Why there is no PHICH & PCFICH channels in 5G?

The two channels PHICH and PCFICH which are present in LTE but are not required in NR.

PHICH channel is used in LTE to handle uplink re-transmissions and are tightly coupled to use of synchronous hybrid-ARQ protocol, but as the HARQ protocol is asynchronous in NR in both downlink as well as uplink.

Hence the PHICH is not required in NR.

Also as the size of the CORESERTs does not vary dynamically and reuse of control resources for data is handled in a different way than it is done in LTE, thus the PCFICH is not necessary in NR.

Unlike LTE there is no PCFICH in 5G as PCFICH gives information about PDCCH OFDM symbol in time domain and in frequency domain, there is no need to specify as it spreads across whole channel bandwidth.

But in 5G, frequency region should be specific, and It can be signaled by RRC signaling message.

We have different IE indications for LTE and NR for PDCCH/DCI.

Source: Puliraju Mulinti on LinkedIn: #all #5g #interview #technology #5g