The Importance of Filters in Point-to-Point Microwave Cellular Backhaul Networks

Backhaul is the backend part of every wireless system, yet it is every bit as important as the front end portion that everyone sees. In the US, wireless backhaul has been performed using T-1 lines, as they were adequate for handling the levels of voice traffic on the network. However, thanks to 3G and the massive upsurge in data traffic it produces they are rapidly becoming obsolete. The emergence of 4G networks is further increasing this traffic load. T1s are not only inadequate for handling this traffic volume but incompatible with IPbased transmission schemes as well. There are two basic technologies that will replace them: microwave point-to-point links and fiber optics.

Although microwave links are used in more than 70% of installations throughout Europe and 50% globally, they are rarely used in the US. However, this is projected to change rapidly as point-to-point links provide an excellent solution for backhaul, especially in the and almost 80% of cases where fiber nodes are not available at the cell site. Filters are an essential components of every microwave link as they keep interference in check as they do and all wireless networks. They are typically bandpass filters that with sharp rejection characteristics, but other filter types are used as well. This white paper highlights the importance of these filters in Point-to-Point Microwave Cellular Backhaul Networks.