Beam-Based PRACH Access Using Reference Signal Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in 6G wireless communication systems is the high transmission delay and resource wastage due to the use of numerous beams in terahertz frequency bands, leading to inefficient random access preamble transmission in existing technologies.
Innovation Solution
A method and apparatus for performing random access by selecting and designing a new preamble transmission structure and reducing preamble transmission delays and improving preamble efficiency by selecting and transmitting a random access preamble through a physical random access channel (PRACH) resource corresponding to a reference signal selected by measuring the at least one reference signal, and transmitting a preamble through a physical random access channel (PRACH) resource corresponding to the selected reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clear channel assessment is performed before random access transmission, then the success rate of random access is improved, but the access delay increases due to additional signaling overhead
Solution Approach 1:
The patent extracts the clear channel assessment function from the traditional random access procedure and integrates it into the physical random access channel transmission itself. The UE transmits both the random access preamble and channel assessment information simultaneously in the same uplink slot, removing the separate assessment step that caused delay.
Solution Approach 2:
The patent merges the random access preamble transmission with the clear channel assessment transmission into a single unified signal. The physical random access channel transmission contains both the preamble sequence for random access and the channel state information for clear channel assessment, eliminating the need for separate signaling operations.
2Speed
If multiple UEs transmit random access signals simultaneously, then the access speed is improved, but collision between signals occurs reducing success rate
Solution Approach 1:
The patent applies local quality by assigning different cyclic shifts of the Zadoff-Chu sequence to different UEs within the same resource. Each UE uses a locally distinct cyclic shift value, creating orthogonal or near-orthogonal signals that can be distinguished at the receiver even when transmitted simultaneously on the same physical resources.
Solution Approach 2:
The patent changes the parameter of the random access preamble by applying different cyclic shifts to the base Zadoff-Chu sequence. Instead of using the same sequence for all UEs, the system varies the cyclic shift parameter to create unique signatures for each UE, enabling simultaneous transmissions to be differentiated.
3Quantity of substance
If the random access resource is increased to accommodate more UEs, then the access capacity is improved, but the system complexity increases
Solution Approach 1:
The patent makes the physical random access channel multi-functional by enabling it to serve both random access purposes and clear channel assessment purposes simultaneously. The same uplink resources are used for both functions, eliminating the need for separate dedicated assessment resources and increasing overall system capacity without proportional increases in complexity.
Solution Approach 2:
The patent adds the cyclic shift dimension to the random access signal space. By utilizing cyclic shifts as an additional degree of freedom, the system can accommodate more UEs using the same time-frequency resources, effectively increasing capacity through dimensional expansion rather than resource proliferation.
Data Source
Figure 1~2
Figure 3~4b
Figure 4c~6
AI summary
The disclosure relates to a 5th generation (5G) or 6th generation (6G) communication system for supporting a higher data transmission rate than a post-4th Generation (4G) communication system such as long-term evolution (LTE). A method of performing random access by a user equipment (UE) in a wireless communication system is provided. The method includes receiving a first signal including at least one reference signal from a base station (BS), measuring the at least one reference signal and transmitting a second signal to the BS through first uplink resources corresponding to a selected reference signal, and transmitting a random access preamble through a physical random access channel (PRACH) resource corresponding to the selected reference signal.