Splitting As demand grows, each cell sector is carrying more traffic. We can represent the peak- hour traffic on each cell sector as a statistical distribution based on the average de- mand level and the mix of services. Some part of that demand distribution will be above the capacity of the cell sector. If we have engineered the system well, then it will re- spond to too much demand by blocking calls. As the demand grows, the fraction of that statistical distribution on the high side of the maximum capacity will increase, and the blocking rate will rise. The way cell splitting relieves capacity is simple. The new cell is placed amid the old cells so that it serves some of the region of the old cells and therefore serves some of the traffic. The old cells are now smaller in area and have reduced subscriber demand. The distribution of traffic is now lower as a result, and the old cells should return to an acceptable blocking rate. If two neighboring cells are overloaded, then a new cell can be placed midway between them. In some ideal sense, we would like the three cells to share equally the burden of the original two. This would reduce the average demand on the older two cells by one-third. In actual practice, the new cell initially serves less than this ideal one-third share of the total traffic. The first step of the cell-splitting process is to identify high- and medium-urgency candidates for traffic relief. These are base stations that are currently experiencing high peak-hour blocking or are going to in the near future. Like any other coverage picture in a real place with real terrain and real buildings, the new cell will be some kind of odd shape. We use a geometric construction with hexa- gons and straight lines to get a conceptual picture of what the new cell can do for ca- pacity relief. The cell sectors that have high blocking during the busy hour are in need of traffic relief. They are already telling us that our wireless telephone system needs to increase its capacity to provide adequate service. Once