Initial and retransmissions of data for V2X transmissions

1. An integrated circuit configured to control operation of a transmitting device for transmitting data via a sidelink interface to one or more receiving devices, wherein the data transmission includes an initial data transmission and one or more data retransmissions, the integrated circuit comprising:

receiving circuitry, which, in operation, performs a resource sensing procedure to acquire information about radio resources usable by the transmitting device;

control circuitry, which, in operation,

responsive to data becoming available for transmission, performs an autonomous radio resource allocation to select time-frequency radio resources within a transmission window for the initial data transmission, based on the information acquired in the resource sensing procedure during a sensing window before the data becoming available for transmission, and

determines a data transmission timing pattern among a plurality of data transmission timing patterns, each data transmission timing pattern indicating a data transmission timing; and

transmitting circuitry, which, in operation,

performs the initial data transmission using the selected time-frequency radio resources,

determines, based on the data transmission timing indicated by the determined data transmission timing pattern and a time gap between the initial data transmission and the one or more data retransmissions, a data retransmission timing, and

performs the one or more data retransmissions at the retransmission timing,

wherein the time gap is configurable, independently of the determined data transmission timing pattern, and is made known to the one or more receiving devices, and

wherein the one or more data retransmissions are performed within a time span defined by a length of the determined data transmission timing pattern.

2. The integrated circuit according to claim 1 , wherein the plurality of data transmission timing patterns indicate different numbers of data transmissions, and the control circuitry, in operation,

determines the data transmission timing pattern among data transmission timing patterns corresponding to a total number of transmissions to be performed for the data, wherein the total number of transmissions is determined by the control circuitry or is preconfigured, and

determines the data transmission timing pattern either randomly or based on the information acquired in the resource sensing procedure during the sensing window.

3. The integrated circuit according to claim 1 , wherein the transmitting circuitry, in operation, transmits a scheduling assignment indicating the selected time-frequency radio resources for the initial data transmission and identifying the determined data transmission timing pattern.

4. The integrated circuit according to claim 1 , wherein the determined data transmission timing pattern indicates only one data transmission, wherein the control circuitry, in operation,

determines data retransmission candidates within the transmission window by repeating the determined data transmission timing pattern a plurality of times within the transmission window,

determines which of the data retransmission candidates are to be used for performing the one or more data retransmissions, depending on a total number of transmissions to be performed for the data, wherein the total number of transmissions is determined by the control circuitry or is preconfigured, and

determines the data transmission timing pattern and which of the data retransmission candidates are to be used based on the information acquired in the resource sensing procedure during the sensing window.

5. The integrated circuit according to claim 4 , wherein the transmitting circuitry, in operation, transmits a scheduling assignment indicating the selected time-frequency radio resources for the initial data transmission and identifying the determined data transmission timing pattern, and

wherein the scheduling assignment further includes a bitmap, wherein bits of the bitmap are respectively associated with one of the plurality of repeated data transmission timing patterns.

6. The integrated circuit according to claim 1 , wherein the one or more data retransmissions are performed using the same frequency radio resources as used for the initial data transmission or using frequency radio resources determined by the control circuitry from the frequency radio resources used for the initial data transmission based on a frequency hopping pattern, or

wherein the control circuitry, in operation, determines for the one or more data retransmissions whether to use the same frequency radio resources as for the initial data transmission or to use frequency radio resources following the frequency hopping pattern, based on the information acquired in the resource sensing procedure during the sensing window, and

wherein the transmitting circuitry, in operation, transmits a scheduling assignment indicating whether or not a frequency hopping pattern is used by the transmitting device for determining frequency radio resources used for the one or more data retransmissions.

7. The integrated circuit according to claim 1 , wherein the determined data transmission timing pattern indicates only one transmission, wherein the control circuitry, in operation,

determines a preferred transmission timing, after the initial data transmission timing, for one of the one or more data retransmissions based on the information acquired in the resource sensing procedure during the sensing window,

determines the data transmission timing pattern such that the one transmission indicated by the data transmission timing pattern coincides with the preferred transmission timing when the data transmission timing pattern is repeated a plurality of times within the transmission window with respect to the timing of the initial data transmission,

determines data retransmission candidates within the transmission window by repeating the data transmission timing pattern, and

determines which of the data retransmission candidates are to be used for performing remaining ones of the one or more data retransmissions, based on the information acquired in the resource sensing procedure during the sensing window and depending on a total number of transmissions to be performed for the data, wherein the total number of transmissions is determined by the control circuitry or is preconfigured, and

wherein the transmitting circuitry, in operation, performs the one of the one or more data retransmissions at the preferred transmission timing, and performs the remaining ones of the one or more data retransmissions at the retransmission candidates determined to be used.

8. The integrated circuit according to claim 6 , wherein the transmitting circuitry, in operation, transmits a scheduling assignment indicating frequency radio resources for the data retransmission at the preferred transmission timing, as an offset with respect to frequency radio resources for the initial data transmission, and

wherein the remaining data retransmissions are performed using the same frequency radio resources as used for the initial data transmission or the same frequency radio resources as used for the data retransmission at the preferred transmission timing, or

wherein the remaining data retransmissions are performed using frequency radio resources determined by the control circuitry based on a frequency hopping pattern from the frequency radio resources used for the initial data transmission or from the frequency radio resources used for the data retransmission at the preferred transmission timing, and

wherein the scheduling assignment further indicates whether or not a frequency hopping pattern is used by the transmitting device for determining frequency radio resources used for the one or more data retransmissions.

9. The integrated circuit according to claim 1 , wherein the data transmission timing pattern has a length of a plurality of bits, and each bit of the data transmission timing pattern indicates whether or not a transmission of the data is to be performed at a transmission timing associated with the respective bit position, and

wherein the data transmission timing pattern is positioned in the timing window with respect to the initial data transmission so as to also indicate or not indicate the initial data transmission.

10. The integrated circuit according to claim 1 , wherein a data resource pool includes a plurality of time-frequency radio resources available for the transmitting device, and the data resource pool is divided into time-frequency radio resources available for performing the initial data transmission and into time-frequency radio resources available for performing the one or more data retransmissions,

wherein the control circuitry, in operation, selects, during the autonomous radio resource allocation, the time-frequency radio resources for the initial data transmission among the time-frequency radio resources available for performing the initial data transmission.

11. The integrated circuit according to claim 1 , wherein the plurality of time-frequency radio resources in the data resource pool are divided in a time domain between the time-frequency radio resources available for performing the initial data transmission and the time-frequency radio resources available for performing the one or more data retransmissions, and

wherein the division of the data resource pool is preconfigured or configured by a radio base station controlling the transmitting device.

12. The integrated circuit according to claim 1 , wherein the resource sensing procedure includes:

monitoring scheduling assignments transmitted by other transmitting devices indicating radio resources reserved by the other transmitting devices, and

measuring a received signal energy in radio resources to identify radio resources that are used by other transmitting devices,

wherein the autonomous radio resource allocation includes excluding the radio resources reserved by the other transmitting devices from usable radio resources.