Random Access Response Format for Beam Failure Recovery

Solution Overview

Problem

Current random access procedures in wireless communication networks, particularly in 5G networks, face inefficiencies due to high MAC overhead during beam failure recovery, leading to increased energy consumption and reduced network coverage.

Innovation Solution

A method where user equipment (UE) and radio network nodes optimize the random access response (RAR) by omitting the temporary cell radio network temporary identifier (T-C-RNTI) during beam failure recovery, using an improved RAR format that includes only the uplink grant and timing advance command, reducing unnecessary MAC overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the random access response (RAR) includes the temporary cell radio network temporary identifier (T-C-RNTI) during beam failure recovery, then the random access procedure can be completed with standard formatting, but the MAC overhead increases leading to higher energy consumption and reduced network coverage

Engineering Contradiction:

Improvenetwork coverageVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts and removes the T-C-RNTI field from the random access response message during beam failure recovery procedures. Since the UE is already in connected mode with an existing C-RNTI, the temporary identifier is unnecessary and its removal reduces MAC overhead, thereby reducing energy consumption and improving network coverage in coverage-limited scenarios.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the format parameter of the random access response by conditionally omitting the T-C-RNTI field based on the UE's connection state. When the UE is in connected mode, the RAR uses a compact format without T-C-RNTI, while in idle mode it uses the standard format with T-C-RNTI, thus optimizing overhead based on operational parameters.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the random access response (RAR) includes the temporary cell radio network temporary identifier (T-C-RNTI), then the message format remains standardized and compatible, but the MAC overhead increases reducing communication efficiency

Engineering Contradiction:

Improvecommunication efficiencyVSAvoidMAC overhead

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent extracts and removes the T-C-RNTI field from the random access response message during beam failure recovery procedures. Since the UE is already in connected mode with an existing C-RNTI, the temporary identifier is unnecessary and its removal reduces MAC overhead, thereby reducing energy consumption and improving network coverage in coverage-limited scenarios.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the format parameter of the random access response by conditionally omitting the T-C-RNTI field based on the UE's connection state. When the UE is in connected mode, the RAR uses a compact format without T-C-RNTI, while in idle mode it uses the standard format with T-C-RNTI, thus optimizing overhead based on operational parameters.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If an improved RAR format without T-C-RNTI is used during beam failure recovery, then MAC overhead is reduced and energy consumption decreases, but the message format becomes non-standard requiring special handling

Engineering Contradiction:

Improveenergy consumptionVSAvoidmessage format handling

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by having the UE indicate its connection state (connected or idle) before transmitting the random access preamble during beam failure recovery. This allows the network to pre-determine the appropriate RAR format, avoiding the need for complex post-processing and interpretation of non-standard formats, thus reducing the complexity burden on both UE and network side.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where the UE's connection state information is used to determine the RAR format. The network receives feedback about the UE state and accordingly selects the appropriate message format, enabling efficient handling of the improved format without requiring complex interpretation logic.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11528767B2User equipment, radio network node and methods performed therein for handling communication in a wireless communication network

Publication Date: 2022.12.13 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Embodiments herein disclose, e.g., a method performed by a user equipment, UE, for handling communication in a wireless communication network, wherein the UE is in a connected mode in a first beam connected to a radio network node. The UE detects a beam failure of the first beam and transmits, to the radio network node, a preamble of a random access procedure in a second beam, wherein the preamble or a random access resource used for the preamble is associated with a beam failure recovery. The UE then receives a random access response, RAR, from the radio network node, wherein the RAR includes an uplink, UL, grant but without a temporary identity that is used by a medium access control, MAC, entity during a random access procedure.