 handoffs. Not all CDMA handoffs are soft handoffs. Sometimes the pilots of the two cells are too different for the mobile telephone to synchronize them. Some vendors permit soft handoffs from one MSC to another, but the ANSI-41 handoff standards in Sec. 15.1 do not require it. cdmaOne supports having multiple CDMA carrier frequencies to make the best use of more than 1.25 MHz of radio bandwidth. Handoffs under any of these conditions can be the old-fashioned AMPS-or-GSM-style handoffs that we call hard handoffs in CDMA. Handoff support requires signal coordination within the cellular network, as described in Sec. 11.4. 8.8 The Forward (Downlink) Direction The forward link from base station to user terminal has one base station sending a common radio signal to many user terminals, a one-to-many radio environment. This offers the opportunity to share broadcast resources and to synchronize signals. Having a one-to-many environment allows for a strong pilot signal for each receiver to use for coherent modulation and rake filter alignment. Carrier phase and multipath change rapidly for mobile and portable telephones and slowly for fixed wireless local loop. The synchronization of all the signals allows orthogonal codes to be used to minimize interference. So long as the delay spread is not much longer than the chip duration, the same-sector interference can be reduced significantly. On the negative side of the forward link, the common path for signal and interfer- ence means that the rake filter does as good a job coherently amplifying interferers as it does coherently amplifying the signal. The optimal receiver is matched to the delay spread of the signal. If the delay spread of the interferer is the same as the signal, then it is going to give each interferer the same advantage. The Reverse (Uplink) Direction The reverse direction of CDMA from user terminal to base station has many user ter- minals sending signals to a single receiving antenna at the base station, a many-to-one radio environment. While synchronizat