 were using directional A = 4/3 T antennas in the RNs, which point to the outside of the cell. This is especially useful to reduce SDM intracell interference. In contrast, Figure 8.18 shows TDM with omnidirectional antennas. Compared to the directional antennas, we observe a bigger area covered by the RNs at the edge of the inner hexagon. Results without antenna gain (G0) between the BS and RN are not shown graphically, but they are shown numerically in Table 8.2. The main points about the parameters are that an antenna gain (G14) for the stationary first-hop link should be possible; directional RN antennas trade off less area near the center against more area between RNs, but the spectral efficiency does not change much; and using the SDM resource reuse among RNs, we gain a lot of capacity, especially in the coverage scenarios. C 2009 by Taylor & Francis Group, LLC Multihop Extensions to Cellular Networks Figure 8.26 Map and bounding area of the Jersey scenario. The BS and RN are marked red. 8.5.4 Realistic Single-Cell Scenario Now we come to a more realistic scenario for the use of fixed relay nodes. The city of Jersey was taken, with its geographical and building structure, and realistic path loss maps were simulated by ray tracing and used in this analysis [25]. Compared to the previous abstract and regular cellular scenarios, this provides a good proof of concept. Jersey has been chosen for this scenario because the area of approximately 4.439 km2 is a typical cell size. By using a radio network planning tool, base sta- tions and all relay nodes are placed at the best possible locations (see Figure 8.26). The relays are either fed by the BS (set RNHI) or by a RN out of RNHI (set RNH2). Thus, there are one-hop, two-hop, and three-hop links between the BS and UTs. The topology (building placement) was known in advance, and ray tracing tools have been used to obtain the received signal power PR, at each location from each possible transmitter site. The physical parameters and calculation steps have been given i