range. These cell phones can switch automatically when needed.

With all of these switching power used in digital technology (2G, 3G), these phones require a lot of processing power. Let’s take a look at the guts of the digital cell phone. They are some of the most intricate devices we use. They process millions of calculations per second to compress, decompress switch the voice, data, moves, music, and all the other multimedia tasks we require doing. There really are only a few parts which makes its design more impressive. The parts to make up the phone are:

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  Circuit board containing the brains of the phone
  
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  Antenna
  
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  LCD
  
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  Keypad
  
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  Microphone
  
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  Speaker
  
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  Battery
  

We as a group have learned great deal about how our cell phones that we rely on really work. We have learned that they are actually radios processing digitized, compressed, video, images, voice, data and satellite signals. We now understand as we travel how our cell phone communicates across multiple cellular grids and constant contact with the MTSO. We have attempted to explain what it is, how it works, and obviously we all use it. We feel this technology is only going to explode in the future. We know we will be able to use our phones for everything from buying food, gas to contain our accounts, personal IDs.

Charles Shearer: Research and Narration

Ziqui Li: Filming; Video editing

Andrew Sphar: Statistics and planning