Transmit Diversity Initialization for Random Access Channel Range Extension

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Solution Overview

Problem

In transmit diversity systems, the lack of feedback from the base station during initial negotiation with a mobile transmitter limits the effectiveness of beamforming, reducing the potential range extension and efficiency of communication, especially when using multiple sub-power amplifiers to conserve current.

Innovation Solution

A method that combines increasing transmission power with variations in transmit diversity parameters, such as phase difference and power ratio between antennas, to establish initial contact with the base station even without feedback, optimizing the beamforming process for range extension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If multiple sub-power amplifiers are used to conserve current, then power consumption is reduced, but the ability to establish initial contact with the base station is compromised due to insufficient transmission power

Engineering Contradiction:

Improvepower consumptionVSAvoidinitial contact establishment

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary actions by switching to a single full-power amplifier before probe transmission to ensure reliable initial contact with the base station. After successful registration, it transitions to using multiple sub-power amplifiers for normal operation, thus resolving the contradiction between power consumption and initial contact reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the amplifier configuration based on operational phase: using single full-power amplifier during initial access, then switching to multiple sub-power amplifiers during normal operation. This dynamic adaptation resolves the contradiction by optimizing power usage for each operational stage.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If transmit diversity parameters are adjusted without feedback from the base station, then initial negotiation can proceed, but beamforming effectiveness is reduced

Engineering Contradiction:

Improveinitial negotiation capabilityVSAvoidbeamforming effectiveness

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The system performs preliminary beamforming using predetermined phase relationships (e.g., 0, 90, 180, 270 degrees) before establishing feedback connection. This allows initial negotiation to proceed while preparing for optimized beamforming once feedback becomes available.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system transitions from open-loop transmit diversity during initial negotiation to closed-loop transmit diversity after base station registration, where feedback from the base station enables precise beamforming parameter adjustment, thus resolving the contradiction between initial negotiation capability and beamforming effectiveness.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8046017B2Method and apparatus for random access channel probe initialization using transmit diversity

Publication Date: 2011.10.25 GOOGLE LLC

AI summary

Embodiments of the present invention extend the benefits of mobile transmit diversity to the initialization phase of communication with a base station over a random access channel. According to a method of the invention, the transmitter may attempt to initiate communication with a receiver by varying a transmit diversity parameter, for example, phase difference, in addition to or instead of varying power settings.