ls from multiple server groups. Multiple server groups create multiple headaches for neighbor list generation. Sup- pose that we have a cellular system laid out like Fig. 27.17. For each of the 33 cells in this picture, imagine calculating all the reasonable cells for a handoff. Now imagine taking the 57 logical faces in Fig. 27.18 and doing the same job. Remember that other logical faces on the same cell are handoff candidates as well. Now take these same two pictures and imagine all the cells are three-sector cells so that most of these cells have 5 or 6 logical faces. A large cell may have two neighbors completely covering one of its large-cell sector areas so that the total would be 5 instead of 6 logical faces. Six-sector cells with two server groups can have 12 logical faces. As you can see, the combination of faces, server groups, and logical faces can make life very difficult for a cellular engineer. This is only a 33-cell system, whereas big sys- tems have hundreds of cells, and we have not considered radio propagation irregulari- ties. Sometimes a cell's actual coverage has a pseudopod extending far enough so that the handoff neighbor list has some odd-looking entries. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Basic Wireless Telephony Basic Wireless Telephony The good news for the CDMA cellular planner is that CDMA has no need of multiple cell radii, server groups, or logical faces. 5.2.4 Individual radio channels Each sector is served by a collection of radios for individual subscriber voice and data links. These radios may be separate units, individual transceivers in a row on a radio frame, or separate logical entities in one physical box. (The distinction between physi- cal and logical models is described in Sec. 14.4.) These radios are the system's termi- nation point for the air interface. In addition to the individual 