ea. Spectrum The 4G systems are expected to provide bandwidths higher than 20 Mbps and to accommodate a signif- icantly increased amount of traffic, SO sufficient frequency resources will be required. Since the lower frequency band considered suitable for mobile communications is heavily used, a frequency band for the 4G communications is to be proposed in the 3G to 5G bands. Cell Radius As planned, the bandwidth to be offered in 4G systems is three orders of magnitude greater than that of 2G systems. The cell radius covered by a base station (BS) generally decreases if, assuming all other conditions to be the same, radio signals are transmitted at higher bit rates than at a lower transmission bit rate in order to compensate for the increased noise level. Moreover, 4G systems may be operated in Fourth Generation Mobile Networks a higher frequency band SO that propagation loss of the wireless signal is higher than that of 2G and 3G systems. Using a complex set of equations, the increase in propagation loss caused by the operating frequency and channel speed can be converted into a decrease in cell radius (assuming the antenna height to be 23 m) if other transmission conditions are assumed to be the same as those of 3G systems. This means that by covering the same area as in 3G systems, the 4G systems will require four times the number of BSs. The antenna height of the BS in an urban area tends to be lower when the cell size is smaller. As result, there may be more outage areas, even within the calculated cell radius, and it is observed that one solution to enhance the capacity is to decrease the cell radius of the BS. Hierarchical Service Area Although all objects will be connected to a network through wireless links, it may be difficult for small devices to be directly connected to 4G systems due to power consumption and antenna size. Compact devices will be able to access the 4G systems through a miniature base that will act as a mobile terminal (MT) for 4G systems. Employing such a configuration results in serv