A Hyper-SFN (H-SFN) frame structure is defined for regular idle mode DRX. Each H-SFN value corresponds to a legacy SFN cycle comprised of 1024 radio frames (10.24 seconds). The eDRX consists of values that are a power of 2, ranging from 5.12 seconds (that is, 5.12, 10.24, 20.48 seconds and so on) up to a maximum of 2621.44 seconds (43.69 minutes). When EDRX is enabled for a UE, the UE is reachable for paging in specific Paging Hyperframes (PH), which is a specific set of H-SFN values. The PH computation is a formula that is function of the EDRX cycle, and a UE specific identifier. This value can be computed at all UEs and MMEs without need for signalling. The MME includes the extended idle mode DRX cycle length in paging message to assist the eNodeB in paging the UE.

The MME also assigns a Paging Time Window length, and provides this value to the UE during attach/TAU procedures together with the extended idle mode DRX cycle length. The UE first paging occasion is within the Paging Hyperframe. The UE is assumed reachable for paging for an additional Paging Time Window length after first paging occasion. After the Paging Time Window length, the MME considers the UE unreachable for paging until the next Paging Hyperframe.

In order for the UE to be paged at similar time, the H-SFN of all eNodeBs and MMEs must be loosely synchronized. Each eNodeB and MME synchronizes the H-SFN counter so that the start of H-SFN=0 coincides with a pre-configured time. It is assumed that eNodeBs and MMEs are able to use the same H-SFN value with accuracy in the order of legacy DRX cycle lengths, for example 1 to 2 seconds. There is no need for synchronization at SFN level. There is no signaling between network nodes required to achieve this level of loose H-SFN synchronization.

When the MME receives trigger for paging and the UE is reachable for paging, the MME sends the paging request. If the UE is not reachable for paging, then the MME pages the UE just before the next paging occasion. The MME determines the Paging Time Window length based on paging retransmission strategy, and uses it to execute the retransmission scheme.

The MME uses the T3413 timer for non-eDRX UEs to re-transmit paging. For eDRX UEs the MME uses the T3415 timer and on expiry of T3415 timer, the network aborts the paging procedure.

If a session recovery occurs then the eDRX timer re-starts only for the remaining time of the total time configured before session recovery. This is to ensure that the UE and MME are in sync with respect to the paging occasion.

The eDRX feature is compatible only with IoT devices. It is not available for all Mobile Stations (MS), that is, only those MSs and their respective Base Service Stations (BSS) that have the extended coverage parameters are supported by the SGSN.

The eDRX feature complies with the following standards:

• 3GPP TS 23.682 version 13.4.0, Architecture enhancements to facilitate communications with packet data networks and applications (Release 13)

• 3GPP TS 24.302 version 13.5.0, Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 (Release 13)

• 3GPP TS 23.401 version 13.5.0, General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access.

• 3GPP TS 29.274 version 13.5.0, 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunneling Protocol for Control plane (GTPv2-C); Stage 3

• 3GPP TS 36.304 version 13.3.0 , Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) procedures in idle mode

• 3GPP TS 36.300 version 13.2.0 , Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2

• 3GPP TS 36.413 version 13.1.0, Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP)

• 3GPP TS 24.008 version 13.5.0, Mobile radio interface Layer 3 specification; Core network protocols; Stage 3

configure
   call-control-profileprofile_name
      edrx { ue-requested | ptw ptw_value edrx-cycle cycle_length_value [ dl-buf-duration [ packet-count packet_count_value ] ] }
      remove edrx
      end

Notes:

• The remove keyword disables the eDRX configuration on the MME.

• The edrx keyword configures extended discontinuous reception parameters.

• The ue-requested keyword specifies the accepted UE requested values of the of the Paging Time Window (PTW) and the eDRX cycle length received from the UE in the Attach Request/TAU Request message be accepted.

• The ptw ptw_value keyword is used to configure the PTW value as an integer ranging from 0 to 20 seconds.

  In 21.2 and later releases: The PTW value can be configured as an integer ranging from 0 to 15 seconds.

• The edrx-cycle keyword is used to configure the eDRX cycle length. The cycle_length_value is an integer value from 512 to 262144. It is a multiple of 2 starting from 512 up to 262144 (for example: 512, 1024, 2048, and so on).

• The dl-buf-duration keyword sends Downlink Buffer Duration data in the DDN ACK message when MME is unable to page the UE.

• The packet-count keyword is used to send "DL Buffering Suggested Packet Count" in DDN ACK when unable to page UE. The packet_count_value is an integer value from 0 to 65535. 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 the packet count IE will not be sent for that subscriber even if it is configured locally.

