Random Access Response Message for MTC UE Coverage Enhancement
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Solution Overview
Problem
Machine Type Communication (MTC) User Equipment (UE) in LTE/LTE-A systems faces challenges in cost reduction while maintaining performance, especially in scenarios with penetration loss, requiring enhanced uplink/downlink coverage and efficient access mechanisms, particularly in the design of the Physical Random Access Channel (PRACH) and Random Access Response (RAR) to ensure reliable system access.
Innovation Solution
A method for sending an enhanced RAR message through a downlink channel, which includes scheduling information for multiple levels of MTC UEs, using resource allocation information, Backoff Indicator (BI) index, and Uplink Delay information to optimize resource allocation and access timing, ensuring proper access and coverage enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cost reduction measures are applied to MTC UE (reducing receiving antennae, baseband processing bandwidth, peak rate), then device cost is reduced, but coverage performance deteriorates
Solution Approach 1:
The patent implements dynamic coverage enhancement by enabling MTC UEs to adaptively select from multiple CE levels (CE0, CE1, CE2) based on their received signal quality. The system dynamically adjusts uplink transmission parameters including power boosting factors, repetition numbers, and resource allocation according to the selected CE level, allowing cost-reduced UEs to achieve reliable coverage through adaptive parameter adjustment rather than hardware enhancements.
Solution Approach 2:
The patent changes multiple transmission parameters to compensate for hardware limitations: uplink power boosting (increasing transmit power by specific dB values), repetition counting (transmitting multiple copies of data), resource block allocation adjustments, and modulation scheme selection. These parameter changes enable cost-reduced UEs to achieve reliable communication despite having fewer receiving antennae and lower baseband processing capabilities.
2Reliability
If enhanced PRACH design is implemented for MTC UE, then access quality is improved, but system complexity increases
Solution Approach 1:
The patent segments the random access process into distinct phases with different CE level requirements. MTC UEs first perform preamble transmission on PRACH using coverage enhancement parameters, then receive RAR messages that indicate whether to proceed with normal or enhanced uplink transmission. This segmentation allows the system to apply enhanced design only where necessary (for UEs in poor coverage) while maintaining standard operation for others, thus improving access quality without uniformly increasing system complexity.
Solution Approach 2:
The patent introduces the RAR message as an intermediary that carries coverage enhancement indication information. This intermediary enables the network to dynamically guide MTC UEs on whether to apply enhanced uplink transmission parameters based on their actual coverage conditions. The RAR acts as a mediator between the simplified UE design and the enhanced network requirements, allowing cost-reduced UEs to achieve reliable access through network-guided parameter adjustment rather than complex built-in decision-making capabilities.
3Adaptability or versatility
If RAR is enhanced to carry resource allocation for multiple CE levels, then MTC UE access is improved, but message complexity increases
Solution Approach 1:
The patent enhances the RAR message to serve multiple functions simultaneously: it provides random access response, indicates coverage enhancement level requirements, allocates uplink resources, and guides subsequent transmission parameters. By making the RAR message multi-functional, the system avoids creating separate specialized messages for each function, thereby improving MTC UE access support while controlling message complexity through consolidation rather than proliferation of message types.
Solution Approach 2:
The patent nests coverage enhancement indication information and resource allocation parameters within the existing RAR message structure. Rather than creating separate external messages, the enhancement parameters are embedded (nested) within the RAR framework. This nesting approach allows the RAR to carry both traditional response information and new coverage enhancement directives in a unified structure, improving adaptability while avoiding the complexity overhead of multiple separate message exchanges.
Data Source
AI summary
The document discloses a method for sending a Random Access Response (RAR) message and a node. The method includes: a first type node sends an RAR through a downlink channel, and the RAR carries one or more pieces of RAR information of a second type node.