Staggered RACH Slot Allocation for Low-Latency Uplink Access
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Solution Overview
Problem
5G mmWave networks face challenges in maintaining low-latency uplink access due to radio link blockages caused by obstacles, which result in increased latency and system control overhead when reducing RACH periodicity to meet target latency requirements.
Innovation Solution
The method involves allocating random-access-channel (RACH) slots across multiple access points in a cluster set such that they are staggered in time, allowing the user device to use the earliest available RACH slot for uplink access, thereby reducing latency while minimizing system control overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If RACH periodicity is reduced to meet target latency requirements, then uplink access latency is improved, but system control overhead increases
Solution Approach 1:
The patent divides the network into multiple access points forming a cluster set, where each access point is responsible for serving a subset of user devices. The RACH slots are segmented and allocated to different access points in a staggered manner, distributing the control overhead across multiple nodes rather than concentrating it at a single point, thus reducing the overall system control overhead while maintaining low latency.
Solution Approach 2:
The patent introduces a new dimension of spatial distribution by allocating RACH slots across multiple access points in different time positions within the frame structure. Instead of increasing RACH periodicity frequency uniformly, the solution distributes RACH opportunities across the temporal and spatial dimensions, allowing user devices to access the earliest available slot while balancing the control overhead distribution.
2Reliability
If RACH slots are allocated to multiple access points, then uplink access reliability is improved, but frame structure complexity increases
Solution Approach 1:
The patent implements a periodic allocation pattern where RACH slots are distributed in a regular, repeating sequence across the cluster set of access points. Each access point is assigned RACH slots at specific periodic intervals within the frame structure, creating a predictable and manageable pattern that reduces complexity while ensuring reliable access opportunities for user devices.
Solution Approach 2:
The patent modifies the frame structure parameters by introducing staggered time offsets for RACH slots across different access points. Instead of using a uniform frame structure, the solution adjusts the temporal parameters of RACH slot allocation to create a staggered pattern that simplifies the overall system operation while maintaining reliability through diversified access paths.
3Productivity
If RACH slots are staggered in time across access points, then uplink access efficiency is improved, but timing synchronization difficulty increases
Solution Approach 1:
The patent implements feedback mechanisms where user devices monitor and detect the timing of RACH slots from multiple access points, and the network uses this information to adjust and optimize the staggered slot allocation. The feedback loop enables continuous refinement of timing synchronization, maintaining accurate alignment despite the staggered distribution across multiple access points.
Solution Approach 2:
The patent performs preliminary timing synchronization and configuration of RACH slot offsets before actual uplink access operations begin. The network pre-calculates and configures the staggered time positions for each access point based on predicted traffic patterns and geometric relationships, establishing a synchronized framework in advance that simplifies real-time operations while maintaining high efficiency.
Data Source
AI summary
A method and apparatus may determine a plurality of access points. The plurality of access points belong to a cluster set of a user device. The method may also include allocating a plurality of random-access-channel slots to the plurality of access points such that the plurality of random-access-channel slots are staggered in time over a random-access-channel period within a frame structure used by the user device.