• This command is disabled by default.

Verifying eDRX on the MME

Execute the show call-control-profile full name profile_name command to verify the configured values. For example:

show call-control-profile full name profile_name

Extended DRX:
    Paging Time Window                                : 10 Seconds
    eDRX Cycle Length                                 : 512 Seconds
    Downlink Buffer Duration in DDN Ack               : Enabled
    DL Buffering Suggested Packet count in DDN Ack    : 10

The edrx hsfn-start CLI command in the MME Service Configuration mode allows the operator to configure the Hyper-SFN Synchronization start time.

configure
   context context_name
      mme-service service_name
         edrx hsfn-start utc_Time
         no edrx hsfn-start
         end

Notes:

• The no option disables the H-SFN synchronization time configuration.

• The edrx command specifies the Extended Discontinuous Reception H-SFN start time.

• The hsfn-start keyword specifies the UTC Time at which H-SFN=0 starts. The time must be entered in the UTC Time format as follows: YYYY:MM:DD:hh:mm:ss. For example: 2016:03:01:12:34:56.

Verifying H-SFN Synchronization

The following command displays the new fields that are added to verify H-SFN synchronization:

show mme-service full service_name

Extended DRX:
      H-SFN Start: 2016:03:01:12:34:56

This section describes how to configure the T3415 eDRX timer. This timer is used to configure the eDRX paging timeout. The t3415-timeout keyword is added as part of the emm command in the MME Service Configuration mode. The emm command is used to configure evolved mobility management timer parameters such as timeout durations for timers and retransmission counts and for Non-Access Stratum (NAS) message retransmission in MME service.

configure
   mme-service service_name
      emm { implicit-detach-timeout detach_dur | mobile-reachable-timeout mob_reach_dur | t3346-timeout t3346_dur | t3412-extended-timeout t3412_ext_dur | t3412-timeout t3412_dur | t3413-timeout t3413_dur | t3415-timeout t3415_dur | t3422-timeout t3422_dur | t3423-timeout t3423_dur | t3450-timeout t3450_dur | t3460-timeout t3460_dur | t3470-timeout t3470_dur }
      default emm { implicit-detach-timeout | mobile-reachable-timeout | t3346-timeout | t3412-extended-timeout | t3412-timeout | t3413-timeout | t3415-timeout | t3422-timeout | t3423-timeout | t3450-timeout | t3460-timeout | t3470-timeout }

Notes:

• The keyword t3415-timeout t3415_dur is used to configure the T3415 paging timeout value. The t3415_dur is an integer value in the range 1 up to 20 seconds. The default value is 6 seconds.

Verifying the T3415 eDRX Timer

Execute the show mme-service full service_name command to verify the configured value of the T3415 timer.

For example: The T3415 Timeout parameter displays the configured value of T3415 timer as 3 seconds.

show mme-service full service_name

T3415 Timeout  :  3s

This section describes how to configure the T3415 eDRX timer in the LTE Paging Profile Configuration mode. This timer is used to configure the eDRX paging timeout. The t3415-timeout keyword is added as part of the paging-stage command under the LTE Paging Profile Configuration mode. The paging-stage command enables the operator to configure different stages of paging in the order of desired execution with parameters that control the pace, volume, and behavior of a given paging stage.

configure
   lte-policy policy_name
      paging-profile profile_name
         [ no ] paging-stage level match-criteria { ue-contact-time seconds | all } action { last-n-enb-last-tai max-n-enb value | all-enb-last-tai | all-enb-all-tai } t3413-timeout seconds max-paging-attempts attempts [ t3415-timeout t3415_dur ]
         end

Notes:

• The t3415-timeout t3415_dur keyword is used to configure the T3415 paging timeout value. The t3415_dur is an integer ranging from 1 to 20 seconds.

• The no keyword disables the configuration.

• There are no re-tries in a paging stage.

• This command is disabled by default.

The following bulk statistics are added in the MME Schema in support of the eDRX feature.

• attached-edrx-subscriber - The current number of attached subscribers in eDRX mode.

• ddn-rejects-edrx - The total number of DDN rejects due to eDRX ever since the chassis was up.

See the Statistics and Counters Reference for more information.

Diameter Attribute Value Pairs (AVPs) carry specific authentication, accounting, authorization, routing and security information as well as configuration details for the request and reply. The following Diameter attributes are added in support of this feature:

DL-Buffering-Suggested-Packet-Count

This AVP indicates the DL buffering suggested packet count.

Vendor ID 10415

VSA Type 1674

AVP Type Integer32

AVP Flag V-bit is set to true, M-bit is set to false.