Short message transmission and handover procedures
A method performed by a connectivity-related network entity is provided. The method includes: receiving, from a Packet Data Network (PDN) gateway and a Serving Gateway (SGW), a Short Message Service (SMS) message to be sent in a downlink; determining to use a control plane only, out of the control plane and a user plane, for transferring the SMS message; transmitting a trigger message to a user equipment to initiate establishment of connectivity with the user equipment via the control plane only and not via the user plane, wherein the user equipment starts a timer when the establishment of the control plane connectivity is initiated; receiving a response message from the user equipment; encapsulating the SMS message in a security protected Non-Access Stratum (NAS) message; and transmitting the security protected NAS message to the user equipment, in receipt of which the user equipment stops the timer.
1. An integrated circuit which, in operation, controls a user equipment, the integrated circuit comprising:
receiving circuitry, which, in operation, receives a trigger message from a connectivity-related network entity to establish connectivity with a mobile communication network via a control plane only and not via a user plane, and
control circuitry, which is coupled to the receiving circuitry and which, in response to the triggering message, establishes control plane connectivity with the connectivity-related network entity,
wherein, the control circuitry starts a timer when initiating the establishment of the control plane connectivity and stops the timer when at least one of a plurality of defined conditions is met.
2. The integrated circuit according to claim 1 , wherein the plurality of defined conditions include at least one of:
a) receipt of a security protected Non-Access Stratum (NAS) message;
b) establishment of a bearer for the user plane; and
c) release of a Radio Resource Control (RRC) connection.
3. The integrated circuit according to claim 1 , comprising:
transmitting circuitry, which is coupled to the control circuitry and which, in operation, sends a Non-Access Stratum (NAS) service request to the connectivity-related network entity to establish the connectivity with the mobile communication network.
4. The integrated circuit according to claim 1 , wherein the connectivity-related network entity is a Mobility Management Entity (MME).
5. The integrated circuit according to claim 1 , wherein the timer is a control plane establishment timer or a radio resource release timer.
6. The integrated circuit according to claim 1 , wherein the timer is T 3417 timer defined in 3rd Generation Partnership Project (3GPP) standards.
7. The integrated circuit according to claim 1 , wherein the receiving circuitry, in operation, receives downlink small data from a base station in the mobile communication network, using a Radio Resource Control (RRC) message.