PDSCH Transport Block Size Determination for MTC Coverage Enhancement
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Solution Overview
Problem
In the context of 3GPP LTE and LTE-Advanced, machine-type communication (MTC) devices face challenges in receiving downlink channels, particularly in coverage extension areas where special subframes and synchronization signals reduce available resources, leading to inconsistent transport block sizes and difficulties in decoding PDSCH across multiple subframes.
Innovation Solution
A method for determining transport block sizes in PDSCH based on the actual number of physical resource blocks (PRBs), where low-cost/low-capability devices and those configured for coverage enhancement receive the same PRBs in both downlink and special subframes, ensuring consistent decoding across multiple subframes, and a wireless device with a transceiver and processor calculates PRBs and transport block sizes to handle overlapping resources with synchronization signals and broadcast channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the base station repeatedly transmits the same downlink channel on multiple subframes for coverage extension, then the coverage area is extended, but the transport block size becomes inconsistent when special subframes are involved, leading to decoding failures
Solution Approach 1:
The patent changes the parameter used for transport block size determination from the actual number of allocated PRBs to a calculated number of PRBs that excludes resources occupied by synchronization signals and broadcast channels. This parameter change ensures consistent TBS calculation across normal and special subframes, enabling reliable decoding of repeatedly transmitted downlink channels in coverage extension scenarios.
2Productivity
If the base station uses special subframes for downlink transmission, then the downlink capacity is increased, but the available resources for PDSCH transmission are reduced due to synchronization signals and broadcast channels
Solution Approach 1:
The patent applies preliminary action by calculating the number of PRBs available for PDSCH transmission in advance, taking into account the resources occupied by synchronization signals and broadcast channels in special subframes. This pre-calculation allows the wireless device to correctly determine the transport block size before reception, ensuring that the full downlink capacity of special subframes is utilized while maintaining accurate resource accounting.
3Productivity
If the wireless device calculates transport block size based on the actual number of allocated PRBs, then the resource utilization is maximized, but the transport block size varies between normal and special subframes, causing decoding failures in repeated transmissions
Solution Approach 1:
The patent changes the parameter for TBS determination from the actual allocated PRBs to a calculated PRB count that represents the maximum available resources. This parameter change creates a stable reference that remains consistent across normal and special subframes, ensuring that repeatedly transmitted channels have the same TBS and can be successfully decoded.
Solution Approach 2:
The patent uses the calculated number of PRBs as a standardized copy that represents the maximum resource allocation, which is then used consistently for TBS determination in both normal and special subframes. This copying approach ensures that the TBS remains stable across different subframe types while still allowing full resource utilization in each transmission.
Data Source
AI summary
A method for determining a transport block size includes including determining a number of physical resource blocks (PRBs) based on a value smaller than a total number of PRBs allocated for a physical downlink shared channel (PDSCH), based on that the device is a first device and based on that the PDSCH is to be received on a time division duplex (TDD)-based special subframe, determining the number of PRBs to be the same as the total number of PRBs allocated for the PDSCH, based on that the device is a second device, which is related to a low-complexity device or which is configured for a coverage enhancement (CE), and determining the transport block size in the PDSCH based on the determined number of PRBs.