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RAN Feature Description Table of Contents Table of Contents Chapter 16 PDCP Header Compression..................................16-1 16.1 Introduction................................................16-1 16.1.1 Definition............................................16-1 16.1.2 Purposes..............................................16-1 16.1.3 Terms and Abbreviations...............................16-2 16.2 Availability................................................16-5 16.2.1 Network Elements Involved.............................16-5 16.2.2 Software Releases.....................................16-5 16.2.3 Miscellaneous.........................................16-5 16.3 Impact......................................................16-6 16.3.1 On System Performance.................................16-6 16.3.2 On Other Features.....................................16-6 16.4 Technical Description.......................................16-6 16.4.1 PDCP Header Compression Configuration Model...........16-6 16.4.2 Overview of Header Compression........................16-6 16.4.3 System Architecture...................................16-7 16.4.4 Process for Header Compression.......................16-10 16.4.5 Implementation of PDCP Header Compression by Huawei RNC 16- 16 16.5 Capabilities...............................................16-18 16.6 Implementation.............................................16-18 16.6.1 Enabling PDCP Header Compression.....................16-18 16.6.2 Reconfiguring PDCP Header Compression Parameters.....16-19 16.6.3 Disabling PDCP Header Compression....................16-20 16.7 Maintenance Information....................................16-20 16.7.1 Alarms...............................................16-20 16.7.2 Counters.............................................16-20 16.8 References.................................................16-22 Huawei Technologies Proprietary i

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Page 1: 16-PDCP Header Compression

RAN Feature Description Table of Contents

Table of Contents

Chapter 16 PDCP Header Compression..................................................................................16-116.1 Introduction..................................................................................................................16-1

16.1.1 Definition...........................................................................................................16-116.1.2 Purposes...........................................................................................................16-116.1.3 Terms and Abbreviations...................................................................................16-2

16.2 Availability....................................................................................................................16-516.2.1 Network Elements Involved...............................................................................16-516.2.2 Software Releases............................................................................................16-516.2.3 Miscellaneous....................................................................................................16-5

16.3 Impact..........................................................................................................................16-616.3.1 On System Performance...................................................................................16-616.3.2 On Other Features.............................................................................................16-6

16.4 Technical Description...................................................................................................16-616.4.1 PDCP Header Compression Configuration Model.............................................16-616.4.2 Overview of Header Compression.....................................................................16-616.4.3 System Architecture..........................................................................................16-716.4.4 Process for Header Compression....................................................................16-1016.4.5 Implementation of PDCP Header Compression by Huawei RNC....................16-16

16.5 Capabilities................................................................................................................16-1816.6 Implementation..........................................................................................................16-18

16.6.1 Enabling PDCP Header Compression.............................................................16-1816.6.2 Reconfiguring PDCP Header Compression Parameters.................................16-1916.6.3 Disabling PDCP Header Compression............................................................16-20

16.7 Maintenance Information............................................................................................16-2016.7.1 Alarms.............................................................................................................16-2016.7.2 Counters..........................................................................................................16-20

16.8 References................................................................................................................. 16-22

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RAN Feature Description List of Figures

List of Figures

Figure 16-1 PDCP Header Compression configuration model............................................16-6

Figure 16-2 Block diagram of header compression.............................................................16-7

Figure 16-3 UMTS structure for the PS domain..................................................................16-8

Figure 16-4 User plane of the protocol stack for the PS domain.........................................16-9

Figure 16-5 PDCP structure in the radio interface protocol architecture.............................16-9

Figure 16-6 Process for header compression...................................................................16-10

Figure 16-7 Exponentially increasing period after a change.............................................16-14

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RAN Feature Description List of Tables

List of Tables

Table 16-1 NEs required for PDCP header compression....................................................16-5

Table 16-2 RAN products and related versions...................................................................16-5

Table 16-3 PDCP header compression counters...............................................................16-21

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RAN Feature Description Chapter 16 PDCP Header Compression

Chapter 16 PDCP Header Compression

16.1 Introduction

16.1.1 Definition

The Packet Data Convergence Protocol (PCDP) is an important component of the protocols of the radio interface L2. It provides the following functions:

Transfer of packet data Header compression and decompression of IP data streams Lossless SRNS relocation Traffic measurement

The general process of PDCP header compression is as follows:

1) The redundant protocol headers are compressed before being transmitted on a link.

