HARQ Signaling Overhead Reduction in MIMO Systems
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Solution Overview
Problem
In spatial multiplexing wireless communications systems, the increased number of HARQ processes required due to MIMO technology leads to a significant increase in signaling overhead on the HS-SCCH, which is undesirable due to scarce signaling bits.
Innovation Solution
The method involves assigning a single re-transmission process identifier and disambiguation data for both data substreams during a transmission interval, allowing receivers to determine whether a re-transmitted transport block is scheduled for the primary or secondary substream, thereby reducing the number of bits needed for signaling from four to three per substream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate re-transmission process identifier is provided for each data substream in spatial multiplexing systems, then the receiver can accurately track and manage re-transmissions for each substream, but the signaling overhead on the HS-SCCH increases significantly
Solution Approach 1:
The patent merges the re-transmission process identifier into a single common identifier that applies to both data substreams. Instead of providing separate identifiers for primary and secondary substreams, the system uses one shared identifier that is disambiguated through additional signaling bits, thereby reducing the overall signaling overhead while maintaining reliable re-transmission tracking.
Solution Approach 2:
The patent resolves the identifier ambiguity by adding a disambiguation dimension. When the same re-transmission process identifier is used for both substreams, the system uses additional signaling information (disambiguation data) to indicate which substream the identifier refers to, effectively moving the differentiation from the identifier itself to a separate signaling dimension.
2Adaptability or versatility
If four bits are used for re-transmission process identification per substream, then sufficient identification capacity is provided, but the scarce signaling bits on HS-SCCH are consumed excessively
Solution Approach 1:
The patent combines the identification requirement for both substreams into a single three-bit identifier, reducing the total signaling bits from four bits per substream to three bits. The system maintains adaptability by using disambiguation data to resolve which substream the identifier refers to, thus reducing signaling bit consumption while preserving identification capacity.
3Loss of information
If a single re-transmission process identifier is used for both data substreams, then signaling overhead is reduced, but the receiver must determine which substream the re-transmission applies to
Solution Approach 1:
The patent resolves the substream determination difficulty by adding disambiguation data as an additional signaling dimension. When a single re-transmission process identifier is used for both substreams, the system provides extra bits (disambiguation data) that explicitly indicate which substream the identifier refers to, making the substream determination straightforward for the receiver without increasing overall complexity.
Data Source
AI summary
A method and apparatus for signaling scheduling information in a spatial multiplexing wireless communications system, as well as corresponding methods and apparatus for processing such signaling information, are disclosed. Signaling scheduling information includes scheduling first and second transport blocks for simultaneous transmission during a first transmission interval on first and second data substreams, respectively, and assigning a single re-transmission process identifier for the first transmission interval and transmitting first scheduling information for the first transmission interval. The first scheduling information includes the re-transmission process identifier and first disambiguation data. Additionally, at least one of the first and second transport blocks is scheduled for re-transmission during a second transmission interval. Second scheduling information for the second transmission interval is also transmitted; the second scheduling information including the re-transmission process identifier and second disambiguation data.