# 陳毅 - 讀書會 - 21/07/24

:::info
- [x] 閱讀 Netmanias-07-LTE QoS - SDF and EPS Bearer QoS
:::

## Abbreviations
- AMBR Aggregated Maximum Bit Rate
- ARP Allocation and Retention Priority DL Downlink
- GBR Guaranteed Bit Rate
- MBR Maximum Bit Rate
- PCC Policy and Charging Control
- PF Packet Filter
- QCI QoS Class Identifier
- SDF Service Data Flow
- SPR Subscriber Profile Repository
- TFT Traffic Flow Template

## SDF and EPS Bearer


The SDF and EPS bearer are detected by matching the IP flows against the packet filters:
- SDF templates for SDFs or traffic
- flow templates (TFTs) for EPS bearers

These packet filters are pre-configured by network operators in accordance with their policy, and each of them typically consists of 5-tuple (Source IP address, Destination IP address, Source port number, Destination port number, and Protocol ID).

### SDF

User traffic using different services (or applications) has different QoS class. A SDF is an IP flow or an aggregation of IP flows of user traffic classified by the type of the service in use.

### Terms relating to SDFs and EPS Bearers


## QoS Parameters for SDF and EPS Bearer

在 LTE 網路中， QoS 參數可以被區分為：
### Service level (SDF level)
SDF QoS parameters 為 Service level ，主要包含：
1. GBR SDF QoS parameters: QCI, ARP, GBR (UL/DL) and MBR (UL/DL)
2. Non-GBR SDF QoS parameters: QCI, ARP and MBR (UL/DL)

- ARP
- GBR
- MBR
### Bearer level (SDF aggreagate level)
> SDF aggreagate = 擁有相同 QCI 的 SDFs Group 。

EPS bearer parameters 為 Bearer level ，主要包含：
1. GBR bearer QoS parameters: QCI, ARP, GBR(UL/DL) and MBR(UL/DL)
2. Non-GBR bearer QoS parameters: QCI, ARP, APN-AMBR(UL/DL) and UE-AMBR(UL/DL)

#### AMBR
AMBR which means dedicated network resources are not allocated to the bearer, but a maximum bandwidth to share with other non-GBR bearers that is allocated.
其中 AMBR 可以再分為兩類：
1. APN-AMBR
是在 PDN 中由所有的 non-GBR 乘載共享的最大頻寬
2. UE-AMBR
由於一個 UE 可以連到不止一個 PDN ，這也代表所有 PDN 的總 APN-AMBR 不能大於 UE-AMBR 。
### SDF and EPS Bearer QoS Parameters


### QoS Parameters for SDF and EPS Bearer


### GBR vs. Non-GBR

## QoS Provisioning and Enforcement
### SDF QoS Provisioning
All the QoS parameters for SDFs are provisioned by PCRF.
### EPS Bearer QoS Provisioning
QoS parameters applied to a default bearer are provisioned to an HSS as subscription by a network operator.
### QoS Enforcement
During QoS enforcement, detection of user traffic (IP flows i.e., SDF and EPS bearer) is performed and then QoS rules are applied to each of the detected SDFs and EPS bearers accordingly.
#### SDF QoS Enforcement
SDF QoS parameters (i.e. QCI, ARP, MBR and GBR) are installed in a P-GW.
#### EPS Bearer QoS Enforcement
QoS parameters for EPS bearers are enforced in EPS entities (UE, eNB, S-GW and P-GW) that deliver user traffic between UE and P-GW.

## An Example for SDF and EPS Bearer QoS
Through the examples, a description of how the SDF QoS and EPS bearer QoS mechanisms work and what they do in each EPS entity will be given. The scenario used for the purposes of this chapter is as follows:
- UE connected to one PDN (Internet)
- UE communicating with the Internet through three bearers, i.e. one default bearer, one non-GBR dedicated bearer, and one GBR dedicated bearer.
- Their bearer IDs (EPS bearer ID (EBI)) are 5, 8 and 10, respectively.

### QoS Operation in Downlink


1. IP flows 下行
2. 使用 SDF Templates 對資料進行過濾
3. MBR Policing
4. 使用 Traffic flow Templates 對資料進行過濾
5. MBR/APN-AMBR Policing
6. UE-AMBR Policing

### QoS Operation in Uplink


1. IP flows 上行

2. 使用 Traffic flow Templates 對資料進行過濾
上行IP数据流被IP数据包过滤TFT过滤为EPS承载。在这里，IP和TCP/UDP协议头中的五元组用于过滤规则。IP数据流1/2映射到GBR专用承载EBI=10，IP数据流3/4被映射到non-GBR专用承载EBI=8，IP数据流5被映射为默认承载EBI=5.

3. MBR/APN-AMBR Policing
EPS承载QoS应用于每一个EPS承载。对于映射到GBR专用承载EBI=10的IP数据流，使用上行的MBR来执行速率策略，对于non-GBR专用承载EBI=5/8的所有IP数据流使用上行APN-AMBR来执行速率策略。

4. MBR/APN-AMBR Policing
eNB对GBR承载EBI=10使用上行MBR执行速率策略和调度，对于non-GBR承载EBI=5/8使用上行UE-AMBR来执行速率策略和调度。认为只有一个PDN，上行UE-AMBR和上行APN-AMBR是相等的。

5. EPS Bearer 到達 P-GW

6. MBR/APN-AMBR Policing

7. 使用 SDF Templates 對資料進行過濾
EPS bearers are filtered through IP packet filters (SDF templates) into different SDFs. IP flows 1 and 2 from
the GBR dedicated bearer (EBI=10) are mapped to SDFs 1 and 2, IP flows 3 and 4 from non-GBR dedicated
bearer (EBI=8) are mapped to SDFs 3 and 4, and finally IP flows 5 from the default bearer (EBI=5) is
mapped to SDF 5.

8. MBR Policing