2) The packets are decompressed to their original status when they are received at the other end of the link.

16.1.2 Purposes

PDCP header compression is applied for the following purposes.

I. Reducing Header Overhead

The common size of a TCP segment in bulk transfer over a medium speed link is 512 bytes. When a TCP segment is tunneled, the size of an IPv4, IPv6, or TCP header is 100 bytes. Thus, IPv6 and TCP headers account for 19.5% of the whole size, and IPv4 and TCP headers account for 11.7%. After PDCP header compression, however, the headers only account for less than 1% of the whole size. PDCP header compression greatly reduces header overhead.

In addition, for speech services, a packet with huge amount of data comes with significant delay. Small packets must be the first choice for short end-to-end delay. For this purpose, the header overhead can be reduced to a large extent by PDCP header compression.

II. Shortening Response Time

When a large header is transmitted over a low speed link, echoing of characters takes more than 100–200 ms, which is the maximum tolerable time for people not to feel that the system is sluggish.

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PDCP header compression shortens response time and improves the echoing rate of characters.

III. Reducing Packet Loss Rate

After PDCP header compression, fewer bits are transmitted for each packet. Therefore, the packet loss rate is lower for a given Bit Error Rate (BER).

16.1.3 Terms and Abbreviations

I. Terms

Term Description

SubheaderAn IPv6 base header, an IPv6 extension header, an IPv4 header, a UDP header, or a TCP header.

Subheader chain

A chain of subheaders.

Compress

The act of reducing the size of a header by removing header fields or reducing the size of header fields.This is done in such a way that a decompressor can re-form the header if its context state is identical to the context state used in compression of the header.

Decompress The act of restoring the original header.

Context identifier (CID)

A small unique number that identifies the context used to decompress a compressed header.CIDs are carried in full headers or compressed headers.

Context

A bit string that the compressor uses to compress a header and the decompressor uses to decompress a header.It is the uncompressed version of the last header that the compressor sends or the decompressor receives over the link. The context for a packet stream is associated with a CID. In addition, the context for a non-TCP packet stream is associated with a generation.

Generation

A number that is incremented whenever the context with a specified CID changes.A generation is specific for a non-TCP packet stream and carried by a full or compressed non-TCP header. Each new version of the context with a specified CID is associated with a generation.

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Term Description

Packet streamA sequence of packets that have similar headers and share a context.

Full header

An uncompressed header that updates or refreshes the context for a packet stream.It carries a CID. For a non-TCP packet stream, a full header also carries a generation.

Regular header

An uncompressed header that carries neither a CID nor a generation.

Incorrect decompression

A situation where a decompressed header is different from the header before compression.Usually, incorrect decompression is due to context mismatch between the compressor and decompressor or due to bit errors during transmission of the compressed header.

Differential coding

A compression technique where the compressed value of a header field is the difference between the current value of the field and the value of the same field in the previous header in the same packet stream.By differential coding, the decompressor obtains the value of the field by adding the value in the compressed header to its context.

Multi-hopData are forwarded by multiple uncertain routers before reaching the destination.

