Joint Transmission Power Normalization for Distributed MU-MIMO
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Solution Overview
Problem
Current wireless communication technologies using joint transmission (JT) in distributed multi-user MIMO systems face challenges in controlling the total power emitted by multiple antennas, which can exceed regulatory limits, potentially causing interference to incumbent services in unlicensed frequency bands.
Innovation Solution
Implementing a power normalization technique that scales the precoder output using a parameter NAP, indicating the number of access points (APs), to control the total power emitted by a plurality of antennas, thereby preventing power increases when additional APs are added.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If joint transmission is implemented with multiple APs to increase system capacity and coverage, then the total emitted power of the antenna system increases without limits, but this causes severe interference to incumbent services in unlicensed frequency bands
Solution Approach 1:
The patent changes the power parameter by introducing a normalization factor that divides the precoder output by the square root of the number of APs. This parameter transformation ensures that when N APs transmit simultaneously, each AP transmits at reduced power (1/√N scaling), keeping the total emitted power constant and preventing interference to incumbent services while maintaining joint transmission benefits
Solution Approach 2:
The patent implements dynamic power adjustment where the transmit power of each AP is adaptively scaled based on the number of participating APs in the joint transmission. The normalization factor dynamically adjusts the power level to maintain constant total power output regardless of the number of APs, resolving the contradiction between system expansion and interference control
2Reliability
If the number of antennas is increased by adding more APs to achieve better MIMO performance, then the total emitted power increases proportionally, but regulatory limits on power in unlicensed bands are exceeded
Solution Approach 1:
The patent transforms the power parameter by applying a normalization factor of 1/√N where N is the number of APs. This parameter change allows the system to maintain reliable MIMO performance through coordinated multi-AP transmission while keeping the total emitted power within regulatory limits by reducing individual AP power output proportionally
3Productivity
If full-power joint transmission is allowed to maximize data throughput, then the antenna system can achieve high productivity, but the aggregate emission levels increase and cause harmful interference to satellite services
Solution Approach 1:
The patent applies a power normalization parameter (division by √N) that transforms the power distribution across multiple APs. This parameter change enables the system to maintain high data throughput through joint transmission while controlling aggregate emission levels to protect satellite services, as the total power remains constant regardless of the number of participating APs
Data Source
AI summary
The present disclosure describes techniques for scaling the precoder output in an antenna system implementing joint transmission to control the total power emitted by a plurality of antennas distributed among multiple antennas. The scaling factor used for scaling the transmit power at each antenna comprises a parameter, NAP, indicating a number of APs in the antenna system. In introduction of the parameter, NAP, enables the scaling factor to be designed such that the total sum power does not increase when additional APs are added to the antenna system.