Methods for data communication to a platoon of connected vehicles
It is possible to reduce latency and/or overhead when performing a platoon handover by using the leading vehicle in the platoon to communicate handover requests and/or initial resource requests (e.g., random access transmissions) on behalf of trailing vehicles in the platoon. In one example, a leading vehicle in a platoon communicates a handover request to a source AP to request handover of the entire platoon from the source AP to a target AP. In such an example, the source AP then communicates handover commands to each vehicle in the platoon without receiving separate handover requests from the trailing vehicles, thereby reducing overhead in the access network. The handover commands notify the trailing vehicles of the handover, and may be sequentially communicated to the trailing vehicles based on their order in the platoon.
1. A method for low overhead control signaling, the method comprising:
receiving, by an access point, channel information and platoon information from a leading vehicle in a platoon of vehicles, wherein the platoon information includes at least one of a speed of the platoon of vehicles and a spacing between vehicles in the platoon of vehicles;
assigning, by the access point, a beam direction parameter to the leading vehicle at a first time instance based on the channel information received from the leading vehicle, the beam direction parameter including a set of beamforming weights or a spatial direction to be used for an uplink or downlink transmission; and
assigning, by the access point, the beam direction parameter to a trailing vehicle at a second time instance based on at least one of the speed in which the platoon of vehicles is traveling and the spacing between the vehicles in the platoon of vehicles.
2. The method of claim 1 , wherein the access point further assigns the same uplink or downlink modulation and coding scheme (MCS) level to the leading vehicle and the trailing vehicle based on the platoon information.
3. The method of claim 1 , wherein the access point further assigns the same uplink timing advance to the leading vehicle and the trailing vehicle based on the platoon information, the uplink timing advance corresponding to a propagation delay of an uplink signal communicated to the access point.
4. A method for low overhead control signaling, the method comprising:
receiving, by a trailing vehicle in a platoon of vehicles, a beam direction parameter assigned to the trailing vehicle from an access point prior to communicating any channel information to the access point, the beam direction parameter assigned to the trailing vehicle having been assigned based on a beam direction parameter associated with a leading vehicle in the platoon of vehicles during a first time instance and at least one of a speed in which the platoon of vehicles is traveling and a spacing between the vehicles in the platoon of vehicles, the beam direction parameter assigned to the trailing vehicle including a set of beamforming weights or a spatial direction to be used for an uplink or downlink transmission; and
transmitting a signal to the access point according to the beam direction parameter assigned to the trailing vehicle during a second time instance.
5. The method of claim 4 , wherein the access point further assigns the same downlink modulation and coding scheme (MCS) level assigned by the access point to the leading vehicle and the trailing vehicle based on at least one of the speed of the platoon of vehicles and the spacing between vehicles in the platoon of vehicles.
6. The method of claim 5 , further comprising:
estimating a channel information value based on a downlink reference signal received from the access point;
comparing a channel information value associated with the assigned MCS parameter with the estimated channel information value; and
transmitting an uplink feedback message to the access point upon determining that a difference between the channel information value associated with the assigned MCS parameter and the estimated channel information value exceeds a threshold, the uplink feedback message including the estimated channel information value.
7. The method of claim 4 , wherein the access point further assigns the same uplink timing advance to the leading vehicle and the trailing vehicle based on at least one of the speed of the platoon of vehicles and the spacing between vehicles in the platoon of vehicles, the uplink timing advance corresponding to a propagation delay of an uplink signal communicated to the access point.
8. The method of claim 4 , wherein the trailing vehicle further received a sequence of timing advances from the access point, and wherein transmitting the signal comprises:
transmitting a first uplink signal to the access point according to a first timing advance in the sequence of timing advances; and
after expiration of a delay period, transmitting a second uplink signal to the access point according to a second timing advance in the sequence of timing advances.
9. A method for low overhead control signaling, the method comprising:
receiving, by an access point, channel information and platoon information from a leading vehicle in a platoon of vehicles, wherein the platoon information includes at least one of a speed of the platoon of vehicles and a spacing between vehicles in the platoon of vehicles;
assigning, by the access point, a first beam direction parameter to the leading vehicle in the platoon of vehicles at a first time instance; and
assigning, by the access point, a second beam direction parameter to a trailing vehicle in the platoon of vehicles at a second time instance based on the first beam direction parameter and at least one of the spacing between the leading vehicle and the trailing vehicle and the speed of the platoon of vehicles, the first beam direction parameter and the second beam direction parameter including respective sets of beamforming weights or respective spatial directions to be used for uplink or downlink transmissions.