II. Abbreviations

Abbreviation Full Spelling

ARPU Average Revenue Per User

BER Bit Error Rate

CN Core Network

FTP File Transfer Protocol

HC Header Compression

GGSN Gateway GPRS Support Node

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Abbreviation Full Spelling

GPRS General Packet Radio Service

GSM Global System for Mobile communications

GTP-U GPRS Tunneling Protocol for User Plane

IP Internet Protocol

IPv4 Internet Protocol version 4

IPv6 Internet Protocol version 6

MTU Maximum Transfer Unit

PDCP Packet Data Convergence Protocol

QoS Quality of Service

RAB Radio Access Bearer

RB Radio Bearer

RFC Request For Comments

RLC Radio Link Control

RNC Radio Network Controller

RTP Real-Time Transport Protocol

RTT Round Trip Time

SAP Service Access Point

SDU Service Data Unit

SGSN Serving GPRS Support Node

TCP Transmission Control Protocol

UDP User Datagram Protocol

UE User Equipment

UTRAN UMTS Terrestrial Radio Access Network

WCDMA Wideband Code Division Multiple Access

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16.2 Availability

16.2.1 Network Elements Involved

Table 16-1 describes the NEs involved with PDCP header compression.

Table 16-1 NEs required for PDCP header compression

UE NodeB RNCMSC

ServerMGW SGSN GGSN HLR

√ – √ – – – – –

Note:

–: not required

√: required

Note:

This chapter describes only the availability of the UE and the RNC.

16.2.2 Software Releases

Table 16-2 describes the versions of RAN products that support PDCP header compression.

Table 16-2 RAN products and related versions

Product Version Remark

RNC BSC6800

V100R002 and later releases

Support IPv4 header compression

V100R006 and later releases

Support IPv4 and IPv6 header compressions

16.2.3 Miscellaneous

PDCP header compression is an optional feature of Huawei UMTS RAN. The corresponding license must be bought to enable the feature.

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16.3 Impact

16.3.1 On System Performance

None.

16.3.2 On Other Features

None.

16.4 Technical Description

16.4.1 PDCP Header Compression Configuration Model

The configuration model for PDCP Header Compression is as show in Figure 16-2.

Max CID value for TCP connections

Max CID value for non-TCP connections

Max number of compressed non-TCP headers

Max time for sending compressed headers[s]

RFC2507 default parameter switch

Max control header size[byte]

FRC.Class

RNC

RadioClass

GlobalParaClass

Channel class algorithm switch

CORRMALGOSWITCH.Class

Figure 16-2 PDCP Header Compression configuration model

16.4.2 Overview of Header Compression

The IP protocol, transport protocols like TCP or UDP, and optional application protocols are described in the header of a packet. Data in a header serves long-distance transport over multiple links or multi-hop network. The header includes the following data:

Source IP address Destination IP address

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Port information Protocol ID Sequence number Error checking information

For TCP packets in telecommunications, many fields are constant and others change with small and predictable values. Depending on whether the fields remain constant or change in specific patterns, some fields can be either excluded from each packet or represented in a smaller number of bits. This is described as header compression.

Header compression uses the concept of packet stream context. A context is a set of data about field values and value change patterns in the packet header. For each packet stream, the context is formed at the compressor and the decompressor. After the context is established on both sides, the compressor can compress the packets.

Figure 16-3 shows the block diagram of header compression.

Context

Headercompression

Headerdecompression

Context

Packet stream

Packet stream inforward direction

Compressed packets

Feedback

Figure 16-3 Block diagram of header compression

To initiate compression of the headers of a packet stream, a full header carrying a CID is transmitted over the link. The compressor and decompressor store most fields of this full header as the context. The context contains the fields of the headers whose values are constant. Thus, these fields need not be sent over the link at all, or only change little between consecutive headers. Then, only a few bits are required to send the difference from the previous value, instead of sending the absolute value.

Any change in fields that are expected to be constant in a packet stream will cause the compressor to send a full header again to update the context at the decompressor. If the contexts are the same at the compressor and the decompressor, headers can be decompressed to the original ones. Thus, a header compression scheme provides mechanisms to update the context at the decompressor and to detect or avoid incorrect decompression.

16.4.3 System Architecture

I. UMTS Structure for the PS Domain

Figure 16-4 shows the UMTS structure for the Packet Switched (PS) domain.

