Method for coexistence of low latency, low loss and scalable throughput (L4S) and non-L4S traffic in 5G-type networks
A method for optimizing coexistence of low latency, low loss and scalable throughput (L4S) traffic and non-L4S traffic in a 5G wireless system is provided, which method includes one of: a) performing one of i) a flow control between a centralized unit (CU) and a distributed unit (DU), or ii) radio resource management at the DU, to reduce latency experienced by the L4S traffic; or b) performing one of iii) a flow control between the CU and the DU to facilitate greater frequency of transmission of non-L4S traffic from CU-user plane (CU-UP) to the DU, or iv) radio resource management at the DU, to reduce a scheduling priority metric of a logical channel for the L4S traffic relative to a scheduling priority metric of a logical channel for the non-L4S traffic. To reduce latency of the L4S traffic, the L4S traffic scheduling priority is increased relative to the non-L4S traffic.
1 . A method for optimizing coexistence of low latency, low loss and scalable throughput (L4S) traffic and non-L4S traffic in a 5G wireless system serving a user equipment (UE), comprising
one of:
a) performing one of i) a flow control between a centralized unit (CU) and a distributed unit (DU), or ii) radio resource management at the DU, to adjust latency experienced by the L4S traffic; or
b) performing one of iii) a flow control between the CU and the DU to facilitate greater frequency of transmission of non-L4S traffic from CU-user plane (CU-UP) to the DU, or iv) radio resource management at the DU, to adjust a scheduling priority metric of a logical channel for the L4S traffic relative to a scheduling priority metric of a logical channel for the non-LAS traffic;
wherein the scheduling priority P LC non-L4S of each non-L4S logical channel is computed using at least the following factors:
W 5QI , which is the weight of P 5QI , which is in turn a priority metric corresponding to a quality of service (QoS) class of the respective logical channel;
W GBR , which is the weight of P GBR , which is in turn a priority metric corresponding to a target bit rate of the respective logical channel;
W PDB , which is the weight of P PDB , which is in turn a priority metric corresponding to a packet delay budget at the DU for the respective logical channel, and
W PF , which is the weight of P PF , which is in turn a priority metric corresponding to a proportional fair metric of the UE;
wherein the scheduling priority P LC non-L4S of each non-L4S logical channel is computed as follows:
P
L
C
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o
n
-
L
4
S
=
(
W
5
QI
*
P
5
Q
I
+
W
PF
*
P
P
F
)
*
maximum
(
W
GBR
*
P
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B
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,
W
PDB
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P
P
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n
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;
wherein P PDB non-L4S is the priority metric corresponding to a packet delay budget at the DU for the respective non-L4S logical channel.
2 . The method of claim 1 , wherein the scheduling priority P LC L4S of each L4S logical channel is computed using at least the following factors:
W 5QI ;
W GBR ;
W PDB ;
W PF ;
WL4S 5QI , which is the weight of P 5QI for the respective L4S logical channel;
WL4S GBR , which is the weight of P GBR for the respective L4S logical channel;
WL4S PDB , which is the weight of P PDB for the respective L4S logical channel; and
WL4SPF, which is the weight of P PF for the respective L4S logical channel.
3 . The method of claim 2 , wherein the scheduling priority P LC L4S of each L4S logical channel is computed as follows:
P
L
C
L
4
S
=
(
WL
4
S
5
QI
*
W
5
QI
*
P
5
Q
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+
W
L
4
S
PF
*
W
PF
*
P
P
F
)
*
maximum
(
WL
4
S
GBR
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W
GBR
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P
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W
L
4
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PDB
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PDB
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P
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;
wherein P PDB L4S is the priority metric corresponding to a packet delay budget at the DU for the respective L4S logical channel.
4 . The method of claim 3 , wherein, to adjust the latency experienced by the L4S traffic, the radio resource management at the DU is performed to adjust the scheduling priority metric of the logical channel for the L4S traffic relative to the scheduling priority metric of the logical channel for the non-L4S traffic.
