Wireless telecommunications apparatus and methods
A method including: establishing a first set of radio resources available for use by a terminal device for transmitting uplink data to a first network access node; establishing a shared set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node and a second network access node; determining uplink data has become available for transmission; selecting radio resources to use for transmitting the uplink data from within the shared set of radio resources if it is determined the terminal device is in a boundary region between a first communication cell and a second communication cell; and selecting radio resources to use for transmitting the uplink data from within the first set of radio resources if it is determined the terminal device is within the first communication cell and not in the boundary region.
1. A method of transmitting uplink data in a wireless telecommunications system comprising a terminal device, a first network access node supporting communications in a first communication cell and a second network access node supporting communications in a second communication cell; wherein the method comprises:
establishing a first set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node;
establishing a shared set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node and to the second network access node, wherein the first set of radio resources and the shared set of radio resources are different sets of radio resources;
determining uplink data has become available for transmission;
selecting radio resources to use for transmitting the uplink data from within the shared set of radio resources if it is determined the terminal device is in a boundary region between the first communication cell and the second communication cell; and
selecting radio resources to use for transmitting the uplink data from within the first set of radio resources if it is determined the terminal device is within the first communication cell and not in the boundary region between the first communication cell and the second communication cell.
2. The method of claim 1 , further comprising:
establishing a second set of radio resources available for use by the terminal device for transmitting uplink data to the second network access node, wherein the second set of radio resources and the shared set of radio resources are different sets of radio resources; and
selecting radio resources to use for transmitting the uplink data from within the second set of radio resources if it is determined the terminal device is within the second communication cell and not in the boundary region between the first communication cell and the second communication cell.
3. The method of claim 1 , wherein the shared set of radio resources is established by the terminal device from information transmitted by the first network access node.
4. The method of claim 1 , wherein the step of establishing the shared set of radio resources is performed in association with a handover procedure for handing over the terminal device from the first network access node to the second network access node.
5. The method of claim 4 , wherein the handover procedure is a make-before-break handover procedure in which the terminal device establishes a radio connection with the second network access node before the terminal device releases a radio connection with the first network access node.
6. The method of claim 1 , further comprising the terminal device transmitting uplink reference signalling to allow the second network access node to establish a transmission characteristic to be used for subsequent transmissions from the terminal device to the second network access node, and receiving an indication of the transmission characteristic from the second network access node before being handed over to the second network access node.
7. The method of claim 6 , wherein the transmission characteristic comprises at least one of an indication of a timing advance, an indication of a transmission power and/or an indication of a frequency correction.
8. The method of claim 1 , wherein the first network access node and the second network access node are time synchronised in respect of their respective radio frame structures for uplink data.
9. The method of claim 1 , further comprising transmitting the uplink data using the radio resources selected from within the shared set of radio resources using a transmission scheme that does not require time synchronisation between the terminal device and a receiving entity for the receiving entity to be able to receive the uplink data.
10. The method of claim 9 , wherein the transmission scheme comprises a code division multiple access, CDMA, scheme.
11. The method of claim 1 , wherein measurements of a characteristic of radio channel quality between the terminal device and at least one of the first network access node and the second network access node are used to determine whether the terminal device is in the boundary region.
12. The method of claim 11 , wherein the terminal device is considered to be in the boundary region if: (i) the measurements of the characteristic of radio channel quality indicate the radio channel quality between the terminal device and the first network access node is below a first predefined threshold level while the terminal device is in the first communication cell, and/or (ii) the measurements of the characteristic of radio channel quality indicate the radio channel quality between the terminal device and the second network access node is above a second predefined threshold level while the terminal device is in the first communication cell, and/or (iii) wherein the measurements of the characteristic of radio channel quality indicate the difference in radio channel quality between the terminal device and the first network access node and between the terminal device and the second network access node is below a third predefined threshold level.
13. A terminal device for use in a wireless telecommunications system comprising the terminal device, a first network access node supporting communications in a first communication cell and a second network access node supporting communications in a second communication cell; wherein the terminal device comprises controller circuitry and transceiver circuitry configured to operate together such that the terminal device is operable to:
establish a first set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node;
establish a shared set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node and to the second network access node, wherein the first set of radio resources and the shared set of radio resources are different sets of radio resources;
determine uplink data has become available for transmission;
select radio resources to use for transmitting the uplink data from within the shared set of radio resources if it is determined the terminal device is in a boundary region between the first communication cell and the second communication cell; and
select radio resources to use for transmitting the uplink data from within the first set of radio resources if it is determined the terminal device is within the first communication cell and not in the boundary region between the first communication cell and the second communication cell.
14. Circuitry for terminal device for use in a wireless telecommunications system comprising the terminal device, a first network access node supporting communications in a first communication cell and a second network access node supporting communications in a second communication cell; wherein the circuitry comprises controller circuitry and transceiver circuitry configured to operate together such that the circuitry is operable to:
establish a first set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node;
establish a shared set of radio resources available for use by the terminal device for transmitting uplink data to the first network access node and to the second network access node, wherein the first set of radio resources and the shared set of radio resources are different sets of radio resources;
determine uplink data has become available for transmission;
select radio resources to use for transmitting the uplink data from within the shared set of radio resources if it is determined the terminal device is in a boundary region between the first communication cell and the second communication cell; and
select radio resources to use for transmitting the uplink data from within the first set of radio resources if it is determined the terminal device is within the first communication cell and not in the boundary region between the first communication cell and the second communication cell.