PRACH Power Ramp-Up and Counter Logic in Power-Limited UEs
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Solution Overview
Problem
Current LTE technologies face challenges in efficiently managing PRACH transmission power ramp-up and counter incrementation, leading to potential power spikes and inefficient resource allocation, especially in power-limited scenarios.
Innovation Solution
The proposed solution involves a user equipment (UE) determining PRACH transmission power based on a power ramping stepsize and a previously unsuccessful transmission, with power scaling and threshold-based decisions to drop or transmit PRACH transmissions, and incrementing the Preamble_Transmission_Counter accordingly, ensuring gradual power ramp-up and efficient resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE increments the Preamble_Transmission_Counter for every PRACH transmission attempt, then the power ramp-up mechanism ensures that transmission power increases with each attempt, but this leads to excessive power consumption and potential power spikes in power-limited scenarios
Solution Approach 1:
The patent changes the parameter update rule by introducing a conditional check: the Preamble_Transmission_Counter and transmission power are only updated when the PRACH transmission is actually performed (not dropped). This conditional parameter update prevents unnecessary power ramping when transmissions are dropped due to power scaling, thereby reducing power consumption while maintaining transmission reliability for actual attempts
Solution Approach 2:
The patent makes the counter incrementing dynamic by linking it to the actual transmission execution rather than following a fixed increment rule. The counter only increments when the PRACH is transmitted, creating a dynamic adaptation mechanism that responds to actual transmission conditions and power availability, preventing rigid power spikes
2Use of energy by moving object
If the UE performs power scaling on concurrent PRACH transmissions, then power allocation is optimized for power-limited scenarios, but the interaction between power scaling and power ramp-up becomes complex and difficult to manage
Solution Approach 1:
The patent implements a self-service mechanism where the power ramp-up logic automatically adapts to power scaling decisions. The UE itself determines whether to update the counter and power level based on whether the transmission was dropped or executed, eliminating the need for separate complex coordination logic between power scaling and ramp-up mechanisms
Solution Approach 2:
The patent performs preliminary checks before updating power parameters. The UE evaluates whether the PRACH transmission will be dropped or executed before incrementing the counter or adjusting power, allowing proactive power management that simplifies subsequent power allocation decisions by pre-determining the appropriate power state
3Reliability
If the UE transmits PRACH at higher power levels to overcome poor channel conditions, then the probability of successful transmission increases, but this causes unnecessary power consumption when channel conditions are actually good
Solution Approach 1:
The patent introduces feedback-based power management where the transmission execution status (dropped or transmitted) feeds back into the power ramp-up decision. The UE uses this feedback to intelligently determine whether to increase power for the next attempt, avoiding blind power increases and enabling adaptive power control that responds to actual transmission outcomes and channel conditions
Data Source
AI summary
In a first configuration, a UE may determine a PRACH power ramp-up Pramp-up for the PRACH with respect to a previously unsuccessful PRACH transmission (e.g., a previously unsuccessful PRACH transmission with a highest transmission power). In a second configuration, when the UE is in a power-limited scenario, the UE drops/refrains from transmitting the PRACH transmission if Pramp-up−Pscal<Pdrop, and transmits the PRACH otherwise, where Pscal is the power scaling factor, Pramp-up is the configured ramp-up power value, and Pdrop is a threshold. In a third configuration, the UE determines whether to increment a Preamble_Transmission_Counter. In one sub-configuration, the UE increments the Preamble_Transmission_Counter when the PRACH transmission takes place, and does not increment the Preamble_Transmission_Counter otherwise. In another sub-configuration, the UE increments the Preamble_Transmission_Counter when the PRACH transmission takes place and Pramp-up−Pscal≥Pcount, where Pcount is a threshold, and does not increment the Preamble_Transmission_Counter otherwise.