TCP Uplink Performance During Radio Resource Multiplexing
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Solution Overview
Problem
Wireless devices that multiplex radio resources between multiple radio access technologies (RATs) face challenges in managing TCP uplink performance due to frequent resource shifts, leading to inappropriate re-transmission attempts and congestion recovery mechanisms triggered by mistaken poor RF conditions.
Innovation Solution
Providing indications to the TCP layer when radio resources are switched away from and back to the primary RAT, and implementing a re-transmission timeout guard-interval to suspend and resume the uplink re-transmission timer accordingly, avoiding unnecessary re-transmissions and congestion recovery mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single radio is shared between multiple wireless technologies, then device cost and power consumption are reduced, but radio resource conflicts and TCP performance degradation occur
Solution Approach 1:
A radio resource management entity acts as an intermediary between the TCP layer and the shared radio system. This intermediary monitors radio resource allocation status and provides indications to the TCP layer when resources are multiplexed away from the primary RAT, enabling the TCP layer to suspend retransmission timers appropriately and prevent performance degradation while maintaining the energy-efficient shared radio architecture
2Device complexity
If radio resources are multiplexed between multiple RATs, then device complexity is reduced, but TCP re-transmission errors increase due to frequent resource shifts
Solution Approach 1:
The system implements a feedback mechanism where the radio resource management entity continuously monitors the allocation status of the shared radio between multiple RATs and provides real-time indications to the TCP layer. When the radio is multiplexed away from the primary RAT, the TCP layer receives feedback to suspend its retransmission timer, preventing false detection of packet loss and avoiding unnecessary re-transmissions, thereby maintaining reliable packet delivery despite frequent resource shifts
3Reliability
If TCP re-transmission timer is continuously active, then packet delivery reliability is maintained, but unnecessary re-transmissions occur during radio resource shifts
Solution Approach 1:
The TCP retransmission timer is made dynamic rather than continuously active. The timer is suspended when radio resources are multiplexed away from the primary RAT and resumed when resources are returned to the primary RAT. This dynamic adjustment prevents unnecessary re-transmissions during resource shifts (improving bandwidth efficiency) while maintaining packet delivery reliability through appropriate timer management, as the timer is reactivated when the radio becomes available again
Data Source
AI summary
Improving transmission control protocol (TCP) uplink performance of a wireless user equipment (UE) device which multiplexes radio resources between multiple radio access technologies (RATs). Radio control may be provided to a radio resource control (RRC) entity that operates according to a first RAT at a first time. The first RAT may utilize TCP packet-switched (PS) communications. As a second time, radio control may be provided to an RRC entity that operates according to a second RAT which utilizes circuit-switched communications in order to check for paging messages. Radio control by the first RAT's RRC entity may be suspended while radio control is provided to the second RAT's RRC entity. An indication that radio control by the first RAT's RRC entity is suspended may be provided to a TCP entity that operates according to the first RAT. The TCP entity may suspend an uplink retransmission timer in response to the indication.