CDMA占用的载频上行和下行各为（）

A.TURBO编码
B.香农编码
C.卷积编码
D.SBC子带编码

A.originationmessage→BSACK→TCHpreamble→Channelassignmentmessage→BSACK→MSACK→ServiceConnectmessage→Serviceconnectcompletion→assignmentcomplete
B.originationmessage→BSACK→ServiceConnectmessage→TCHpreamble→BSACK→MSACK→Channelassignmentmessage→Serviceconnectcompletion→assignmentcomplete
C.originationmessage→BSACK→Channelassignmentmessage→TCHpreamble→BSACK→MSACK→ServiceConnectmessage→Serviceconnectcompletion→assignmentcomplete
D.OriginationMessage→CMServiceRequest→TchPreamble→Establish→AssignmentComplete→Allocation；

A.软切换
B.硬切换
C.不一定