 Transmission speeds and capacity are another challenge as traffic growth is soon expected to exceed wireless network abilities. Self-organising Networks As discussed above, broadband service provision in the NGNs will be through several differ- ent coexisting technologies. This is illustrated in Figure 13.24. The technology landscape includes 3G and 4G mobile as well as wireless LAN standards. Network configuration will TD-LTE-A LTE-A HSPA+ Femtocell TD-LTE Figure 13.24 Service delivery over heterogeneous networks Network Topologies, Design and Convergence also include from large cell to small cell. Traffic is routed through the best positioned base station or access point. A cost function is constructed for each user based on their profile and service level agreement. This function is used to find the optimal method of packet delivery to/from user equipment [19]. Clearly handover issues are complex as a mobile device travels through the coverage area. Fast handover is required especially for delay-sensitive services such as voice or streaming audio and video. More complex is network planning as different entities may own and operate parts of the network and coordination may not be practical. New networks designs are expected to be self-configuring, self-optimising and self-healing. That is, initially umbrella cover macro base stations are installed within an overall plan. Further addition of smaller cells requires little planning as these cells are designed to be self- configuring in that they communicate with neighbouring base stations and dynamically allo- cate resources to minimise mutual interference. The new cell configurations then self-optimise, in that their signal coverage is coordinated together to minimise areas of overlap and insuffi- cient received power. This reduces the requirement for drive testing and saves transmission power. Furthermore, as offered traffic to the area varies, self-optimisation allows base station load sharing and load balancing. This also allows for self-healing when one cell