MIMO Reference Signal Transmission for Mixed Antenna UEs
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Solution Overview
Problem
In a Multiple Input Multiple Output (MIMO) communication system, existing technologies face challenges in effectively transmitting data and reference signals when a user equipment (UE) capable of supporting N antennas coexists with another UE capable of supporting M antennas, where M > N, without additional signaling with the old UE recognizing only N antennas.
Innovation Solution
The method involves dividing the radio frame into separate transmission intervals for supporting N antennas and up to M antennas, restricting UEs recognizing only N antennas to transmit data only in the interval supporting N antennas, and signaling information about these intervals to UEs capable of recognizing up to M antennas, allowing them to transmit in either interval while ensuring correct channel information recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reference signals for M antennas are transmitted in a subframe, then the M-antenna UE can obtain channel information, but the N-antenna UE (where N < M) cannot correctly recognize the reference signals and experience performance deterioration
Solution Approach 1:
The patent segments the set of M reference signals into two groups: the first N reference signals correspond to the N antennas that both N-antenna and M-antenna UEs can support, while the remaining M-N reference signals correspond to the additional antennas that only M-antenna UEs can support. This segmentation allows N-antenna UEs to correctly identify and process their supported reference signals while M-antenna UEs can access all M reference signals, thereby resolving the contradiction between adaptability and reliability.
2Productivity
If additional reference signals are transmitted to support M antennas, then M-antenna UE performance improves, but system complexity increases due to the need to manage different antenna support scenarios
Solution Approach 1:
The patent creates a universal reference signal transmission scheme where the base station transmits M reference signals that serve dual purposes: the first N reference signals serve both N-antenna and M-antenna UEs, while the remaining M-N reference signals serve M-antenna UEs. This multi-functional approach allows the system to support multiple antenna configurations simultaneously without requiring separate signaling mechanisms for different UE types, thereby improving productivity while managing device complexity.
3Reliability
If the system transmits reference signals for N antennas only, then N-antenna UEs can correctly recognize them, but M-antenna UEs cannot obtain channel information for the additional M-N antennas
Solution Approach 1:
The patent applies preliminary action by having the base station pre-configure and transmit all M reference signals (including both the first N and the remaining M-N reference signals) in advance, before any UE needs to perform channel estimation. This allows N-antenna UEs to use the first N reference signals for their channel estimation while M-antenna UEs can simultaneously use all M reference signals to obtain channel information for all their supported antennas, thereby preventing information loss without compromising recognition accuracy.
Data Source
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AI summary
A reference signal transmission method in a downlink MIMO system is disclosed. The downlink MIMO system supports a first UE supporting N transmission antennas among a total of M transmission antennas (where M > N) and a second UE supporting the M transmission antennas. The method includes transmitting, by a base station (BS), subframe-associated information which designates a first subframe in which data for the first UE and the second UE is transmitted and a second subframe in which data only for the second UE can be transmitted within a radio frame having a plurality of subframes, and transmitting the first subframe and the second subframe. Reference signals corresponding to antenna ports '0' to 'N-1' of the N antennas are mapped to the first subframe, and reference signals corresponding to antenna ports '0' to 'M-1' of the M antennas are mapped to the second subframe.