Scheduling Request Throttling for Multi-SIM Wireless Devices

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Solution Overview

Problem

Multi-SIM wireless communication devices often experience Radio Resource Control (RRC) mismatches when switching between subscriptions, leading to connectivity issues and unnecessary power consumption due to the assumption of remaining connected to a base station, even after a long tune-away, resulting in the transmission of a full default count of scheduling requests.

Innovation Solution

Implementing a method to throttle the maximum count of scheduling requests based on the tune-away time interval, adjusting the count inversely proportional to the length of the interval, and initiating an uplink data Random Access Channel process if no uplink grant is received, thereby reducing power and time consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wireless communication device transmits the full default count of scheduling requests after a long tune-away, then the device ensures maximum uplink grant opportunities, but the device consumes unnecessary power and time monitoring the prohibit timer and transmitting requests that will not be recognized by the base station

Engineering Contradiction:
Improveuplink grant receptionVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the scheduling request count adaptive rather than static. The device dynamically adjusts the number of scheduling requests to transmit based on the duration of the tune-away period. For longer tune-away periods, the device transmits fewer scheduling requests (e.g., 1-3 requests instead of the full default count of 64), while for shorter tune-away periods, it transmits the full default count. This dynamic adjustment resolves the contradiction by optimizing power consumption while maintaining reliable uplink grant reception when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of scheduling request count based on the tune-away time interval. The device monitors the length of the tune-away period and adjusts the scheduling request transmit count accordingly. This parameter change allows the device to reduce power consumption by transmitting fewer requests after long tune-aways (where the base station would not recognize the C-RNTI) while maintaining full transmission capability after short tune-aways (where connection is likely maintained).

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the wireless communication device transmits the full default count of scheduling requests after a long tune-away, then the device maximizes uplink communication opportunities, but the device experiences data stalls due to RRC mismatch and base station not recognizing the C-RNTI

Engineering Contradiction:
Improveuplink data transmissionVSAvoiddata stall time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the scheduling request count adaptive rather than static. The device dynamically adjusts the number of scheduling requests to transmit based on the duration of the tune-away period. For longer tune-away periods, the device transmits fewer scheduling requests (e.g., 1-3 requests instead of the full default count of 64), while for shorter tune-away periods, it transmits the full default count. This dynamic adjustment resolves the contradiction by optimizing power consumption while maintaining reliable uplink grant reception when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies partial action by transmitting only a portion of the default scheduling requests after long tune-away periods. Instead of transmitting all 64 default requests, the device transmits a reduced number (1-3 requests) when the tune-away exceeds a threshold. This partial action is sufficient to detect whether the base station recognizes the C-RNTI, avoiding the excessive action of transmitting all requests that would result in data stalls and wasted time.

Inventive Principle:
Principle #16Partial or excessive action

3Device complexity

If the wireless communication device assumes it is still connected to the base station after a long tune-away, then the device maintains connection state simplicity, but the device causes RRC mismatch and connectivity issues with the base station

Engineering Contradiction:
Improveconnection state managementVSAvoidRRC connection status
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing a connection status check before transmitting scheduling requests. The device determines whether the tune-away period exceeds a threshold that would cause RRC mismatch, and only then transmits a reduced number of scheduling requests. This preliminary assessment prevents RRC mismatch issues by avoiding transmission of requests that the base station would not recognize, while maintaining simple connection state management through threshold-based decision logic.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies feedback by monitoring the base station's response to scheduling requests. If the base station does not provide an uplink grant in response to transmitted scheduling requests, the device infers that it has experienced RRC mismatch and adjusts its behavior accordingly. This feedback mechanism allows the device to adapt to connection status changes without complex state management, resolving the contradiction between simplicity and reliability.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3398396B1Scheduling request throttling for multi subscriber identity module (SIM) wireless communication device
Publication Date: 2021.07.28 QUALCOMM INC
  • EP3398396B1 patent drawingFigure 1
  • EP3398396B1 patent drawingFigure 2
  • EP3398396B1 patent drawingFigure 3

AI summary

Apparatuses and methods are described herein for a wireless communication device to request uplink grants associated with the first subscription using at least one Radio Frequency (RF) resource, including tuning away from the first subscription to the second subscription for a tune-away time interval, determining whether the tune-away time interval exceeds a threshold, transmitting at least one scheduling request associated with the first subscription for a throttled count in response to the tune-away time interval exceeding the threshold, wherein the throttled count is less than a default count, determining whether an uplink grant has been received in response to any of the at least one scheduling request transmitted within the throttled count, and initiating an uplink data Random Access Channel (RACH) process in response to not receiving the uplink grant.