Patent attributes
Random Access (RA) formats are defined for NB-IoT operation in TDD mode. The formats are defined to allow use of the legacy LTE subframe configurations for TDD. The formats specify a predetermined, even number P of symbol groups composing a RA preamble, wherein each symbol group comprises a Cyclic Prefix (CP) and a number X of symbols. The P symbol groups are divided into symbol group sets fitting into 1, or 2, or 3 contiguous uplink subframes, each comprising at least two symbol groups transmitted back-to-back (i.e., contiguously in time), and at least two symbol group sets are transmitted non-contiguously in time across a number of uplink subframes over which the RA preamble is transmitted. The number of symbol groups in a set can be two or three, and the number of symbol groups is four or six, respectively. Symbol groups within a set are transmitted on adjacent uplink subframes. Five format options are defined, which map to various of the LTE TDD configurations.
