Random Access Simplification in Ultra-Dense Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In ultra-dense networks (UDN), the random access (RA) process in LTE systems faces challenges due to reduced timing differences and shorter channel delays, leading to unnecessary uplink synchronization, which can cause inter-carrier and intersymbol interference, and complicates the RA process.
Innovation Solution
The method involves a base station in a target cell sending an uplink grant message directly to user equipment (UE), allowing the UE to transmit information without the need for uplink synchronization using a timing advance mechanism, thereby simplifying the RA process and improving system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If uplink synchronization is performed using timing advance mechanism in UDN, then UL timing alignment is achieved, but RA process complexity increases and system efficiency decreases
Solution Approach 1:
The patent extracts and removes the timing advance mechanism from the RA process in UDN scenarios. Since UDN's small cell radius naturally provides sufficient CP coverage for UL timing alignment, the TA mechanism is taken out as unnecessary, simplifying the RA process while maintaining UL synchronization stability
Solution Approach 2:
The patent changes the system parameter from macro cell radius to ultra-small cell radius in UDN. This parameter change fundamentally alters the propagation delay characteristics, making the TA mechanism unnecessary and enabling direct UL transmission without timing advance adjustment
2Stability of the object's composition
If timing advance mechanism is used for UL synchronization, then UL timing difference is compensated, but transmission delay increases
Solution Approach 1:
The patent removes the timing advance adjustment step from the RA process. By extracting this unnecessary synchronization step in UDN, the transmission delay is reduced while UL synchronization is maintained through the naturally short propagation delay characteristic of small cells
3Stability of the object's composition
If RA process includes timing advance command, then UL timing alignment is achieved, but signaling overhead increases
Solution Approach 1:
The patent extracts and eliminates the timing advance command signaling from the RA message structure. In UDN, since the small cell radius ensures sufficient CP coverage, this signaling element is removed entirely, reducing downlink signaling overhead while maintaining UL timing alignment
Solution Approach 2:
The patent discards the TA command in RAR message for UDN scenarios. The system recovers by relying on the inherent timing characteristics of small cells, where the propagation delay is naturally within the CP protection interval, making explicit TA signaling redundant
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Embodiments of the present invention provide an access method, a device, and a system, to simplify an RA process and improve system efficiency. The method includes: sending, by a base station in a target cell, first information to UE, where the first information is an uplink grant UL grant message, so that the UE sends information on an uplink UL based on the first information. The embodiments of the present invention are used for access.