PUCCH Scheduling Requests to Reduce Random Access Overhead

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Solution Overview

Problem

The excessive use of random access procedures for scheduling requests in wireless networks leads to inefficient resource utilization, increased latency, and reduced network capacity due to the conservative transport formats and limited simultaneous support of RACH procedures, particularly in scenarios where dedicated PUCCH resources are not configured or have been released.

Innovation Solution

A wireless communication device refrains from initiating a random access procedure for scheduling requests by utilizing pre-configured PUCCH resources indicated in an RLC PDU, allowing higher layer processing to complete before transmitting the RLC status report, thereby reducing the need for immediate SR over RACH.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a WCD sends SR via random access procedure (RACH), then UL grant can be obtained without dedicated PUCCH resources, but random access procedure utilization increases leading to resource consumption and latency

Engineering Contradiction:

Improveability to send SR without dedicated PUCCH resourcesVSAvoidlatency in obtaining UL grant

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The network configures PUCCH resources for SR transmission in advance through RRC signaling (RRCReconfiguration message). When the WCD needs to send an SR, it can immediately use the pre-configured PUCCH resources without initiating a random access procedure, thereby reducing latency while maintaining the ability to send SRs even when no dedicated resources were initially available.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If a WCD sends SR via random access procedure (RACH), then UL grant can be obtained without dedicated PUCCH resources, but network resource consumption increases

Engineering Contradiction:

Improveability to send SR without dedicated PUCCH resourcesVSAvoidnetwork resource consumption

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The network performs preliminary configuration of PUCCH resources through RRC signaling before the WCD needs to send SRs. This advance preparation allows the WCD to use efficient PUCCH-based SR transmission instead of consuming more resources-intensive random access procedures, thereby reducing overall network resource consumption while maintaining adaptability.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If RACH procedure is used for SR transmission, then connection setup and UL timing synchronization can be established, but cell capacity and spectrum efficiency are impacted

Engineering Contradiction:

Improveconnection setup and UL timing synchronizationVSAvoidcell capacity and spectrum efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network configures PUCCH resources in advance through RRC reconfiguration messages sent during connection setup or reconfiguration phases. Once configured, the WCD can reliably send SRs using these pre-established PUCCH resources, avoiding the need to repeatedly use RACH procedures for SR transmission, thereby preserving cell capacity and spectrum efficiency while maintaining reliable connection management.

Inventive Principle:

Principle #10Preliminary action

4Productivity

If dedicated PUCCH SR resource is configured after RRC reestablishment or resume, then SR can be sent efficiently, but WCD may have already transmitted SR via RACH before receiving the configuration

Engineering Contradiction:

ImproveSR transmission efficiencyVSAvoiddelay in receiving UL grant

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system dynamically manages SR transmission by allowing WCD to send SR via RACH when no PUCCH resources are configured, and automatically transitions to PUCCH-based SR transmission once the network sends RRCReconfiguration with dedicated PUCCH resources. The WCD monitors for this reconfiguration message and switches transmission methods accordingly, optimizing efficiency while accounting for the dynamic state of resource configuration.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12635024B2Systems and methods for reducing utilization of a random access procedure for scheduling request transmission in a wireless network

Publication Date: 2026.05.19 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Systems and methods of the present disclosure are directed to a method. The method includes transmitting a Radio Resource Control (RRC) request or Scheduling Request (SR) via a random access procedure. The method includes receiving a Radio Link Control (RLC) Protocol Data Unit (PDU) including a RLC header and a RRC message, wherein the RLC header has an indication of an instruction to transmit an RLC status report. The method includes, responsive to transmitting, making a determination that a Wireless Communication Device (WCD) is to refrain from transmitting a SR via the random access procedure. The method includes, responsive to making the determination, transmitting a SR on Physical Uplink Control Channel (PUCCH) resource(s) of the PUCCH resource(s) indicated in the RRC message to obtain an uplink grant to transmit the RLC status report for the RLC PDU.