Dynamic Root Sequence Allocation for LTE Access Nodes
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Solution Overview
Problem
The existing method of configuring root sequences for access nodes based on a fixed coverage radius limits the number of available root sequences, leading to degraded network performance, including delayed call setup requests and handover success rates due to insufficient RACH preambles.
Innovation Solution
Determine the coverage radius and neighbor lists for each access node, calculate the required number of root sequences based on the coverage radius, and assign them using a cyclic shift of the root sequence, ensuring unique sequences for each access node to mitigate confusion and optimize preamble availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If root sequences are assigned based on fixed coverage radius, then access node configuration is simplified, but the number of available root sequences is limited leading to degraded network performance
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed coverage radius model to a dynamic model that determines coverage radius based on actual transmission power and measured path loss. This allows the system to adapt to varying network conditions and allocate root sequences more effectively, resolving the contradiction between configuration simplicity and network performance reliability.
Solution Approach 2:
The patent changes the parameter used for root sequence assignment from a fixed coverage radius to a dynamically calculated coverage radius based on transmission power and path loss measurements. This parameter change enables more accurate root sequence allocation that adapts to actual network conditions, improving both performance and configuration flexibility.
2Area of stationary object
If larger coverage area is used, then access node serves more users, but larger cyclic shift is required reducing preamble availability
Solution Approach 1:
The patent changes the cyclic shift parameter dynamically based on the calculated coverage radius. By determining the coverage radius from actual transmission power and path loss measurements, the system can optimize the cyclic shift value to match the actual coverage area, ensuring sufficient preamble availability while maximizing coverage.
Solution Approach 2:
The system dynamically adjusts the cyclic shift parameter according to the actual coverage radius determined by transmission power and path loss conditions. This dynamic adaptation allows the system to maintain optimal preamble availability across varying coverage areas, resolving the trade-off between coverage size and preamble resources.
3Reliability
If unique root sequences are assigned to all access nodes, then confusion among initial access requests is mitigated, but root sequence assignment becomes more complex
Solution Approach 1:
The patent applies local quality by assigning root sequences based on the specific coverage characteristics and transmission power levels of each access node rather than using a uniform assignment scheme. This localized approach ensures unique root sequences are assigned where needed to prevent confusion, while simplifying the assignment process for nodes with similar characteristics.
Solution Approach 2:
The system uses dynamically calculated coverage radius parameters to determine root sequence assignments. By basing the assignment decision on the actual coverage characteristics derived from transmission power and path loss measurements, the system achieves reliable request distinction while maintaining a systematic and manageable assignment process.
Data Source
AI summary
In systems and methods of allocating root sequences to access nodes, a first coverage radius and a first neighbor list of a first access node are determined, wherein the first neighbor list comprises second access nodes which are each a neighbor access node of the first access node. A second coverage radius and a second neighbor list of each of the second access nodes is then determined. An access node comprising a largest coverage radius from among the first access node and the second access nodes is selected. A number of root sequences required for the selected access node is calculated based on the coverage radius of the selected access node, and root sequences are assigned to the selected access node according to the number of root sequences required.