Sign in Subscribe

5G NR Grant Free Dynamic Scheduling

Last updated on 


The 5G New Radio (NR) Grant-Free Dynamic Scheduling is a feature in the 5G wireless communication standard that allows devices to transmit data without explicit scheduling from the network. This is particularly useful in scenarios where devices have sporadic or sporadically predictable data to send, such as in the case of Internet of Things (IoT) devices with occasional sensor data to transmit.

Here's a technical breakdown of how 5G NR Grant-Free Dynamic Scheduling works:

  1. Device Monitoring:
    • Devices continuously monitor the wireless channel for opportunities to transmit data.
    • They may use techniques like energy detection or listen-before-talk to assess the channel's availability.
  2. Channel Access Opportunities:
    • The wireless channel is divided into different time-frequency resources, known as Resource Blocks (RBs).
    • The device identifies available RBs where it can potentially transmit without causing interference to other devices.
  3. Initial Access:
    • When a device has data to send, it can access the channel without prior scheduling by the network.
    • The device utilizes a predefined set of resources known as preamble formats to initiate communication.
  4. Random Access Channel (RACH):
    • The device uses a Random Access Channel to transmit a preamble to the base station without prior coordination.
    • The preamble is a short burst of data that helps the base station identify the device and estimate the channel conditions.
  5. Preamble Detection:
    • The base station continuously monitors the RACH for incoming preambles.
    • When a preamble is detected, the base station estimates the channel conditions and decodes the device identity.
  6. Contention Resolution:
    • In case multiple devices access the channel simultaneously and cause contention, a contention resolution process is initiated.
    • The base station may use techniques like contention-based random access to resolve conflicts among devices contending for the same resources.
  7. Data Transmission:
    • Once the base station successfully identifies and resolves contention for a device, it assigns the device a set of resources for data transmission.
    • The device can then use these allocated resources to transmit its data.
  8. Scheduling Request:
    • If the device requires more resources or needs to transmit additional data, it can send a scheduling request to the base station.
    • The scheduling request helps the network allocate additional resources for the device.
  9. Benefits:
    • Grant-free dynamic scheduling improves the efficiency of communication by allowing devices to transmit data when needed without waiting for explicit scheduling from the network.
    • It is particularly beneficial for low-latency and sporadic communication scenarios, such as IoT applications.