In order to use the
eDRX feature, the UE requests eDRX parameters during ATTACH and TAU procedures.
Based on the configuration, the MME may accept or reject the UE’s request to
enable the eDRX feature. If the MME accepts the eDRX request, different values
of the eDRX parameters are provided based on operator policies, apart from the
parameters requested by the UE.
A new CLI command edrx is provided under
the call control profile configuration mode to configure the eDRX parameters
Paging Time Window (PTW) and eDRX cycle length duration. The operator can
either configure the option to accept the UE requested values or configure the
values using this command. If the edrx command is enabled
the MME supports eDRX feature for the UE. The UE requested values of PTW and
eDRX cycle is received in the Attach or TAU request. Under MME service
configuration mode another new edrx command is introduced which is used to configure the
H-SFN start time. The H-SFN start time is the UTC Time at which H-SFN=0 starts.
The MME calculates the paging occasion for the UE using the values of H-SFN
start time, PTW and the eDRX cycle length. The UE is paged only at the paging
occasion until the PTW expires. The MME rejects all other paging requirements
which occur in between the paging occasion.
The edrx command under the
call control profile configuration mode is also used to configure the downlink
buffer duration in DDN ACK when the MME cannot page the UE. This is an optional
configuration, a CLI keyword dl-buf-duration is provided in the eDRX command. For
Downlink Data Notifications (DDN), if the UE is not in a paging occasion, the
MME does not page the UE. The MME sends a Downlink Data Notification Reject
message to the Serving GW along with the DL buffering duration and DL suggested
packet count IEs as per the operator configuration. The packet count in DDN ACK
can be configured . An optional keyword packet-count is provided to configure the packet count
value. The MME starts a timer to page at the next paging occasion. If the
dl-buf-duration is not configured the MME rejects the DDN without these
IEs. If the
packet_count_value is not configured locally, the subscription provided
value for the
packet_count_value is used. The subscription value can be "0" in which case
packet count IE will not be sent for that subscriber even if it is configured
If the UE is not in
a paging occasion, the MME rejects the paging request for dedicated bearer
creation request and sends bearer reject to the S-GW with the cause "UE is
temporarily not reachable due to power saving". The MME starts a timer to page
at the next paging occasion. If the UE is not in a paging occasion during a MME
initiated detach where the MME needs to page the UE to send a detach request,
the MME does not page the UE and performs an implicit detach.
The following new
flags are introduced as part of this feature; these flags are supported in
GTPCv2 Indication IE:
Initiated PDN Connection Signaling Indication (PNSI): The source MME supports
sending of PNSI flag in GTPCv2 Indication IE of Context response.
for Signaling Indication (UASI): The MME supports sending of the UASI flag in
GTPCv2 Indication IE of Create Session Request and Modify Bearer Request to
indicate to the PGW that the UE is available for end to end signaling.
Connection Indication (DTCI): The MME supports receiving the DTCI flag in
Create Session Response from the SGW. The MME supports receiving of the DTCI
flag in Context Response and Forward Relocation Request from peer MME or
The MME rejects
CBR/UBR when PPF is False. The cause "UE is temporarily not reachable due to
power saving" is sent in the response by the MME if the corresponding PDN was
marked "Delay tolerant" by PGW.