s and Management Wi-Fi systems did not become a universal infrastructure layer technology for a number of reasons. One was the inherent short range of communications due to usage of the CSMA-CA resource allocation technique. Moreover, higher transmission rates were possible over short ranges: no performance advantage existed on comparable distances of a few kilometres typical of GSM/CDMA macro cells. Rolling out of a large number of small cells presented other challenges: each Wi-Fi access point needed to connect to a fixed network through an optical fibre link. Such connections were not readily available and the cost of rolling out an optical fibre backhaul was generally prohibitively large, as illustrated in Figure 12.7. Latest technologies facilitate a network roll-out topology where only a fraction of the access points need a fixed line connection. The remaining access points can connect to these using wireless links. This topology is at times referred to as multi-hop or mesh networking as broadband traffic hops over several access points until it reaches an access point which is connected to fixed backhaul. For example only a subset of all access points in Figure 12.7 are connected to the backhaul network by wire (those Figure 12.7 A typical city-wide wireless LAN roll-out (Adelaide) Personal Wireless Communications Systems shown in lighter grey). The rest of the access points connect to these, and to the back- haul network wirelessly. A number of municipalities have rolled out Wi-Fi networks to provide coverage over their central business districts. Many such municipal wireless networks exist: from Johannesburg, to Hong Kong, to Adelaide, to San Francisco. However, most of these systems have been publicly funded, and most have failed to produce sufficient revenue to cover their operating costs. As a result, many cities have stopped their free Wi-Fi services. A number of cities have turned to a public-private partnership in order to roll out and continue operating city-wide Wi-Fi networks. Adelaide City Coun