Unified Bitmap for Precoding Matrix Subset Restriction
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Solution Overview
Problem
The existing multi-stage PMI feedback mechanism in wireless communications systems results in increased signaling overheads and wasted air interface resources due to the need for bitmaps to restrict precoding matrix selections, especially when dealing with varying parameter types corresponding to the precoding matrix W1 for different values of R.
Innovation Solution
A method is introduced where a base station determines and sends a field with T1 bits that indicate specific elements from sets B and Φ to form a precoding matrix, allowing user equipment to determine a subset of precoding matrices, thereby avoiding the use of restricted combinations and reducing signaling overheads by sharing a common field across different values of R.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-stage PMI feedback mechanism is used to reduce feedback overheads, then the precoding matrix selection capability is improved, but the signaling overhead increases due to multiple bitmaps being required
Solution Approach 1:
The patent combines multiple bitmaps (first bitmap for vector selection, second bitmap for phase difference selection) into a single unified bitmap. This unified bitmap uses different bit positions to indicate restrictions on different parameters (vectors and phase differences), thereby reducing the total signaling overhead while maintaining the ability to restrict precoding matrix selections across multiple stages.
Solution Approach 2:
The unified bitmap serves multiple functions simultaneously: it restricts vector selections, restricts phase difference selections, and indirectly restricts precoding matrix selections. This multi-functional approach eliminates the need for separate bitmaps for each restriction type, reducing overall signaling overhead.
2Manufacturing precision
If separate bitmaps are used to restrict vectors and phase differences, then the restriction precision is improved, but the field length increases greatly
Solution Approach 1:
The patent merges separate bitmaps for vector restriction and phase difference restriction into a single unified bitmap. The unified bitmap uses different bit positions to represent restrictions on different parameters, maintaining precise control over both vectors and phase differences while significantly reducing the total field length.
Solution Approach 2:
The patent introduces a new dimensional organization for the bitmap where different bit positions represent different restriction types (vector restrictions, phase difference restrictions) rather than using separate bitmaps. This reorganization in the bitmap structure allows precise restrictions to be encoded more compactly.
Data Source
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AI summary
A bit field indication manner is provided. A first field is determined, where the first field includes T1 bits, at least one of the T1 bits indicates at least two elements {bi0, bi1, ..., bik} in a set B, the at least one bit further indicates at least one element {θj0, θj1, ..., θjh} in a set Φ, and at least one element in {bi0, bi1, ..., bik} and at least one element in {θj0, θj1, ..., θjh} are used to form a precoding matrix, where the set B = {b0, b1, L, bT2-1}, an element in the set B is a vector with a length of N/4, the set Φ = {θ0,θ1,...,θS-1}, an element in Φ is a complex number of a unit amplitude, column l of the precoding matrix W satisfies some conditions, a quantity of rows of W is N, a quantity of columns of W is R, N is greater than or equal to R, bkl is an element in the set B, θpl is an element in the set Φ, ϕl is a complex number of a unit amplitude, T1, T2, and S are all positive integers, T1<S∗T2, and l is an integer greater than or equal to 0 and less than or equal to R-1.