Protocol for map data transmission for infrastructure to vehicle communications
A method is provided for selectively transmitting stop sign intersection data to a vehicle in an infrastructure-to-vehicle communication system. The infrastructure-to-vehicle system includes a fixed entity for broadcasting wireless messages to vehicles in a predetermined area. The local intersection data is broadcast from a local intersection device at a first repetition rate. The local intersection data relates to the intersection in which the vehicle is currently approaching. Remote intersection data, such as map GID, is broadcast from the local intersection device at a second repetition rate. The remote intersection data relates to intersections beyond the vehicle's current approaching intersection. The second repetition rate is lower than the first repetition rate.
1. A method for selectively transmitting stop sign intersection data to a vehicle in an infrastructure-to-vehicle communication system, the infrastructure-to-vehicle communication system including a fixed entity for broadcasting wireless messages to vehicles in a predetermined area, the method comprising the steps of:
broadcasting local intersection data from a remote entity at a first repetition rate, the local intersection data relating to at least one intersection in the predetermined area; and
broadcasting remote intersection data from the remote entity at a second repetition rate, the remote intersection data relating to intersections beyond the predetermined area, the second repetition rate being lower than the first repetition rate.
2. The method of claim 1 wherein the first repetition rate is determined as a function of successfully broadcasting local intersection data to vehicles while the vehicles are within a first broadcast region and traveling within a set speed limit, the first broadcast region being a respective region between a maximum broadcasting range of the first entity and a critical distance from a designated stopping location of the intersection.
3. The method of claim 2 wherein the first repetition rate for transmitting the local intersection data is determined by formula:
f
L
=
(
N
(
V
)
R
-
d
)
where f L is the first repetition rate, N is a number of consecutive packet transmissions needed by a road side equipment to obtain a respective packet reception probability, V is the speed limit, R is the broadcasting range, and d is the critical distance between a vehicle and the stopping location at the intersection.
4. The method of claim 3 wherein the second repetition rate is determined as a function of broadcasting remote intersection data within a second broadcast region that successfully provides the remote intersection data to vehicles while traveling within the second broadcast region, the second broadcast region relating to an entire broadcast region within the maximum broadcasting range of the fixed entity.
5. The method of claim 4 wherein the second repetition rate for transmitting the remote intersection data is determined by formula:
f
r
=
N
(
V
)
2
(
R
)
where f r is the second repetition rate, N is the number of consecutive packet transmissions needed by the road side equipment to obtain a respective packet reception probability, V is the speed limit, and R is the broadcasting range.
6. The method of claim 5 wherein the packet reception probability is determined by formula:
P= 1−PER N
where P is a resulting probability of receiving the data packet based on the number of consecutive packet transmissions, PER is the packet error rate, and N is the number of consecutive packet transmissions needed by the road side equipment to obtain a respective packet reception probability.
7. The method of claim 1 wherein the local and remote intersection data broadcast by the remote entity includes geometric intersection data maplets.
8. The method of claim 1 further comprising the steps of:
receiving the local intersection data;
applying a stop sign assistance routine for analyzing a vehicle speed in relation to a designated stopping location at the intersection as the vehicle approaches the intersection; and
actuating an alert in response to the stop sign assistance routine determining that the vehicle speed exceeds a threshold for stopping the vehicle the designated stopping location.
9. An infrastructure-to-vehicle system for broadcasting wireless messages to vehicles traveling in a predetermined area, the infrastructure-to-vehicle system including a fixed road side entity for broadcasting wireless messages to vehicles in the predetermined area, the fixed road side entity broadcasting system comprising:
a processor for selectively controlling a broadcast of wireless messages in the predetermined area, the processor segregating local intersection data and remote intersection data, the local intersection data relating to a local intersection in the predetermined area, the remote intersection data relating to intersections beyond the predetermined area; and
a transmitter for broadcasting the local intersection data at a first repetition rate and the remote intersection data at a second repetition rate, wherein the second repetition rate is lower than the first repetition rate.
10. The system of claim 9 wherein the fixed road side entity is disposed at the local intersection.
11. The system of claim 9 wherein the processor selectively controls the transmitter for broadcasting the wireless messages, wherein local intersection data broadcast at the first repetition rate is determined as a function of successfully broadcasting local intersection data to the vehicles while the vehicles are within a first broadcast region and traveling within a set speed limit, and wherein the first broadcast region is located between a maximum broadcasting range of the transmitter and a location of a critical distance from a designated stopping location of the intersection.
12. The system of claim 11 wherein the first repetition rate for transmitting the local intersection data is determined by formula:
f
L
=
N
(
V
)
(
R
-
d
)
where f L is the first repetition rate, N is a number of consecutive packet transmissions needed by the fixed road-side entity to obtain a respective packet reception probability, V is the speed limit, R is the broadcasting range, and d is the critical distance between the vehicle and the stopping location at the intersection.
13. The system of claim 12 wherein the second repetition rate is determined as a function of broadcasting remote intersection data within a second broadcast region that successfully provides the remote intersection data to vehicles while traveling within the second broadcast region.
14. The system of claim 13 wherein the second repetition rate for transmitting the remote intersection data is determined by formula:
f
r
=
N
(
V
)
2
(
R
)
where f r is the second repetition rate, N is the number of consecutive packet transmissions needed by the fixed road-side entity to obtain a respective packet reception probability, V is the speed limit, and R is the broadcasting range.
15. The system of claim 14 wherein the fixed road-side entity determines a probability of reception, the probability of reception relates to a probability of successfully receiving the wireless message within the respective regions, the probability is determined by formula:
P= 1−PER N
where P is a resulting probability of receiving the wireless message based on the number of consecutive packet transmissions, PER is a packet error rate, and N is a number of consecutive packet transmissions needed by the fixed road-side entity to obtain a respective packet reception probability.
16. The system of claim 14 wherein the local and remote intersection data broadcast by a remote entity includes geometric intersection data maplets.
17. The system of claim 9 further comprising a receiver within a vehicle for receiving the local intersection data, the receiver providing the intersection data to a vehicle processing unit for applying a stop sign assistance routine for analyzing a vehicle speed in relation to a designated stopping location at the intersection as the vehicle approaches the intersection wherein an alert signal is actuated in response to the stop sign assistance routine determining that the vehicle speed exceeds a threshold for stopping the vehicle a designated stopping location.
18. The system of claim 17 further comprising a memory device for storing the remote intersection data, wherein the remote intersection data is retrieved by the processor as the vehicle approaches a respective intersection having an associated maplet stored in the memory device.
19. The system of claim 17 wherein the receiver is integrated as part of a wireless radio for communicating with the fixed road-side entity.