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The header compression function is provided by the RNC. Packet data is transferred from the Internet or other external networks to the RNC by the GGSN and SGSN through the GPRS Tunnel Protocol (GTP). The RNC relays the packet data to the UE.

Uu lu

Cu

lub

ExternalnetworksCNUTRANUE

USIM

ME

NodeB

NodeBRNC SGSN

VLR

HLR

GGSN Internet

Figure 16-4 UMTS structure for the PS domain

II. User Plane of the Protocol Stack for the PS Domain

As shown in Figure 16-1, the user plane has a layered protocol structure. It transfers user data through data transfer control procedures. Header compression is performed by PDCP.

After receiving data from the PS domain through the GTP-U tunnel, the RNC processes the data as follows:

3) Performs header compression.4) Sends the compressed data to the RLC module on the lower layer.5) Further processes the data on lower layers and then sends the data to the UE

through the Uu interface.

After receiving the data, the UE processes the data as follows:

1) Processes the data on the lower layers.2) Sends the data to the PDCP sub layer and decompresses it.3) Sends the data to the application layer.

That is the process of downlink data transfer. The uplink data transfer is of the same principle.

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L1

RLC

PDCP

MAC

E.g., IP,PPP

Appli-cation

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

3G SGSNUTRANUEIu-PSUu Gn Gi

3G GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

E.g., IP,PPP

Figure 16-1 User plane of the protocol stack for the PS domain

III. PDCP Structure in the Radio Interface Protocol Architecture

Figure 16-2 shows the PDCP structure in the radio interface protocol architecture.

. . .

. . .

RLC

PDCP-SDU

PDCP sublayer

RLC-SDU

Radio bearers

HC protocoltype 1

HC protocoltype 2

PDCP entity

HC protocoltype 1

HC protocoltype 2

PDCP entity

SDUnumbering

HC protocoltype 1

PDCP entity

UM-SAP AM-SAP TM-SAP

C-SAP

PDCP-SAPs

Figure 16-2 PDCP structure in the radio interface protocol architecture

The PDCP sub layer contains many PDCP entities.

Every PS domain Radio Access Bearer (RAB) is associated with one Radio Bearer (RB), which in turn is associated with one PDCP entity. Each PDCP entity is

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associated with one or two (one for each direction) RLC entities, depending on the RB characteristic (namely, unidirectional or bidirectional) and RLC mode.

PDCP in the RNC and UE performs header compression on IP data streams at the transmitting entity, and header decompression at the receiving entity. The headers include TCP/IP and RTP/UDP/IP ones for IPv4 and IPv6. Every PDCP entity uses zero, one, or several different header compression protocol types.

16.4.4 Process for Header Compression

Figure 16-3 shows the process for header compression.

OutputInput

Compressor

Decompressor

Compressible chainof header judgment

algorithm

Packet streamjudgment algorithm

Packetstream type

Non-TCP

Slow-start algorithm

Periodic headerrefresh algorithm

TCP

Feedback

No

No

Header requestalgorithm

Twice algorithm

Decompressionfails?

Yes

Decompressionfails again?

Yes

Figure 16-3 Process for header compression

The process involves the following algorithms:

Compressible Chain of Subheader Judgment Algorithm Packet Stream Judgment Algorithm

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Twice Algorithm for TCP Packet Streams Header Request Algorithm for TCP Packet Streams Compression Slow-Start Algorithm for Non-TCP Packet Streams Periodic Header Refresh Algorithm for Non-TCP Packet Streams

I. Compressible Chain of Subheader Judgment Algorithm

A compressible subheader can be one of the following:

An IPv6 base header An IPv6 extension header A TCP header A UDP header An IPv4 header

The compressible chain of subheaders extends from the beginning of the header. It includes the following two types:

A chain beginning from but not including the first header that is not an IPv4 header, an IPv6 base or extension header, a TCP header, or a UDP header

A chain beginning from and including the first TCP header, UDP header, fragment header, Encapsulating Security Payload (ESP) header, or IPv4 header for a fragment

Both types fit a chain of subheaders that contain a fragment header and ends at a tunneled IPX packet. Since the second type gives a shorter chain, the compressible chain of subheaders stops at the fragment header.

