:: Wireless Modems

The wireless service is an alternative to the cable internet service for data networks.

The advantage wireless offers is the geographic reach and coverage and the lower cost associated with this coverage. The provisioning of a cable service is contingent on finding a region with a dense subscriber base. The cost of laying a cable network in a region is also considerable. In semi-rural and rural areas, both DSL and cable services can have limited presence. Here wireless services can offer a better alternative. Wireless may also be better suited to business and institutional customers requiring high speed. It can deliver upto 30 Mbps in a 6 MHz channel. Wireless services however do suffer from other limitations. The network is expensive to install and it has ‘line-of-sight’ limitations. A receiving antenna and a downconverter are also required to be installed on the building or on the window of your unit.

In a wireless modem, the Internet signal is converted by a 64 – QAM modulator to a 44 MHz intermediate frequency signal and sent to the transmitter. This signal occupies a 6 MHz bandwidth. The customer receives the line of sight signal into his wireless ‘cable’ modem, which in turn is connected to the computer through an Ethernet card. Each 6 MHz channel can support around 90000 subscribers. The return signal uses QPSK technology and a different path to reach the Internet Gateway and the downstream transmitter. More often the return path is achieved through other channels such as the telephone or ISDN.