Multi-QCL PDCCH Orders for Reliable Wireless Random Access
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Solution Overview
Problem
The existing wireless communication systems face challenges in efficiently handling the increased demand for data traffic, transmission rate, and the need for low latency and high energy efficiency, particularly in scenarios where PDCCH orders are blocked or ambiguous, affecting the reliability of random access procedures.
Innovation Solution
A method and apparatus are developed to perform random access procedures by transmitting and receiving channel state information using a plurality of quasi co-location (QCL) reference signals, allowing for reliable PDCCH order transmission and reception, even in blocked conditions, and clarifying ambiguity through multiple synchronization signal block indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single PDCCH order is used to trigger random access procedure, then the procedure is simple and fast, but reliability deteriorates when the PDCCH order is blocked or ambiguous
Solution Approach 1:
The patent divides the PDCCH order transmission into multiple segments by using multiple search spaces (SS sets) with different QCL RSs. Instead of transmitting a single PDCCH order, the system transmits multiple PDCCH orders, each associated with a different QCL RS (e.g., SSB 0, SSB 1, SSB 2), allowing the terminal to select the appropriate one based on detection results. This segmentation approach improves reliability without excessive complexity.
Solution Approach 2:
The patent introduces a new dimension of transmission by mapping multiple PDCCH orders to different QCL RSs and search spaces. The terminal evaluates detection results across multiple dimensions (different SS sets, different QCL RSs) and selects the appropriate PRACH occasion accordingly. This dimensional expansion enables the system to handle blocking and ambiguity issues that would otherwise cripple single-dimension approaches.
2Reliability
If multiple QCL RSs are used for PDCCH order transmission, then reliability improves under blocked conditions, but ambiguity may arise in selecting the correct PRACH occasion
Solution Approach 1:
The patent implements a feedback mechanism where the terminal reports detection results for each PDCCH order associated with different QCL RSs. Based on this feedback, the terminal determines which PRACH occasion to use. The base station receives this feedback and adjusts the random access procedure accordingly, eliminating ambiguity through structured information exchange.
Solution Approach 2:
The patent applies local quality by associating specific PRACH occasions with specific QCL RSs and search spaces. Each PDCCH order is locally optimized for a particular QCL RS, and the terminal selects the appropriate local configuration based on detection results. This localized approach prevents ambiguity by ensuring that each transmission path has a dedicated, well-defined purpose.
3Reliability
If the terminal monitors multiple search spaces for PDCCH order, then the system can handle blocked PDCCH, but the monitoring complexity and time increase
Solution Approach 1:
The patent performs preliminary action by pre-configuring multiple search spaces with different QCL RSs before the actual PDCCH transmission. The terminal is provided with configuration information about multiple SS sets and their associated QCL RSs in advance, so when PDCCH monitoring begins, the terminal can immediately evaluate multiple options without time-consuming setup. This preliminary preparation significantly reduces monitoring time despite the increased number of search spaces.
Data Source
AI summary
A method and a device for performing a random access procedure in a wireless communication system are disclosed. A method for performing a random access procedure according to an embodiment of the present disclosure may comprise the steps of: receiving, from a base station, a first PDCCH including a PDCCH order for triggering a random access procedure, wherein the first PDCCH is transmitted on multiple SS sets, the multiple SS sets are associated with multiple CORESETs, respectively, and multiple different quasi co-location (QCL) RSs are configured in multiple TCI states for the multiple CORESETs; transmitting a PRACH for the random access procedure to the base station in response to the PDCCH order; and receiving, from the base station, a second PDCCH including DCI for scheduling a PDSCH carrying a random access response for the random access procedure in response to the PRACH.