 13.8 FUNDAMENTAL PLANS IN ACCESS NETWORKS The access part is designed according to plans that primarily reside in the connectivity layer, with licenses for frequencies and rules for synchronization methods, transmission Understanding Changing Telecommunications - Building a Successful Telecom Business Wide area network Mobility coverage Local area network Vehicle performance Wideband cellular Personal area network - cable replacement Fixed Bluetooth Mbps (data rate) Figure 13.17 Positioning of wireless techniques systems and multiplexing/aggregation. However, there is a need for support from many other fundamental plans. For example, it should be recalled that security and QoS in fact are involved at all layers. Further, access nodes might need numbering and simple routing functionality. Certainly, a good management system is required. 13.9 MOBILITY The large added value of mobile systems is of course the mobility. This parameter varies widely between different system solutions. See Figure 13.17. The coverage also corre- sponds to a degree of mobility. 13.10 ACCESS TECHNOLOGIES IN MOBILE NETWORKS There are different technology standards available for access to a mobile system: FDMA, TDMA and CDMA. The main characteristics are illustrated in Figure 13.18. 128 bits chip/bit Figure 13.18 Access methods Access Network 13.10.1 FREQUENCY DIVISION MULTIPLE ACCESS (FDMA) FDMA is common in the first generation mobile communication systems, the analogue systems. One physical channel is allocated per subscriber and is used during the entire duration of the call. The channel is unavailable for other subscribers during that time. The physical channel is released at the end of the call and is then available for the next subscriber. 13.10.2 TIME DIVISION MULTIPLE ACCESS (TDMA) TDMA is the most common technology in the second generation of mobile communication systems, the digital systems. The available spectrum in TDMA is divided into physical channels of equal bandwidth. See Figure 13.19. The subscriber is allocated a time sl