How Inter-RAT Mobility performs in LTEHere I write on How Inter-RAT Mobility performs in LTE, means Handover

to LTE and Mobility from LTE.

Handover to LTE

Procedure for handover of LTE is largely the same as the handover

procedure in LTE. The main difference is that the handover to LTE AS a

whole-configuration must be signaled, and the LTE it is possible to use ‘

signaling delta “, according to which only the changes in the configuration

are displayed.

If you like to offer subscribers a better handover had not yet been activated

in previous INSTALLMENTS, E-UTRAN activates Ciphering, possibly using

the NULL algorithm, as part of the procedure. E-UTRAN also establishes

SRB1, SRB2 and one or more of the DRBs (i.e. at least DRB is associated

with the default “bearer of EPS).

Mobility from LTE

Generally, the procedure for LTE mobility from another RAT supports both

handover and Cell Change Order (CCO), possibly with Assistance Network

(NACC – Network Assisted Cell Change). The procedure CCO / NACC is

applicable only to GERAN mobility.

Mobility from LTE is performed only after security has been activated.

When used for enhanced CSFB18 for CDMA2000, the handover procedure

includes support for parallel (i.e. both 1XRTT and HRPD), surrendered to

1XRTT along with redirection to HRPD, and redirection to HRPD only.

The procedure is shown in Figure.

1. The UE may send a Measurement Report message.

2. In the case of handover (unlike CCO), the source eNodeB requests the

target radio access (RAN) node to prepare for handover. As part of the

source of “the handover of preparing the query” eNodeB provides

information on applicable between RAT UE capabilities, as well as

information about the current set-carriers. In response to the target RAN

generates a ‘handover command, and returns the source eNodeB.

3. Source eNodeB sends a message from the mobile team to EUTRA UE,

which includes inter-RAT or message received from the target (in the case

of transmission), or the target cell / frequency and inter-RAT several

parameters (in the case of COC).

4. After receiving the message from the mobility team EUTRA, UE starts

timer T304 and connect to the target node, or by using the radio to get the

configuration (transfer) or by initiating a connection (CBS) in accordance

with the specifications of the target RAT.

The upper layers of the UE reports to the AS the target RAT, that the

carriers are installed. Consequently, UE may occur if some of the

established carriers, were not admitted to the target RAN node.

For CDMA2000

For CDMA2000, additional procedures have been defined to support the

transfer of information dedicated to the CDMA2000 upper layers, which are

used to record the presence of the UE in the core network before

performing the handover target (the preregistration). These procedures use

SRB1