1. An alternative solution to the cellular system is the walkie-talkie systems which provides a direct link between the mobile terminals. Compare the two systems.

In the cellular phone system, wireless communication is achieved through relaying communication between the cell phones through dedicated transceivers (the cellular radio tower/base station), each of which is responsible for a land area called a cell. The cell tower provides the network coverage necessary for voice and data and can pass the connection off seamlessly to the next cell tower in the case the receiver is moving between cells.

In the walkie talkie system, wireless communication is directly achieved between two transceivers through radio communication (transmitting and receiving) between the devices. Typically, walkie talkies can only either transmit or receive at a time, utilizing a “push to talk” button to toggle into transmit mode. Transmission is achieved through radio waves, and therefore the ability to maintain successful communication between two walkie talkies is determined by a distance limit between the radio transceivers.

Comparing the two systems:

• The cellular system is indirect, relaying through towers, while walkie talkies are direct communication.
• The cellular system allows for higher capacity of transmission because the same frequency can be used to maintain multiple links in different cells. As a contrast, walkie talkies can only maintain one link per frequency at a given time.
• Devices using the cellular system dissipate less power because they are transmitting and receiving a shorter distance, solely to the nearest cell tower. By contrast, walkie talkies transmit the full power to transmit and receive their maximum specified distance.
• The cellular system has allowed for larger coverage areas because more cell towers can be added indefinitely, leading to cellular coverage which is contiguous and widespread. Walkie talkie coverage is limited by the spatial distance of the transmitter and receiver.
• Because walkie talkies do not rely on cell towers, they are more useful for communication in rural/empty areas.
• Walkie talkies transmit at a lower frequency (short range radio), therefore they are less disrupted by the surroundings, such as trees, buildings, etc.

1. Amplifier with Two Dependent Sources: The amplifier model below...