Mechanisms to Facilitate Random Access by Link-Budget-Limited Devices

摘要

Mechanisms enabling link-budget-limited (LBL) devices to more effectively perform random access may include: (1) broadcasting a Physical Random Access Channel (PRACH) configuration index (PCI) reserved for LBL devices; (2) configuring LBL devices to use a PCI that is offset from the conventional PCI of current cell; (3) configuring LBL devices to transmit PRACH messages using an alternative set of subframes, different from conventionally-defined subframe set; (4) configuring LBL devices to transmit PRACH messages on odd frames when the conventional PRACH configuration specifies even frames; (5) configuring LBL devices to generate and use extra PRACH preambles that are not used by non-LBL devices; (6) configuring LBL devices to use group B preambles while non-LBL devices are configured to use group A preambles; and (7) boosting power of a random access response message after an Nth random access failure with preamble conforming to an LBL-reserved pattern of preambles.

主权项

1. A method for operating a user equipment device, the method comprising:
receiving a logical root sequence number that has been broadcast by a base station; generating a set of preambles based on data including the logical root sequence number, wherein said generating includes determining a first physical root sequence number according to a conventional mapping of logical root sequence numbers to physical root sequence numbers, wherein the set of preambles includes: a first subset of preambles for transmission of a Physical Random Access Channel (PRACH) by non-link-budget-limited UE devices; and a second subset of preambles for transmission of the PRACH by link-budget-limited UE devices, wherein the first subset and the second subset are disjoint sub sets; in response to a determination that the UE device has been classified as being link budget limited, transmitting the PRACH to the base station using one of the preambles from the second subset.