10. The method of claim 9 , wherein the access point further assigns a transmit power level to the trailing vehicle based on the platoon information.
11. The method of claim 9 , wherein the access point further assigns an uplink timing advance to the trailing vehicle based on the platoon information.
12. An access point comprising:
a processor; and
a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
receive channel information and platoon information from a leading vehicle in a platoon of vehicles, wherein the platoon information includes at least one of a speed of the platoon of vehicles and a spacing between vehicles in the platoon of vehicles; and
assign a beam direction parameter to a trailing vehicle for use during a second time instance based on a beam direction parameter associated with the leading vehicle during a first time instance and at least one of the spacing between vehicles in the platoon of vehicles and the speed of the platoon of vehicles, the beam direction parameter assigned to the trailing vehicle including a set of beamforming weights or a spatial direction to be used for an uplink or downlink transmission.
13. The access point of claim 12 , wherein the access point further assigns a transmit power level to the trailing vehicle based on the platoon information.
14. The access point of claim 12 , wherein the access point further assigns an uplink timing advance to the trailing vehicle based on the platoon information.
15. A trailing vehicle in a platoon of vehicles, the trailing vehicle comprising:
a processor; and
a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
receive a beam direction parameter assigned to the trailing vehicle from an access point prior to communicating any channel information to the access point, the beam direction parameter assigned to the trailing vehicle having been assigned based on a beam direction parameter associated with a leading vehicle in the platoon of vehicles during a first time instance and at least one of a speed in which the platoon of vehicles is traveling and a spacing between vehicles in the platoon of vehicles, the beam direction parameter assigned to the trailing vehicle including a set of beamforming weights or a spatial direction to be used for the uplink or downlink transmission; and
transmit a signal to the access point according to the beam direction parameter assigned to the trailing vehicle during a second time instance.
16. The trailing vehicle of claim 15 , wherein the access point further assigns the same downlink modulation and coding scheme (MCS) level assigned by the access point to the leading vehicle and the trailing vehicle based on at least one of the speed of the platoon of vehicles and the spacing between vehicles in the platoon of vehicles.
17. The trailing vehicle of claim 16 , wherein the programming further includes instructions to:
estimate a channel information value based on a downlink reference signal received from the access point;
compare a channel information value associated with the assigned MCS parameter with the estimated channel information value; and
transmit an uplink feedback message to the access point upon determining that a difference between the channel information value associated with the assigned MCS parameter and the estimated channel information value exceeds a threshold, the uplink feedback message including the estimated channel information value.
18. The trailing vehicle of claim 15 , wherein the access point further assigns the same uplink timing advance to the leading vehicle and the trailing vehicle based on at least one of the speed of the platoon of vehicles and the spacing between vehicles in the platoon of vehicles, the uplink timing advance corresponding to a propagation delay between the leading vehicle and the access point.
19. The trailing vehicle of claim 15 , wherein the trailing vehicle further received a sequence of timing advances from the access point during the receiving step, and wherein programming further includes instructions to:
transmit a first uplink signal to the access point according to a first timing advance in the sequence of timing advances; and
after expiration of a delay period, transmit a second uplink signal to the access point according to a second timing advance in the sequence of timing advances.
20. An access point comprising: a processor; and
a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
receive channel information and platoon information from a leading vehicle in a platoon of vehicles, wherein the platoon information includes at least one of a speed of the platoon of vehicles and a spacing between vehicles in the platoon of vehicles;
assign a first beam direction parameter to the leading vehicle in the platoon of vehicles at a first time instance; and
assign a second beam direction parameter to a trailing vehicle in the platoon of vehicles at a second time instance based on the first beam direction parameter and at least one of the spacing between vehicles in the platoon of vehicles and the speed of the platoon of vehicles, the first beam direction parameter and the second beam direction parameter including respective sets of beamforming weights or respective spatial directions to be used for uplink or downlink transmissions.
21. The access point of claim 20 , wherein the access point further assigns a transmit power level to the trailing vehicle based on the platoon information.
22. The access point of claim 20 , wherein the access point further assigns an uplink timing advance to the trailing vehicle based on the platoon information.