Large cell support for narrowband random access

摘要

Aspects of the present disclosure provide techniques and apparatus for performing narrowband physical random access channel (PRACH) procedures in large cells. For example, aspects of the present disclosure provide techniques for narrowband PRACH procedures (e.g., narrowband internet of things (NB-IoT)) to accommodate larger RTTs (e.g., up to 100 km). In some cases, supporting larger RTTs may involve a base station altering its PRACH processing by performing a two-step process of, first, obtaining a frequency domain phase offset based on an uplink signal from a UE, which provides a fractional delay and, second, performing a time domain correlation for different timing hypotheses to determine a timing offset based on the uplink signal. Supporting larger RTTs may also involve enabling a new NPRACH format that may coexist with legacy 3.75 kHz resources.