Four-Branch MIMO Transport Format and Resource Combination
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Solution Overview
Problem
Current four-branch MIMO systems in HSDPA face challenges in efficiently managing transport blocks and codewords, particularly when user equipment reports higher rank information, as existing mechanisms are restricted to using only two codewords for four antennas, limiting performance.
Innovation Solution
A method is introduced where a radio base station determines a transport format and resource combination (TFRC) based on received rank information and channel quality indicators, allowing for the transmission of multiple MAC-ehs PDUs with specific sizes, handled by hybrid automatic repeat request processes, to optimize data transmission in four-branch MIMO systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two codewords are mapped to four antennas in a four-branch MIMO system, then the system is easier to implement and define in 3GPP standard, but the system cannot properly handle higher rank information (RI >= 3) and is limited in achieving 336 Mbps on four carriers
Solution Approach 1:
The patent segments the four transmit antennas into two groups, each group handling one codeword. This segmentation allows the system to maintain two codewords while supporting up to four layers through spatial multiplexing within each codeword, thereby enabling higher rank information support without increasing the number of codewords beyond two.
Solution Approach 2:
The patent introduces a new dimension of spatial multiplexing within each codeword by utilizing the four antennas to transmit up to four layers. This dimensional approach allows the system to achieve higher rank information support (up to rank 4) while maintaining the two-codeword structure, effectively solving the limitation without compromising ease of implementation.
2Stability of the object's composition
If the maximum transport block size is limited to 42192 bits, then the current system structure is maintained, but the system cannot achieve 336 Mbps on four carriers with four-branch MIMO
Solution Approach 1:
The patent segments the data transmission across multiple transport blocks, where each transport block can be up to 42192 bits. By utilizing up to four transport blocks simultaneously across four antennas with two codewords, the system achieves higher aggregate data rates (up to 336 Mbps on four carriers) while maintaining the maximum transport block size limitation for each individual block.
3Ease of operation
If one to one mapping is used for transport blocks to layers for rank 1 and rank 2, then the mapping is simple, but this approach cannot be used for higher ranks due to the restriction of using only two codewords
Solution Approach 1:
The patent segments the layer mapping process into two stages: first, mapping transport blocks to codewords (one-to-one for up to two transport blocks), and second, mapping codewords to layers through spatial multiplexing across the four antennas. This segmented approach maintains simplicity for rank 1 and 2 while enabling support for higher ranks up to 4.
Solution Approach 2:
The patent introduces codewords as an intermediary between transport blocks and layers. Instead of directly mapping transport blocks to layers (which is limited by the one-to-one relationship), the system uses codewords as an intermediate layer that can be spatially multiplexed across multiple antennas, thereby enabling higher rank information support while maintaining mapping simplicity.
Data Source
AI summary
Improved performance of downlink data transmission in a high speed downlink packet access, HSDPA, mobile communication system is described. Rank information, RI, and channel quality information, CQI, is obtained in a radio base station from a user equipment, UE, and this rank and CQI information is used in a medium access control-ehs, MAC-ehs, entity for determining a transport format and resource combination, TFRC, on a downlink channel.