E-UTRAN / GERAN Interworking

Last updated: October 30, 2013

This section is only applicable to the lab application.

E-UTRAN / GERAN Interworking Overview

E-UTRAN/GERAN interworking relates to the test set working together with the Keysight E6621A PXT (See note below) to perform inter-Radio Access Technologies operations, which allows you to test the inter-RAT performance of a UE. In particular, the test set supports the following test scenarios:

Cell reselection between GERAN and E-UTRAN (bi-directional, UE-initiated only).
Network Assisted Cell Change
PS Handover between GERAN and E-UTRAN (bi-directional, network-initiated only). See External PS Handover .
Circuit Switched Fallback (CSFB) from LTE. See Unexpected Page Response in User Configurable Cell Operation Parameters .

For the hardware connection for these tests, see E-UTRAN / GERAN Interworking Physical Connection .

NOTE

E-UTRAN / GERAN interworking is restricted to using the Keysight E6621A PXT Wireless Communications Test Set as the LTE simulator. You must set up the PXT environment (cell configuration, RRC scenario, EPC, etc.) correctly so that the PXT emulates both the E-UTRAN and EPC functionalities for inter-RAT tests.

For detailed guidance on how to use the E6621A PXT, please refer to the E6621A user's guide at

http://cp.literature.keysight.com/litweb/pdf/E6621-90002.pdf

Before any E-UTRAN/GERAN inter-RAT test, you must first set up a connection between the two simulators, for signaling and packet data transferring. Namely, you must set up the E-UTRAN / GERAN Interworking Parameters and connect to the external LTE simulator successfully before performing any UE operation.

E-UTRAN / GERAN Interworking Parameters

Manual Operation: You can access the following menu from the CALL SETUP hardkey, go to the left side Call Control 4 of 4 , then press the E-UTRAN/GERAN Interworking Info ( F3 ).

E-UTRAN /GERAN Interworking Information Screen

Ext EPC IP Addr
Specifies the external EPC's IPv4 address, i.e. the IPv4 address of the LTE simulator for the test set to set up a connection via LAN.

This setting is non-volatile (it persists across partial and full presets and power-cycling the test set).

GPIB Command: SYSTem:COMMunicate:LAN:EPCore:ADDRess
Connect To External EPC
This action establishes a connection between the test set and the LTE simulator specified by Ext EPC IP Addr . When a connection is successfully set up, check the External EPC Conn Status for Connected and check the Connected EPC IP Address for the IPv4 address of the connected LTE simulator.

GPIB Command: SYSTem:COMMunicate:LAN:EPCore:CONNect
Disconnect From External EPC
When a connection is established between the test set and the LTE simulator, this action disconnects the test set from the LTE simulator specified by Ext EPC IP Addr . The External EPC Conn Status shows Not Connected if there is no connection present.

GPIB Command: SYSTem:COMMunicate:LAN:EPCore:DCONnect

Evolved Packet Core (EPC) Connection Information

External EPC Conn Status
Indicates the external EPC connection status, whether there is a connection present between the test set and the LTE simulator.

GPIB Command: SYSTem:STATus:COMMunicate:LAN:EPCore:CONNected[:STATe]?
Connected EPC IP Address
Indicates the IP address of the connected LTE simulator.

GPIB Command: SYSTem:STATus:COMMunicate:LAN:EPCore:CONNected:ADDRess?
DUT IP
Indicates the IP address(es) being used by the DUT. These addresses are allocated by EPC.

GPIB Command: SYSTem:STATus:COMMunicate:LAN:EXTernal:MS:IP:ADDRess[1]|2|3|4?

E-UTRAN / GERAN Interworking Physical Connection

The figure below shows a typical Physical connection for E-UTRAN /GERAN interworking.

Keysight PXT Test Set: working as the LTE system simulator whose functionalities and interfaces are in accordance with the standard.
Keysight 8960 Test Set: when running the E6701I lab application or above, the test set can work as a GERAN simulator.
Ethernet (LAN) Connection: interworking between the two systems relies on an ethernet connection to exchange signaling message or packet data.
Note that there are two LAN Ports on the rear panel of the test set (See Rear Panel Connectors ). For E-UTRAN /GERAN interworking, LAN 2 PORT is required to exchange signaling message or packet data. LAN 1 PORT is optional, but it is still useful for other LAN operations such as protocol logging, firmware downloads or screen captures.
RF Interface: The DUT must be able to communicate with both simulators. To accomplish this, it is common to use an RF splitter to connect the mobile to both test sets simultaneously.
GPIB Connection: GPIB connection between both test sets and a controlling PC are necessary if remote control of the instruments in the system is required.
Ethernet Switch or Hub: An ethernet switch or hub is needed in order for the Device Under Test to connect to external servers as well as for connecting the PC running WPA to the test sets.

Operating Considerations

Connecting to EPC requires the LAN 2 PORT to be configured and connected correctly. To set up the LAN 2 port on the front panel, press SYSTEM CONFIG hardkey and go toControl 1 of 2 , LAN IP Address 2 (Data+) setting is at the bottom of Instrument Setup (F1) menu.
Connecting/Disconnecting to the external EPC will cause any active PDP contexts to be deactivated.
The connection can be initiated from either the test set or the EPC simulator.
Ext EPC IP Addr must not be identical to theLAN IP Address setting. When the connection is successfully set up, Ext EPC IP Addr can not be changed.
On a full preset or format switch, the connection between the test set and the external EPC simulator will be interrupted.