5 . The method of claim 3 , wherein at least one of the following is performed at the DU to facilitate fair coexistence of a non-L4S data radio bearer (DRB) and an L4S DRB:
i) for a non-guaranteed bit rate (non-GBR) L4S DRB, WL4S GBR is set to 0;
ii) for a non-GBR, non-L4S DRB, W GBR is set to 0;
iii) for a GBR, L4S DRB, WL4S GBR is set to be less than or equal to 1;
iv) WL4S PF is set to be greater than or equal to 1; and
v) WL4S 5QI is set to be less than or equal to 1, and WL4S PDB is set to be less than or equal to 1.
6 . The method of claim 3 , wherein at least one of the following is performed:
i) for non-L4S traffic, P PDB non-L4S is set to 1 if PDB DU is less than or equal to QDelay RLC , and P PDB non-L4S is set to 1/(PDB DU −QDelay RLC ) if PDB DU is greater than QDelay RLC , wherein PDB DU is a packet delay budget at the DU for a respective logical channel, and QDelay RLC is radio link control (RLC) queuing delay defined as a delay of the oldest RLC packet in the QoS flow that has not been scheduled yet; and
ii) for L4S traffic, P PDB L4S is set to 1 if PDB DU is less than or equal to QDelay RLC , and P PDB L4S =max[n/(PDB DU −QDelay RLC ), 1] if PDB DU is greater than QDelay RLC , wherein n is the number of packets which have been in the RLC queue for a specified time interval.
7 . The method of claim 3 , wherein at least one of the following is performed:
i) for non-L4S traffic, P PDB non-L4S is set to 1 if PDB DU is less than or equal to QDelay RLC , and P PDB non-L4S is set to 1/(PDB DU −QDelay RLC ) if PDB DU is greater than QDelay RLC , wherein PDB DU is a packet delay budget at the DU for a respective logical channel, and QDelay RLC is radio link control (RLC) queuing delay defined as a delay of the oldest RLC packet in the QoS flow that has not been scheduled yet; and
ii) for L4S traffic, Pppp is set to 1 if PDB DU is less than or equal to QDelay RLC , and P PDB L4S =1/[(PDB DU −QDelay RLC )*(PDB DU −QDelay RLC,2 )] if PDB DU >QDelay RLC and the RLC queue has at least two packets, wherein QDelay RLC,2 is the delay of the second oldest RLC packet in the QoS flow that has not been scheduled yet.
8 . The method of claim 1 , wherein, for non-L4S data radio bearers (DRBs) and L4S DRBs that are mapped to radio link control Unacknowledged Mode (RLC UM), the following are performed:
for non-L4S traffic, expiration of a first periodic timer having a first duration is used as a trigger for sending downlink data delivery status (DDDS) message from the DU to the CU-UP; and
for non-L4S traffic, expiration of a second periodic timer having a second duration different from the first duration is used as a trigger for sending downlink data delivery status (DDDS) message from the DU to the CU-UP.
9 . The method of claim 8 , wherein the first duration is greater than the second duration.
10 . The method of claim 8 , wherein the second duration is greater than the first duration.
11 . The method of claim 1 , wherein, for non-L4S data radio bearers (DRBs) and L4S DRBs that are mapped to radio link control Acknowledged Mode (RLC UM), the following are performed:
for non-L4S traffic, sending of downlink data delivery status (DDDS) message from the DU to the CU-UP is triggered at the expiration of a first periodic timer having a first duration or upon receipt of RLC status Protocol Data Unit (PDU), whichever occurs first; and
for L4S traffic, sending of DDDS message from the DU to the CU-UP is triggered at the expiration of a second periodic timer having a second duration different from the first duration or upon receipt of RLC status PDU, whichever occurs first.
12 . The method of claim 11 , wherein the first duration is greater than the second duration.
13 . The method of claim 11 , wherein the second duration is greater than the first duration.
14 . The method of claim 4 , wherein at least one of the following is performed at the DU to facilitate fair coexistence of a non-L4S data radio bearer (DRB) and an L4S DRB:
i) for a non-guaranteed bit rate (non-GBR) L4S DRB, WL4S GBR is set to 0;
ii) for a non-GBR, non-L4S DRB, W GBR is set to 0;
iii) for a GBR, L4S DRB, WL4S GBR is set to be less than or equal to 1;
iv) WL4S PF is set to be greater than or equal to 1; and
v) WL4S 5QI is set to be less than or equal to 1, and WL4S PDB is set to be less than or equal to 1.