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MTA (Mobile Telephony System (version A)

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Introduction

Mobile Telephony System (MTS) is an analog cellular system that was developed and deployed in the 1970s. MTS was one of the earliest cellular networks and was developed by Bell Labs in the United States. MTS used a frequency division multiple access (FDMA) scheme to provide voice communication over the wireless network. The first version of the MTS system was known as Mobile Telephony System version A (MTA). This paper will explore the MTA system in detail, including its architecture, functionality, and limitations.

MTA Architecture

The MTA system is comprised of several components that work together to provide wireless voice communication. The MTA architecture includes the following:

  1. Mobile Unit (MU) - The mobile unit is the user equipment that is used to initiate and receive calls. The MU is a portable device that includes a microphone, speaker, and keypad for dialing phone numbers.
  2. Base Station (BS) - The base station is a fixed radio transceiver that is used to transmit and receive signals to and from the mobile unit. The BS is responsible for assigning frequencies to the MU and managing the call setup process.
  3. Mobile Telephone Switching Office (MTSO) - The MTSO is a centralized switching center that is responsible for managing the communication between the MU and the PSTN (Public Switched Telephone Network). The MTSO is also responsible for managing the handover process as the MU moves from one cell to another.
  4. Public Switched Telephone Network (PSTN) - The PSTN is the traditional landline phone network that is used to route calls between different phone numbers.

MTA Functionality

The MTA system provides voice communication over the wireless network using a frequency division multiple access (FDMA) scheme. In an FDMA system, the available frequency band is divided into several channels, each of which is assigned to a single user. The MTA system operates in the 800 MHz frequency band and uses a 30 kHz channel spacing. The MTA system provides a total of 666 channels, with each channel supporting a single user.

The MTA system uses analog modulation techniques to transmit voice signals over the wireless network. The voice signal is first converted to an analog signal, which is then modulated onto a carrier frequency using either amplitude modulation (AM) or frequency modulation (FM). The modulated signal is then transmitted over the wireless network to the recipient mobile unit.

The MTA system also provides several features that were not available in the traditional landline phone network. These features include call waiting, call forwarding, and three-way calling. The MTA system also provides roaming capabilities, which allow users to make and receive calls while traveling outside of their home service area.

MTA Limitations

Despite its early success, the MTA system had several limitations that ultimately led to its demise. The primary limitation of the MTA system was its analog modulation scheme. Analog modulation is susceptible to interference from other radio signals, which can result in poor call quality and dropped calls. The MTA system also had limited capacity, as each channel could only support a single user. This limitation meant that the MTA system could not support a large number of users in a single cell.

Another limitation of the MTA system was its inability to support data communication. The MTA system was designed for voice communication only and did not support any data transfer. This limitation meant that the MTA system was not suitable for transmitting text messages or other data-based communication.

Conclusion

In conclusion, the Mobile Telephony System version A (MTA) was one of the earliest cellular networks that was developed and deployed in the 1970s. The MTA system used a frequency division multiple access (FDMA) scheme to provide voice communication over the wireless network using analog modulation techniques. The MTA system consisted of several components, including the mobile unit, base station, mobile telephone switching office, and public switched telephone network.

Despite its early success, the MTA system had several limitations, including its analog modulation scheme, limited capacity, and inability to support data communication. These limitations ultimately led to the development of newer cellular networks, such as the digital cellular network (DCN) and the Global System for Mobile Communications (GSM), which provided improved call quality, increased capacity, and support for data communication.

Today, cellular networks continue to evolve and improve, with the deployment of 5G networks and the development of new technologies such as VoLTE (Voice over LTE) and VoNR (Voice over New Radio). These advancements are enabling faster data transfer, higher quality voice calls, and support for new applications such as augmented reality and virtual reality.

In conclusion, the Mobile Telephony System version A (MTA) played an important role in the development of cellular networks and provided the foundation for the cellular networks that we use today. While the MTA system had several limitations, it paved the way for the development of newer and more advanced cellular networks that are transforming the way we communicate and connect with one another.