 the number of calls per carrier to about 25. The cdmaOne system archi- tecture supports multiple carriers in one system, 11 in the North American PCS band. The multiple carriers of a large cdmaOne system are treated as a single resource in channel assignment. The wireless telephone system selects an available carrier for each channel at the start of a call, and the system can instruct the user terminal to change to a different carrier during handoff, performing a carrier-to-carrier handoff. For both voice and data service, one large single resource is more efficient for traffic gineering than several small resources, as discussed in Chap. 21. 10.1.4 cdmaOne forward channel coding The cdmaOne forward channel takes the RS1 voice signal, 0.8 to 8.55 kbps, and adds frame, quality, and overhead information to bring it to 1.2, 2.4, 4.8, or 9.6 kbps. This is doubled by convolutional forward error correction (FEC) to 2.4, 4.8, 9.6, or 19.2 kbps. The lower bit rates are simply repeated to generate a speech-coded and forward-error- corrected stream of 19.2 kbps. RS2 uses a less aggressive forward error correction scheme, 4 to 3 instead of 2 to 1, so its full 13-kbps rate still comes out to 19.2 kbps. This stream goes through a block interleaver so that bursty errors in the channel do not become adjacent errors in the bit stream. The bits are multiplied by a long pseudo- noise (PN) code specific to the wireless call. Eight hundred power-control bits per sec- ond are sent on a subchannel created by puncturing the 19.2-kbps data stream. Each 24-bit power-control group has 2 bits replaced with a power-control bit. The position of the power-control bit in the 24 bits is one of the first 16 bits based on the last 4 bits of the last power-control group. Each voice channel is assigned one of 64 orthogonal Walsh codes so that the 19,200 bits per second are spread to 1.2288 Mbps. These bits are then spread once more by the short PN code into in-phase and quadrature signals. The pilot is sent at a high power level, transmitting all 