Resource Blocks in LTE?

In LTE, the eNodeB (eNB) is responsible for allocating Resource Blocks (RBs) to User Equipment (UEs) dynamically based on network conditions, QoS requirements, and scheduling algorithms.

What is a Resource Block (RB)?

·         The smallest unit of resource allocation in LTE.

·         Contains 12 subcarriers in frequency and lasts for 1 slot (0.5 ms) in time.

·         Used for data transmission and control signaling.

·         LTE operates in FDD or TDD mode, where RBs are assigned separately for uplink (UL) and downlink (DL).

Resource Block Allocation Process in LTE

1.       UE Requests Resources

• UE sends a Scheduling Request (SR) via PUCCH or a Buffer Status Report (BSR) if it has data to transmit.

2.       eNodeB Scheduler Allocates RBs

• The eNodeB MAC scheduler determines the number of RBs based on:
• CQI (Channel Quality Indicator) from UE
• QoS Requirements (GBR, MBR, priority)
• Network load and interference levels

3.       Downlink (DL) Resource Allocation

• eNB assigns RBs via DCI (Downlink Control Information) sent over PDCCH.
• UE decodes the DCI format to know which RBs are assigned.

4.       Uplink (UL) Resource Allocation

• eNB assigns RBs for UL via PDCCH and UL Grant.
• UE transmits data using assigned RBs over PUSCH.

5.       HARQ & Adaptive Scheduling

• If data is not received correctly, HARQ retransmissions occur.
• eNB dynamically adjusts RB allocation every TTI (1 ms).