Question

A Hybrid Fiber-Coaxial (HFC) network has a bandwidth that ranges from 5 to 750 MHz. Describe the purposes of the three bands in this bandwidth.

Answer 1

The Hybrid Fiber-coaxial cable has a bandwidth that ranges from 5 to 750 MHz. To provide Internet access, the cable company has divided this bandwidth into three bands. Those are Video, Downstream data and Upstream data.

Purposes of each band are mentioned below :

• The Video band occupies frequencies from 54 to 550 MHz. Generally each TV channel occupies 6 MHz, Video band can accommodate more than 80 channels. Video content was sent only to the home.
• The downstream signals carry information from the headend office to the home, such as video content, voice and Internet data.
• The upstream signals carry information from the home to the headend office, such as control signals to order a movie or Internet data to send an email.

Both upstream and downstream bands are shared by the subscribers. The upstream data bandwidth is 37 MHz. This means that there are only 6-MHz channels available in the upstream direction. A subscriber needs to use one channel to send data in the upstream direction.
   (The bandwidth divided into channels. These channels must be shared between subscribers in the same neighborhood. The cable provider allocates one channel, statically or dynamically, for a group of subscribers. If one subscriber wants to send data, they contends for the channel with others who wants access, the subscriber must wait until the channel is available.)
   we have the similar situation in the downstream direction. The downstream band has 33 channels of 6 MHz. Here we have a multi casting situation. Each subscriber also has an address registered with the provider. The cable modem for the group matches the address carried with the data to the address assigned by the provider. If the address matches, the data are kept; otherwise, they are discarded.