TCP acknowledgment latency optimization
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.
1. A method for reducing Transmission Control Protocol Acknowledgement (TCP ACK) latency by estimating a time of TCP ACK packet arrival in one of a 5G New Radio (NR) and a Long Term Evolution (LTE) system, comprising:
estimating a first delay timer (DelayTimer #1) as a sum of time for user equipment (UE) feedback for downlink (DL) data, time for TCP application ACK response, and time for UE uplink (UL) application and L3 processing;
starting a first proactive allocation window comprising the number of transmission time intervals (TTIs) over which proactive allocations are given to the UE following the first delay timer; and
estimating a second delay timer (DelayTimer #2) as a sum of the time for UE feedback for DL data, the time for TCP application ACK response, the time for UE UL application and L3 processing, and time for Start Delay Offset parameter representing a timing mismatch between a first proactive allocation slot of the first proactive allocation window and an actual proactive allocation slot of the first proactive allocation window in which the data is received.
2. The method according to claim 1 , further comprising:
adapting the size of a second proactive allocation window based on learning using the Start Delay Offset parameter.
3. The method according to claim 2 , wherein:
in the case 4 proactive allocations are provided in the proactive allocation window, if PUSCH data is received for the third allocation, the delay timer is advanced by two TTIs to match UE TCP ACK timing.
4. The method according to claim 1 , wherein the method is applied to a Long Term Evolution (LTE) system using synchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ feedback transmission from Evolved NodeB (eNB) to the user equipment (UE),
the eNB does not send a Negative Acknowledgement (NACK) for padded data sent by the UE with an error in the proactive allocation window.
5. The method according to claim 1 , wherein the method is applied to a Long Term Evolution (LTE) system using synchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ feedback transmission from Evolved NodeB (eNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if padding data transmitted by the UE in any one of the four proactive allocation slots is in Cyclic Redundancy Check (CRC) error, and the eNB has already received an intended Transmission Control Protocol Acknowledgement (TCP ACK) before a subframe in which synchronous retransmission occurs, then the eNB does not send a Negative Acknowledgement (NACK).
6. The method according to claim 1 , wherein the method is applied to a Long Term Evolution (LTE) system using synchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ feedback transmission from Evolved NodeB (eNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if the UE i) sends padding data in the first proactive allocation slot (Alloc #1) provided in the proactive allocation window, ii) sends in the second proactive allocation slot (Alloc #2) provided in the proactive allocation window the actual data which is in Cyclic Redundancy Check (CRC) error, and iii) sends padding data in the third and fourth proactive allocation slots (Alloc #3 and Alloc #4) provided in the proactive allocation window, then the proactive allocation window size is not extended, thereby allowing the UE to at least one of a) recover from the CRC error, b) send a Scheduling Request (SR) and c) transmit a Transmission Control Protocol Acknowledgement (TCP ACK).
7. The method according to claim 1 , wherein the method is applied to a Long Term Evolution (LTE) system using synchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ feedback transmission from Evolved NodeB (eNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if at least one of i) padding data transmitted by UE in any one of the four proactive allocation slots is in Cyclic Redundancy Check (CRC) error, ii) the UE is not able to catch up with the proactive allocation window size, and iii) padding data is transmitted in the fourth proactive allocation slot (Alloc #4) provided in the proactive allocation window without Buffer Status Report (BSR), then the eNB sends ACK as HARQ feedback for the padding data.
8. The method according to claim 1 , wherein the method is applied to a Long Term Evolution (LTE) system using synchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ feedback transmission from Evolved NodeB (eNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if all four proactive allocation slots are in Cyclic Redundancy Check (CRC) error, the proactive allocation window size is not extended, thereby allowing the UE to at least one of a) recover from the CRC error, b) send a Scheduling Request (SR) and c) transmit a Transmission Control Protocol Acknowledgement (TCP ACK).
9. The method according to claim 1 , wherein the method is applied to a 5G New Radio (NR) system using asynchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ retransmission trigger from Next generation nodeB (gNB) to the user equipment (UE),
the gNB does not send DCI 0_0/0_1 with any retransmission for any padded data sent by the UE with error in the proactive allocation window.
10. The method according to claim 1 , wherein the method is applied to a 5G New Radio (NR) system using asynchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ retransmission trigger from Next generation nodeB (gNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if padding data transmitted by UE in any one of the four proactive allocation slots is in Cyclic Redundancy Check (CRC) error, and the gNB has already received an intended Transmission Control Protocol Acknowledgement (TCP ACK) before a subframe in which intended asynchronous retransmission is to be triggered by the gNB, then the gNB does not trigger the retransmission for a corresponding Physical Uplink Shared Channel (PUSCH).
11. The method according to claim 1 , wherein the method is applied to a 5G New Radio (NR) system using asynchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ retransmission trigger from Next generation nodeB (gNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if the UE i) sends padding data in the first proactive allocation slot (Alloc #1) provided in the proactive allocation window, ii) sends in the second proactive allocation slot (Alloc #2) provided in the proactive allocation window the actual data which is in Cyclic Redundancy Check (CRC) error, and iii) sends padding data in the third and fourth proactive allocation slots (Alloc #3 and Alloc #4) provided in the proactive allocation window, then the proactive allocation window size is not extended, thereby allowing the UE to at least one of a) recover from the CRC error, b) send a Scheduling Request (SR) and c) transmit a Transmission Control Protocol Acknowledgement (TCP ACK).
12. The method according to claim 1 , wherein the method is applied to a 5G New Radio (NR) system using asynchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ retransmission trigger from Next generation nodeB (gNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if at least one of i) padding data transmitted by UE in any one of the four proactive allocation slots is in Cyclic Redundancy Check (CRC) error, ii) the UE is not able to catch up with the proactive allocation window size, and iii) padding data is transmitted in the fourth proactive allocation slot (Alloc #4) provided in the proactive allocation window without Buffer Status Report (BSR), then the gNB sends ACK as HARQ feedback for the padding data.
13. The method according to claim 1 , wherein the method is applied to a 5G New Radio (NR) system using asynchronous Hybrid Automatic Repeat Request (HARQ) in uplink (UL), and wherein to control Medium Access Control (MAC) layer HARQ retransmission trigger from Next generation nodeB (gNB) to the user equipment (UE), the following is performed:
in the case of four proactive allocation slots provided in the proactive allocation window, if all four proactive allocation slots are in Cyclic Redundancy Check (CRC) error, the proactive allocation window size is not extended, thereby allowing the UE to at least one of a) recover from the CRC error, b) send a Scheduling Request (SR), and c) not trigger retransmit Downlink Control Information (DCI).
14. The method according to claim 1 , further comprising:
adapting Outer Loop Rate Control (OLRC) algorithm by performing the following:
in the case of four proactive allocation slots provided in the proactive allocation window, at least one of i) if all four proactive allocation slots are in Cyclic Redundancy Check (CRC) error, and if a padding data is received in at least one of the proactive allocation slots, then not update the Acknowledgment (ACK) response in the OLRC Step Up calculation, and ii) if intended data packet is received in at least one of the proactive allocation slots, and Hybrid Automatic Repeat Request (HARQ) process status and OLRC are active, then update the ACK and Negative Acknowledgment (NACK) responses in the OLRC Step Up and Step Down calculations.