Operator Logo

Product Type Technical Proposal

PS Service Performance Optimization(Delay)

R1.1

LEGAL INFORMATION

By accepting this certain document of ZTE CORPORATION you agree to the following terms. If you do not agree to the following terms, please notice that you are not allowed to use this document.Copyright 2011 ZTE CORPORATION. Any rights not expressly granted herein are reserved. This document contains proprietary information of ZTE CORPORATION. Any reproduction, transfer, distribution, use or disclosure of this document or any portion of this document, in any form by any means, without the prior written consent of ZTE CORPORATION is prohibited. and are registered trademarks of ZTE CORPORATION. ZTEs company name, logo and product names referenced herein are either trademarks or registered trademarks of ZTE CORPORATION. Other product and company names mentioned herein may be trademarks or trade names of their respective owners. Without the prior written consent of ZTE CORPORATION or the third party owner thereof, anyones access to this document should not be construed as granting, by implication, estopped or otherwise, any license or right to use any marks appearing in the document.The design of this product complies with requirements of environmental protection and personal security. This product shall be stored, used or discarded in accordance with product manual, relevant contract or laws and regulations in relevant country (countries).This document is provided as is and as available. Information contained in this document is subject to continuous update without further notice due to improvement and update of ZTE CORPORATIONs products and technologies.

ZTE CORPORATION

Address:NO. 55Hi-tech Road SouthShenZhenP.R.China518057

Website:http://dms.zte.com.cn (Technical Support)

Email:TSM.Aftersales@zte.com.cn

Revision HistoryProduct VersionDocument VersionSerial NumberReason for Revision

R1.0First published

R1.1Adds one chapter, Introduction to Other Typical Data Service Application.

AuthorDateDocument VersionPrepared byReviewed byApproved by

2009-07-20R1.0Yang YongZheng HaoWang Ning

2011-03-02R1.1Yang YongZheng HaoWang Ning

Intended audience: GSM network optimization engineersProposal: Before reading this document, you had better have the following knowledge and skills.SEQKnowledge and skillsReference material

1NullNull

2

3

Follow-up document: After reading this document, you may need the following information.SEQReference materialInformation

1GPRS Radio Parameter SettingNull

23GPP ProtocolNull

3

About This DocumentSummaryChapterDescription

1 OverviewIntroduces the data service protocol system.

2 Signaling Flow DelayIntroduces the mobility management flow delay and session management flow delay.

3 Data Flow DelayIntroduces the data service flow delay.

4 Introduction to Other Typical Data Service ApplicationsIntroduces the Fetion and MMS service delay.

TABLE OF CONTENTS11Overview

22Signaling Flow Delay

22.1Mobility Management Flow Delay

62.2Session Management Flow Delay

93Data Flow Delay

114Introduction to Other Typical Data Service Applications

114.1Fetion

114.1.1Fetion (Between Terminals)

124.1.2Fetion (Between IM Terminals)

134.1.3Introduction to Fetion Service Delay

144.2MMS Service

144.2.1Introduction to MMS Service

154.2.2Introduction to MMS Service Delay

FIGURES1Figure 11 PS Service Protocol System

3Figure 21 Mobility Management Flow

4Figure 22 Attach Flow Including the TBF Establishment Procedure

7Figure 23 MS Session Management Model

7Figure 24 Standard PDP Activation Flow

11Figure 41 Fetion Service Flow

12Figure 42 Fetion Service Communication Flow

14Figure 43 MMS Service Flow

1 OverviewIn order to understand PS service delay, you should first know the common PS service flows. The most common PS service flows are the mobility management flow, session management flow, and typical application service flow. In the following chapters, we will analyze how the delay of the key flows produce and give adjustment suggestions to reduce the delay so as to improve the users perception.

According to the protocol, the common PS service flows can be divided into signaling flow and data flow. Each flow varies with protocols. The following figure shows the protocol system of the PS service. The mobility management flow and session management flow belong to signaling flow and typical application service flow belongs to data flow. For other signaling flow, see 3GPP23.060.Figure 11 PS Service Protocol System

2 Signaling Flow Delay2.1 Mobility Management Flow DelayPS service mobility management happens between the MS and the SGSN. Each mobility management status has its functions and information. The messages sent between the MS and the SGSN are called mobility management message.

For the GPRS MS, there are three mobility management status: idle, standby, and ready.

Idle to ready: The MS establishes the logical link between the MS and the SGSN through active flow.

Standby to idle: The MS or the SGSN initiates to delete the mobility management message and the PDP message in the SGSN and the GGSN; or the HLR notifies the SGSN to delete the LAC.

