The MAC sublayer of NB-IoT divides a variety of logical channel types according to the type of information transmitted and provides different transmission services for different data services. According to the type of information transmitted on each channel, logical channels are divided into control channels and traffic channels. Two categories.GPRS-модуль The control channel is responsible for transmitting information on the control plane. The control channels provided by the MAC sublayer mainly include the following types:(1) Broadcast Control Channel (BCCH) is used to broadcast downlink information of system control information.(2) The paging control channel (Paging Control Channel, PCCH) is a downlink channel used to transmit paging information. When the network side does not have information about the cell where the UE is located, this channel is used to page the terminal.(3) Common Control Channel (Common Control Channel, CCCH) When there is no C connection between the UE and the network, this channel is used to transmit control information between the UE and the network. It is an up-and-down bidirectional channel(4) Dedicated Control Channel (Dedicated Control Channel, DCCH) When there is an RRC connection between the UE and the network, this channel is used to transmit dedicated control information between the UE and the network, which is point-to-point bidirectional information. GPRS ДТУ The traffic channel provided by the MAN sublayer is a dedicated traffic channel (Dedicated Traffic Channel, DTCH), which is a point-to-point traffic transmission channel for a single UE, which can be unidirectional or bidirectional. The traffic channel is responsible for transmitting the information of the user plane. NB-IoT UEs that only support CP mode does not support DTCH.