 of the line, but let us assume that we have narrowed the complaint down to the wireless telephone system. 3 There are several links in the data chain, several opportunities for delay. Before we launch an investigation into air-interface issues, we should make sure that the packet links in our transport network are not overloading and causing delay. These links are one or more backhaul hops, the mobile switching center (MSC) packet switch, and the links from the MSC to the public packet data network (PPDN). Once we have narrowed the search for data delay down to the air interface, we know that the CDMA data channel is not sending and receiving subscriber bits quickly enough. Because the CDMA channel is a packet data link, reduced capacity means that packets have to wait in a queue before they are sent. A short period of slow data service could be a short-term radio performance issue. The wireless data terminal could be moving into an area of low radio gain, or some other subscriber could be changing radio conditions, perhaps even in another sector or another cell. The CDMA carrier may take a second or two to reach a new equilibrium. The cause of slow data service for one subscriber may be a burst of data activity from another data subscriber. If two bursty data subscribers are using the same CDMA car- rier, then there may be brief periods when they will both be requesting data and there is only room for one. Then the other will have to wait a fraction of a second. If this hap- pens only occasionally, then a subscriber might not even notice that the delay is in the CDMA system and not the data server at the other end. Sustained slow data rates are a more urgent concern. Subscribers will notice them and, over time, will become sensitive to them. Initial 3G service will be exciting and novel, and people will be anxious just to get wireless data at high speeds. However, fre- quent periods of slow service will dilute that excitement and generate a community of 1This is the worst case because all the 3G CDMA carriers h