PRACH Resource Segmentation for MTC Uplink Collision Reduction
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Solution Overview
Problem
The increasing number of Machine-Type Communication (MTC) users and terminals in cellular networks leads to resource allocation inefficiencies and challenges in ensuring coverage performance, particularly due to high pathloss from MTC terminals mounted indoors, which complicates uplink and downlink signal reception.
Innovation Solution
A random access method where User Equipment (UE) selects a physical random access channel (PRACH) resource from pre-configured resources to transmit preambles, allowing the eNB to respond correctly, and the eNB configures multiple PRACH resources for UEs to reduce collision probability and improve allocation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple PRACH resources are configured for random access, then allocation efficiency is improved, but collision probability increases
Solution Approach 1:
The PRACH resources are segmented into multiple separate resources (different time slots, frequency resources, or codes) that are independently configured. UEs can select from these segmented resources, which allows better distribution of access attempts and reduces collisions while maintaining high allocation efficiency through the multiple available options.
Solution Approach 2:
The system dynamically configures multiple PRACH resources based on network conditions and UE requirements. The eNB can adaptively adjust the number, position, and characteristics of PRACH resources to optimize both allocation efficiency and collision avoidance under different traffic loads and channel conditions.
2Device complexity
If MTC terminals are mounted indoors with high separation, then device complexity is reduced, but pathloss increases
Solution Approach 1:
The patent introduces frequency domain hopping as an additional dimension for PRACH resource utilization. By hopping across different frequency resources for repeated preamble transmissions, the system exploits frequency diversity to overcome the high pathloss caused by indoor mounting, allowing low-complexity terminals to achieve reliable uplink access without increasing device complexity.
Solution Approach 2:
The system employs periodic repeated transmissions of preambles with frequency hopping at regular intervals. This periodic action allows the signal to experience different channel conditions over time and frequency, increasing the probability of successful reception despite high initial pathloss, while keeping the terminal structure simple.
3Reliability
If preambles are transmitted multiple times with frequency hopping, then coverage performance is improved, but use of energy increases
Solution Approach 1:
The system implements a balanced approach where preambles are transmitted multiple times with frequency hopping, but the number of repetitions is optimized to be sufficient for coverage enhancement without excessive energy consumption. The eNB can configure the appropriate number of repetitions based on UE capability and channel conditions, achieving partial action that balances coverage and energy efficiency.
Data Source
AI summary
Embodiments of the present invention provide a random access method and apparatus and system. Where, the method includes: selecting randomly, by UE, a physical random access channel (PRACH) resource for transmitting a preamble from multiple PRACH resources pre-configured by an eNB for the UE; and transmitting the preamble by the UE on a selected PRACH resource, so that the eNB transmits a random access response to UE to which a correctly demodulated preamble corresponds according to preambles transmitted by UEs. With the method and apparatus of the embodiments of the present invention, coverage performance of an uplink channel and a downlink channel may be improved.