One of the biggest differences between 5G and 4G is the reference to numerology. The so-called parameter set can be understood as 4G only uses one set of parameters, so the parameters in the frame structure, including subcarrier spacing, SCS), time slots, symbols and other parameters, are a set in all environments, which will have great limitations. 5G introduces the concept of parameter set, and selects different parameter sets for different environments, which greatly increases the flexibility of communication.

The parameter settings are as follows:

△f stands for subcarrier spacing, which is fixed at 15KHz in 4G and can support up to 480KHz in 5G (some companies put forward 75KHz subcarrier spacing in the process of formulating standards, and 6G may be included in the discussion in the future). There are two types of cyclic prefixes, one is common and the other is extended. Under normal CP, the time slot includes 14 OFDM symbols, while the extended CP includes 12 OFDM symbols. Among them, the extended CP only appears when the subcarrier interval is 60KHz.

The frame structure is as follows:

The time of 1 frame is still Tf = 10ms, and it is divided into 10 subframes numbered #0~#9, and the time of each subframe is Tsf = 1ms, and the number of OFDM symbols contained in a time slot is 14, and each symbol number is #.

The first table and the second table correspond to the parameter relations in the case of normal CP and extended CP respectively. The column 1 indicates different parameter set labels, the fourth column indicates the number of time slots contained in each subframe under different parameter sets, the third column indicates the number of time slots contained in a frame, and the second column indicates the number of symbols in each time slot.

At the same time, 5G supports more slot formats, as shown below:

Where D stands for downlink, UL stands for uplink, and X stands for flexibility, it can be seen that the time slot format of 5G has better flexibility, such as the full uplink configuration in 10 format when uplink transmission is busy.

Like 4G, the physical resources of 5G are mapped on the time-frequency resource grid. As shown in the figure below, when the physical layer performs resource mapping, the time-frequency resource element re) is taken as the basic unit, and a RE consists of a symbol in the time domain and a subcarrier in the frequency domain. All 0FDM symbols in a time slot and 12 subcarriers in the frequency domain form a resource block RB), and the position of the RE is represented by (k, l), representing (represented by lamenda in the figure), and k represents 0f. By giving the coordinates (k, l), you can locate on the specified RE.