Why PHICH and PCFICH channel is not present in NR

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Why PHICH and PCFICH channel is not present in NR(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.

CORESET is nothing but the concept of central to downlink controlling signaling in NR. CORESET is a time frequency resource in which the device tries to decode candidate control  channels using one or more search spaces.  The PDCCH in NR does not necessarily span the full carrier bandwidth but it does in LTE PDCCH.



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