The PHICH, or Physical Hybrid ARQ Indicator Channel, in LTE has the role of carrying HARQ ACK/NACK responses for PUSCH. It provides the feedback from the network to the UE about the success or failure of the reception of an uplink data transmission. If the uplink data sent by the UE is correctly received by the base station (eNodeB), the PHICH will carry an ACK (acknowledgment). If the data is not correctly received, the PHICH will carry a NACK (negative acknowledgment), prompting the UE to retransmit the data using the Hybrid Automatic Repeat Request (HARQ) process. This mechanism is essential for ensuring reliable data transmission in LTE networks.

Further Readings

• PCFICH