MPDCCH Resource Allocation for Narrowband MTC Coverage
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Solution Overview
Problem
The existing LTE system is inadequate for supporting narrowband Machine Type Communication (MTC) user equipment, as it cannot efficiently transmit and receive downlink control channels due to limitations in physical resource block pair allocations, which result in poor signal strength and coverage in MTC devices operating at 1.4 MHz bandwidth, especially in environments with penetration losses such as thick walls or metal structures.
Innovation Solution
A method for allocating physical resource block pairs and repetition levels for the evolved physical downlink control channel (MPDCCH) in the LTE system, allowing for transmission and reception of downlink control information to narrowband MTC user equipment, enabling enhanced coverage and support for MTC devices by allocating specific PRB-sets and aggregation levels, and transmitting the MPDCCH within one or multiple subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If broadband PDCCH is used for downlink control channel transmission, then control information coverage is improved, but narrowband MTC user equipment cannot receive it due to bandwidth limitations
Solution Approach 1:
The patent segments the control channel transmission by introducing a narrowband PDCCH (NPDCCH) specifically for MTC UEs with 1.4 MHz bandwidth. This segmentation allows the system to provide both broadband PDCCH for conventional UEs and narrowband NPDCCH for MTC UEs, resolving the contradiction between coverage area and adaptability to narrowband devices.
Solution Approach 2:
The patent introduces an intermediary mechanism by defining a separate NPDCCH channel that acts as a mediator between the control plane and narrowband MTC UEs. This intermediary NPDCCH enables MTC UEs to receive control information without requiring them to support broadband PDCCH, thus resolving the incompatibility issue.
2Reliability
If repeat transmission is used to enhance coverage for MTC UEs, then received signal strength is improved, but transmission time and complexity increase
Solution Approach 1:
The patent implements dynamic repeat transmission where the base station adaptively determines the number of repetitions based on channel conditions and MTC UE requirements. The repetition count can be dynamically adjusted between 1-32 times, allowing the system to optimize between reliability and time loss by using more repetitions only when necessary for poor channel conditions.
Solution Approach 2:
The patent changes the transmission parameter by introducing a repetition factor that multiplies the number of times control information is transmitted. This parameter change allows the system to enhance received signal strength through multiple transmissions while controlling time loss by optimizing the repetition count based on channel quality indicators.
3Reliability
If subframe bundling is used to improve MTC physical channel signal strength, then coverage enhancement is achieved, but system complexity and resource allocation difficulty increase
Solution Approach 1:
The patent segments the resource allocation by dedicating specific physical resource block pairs (PRB pairs) exclusively for NPDCCH transmission to MTC UES. This segmentation simplifies resource allocation complexity by creating dedicated resources for MTC control channels, avoiding the need for complex shared resource management while still achieving coverage enhancement through proper resource selection and bundling.
Data Source
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AI summary
The embodiments of the present invention provide a transmission and reception mechanism for a downlink control channel applicable to a narrowband MTC UE, and a base station and a user equipment for executing the mechanism. The method according to the embodiment of the present invention includes: determining an MPDCCH-PRB-set and determining a set of MPDCCH candidates in the determined MPDCCH-PRB-set according to an aggregation level, wherein a number of PRB-pairs in the MPDCCH-PRB-set is 2, 4 or 6; and monitoring the MPDCCH in the determined set of MPDCCH candidates to obtain downlink control information for an MTC UE.