Standby to ready: The MS sends the LLC PDU data to the SGSN. The SGSN receives the LLC PDU data to be sent to the MS.

Ready to standby: Relevant counter times out; the SGSN forces the MS to enter standby status; data transmission is abnormal after cell reselection.

Ready to idle: The MS or the SGSN initiates to delete the mobility management message and the PDP message in the SGSN and the GGSN. Or the HLR notifies the SGSN to delete the location of the MS. The mobility management flow is as shown in the following figure.Figure 21 Mobility Management Flow

Attach is the most important mobility management flow, in which the Attach flow initiated by the MS is the most common. The following part describes how the delay is produced in the Attach flow initiated by the MS.Attach delayFigure 22 Attach Flow Including the TBF Establishment Procedure

1.After Attach flow starts, pay attention to the setting of the test interval. For the running ZTE network, the uplink extensible TBF counter is large and uplink delay exists. If the Attach test interval is relatively small and the second Attach test needs to be started, the MS will release the TBF reserved for the last service before sending the ATTACH REQUEST message on the RACH.The timing is counts from the sending of the ATTACH REQUEST message, therefore, time will be consumed and the result will be affected.

2.After the Channel Request message is sent, the uplink TBF link establishment begins. In this phase, if the network enables the one-stage access function of the TBF, the test time will be saved by about 400-500 ms. The delay of TBF establishment is related to the link transmission delay and the processing time of different equipment.

The differences of signaling flow of one-stage access and two-stage access are shown below.

3.After the uplink TBF establishment, the MS will send the ATTACH REQUEST message to the SGSN, and the network will start the downlink TBF establishment, send the authorization encryption requests, and start the authorization and encryption process. It will take about 100 ms from the successful downlink TBF establishment to the MS sending the authorization encryption request. The time is to establish the downlink TBF when the uplink TBF exists.

4.The authorization and encryption process in the Attach flow happens between the MS and the SGSN. It takes less than 200 ms. The process is the basis of all services and is not recommended to be cancelled. For other services, the authorization and encryption process can be cancelled.

5.After the authorization and encryption process is complete, the network will send the ATTACH ACCEPT message which takes about 300 ms if the test is not performed across the SGSN.

6.Taking all signaling processes into consideration, Attach can be completed within 1 to 2 minutes.2.2 Session Management Flow DelayEach GPRS terminal can be configured with one or more PDP addresses with which to process the PDP messages. Each PDP message stays in two PDP states (active and inactive) to indicate whether the data is notified. Characteristics of inactive status: The PS service notifying the specific PDP address in inactive status is unavailable. In this PDP message, there is neither routing information nor mapping information.

If the GGSN has received the PDP data packet of inactive address, it will activate it, which depends on whether the GGSN has the authority. If the activation flow cannot be activated, the GGSN will trigger the failure flow.

Start the PDP activate flow and the status changes from inactive status to active status.

Characteristics of active status:

The data packet that can reach the specific address in PDP active status is available. In this PDP message, there are routing information and mapping information.

The GPRS equipment can change from inactive status to active status.

Start the PDP activate flow and the status can be changed from inactive to active. Start the deactivate flow or change the mobility management status to idle, and the status can be changed to inactive status.Figure 23 MS Session Management Model

PDP activation delayFigure 24 Standard PDP Activation Flow

PDP activation happens after the Attach flow is complete. The establishment of the TBF needed by the transmission of the PDP activation signaling succeeds during Attach flow implementation. Therefore, PDP activation signaling is not as complicated as Attach signaling and the time needed is also shorter.

i.First the MS will report the ACTIVATE PDP CONTEXT REQUEST message and send it to the SGSN transparently through the BSC. The contents include network layer service access point identifier (NSAPI), processing identifier (TI), PDP type, access point name (APN), QoS request, and PDP Configuration Options. The delay is composed of air interface transmission time, Abis transmission time, BSC PCU processing time, and Gb interface transmission time, which is about 100 ms.

ii.The SGSN will go through the authorization and encryption process upon receiving the ACTIVATE PDP CONTEXT REQUEST message. This function is optional. Because the authorization and encryption process has been performed before the Attach flow, it is recommended to disable this function. It will save 100 ms.

iii.The SGSN sends the CREATE PDP CONTEXT REQUEST signaling to the GGSN. The signaling includes PDP type, PDP address, APN, NSAPI, mobile station ISDN (MSISDN), QoS, Selection Mode, Charging Characteristics PDP status type, and PDP Configuration Options. The delay of this process includes the transmission delay on the Gn interface and GGSN processing time. Gn is a wire transmission interface, and the GGSN processes more quickly, therefore, delay is smaller, about 10 ms.

