Wireless timing adjustment for periodical traffic of multiple time domains
A communication terminal is provided for supporting a periodical data flow by forwarding messages received from a communication network to an external node not synchronised with the communication network. The communication terminal is configured to obtain one or more timing adjustment indications from an access node of the communication network and adjust the transmission and/or reception timing of the periodical data flow in dependence on the timing adjustment indication(s). The one or more timing adjustment indications are based on clock mismatch information between the communication terminal and the external node and a holding time.
1. A communication terminal for supporting a periodical data flow by forwarding messages received from a communication network to an external node not synchronized with the communication network, the communication terminal comprising:
processing circuitry configured to:
obtain one or more timing adjustment indications provided by an access node of the communication network, the one or more timing adjustment indications being based on (i) clock mismatch information between the communication terminal and the external node and (ii) a holding time; and
adjust transmission and/or reception timing of the periodical data flow in dependence on the one or more timing adjustment indications.
2. The communication terminal as claimed in claim 1 , wherein the processing circuitry is further configured to:
estimate the clock mismatch information between the communication terminal and the external node; and
provide the estimated clock mismatch information and the holding time to the access node of the communication network.
3. The communication terminal as claimed in claim 2 , wherein the estimated clock mismatch information is based on one of:
(i) a periodicity with which messages of the periodical data flow are transmitted and/or received by the communication network according to a frequency of an internal clock of the communication network; and
(ii) a ratio of a frequency of a clock of the external node and the frequency of the internal clock of the communication network.
4. The communication terminal as claimed in claim 1 , wherein the processing circuitry is further configured to obtain estimated clock mismatch information from the access node and adjust egress transmission timing of the periodic data flow so as to mitigate a mismatch between a clock of the communication network and a clock of the external node.
5. The communication terminal as claimed in claim 1 , wherein the processing circuitry is further configured to quantize the holding time and report the holding time to the access node.
6. The communication terminal as claimed in claim 1 , wherein the communication terminal is a user equipment device and wherein the access node is a node B.
7. The communication terminal as claimed in claim 4 , wherein the estimated clock mismatch information is based on one of:
(i) a periodicity with which messages of the periodical data flow are transmitted and/or received by the communication network according to a frequency of an internal clock of the communication network; and
(ii) a ratio of a frequency of a clock of the external node and the frequency of the internal clock of the communication network.