An implementation MUST NOT compress more than the initial MAX_HEADER (Max control header size [byte]) bytes of a header. An implementation MUST NOT partially compress a subheader. Thus, the part of the header that is stored as context and is compressed is the longest initial sequence of entire subheaders that is not larger than MAX_HEADER (Max control header size [byte]) bytes.

Parameter:

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Parameter Name Max control header size[byte]

Parameter ID MAXHEADER

GUI Range 60–65535

Physical Range& Unit byte

Default Value 168

Optional/Mandatory Optional

MML Command SET FRC

Description:

As a PDCP specified parameter, it indicates the maximum control header size in bytes that may be compressed.

Configuration Rule and Restriction:

MAXHEADER (Max control header size [byte]) is configurable only if RFC2507DEFPARASWITCH (RFC2507 default parameter switch) is enabled.

I. Packet Stream Judgment Algorithm

The compressor uses the criterion that it finds appropriate to group packets into packet streams. To determine which packet stream a packet belongs to, a compressor performs the following:

6) Checks the compressible chain of subheaders.7) Checks the contents of an upper layer protocol header, such as TCP or UDP.8) Checks if the defining fields of compressible chain of subheaders are changed.

If too many fields are used for identification, performance might suffer because more CIDs will be used and the wrong CIDs might be reused when new flows need CIDs. If too few fields are used for identification, performance might suffer because there are too frequent changes to the context.

The CID spaces for TCP and non-TCP are separate. Therefore, a TCP CID and a non-TCP CID never identify the same context even if they have the same value. When the same number of bits is used for the CIDs, it only doubles the available CID space. The maximum CID value configured for TCP is called TCPSPACE (Max CID value for TCP connections). The maximum CID value configured for non-TCP is called NONTCPSPACE (Max CID value for non-TCP connections).

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Parameter:

Parameter Name Max CID value for TCP connections

Parameter ID TCPSPACE

GUI Range 3–255

Physical Range& Unit None

Default Value 15

Optional/Mandatory Optional

MML Command SET FRC

Description:

As a PDCP specified parameter, it indicates the maximum CID value used for TCP connections.

Parameter Name Max CID value for non-TCP connections

Parameter ID NONTCPSPACE

GUI Range 3–65535

Physical Range& Unit None

Default Value 15

Optional/Mandatory Optional

MML Command SET FRC

Description:

As a PDCP specified parameter, it indicates the maximum CID used for non-TCP connections.

Configuration Rule and Restriction:

TCPSPACE (Max CID value for TCP connections) is configurable only if RFC2507DEFPARASWITCH (RFC2507 default parameter switch) is enabled.

NONTCPSPACE (Max CID value for non-TCP connections) is configurable only if RFC2507DEFPARASWITCH (RFC2507 default parameter switch) is enabled.

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II. Twice Algorithm for TCP Packet Streams

In this algorithm, the decompressor computes a checksum to check if its context has been updated properly. If the checksum fails, the error might be caused by a lost segment that did not update the context properly. If the lost segment contained the same delta as the current, the delta of the current segment is then added to the context again. The decompressor recomputes the checksum and, if successful, continues to deliver packets. If the repair fails, the delta is applied again, that is, adding the delta and recomputing the checksum.

Analysis of traces of diverse TCP bulk transfers shows that applying the delta of the current segment one or two times repairs the context for 83% to 99% of all single-segment losses in the data stream. For the acknowledgment stream, the success rate is lower due to the delayed acknowledgment mechanism of TCP. The Twice mechanism repairs the context for 53% to 99% of the losses in the acknowledgment stream.

