Sequence number update
The invention relates to a method and device in a communications network when a User Equipment, UE, needs to update a next expected Transmission Sequence Number, TSN, continuously in order to avoid discarding successive transmissions. The method comprises: resetting a next expected TSN value in said network and UE to predetermined values after a predetermined inactivity time.
1. A method for managing communication at a mobile terminal, the method being implemented by the mobile terminal and comprising:
initializing a next expected sequence number associated with common packet data units having a shared destination address and shared sequence numbers;
after initializing the next expected sequence number, receiving an initial packet data unit having the shared destination address and comprising an initial shared sequence number;
starting a first timer associated with the common packet data units having the shared destination address and shared sequence numbers;
while the first timer is running:
accepting and storing all subsequent packet data units having the shared destination address;
resetting the first timer responsive to determining that one of said subsequent packet data units is correctly received;
starting a second timer responsive to determining that one of said subsequent packet data units has a sequence number higher than the next expected sequence number; and
responsive to expiration of the first timer, resetting the value of the next expected sequence number to a first predefined initial value, and resetting the upper boundary of a receiver window in the mobile terminal to a second predefined initial value.
2. The method of claim 1 further comprising proceeding to receive a subsequent next packet data unit when determining that the first timer has expired.
3. The method of claim 1 wherein the initial packet data unit is received on a control channel with the mobile terminal in a state of connecting to a data downlink channel.
4. The method of claim 3 wherein the state comprises an Enhanced CELL_FACH state.
5. The method of claim 1 wherein the mobile terminal is operating in an FDD (Frequency Division Duplex) or TDD (Time Division Duplex) wireless communication network.
6. The method of claim 1 wherein the shared destination address is a common H-RNTI (HS-DSCH Radio Network Temporary Identifier).
7. A mobile terminal for communication in a wireless communication network, comprising:
a communication unit configured to receive packet data units;
a measurement unit comprising a first timer associated with common packet data units having a shared destination address and shared sequence numbers;
a processing unit configured to:
initialize a next expected sequence number associated with common packet data units having a shared destination address and shared sequence numbers;
after initializing the next expected sequence number, receive an initial packet data unit having the shared destination address and comprising an initial shared sequence number;
start a first timer associated with the common packet data units having the shared destination address and shared sequence numbers;
while the first timer is running:
accept and store all subsequent packet data units having the shared destination address;
reset the first timer responsive to determining that one of said subsequent packet data units is correctly received;
start a second timer responsive to determining that one of said subsequent packet data units has a sequence number higher than the next expected sequence number; and
responsive to expiration of the first timer:
reset the next expected sequence number for the next expected packet data unit to a first predefined initial value; and
reset the upper boundary of its receiving window to a second predefined initial value.
8. A non-transitory computer-readable medium storing a computer program for managing communication in a mobile terminal, the computer program comprising program instructions that configure the mobile terminal to:
initialize a next expected sequence number associated with common packet data units having a shared destination address and shared sequence numbers;
after initializing the next expected sequence number, receive an initial packet data unit having the shared destination address and comprising an initial shared sequence number;
start a first timer associated with the common packet data units having the shared destination address and shared sequence numbers;
while the first timer is running:
accept and store all subsequent packet data units having the shared destination address;
reset the first timer responsive to determining that one of said subsequent packet data units is correctly received;
start a second timer responsive to determining that one of said subsequent packet data units has a sequence number higher than the next expected sequence number; and
responsive to expiration of the first timer, reset the value of the next expected sequence number to a first predefined initial value, and reset the upper boundary of a receiver window in the mobile terminal to a second predefined initial value.