iv.Upon receiving the CREATE PDP CONTEXT RESPONSE message, the SGSN will process the message to the ACTIVATE PDP CONTEXT ACCEPT message and send it to the MS. The message includes PDP type, PDP address, QoS, wireless priority, and PDP Configuration Options. The delay is composed of air interface transmission time, Abis transmission time, BSC PCU processing time, and GB interface transmission time, which takes about 100 ms.

v.Generally, the PDP activation delay should be within 400 ms.3 Data Flow DelayWAP webpage browsing delay

The WAP webpage browsing process includes PS Attach, PDP activation, WAP gateway connected, WAP redirection, and WAP reply. Because it belongs to data flow, the upper layer protocol contents should be paid attention to.

1.PS Attach flow and PDP activation flow: The delay in this flow has been described in the above chapters.

2.WAP gateway connected: The signaling in this process is comparatively simple (only two). The delay takes about 400 ms. But during the gateway connection, data flow of other protocols such as SSDP, NBNS, and IGMP will be triggered. The data will affect the delay, therefore, some functions on the computer should be disabled to avoid the delay brought by the data of these protocols. This process takes about 400 ms.

3.WAP redirection: When using the tool to perform the test, you should fill in the gateway address. When WAP website replies, sometimes it will feed back a new address for the MS to visit, and WAP redirection process will start. This process usually takes about 400 ms.

4.WAP reply: It includes the visit to new WAP address and the sending of the WAP webpage data. The visit process to the new WAP address includes the new WAP visit request and reply, which takes about 800 ms. The sending process of the WAP webpage data is mainly about the sending of the data in segments. The delay in this process is mainly related to the data volume (size of the webpage contents) and the size of the data segment. Generally sending a data segment takes dozens of milliseconds. Take OMCC WAP homepage visit for example, it takes about 1500 ms for the WAP page to respond.5.WAP logon success: After the downloading on the WAP webpage, the MS will confirm the WAP logon process again and request to end the session. This process lasts about dozens of milliseconds.

6.Generally, wap logon process takes less than 4 s, sometimes less than3 s.4 Introduction to Other Typical Data Service Applications4.1 FetionFetion service is a communication service of China Mobile. It integrates the communication types of voice, GPRS, and SMS, aiming to provide real-time voice service, immediate letter service, little volume communication service, and non-real-time communication service. It facilitates the communication between the Internet and mobile network.4.1.1 Fetion (Between Terminals)Figure 41 Fetion Service Flow

Fetion (between Terminals) flow:1.The terminals should activate the network access point (such as CMWAP) to access the GPRS network. Through the BTS, BSC, SGSN, GGSN, and WAP gateway, the messages can be sent to the Fetion server, that is, the integrated real-time communication service platform. For the subscribers using the SMS, the SMS center will forward the messages to the WAP gateway through the SMS gateway once receiving them.2.The Fetion server will send the messages through the GPRS network to the receiving terminal. The receiving flow is the same as the sending flow.3.The receiving terminal will return the receive success message to the Fetion server after receiving the message.4.The Fetion server will return the status report message to the sending terminal.4.1.2 Fetion (Between IM Terminals)Figure 42 Fetion Service Communication Flow

Fetion service (between IM terminals) flow:1.The terminals should activate the network access point (such as CMWAP) to access the GPRS network. Through the BTS, BSC, SGSN, GGSN, and WAP gateway, the messages can be sent to the Fetion server. For the subscribers using the SMS, the SMS center will send the messages to the WAP gateway through the SMS gateway once receiving them.2.The Fetion server will return the message to other IM terminal through the network and gateway.3.Other IM terminal will send the message to the receiving terminal through the Internet or mobile network.4.The receiving terminal will send the message to other IM terminal. The messages can be sent to the Fetion server through the gateway, and then back to the subscriber through the Internet or mobile network.4.1.3 Introduction to Fetion Service DelayAccording to Fetion service flow, much equipment is involved in Fetion service. Therefore, delay is produced in many links. From the radio network optimization perspective, the delay of Fetion service is the same with that of other services (WAP). Therefore, it can be considered that the RAN side factor has little effect on the delay of different services. Therefore, if delay of Fetion service is large, you should pay attention to the network equipment rather than the RAN side.In the following part, we use one example to describe the distribution of Fetion service delay. Limited by the testing conditions, we use one terminal to perform the Fetion login test.Terminal GPRS Attach Flow SGSN *****Delay 1.49 s*****

