 ATM domain. All packet data gets terminated locally; thus, packet data transfer between switch sites does not exist Table 7.32 Inter Switch Site Traffic (E1s) for 2002 and 2005 MSC MSC MGW MGW City A-city B 1 STM-1 City B-city C 1 STM-1 City C-city A 1 STM-1 Total 3 STM-1 7.10.3.5 Local Switch Site Traffic The traffic flow in the local switch sites corresponds to the interface load between UMTS nodes at the switch sites. Values in Table 7.33 include all overheads as well as load factors, ready to get mapped onto the payload of the physical PDH/SDH/Ethernet links. Values in Table 7.33 reflect total figures. Table 7.33 Local Switch Traffic for 2002 and 2005 Local switch traffic Inter- City A City B City B (Mbps) UTRAN RNC RNC- MGW MGW-GGSN MGW-PSTN (external network) GGSN-ISP (external network) MGW-other switch sites MGW-MSC-S (sign) MGW-SGSN-S (sign) SGSN-S-GGSN (sign) CO-LOCATING AND SHARING SITES With the widespread use of the 2G mobile network (e.g. GSM), by the time we start deploying UMTS most countries or regions will have already at least one 2G mobile system in operation. While in some places restrictions for new sites will not affect 3G network deployment, in others this will become a key factor to maximize re-use of sites and push site sharing to the limits. In Switzerland for example, regulations on power levels, cost of sites and environmental protection regulations do make it difficult to ac- quire new sites. Thus, co-locating 2G and 3G equipment becomes imperative. To ad- dress these issues in the following we illustrate co-location primarily with UMTS and GSM-1800 MHz. Deploying 3G Networks Site sharing depends on the relative coverage of the existing network when compared to UTRA-FDD19. Here we compare at the relative UL coverage of GSM1800 with full-rate speech service and WCDMA speech and 144 kbps data service. Table 7.34 illustrates the basic assumptions and reference results. Table 7.34 Common Path Losses GSM1800 MHz and UTRA-FDD GSM1800/ WCDMA/ WCDMA/ speech speech 144 kbps Mobile transmissio