III. Header Request Algorithm for TCP Packet Streams

After the Twice algorithm fails, another recovery mechanism, called Header Request, is available for repairing the context at the decompressor. When failing to repair the context after a loss, the decompressor requests a complete header from the compressor. This is possible only when bidirectional links are used, because the decompressor must communicate with its compressor. The decompressor sends a context state message to the compressor when making a header request. The context state message can include all compressed packet streams that need a context update.

IV. Compression Slow-Start Algorithm for Non-TCP Packet Streams

To help the decompressor recover quickly from loss of a full header that has changed the context, full headers are sent periodically with an exponentially increasing period after a change in the context, as shown in Figure 16-1. This technique avoids an exchange of messages between the compressor and decompressor. Such exchanges are costly for wireless mobiles, because more power is consumed by the transmitter and delay can be introduced by switching between transmission and reception.

| . | . ...| . . . . | . . . . . . . . |. . . . . . . . . . . . . . . . | ..............................

| : full header. : compressed header

Figure 16-1 Exponentially increasing period after a change

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Figure 16-1 shows how packets are sent after a change in the context. The compressor keeps a variable F_PERIOD for each non-TCP packet stream. The variable keeps track of how many compressed headers are sent between full headers. When the headers of a non-TCP packet stream change so that its context changes, a full header is sent and F_PERIOD is set to 1. After F_PERIOD compressed headers are sent, a full header is sent. F_PERIOD is doubled each time a full header is sent during compression slow-start.

V. Periodic Header Refresh Algorithm for Non-TCP Packet Streams

To avoid losing too many packets when a receiver loses its context, there is an upper limit, F_MAX_PERIOD (Max number of compressed non-TCP headers), on the number of compressed headers in a non-TCP packets stream. These compressed headers might be sent between header refreshes. If a packet is to be sent and F_MAX_PERIOD (Max number of compressed non-TCP headers) compressed headers have been sent after the last full header was sent for this packet stream, a full header must be sent.

To avoid long periods of disconnection for low data rate packet streams, there is also an upper limit, F_MAX_TIME (Max time for sending compressed headers[s]), on the time between full headers in a non-TCP packet stream. If a packet is to be sent and more than F_MAX_TIME (Max time for sending compressed headers[s]) seconds have passed after the last full header was sent for this packet stream, a full header must be sent.

Parameter:

Parameter Name Max number of compressed non-TCP headers

Parameter ID F_MAX_PERIOD

GUI Range 1–65535

Physical Range& Unit None

Default Value 256

Optional/Mandatory Optional

MML Command SET FRC

Description:

As a parameter specified in PDCP, it indicates the maximum number of compressed non-TCP headers that may be sent without a full header. The word "compressed" means some unnecessary header information is not transmitted with the packet data so as to save network resource.

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Parameter Name Max time for sending compressed headers[s]

Parameter ID F_MAX_TIME

GUI Range 1–255

Physical Range& Unit s

Default Value 5

Optional/Mandatory Optional

MML Command SET FRC

Description:

As a PDCP specified parameter, it indicates the maximum duration for sending compressed headers after the last full header is sent.

Configuration Rule and Restriction:

F_MAX_PERIOD (Max number of compressed non-TCP headers) is configurable only if RFC2507DEFPARASWITCH (RFC2507 default parameter switch) is enabled.

F_MAX_TIME (Max time for sending compressed headers[s]) is configurable only if RFC2507DEFPARASWITCH (RFC2507 default parameter switch) is enabled.

16.4.5 Implementation of PDCP Header Compression by Huawei RNC

I. Overview

The implementation of PDCP header compression by Huawei RNC completely complies with the IP Header Compression (IPHC) protocol RFC2507.

II. Parameters Configured for the Implementation by Huawei

FRC_PDCP_COMPRESS_SWITCH (Channel class algorithm switch)

When it is checked and the PDCP header compression license is enabled, the PDCP header compression algorithm will be applied in the RNC.

