ll rights reserved. Any use is subject to the Terms of Use as given at the website. Subscriber Traffic Modeling Subscriber Traffic Modeling Not only do we have to consider interference from neighboring cells, we have to con- sider interference from neighboring sectors on the same cell. Because the interferers in these cases are so close, we have to consider each bin separately rather than treat the entire interfering cell or sector as a single source of radio power, as we could do in con- ventional reuse. The blocking-rate calculation in CDMA is also different from conventional reuse. The CDMA air interface works best when each user terminal is served by the antenna face with the highest radio path gain, so there is no need for complex traffic overflow mod- els. However, CDMA has soft blocking (described in Sec. 30.6), where the capacity of each CDMA carrier depends on the utilization of its neighbors. This is a kind of load sharing that changes the traffic engineering calculations in favor of using higher occu- pancy for the same blocking rate. A single server with 20 channels can support 13.2 erlangs of traffic at 2 percent blocking. However, a cdmaOne system, limited to 20 channels per carrier by intercell and intersector interference, can support 15.6 erlangs of traffic per carrier at the same 2 percent blocking. If a single carrier had all its neighboring cells and sectors continu- ously serving 20 users, then it would be limited to 13.2 erlangs for 2 percent blocking. However, having an average load of 15.6 erlangs on all the cell sectors, the system is essentially sharing the CDMA air interface. A CDMA traffic-planning tool must take soft blocking into account. Another important CDMA traffic issue is pilot pollution, where nearly equal radio paths degrade CDMA capacity, as described in Sec. 32.1. The CDMA planning tool must calculate the loss of capacity from having multiple cell sectors competing with each other while sharing a CDMA carrier. Time division duplex (TDD), as used in time division synchronize