Node and method for buffering downlink data
Example embodiments presented herein are directed towards a mobility management node and SGW or Gn/Gp-SGSN, and corresponding methods therein, for downlink data buffering in a wireless communications network. Such buffering is useful when the wireless device is in a power saving state e.g. PSM or eDRX. Thus, since the downlink data is buffered, there is no longer a need for multiple Downlink Data Notifications to be sent.
1. A method, in a Serving Gateway, SGW, or a Gn/Gp-Serving General Packet Radio Service Support Node, Gn/Gp-SGSN, for downlink data buffering in a wireless communications network, the method comprising:
sending, to a mobility management node, a Downlink Data Notification, DDN, for a downlink data packet for a wireless device in an idle mode;
receiving, from the mobility management node, a DDN Acknowledgement comprising one or more of a flag, a cause code and a buffer time value indicating the downlink data packet is to be buffered in memory;
buffering the downlink data packet within the SGW or Gn/Gp-SGSN until a connection with the wireless device has been established for the downlink data packet to be delivered to the wireless device or until a time indicated by the buffer time value has expired; and
sending, to an application server, an Internet Control Message Protocol, ICMP, control message, said message comprising a timestamp indicating a time remaining for which the downlink data will be buffered.
2. The method of claim 1 , wherein the DDN Acknowledgement is a DDN reject message, the method further comprising determining if the wireless device is also in a power saving state.
3. The method of claim 1 , further comprising determining the buffer time value, the buffer time value representing a time in which the downlink data packet is to be buffered in the SGW or Gn/Gp-SGSN.
4. The method of claim 3 , wherein the determining if the wireless device is in a power saving state and/or the determining the buffer time valve is based on one or more of:
a duration of time the wireless device is in a power saving state;
a time remaining in a power saving state;
a subscribed Access Point Name, APN;
subscription parameters;
a received power saving schedule;
user equipment capability parameters; and
a configuration within the SGW or SGSN node.
5. The method of claim 1 , wherein the downlink data packet is a first downlink data packet and wherein the wireless device is in a power saving state during the buffering of the first downlink data packet, the method further comprising:
receiving, from a Packet Data Network Gateway, PGW, a further downlink data packet for the wireless device, wherein the wireless device is in the power saving state; and
buffering the further downlink data packet.
6. The method of claim 1 , further comprising receiving, from the mobility management node, a deferred paging capability or sleeping capability.
7. A Serving Gateway, SGW, or a Gn/Gp-Serving General Packet Radio Service Support Node, Gn/Gp-SGSN, for downlink data buffering in a wireless communications network, the SGW or Gn/Gp-SGSN comprising:
a transmitter;
a receiver; and
processing circuitry coupled to the transmitter and the receiver, wherein the processing circuitry is configured to:
employ the transmitter to transmit, to a mobility management node, a Downlink Data Notification, DDN, for a downlink data packet for a wireless device in an idle mode,
receive via the receiver, from the mobility management node, a DDN Acknowledgement comprising one or more of a flag, a cause code and a buffer time value indicating the downlink data packet is to be buffered in memory,
buffer the downlink data packet within the SGW or Gn/Gp-SGSN until the connection with the wireless device has been established for the downlink data packet to be delivered to the wireless device or until a time indicated by the buffer time value has expired, and
employ the transmitter to transmit, to an application server, an Internet Control Message Protocol, ICMP, control message, said message comprising a timestamp indicating a time remaining for which the downlink data will be buffered.
8. The SGW or Gn/Gp-SGSN of claim 7 , wherein the DDN Acknowledgement is a DDN reject message, the processing circuitry is further configured to determine if the wireless device is also in a power saving state.
9. The SGW or Gn/Gp-SGSN of claim 7 , wherein the processing circuitry is further configured to determine a buffer time value, the buffer time value representing a time in which the downlink data packet is to be buffered in the SGW or Gn/Gp-SGSN.
10. The SGW or Gn/Gp-SGSN of claim 9 , wherein the processing circuitry is further configured to determine if the wireless device is in the sleep mode and/or to determine the buffer time value based onone or more of:
a duration of time the wireless device is in a power saving state;
a time remaining in a power saving state;
a subscribed Access Point Name, APN;
subscription parameters;
a received power saving schedule;
user equipment capability parameters; and
a configuration within the SGW or Gn/Gp-SGSN node.
11. The SGW or Gn/Gp-SGSN of claim 7 , wherein the downlink data packet is a first downlink data packet and wherein the wireless device is in a power saving state during the buffering of the first downlink data packet:
the processing circuitry is further configured to:
receive via the receiver, from a Packet Data Network Gateway, PGW, a further downlink data packet for the wireless device, wherein the wireless device is in the power saving state, and
buffer the further downlink data packet.
12. The SGW or Gn/Gp-SGSN of claim 7 , wherein the processing circuitry is further configured to:
receive via the receiver, from the mobility management node, a deferred paging capability or sleeping capability.