Random Access Procedure Congestion Control in eMTC Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, especially LTE networks, congestion occurs during random access procedures of eMTC UEs due to high numbers of devices initiating access simultaneously, leading to increased power consumption and limited M-PDCCH capacity for contention resolution messages.
Innovation Solution
The proposed solution involves a time-frequency resource index included in the random access response (RAR) message, which allows eMTC UEs to defer initiating the contention resolution timer and monitoring the M-PDCCH, reducing unnecessary power consumption by specifying a delay time and potentially different frequency resources for monitoring the contention resolution message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If eMTC UEs monitor M-PDCCH continuously for contention resolution messages, then contention resolution reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic monitoring of M-PDCCH by eMTC UEs for contention resolution messages, where UEs monitor at specific intervals rather than continuously. The network schedules contention resolution messages in periodic time-frequency resources, allowing UEs to wake up periodically to check for messages and enter low-power mode between monitoring instances, thus reducing overall power consumption while maintaining reliable contention resolution delivery.
2Productivity
If multiple eMTC UEs initiate random access simultaneously, then network access capability is improved, but congestion occurs
Solution Approach 1:
The patent introduces time and frequency dimensions for resource allocation of contention resolution messages. Instead of all UEs competing for the same resources, the network assigns different time slots and frequency resources to different UEs or UE groups for receiving contention resolution messages. This dimensional separation disperses the congestion across multiple resources, allowing simultaneous random access initiations to be handled efficiently without overwhelming any single resource.
Solution Approach 2:
The patent segments the contention resolution process by assigning different time-frequency resource sets to different UEs or UE groups. The RAR message includes indicators that guide UEs to specific segmented resources for monitoring contention resolution messages. This segmentation divides the congested access scenario into multiple manageable streams, reducing collision and interference while maintaining high network access capability.
3Productivity
If M-PDCCH capacity is increased to handle more contention resolution messages, then random access throughput is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary scheduling where the network pre-allocates time-frequency resources for contention resolution messages before UEs need to monitor them. The RAR message contains pre-configured resource indicators that tell UEs exactly when and where to monitor for their contention resolution messages. This preliminary action allows the network to manage M-PDCCH capacity efficiently by spreading messages across pre-planned resources, increasing throughput without requiring complex dynamic resource allocation in real-time at the UE side.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Apparatuses, methods, and systems are disclosed for alleviating congestion during random access of enhanced machine-type communications user equipment. One apparatus includes a radio transceiver that communicates over a mobile telecommunications network and a processor configured to: transmit a physical random access channel (PRACH) preamble on a first time-frequency resource, monitor a second time-frequency resource for a first downlink (DL) grant scheduling a random access response (RAR) corresponding to the transmitted PRACH preamble on a third time-frequency resource, receive the RAR on the third time-frequency resource, transmit a message on a fourth time-frequency resource, wherein the fourth time-frequency resource is determined based on the RAR; determine a fifth time-frequency resource based on a time-frequency resource index, wherein the RAR includes the time-frequency resource index, and monitor the fifth time-frequency resource for a second DL grant scheduling a contention resolution message.