Baseband is type of transmission that is using current to send signal over the wire as digital wave. It can transmit only one signal at a time, due to requirement of the exclusive use of the wire. This type of transmission is allowing only on device to transmit in the network at one time, while other devices need to wait for the end of transmission.
While in some cases baseband supports full-duplexing, in most cases the half-duplexing is used for sending signals upstream and downstream.
Ethernet is using baseband for LANs. If the data is needed to be send to a server, network interface card is making request to use the wire. While the wire is busy, NIC retries its request. When the wire is available, the data is being sent. The process takes milliseconds and is not noticeable by user.
Broadband is using analog signal that is modulated. It is used to transmit cable TV to premises. Broadband is using different frequencies which increases amount of data it can carry at one time. The amount of data is higher 25 times compared to the baseband. Usually broadband is transmitting data in one direction, towards user. If user needs to send data, an individual channel is used for data and special amplifiers are used for data separation. While broadband signal can travel longer distances it is having additional expenses due to the use of extra equipment.
