RACH Preamble Collision Detection via Sequence Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly in 3GPP LTE, detecting random access channel (RACH) preamble collisions caused by multi-path channel delays is challenging, leading to difficulties in maintaining UL synchronization and potentially causing service delays, especially for UEs requiring urgent access.
Innovation Solution
A method and device that utilize a multi-quality of service (QoS) concept to differentiate and prioritize RACH preambles by using a combination of sequences with varying cyclic shift offsets, enabling the eNB to detect collisions more accurately and rapidly, even in environments with multi-path channel delays, by comparing received patterns and power ratios of RACH preambles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-coherent detection is used for RACH preamble transmission, then the eNB can recognize simultaneous preambles from multiple UEs as collision, but when time delay occurs due to multi-path channel, the eNB cannot immediately determine whether preambles collide
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple candidate RACH preambles with distinct auto-correlation patterns before transmission. When a preamble is transmitted, the eNB can immediately compare the received signal against these pre-defined patterns to detect collisions without waiting for time delay resolution, thus resolving the contradiction between detection accuracy and time loss.
Solution Approach 2:
The patent changes the parameter of preamble structure by using preambles with specific auto-correlation properties (zero auto-correlation at certain lags). This parameter change enables the eNB to distinguish between actual collisions and multi-path delays by examining the correlation pattern at different time lags, thereby achieving accurate collision detection despite time delays.
2Adaptability or versatility
If traditional RACH preamble structure is used, then the system maintains simplicity, but it cannot provide precedence connection support for specific UEs in multi-path channel environments
Solution Approach 1:
The patent applies segmentation by dividing the RACH preamble into multiple segments or candidate preambles, each with distinct auto-correlation characteristics. This segmentation allows the system to support different connection priorities (e.g., emergency vs. normal services) while maintaining a structured approach that doesn't excessively increase complexity. The eNB can select appropriate segments based on service requirements.
Solution Approach 2:
The patent applies local quality by assigning different auto-correlation properties to different preamble candidates based on their intended use (e.g., different services or priority levels). This allows specific UEs requiring precedence connection support to use preambles with properties optimized for their needs, while other UEs use standard preambles, thus adding adaptability without uniformly increasing system complexity.
3Reliability
If the eNB waits for time delay resolution before determining collision, then false collision detection is reduced, but service delays occur especially for UEs requiring urgent access
Solution Approach 1:
The patent applies feedback by implementing a mechanism where the eNB immediately provides feedback to UEs about detected collisions based on pre-defined preamble patterns. This feedback loop allows UEs to quickly retransmit or select alternative preambles without waiting for time delay resolution, maintaining both detection reliability and access speed. The feedback includes collision detection results and guidance for resolution.
Solution Approach 2:
The patent applies preliminary action by pre-configuring multiple candidate preambles with known auto-correlation properties before the random access procedure. This allows the eNB to immediately determine collisions by comparing received signals against pre-defined patterns without waiting for time delay effects to resolve, thus improving both reliability and productivity simultaneously.
Data Source
AI summary
Provided is a method for detecting whether a random access channel (RACH) preamble collision occurs in a wireless communication system. An evolved Node B (eNB) receives, from a first user equipment (UE), a first RACH preamble generated by using a combination of a plurality of sequences, and also receives, from a second UE, a second RACH preamble generated by using one sequence. The eNB detects whether a collision occurs between the first RACH preamble and the second RACH preamble on the basis of the received patterns of the first RACH preamble and the second RACH preamble, wherein the received patterns of the first RACH preamble and the second RACH preamble are based on channel delay caused by multiple paths.