Adaptive Guard Band for Low Latency Random Access
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving low latency and high reliability, particularly in scenarios like vehicular networking and industrial autonomous control, due to high latency and collision risks during random access procedures in LTE networks.
Innovation Solution
The solution involves a user equipment device that transmits a random access request and data message with different time units, uses unique or compressed signatures for identification, and employs an adaptive frequency guard band based on time misalignment to reduce latency and prevent collisions, allowing for non-synchronous data frame transmission and efficient resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the time unit of random access request is made shorter to reduce latency, then the latency is reduced, but the frame duration becomes non-isometric causing time misalignment between adjacent frequency sub-bands
Solution Approach 1:
The patent applies asymmetry by allowing different time units for random access requests compared to data messages. Specifically, random access requests can have a shorter time unit duration than data messages, creating a non-isometric frame structure. This asymmetric design enables reduced latency for random access procedures while accepting that frame durations will differ across message types, thereby resolving the contradiction between latency reduction and frame alignment stability.
Solution Approach 2:
The patent implements dynamics by making the frame structure adaptable rather than fixed. The system allows random access requests to have flexible, shorter time units independent of the fixed data message frame duration. This dynamic approach enables the random access procedure to optimize its timing for low latency requirements without being constrained by the standard data message frame structure, thus reducing latency while managing the resulting time misalignment through other mechanisms.
2Reliability
If unique signatures are used for each user equipment device to prevent collisions, then collision probability is reduced, but the bandwidth required for signature transmission increases
Solution Approach 1:
The patent applies partial action by using compressed signatures that provide sufficient uniqueness for collision avoidance without requiring full-length unique identifiers for each device. The compressed signature scheme uses a reduced representation (e.g., hash or truncated sequence) that maintains collision probability below acceptable thresholds while consuming significantly less bandwidth than complete unique device identifiers, thus balancing reliability and bandwidth consumption.
Solution Approach 2:
The patent implements parameter changes by transforming the signature representation from full-length unique identifiers to compressed forms. This parameter transformation maintains the essential distinguishing property needed for collision-free access while reducing the bandwidth parameter. The system changes the signature from a high-bandwidth full identifier to a lower-bandwidth compressed version that still provides sufficient uniqueness for the random access procedure.
Data Source
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AI summary
The present invention relates to a random access scheme exhibiting a non-isometric frame duration and a low latency. The RA and data messages have a duration with a different time unit and the time slot of the RA message is much shorter than the duration of one data frame. A specific signature, which is designed to be robust against the collisions, is transmitted during the RA request, the signature being either a unique sequence or a compressed signature. The user equipment device transmits the data message immediately after receiving its resource through a frame structure showing a time misalignment between adjacent data frames located in different or identical frequency sub-bands. A frequency guard band is inserted between its resource and an adjacent resource assigned to another user equipment device, the frequency guard band having an adaptive size according to the level of time misalignment and its impact on the distortion.