Precoding Vector Selection for Multi-Point MIMO Throughput
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Solution Overview
Problem
In wireless communication systems, Multi-Point HSDPA operations with two MIMO streams from the same sector/cell result in a loss in sector throughput and do not provide useful gains in throughput, due to the limitation of maximum multiplex gain being two, which restricts spatial multiplexing and transmit diversity capabilities.
Innovation Solution
Restricting the selection of precoding vectors to only rank 1 precoding vectors during multi-point downlink transmissions from different sector antenna arrays to prevent spatial multiplexing, while allowing any precoding vector of rank 1 or higher during single-point MIMO communications to enable spatial multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two MIMO streams are transmitted from the same sector/cell in Multi-Point HSDPA operations, then the spatial multiplexing capability is increased, but the sector throughput is reduced due to the maximum multiplex gain limitation of two
Solution Approach 1:
The patent applies local quality by differentiating the MIMO transmission strategy based on the operational mode: in single-point transmission mode, full MIMO capabilities (up to 2 streams) are utilized to maximize spatial multiplexing gain, while in multi-point transmission mode, MIMO is restricted to 1 stream to avoid throughput degradation. This localized adaptation of transmission parameters to specific operational contexts resolves the contradiction between spatial multiplexing capability and sector throughput.
2Productivity
If precoding vectors of rank 2 or higher are selected during multi-point downlink transmissions, then spatial multiplexing gain is increased, but compatibility and performance are degraded due to spatial multiplexing incompatibilities
Solution Approach 1:
The patent implements dynamics by making the precoding vector selection adaptive to the transmission mode. The system dynamically adjusts the maximum precoding rank based on whether single-point or multi-point transmission is active: rank 2 or higher is permitted in single-point mode to achieve spatial multiplexing gain, while rank 1 is enforced in multi-point mode to ensure compatibility. This dynamic parameter adjustment resolves the contradiction between data rate and transmission compatibility.
3Productivity
If spatial multiplexing is enabled during multi-point operations, then data rate is increased, but system performance is degraded due to spatial multiplexing incompatibilities
Solution Approach 1:
The patent applies parameter changes by modifying the MIMO transmission parameters (specifically the number of spatial streams and precoding rank) based on the operational mode. In multi-point transmission mode, the system changes the parameter to 1 spatial stream to eliminate spatial multiplexing incompatibilities, while in single-point mode, it changes the parameter to up to 2 streams to maximize data rate. This parameter adaptation resolves the contradiction between data rate and system performance.
Data Source
AI summary
Methods may be provided to operate wireless terminal in wireless communication networks providing multiple-input-multiple-output (MIMO) downlink communications from a plurality of base station sector antenna arrays using a codebook of precoding vectors. Such methods may include receiving multi-point MIMO downlink communications from the wireless communication network. When receiving the multi-point MIMO downlink communications from the wireless communication network, a precoding vector may be selected from a subset of the precoding vectors of the codebook for the multi-point MIMO downlink communications.