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5G Numerology

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5G (fifth-generation) wireless communication systems, numerology refers to the set of parameters that define the structure of the radio frames and subframes, as well as the spacing of resource elements in the frequency and time domains.

Here are the key aspects of 5G numerology:

  1. Subcarrier Spacing (Δf): One of the fundamental parameters in 5G numerology is the subcarrier spacing, denoted by Δf. It represents the frequency difference between consecutive subcarriers in the frequency domain. 5G supports multiple subcarrier spacings to cater to different use cases. The two primary subcarrier spacings are 15 kHz (for enhanced mobile broadband) and 60 kHz (for ultra-reliable low latency communication).
  2. Slot Duration (Ts): The time domain is divided into slots, and the slot duration, denoted by Ts, is a key parameter. It defines the duration of each slot in the time domain. In 5G, there are different slot durations, such as 1 ms and 0.5 ms, to support diverse applications with varying latency requirements.
  3. Frame Structure: 5G frames are organized into slots, and several slots together form a frame. The frame structure is defined by the number of slots per frame and the frame duration. Common frame durations in 5G include 10 ms and 20 ms.
  4. Numerology Index (μ): The numerology index, denoted by μ, is an integer that represents the combination of subcarrier spacing and slot duration. It is used to uniquely identify the numerology of a particular transmission. Different values of μ correspond to different combinations of subcarrier spacing and slot duration.
  5. Resource Blocks (RBs): Resource blocks are the basic units of resource allocation in the frequency and time domains. They are defined by a combination of contiguous subcarriers in the frequency domain and consecutive symbols in the time domain. The size of a resource block depends on the subcarrier spacing and slot duration.
  6. Symbol Duration (Tsymbol): The symbol duration, denoted by Tsymbol, is the time taken for one symbol transmission. It is determined by the product of the number of symbols per slot and the slot duration.
  7. Slot Structure: Each slot is further divided into a set of symbols in the time domain. The slot structure includes the number of symbols per slot and the arrangement of symbols within a slot.
  8. Cyclic Prefix (CP): The cyclic prefix is a guard interval inserted between symbols to mitigate the effects of multipath fading. The duration of the cyclic prefix is defined based on the channel conditions.