AMPS (Advanced Mobile Phone System)

Introduction:

The Advanced Mobile Phone System (AMPS) was one of the first analog cellular systems deployed in the United States. AMPS was launched commercially in the United States in 1983 and was in use until 2008, when the Federal Communications Commission (FCC) officially ended its use. AMPS was designed as a second-generation (2G) mobile phone system, and it laid the foundation for many of the cellular systems used today.

History:

AMPS was developed by Bell Labs in the 1970s and was first demonstrated in 1978. The system was designed to replace the first-generation mobile phone systems, which were very expensive and had limited coverage. AMPS was the first cellular system to be deployed on a large scale, and it quickly became the most popular mobile phone system in the United States.

AMPS System Architecture:

AMPS was designed to use a frequency-division multiple access (FDMA) system, which means that each call is assigned a specific frequency band. The system uses two frequency bands: the uplink frequency band (mobile-to-base) and the downlink frequency band (base-to-mobile). Each band has 832 frequencies, and each frequency is 30 kHz wide. This means that there are a total of 1664 frequencies available for AMPS.

AMPS uses a cell-based architecture, where each cell is served by a base station. The cells are hexagonal in shape, and the size of each cell depends on the number of users in the area. The base station is connected to a mobile telephone switching office (MTSO), which is responsible for controlling the call routing and management.

AMPS Call Processing:

AMPS call processing is divided into two phases: call setup and call management. Call setup is the process of establishing a call between the mobile phone and the base station, and call management is the process of maintaining the call.

Call Setup:

When a mobile phone is turned on, it searches for the strongest signal from a nearby base station. Once it finds a base station, it sends a request for service to the MTSO. The MTSO then determines the appropriate base station to connect the call to and sends a signal to the mobile phone to tune into that frequency.

Once the mobile phone is tuned into the appropriate frequency, it sends a signal to the base station to request a channel. The base station then assigns a frequency to the mobile phone, and the call setup is complete.

Call Management:

Once the call is established, call management is responsible for maintaining the call. This includes monitoring the signal strength, managing handoffs between cells, and managing any call features, such as call waiting or call forwarding.

AMPS Call Features:

AMPS has several call features, including call waiting, call forwarding, three-way calling, and call hold. These features are implemented using a signaling channel, which is separate from the voice channel.

Call Waiting:

When a user is on a call and receives another call, the AMPS system uses a signaling channel to alert the user of the incoming call. The user can then choose to ignore the call or put the current call on hold and answer the incoming call.

Call Forwarding:

Call forwarding allows a user to forward incoming calls to another phone number. This feature is implemented by programming the user's mobile phone number into the MTSO database, and any incoming calls are forwarded to that number.

Three-Way Calling:

Three-way calling allows a user to add a third party to a call. This feature is implemented by using the signaling channel to request a second channel, and the MTSO then connects the third party to the call.

Call Hold:

Call hold allows a user to put a call on hold and then resume the call at a later time. This feature is implemented using the signaling channel to request a hold on the call, and the MTSO then places the call on hold until the user is ready to resume the call.

AMPS Limitations:

AMPS was a significant step forward in mobile phone technology, but it had several limitations. One of the biggest limitations was its analog nature, which made it susceptible to interference and limited the number of users that could be on the system at the same time.

Another limitation was its limited data capabilities, which made it unsuitable for transmitting digital data such as email or web pages. AMPS also had limited security features, which made it vulnerable to eavesdropping and unauthorized access.

AMPS Legacy:

Despite its limitations, AMPS laid the foundation for modern cellular technology. AMPS was the first cellular system to be deployed on a large scale, and it set the stage for the development of newer, more advanced cellular systems.

The success of AMPS also paved the way for the development of other mobile phone technologies, such as digital cellular systems like GSM and CDMA, and the adoption of cellular technology around the world.

Conclusion:

The Advanced Mobile Phone System (AMPS) was one of the first analog cellular systems deployed in the United States. AMPS was designed as a second-generation (2G) mobile phone system, and it laid the foundation for many of the cellular systems used today. AMPS used a frequency-division multiple access (FDMA) system and had a cell-based architecture. AMPS had several call features, including call waiting, call forwarding, three-way calling, and call hold. AMPS had several limitations, including its analog nature, limited data capabilities, and limited security features. Despite its limitations, AMPS paved the way for modern cellular technology and the adoption of cellular technology around the world.