User Manual

Chapter 3 - Operation and Administration of the Macro BTS NPU Configuration

4Motion 362 System Manual

3.4.12.12 Configuring PHS Rules

Packet Header Suppression (PHS) is a mechanism that conserves air-interface

bandwidth by removing parts of the packet header that remain constant along the

traffic session. PHS operates by allowing the MS and ASN-GW to associate PHS

rules to each service flow.

When PHS is enabled, a repetitive portion of the payload headers of higher layers

is suppressed in the MAC SDU by the sending entity and restored by the receiving

entity. At the uplink, the sending entity is the MS and the receiving entity is the

NPU. At the downlink, the sending entity is the NPU, and the receiving entity is

the MS. If PHS is enabled at the MAC connection, each MAC SDU is prefixed with

a PHSI, which references the Payload Header Suppression Field (PHSF).

For instance, the ASN-GW will associate a PHS rule to each provisioned service

flow intended for VoIP traffic that will suppress the IP address field from the IP

header and other unvarying fields (e.g. protocol version) from the IP and RTP

headers. The PHS rules are provisioned on a per-service profile name basis. (For

details, refer Section 3.4.12.11.4.)

PHS rules define:

 Header fields that need to be suppressed

 Static values that can be configured for the suppressed header fields

1 Enable the PHS rules configuration mode (refer to Section 3.4.12.12.1)

2 Configure the parameters for the PHS rule (refer to Section 3.4.12.12.2)

3 Terminate the PHS rules configuration mode (refer to Section 3.4.12.12.3)

You can, at any time, display configuration information (refer to

Section 3.4.12.12.5) or delete an existing PHS rules (refer to Section 3.4.12.12.4).

The following example illustrates the (sequence of) commands for enabling the

PHS rules configuration mode, configuring the parameters of a PHS rule, and then

terminating the PHS configuration mode, should be executed as shown in the

example below:

npu(config)# phs-rule phs-rule1

To configure one or more PHS rules: