LTE Random Access Carrier Selection for Handover Resource Optimization
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Solution Overview
Problem
In the current LTE system, during handover, the target eNB cannot determine which component carrier the UE is monitoring, leading to a waste of downlink resources as it sends random access response messages on all component carriers.
Innovation Solution
The UE learns the target component carriers from the handover command and receives the random access response message on the designated downlink target component carrier, while the target eNB determines the component carriers for sending the random access response message after receiving the dedicated random access preamble from the UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target eNB sends the random access response message on all component carriers, then the UE can reliably receive the message, but downlink resources are wasted
Solution Approach 1:
The patent segments the downlink component carriers and identifies specific carriers for random access response message transmission. Instead of broadcasting on all carriers, the system divides the carriers and assigns specific ones for random access responses based on uplink carrier mappings, reducing unnecessary transmissions while ensuring reliable delivery on the designated carriers.
2Reliability
If the UE monitors all component carriers for random access response, then the message can be received reliably, but power consumption increases
Solution Approach 1:
The patent segments the component carriers and informs the UE which specific downlink carriers to monitor for random access response messages. The UE only needs to monitor the designated downlink carrier(s) corresponding to the uplink carrier used for random access preamble transmission, rather than monitoring all carriers, thus reducing power consumption while maintaining reliable reception.
3Reliability
If the target eNB sends random access response on all component carriers, then message delivery is ensured, but system complexity increases
Solution Approach 1:
The patent segments the component carriers and establishes specific mapping relationships between uplink and downlink carriers for random access procedures. The target eNB only needs to transmit random access response messages on the identified downlink carriers rather than all carriers, simplifying the transmission process and reducing processing complexity while ensuring reliable message delivery.
4Reliability
If dedicated random access preamble is allocated, then non-competitive random access is enabled, but the eNB cannot determine the monitoring carrier without additional information
Solution Approach 1:
The patent applies preliminary action by pre-establishing the mapping relationship between uplink component carriers and downlink component carriers before the random access procedure. When the UE transmits the random access preamble on a specific uplink carrier, the target eNB can immediately determine the corresponding downlink carrier for sending the random access response message, eliminating the need for additional carrier identification information exchange.
Data Source
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Figure 3B
AI summary
A random access method, an evolved Node B (eNB), and a terminal equipment are provided. The method includes: determining target component carriers to which a User Equipment (UE) is to be handed over, and notifying the UE of information about the target component carriers through a source eNB; and after receiving a dedicated random access preamble sent by the UE, sending a random access response message on at least one component carrier in the target component carriers. The terminal equipment includes: a handover command receiving unit, a sending unit, and a random response receiving unit. Therefore, in a random access procedure of cell handover, the eNB is capable of determining downlink component carriers that a UE monitors, thereby increasing utilization rate of downlink resources.