Terminal PDP Activation Flow GGSN *****Delay 0.51 s*****

Terminal Dialing Connection Flow WAP network gateway *****Delay 41.36 s*****We can clearly see that dialing connection flow and Fetion gateway login flow affect delay most. The two flows are mainly affected by WAP network manager and Fetion service platform equipment. Therefore, you should focus on the two flows when analyzing Fetion delay. Comparison of the two flows with GPRS attach flow and PDP activation flow shows that Fetion service delay has little to do with GSM BSS equipment. In normal conditions, delay is usually produced by the CN equipment. 4.2 MMS Service4.2.1 Introduction to MMS ServiceFigure 43 MMS Service Flow

MMS (multimedia messaging service) flow is described below:1.The terminals send the MMSs to the WAP gateway through the GPRS network. The WAP gateway finds the affiliated multimedia messaging center (MMSC) according to the MSISDN (mobile station ISDN) of the sending terminal in the DNS equipment and forwards the MMS to the MMSC of the sending terminal through the WAP gateway.2.The affiliated MMSC of the sending terminal analyzes the MSISDN of the receiving terminal, queries the affiliated MMSC in the DNS equipment, and forwards the MMS to the affiliated MMSC of the receiving terminal. The MMSC of the receiving terminal sends the PUSH message to the receiving terminal through the SMSC of the receiving terminal. If the receiving terminal does not extract the MMS within certain time, the MMSC of the receiving terminal will send the MMS to the MMS register.3.The receiving terminal will access the GPRS network after it receives the PUSH message, connect the MMSC of the receiving terminal, and extract the MMS through the WAP gateway.4.If the receiving terminal does not access the GPRS network to receive the MMS after it receives the PUSH message. The MMSC of the receiving terminal will transfer the MMS to the MMS register within certain time. If the MMS is successfully forwarded, one PUSH message will be sent to the receiving terminal.5.The receiving terminal can download the MMS through the GPRS network after it receives the PUSH message, or visit the MMS register through the Internet and extract the MMS.4.2.2 Introduction to MMS Service DelayAccording to Fetion service flow, much equipment is involved in Fetion service. Therefore, delay is produced in many links. From the radio network optimization perspective, the delay of different services is the same. Therefore, it can be considered that delay at the RAN side is the same. Therefore, if Fetion service delay is large, you should pay attention to the network equipment rather than the radio factor. Currently, the main factor that affects the MMS delay is the capacity of the MMS center.In the following part, we use one example to describe the distribution of the MMS service delay. We use one terminal to perform the receiving and sending test of the MMS. The size of the testing MMS is about 10 Kbytes.Terminal GPRS Attach Flow SGSN *****Delay 1.49s*****

Terminal PDP Activation Flow GGSN *****Delay 0.51 s*****

Terminal Dialing Connection Flow WAP network gateway *****Delay 40.19 s*****

Terminal WAP Network Gateway Connection Flow WAP network gateway *****Delay 0.73 s*****

Terminal MMS Sending Flow MMSC *****Delay 3.5 s*****

Terminal PDP Deactivation Flow GGSN *****Delay 0.5 s*****

Terminal GPRS Detach Flow SGSN *****Delay 1.49 s*****

MMSC Push Message Sending MMSC *****Delay 13.39 s*****

Terminal GPRS Attach Flow SGSN *****Delay 1.62s*****

Terminal PDP Activation Flow GGSN *****Delay 1.03 s*****

Terminal Dialing Connection Flow WAP network gateway *****Delay 41.48 s*****

Terminal WAP Network Gateway Connection WAP network gateway *****Delay 4.13 s (cell reselection affects the delay.)

Terminal MMS Receiving Flow MMSC *****Delay 1.22 s*****

Terminal PDP Deactivation Flow GGSN *****Delay 0.61 s*****

Terminal GPRS Detach Flow SGSN *****Delay 0.38 s*****We can clearly see that in Fetion service flow dialing connection flow and PUSH message delivery flow affect delay most. The two flows are mainly affected by WAP MMSC and WAP gateway equipment. Therefore, you should focus on the two flows when analyzing the MMS delay. Compared with other flows of MMS sending, the delay of MMS service has little to do with GSM BSS equipment. In normal conditions, delay is usually produced by network equipment.

VI 2011ZTE CORPORATION. All rights reserved.ZTE Confidential Proprietary

ZTE Confidential Proprietary 2011 ZTE Corporation. All rights reserved.4(2)