e systems are not commonly used mainly due to their proneness to interference but with proper use of the spread spectrum technology and network planning, interference can be mitigated. The ISM band is divided into three sub-bands at 5.15 to 5.25, 5.25 to 5.35, and 5.725 to 5.825 GHz. The first sub-band is restricted for indoor use while the remaining two can be used for microwave applications over distances in excess of 20 kilometers. 7.3.3.1 Trial We primarily tested this solution to address the shortage of traditional frequencies used for setting up microwave radio links and to minimize the use of VSAT (Very Small Aperture Terminal) systems. The trial of multiple IP-based products of multiple vendors showed that these systems are productive and can be used in some parts of the networks to address above mentioned challenges. During the trials we also witnessed the unavailability of such links during heavy rainfall [8]. The trials were conducted in one of the country's highly interference clogged areas. Three different IP-based products were tested in the same location over a period of several weeks. The key characteristics of these products are listed in Table 7.1 [8]. First, the link was established without having commercial traffic on it and we conducted some dry runs. Then, live traffic was carried on the link for few weeks and several tests were executed. During execution we verified data throughputs, frequency tuning, signal strengths, and SO on. 7.3.3.2 Trial Setup The trial architecture consists of microwave master and slave equipment which is installed at two different two GSM cell sites. The distance between the two sites was 10 km and the sites were carrying TDM traffic. In order to carry the TDM traffic via IP-based microwave systems we used TDM/IP converters at the far and near ends as shown in Figure 7.6. The whole exercise lasted for six months to cater for the needs of varying weather conditions. Table 7.1 Product features Features Product A Product B Product C Topology PMP/PtP Channel Bandwidth 1