Proactive Allocation for TCP ACK Latency in 5G UEs
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Solution Overview
Problem
Current methods for reducing TCP ACK latency in Radio Access Networks (RANs) are complex and incomplete, particularly due to factors like user equipment (UE) time to access the network in uplink and stale Power Headroom Report (PHR) issues, leading to increased network latency and decreased download speeds.
Innovation Solution
A method that triggers proactive allocation windows for TCP ACK latency reduction in 5G New Radio (NR) and LTE systems, specifically for UEs with uplink inactivity, by estimating TCP ACK packet arrival time and size based on data packet transmissions, and enabling proactive allocation for the first TCP ACK packet, which is not possible with existing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If standard SR-based UE network access scheme is used, then device complexity is reduced, but TCP ACK latency increases by more than 11ms
Solution Approach 1:
The system performs preliminary estimation of TCP ACK packet arrival time and size before the actual ACK transmission. The eNB estimates when TCP ACK packets will arrive at the UE and proactively prepares uplink resources in advance, allowing the UE to transmit ACKs immediately upon receipt without waiting for SR/UL grant procedures.
Solution Approach 2:
The system enables self-service by allowing the UE to autonomously transmit TCP ACK packets using proactively allocated uplink resources without needing to go through the standard SR-based scheduling request process. The UE simply uses the pre-allocated resources when ACK packets are ready for transmission.
2Productivity
If SR periodicity is increased to support high capacity cells, then network capacity is improved, but TCP ACK latency increases significantly
Solution Approach 1:
The system proactively allocates uplink resources for TCP ACK transmission in advance, independent of SR periodicity. By estimating TCP ACK arrival times and preparing resources beforehand, the system decouples ACK transmission capability from SR scheduling periodicity, allowing high SR periodicity (80ms) to coexist with low TCP ACK latency.
3Reliability
If conservative MCS and TPC are used for UL grant without recent PHR report, then transmission reliability is improved, but TCP ACK transmission speed deteriorates
Solution Approach 1:
The system performs preliminary estimation of TCP ACK packet characteristics (size, arrival time) and uses this information to make informed decisions about resource allocation. By knowing in advance what ACK packets will arrive, the system can optimize MCS and TPC settings rather than using conservative defaults, improving both reliability and transmission speed.
Data Source
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AI summary
A method of reducing the transmission control protocol acknowledgment (TCP ACK) latency, e.g., in 5G New Radio (NR) or LTE system, is provided, which method is triggered, e.g., for user equipments (UEs) with uplink (UL) inactivity. The time estimation to find the TCP ACK packet arrival is based on estimation time split up in the UE side. In addition, the TCP ACK size estimation is based on the number of TCP data packets sent in Physical Downlink Shared Channel (PDSCH). Furthermore, the first "proactive allocation window" (the number of the transmission time intervals (TTIs) over which the proactive allocations are given to UE) is set to 4, and subsequently the "proactive allocation window" may be adapted based on learning.