PDCP_IPV6_HEAD_COMPRESS_SWITCH (Channel class algorithm switch)

When it is checked and the PDCP header compression function is enabled, the PDCP header compression algorithm for IPv6 will be applied in the RNC.

RFC2507DEFPARASWITCH (RFC2507 default parameter switch)

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It is the default parameter switch of RFC2507.

Parameter:

Parameter Name Channel class algorithm switch

Parameter IDCHSWITCH:

FRC_PDCP_COMPRESS_SWITCH

GUI Range 0–1

Physical Range& Unit None

Default Value 0

Optional/Mandatory Optional

MML Command SET CORRMALGOSWITCH

Description:

When it is checked and the PDCP header compression license is enabled, the PDCP header compression algorithm will be applied in the RNC.

Parameter Name Channel class algorithm switch

Parameter IDCHSWITCH:

PDCP_IPV6_HEAD_COMPRESS_SWITCH

GUI Range 0–1

Physical Range& Unit None

Default Value 0

Optional/Mandatory Optional

MML Command SET CORRMALGOSWITCH

Description:

When it is checked and the PDCP header compression function is enabled, the PDCP header compression algorithm for IPv6 will be applied in the RNC.

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Parameter Name RFC2507 default parameter switch

Parameter ID RFC2507DEFPARASWITCH

GUI Range DISABLE, ENABLE

Physical Range& Unit None

Default Value ENABLE

Optional/Mandatory Optional

MML Command SET FRC

Description:

RFC2507 default parameter switch

16.5 CapabilitiesNone.

16.6 Implementation

16.6.1 Enabling PDCP Header Compression

I. Hardware Installation

This feature does not need extra hardware.

II. License Update

To activate the license for PDCP header compression, perform the following steps:

9) Get the new license.10) Download the license to the BAM installation directory\FTP\license through FTP.11) Execute the ACT LICENSE command on the M2000 or the RNC LMT to activate

the new license.

III. Data Configuration

To configure the parameters for the PDCP header compression, perform the following steps:

12) Execute the SET CORRMALGOSWITCH command to enable the following switches: FRC_PDCP_COMPRESS_SWITCH PDCP_IPV6_HEAD_COMPRESS_SWITCH

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13) Execute the SET FRC command to enable the switch RFC2507DEFPARASWITCH and configure the following parameters: FMAXPERIOD FMAXTIME MAXHEADER TCPSPACE NONTCPSPACE

IV. Verification of the Enabled Feature

Execute the LST CORRMALGOSWITCH or the LST FRC command to check if the activation succeeds.

V. Examples

// Enable the FRC_PDCP_COMPRESS_SWITCH and the

PDCP_IPV6_HEAD_COMPRESS_SWITCH.

SET CORRMALGOSWITCH: ChSwitch=FRC_PDCP_COMPRESS_SWITCH-

1&PDCP_IPV6_HEAD_COMPRESS_SWITCH-1;

// Verify the feature activation.

LST CORRMALGOSWITCH: LstFormat=VERTICAL;

// The result indicates that the activation succeeds.

// Enable the RFC2507DEFPARASWITCH and configure relevant parameters.

SET FRC: Rfc2507DefParaSwitch=ENABLE, FMaxPeriod=256, FMaxTime=5,

MaxHeader=168, TcpSpace=15, NonTcpSpace=15;;

// Verify the feature activation.

LST FRC: LstFormat=VERTICAL;

// The result indicates that the activation succeeds.

16.6.2 Reconfiguring PDCP Header Compression Parameters

I. Switch Adjustment

Execute the SET CORRMALGOSWITCH command to adjust the following switches:

FRC_PDCP_COMPRESS_SWITCH PDCP_IPV6_HEAD_COMPRESS_SWITCH

Execute the SET FRC command to adjust the switch RFC2507DEFPARASWITCH.

II. Parameter Reconfiguration Verification

Execute the LST CORRMALGOSWITCH or the LST FRC command to check if the reconfiguration succeeds.

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III. Examples

// Disable the PDCP_IPV6_HEAD_COMPRESS_SWITCH.

