Uplink Carrier RAR Distinction via MAC PDU Indication
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Solution Overview
Problem
In 5G communication systems, the limited uplink coverage due to high-frequency NR spectrum and the introduction of a secondary LTE uplink carrier leads to conflicts in distinguishing the downlink Random Access Response (RAR) corresponding to a preamble on either the first or second uplink carrier, as PRACH resources are configured independently, causing potential multiplexing of RARs.
Innovation Solution
A method for contention-based random access that configures distinct Random Access Preamble Identifiers (RAPID) and Radio Network Temporary Identifiers (RA-RNTI) for each uplink carrier, ensuring non-intersecting index numbers and inclusion of indication information in MAC PDUs to differentiate RARs, preventing conflicts and allowing the terminal device to accurately identify the uplink carrier for each RAR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a secondary LTE uplink carrier is introduced to improve uplink coverage, then uplink coverage is improved, but conflicts occur in distinguishing the downlink Random Access Response corresponding to a preamble on either the first or second uplink carrier
Solution Approach 1:
The patent segments the RAR identification mechanism by introducing a new field in the MAC PDU that explicitly indicates which uplink carrier (first or second) the RAR corresponds to. This segmentation allows the terminal device to clearly distinguish between RARs for different uplink carriers, resolving the ambiguity that arises from having two independent PRACH resources on different carriers.
2Adaptability or versatility
If independent PRACH resources are configured on two carriers, then each carrier can operate independently, but the preamble indexes and RA-RNTIs may conflict, causing the terminal device to be unable to distinguish the UL carrier
Solution Approach 1:
The patent introduces an intermediary indicator field within the MAC PDU structure that acts as a mediator between the two independent PRACH resources. This indicator explicitly identifies which uplink carrier the RAR corresponds to, allowing independent carrier operation to be maintained while eliminating the ambiguity in carrier identification that would otherwise result from independent preamble and RA-RNTI configurations.
Data Source
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AI summary
Provided are a method for contention-based random access, a network device and a terminal device. The method comprises: a network device receiving, on a first uplink carrier or a second uplink carrier, a first preamble sent by a terminal device, a frequency point of the first uplink carrier being different from a frequency point of the second uplink carrier; and the network device sending to the terminal device a media access control (MAC) protocol data unit (PDU) , wherein the MAC PDU comprises a first media access control (MAC) random access response (RAR) corresponding to the first preamble. The method in the embodiments of the present invention can enable a terminal device to effectively distinguish that a received first MAC RAR is the RAR of a preamble sent on which uplink carrier.