SDMA Channel Activation in LTE Base Stations

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Solution Overview

Problem

Current Space Division Multiple Access (SDMA) technologies face limitations in efficiently multiplexing control and traffic channels, leading to suboptimal resource utilization and throughput in LTE and LTE-A systems, especially due to the complexity of interference cancellation and limited support for a large number of paired users in distributed antenna scenarios.

Innovation Solution

A method for communication using SDMA in an Evolved Node B (eNB) that dynamically determines whether to enable SDMA for channels based on traffic and control information thresholds, allocating resources such that data from users is transmitted only on the RRU(s) serving them when SDMA-enabled, and on all RRUs when SDMA-disabled, thereby optimizing resource allocation across different physical channels and signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If SDMA is enabled for all channels, then resource utilization and throughput are improved, but interference cancellation complexity increases and system reliability deteriorates

Engineering Contradiction:
ImprovethroughputVSAvoidinterference cancellation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the SDMA enabling/disabling decision adaptive rather than fixed. The eNB dynamically determines whether to enable SDMA for each channel based on real-time channel conditions, traffic load, and interference levels. This allows the system to optimize between throughput gain and interference cancellation complexity according to actual network state.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies local quality by treating different channels differently based on their specific characteristics. Instead of uniformly enabling SDMA for all channels, the system evaluates each channel's traffic information amount, control information amount, and interference conditions to make localized SDMA decisions. This resolves the contradiction by enabling SDMA only where beneficial while avoiding it where complexity would outweigh benefits.

Inventive Principle:
Principle #3Local quality

2Productivity

If SDMA is enabled to multiplex more users, then spectrum utilization improves, but the number of paired users is limited by processing power

Engineering Contradiction:
Improvespectrum utilizationVSAvoidBBU processing power requirement
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies partial action by enabling SDMA selectively rather than universally. The system evaluates whether the potential gain from multiplexing additional users justifies the increased processing requirements. When traffic load and channel conditions are favorable, SDMA is enabled to multiplex more users and improve spectrum utilization. When processing capacity is constrained or conditions are unfavorable, SDMA is disabled to avoid excessive processing requirements.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If SDMA is disabled for control channels, then interference is reduced, but resource utilization decreases

Engineering Contradiction:
Improveinterference reductionVSAvoidresource utilization
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by monitoring and comparing traffic information amounts and control information amounts against threshold values. Based on these parameter comparisons, the system dynamically adjusts the SDMA enabling state for each channel. When traffic load is high and control information is minimal, SDMA is enabled to improve resource utilization. When control information amount exceeds the threshold, SDMA is disabled to reduce interference and maintain reliability.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2575404B1Communication method using spatial division multiple access (SDMA), and base station
Publication Date: 2015.11.18 CHINA ACAD OF TELECOMM TECH
  • EP2575404B1 patent drawingFigure 1~2
  • EP2575404B1 patent drawingFigure 3
  • EP2575404B1 patent drawingFigure 4

AI summary

The present invention relates to the field of communications, and provides a communication method using spatial division multiple access (SDMA), to optimize an existing spatial division multiplexing mechanism. The method comprises: for each channel including a service channel and a control channel, according to a service information amount and/or a control information amount of the channel and a decision threshold corresponding to the channel, determining whether to activate SDMA for the channel; according to a decision result for a remote radio unit (RRU) to which each user belongs, allocating resources in an SDMA manner for the channel with the SDMA activated, and sending data of each user on the channel only on the RRU to which the user belongs; for a channel with the SDMA not activated, sending all data on the channel on all RRUs. The present invention is applicable to the spatial division multiplexing of various physical channels and physical signals specified by the standards of LTE and LTE-A systems, and can further improve utilization of resources in the system, the throughput of the system, and the data transmission rate.