Dynamic Uplink Carrier Switching for Random Access Latency

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Solution Overview

Problem

Existing methods for handling cell access in wireless communications networks, particularly in 5G systems using New Radio (NR), often result in UE failures and high latencies due to mismatched uplink and downlink carriers, leading to wasted resources and decreased network capacity.

Innovation Solution

A method allowing wireless devices to dynamically switch between Supplementary Uplink (SUL) and NR Uplink (NUL) carriers during an ongoing random access procedure based on criteria such as downlink Reference Signal Received Power (RSRP) thresholds and hysteresis, enabling optimal carrier selection for better coverage and reduced load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a UE selects an uplink carrier for random access based on a threshold, then the random access load can be offloaded between two UL carriers, but the UE may fail to access the cell or experience high latencies when path loss variations occur during the random access procedure

Engineering Contradiction:

Improverandom access success rateVSAvoidaccess reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent enables dynamic switching between uplink carriers (SUL and NUL) during the random access procedure based on real-time downlink RSRP measurements. Instead of fixing the carrier selection at the beginning, the UE continuously monitors RSRP and switches carriers when threshold conditions are met, making the system adaptive to changing channel conditions and reducing access failures

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback mechanism where the UE measures downlink RSRP during the random access procedure and uses this measurement feedback to determine whether to switch carriers. The network also provides feedback through thresholds and indications (e.g., sul-RSRP-Threshold, carrierSwitchingAllowed) that guide the UE's carrier selection and switching decisions, improving access reliability

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the UE sticks to the initially selected uplink carrier throughout the random access procedure, then the procedure is simpler to implement, but path loss variations cause UE failures and high latencies

Engineering Contradiction:

Improvecarrier selection simplicityVSAvoidrandom access latency

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent introduces dynamic carrier switching capability that allows the UE to change from the initially selected carrier to an alternative carrier when downlink RSRP measurements indicate better conditions on the other carrier. This dynamic adjustment reduces latency by enabling the UE to switch to a carrier with better propagation conditions without requiring complex manual reconfiguration

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters (carrier frequency, RSRP thresholds) based on measured conditions. The UE monitors RSRP values and compares them against configured thresholds to determine when to switch carriers, allowing the system to adapt to path loss variations by changing the operating carrier parameter

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the network provides detailed carrier switching configurations, then the UE can make optimal carrier selections, but the device complexity and processing requirements increase

Engineering Contradiction:

Improvecarrier selection accuracyVSAvoidcarrier management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent enables the UE to autonomously determine carrier switching decisions based on pre-configured thresholds and simple RSRP measurements. The network provides the necessary configuration parameters (thresholds, carrier indications), but the UE independently evaluates conditions and executes switching without complex network coordination, reducing overall system complexity while maintaining accurate carrier selection

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent uses configurable parameters (sul-RSRP-Threshold, carrierSwitchingAllowed, timeWindow) that allow the network to control the complexity level. By adjusting these parameters, the network can simplify or enhance carrier switching behavior based on deployment requirements, balancing selection accuracy with device complexity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3811717B1Wireless device and method performed thereby for handling access to a cell

Publication Date: 2023.01.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A method, performed by a wireless device (130), for handling access to a cell (120). The wireless device (130) operates in a wireless communications network (100). The wireless device (130) determines (302), given a first uplink carrier (141) in use during a random access procedure to the cell (120), whether or not a second uplink carrier (142) is to be used during the random access procedure to the cell (120), instead of the first uplink carrier (141). The cell (120) is served by a network node (110) operating in the wireless communications network (100). The wireless device (130) then uses (305), based on a result of the determination, one of the first uplink carrier (141) and the second uplink carrier (142), to continue the random access procedure to the cell (120).