UE Random Access Selection for Delay-Critical Scheduling Requests

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Solution Overview

Problem

In LTE networks, user equipment (UE) experiences significant latency when requesting uplink resources due to long scheduling request (SR) intervals, which is problematic for delay-critical data transmission, especially when the network fails to allocate PUSCH resources, leading to prolonged delays and inefficiencies in resource utilization.

Innovation Solution

The UE determines if the time to the next periodic transmission opportunity exceeds a threshold, allowing it to select between using an early random access procedure or the next periodic opportunity, and indicates the release of associated radio resources during the random access procedure, enabling faster access to PUSCH resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE uses periodic SR resources on PUCCH for uplink resource requests, then PUCCH resources are utilized for scheduled transmissions, but latency increases significantly when the SR interval is long (e.g., 80 ms)

Engineering Contradiction:

Improveresource allocation reliabilityVSAvoidSR latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the SR transmission mechanism adaptive rather than static. The UE dynamically selects between periodic PUCCH SR and random access RACH procedures based on real-time conditions including the time to next SR opportunity, delay criticality of data, and PUSCH allocation status. This dynamic selection resolves the contradiction by allowing the system to switch between reliable periodic scheduling and low-latency random access as needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of SR transmission timing by introducing an early RACH procedure that can be initiated before the next periodic SR opportunity when latency requirements demand it. The UE monitors whether the time to the next SR opportunity exceeds a threshold and, if so, initiates RACH early to obtain PUSCH resources immediately rather than waiting for the periodic SR cycle to complete.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the UE waits for the next periodic SR opportunity to request PUSCH resources, then resource allocation follows scheduled protocol, but delay critical data transmission is prolonged

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoiddata transmission delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the UE prepare and transmit the SR immediately via early RACH procedure when delay criticality is detected, rather than waiting for the scheduled SR opportunity. The UE proactively initiates the random access procedure in advance of the next periodic SR opportunity, obtaining PUSCH resources sooner and eliminating the waiting period that would otherwise be required by the periodic scheduling protocol.

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If the SR interval is extended to handle low activity UEs efficiently, then PUCCH resource usage is reduced, but latency for delay critical services increases

Engineering Contradiction:

ImprovePUCCH resource consumptionVSAvoidSR opportunity interval

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The patent applies universality by making the RACH procedure serve dual purposes: it functions as both a random access mechanism for initial uplink synchronization and as an early SR transmission mechanism for delay critical data. By allowing the RACH procedure to be used for SR transmission before periodic SR opportunities, the system maintains the benefit of extended SR intervals for low activity UEs while providing a fast path for delay critical services when needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP2745601B1Selection between random access and dedicated scheduling request resources

Publication Date: 2017.03.22 NOKIA TECHNOLOGIES OY

AI summary

In response to determining that a time to a periodic transmission opportunity exceeds a threshold, a UE selects between using a random access procedure and the periodic transmission opportunity to transmit an uplink message. In non-limiting examples given the periodic transmission opportunity is a scheduling request opportunity which is periodic according to an interval configured by a wireless network and the uplink message comprises a scheduling request. In an embodiment the user equipment's determination and selection is conditional on it pre-determining that intended uplink data or control signaling to which the scheduling request relates is delay sensitive. If that pre-determination is that the data/signaling is not delay sensitive then it uses the scheduling request opportunity to send its scheduling request without selecting between the random access procedure and the scheduling request opportunity.