Orthogonal Polarization Reference Signals for Beam Selection
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Solution Overview
Problem
In 5G wireless communication systems, particularly at ultra-high frequency bands like mmWave, beamforming techniques face challenges in determining optimal beam direction and polarization for indoor terminals, leading to varying transmission losses across different polarizations, which affects data quality and reception gain.
Innovation Solution
The system transmits multiple reference signals with different polarizations simultaneously, allowing for feedback to determine an optimal combination of beam direction and polarization, thereby enhancing data quality and reducing transmission losses by using orthogonal polarizations and covering codes to distinguish between signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If beamforming technique is used to increase signal gain, then transmission loss is reduced, but transmission loss varies significantly according to polarizations causing difficulty in determining optimal beam direction and polarization
Solution Approach 1:
The reference signals are segmented by polarization type, with different cyclic shifts assigned to different polarizations. This allows the system to separately identify and evaluate performance for each polarization, enabling selection of the optimal polarization for the current channel conditions while maintaining beamforming gain.
Solution Approach 2:
The base station preliminarily transmits reference signals with different polarizations and cyclic shifts before actual data transmission. The terminal measures these signals in advance to determine the optimal polarization and report it back, allowing the beamforming parameters to be optimized beforehand for the specific channel conditions.
2Measurement precision
If multiple reference signals with different polarizations are transmitted, then optimal polarization can be determined, but system complexity increases
Solution Approach 1:
Instead of transmitting multiple independent reference signals with different polarizations, the system changes the cyclic shift parameter of a single reference signal sequence to represent different polarizations. This parameter-based differentiation allows the terminal to distinguish between polarizations without requiring multiple separate signal transmissions, thereby reducing system complexity while maintaining measurement accuracy.
3Productivity
If reference signals for different polarizations are transmitted in the same time resource, then transmission efficiency is improved, but signal differentiation becomes difficult
Solution Approach 1:
The system replaces physical signal differentiation (using separate time resources or frequency resources) with mathematical differentiation through cyclic shifts. By applying different cyclic shifts to the reference signal sequence for different polarizations, the terminal can easily differentiate and measure each polarization's channel characteristics using simple correlation operations, maintaining transmission efficiency while enabling signal differentiation.
Data Source
AI summary
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). According to various embodiments of the present disclosure, an apparatus of a base station of a wireless communication system may comprise at least one transceiver, and at least one processor operatively coupled to the at least one transceiver. The at least one processor is configured to transmit, to a terminal, a plurality of reference signals including a first plurality of reference signals corresponding to a first polarized wave and a second plurality of reference signals corresponding to a second polarized wave, and receive feedback information indicative of at least one reference signal of the plurality of reference signals, wherein the first plurality of reference signals respectively correspond to a plurality of beams, the second plurality of reference signals respectively correspond to the plurality of beams, and the second polarized wave may be orthogonal to the first polarized wave.