Transport Block Size Determination Using PRB Offset in LTE eCCH
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Solution Overview
Problem
In LTE telecommunications systems, the mismatch between the assumed and actual number of OFDM symbols for downlink data transmissions leads to unsuitable modulation and coding schemes, resulting in reduced data throughput and increased retransmissions due to excessive or sub-optimal code rates.
Innovation Solution
Incorporating a PRB offset value or adjustment factor in determining the transport block size to avoid unsuitable modulation and coding schemes, allowing for better scheduling of downlink data transmissions and achieving increased data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transport block size is determined based on the total number of allocated PRBs without PRB offset, then the scheduling is simple, but unsuitable modulation and coding schemes are selected leading to reduced data throughput
Solution Approach 1:
The patent modifies the transport block size determination by introducing a PRB offset parameter that adjusts the effective number of PRBs used for calculation. This parameter change enables suitable modulation and coding scheme selection while maintaining scheduling algorithm simplicity, thereby increasing data throughput without significantly complicating the scheduling process.
2Reliability
If the transport block size is determined using all allocated PRBs, then resource utilization is maximized, but excessive code rates are used leading to transmission failures and retransmissions
Solution Approach 1:
The patent applies partial action by using only a portion of the allocated PRBs (N_PRB - O_PRB) for transport block size determination instead of all allocated PRBs. This partial utilization prevents excessive code rates and transmission failures while maintaining sufficient data throughput by reserving the offset PRBs for control channel overhead.
3Productivity
If PRB offset is incorporated in transport block size determination, then suitable modulation and coding schemes are selected increasing throughput, but the scheduling algorithm becomes more complex
Solution Approach 1:
The patent performs preliminary action by pre-determining the PRB offset value based on control channel configuration before the actual scheduling decision. This preliminary determination simplifies the operational complexity during scheduling by having the offset value ready, requiring only a simple subtraction from the total allocated PRBs to get the effective PRBs for transport block calculation.
Data Source
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AI summary
A method in a user equipment (121) for determining a transport block size is provided. The transport block size is used by the user equipment (121) in receiving downlink data transmissions from a network node (110) on an enhanced Control CHannel, eCCH. The user equipment (121) and the network node (110) are comprised in a telecommunications system (100). The user equipment (121) has access to a table of predetermined transport block sizes. The user equipment (121) may calculate an indicator NPRB based on the total number of PRBs allocated to the downlink data transmission N'PRB, and based on an PRB offset value OPRB or a PRB adjustment factor APRB. Then, the user equipment (121) may determine the transport block size from the table of predetermined transport block sizes based on at least the calculated indicator NPRB. A user equipment, a method in network node and a network node are also provided.