8-Antenna Downlink Control Channel Weighting for Coverage
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Solution Overview
Problem
Current methods for transmitting a downlink control channel using 8 antennas in TD-LTE base stations face inefficiencies, particularly in the 2-port based weighted broadcast scheme, where power distribution leads to reduced coverage area compared to FDD base stations with 2 antennas, due to suboptimal weighting of antennas.
Innovation Solution
The method involves virtualizing pairs of dual-polarized antennas into specific ports with balanced broadcast weights (+1 and -1) to optimize the transmission of a downlink control signal, allowing for extended coverage by effectively utilizing the 8 antennas as if they were 2 ports with enhanced power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the 2-port based weighted broadcast scheme is used to transmit downlink control channel on 8 antennas, then the pilot overhead is reduced, but the coverage area cannot be achieved compared to FDD base station with 2 antennas due to power loss from suboptimal antenna weights
Solution Approach 1:
The patent changes the antenna weight parameters from suboptimal values (some below 1) to optimal values (+1 or -1), which eliminates power loss while maintaining the 2-port structure. This allows the system to achieve both low pilot overhead and sufficient coverage area.
Solution Approach 2:
The patent introduces asymmetric weight assignments where one antenna in each pair has weight +1 and the other has weight -1, creating complementary transmission patterns that extend coverage while maintaining the reduced pilot overhead benefit of the 2-port scheme.
2Area of stationary object
If the 4-port based scheme (SFBC plus FSTD) is used to transmit downlink control channel on 8 antennas, then the coverage area can be improved, but the pilot overhead becomes considerable due to occupation of CRSs of 4 ports
Solution Approach 1:
The patent merges the functionality of 4 antenna ports into 2 virtual ports by combining antenna pairs with complementary weights. This reduction to 2 ports eliminates the need for 4 sets of CRS pilots, significantly reducing pilot overhead while maintaining coverage through optimized weight distribution.
3Power
If 8 antennas are grouped into 2 ports with 4 antennas per port in the weighted broadcast scheme, then the power per port is increased, but the weights on some antennas are below 1 resulting in power loss
Solution Approach 1:
The patent optimizes the antenna weight parameters from suboptimal values (some below 1) to optimal values (+1 or -1), which eliminates power loss while maintaining the 2-port structure. This allows the system to achieve both low pilot overhead and sufficient coverage area.
Data Source
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AI summary
A sending method and device for an 8-antenna downlink control channel, comprising: for eight antennas used for downlink transmission of a base station, virtualizing a first pair and a third pair of dual-polarized antennas as a first port, and virtualizing a second pair and a fourth pair of dual-polarized antennas as a second port, wherein weighted values of the broadcast right of the four antennas in the first port satisfy that the weighted value of one antenna is +1 and the weighted values of the other three antennas are -1, or the weighted value of one antenna is -1 and the weighted values of the other three antennas are +1, and weighted values of the broadcast right of the four antennas in the second port satisfy that the weighted value of one antenna is +1 and the weighted values of the other three antennas are -1, or the weighted value of one antenna is -1 and the weighted values of the other three antennas are +1; and the base station sending downlink control signals through the first port and the second port. The method can expand the coverage of the downlink control channel of the base station using eight antennas.