Adaptive Random Access Channel Retransmission Power Control

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Solution Overview

Problem

Mobile wireless devices face challenges in balancing power consumption and communication performance during uplink random access channel preamble transmissions, particularly due to variable interference and signal quality, leading to potential early termination of calls and increased battery drain.

Innovation Solution

A method and apparatus that adapt power levels and repetitions of uplink preamble transmissions based on measured downlink signal quality, using parameters from the wireless network to determine initial transmit power and limit retransmissions when the required power exceeds the maximum allowed, thereby optimizing power usage and reducing interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mobile wireless device transmits preambles with increasing power levels up to maximum power level, then the call origination request can be completed under variable interference conditions, but the battery power consumption increases significantly

Engineering Contradiction:

Improvecall completionVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the transmit power level adaptive rather than fixed. The mobile device dynamically adjusts the power level for each preamble transmission based on the downlink signal quality measurements, transitioning from a static maximum power approach to a dynamic power control mechanism that responds to channel conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the power level parameter based on measured downlink signal quality. By monitoring parameters such as received signal code power (RSCP), received signal strength indicator (RSSI), and received signal to noise/interference ratio (Ec/Io), the device modifies the transmit power parameter adaptively, reducing power when downlink quality is poor and allowing higher power when conditions permit

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the mobile wireless device limits the number of preamble retransmissions to conserve battery power, then power consumption decreases, but the connection opportunity is lost

Engineering Contradiction:

Improvebattery power consumptionVSAvoidconnection success rate

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements feedback by having the mobile device measure downlink signal quality and use this information to determine the appropriate number of retransmissions. The feedback loop continuously monitors channel conditions and adjusts the retransmission strategy accordingly, allowing the device to distinguish between temporary interference and persistent poor conditions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by measuring downlink signal quality before initiating the preamble transmission sequence. This advance measurement allows the device to pre-determine the optimal number of retransmissions needed, avoiding unnecessary transmissions that would waste battery power while ensuring sufficient attempts to overcome temporary interference

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the mobile wireless device uses high transmit power levels, then the preamble can be received under poor signal conditions, but radio frequency interference increases

Engineering Contradiction:

Improvesignal receptionVSAvoidradio frequency interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the transmit power parameter dynamically based on actual channel conditions. Instead of consistently using high power levels, the device adjusts power parameter values according to measured downlink signal quality, using higher power only when necessary to overcome path loss and lower power when interference would be unnecessary

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8718667B2Adaptive random access channel retransmission

Publication Date: 2014.05.06 APPLE INC

AI summary

A mobile wireless device adapts transmit power levels and number of retransmissions of a preamble sent to a wireless network. The mobile wireless device measures characteristics of a downlink signal received from the wireless network. The mobile wireless device transmits a series of preambles to the wireless network, each successive preamble having an increased power level, starting at a power level based on the measured received signal characteristics and on parameters received from the wireless network, up to a maximum transmit power level. When the transmit power level of the preamble exceeds the maximum transmit power level and when the measured downlink signal quality falls below a threshold, the mobile wireless device limits the number of preamble retransmission to less than an allowed maximum number of retransmissions. A minimum number of retransmissions is determined and adapted to higher values for larger measured values of downlink signal quality.