In this chapter, we will review the underlying mechanisms for the evolution of wireless communication networks. We will first discuss macro-cellular technologies used in traditional telecommunication systems, and then introduce some micro-cellular technologies as a recent advance in the telecommunications industry. Finally, we will describe existing interworking techniques available in literature and in standardization, including loosely and tightly coupled, I-WLAN and IEEE 802.21.

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... r Technologies The term macro-cell is used to describe cells with larger sizes. A macro-cell is a cell in mobile phone networks that provide radio coverage served by a high power cellular base station. The antennas for macro-cells are mounted on ground-based masts and other existing structures, at a height that provides a clear view over the surrounding buildings and terrain. Macro-cell base stations have power outputs of typically tens of watts [18]. Most wireless communication systems maintained by traditional mobile network operators are powered by macro-cellular technologies. 1G/2G/3G Networks In the 1980s, the 1G wireless communication system came to the mobile communication environment, which provided a data speed of 2.4 Kbps to support data communication with mobile phones. An example is Nordic Mobile Telephone (NMT). However, this generation still worked in analog system and there were tight limitations in terms of the system capacity and data rate.