SET CORRMALGOSWITCH: PDCP_IPV6_HEAD_COMPRESS_SWITCH-0;

// Verify the reconfiguration.

LST CORRMALGOSWITCH: LstFormat=VERTICAL;

// The result indicates that the reconfiguration succeeds.

// Disable the RFC2507DEFPARASWITCH.

SET FRC: RFC2507DEFPARASWITCH=DISABLE;

// Verify the reconfiguration.

LST FRC: LstFormat=VERTICAL;

// The result indicates that the reconfiguration succeeds.

16.6.3 Disabling PDCP Header Compression

I. Switch Disabling

Execute the SET CORRMALGOSWITCH or the SET FRC to disable the switches.

II. Verification of the Disabled Feature

Execute the LST CORRMALGOSWITCH or the LST FRC to check if the deactivation succeeds.

III. Examples

// Disable the FRC_PDCP_COMPRESS_SWITCH and the

PDCP_IPV6_HEAD_COMPRESS_SWITCH

SET CORRMALGOSWITCH: ChSwitch=FRC_PDCP_COMPRESS_SWITCH-

0&PDCP_IPV6_HEAD_COMPRESS_SWITCH-0;

// Verify the deactivation.

LST CORRMALGOSWITCH: LstFormat=VERTICAL;

// The result indicates that the deactivation succeeds.

16.7 Maintenance Information

16.7.1 Alarms

None.

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16.7.2 Counters

The related counters belong to RNC -> RNC PDCPGTPU, where RNC refers to the measurement type, and RNC PDCPGTPU refers to the measurement unit. Table 16-1 describes the counters.

Table 16-1 PDCP header compression counters

Counter Description

VS.PDCP.DL.IPV4 Number of IPV4 PDCP instances on DL

VS.PDCP.UL.IPV4 Number of IPV4 PDCP instances on UL

VS.PDCP.DL.IPV6 Number of IPV6 PDCP instances on DL

VS.PDCP.UL.IPV6 Number of IPV6 PDCP instances on UL

VS.PDCP.DL.PPP Number of PPP PDCP instances on DL

VS.PDCP.UL.PPP Number of PPP PDCP instances on UL

VS.PDCP.DL.2507.TCP Number of DL data flows with TCP contexts

VS.PDCP.DL.2507.OtherNumber of DL data flows with NONTCP Contexts

VS.PDCP.DL.NoCompress Number of DL packets not compressed

VS.PDCP.UL.DecompressError Number of UL packets with error in extraction

VS.PDCP.DL.PktSize.Mean Average size of DL packets

VS.PDCP.UL.PktSize.Mean Average size of UL packets

VS.PDCP.DL.PktHeader.Mean Average size of DL packet headers

VS.PDCP.UL.PktHeader.Mean Average size of UL packet headers

VS.GTP.DL.PktDist.1.200 Number of DL packets with 0–200 bytes

VS.GTP.DL.PktDist.201.500 Number of DL packets with 201–500 bytes

VS.GTP.DL.PktDist.501.1000 Number of DL packets with 501–1000 bytes

VS.GTP.DL.PktDist.1001.MaxNumber of DL packets with 1001 bytes and above

VS.GTP.UL.PktDist.1.200 Number of UL packets with 0–200 bytes

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Counter Description

VS.GTP.UL.PktDist.201.500 Number of UL packets with 201–500 bytes

VS.GTP.UL.PktDist.501.1000 Number of UL packets with 501–1000 bytes

VS.GTP.UL.PktDist.1001.MaxNumber of UL packets with 1001 bytes and above

VS.PDCP.DL.HdrCompressRatio Compression ratio of DL packet headers

VS.PDCP.DL.PktCompressRatio Compression ratio of DL packets

16.8 References RFC2507 IP Header Compression 3GPP TS 25.323 V5.2.0 (2002-09) "Packet Data Convergence Protocol (PDCP)

Specification"

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