BOTTLENECK The distributed dimension contains the expensive access part. In addition access is the bandwidth bottleneck. However, the role as a bottleneck can be reduced with new access Understanding Changing Telecommunications - Building a Successful Telecom Business Functionality & capabilities WCDMA 2 Mbps EDGE/IS-136 384 kbps 115 kbps Packet switched HSCSD 38.4 kbps Circuit switched 14.4 kbps Circuit data <9.6 kbps Speech Figure 3.43 Bandwidth evolution for GSM-type systems IEEE 802.11 Standard 802.11 1 or 2 Mbps. No interoperability 802.11b 2, 5.5 or 11 Mbps. Interoperability 802.11a Up to 54 Mbps in 5 GHz UNII band 802.11a 802.11b 802.11 Figure 3.44 WLAN access bit rates systems, such as 3G, WLAN, VDSL and later 4G. Cost of provisioning wide-area band- width is (almost) directly proportional to the bandwidth. On the other hand the willingness to pay for bandwidth is hardly proportional to the bandwidth. This is the dilemma of the access network provider. For mobile GSM-type systems the bandwidth development is given in Figure 3.43. For WLAN systems the various bit rates for some main standards are shown in Figure 3.44. A further development of 802.11b in the 2.4 GHz band (802.11g) provides up to 54 Mb/s. The WLAN technology is shown schematically in Figure 3.45. Networks and Technologies Internet or corporate network Infrastructure mode Router Ad hoc network Roaming Coverage: from tens to hundreds of metres Figure 3.45 WLAN as a LAN without wires to the left, and as an access infrastructure to the Internet to the right Table 3.2 VDSL speeds Upstream Downstream Distance 1.6-2.3 Mbit/s 13 Mbit/s 1500 m 26 Mbit/s 1000 m 52 Mbit/s 300 m 3.12.3 VDSL The fastest established technique over copper at present is the VDSL, 'Very-high-bit rate DSL'. VDSL is just as ADSL based on the use of advanced modems. For symmetric use the full bit rate is 26 Mbit/s in each direction. For asymmet- ric use there are different speeds downstream and upstream for example according to Table 3.2. 3.13 THE PROCESSING DIMENSION Ever sinc